An optimization technique applicable to the Yagi-Uda antenna was proposed in this paper. An objective function, which is the gain of the antenna in our case, was computed using method of moments. Design variables for the Yagi-Uda antenna were chosen with lengths, positions and diameters of the antenna elements. For the optimization process, the evolution strategy technique was adopted. The results were compared with existing results and showed better performances.

An amplitude modulation technique for increasing the laser penetration efficiency for metals has been studied. By chopping electro-optically Nd:YAG laser pulse, the threshold energy for reliable hole drilling was decreased significantly and the penetration depth was increased. It was observed that the effect of chopping was optimal at 8-12 kHz with 60% duty cycle. It is believed that this improvement is due to an increase in the vapor recoil pressure and reduced plasma screening.

The shape of lossy material inside a waveguide matched load is optimally designed to give low reflection over a given frequency range. The 3 dimensional vector finite element mettled is used as an analysis tool which does not generate spurious mode. The optimizing process used in this parer is the Powell technique. The designed load gives the low reflection about -30 dB around 10GHz with 1.5 wavelength of the load length.

A reflection type SEED from LP-MOCVD grown InGaAs/GaAs ESQW structures, with 5% In fraction, has been fabricated and its basic characteristics were investigated. Its intrinsic region consists of 50 pairs of alternating $100{\AA}$ $In_{0.05}Ga_{0.95}As$ barrier and $100{\AA}$ GaAs layers. And a multilayer reflector stack of $Al_{0.12}Ga_{0.88}As(641{\AA})-/AlAs(774{\AA})$ was vertically integrated below the p-i-n structures. The device processing includes the mesa etching, insulator deposition, indium metallization, and thermal alloy for Ohmic contact. Photocurrent spectrum measurement showed the exciton absorption peak at 905nm and availability as a optical switching device. This device showed a contrast ratio of 2:1 by the reflectance spectrum measurement.

The properties of $TiN/TiSi_2$ bilayer formed by a rapid thermal anneal ing is investigated when thin $SiO_2$ film exists at the Ti-Si interface. The competitive reaction for the $TiN/TiSi_2$ bilayer occurs above $600^{\circ}C$. The thickness of the $TiSi_2$ layer decreases with increasing $SiO_2$ film thickness while the TiN layer increases at the competitive reaction. The composition of TiN layer is changed to the $TiN_xO_y$ film due to the thin $SiO_2$ layer at the Ti-Si interface while the structure of the TiN and $TiSi_2$ layers was not changed.

Applications of poly-Si layers which are important as sensing and structural material of various sensors were reviewed in this research. A piezoresistive pressure sensor with piezoresistors has sensitivity of $6.93{\mu}$ V/(VmmHg) within 300mmHg. Temperature sensor was studied with measurement range of $-40{\sim}140^{\circ}C$ and $400{\sim}800^{\circ}C$ using boron-doped and undoped poly-Si resistors, respectively. Poly-Si layer was used to transduce volume change of polyimide to stress of silicon diaphragm for humidity sensor.

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. This paper describes the effects of lithium salts, plasticizer addition and temperature dependence of conductivity of PEO electrolytes. Polyethylene oxide(PEO) based polymer electrolyte films were prepared by solution casting an acetonitrile solution of preweighed PEO and Li salt. After solvent evaporation, the electrolyte films were vacuum-dried at $60^{\circ}C$ for 48h, the thickness of the films were $90{\sim}110{\mu}m$. The conductivity properties of prepared PEO electrolytes are summarized as follows. PEO electrolyte complexed with $LiClO_4$ shows the better conductivity of the others. $PEO-LiClO_4$ electrolyte when $EO/Li^+$ ratio is 8, showed the best conductivity. Optimum operating temperature of PEO electrolyte is $60^{\circ}C$. By adding propylene carbonate and ethylene carbonate to $PEO-LiClO_4$ electrolyte, its conductivity was higher than $PEO-LiClO_4$ without those. Also $PEO_8LiClO_4$ electrolyte remains static up to 4.5V vs. $Li/Li^+$.

In this work, polyimide thin films fabricated by the electrophoretic deposition are investigated as a humidity sensing material. Capacitance and impedance are measured with increasing relative humidity to find the nature of the film. From the results, the polyimide humidity sensor is not classified impedance change type but capacitance change type and appear more sensitive in the region of higher humidity than that of lower humidity.

TiAlN thin films were prepared by a multi target r.f magnetron sputtering system under different conditions. We have investigated the resistivity and T.C.R. (Temperature Coefficient of Resistance) characteristics of TiAlN films deposited on $Al_2O_3$ and glass substrates by sputtering in an $Ar:N_2$ gas mixture. We used Al and Ti metal as Target Material and $Ar:N_2$ gas as working gas. We varied the partial pressure ratio of $N_2/Ar$ from 0.2/7 to 1.0/6.2 (SCCM). And the R.F power of Ti and Al Target also were varied as 160/240, 200/200 and 240/160(W). In this experiment, we can get the precision thin film resistor with a very low T.C.R. (Temperature Coefficient of Resistance) below 25 ppm ${\Omega}/^{\circ}C$.

We have characterized XeCl excimer-laser-induced crystallization of thin amorphous silicon films deposited by PECVD (${\alpha}-Si:H$) and LPCVD(${\alpha}-Si$). The electrical and optical properties and surface roughness of crystallized thin films have been measured. The dc conductivities, crystallinity and surface roughness of the films increased as the laser energy density and shot density were increased. Also, we have investigated the effects of 2-step annealing employing SPC and ELA. The properties of 2-step annealed films were better than those of films annealed by ELA only.

SiN films were deposited in $Si_2H_6$(99.9%), $NH_3$(99.99%) gas mixture with carrier gas $N_2$ on Si substrate by ArF Excimer Laser CVD. SiN film deposition conditions that are substrate temperature and Laser average power were varied in order to investigate the dependence of SiN film on the condition. A post-deposition anneal was performed to examine variation of fixed charge density in the films. The deposition rate was increased as the substrate temperature and Laser power were increased during film deposition. The refractive index was increased with increasing substrate temperature, but it didn't have the dependence on Laser power. The fixed charge density was decreased when a post-deposition anneal was performed.

Thin amorphous film of $a-Se_{75}Ge_{25}$ acts as a positive resist in ion beam lithography. Previously, we reported the optical characteristics of amorphous $Se_{75}Ge_{25}$ thin film by the low-energy ion beam exposure and presented analytically calculated values such as ion range, ion concentration and ion transmission coefficient, etc. As the calculated results of analytical calculation, the energy loss per unit distance by $Ga^+$ ion is about $10^3[keV/{\mu}m]$ and nearly constant for all energy range. Especially, the projected range and struggling for 80 [KeV] $Ga^+$ ion energy are 0.0425[${\mu}m$] and 0.020[${\mu}m$], respectively. Hear, we present the results of Monte-Carlo computer simulation of Ga ion scattering, exposure and development in $a-Se_{75}Ge_{25}$ resist film for focused ion beam(FIB) lithography. Monte-Carlo method is based on the simulation of individual particles through their successive collisions with resist atoms. By the summation of the scattering events occurring in a large number N(N>10000) of simulated trajectories within the resist, the distribution for the range parameters is obtained. Also, the deposited energy density and the development pattern by a Gaussian or a rectangular ion beam exposure can be obtained.

(100), (110) and (111) Si wafers are etched by isotropic etching method, anisotropic etching method using KOH etchant and EPW etchant and combined two-step etching method to compare the results. Isotopic etching method is effective in fabrication of wedge-shaped tips, especially (110) Si. Anisotropic etching method of (100) Si using EPW etchant can fabricate sharp cone-shaped tips and isotropic etching after anisotropic etching of (100) Si can fabricate wedge-shaped tips.

0.15$(Ba_{0.95}Sr_{0.05})$O-0.15$(Sm_{2(1-x)}Nd-{2x})O_3-0.7TiO_2 (x=0{\sim}10[m/o])$ ceramics were fabricated by mixed-oxide method. Microwave dielectric properties was investigated with the contents of $Nd_2O_3$. Increasing the contents of $Nd_2O_3$ from 0 to 6[m/o], sintered density was increased 5.53 to $5.68[g/ cm^3]$. In the specimen with contents of $Nd_2O_3$(6[m/o]), dielectric content was maximum value of 78.14 and decreased with increasing the contents of $Nd_2O_3$. Quality factor was increased with the contents of $Nd_2O_3$.

Phsysical and dielectric properties of $(1-x)CaTiO_3-xLa(Zn_{1/2}Ti_{1/2})O_3$ ceramics were investigated at the temperature range of $25^{\circ}C$ to $80^{\circ}C$ at the frequency of 6 GHz. As increasing addition of the amount of $La(Zn_{1/2}Ti_{1/2})O_3$ to x = 5 mol,Q value was increased due to grain growth and increase of density. For more addition, Q value decreased due to electrical defect. Temperature coefficient of resonant frequency could be controlled by the amount of $La(Zn_{1/2}Ti_{1/2})O_3$, which could be explained by volume mixing rule.

Effects of molecular characteristics such as melt index and shapes of molecular weight distribution on the charge formation in LDPE have been investigated. Both homocharge and heterocharge were observed in LDPE depending on the value of melt index. It was found that the LDPE having intermediate melt indices shows heterocharge while the LDPE having small and high melt indecies shows homocharge. The shapes of molecular weight distributions were also found to affect the space charge in LDPE. These were explained by the role of short chains having low molecular weight in LDPE.

