Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference (한국전기전자재료학회:학술대회논문집)
The Korean Institute of Electrical and Electronic Material Engineers
- Annual
1998.06a
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No Abstract, See Full-Text
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After Computer-based PD measurement was referred in the 1970's, the new technology and a number of digital system have been studied. And the selection of PD patterns, extraction of relevant information for PD recognition are discussed because the number of pulse as a function of discharge magnitude and discharge pulse as a function of the power frequency cycl4e offer the information of the aging insulation. This paper investigates the discharge phase(
$\phi$ ) and magnitude(q), as well as the number of discharge(n) with regard to discharge signals generated in power cable. Therefore, according to properties analysis on the distribution of$\phi$ , q and n, it is able to apply in the aging analysis of power cable which visual observation is impossible and distribution change of discharge signals offers much information for risk degree on aging progress of insulation materials. -
Water tree degradations have been considered as one of the most important causes of failure in underground distribution cables with polymeric insulation. Water tree growth is a preliminary step in the sequence of electrical tree initiation and electrical breakdown of the insulation. In this paper, needle electrode is made use of the etching methods and the pellet type specimen is made to observe the water tree in succession. In previous methods are able to observe the tree degradations without cutting and dyeing. The water tree image is recorded on VTR with CCD camera. The tree length of X, Y axis direction and aging area(treeing area) are calculated with image measurement. As a result of this study, water tree is observed by non-destructive method. Electrical tree is initiated from needle electrode tip only but water tree is initiated from total area of water electrode. Electrical tree owing to water treeing is initiated at low electric field and grown with discontinuously. Namely, water tree is shown up a different characteristics of tree growth.
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In this study, we investigated the electrical characteristics of silicone rubber that being used outdoor insulating material, which had been immersed in salt water. After immersed the sample in salt water, we measured surface hydrophobicity, weight loss and microscopic surface appearance, and then compared with these of the original. And we tested the electrical characteristics of the aged sample by the water under salt-fog. These electrical characteristics are described by the average of leakage current, peak pulse number, which are recorded by data acquisition system The experimental results show that the resistance against tracking and erosion is decreased significantly by water penetration.
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A plate-type ultrasonic linear motor using longitudinal and bending multi-vibration mode was designed and fabricated for card-forwarding device. The rotor consisted of piezoelectric ceramic plate and elastic materials. The performances of the motor were measured. As the experimental results, no-load speed of the motor was 0.6 m/s at 80 V in applied voltage. Starting torque was 1.4 mNm and maximum efficiency was 1.2 %.
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This paper is a study on a linear ultrasonic motor with a first longitudinal
$(L_1)$ and fourth bending$(B_4)$ double-mode rectangular plate. The stator vibrator is composed of an elastic material plate and of a piezo-ceramic element having a motion by electrical excitation. Each strain vector differs by$90^{\circ}$ generate travelling wave with the elliptical displacement motion of a point on the surface. To magnify displacement of longitudinal direction in elliptical displacement motion, the motor has a mechanism of the.displacement enlargement. In this paper, the vibration shape of the stator is simulated using the finite element method. A detailed model considered of the piezoelectric effect and of the exact geometry of the stator is used to calculate the displacement. The position of displacement mechanism is decided by the maximum displacement. -
In this paper, Pb(Z
$r_{0.53}$ $Ti_{0.47}$ )$O_3$ +x[wt%]C$r_2$ $O_3$ ceramics were fabricated, and thermal aging effects on the specimen were investigated. After thermal aging, the temperature coefficients of their resonant frequence became stable and only the specimen with C$r_2$ $O_3$ additives in them could have lower temperature coefficientient -
Dual mode resonators were fabricated using high temperature superconductor. The deposited material was
$Y_1Ba_2Cu_3O_{7-x}$ (YBCO) on MgO(100) substrate using pulsed laser deposition. Dual mode resonators were patterned by standard photolithography process and wet etching. At the back-side of the substrate, the ground plane with the metal layer of Ti and Ag was fabricated. The transition temperatures of YBCO films were 85-88 K, and network analyzer was used for testing the performance of the resonators. The input/output feedline angles of each resonator were$60^{\circ}$ and$100^{\circ}$ . The resonant frequency of resonators was 10 GHz. In this paper, dual mode resonator was fabricated for the application of satellite communication. -
We first report the GMR effect of new macroscopic ferrimagnet, Co-TbN. The Co-TbN system demonstrates typical macroscopic ferrimagnet properties which are a magnetic compensation Point and negative giant magnetoresistance (GMR) which is caused by the spin scattering contribution quite different from those of ordinary GMR materials. The Co-TbN system with 32 % TbN composition showed 0.72 % GMR in fields up to 8 kOe at room temperature and 9 % GMR at 250 K in 40 kOe. The GMR effect in the Co-TbN system increases with increasing temperature, which is due to the increase of ferromagnetic alignment of the Co and TbN in a field caused by the decrease of exchange coupling by temperature.