EPDM has excellent electric characteristics and so that it has been rapidly finding use is high voltage applications in recent years. At present EPDM is widely used for insulator of cable and accessories, and further the commercial use of Premolded housing for elbow surge arrester is started. In this paper, we have measured the temperature, pressure and voltages dependence of $tan{\delta}$ in EPDM. As a results, dielectric characteristics($tan{\delta}$) increases slightly with increasing the temperature. However, it is almost independent of the pressure and voltages.

Fine lithographic technology in a submicron design regime is necessary for the fabrication of VLSI circuits. In such lithography, fine pattern delineation is performed by electron beam, ion beam and X-ray lithography instead of photolithography. Therefore, the new resist materials and development method have been required. So, we are investigating another positive E-beam resists which have high sensitivity and dry etching resistance, Plasma co-polymerized resist was prepared using an interelectrode gas-flow-type reacter. Methymethacrylate, tetramethyltin and styrene were chosen as the monomer to be used. The delineated pattern in the resist was developed with gas-flow-type reactor using an argon and 02 as etching gas. We studied about the effects of discharge power and mixing rate of the co-polymerized thin :film. The molecular structure of thin film was investigated by ESCA and IR, and then was discussed in relation to its quality as a resist.

In the field of the optics, precise machine, semiconducting processing, the micro-positioning actuators are required for the control of position in the submicron range. In this study, PNN-PZN-PZT ceramics were fabricated by solid state reaction. The structural, dielectric and electric properties were investigated for sintering condition. The specimen sintered for 1hr at 1,150($^{\circ}C$), had the highest density and dielectric contant.

A study on $BaTiO_3$ ceramics have been shown that dielectric properties of $BaTiO_3$ ceramics strongly depend on the size and ferroelectric domain density of the constituting grain. According to rising substrate temperature from $25[^{\circ}C]$ to $600[^{\circ}C]$, the peak intensity and crystal plane in XRD are increased. In this study, $BaTiO_3$ thin film prepared by RF sputtering from room temperature to $600[^{\circ}C]$ of substrate temperature. Therefore, we tried to investigate the relation between the characteristics of ceramics structure and dielectric factor.

In the structure of ZnO/nip-SiC: H/metal substrate amorphous silicon (a-Si:H) solar cells, the effects of inserting a rear textured ZnO in the p-SiC:H/metal interface and a graded bandgap buffer layer in the i/p-SiC:H have been analysed by computer simulation. The incident light was taken to have an intensity of $100mW/cm^2$(AM-1). The thickness of the a-Si:H n, ${\delta}$-doped a-SiC:H p, and buffer layers was assumed to be $200{\AA},\;66{\AA}$, and $80{\AA}$, respectively. The scattering coefficients of the front and back ZnO were taken to be 0.2 and 0.7, respectively. Inserting the rear buffer layer significantly increases the open circuit voltage($V_{oc}$) due to reduction of the i/p interface recombination rate. The use of textured ZnO markedly improves collection efficiency in the long wavelengths( above ${\sim}550nm$ ) by back scattering and light confinement effects, resulting in dramatic enhancement of the short circuit current density($J_{sc}$). By using the rear buffer and textured ZnO, the i-layer thickness of the ceil for obtaining the maximum efficiency becomes thinner(${\sim}2500{\AA}$). From these results, it is concluded that the use of textured ZnO and buffer layer at the backside of the ceil is very effective for enhancing the conversion efficiency and reducing the degradation of a-Si:H pin-type solar cells.

The method of passivation for protecting the $Hg_{l-x}Cd_xTe$ surface is important device fabrication process, because the surface components are highly reactive leading to its chemical and electrical instability. Especially, the material of which composition is x=0.2 or 0.3, is narrow bandgap semiconductor and used as detector of infrared radiation. The device performance of narrow bandgap semiconductors are largely governed by the properties of the semiconductor surface. The electro-chemical processing of $Hg_{l-x}Cd_xTe$ allows rigorous control of the surface chemistry and provides an in-situ monitor of surface reaction. So electro-chemical reduction at specific potential can selectively eliminate the undesirable species on the surface and manipulated to reproducibly attain the desired stoichiometry. This method shows to assess the quality or chemically treated $Hg_{l-x}Cd_xTe$ good surface.

A three-layered piezoelectric ceramic transducer is fabricated with three piezoelectric ceramic disk transducers and two sheets of thin insulator. Its equvalent circuit is derived from the Mason's model of a thickness-driven piezoelectric transducer. We applied the electric input near its fundamental resonant frequency to the center transducer and connect the output voltages across the left and right transducers in series to the resistor load. Then we investigate the load characteristics at resonant frequencies under various resistor loads and the frequency characteristics near the resonant frequency under no load. Moreover, symbolic expressions for input impedances, voltage ratios, resonant frequencies, and bandwidths have been derived. The values calculated from those symbolic expressions are shown to agree well with the measurement values.

Methods are described for the design and fabrication of the sensor circuits on the polarographic oxygen sensing electrodes. The discussion includes: a method for the +5V single-supply driving for the sensor circuits, a method of low power comsumption for the front-end electronics. Typical polarograms for the commercial DO probes using this sensor circuits are presented. High accuracy of the I to V conversion using the circuits is verified.

Dielectric properties of $C_{22}$-Quinolium(TCNQ) Langmuir-Blodgett (LB) films were studied as a function of frequency(10Hz-13MHz) and annealing temperature($20{\sim}240^{\circ}C$). A complex dielectric constant ${\epsilon}^*={\epsilon}'-i{\epsilon}"$, in general, shows the frequency dependence of orientational polarization in the measured frequency range. A dielectric permittivity ${\epsilon}'$ at 10Hz is around 8.2 and decreases very slowly as the frequency increases up to 1 MHz, and then suddenly drops above this frequency, while a dielectric loss factor ${\epsilon}"$ reaches a maximum near 1 MHz. Its annealing temperature dependence at 10Hz shows that ${\epsilon}'$ and ${\epsilon}"$ increase as the temperature increases upto $180^{\circ}C$, even though there is a little drop near $120{\sim}160^{\circ}C$. Both ${\epsilon}'$ and ${\epsilon}"$ drop quickly above $180^{\circ}C$. which may be thought of a destruction of the LB films. Another fact of the annealing temperature dependence of the dielectric constant is an occurrence of the new dielectric dispersion below 100Hz. This low frequency dispersion is getting clear above $80^{\circ}C$.

With the contact angle of phase epoxy resin on the inorganic filler(glass plate) surface treated with air plasma, we have studied about the interface between epoxy resin and glass plate as simple model of a glass fiber reinforced composite materials. The contact angle on the inorganic filler surface varied with surface treatment conditions. The contact angle significantly depends on plasma treating time and environment temperature of the oven.

At 34 at% Co-Fe, the aluminum anodic oxidized (alumite) films of particle diameter $150{\AA}$ have large perpendicular anisotropy energy and high coercive force. However, for the samples of particle diameter larger than $450{\AA}$, the bottom of each particle forms abnormal part called branch-shaped different from that of particle diameter $150{\AA}$. In this case the magnetic anisotropy energy Ku was about zero at the compositions of 45 and 75 at% Co. Furthermore, at tile compositions from 50 to 70 at% Co, the values of Ku became negative value. We confirmed that Fe-C deposited the bottom of particle orients very strongly and it has a large influence upon the magnetic anisotropy energy.

An ability of $NO_2$ gas detection has been investigated using dilithium phthalocyanine($Li_2Pc$) Langmuir-Blodgett (LB) films. It is a well-known gas sensitive material and has been manufactured under a surface pressure of 30mN/m. A status of deposited films was confirmed by UV-visible absorption spectrum, ellipsometry measurements and current-voltage characteristics. Gas-detection characteristics of the films were studied through an electrical conductivity, response time, recovery time, and reproducibility under 200 ppm of $NO_2$ gases.

ZnO transparent conducting oxide thin films have been prepared by Pyrosol deposition method. The effect of the Al doping with varying Al/Zn mole ratio and the post-deposition heat treatment on the electrical resistivity and optical transmittance of the prepared films have been investigated. From the experimental results, the ZnO:Al thin films with resistivity as low as $3{\times}10^{-3}{\Omega}cm$ and transmittance as high as 80% can be obtained by Al doping. Also We have found the annealing of the as-deposited ZnO film in vacuum leads to a substantial reduction in resistivity without affecting the optical transmittance and crystallographic orientation. However, the annealing effect of ZnO:Al thin films is smaller than ZnO films with respect to reduction in resistivity.

9/65/35 PLZT thin films were prepared by sol-gel processing and annealed by direct insertion, 9/65/35 PLZT thin films were poly-crystallized after direct insertion at $750^{\circ}C$ for 3omin. The grain size of film was 50 nm, coercive field was 28.2 kV/cm and remnant polarization was $3.68 {\mu}C/cm^2$.

The electrochromism of $WO_3$ and $V_2O_5$ thin films have been studied. The $WO_3$ thin film is found to be cathodic coloration material and the coloration efficiency of this film is close to $60 [cm^2/C]$ in the near infrared region. The $V_2O_5$ thin film exhibits cathodic coloration in tile near infrared and anodic coloration in the blue and near UV region. The cathodic coloration in the $450{\sim}1100 nm$ wavelength range is relatively weak with a maximum coloration efficiency of $6 [cm^2/C]$).

The development of an insulated coating which can be used for amorphous alloys is extremely important from the practical point of view. This importance may be enhanced by the influence of the coating on the magnetic properties. The aim of the study is to show how some coating influence the magnetic properties of $Fe_{87}Zr_7B_5Ag_1(at%)$ amorphous alloy.

$0.36[wtx]Sio_2$ and $0.1[wtx]H_3BO_3$ were added to strontium ferrite magnets of the magnetoplumbite phase SrO $5.7Fe_2O_3$. This experiment was carried out to investigate the effects of particle size distribution as a function of milling time(20,30,40,50,60,70 hours) on the magnetic properties of SrO $5.7Fe_2O_3$ ferrite magnet. The B-H Curve, density and the degree of orientation were measured. The optimal conditions of making magnets and properties of a typical sample are the following : The milling time was 60 hours. Magnetic and physical properties are $B_r$=4000[G], $_BH_c$=3330[Oe], $_IH_c$=3525[Oe], (BH)max=3.786 [MGOe], density= $5.0063g/cm^2$, orientation factor f=0.813.

The thermal properties of Cordierite$(2MgO.2Al_2O_3.5SiO_2)$ + 30 [wt%]clay + X[wt%]MnO_2$ of infrared radiator have been investigated as a function of $MnO_2$ additives (X=0, 0.1, 0.25, 0.5, 1.0, 1.5, 2.0, 2.5). The thermal expansion coefficient was decreased and the spectral emissivity was increased only in the below $4.5{\mu}m$ wavelength with increasing amaunts(wt%) of $MnO_2$ additives. Also, the infrared radiator of Cordierite system which spectral emissivity was approximately 1.0 can be attainable at from $4.5{\mu}m$ to $8{\mu}m$ wavelength. The spectral emissivity was decreased from $8{\mu}m$ to $14{\mu}m$ at X=2.5.

Photoisomerization characteristics of 4-octyl-4'-(5-carboxy-pentamethyleneoxy) azobenzene molecules (8A5H) were attained by measurement of absorbtion spectra. 8A5H in chroloform($6.0{\times}10^{-5}[M/l]$) shows trans to cis and cis to trans isomerization by irradiation of lights of 360[nm] and 450[nm] wavelength. From LB monolayer films of 8A5H, also the cis/trans photoisomerization was obtained and it has reversibility and memory characteristics. We are now trying to detect these properties of 8A5H electrically. On this paper, we investigated the structural changes of monolayer on the water surface by measuring the displacement current as a preliminary experiment. The measuring system was constructed at home-made Kuhn type LB(Langmuir-Blodgett) deposition apparatus. 8A5H solution was spreaded at the air-water interface and the currents induced by the dynamic behavior of molecules were measured when the molecules were pressed by barrier. The reversibility of displacement currents by compression and expansion was obtained from 8A5H molecules, which shows the compressed molecules have a tendency to disperse after the compression. From this experiment, we conclude that the behavior of molecules on water surface can be monitored electrically by using this current measuring method, and this method can also be applied to detect the photoisomerization of monolayers on water surface.

the application of epoxy composite materials for outdoor insulating systems has some significant advantages compared with conventional inorganic materials, that is low weight in combination with high mechanical strength, small dimensions and design versatility. The experimental results for the basis composition and interlace characteristics of the matrix resin/inorganic fillers($SiO_2$) which are the composite materials have been studied. The electrical characteristics(electrical breakdown, dielectric, insulating resistivity, tracking) and mechanical characteristics( tensile strength, elongation, flexible strength) in the epoxy composite materials have been studied. The life of the epoxy composite material was evaluated by accelerated Weather-Ometer test and the degradation process due to outdoor exposure condition is discussed with respect to the mechanical and electrical properties.

In this paper, We treated the electrical characteristic of fluorocarbon. We found that its properties - dielectric properties, resistivities, dielectric characteristics. etc - are sufficient to use as coolants for GAS INSULATED TRANSFORMER.

In order to investigate the properties of electrical conduction and space charge in crosslinked polyethylene film, we were observed the specimen with 200[${\mu}m$] thickness. The electrical conduction properties of specimen were measured temperature range from 30 to $110[^{\circ}C] $as well as $10^{-2}$ - 1 [MV/cm] of electric field. The investigations on influence of space charge were carried out at room temperature and $60 [^{\circ}C]$.

The nitrification of pure iron powders is found to occur even at room temperature by high energy ball milling in $NH_3$ gas atmosphere. The powders of metastable iron nitrides ($0<at.%N{\le}23.3$) thus produced are identified as the super-saturated bee structure for the N content below 14.9 at.%N and the high temperature phase of the hcp structure above 19.4 at.%N. The atomic volume of Fe in the bcc phase is found to be smaller than that of the N-martensite reported in the literature. Magnetization at room temperature gradually decreases with increasing the N concentration in contrast to the enhancement reported for the bet nitrides. Neutron diffraction experiment also provide detailed information about the local structure surrounding the nitrogen atom. The coordination number of Fe atom around a nitrogen atom for the iron nitride containing 9.5 at.%N turns out to be 3.9 atoms.

Cell fusion device is an artificial equipment which fuses electrically two types of cells fed from the respective micropump to the fusion chamber by electric pulses. In this case, the detective sensor of flowing cell, along with passage, is required to control the time of pulses applied to cell and the injection of cells which are fed from inlet to micropump. There are two methods of detection of flowing cell; optical, impedance method. The difference of output for optical sensor is about 426mV for 805nm wavelength. about 37mV for 665nm wavelength. In impedance method, sensor output is 132.33mV at middle point and 117.10mV at edge point in the channel. Experimental results show that the optimal frequency range of sensor output is Iron 50Hz to 400Hz.

In this paper, the flow velocity/mass sensor which is based on the principle of CCT(Constant Chip Temperature) and its digital operating circuit and system have been developed and tested. The experimental result for flow velocity shows that the sensitivity is $644.01{\mu}W^2/[m/sec]$ for air, and there is nearly no hysteresis for full measured range of velocity. Response tine is between 1 second and 8 seconds for low and large velocity variation, respectively.

Silver-Nickel alloy has been used as a electrical contact material for low voltage, low current. Since the solubility between Ag and Ni is very low, it is difficult to produce Ag-Ni alloy by using conventional melting method and disperse Ni powder homogeneously in Ag matrix. In this study we have been produced fine Ag-Ni alloy powder by using coprecipitation method. Firstly, we have produced silver-nickel nitrate solution by dissolving the Ag and Ni ingot in nitric acid solution and then, coprecipitate (Ag, Ni)carbonate dropping Ag-Ni nitrate solution to sodium carbonate solution. (Ag, Ni) carbonate is heat-treated in $H_2$ atmosphere, $400^{\circ}C$ and it has been analysed by TGA, SEM, XRD, ICP. It is represented Silver-Nickel alloy powder in the particle range of $0.1{\sim}0.5{\mu}m$.

High frequency Magnetic Properties of amorphous $Fe_{78}B_{13}Si_9$ ribbon were studied. Squareness ( Br/Bs ) and coercive force ( Hc ) of the specimen field annealed at $380^{\circ}C$ for 2 hrs are changed with the tension and the measuring frequency. So, we could optimise the tension having good magnetic properties at a certain frequency.

In this study, various nozzle of ultrasonic spray were designed by using Langevin type electrostriction transducer. The electrical and dynamic characteristics of ultrasonic nozzle with various horn type were investigated. We obtained the average particle size and size distribution profiles with output frequency.

High strengh pocelain insulators with 35wt% alumina were manufactured by wet produce technique. The microstructure and crystalline phases of this samples and the effect of CaO addition to insulator bodies were studied. Electrical and mechanical properties (permittivity, dissipation factor, modulus of rupture, Young's modulus etc,) were studied. The relation between microstructure and electrical, mechanical properties were analyzed.

In order to protect cable from rat's biting, a development of rodent repellent is described. This cable has double coated sheath such as construction of skin layer over the conventional cable sheath. Stabilized rodent repellent agent which has good compatibility with PVC is employed in a skin layer. Rodent repellent layer has highly residual properties of agent through the manufacturing process, and meets the general requirements of cable sheath. Also, rat repellent effect is excellent.

In this study, in order to improve the problem that dielectric breakdown strength decrease remarkably at high temperature, simultaneous interpenetrating polymer networks method was Introduced so that epoxy insulating material could have stable temperature characteristics and stable dielectric breakdown characteristics at whole temperature range. So network structure of epoxy/$SiO_2$ composite material was changed by adding MA and MA/PU into epoxy resin. DC voltage is applied into the specimen fabricated by this method, and then the result was compared and investigated.

Epoxy resin insulator have good electrical properties (high electric strength, high resistivity, low dielectric loss) in addition to high mechanical strength, small dimensions and design versatility. Polymer insulator, however, are subjected to aging processes, caused by the surrounding atmosphere, which may lead to degradation of their properties. This paper describes the results of a important study on the artificial pollution test, Weather-Ometer properties and rotating wheel dip test of high voltage different aging insulators which are the most important factors for outdoor uses. Also, the objects of this paper are to (a)result of insulator under dry(wet) flashover voltage, (b)artificial pollution test of salt spay, (c)Accelerated aging test of Weather-Ometer, (d) wet and dry flashover voltage under rotating wheel dip test.

In this paper, the monolayers of the polymers which polyion-complexed with PAA at the air-water interrace can be transferred on to solid substrates such as porous fluorocarbon membranes filter and quartz crystal microbalance. The properties of the monolayers and the LB films investigated by ${\pi}-A$ isotherms, FT-IR, DSC, deposition ratio, QCM, and SEM will be discussed. In addition, it was attempted to investigated the surface characterics of polymer/metal compound LB films in the air/water interface.