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Preparation of hexagonal strontium-ferrite by modified spray co-roasting(MSC:H) which is expected to shorkn the length of the process and to elevate the magnetic properties of hard ferrite was studied. We prapared
$Fe_2O_3/SrCO_3$ mixture powders by MSCR after stirring ionized$FeCI_2$ in distilled water with solid state$SrCO_3$ . And then calcined the mixture powders up to$1150^{\circ}C$ for Sr-ferrite powders It is possible to prepare hexaferrite powders with high saturation magnetization (Ms > 69 emu/g) , coercivity (Hc > 4000 Oe) The nlagnetic values of saturation magnetization iire higher than those achieved by the conventional technique. -
Recently, neural networks with self-adaptability like human brain have attracted much attention. It is desirable for the neuron-function to be implemented by exclusive hardware system on account of huge quantity in calculation. We have proposed a novel neuro-device composed of a MFSFET(ferroelectric gate FET) and oscillation circuit with CUJT(complimentary unijuction transistor) and PUT(programmable unijuction transistor). However, it is difficult to preserve ferroelectricity on Si due to existence of interfacial traps and/or interdiffusion of the constitutent elements, although there are a few reports on good MFS devices. In this paper, we have simulated CUJT and PUT devices instead of fabricating them and composed oscillation circuit. Finally, we have resented, as an approach to the MFSFET neuron circuit, adaptive learning function and characterized the elementary operation properties of the pulse oscillation circuit.
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Thermal treatment dependences of MFS devices in
$BaMgF_4$ on Si structures have been investigated.$BaMgF_4$ thin films have been directly deposited on the p-Si(100) wafers at a low temperature of$300^{\circ}$ in an ultra high vacuum(UHV) system. After in-situ post-deposition annealing was conducted for 20 s at$650^{\circ}$ , bias and temperature were applied to$BaMgF_4/Si$ structures. Although X-ray diffraction analysis showed that the films were polycrystalline in nature before and after bias temperature, the C-V properties were some different between with and without bias-temperature treatment. -
Prototype MFSFET′s using ferroelectric oxide LiNbO
$_3$ as a gate insulator have been successfully fabricated with the help of 2 sheets of metal masks and demonstrated nonvolatile memory operations of the MFSFET′s. The estimated field-effect electron mobility and transconductance on a linear region of the fabricated FET were 600$\textrm{cm}^2$ /V.s and 0.16 mS/mm, respectively. The drain current of the "on" state was more than 4 orders of magnitude larger than the "off" state current at the same "read" gate voltage of 0.5 V, which means the memory operation of the MFSFET. A write voltage as low as$\pm$ 3 V, which is applicable to low power integrate circuits, was used for polarization reversal. -
In this work, the freestanding GaN single crystalline substrates without cracks were grown by hydride vapor phase epitaxy (HVPE). The GaN substrates, having a current maximum size of 350
$\mu\textrm{m}$ -thickness and 10${\times}$ 10$\textrm{mm}^2$ area, were obtained by HVPE growth GaN on sapphire substrate and subsequent mechanical removal of the sapphire substrate. A lattice constant of c$\_$ 0/=5.18486${\AA}$ and a FWHM of DCXRD was 650 arcsec for the single crystalline freestanding GaN substrate. The low temperature PL spectrum consist of excitonic emission and deep donor to acceptor pair recombination at 1.8 eV. The Raman E$_2$ (high) mode frequency was 567 cm$\^$ -1/ which was the same as that of strain free bulk single crystals. The Hall mobility and carrier concentration was 283$\textrm{cm}^2$ /V$.$ sec and 1.1${\times}$ 10$\^$ 18/ cm$\^$ -3/, respectively. The freestanding and crack-free GaN single crystalline substrate suitable for the homoepitaxial growth of GaN, and the HVPE method are promising approaches for the preparation of large area, crack-free GaN substrates. -