Recently composite insulators have been In the spotlight because they have many good characteristics as a outdoor insulator for high voltage. The long term properties in composite insulator depend on shed materials. Silicone rubber out of some candidates of shed material has been obtaining good credit from the long term test in field.

Power transformer has been expected to work with safety and reliability during the long period over 30 years. Pressboard has been effectively used as the insulating materials of transformer and they seem to be used as in insulating materials of transformer. This paper describes the results of a basic study on the electric strength, resistivity, permittivity and dielectric loss properties of pressboard to be made with some kinds of pulp and different waters.

We now expect the various dispersed generation system installation to the power distribution system in a unexpected manner. If so, the power utility may experience the several unexpected problems such as voltage variation, harmonic distortion etc. In order to test the various phenomena related to the fault, we developed the fuel cell simulator and fault simulator. Several kinds of fault cases are tried. Test results and analysis are shown in this paper.

Azobenzene derivative is so stiff that monolayer cannot be formed on the subphase. To form a monolayer on the subphase, azobenzene derivative was mixed arachidic acid. It didn't form a monolayer, either. The mixture of azobenzene derivative and L-${\alpha}$-phosphatidylcholine generated a monolayer on the wafer subphase. Thickness of LB film layered at 30 mN/m was about $70{\AA}$. The polarized UV-visible absorption spectra of the mixture exhibited a dichroic ratio of azobenzene derivative and L-${\alpha}$-phosphatidylcholine.

In order to investigate the effects of crystal structure in electrical breakdown of polyethylene film. Low molecular materials in polyethylene are removed by the method as follow. Polyethylene was dissolved in xylene and filtered through a glass fiber filter. And then, a polyethylene thin films of thickness $0.5 - 0.9{\mu}m$ are prepared with heat treatment from solution casting. To evaluate the performance of PE film, Electrical breakdown of PE film are measured on M( Al) - I (PE)-M(Al) system.

Description is given of the effect of fuse-element notch shape on interruption parameters. The notch of fuse-elements have all the same area. Tests were carried out at direct current and carried out the effect of the fuse element construction on the process of interrupting short circuit and overload current. The arcing phenomenon in a low voltage fuse operation in case of high current value of short circuit is analyzed.

For the development of the 25.8kV outdoor GCB (Gas - Circuit - Breaker), which have a surge surpression performance in closing & opening of circuit and a high reliability performance, we have developed the 25.8kV gas bushing first of all in KOREA. After manufacturing of 25.8kV/2000A gas bushing, we carried out the dimension & visual test and electrical & mechanical test and we have got the favorable test-results. And it was put together real outdoor GCB, and then we carried out type test at KERI and have confirmed the performance of this bushing.

A polyimide-based capacitive humidity sensor has been designed and fabricated using silicon integrated-circuit technology, and its performance measured. The sensor showed excellent linearity, low temperature coefficient, and low hysteresis over a wide range of relative humidity and temperature. The signal conditioning circuits for detecting relative humidity and converting it to voltage have been developed based on a charge redistribution between capacitors using switched -capacitors.

A silicon microbridge flow sensor has been developed. The heat transfer within silicon microbridge is modeled to predict the characteristics of the sensor. The flow sensor shows high sensitivity at small flow rate. This device is simple to fabricate, using standard IC and micromachining technology.

Polyimide thin films were fabricated an using vapor deposition polymerization apportus, and their FT-IR and TGA characteristics were investigated. The peaks of $720cm^{-1}$ and $1380cm^{-1}$ show C=O stretch mode and C-N stretch mode, and that of the cured polyimide at $350^{\circ}C$ were sturated. $T_d$(Depolymerization temperature) was showed at $405^{\circ}C$ from research of thermal resistivity characteristics by TGA It was possible to fabrication of polyimide thin film by VDPM.

The purpose of this study is to measure the electrophotographic characteristics of double-layered organic photoreceptor made by dip-coating method, and to evaluate an application for the laser beam printer drum. From the result, electrophotographic characteristics of the photoreceptor were depend on the thickness of the CTL and the initial surface potential.

Plasma polymerized thin films was prepared using an interelectrod inductively coupled gas-flow-type reactor. Styrene was chosen as the monomer to be used. This thin films were also delineated by the electron-beam apparatus with an acceleration voltage 30kV, and the pattern in the resist was developed with RIE 80 with argon gas mixture ratio, pressure and RF power. The molecular structure of thin films was investigated by GPC and FT-IR and then was discussed in relation to its quality as a resist. In the case of plasma polymerization, thickness of resist could be controlled by discharge duration and power. Also etch rate is increased as to growing pressure with RIE 80.

In this study, the piezoelectric transducers with 1-3 connectivity have maded. A piezoelectric ceramic PZT prepared by Wet-Dry Combination method is used as a filler in Eccogel polymer matrix. The pulse-echo response for 1-3 type composite transducers were carried out in water. It was observed that the transmitting and receiving sensitivity of 1-3 type composite transducers were improved in comparison with that or solid PZT transducer. The reason is for that 1-3 composites have a hish piezoelectric voltage coefficients, The period of pulse-echo response for the transducer is in a good agreement with the resonant frequency of self-maded composite transducer.

In recently, there is growing demand for microwave absorbing matrial, and for the design method of microwave absorber. We developed a new method to design the matching frequency and matrial thick for ferrite/rubber composite absorber. Ni-Zn ferrite prepared with coprecipitation was compounded with silicon rubber, and, subsequently, pressed to ring specimen. The matrial constant of the ferrite/rubber composite absorber was used to design the matching frequency and matrial thick with matching map. In this study, we could predict matching condition from the design method. Foremore, using matching boundary map, we could also predict the condition of over 20[dB] attenuation.

The electrodes for Phosphoric Acid Fuel Ceil were fabricated as a condition of PTFE contents in electrocatalyst layer and sintering temperature in the range of 25 -- 65 wt% and 310 -- $390^{\circ}C$, respectively. For the fabricated electrode, the accelation testing of cathode half cell at open circuit potential was investigated. While the performance of electrode showed maximum at the low level of PTFE contents in the initial stage of accelation testing, the maximum performance was shifted to higher PTFE contents of 45wt% after 24hrs accelation testing.

A novel magnetotransistor using a separated drift field with the guard ring around the emitter has been designed and fabricated. The operating principle of the proposed magnetic field sensor is based on the emitter injection modulation. The $p^+$ guard ring around the n-type emitter confines drifted electrons in the emitter, hence the induced Hall voltage in the emitter is increased. The measured relative sensitivity of the separated drift magnetotransistor with the guard ring is about 100 times larger than that without the guard ring.

Expressions for the displacement of a bimorph, one end fixed and the other free, has been introduced when sinusoidal inputs were applied to the ceramic plates on a thin metal plate. Maximum displacements at the free end and strains at the position of strain gage attached were measured when various wave forms, voltages, and frequencies were applied to the bimorph whose length is 6.6[cm], width 2.5[cm], and thickness 0.0365[cm]. Under the constant voltage ( $70[V_{peak}]$ ), the strains and the displacements at the free end were larger than the case of the sinusoidal input when the square wave was applied and were smaller when triangular wave. It was shown that the displacements at the free end and the strains of the gage position were increased as the applied voltage in the range of $30-90[V_{peak}]$ and effective length were increased. And it was also found that the resonant frequency of a bimorph was decreased as its effective length was increased, and that the displacements and the strains were maximum at the resonant frequency.

The method of suppression based on the principle of energy trapping effect is very effective at high frequency. In this paper, We intended to get resonant frequency and bandpass filer characteristics in appling to vibration mode of PZT-4 and PZT-8 using trapped energy phenomenon. First, we theoretically analyzed a piezoelectric ceramic filter characteristics changing the thickness of ceramic plate, electrode spacing and distance between the two pairs of electrodes. We also experimentally investigated characteristics of ceramic filter made.

This paper deals with piezoresistive humidity sensor using polycrystalline silicon (Poly-Si ) with membrane in sensors of semiconductor. Poly-Si piezoresistors which have no temperature dependancy are deposited on silicon wafer, membrane is formed with micromachining technology, then polyimide is formed as a hygroscopic layer. Whereas the principle of conventional humidify sensors are based on the change in electrical properties of the material, the humidity induced volume change of a polyimide layer leads to a deformation of a silicon membrane in this case. This deformation is transformed into an output voltage by Poly-Si piezoresistive. Wheatstone bridge. Fabricated piezoresistive humidity sensors showed good linearity, response time, and long term stability.

Laser ablation of glass substrates (8K-7 and synthetic quartz) using a transversely excited atmospheric (TEA) $CO_2$ laser has been inverstigated to obtain high speed etching. The ablation occurs by local heating of a substrate with a focused TEA-$CO_2$ laser beam. The dependence of ablation rate on pulse count and repetition-rate of laser has been discussed.

The accumulation of space charge in PE/PE/PE laminates was investigated using the low density polyethylenes having different melt indices from 0.25 to 45 g/10 min. Both heterocharge and homocharge accumulated in parent polyethylenes depend on the value of melt index. A general rule found in this study was that the heterocharge decreases as the melt index increases and finally the homocharge accumulates when the melt index is very high. Because of this reason, PE laminates showed different charge formation characteristics depending on melt index of polyethylene. Details of up to date results are described in the text.

The annular induction electromagnetic pump with maximum flowrate of $60{\ell}/min$ for the sodium coolant system of liquid metal fast breeder reacters has been designed using the equivalent circuit method. The final optimum values of geometrical and electromagnetic parameters were obtained for an annular induction pump from the relation of the electrical variables giving the developing force to the fluid and the pressure drops between both sides of the pump. The physical properties of the core, coil condoctor materials in the high temperature and pump cooling systems under operation have been taken into account in the design of the pump. The structural material were also selected considering the reaction with sodium and the magnetic field distortion.

The effects of Ge composition variation in $a-Si_{1-x}Ge_x:H$ alloy p-i-n solar cells on the physical properties and current density-voltage characteristics are analyzed by a new simulation modelling based on the update published experimental datas. The simulation modelling includes newly formulated density of gap density spectrum corresponding to Ge composition variation and utilizes the newly derived generation rate formulars which include the reflection coefficients and can apply to multijunction structures as well as single junction structure. The effects in $a-Si_{1-x}Ge_x:H$ single junction are analyzed through the efficiency, fill factor, open circuit voltage, short circuit current density, free carriers, trap carriers, electric field, generation rate and recombination rate. Based on the results analyzed in single junction structure, the applications to multiple junction structures are discussed and the optimal conditions reaching to a high performance are investigated.

This paper propose a new $Ta_2O_5$ film fabrication technique by Laser CVD. Laser CVD is noticable that film formation can be done at low temperature with less damage. After film deposition, the characteristics of Laser CVD $Ta_2O_5$ film is evaluated.

The short channel poly-Si TFT is important in aspect of transistor characteristics, packing density and aperture ratio. In this paper, we have reported the degradation phenomena of short channel poly-Si TFT's which had significantly degraded device parameters, such as threshold voltage shift and a great asymmetric degradation, due to gate and drain electrical stress. The reduced effective channel length and expanded depletion region may be the main reason of these significant device parameters.

This paper deals with the edge effect in thin insulating films, focusing on their dependence on film thickness, so we derived a simple mathematical form which depicts that reducing film thickness lowers the field at the electrode edge. we expect that this result may be suitable to problems with multi level insulating films.

The breakdown voltages of punchthrough-mode diodes with cylindrical junction are analytically calculated, The proposed method, which is based on th Gauss's law, estimates the lateral expansion of the depletion region as well as the electric field and the charge distribution. The proposed method is given in terms of epitaxial layer width, the epitaxial layer doping concentration, and curvature radius of the junction edge. The calculation results agree well with the MEDICI simulation results for various device parameters.

A monolithic current limiting power MOSFET, which may be easily fabricated by the conventional DMOS process, is proposed. The proposed current limiting MOSFET consists of main power cells, sensing cells, and NPN lateral bipolar transistor so that users can adjust the current limiting levels with only one external resistor. The behaviors of the proposed device are numerically simulated and analyzed by 2-D device simulator MEDICI and mixed-mode simulator CA-AAM(Circuit Analysis Advanced Application Module).

$Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramic thin films were fabricated from an alkoxide-based solution by Sol-Gel method. $Pb(Zr_{0.52}Ti_{0.48})O_3$ ceramic thin films were formed by spin coating method on $Pt/SiO_2/Si$ substrate at 3000rpm for 30 seconds. The coating process was repeated 6 times and then heat-treated at temperature between 500 - $800[^{\circ}C]$ for 1 hour. The final thickness of the thin films were about 4800[A]. The 100% ferroelectric perovskite phases precipitated under the heat treated at $700[^{\circ}C]$ for 1 hour. $Pb(Zr_{0.52}Ti_{0.48})O_3$ thin films heat-treated at $700[^{\circ}C]$ for 1 hour showed good dielectric constant (812) property.

A surface acoustic wave(SAW) sensor for the detection of odorants has been constructed by depositing various phospholipids and fatty acids onto the surface of the SAW device. Applying the Langmuir-Blodgett technique, it was possible to deposit the optimal number of layers which was found to be between 10 and 20. Menthone, amylacetate, acetoin, and other organic gases showed different affinities to the coated lipids. An explanation is given for different odorant affinities based on the monolayer properties of phospholipids.

BiCMOS is the newly developed technology that integrates both CMOS and bipolar structures on the same integrated circuit. Improved performance can be obtained from combining the advantages of high density and low power in CMOS with the speed and current capibility advantages by bipolar. However, the major drawbacks to BiCMOS are high cost, long fabrication time and difficulty of merging CMOS with bipolar without degrading of device Performance because CMOS and bipolar share same process step. In this paper, N-Well CMOS oriented BiCMOS process and optimization of device performance are studied when N-Well links CMOS with bipolar process step by 2D process and 3D Device simulation. From the simulation, Constriction of linking process step has been understood and provided to give the method of choosing BiCMOS for various analog design request.

The electrical characteristics of $Al/Ta_2O_5/Si$ metal-oxide-semiconductor (MOS) capacitors were studied. $Ta_2O_5$ films on p-type silicon had been prepared by ionized cluster beam epitaxy technique (ICBE). This $Ta_2O_5$ films have low leakage current, high breakdown strength and low flat band shift. In this research, a single crystalline cpitaxial film of $Ta_2O_5$ has been grown on p-Si wafer using an ICBE technique. The native oxide layer ($SiO_2$) on the silicon substrate was removed below $500^{\circ}C$ by use of an accelerated arsenic ion beam, instead of a high temperature deposition. $Ta_2O_5$ films formed by ICBE technique can be received considerable attention for applications to coupling capacitors, gate dielectrics in MOS devices, and memory storage capacitor insulator because of their high dielectric constants above 20 and low temperature process.

In this paper Dielectric and strain properties of (1-x-y)PMN-yPT-xST Ceramics have been investigated as a function of the amount of $SrTiO_3(ST)$. The $SrTiO_3$ content is ranged from 0.01-0.06(wt%). As the amount of ST is increased, dielectric constant has a maximum value at 0.05 mol composition. The Curie temperature is decreased linearly with increasing ST composition and Polarization properties have been investigated. Coercive field and ramnant polarization has a maximum value at 0.01mol composition.

This paper describes the structure and electrical characteristics of a shorted anode p-i-n switch. The device showed a significant improvement in the threshold voltage-to-holding voltage ratio, which is due to the suppression of the hole injection from the anode and to the gold gettering at the anode side. The shorted anode devices with a $100{\mu}m$ channel length have a threshold voltage of 300 volts and a holding voltage of 5.5 volts.

In this paper, $TiO_2-V_2O_5$ thin films are fabricated by Sol-Gel method and their humidity-sensing characteristics have been investigated. The microstructure of specimen is porous. The humidity-sensing characteristics of thin films are good according to increasing heat treatment temperature and decreasing measurement frequency.

Porous piezoelectric ceramics of PZT have been newly developed to apply for ultrasonic transducers. The porous PZT was prepared from a mixture of PZT and polyvinylalcohol (PVA) powders by BURPS(Burnout Plastic Sphere) technique. Porous PZT bodies were shown a homogeneous microstructure consisting of 30 - 80 (${\mu}m$) pore size in sintered PZT bodies. The dielectric and piezoelectric properties on various PVA wt.% have investigated.

In this paper, the microwave absorption properties of two layered absorber were evaluated. The two layer absorber were composed of Ni-Zn ferrite/rubber absorber and Ferroxplana/rubber absorber. The most absorption properties condition were obtained when the transforming layer and absorbing layer were Ferroxplana/robber absorber and Ni -Zn ferrite/rubber absorber. respectivity. The optimal thickness of the transforming and the absorbing layer were 4(mm) and 1(mm), respective1y.

The dielectric and electrical properties of $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3-BaTiO_3$ have been investigated. Perovskite crystalline phase of the specimens is confimed by XRD. The curie temperature decrease with increasing $BaTiO_3$ and hysteresis phenomena decrease with increasement of $BaTiO_3$. The strain vs. applied voltage characteristics exhibit nonlinear relationship and the specimen. of 0.9PMN-0.08PT-0.02BT shows the largest strain.

In this paper, we performed theoretical computer calculation for ion-exchange embedded channel waveguide using Field Shadow Method. Using the parameters of ${\Delta}n=0.09$, 0.009, $w=8{\mu}m$. d=8.854, $8.189{\mu}m$ we decided the waveguide characteristics. The dispersion curves showed the optimal fabrication conditions of the waveguides. We observed each of the 3-D field distributions in the various waveguides.

$(Zr_{0.65}Sn_{0.35})Ti_{1.04}O_4$ system which has a dielectric constant, low dielectric loss and temperature coefficient was investigated. Temperature coefficient varied from positive to negative with increasing of NiO. For the NiO content 1.0wt%. i.e $(Zr_{0.65}Sn_{0.35})Ti_{1.04}O_4$, the ceramic showed very good dielectric properties such as ${\epsilon}$=37.8, $Q{\times}f_o=49.000$ and ${\tau}_r= 4{\pm}1ppm/^{\circ}C$.

Diamond thin films were deposited on Si substrate from $CH_4-H_2-O_2$ system by MWPECVD at the condition of power of 800W, pressure of 80torr, $H_2$ flow rate of $75{\sim}81sccm$, $O_2$ flow rate of $0{\sim}3.8sccm$, $CH_4$ flow rate of $4.8{\sim}9sccm$, substrate temp, of $950{\sim}1010^{\circ}C$ and deposition time of 5hr. The deposited films were characterized by SEM, XRD and Raman spectroscopy. The growth rates of thin films and particles was measured. Good quality were synthesized at 40% of oxygen concentration which 6% of fixed metane concentration, and at 50%. Its deposition rates were $2.4{\mu}m/h$ respectively. As oxygen concentration increased, it was known that the broad peak of $1350 cm^{-1}$ was shifted to $1332cm^{-1}$ due to etching of carbon component.