In this Paper, we investigate the electrical properties of ultra-thin(70
${\AA}$ ) nitrided(NO) and reoxidized nitrided oxide(ONO) film that ale considered to be premising candidates for replacing conventional silicon dioxide film in ULSI level integration. we studied I$\sub$ g/-V$\sub$ g/ characteristics to know the effect of nitridation and reoxidation on the current conduction, leakage current time-dependent dielectric breakdown(TDDB) to evaluate charge-to-breakdown(Q$\sub$ bd/), and the effect of stress temperature(25, 50, 75, 100$^{\circ}C$ ) and compared to those with thermal gate oxide(SiO$_2$ ) of identical thickness. From the measurement results, we find that reoxidized nitrided oxide(ONO) film shows superior dielectric characteristics, leakage current, and breakdown-to-charge(Qbd) performance over the NO film, while maintaining a similar electric field dependence compared to NO layer. Besides, ONO film has strong resistance against variation in temperature. -
The SONOSFET Shows low operation voltage, high cell density, anti good endurance due to modified Fowler-Nordheim tunneling as memory charge injection method. In this paper, therefore, the NOR-type Flash EEPROM composed of SONOSFET, which has fast lead operation speed and Random Access characteristics, is proposed. An 8
${\times}$ 8 bit NOR-type SONOSFET Flash EEPROM had been designed and its electrical characteristics were verified. Read/Write/Erase operations of it were verified with the spice parameters of SONOSFETs which had Oxide-Nitride-Oxide thickness of 65${\AA}$ -165${\AA}$ -35${\AA}$ and that of scaled down as 33${\AA}$ -53${\AA}$ -22${\AA}$ , respectively. When the memory window of the scaled-down SONOSFET with 8V operation was similar to that of the SONOSFET with 13V operation, the Read operation delay times of the scaled-down SONOSFET were 25.4ns at erase state and 32.6ns at program state, respectively, and those of the SONOSFET were 23.5ns at erase state and 28.2ns at program state, respectively. -
Film characteristics of thin ONO dielectric layers for MONOS(metal-oxide-nitride-oxide-semiconductor) EEPRM was investigated by AES and AFM. Second derivative spectra of AES Si LVV overlapping peak provided useful information for chemical state analysis of superthin film. The ONO films with dimension of tunneling oxide 24
${\AA}$ , nitride 33${\AA}$ , and blocking oxide 40${\AA}$ were fabricated. During deposition of the LPCVD nitride films on tunneling oxide, this thin oxide was nitrized. When the blocking oxide were deposited on the nitride film, the oxygen not only oxidized the nitride surface, but diffused through the nitride. The results of ONO film analysis exhibits that it is made up of SiO$_2$ (blocking oxide)/O-rich SiON(interface/N-rich SiON(nitride)/-rich SiON(interface)/N-rich SiON(nitride)/O-rich SiON(tunneling oxide). -
Ferroelectric PZT(40/67)/PZT(60/40)heterolayered thin films were Prepared by the alkoxide-based Sol-Gel method. PZT(40/60) and PZT(60/40) stock solutions were made and spin-coated on the P7Ti/Si02/Si substrate alternately. These PZT(40/60) and PZT(60/40) films were dried at 300
$^{\circ}C$ for 30min to remove organic materials and were sintered at 650$^{\circ}C$ for 1 hour to crystalize into a perovskite structure. The coating and heating procedure were repeated 6 times to form heterolayered films. Increasing the number of coating, coercive field was decreased. The relative dielectric constant, loss, remanent polarization and coercive field of the 4-coated PZT heterolayered were 1200, 4.1[%], 30.794[${\mu}$ C/㎡] and 147.22[kV/cm], respectively. -
In this paper, We analyzed the current-voltage characteristics with n-type silicon substrates concentration and temperature variations (Room temperature, 50
$^{\circ}C$ , 75$^{\circ}C$ ) in platinum silicide and silicon junction. The electrical parameters of measurement are turn-on voltage, saturation current, ideality factor, barrier height, dynamic resistance in forward bias and reverse breakdown voltage according to variations of junction concentration of substrates and measurement temperature variations. As a result, the forward turn-on voltage, reverse breakdown voltage, barrier height and dynamic resistance were decreased but saturation currents and ideality factor were increased by substrates increased concentration variations in platinum silicide and n-silicon junction. In increased measurement temperature (RT, 50$^{\circ}C$ , 75$^{\circ}C$ ), the extracted electrical parameter values of characteristics were rises by increased temperature variations according to the forward and reverse bias. -
An optical modulator with CPW electrode on Ti:LiNbO
$_3$ optical waveguide was fabricated and chterized. The electrical-optical bandwidth measurement showed an optical response of -3dB at 10 GHz and S11 less than -l0dB unto 20GHz. The typical specifications are . 5.6V of driving voltage, 4.2dB of Insertion loss and 30dB of on/off extinction. -
A optical phase modulator of 5Gbps was fabricated on LiNbO
$_3$ by Ti diffusion for optical communications. In this Paper the pigtailing, mode patterns and insertion loss were discussed. And the device Properties of driving voltage and bandwidth were measured. -
We report some methods for measuring a LiNbO
$_3$ optical phase modulator bandwidth. Since Mach-Zehnder waveguide type, one of methods for modulation bandwidth measurement, is comparatively simple and useful, it was adapted in this work. In order to confirm this method, the waveguide of single and Mach-Zehnder type were fabricated on the same wafer. The Mach-Zehnder interferometric waveguide and the single channel waveguide were used for the measurement of the phase modulator's driving voltage and bandwidth for device fabrications, respectively. Ti-860$\AA$ in-diffusion was achieved in a wet-bubbling oxygen environment at 105$0^{\circ}C$ /8hours. LINbO$_3$ internal chips were pigtailed to PMF(polarization maintaining fiber)/SMF(single mode fiber) using an epoxy curing technique. Examined were optical properties such as an insertion loss, propagation loss and mode size, and the loss mechanism of optical coupling between an optical fiber and a waveguide was considered. -
In the present study, the luminescence characteristics and the effect of conductivity on cathodoluminescene of CaTiO
$_3$ :Pr was studied using dick specimens sintered at various temperatures and atmosphere. As a sintering temperature was increased from 1100 to 1400$^{\circ}C$ , conductivity of CaTiO$_3$ :Pr phosphor was improved and CL brightness was also increased about four times and decay times was reduced from 0.29 to 0.21 msec. And all samples prepared in Ar showed high conductivity, CL brightness and short decay time in comparison with those sintered in air. -
In this paper, we studied on electro-optical (EO) characteristics of photo-aligned twisted nematic (TN)-LCD. We obtained that uniform LC alignment in TN-LCD with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (PI) surface increases according to increasing irradiation time for 10 to 60 min. The voltage-transmittance and response time characteristics of photo-aligned TN-LCD with UV light irradiation time of 60 min were almost same in comparison with conventional TN-LCD were observed. From the results, we suggest that photo-aligned TN-LCD with LPUV light irradiation on PI surface is useful in applying LCD as for rubbing-free treatment method.
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In this paper, we studied the electro-optical(EO) performance of photo-aligned twisted nematic(TN)-liquid crystal display(LCD) with oblique non-polarized ultraviolet(UV) light irradiation on polyimide(Pl) surface. We observed that the voltage-transmittance and response time characteristics of photo-aligned TN-LCD is almost same compared to conventional TN-LCD. Also, we observed that the voltage-holding-ratio(VHR) of photo-aligned TN-LCD is almost same compared to conventional TN-LCD.