Study on the effect of hydrogen flow rate and $CH_4$ concentration in deposition of the diamond thin films by MWPECVD diamond thin films were deposited on Si substrate from $CH_4-H_2-O_2$ system by MWPE CVD, and identified by SEM, XRD and Raman spectroscopy. The flow rate of hydrogen didn't affect the surface morphology and crystallity of diamond thin films, but did slightly affect growth rate. When the concentration of oxygen was fixed at 40%, the growth rate and crystallity of diamond thin films were gradually improved according to increasment of concentration of $CH_4$ but growth rate of the thin films showed peak at 7% and the crystallity showed peak at 6%.

In this study, x PSN - y PT - z PZ ceramics doped with w $MnO_2$ were fabricated by the mixed oxide method at 1250 [$^{\circ}C$] for 2[hr] and then the dielectric and pyroelectric properties were investigated. In the 0.05 PSN - 0.4 PT - 0.55 PZ specimen with 0.5[wt%] $MnO_2$ the Pyroelectrics coefficient was $6.6{\times}10^{-8}[C/cm^2.^{\circ}C]$, respectibly.

This paper studies on the outdoor field test facilities which are established for weather-resist and mechanical-resist property teat of composite insulator. We have established measuring and data acquisition system for various test conditions -leakage current, temperature, humidity, wind direction, wind velocity and rainfall. The merry-go-round test and salt fog test have been studied in order to evaluate non tracking property of rubber material. Especially we have checked the relationship between hydrophobicity and outdoor exposure degree by contact angle measurement.

Lately in KEPCO, the power plant capacity has increasingly become larger than before and it has become difficult to get R.O.W for T/L. Therefore KEPCO decided to increase its system voltage level from 345kV to 765kV. By doing this, KEPCO would like to expand its transmission capability by less T/L route. In 765kV system, we should consider various kinds of environmental impacts that can be neglected in lower voltage level. These environmental impacts are very important factor in T/L design. That can be changed greatly according to the selected conductor. And also conductor selection has relation with the economy of T/L construction directly. This paper deals with some general factors to be considered and basic principles about the conductor and ground wire selection for 765KV T/L with referring to the experiences of foreign utilities.

This paper calculates the induced voltage and current for a human and a car under 765 kV AC double circuit transmission line. A human and a car is simulated as two dimension by the use of charge simulation method and as three dimension by using surface charge method. The phase arrangement of transmission line is varied to calculate the induced voltage and current. In two cases a human and a car is grounded or floated, the induced voltage and current is also compared.

FLIC(Fluid in cell) method has been used for analyzing a cold gas flow field in an interrupter of a circuit treater since 1970s. In this paper FLIC method is applied to calculation of a cold gas flow and then combined with the simple are analysis method in order to investigate the flow field characteristics in a puffer type interrupter rated at 145kV 40kA. The results for a cold gas flow agree with the experimental measurement well. The other results such as pressure rise, arc temperature, post-arc current and so forth am also reasonable and show the possibility that the combined program can be applied to the design of UHV interrupters.

This paper describes electrical environmental study of a 765kV double circuit test line. Corona performance on several candidate conductor bundles has been investigated in the corona cage (single phase simulation facility) since 1984. We have known that six RAIL conductor bundle is the most suitable for the 765kV transmission Line, [3] To investigate electrical environmental impact of the future commerciale line, we build a full sacle 765kV test line in 1993. The test results of Audible Noise, Radio Interference, TV Interference from August, 1993 to Jan. 1994 were measured as $48.7[dBA](L_{50})$. $57.4[dB{\mu}V/m]$(Fair weather, $L_{50})$. $14.5[dB${\mu}$V/m]$(Fair weather, $L_{50}$). We have found that the Audible Noise data were very close to the predicted(48.5 [dBA]) by BPA Corona and Field Effects Computer program, however, the RI and TVI data were much higher than predicted(42 [dBmV/m], $7.9[dB{\mu}V/m)$ by the BPA program. We have investigating the reason of the difference. In the constructing of full scale test line, we developed the tubular tower, 765kV test transformer and hardwares of 765kV transmission line insulator strings. Also we will investigate the effects of plants under the 765kV test Line.

The clarification of insulation capability of GIS(Gas Insulated Substation) under very fast transient overvoltages such as disconnector/circuit-breaker induced surge is very important for establishing not only a rational insulation testing method, but also insulation design intending to make GIS more reliable and more minimized. One of the absolute prerequisits for this is that more accurate measurement of VFTO. This describes capacitive voltage measuring methods for high voltage steep-footed oscillating waves using capacitive coupling principle and their systems including source and load impedances. Time domain response of unit step and its frequency characteristics are also investigated.

This paper describes a proposed very fast transient overvoltages(VFTO) measurement system suited for established gas insulated switchgear(GIS). The detecting system consists of a shield electrode connected to a buffer amplifier, and the transmission of the detected signal to an oscilloscope is made through an optical fiber. The bandwidth of the measurement system is 5 Hz to 30MHz. When determining the voltage dividing ratio by use of the commercial frequency voltage, the error is less than 0.5 %. Also, the data were obtained by the electric field probe and the high voltage probe, and their deviation for voltage dividing ratio were less than 1 %.

In hydro-generator, a groundwall insulation of stator windings gradually deteriorates due to mechanical, thermal, electrical and environmental stresses. These stresses combine to result in loose windings, delamination of the stator insulation and/or electrical tracking of the end winding, all of which can lead to stator insulation failures. Conventionally, off-line tests such as partial discharge measurement, DC/AC current test and ${\Delta}tan{\delta}$ test has been used for estimation of winding condition. However, off-line test requires large power supply and generator outage. In addition, major cause of insulation problems such as loose wedges and slot discharges may not be found with off-line diagnoses. This paper describes the on-line partial discharge measurement techniques in the generator stator windings. The experimental results from the UIAM #1 hydro-generator confirms a optimistic application of on-line generator diagnosis method as a reliable tool for evaluation of winding condition.

This paper describes the discharge characteristics of liquid nitrogen for plane-plane, needle-plane electrode at variation of gap spacing at atmospheric pressure. The important results obtained from this study are as follows. (1) Breakdown voltage of $LN_2$ for needle-plane electrode is higher than that of for plane-plane electrode and discharge duration tine is longer with increase of gap spacing at atmospheric pressure. (2) The formation of bubbles by evaporation is observed in spite of non-applying source at atmospheric pressure and the creation of corona confirmed for plane-plane electrode results from the bubbles. (3) The applied voltage-discharge magnitude( V-Q) characteristics of $LN_2$ showed hysteresis and the discharge magnitude decreasing and corona voltage increasing proportional to the pulse per second at atmospheric pressure.

The Monte-Carlo simulation was used to define the physical mechanisms of the initiation phase of pseudo-spark discharge. The pseudo-spark discharge employing the hollow cathode geometry is accompanied by very fast current rising and intense charged particle beams. In this model, time-dependent continuity equation for the electrons and ions were solved consistently with Poisson's equation for the electric field in a two-dimensional, sysmmetrically cylinderical geometry. From the simulation, a sequence of physical mechanisms that cause the rapid current rise associated with the onset of pseudo-spark discharge mode were identified.

The influence due to metallic particle contaminated on spacer surface is remarkable in the decreasing of dielectric strength in $SF_6$ GIS. In relation with this problem, We studied, AC flash-over voltage characteristics and breakdown mechanism are investigated under metallic particle initiated condition in $SF_6$ gas by varying the particle position, particle shape with a plane-plane electrode. The main results arc as follows 1. The small amount of the metallic particle in the gap do not make flash-over voltage to be influence, but the significant decrease of th flash-overed voltage is result in case of the big and long size of the metallic paraticle. 2. Influence of the flash-over voltage are lowest in the mid and are highest in the electrode of metallic particle position. 3. In case of the initiated metallie particle, The more the pressure are high, the more the recluced ratio of flash-over voltage are high. 4. The metallic particle shape which results in the reduced flash-over voltage forced the critical pressure to move in to the region of low pressure. 5. The existance of the metallic particle on the upper electrode side and high pressure make the decreasing ratio of flash-over voltage bigger than that of the ground side electrode.

This paper describes an experimental study of pattern recognition of partial discharge for three different discharge sources by using neural network(NN) system. The NN system is three layer feedforward connections and its learning method is a backpropagation algorithm incorporating an external teacher signal. Input information for NN is a statistical parameters of a discharge magnitude and the number of pulse count. After learning three typical input patterns, NN system offers good discrimination between different defects.

Ignitabilility of explosive gas mixture by spark of dry cell in case of short circuit by accident was studied for the purpose of evaluation of intrinsically safe characteristics of dry cell that manufactured in Korea. IEC type spark test apparatus, $21{\pm}2$ Vol% of hydrogen - air mixture, and dry cell that produced in Korea was used for the experiment. The result of this research could be used for design, manufacturing, and using the intrinsically safe electrical apparatus.

In recent years, fiberoptic technology is becoming indispensable in establishing communication networks due to its low loss, high capacity and non-inductive properties. In the power industry as well, the technology is being required to cable and facility monitering, and control system. But, duct in the manhole and space in the culvert are required to fiberoptic cable that is separated from power cable. Therefore, some cable makers and R&D has been studying the composite fiber/power cables. This report introduces the outline of ABF system, construction and properties of optical composite power cable that used ABF technology.