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In this study,
$Al_2O_3/MgO$ bilayer was prepared with Electron-beam evaporation and the properties of the film was investigated in order to improve the property of MgO film, which is used for the protection layer in PDP(P1asma Display Panel). The thickness of$Al_2O_3/MgO$ bilayer was optimized by the Matrix Theory for the fabrication of antireflection structure for 5350A wavelength. The secondary electron emission yields of as-deposited film and annealed film were measured and compared, the bilayer was considered for the applicability as PDP. XRD showed the strong (200) primary peak of MgO. The intensity of (200) peak in the film annealed at 300C was decreased. As the result of SEM analysis for MgO films and Alz03 films, it is considered that the morphology of the films were improved of roughness and it were condensed by annealing. -
Generally the structure of powder electroluminescent devices (PELDs) on ITO-film was makeup of the ZnS:Cu phosphor layer and BaTiO
$_3$ insulating layer. The active layer, which consists of a suitably doped ZnS powder mixed in a dielectric, is sandwiched between two electrodes; one of which are ITO film and the other is aluminum. In this paper, three kinds of powder eleotroluminescent devices (PELDs) : WK-A(ITO/BaTiO$_3$ /ZnS:Cu/Silver paste). WK-B(ITO/BaTiO$_3$ +ZnS:Cu/Silver paste) and WK-C(ITO/BaTiO$_3$ /ZnS:Cu/BaTiO$_3$ /Silver paste), fabricated by spin coating method, were investigated. To evaluate the luminescence properties of three kinds of PELDs, EL emission spectroscopy, transferred charge density and time response of EL emission intensity under square wave voltage driving were measured. -
The electro-optical properties of PDLCs ( Polymer Dispersed Liquid Crystals ) that have been interested for applications to projection display devices lately are significantly improved. For this improvement, we optimized not only the material parameters of liquid crystal and polymer but also the process conditions. Using TL series liquid crystals and polymer PN393 provided from Merck, we obtained the optimized process conditions such as cell gap, LC concentration, curing temperature and curing time. Under these conditions, we have achieved PDLC cells of threshold voltage 2.6V. contrast ratio 260 and negligible hysteresis.
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This work was carried out to develop a pattern on the nanometer scale using plasma polymerization and plasma etching. This study is also aimed at developing a resist for the nano process and a vacuum lithography process. The thin films of plasma polymerization were fabricated by the plasma po1ymerization of inter-electrode capacitively coupled gas flow system. After delineating the pattern at accelerating voltage of 30[kV]. ranging the dose of 1∼500[
${\mu}$ C/$\textrm{cm}^2$ ], the pattern was developed with dry tree and formed by plasma etching. By analysing of the molecule structure using FT-lR, it was confirmed that the thin films of PPMST contains the functional radicals of the MST monomer. The thin films of PPMST had a highly crosslinked structure resulting in a higher molecule weight than the conventional resist. -
This paper presents the results of measured permittivity of PCB sheet material in the frequency range of 0.1[GHz] - 2[GHz] and temperature range of
$25[^{\circ}C]$ -$85[^{\circ}C]$ . Microstrip lines with different physical length are implemented to measure the attenuation and phase shift of the signals though these lines. The loss factor of these materials could be obtained with the dielectric constant and the attenuation of the microstrip lines. -
PLZT thin films were fabricated with different Zr/Ti ratios by pulsed laser deposition. PLZT films deposited on Pt/Ti/SiO
$_2$ /Si substrate. This PLZT thin films of 5000${\AA}$ . thickness were crystallized at 600$^{\circ}C$ , 200 mTorr O$_2$ press. 2/55/45 PLZT thin film showed a maximum dielectric constant value of$\varepsilon$ $\_$ r/=1500, and dielectric loss was 0.O$_3$ . At 2/70/30 PLZT thin film, Coercive field and remnant polarization was respectively 19[kV/cm], 8[${\mu}$ C/$\textrm{cm}^2$ ]. -
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$LiCoO_2$ powder was synthesized at>$700^{\circ}C$ ,>$850^{\circ}C$ by solution route. In this paper, we investigated X-ray diffraction, and charge-discharge performance for$LiCoO_2$ /Li and$LiCoO_2$ /MPCF cell. The$LiCoO_2$ /Li ceSl exhibited a high avmge discharge potential of 38-3% and a good cycle life performance at 5(hnA/g during chargedischarge cycling between 43-3.0V. And, the$LiCoO_2$ MPCF cell showed a high average discharge voltage of 3.6-3.W and a excellent cycle life prfomam during chargedischarge cycling b&wm 4 2-2.W. As a result, the$LiCoO_2$ powdm syd-eizd by solution route is a good cathode material for lithium ion secondary battery. -
Since P-ELD(powders type electroluminescent device) phenomena were found by G.Destriau at first In 1936, lots of studying was performed in order to realize surface emission devices and flat panel display as a backlight. Due to the problem of low luminance and color and so on, it was delayed. Recently using electric field and thermal effect which can change it\`s molecular arrangement, it can be developed using photoelectric properties of P-ELD. P-ELD in this study was prepared by casting method. Basic structure is ITO/Phosphor/insulator/Al sheet, each layer was mixed by binder, which concentration 11p(poise) for phosphor, 8p(poise) fort insulator. Dielectric properties was investigated first and emission properties of P-ELD based on ZnS:Mn,Cu/ZnS:Cu,Br mixture. P-ELD prepared in this work exhibits about 100cd/㎡ 1-kHz simusoidal excitation.