In order to investigate the effect of electrolyte solutions on the activities of bow-tie water trees in XLPE insulated power cable, we have tried to observe the characteristics on water treeing ( bow-tie type ) using several electrolyte solutions such as $CH_3COOH$, $MgCl_2$,HCl and NaCl solution and tap water. Bow-tie tree density in $CH_3COOH$ and $MgCl_2$ solution was higher than in any other solution, and the growth of tree was stimulated in NaCl and $CH_3COOH$ solution, and diffusion of bow-tie trees into insulation in $MgCl_2$, HCl and NaCl solutions was faster than in $CH_3COOH$ solution and water. Also, although the increase of applied voltage caused bow-tie tree density to be high, it didn't affect the growth of tree maximum length noticeably.

In this paper, we describes the research in condenser cone of $SF_6$ gas sealing end for 345KV oil-filled cable. The designed of condenser cone based on the results electric field analysis by electrostatics theory ana FEM. As a results. we have been designed the condenser cone and the inner insulation part of $SF_6$ seating end, the width and length, the number of condenser, the length of stress relief slope, the total length of condenser cone.

An air/quartz dielectric double barrier pulse discharge has been investigated to develop a novel si lent type ozone generator. It is found that there are very active pulsed coronas occurred in the airgap which are very useful for ozone generation. And, the corona onset voltage of the airgap of the air/quartz double barrier was enfluenced greatly by the airgap of the air/quartz dielectric double barrier, and depended greatly upon the airgap ranged of $0.0{\sim}3.0mm$ and by the quartz tube thickness ranged of $1.75{\sim}2.25mm$.

At present, the principle of puffer action in high current interruption is adopted in almost of the EHV(Extra High Voltage) and UHV(Ultra High Voltage) GCB(Gas Circuit Breakers). The thermal interruption capability of these GCBs critically depends on the pressure rise in the puffer cylinder at current zero. The pressure rise in the puffer cylinder depends on the puffer cylinder volume, flow passage and leakage area in the interrupter, stroke curve etc. Recently commercial CFD(Computational Fluid Dynamics ) packages have been widely adopted to calculate the pressure distribution in the interrupter. However, there are still several problems with it, e.g. very expensive price, moving boundary problem, computation time, difficulty in using the package etc. Thus, the calculation of the puffer cylinder pressure in simple and relatively correct method is essential in early stage of GCB design. In these paper, the model ing technique and computed results for EHV class GCB (HICO, 145kV 40kA and 362kV 40kA GCB) are presented and compared with available measured results.

In this paper, we describe that the acoustic PD detection is examined in the various structures and position shapes of sensors. We find that the acoustic waves rate the complexity in various structures and position shapes of sensors may reduce the complexity of the acoustic wave in the PD detection of transformers.

This paper describes a methodology for the three dimensional electric field calculation around parallel and orthogonal transmission lines. A nonuniform modeling method of finite line using linear line charges is proposed through the error analysis, Several examples of three dimensional electric field calculation are carried out by this method.

Laser-triggered-lightning is protection methed for power apparatus against lightning. It is necessary to understand the generation mechanism of laser produced plasma. So production of long distance laser-plasma-channel was numerically analyzed with electron growth equation and laser transport equation.

In order to substitute for the conventional measuring system which could bring about technical inconveiences, measuring techniques for the fast transient high voltage upto 100 kV and small signals less than 1 V are developed by use of Laser Source with Packets cell. for the former, capacitive voltage divider was specially designed for reducing the impulse voltage less than the half-wave voltage of pockets cell. For the tatter, interferometer type was employed as a mean to removing the fluctuation of Laser output intensity. And also the main beam through the Pockels cell and the reference beam from the Laser source are seperated before being detected respectively by photo diodes. And then, these two signals are amplified and compared for detecting only the small signals applied across the Pockels cell. Throughout this work, Laser-based measuring system is likely to enable us, at this moment, to detect correctly lightning impulse voltage upto 100 kV and the small signals less than 1 V upto the 2 MHz. Such a system could be employed as a possible diagnostic measuring system at the substation.

$SF_6$ gas has become an important insulation medium in modern electric power apparatus, because of its high insulation withstand levels and good arc quenching capability. For the application of $SF_6$ gas in GIS the estimation of insulation properties is a fundamental point. Moreover the reduction of withstand levels in case of inhomogeneous fields caused by particles or fixed protrusions is of special interest. It is known that the presence of free conducting particles in GIS can significantly lower the insulating level of $SF_6$ gas at elevated pressure and also it has been recently shown that dielectric strength is greatly reduced by fast transients such as disconnector surges where metallic particles are involved. In this paper, we have disigned the particle test chamber rated 362kV for the purpose of investigating the discharge characteristics in SF6 gas where inhomogenius fields are caused by metallic particles.

200-MW pulse modulators(total 11units) for the PLS linac employ the SCR phase control circuit. It controls 3-phase AC line voltage for the high-voltage DC power supply (DCPS, maximum of 25kVDC, 4.2A) which charges the pulse forming network(PFN). The PFN delivers 400kV, 500A, ESW $7.5{\mu}s$ pulse power to the 80-MW klystron amplifier tube. The SCR regulates 3-phase AC power and feeds to the high voltage transformer. Two different types of the transformer configurations namely ${\Delta}-{\Delta}$ and ${\Delta}-Y$, are alternatively installed to 11 modulator units for the suppression of harmonic noises. RC filters and reactors are also installed. Currently, approximately 110-kW of average AC power per unit is consumed at the normal operation level of the modulator with 30pps. This paper presents the operational characteristics of the high power pulse modulator, especially the experimental results of the AC line harmonic components generated by the operation of the high power pulse modulator to suppress the switching noises from the SCR and rectifying diode arrays.

In this study, when AC voltage is applied to block type treeing specimen which is fabricated with polyethylene which dielectric characteristics is excellent, from initial tree to final breakdown, Using acoustic emission method. we take statistically on parameter, which is skewness. We experimented on quenching condition and illustrated skewness locus plane so that studied interrelation of life expectation and parameter.

In this paper, we investigated the relationship between the needle electrode current and the needle electrode potential, The needle electrode potentials have influence on the needle electrode currents absolutely. So, to increase the needle electrode currents there is necessary to keep a high electric field if the charge reducer. for this, high insulation materials must be selected, and charge density of insulating oil must be high. In this experiment, the more a charge density of insulating oil increases, the more a needle electrode potential increases. So we could know what increasement of needle electrode potential increases a needle electrode current.

Some interesting corona characteristics of a airgap of penpoint-to-plate with a tracing insulator paper has been investigated in a temperature and humidity controlled metal chamber. It is found that the positive and the negative carriers in the plasma region could be understood from the waterdrop traces on the paper, which indicate the bombardment by the one of electron or positive gas particle from the plasma region of near the point. It is also found that a corona discharge could be used as a means of a humidifying, since the discharge makes dispersion of watersprays from the penpoint. And the negative corona was more effective for waterspray dispersion than the positive ones.

We developed the ion plating system, consisted of the Facing Target Magnetron Sputtering System and the r.f, electrode of the coil type, which was available to control the reactive and the adhesion between thin film and substrate, and studied about the discharge characteristics and the optimum condition in order to form the high quality thin film. The characteristics of discharge and plasma was measured as Double Probe and Electrostatic Retarding Grid Analyzer. The incident ion energy on the substrate was increased as the increasing r.f power, bias voltage. By the r.f electrode, the ionization rate of the sputtered particles was about 75%, and the mean incident ion energy depend on the value which was difference between the plasma potential and biased substrate potential.

Recently rotary-arc, thermal expansion and their composite interrupters are widely used in the distribution power system because they have lots of advantages in making the larger interrupting capacity, the smaller size, the lighter weight and the less surge. A model interrupter of rotary-arc type, which has constant stroke and thermal expansion volume, was studied by varying the design parameters, i.e. the number of turns of the driving coil, the inner diameter of the moving contact, the gas pressure and the shape of the fixed contact for this project. Short cicuit current interrupting tests were conducted to the model interrupters by varying the requirements from 42% to 175% of the test voltage, interrupting current and transient recovery voltage for the test duty No.4 of 7.2kV 12.5kA single phase test. The pressure rise, minimum and maximum arcing times were analyzed for each model interrupter. All types of model interrupters showed good interrupting performances and sufficient design margins for the ratings.

Recently, failure of COS(cut out switch) due to contamination has been increased. This paper is on the development of the contamination COS. 1 We designed a porcelain insulator of alternate shed for anti-contamination COS. 2 The COS was coated with HVIC(silicone) to improve resistivity to contamination. 3 The FOV characteristics of COS were examined to obtain dry FOV, wet FOV and contamination FOV.

Recently, Gas Circuit Breakers are rapidly replacing Vacuum Circuit Breakers in the medium voltage switchgear. This is due to the improved performance of - GCB in interrupting capability, price, weight, size etc., while the countermeasure to suppress the switching surges of VCB has not been satisfactory. Intensive research works on the GCB have been conducted in the world widely since 1980. Nowadays it is well known that the thermal expansion type GCB can provide- better performance than puffer type in the distribution power system. KERI has conducted researches in the GCB rated at 25.8kV 25kA with Jinkwang Co. using the thermal expantion principle since 1993. In this paper, the calculated results of electric and magnetic fields for the model GCB are presented and analyzed. The effect of permanent magnet used to improve the interruption capabilty at the low current level is also investigated. The design parameters for the interrupter inspected through the short-circuit tests conducted at high power laboratory of KERI.