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The layered trivanadate, LiV
$_3$ O$_{8}$ has been investigated as a cathode material for secondary lithium batteries. Early in its development the preparation method of LiV$_3$ O$_{8}$ strongly influenced its electrochemical properties, such as discharge capacity, rate capability and cycling efficiency. In the present experiment, a new synthesis route has been applied to obtain LiV$_3$ O$_{8}$ . Instead of the conventional high temperature technique leading to the crystalline form, a solution technique producing the amorphous form has been used. This material, after dehydration, shows an electrochemical performance exeeding that of the crystalline one. The rationale for this behavior mainly lies in microscopic factors, i.e., in the possibility for the unit cell of amorphous LiV$_3$ O$_{8}$ to insert up to 9 Li$^{+}$ , instead of six for crystalline LiV$_3$ O$_{8}$ . The ultrasonically treated products in water were characterized by XRD, TGA, DSC, and SEM. These measurements showed that the ultrasonic treatment process of crystalline LiV$_3$ O$_{8}$ causes a decrease in crystallinity and considerable increases in specific surface area and interlayer spacing.g. -
MLS capacitor with lipid ultra thin films were deposited by Langmuir-Blodgett (LB) method on the sillicon wafer. The current versus voltage and capacitance versus voltage relationships are depend on the applied voltage, electrode area and electrode materials. LB films deposited were made of L-
$\alpha$ -DLPC, the 1 layer's thickness of 35$\AA$ was measured by ellipsometer. And MLS capacitor with different electrode materials, the work function of these materials was investigated to increase the leakage current. The result indicated the lower leakage current and very high saturation value of capacitance was reached within 700-800 pF when the two electrode was Ag. And$\varepsilon$ $_1$ ,$\varepsilon$ $_2$ versus photon energy showed good film formation. -
The new type polymer electrolyte composed of polyacrylonitrile(PAN) baed polymer electrolyte contain LiClO
$_4$ -EC/PC and LiPF$\sub$ 6/-EC/PC were developed for the weightless and long or life time of lithium polymer battery system with using polyaniline electrode. The gel type electrolytes were prepared by PAN at different lithium salts in the glove box. We prepared for polymer electrolyte with knife casting method. The minimum thickness of PAN gel electrolyte for the slim type is about <400∼500$\mu\textrm{m}$ . These gel electrolytes showed good compatibility with lithium electrode. The test cell of Li/polymer electrolyte/Lithium cobalt oxide solid state cell which was prepared by different lithium salt was researched by electrochemical technique. Resistance of polymer electrolyte which consist of LiClO$_4$ is more less than that of LiPF$\sub$ 6/ and cycle life is more longer than that of LiPF$\sub$ 6/. -
In this paper, breakdown strength and dielectric characteristics were experimented in the structures of insulation/insulation/insulation and insulation/semiconductor/insulation by using of insulation material of polyethylene terephthalate film. The breakdown strength and the permitivity of each specimen were measured as a function of temperature and frequency respectively. The breakdown strength of PET/PET/PET did not changed greatly but that of PET/SEMl/PEr increased as a function of temperature. As the frequency inclosed, the permitivity of PET/PET/PET and PET/SEMI/PET decreased. The tan
$\delta$ of PET/PET/PET showed lower than that of PET/SEMl/PET in low frequency but higher in high frequency . -
We have investigates a surface pressure, a displacement current and a charge measurement by distance of between electrode 1 and water surface of organic monolayers. And the displacement current was generated during compression of Arachidic acid mono1ayers at a air-water interface. The result from our work show that the displacement current of a Langmuir(L) film for Arachidic acid monolayers has the different maximum points according to the electrode distance. We are known that the displacement current and a charge was generated in inverse proportion to electrode distance d.