A performance of the torch greatly depends on the plasma gas and the cooling gas. The plasma gas constricted by the nozzle concentrates electric power and momentum, so it can eject molten metal from a cut. As an electric arc constricted in a nozzle is more constricted through thermal pinch by the cooling gas, it is possible to transfer larger thermal concentration to the workpiece. The optimized parameter value in this study was given below. Plasma gas pressure is $4[kgf/cm^2]$ and gas mass flow is $30[{\ell}/min]$. Cooling gas pressure is $6[kgf/cm^2]$ and gas mass flow is $120[{\ell}/min]$.

In ECR and helicon reactors for plasma processing, a high density plasma is generated in a source region which is connected to a diffusion region where the processing takes place. Large density and potential gradients can develop at the orifice of the source which drive ion currents into the diffusion region. The average ion velocity may become the order of the sound velocity. Measurements of the ion saturation current to a Langmuir probe are used as a standard method of determining the plasma density in laboratory discharges. However, the analysis becomes difficult in a steaming plasma. We have used the HAMLET plasma simulator to simulate the ion flow to a large langmuir probe in an ECR plasma. The collection surface was aligned with the Held upstream, normal to the field, and downstream. ion trajectories through the electric and magnetic fields were calculated including ion-neutral collisions. We examines the ratio of ion current density to plasma density as a function of magnetic field and pressure.

Modulators Installed in PLS(Pohang Light Source) Linac are composed of a DC high voltage section, a charging section and a discharging section. PFN is charged by a resonant charging mechanism, and discharged by a switching device through the primary of the pulse transformer connected to a load. Charged PFN voltage must be well regulated to obtain stable output pulse voltage at the load. For this purpose, DCHV is controlled by a SCR controller with feedback signal, and PFN voltage is regulated by a De-Q'ing circuit. The full power operation test shows the pulse voltage regulation within ${\pm}0.13%$ with SCR feedback control alone, and within ${\pm}0.08%$ together with De-Q'ing. This paper describes the design concept and operational characteristics of the De-Q'ing circuit.

This paper studied the streaming electrification of the U.H.V. transformer with the spinning cylinder system, and compared and analyzed it with the conventional forced flowing system which uses a pump or gas for oil flowing. Also, accumulated surface voltage in its electrified material was measured with the electrostatic voltmeter, and the effect of insulation oil aging was measured. As results, in spinning cylinder system, characteristics of the streaming electrification to its rotational speed and oil temperature are same tendency as those of tile forced flowing system and it showed the spinning cylinder system is useful to study the streaming electrification. And, aging of insulation oil increases the electricity of streaming electrification at initial stage of aging.

Both Facing Target Sputtering(FTS) and Cylindrical Post-Magnetron Sputtering(CPMS) systems have been degigned in order to form high density plasma and to obtain high deposition rate. However, these two systems have some different applications, and discharge characteristics of these two systems are not well known. In this paper, the discharge characteristics and plasma parameters of both FTS and CPMS systems are studied experimentally. It is found that these two system show some different discharge characteristics under magnetic fields. The plasma density and electron temperature of these two systems are in the range of $10^{10}{\sim}10^{11}[cm^{-3}]$ and $3.5{\sim}5.5[eV]$, respectively.

Among the power system overvoltages, switching overvoltages are analysed in this paper, using EMTP(Electro-Magenetic Transient Program ) and TNA(Transient Network Analyzer ). From this analysis, the switching overvoltages are used to determine the BSL(Basic Switching Withstand Level) and the clearance of the transmission tower. Up to now the switching overvoltages were analysed by EMTP, but in order to determine the more exact value of BSL, not only digital but also analog method is required.

A potential to effective ozone generation for 4 kinds of gap, a hole-to-plate gap, a hole-to-hole gap, a hole-to-rod gap and a plate-to-plate gap in tap water has been investigated. It is found that the hole gaps indicated higher ozone generation compared to that of the plate-to-plate gap. As a result, the hole gaps could be an effective means to generate ozone in water by utilizing both of one generation mechanisms of the discharge and the electrolysis.

KEPCO is now promoting the new project of upgrading its highest system voltage from 345kV to 765kV. The main reason of this project is an insurance of bulk power transmission from power complexes at coast to power demand center at Kyoung-In area. The new system needs a careful approach to basic design to secure its reliability and to reduce the increase of investment cost. So, We introduced the basic philosophy of insulation design in spring meeting of this transaction. This paper, after preceding paper, deals with the insulation design example for 765kV transmission lines.

This paper presents the development technology of standard resistor divider for full lightning impulse voltage. The ability of high voltage bulk power equipment to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently International standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisions have been completed already worldwide, i.e. Europe, Japan, America etc.. In this viewpoint, we have also investigated the standard resistor divider with shield, which satisfies the IEC recommendation.

Salt deposited on the surface of insulators used in electric power system causes flash-over accidents. Therefore, the quantity of salt on insulators should be monitored not to exceed a critical value. We propose a new remote sensing technique to measure the quantity of salt on insulators of power systems. A pulsed laser beam is focussed on ah insulator to dissociate the salt to sodium atoms. The amount of the salt is measured from the intensity of the spontaneous mission from the sodium atoms. In this paper, a compact salt meter composed of pulsed Nd:YAG laser and omission signal detection system will be introduced. And measurement condition such as the sensitivity, detection range, required laser fluence will be investigated.

The severe conditions such as rated voltage of 800kV, gas pressure of $5kg/cm^2$ and rated lighting impulse withstand voltage of 2400kV were adopted for the design of spacers in the 800kV GIS to give a sufficient design margin. The design criteria on the maximum electric field strength of the center conductor and the insulator surface were established by considering the insulator surface characteristics, electrode area and surface effects in the unequal electric field strength of the given gap. The design parameters such as inter/outer envelope degree, thickness, inter/outer inserts, triple junction gap were determined by calculating the electric field using FLUX-2D program package and by referring to the published papers. The mechanical stress analysis was conducted on the feasible model spacers that showed good electric field distributions to confirm the sufficient mechanical design margin. The 800kV spacer designed as described above is now in the process of manufacturing.

It has been reported frequently that damage to underground electric power cable was brought about, due to attack by Insect such as termite (white-ant) and by rodent such as rat, in tropical and semitropical areas. Among these cable damages, we are likely to describe the damage to cable by termites as causing the severe trouble in cable operation and to solve this trouble with termite-proof method regarded as the most effective and economical one. This report covers our experiences of manufacturing the cable for anti-termite purpose and its intrinsic properties in cable operation.

In the system of underground transmission line, the rate of electrical failure is very low, but, if once occuring, the failure evolves into a paralysis of the system, the time of restoration is very long, the damage from stopping of power supply is very serious, and the cost of restoration is very great. Because of these problems, you must try to protect the system and equipment from every electrical failure by contributing much carefulness to the design and operation of the underground system. This study summerizes the results of simmulation tests about the effect of installing this protection device on the insulated joint box and the terminal end box.

This paper presents a new method for estimating partial discharge position using improved cross-correlation technique and neural networks in the power transformer. When ultrasonic signal is occurred by partial discharge, we detected these signals and calculated cross-correlation values with Hamming window. Also, we estimated partial discharge position using neural network with cross-correlation values. In the result of case study, we can estimate more accurately the partial discharge position than any other algorithms.

The Extra-high voltage XLPE cable is characterized by low transmission loss, large capacity, and high reliability. Conventionally, for XLPE cables of l54kV and above, aluminium sheath was used to be moisture barrier (thus preventing water tree deterioration of the insulation) and to protect cable core from physical stresses. However, as transmission capacity of the cable increases, so does the cable diameter and the corresponding aluminium sheath outer diameter and thickness. As a result, eddy-current loss in the sheath is increased, limiting the maximum current capacity of the cable itself. As an alternative to aluminium sheath, we have adopted stainless steel sheath with non-magnetic properties and a large resistivity, The new XLPE cable with stainless-steel sheath (CSZV cable) has drastically reduced eddy-current loss in the sheath.

To measure treeing, visual measurement with an optical microscope has been used to explain breakdown mechanism by treeing in materials. The conventional direct visual method of tree deterioration observation is difficult to measure in short time processing, and impossible to analyze the deteriorated area by treeing, direction of tree growth, tree patterns etc. In this paper, we have developed a tree-measuring system using image processing for the tree growth, the area of deterioration, and other progresses of treeing. As experimental result, image processing is an effective alternative to direct visual observation method.

This paper describes the measurement system of the magnetic field waveforms generated by lightning return strokes. The frequency bandwidth of magnetic field measurement system is from 270[Hz] to about 2.3 [MHz]. As the application experiment, the magnetic field generated by simple impulse and oscillating impulse currents, which are measured by a current transformer (Tek. AM503), is observed by the trial magnetic field measurement system. The obtained results are agreement with each other. A typical magnetic field waveform associated with lightning return strokes was recorded and presented.

In designing $SF_6$ puffer circuit breakers, analyzing are behavior during current zero region and thermal recovery characteristics after current interrupt ion is very important. In this paper, a mathematical are model based on the integral method has been based to analyze them. The pressure rise in the puffer chamber and the distributions of pressure, density, velocity and enthalpy inside nozzle are calculated and analyzed at current zero region. The influence of fault current magnitude and change of di/dt at current zero on the interruption capability of puffer circuit breakers is investigated. Finally, the calculated results are compared with the available results from experiment.