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We experimentally investigated the dielectric relaxation phenomena of a liquid crystal monolayers by the Displacement current techique and displacement current flowing across monolayers is analyzed using rod-like molecular model. It is revealed that the dielectric reaxation time
$\tau$ of monolaters in the isotropic polar orientational phase is determined using a linear relashionship between the monolayers compression speed$\alpha$ and the molecular area. The dielectric relaxation time of phospholipid monolayers was examined on the basis of the analysis developed here. -
In this paper, we used the
$BaTiO_3$ system ceramics with high temperature stability for high voltage devision, and rosen type-piezoelectric transformer for high voltage measurement. when Line-high voltage is 13,20O[V], Input voltage of piezoelectric transformer type-actuator is about 390CV1, and output voltage of it is 26.5FVI on the no-load. And also, temperature stability from>$-25^{\circ}C$ to>$50^{\circ}C$ is less than${\pm}4.45%$ -
In this paper, The load characteristics on the voltage gain and efficiency were analyzed sing an lumped constant equivalent circuit of the piezoelectric transformer. These analytical results are confirmed by experiments. Theoretical values of voltage gain were nearly constant with experimental ones. However, It was shown that theoretical values of efficiency had higher values than experimental ones.
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This Paper present a new structure for a piezoelectric transformer, operating in thickness extensional vibration mode. Modified PbTiO
$_3$ family ceramics were used for the Piezoelectric transformer, because it is a material with large anisotropy between electromechanical coupling facters k$\sub$ t/ and k$\sub$ p/. Piezoelectric transformer was fabricated that is 20mm long, 20mm wide and 3.1mm thick. Resonant frequencies of sencond thickness extensional vibration mode is 1.72MHz at loading resistance 100{$\Omega$ ]. And Voltage gain of piezoelectric ceramics is showed 0.53 at resonant frequency of sencond thickness extensional vibration mode. -
In this paper, we study on the surface breakdown of Epoxy composite in silicon oil. Breakdown field strengths were simulated by using FEM with the experience data of surface breakdown of Epoxy composite. The surface endurance and field distribution (kV/mm) of Epoxy composite were calculated by FEM.
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In examining application of polymer as electrical insulators, it is very important to perform accelerated aging test substituted the process which polymer insulator is degraded for long-time by the process of short-time. The purpose of this paper is to examine the properties of water degradation which affect on the efficiency of epoxy insulator. To do this, the surface properties on epoxy insulating material have been investigated after long-time accelerated degradation in boiling water condition. The experimental results showed the contact angle and surface resistivity after treatment to decrease the sample of water treatment. In dielectric properties, dielectric constant was increased by the aging development with water treatments.
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In this paper, specimens stirred with the several kinds of benzotriazole(following as BTA) addition which is very effective to decrease the streaming electrification, are tested to investigate the change of properties for insulating fluid using in ultra-high voltage transformer, and it will give a guideline to find out a proper quantity of BTA addition for the most effective suppression against the streaming electrification. In GC, we could not find out the change of the physical properties in an insulating fluid by BTA. In a flowing transformer oil, the characteristics on dielectric of specimen contained BTA 10[ppm] are superior to the others.
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Surface electrical conduction in insulator is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the widely used materials for outdoor insulator - porcelain, EPDM, Silicone rubber - were discussed by measuring properties of average leakage current and scintillation discharge pulses under artificial contamination conditions. The artificial contaminations used were deionized distilled water fog, 0.5wt% NaCl salt fog of light pollution and 2wt% NaCl salt fog of medium pollution. The average leakage current was appeared linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage was most different to that in case of dry and clean condition. In case of salt fog pollution condition. The leakage current was increased above critical voltage. The scintillation discharges were also activated at the level the leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.
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The composite of polyvinylalcohol(PVA) and lithium salts(LiBF
$_4$ ) is prepared for a solid-state electrolyte of electric double layer capacitor. The composite shows a good ionic conductivity. The solid-state electric double layer capacitor is made of PVA-LiBF$_4$ composite, activated carbon and etc.. As evaluation of characteristics of capacitor, capacitance change which measured by charge-discharge test with 2.2V~0V at 8$0^{\circ}C$ for 800 hours, was about 10%. The gravimetric and volumetric capacitance were 10.0 F/g~30.0 F/g and 16.0F/㎤~F/㎤, respectively. -
XLPE/VLDPE (Crosslinked polyethylene/very low density polyethylene) blends were prepared by a twin screw extruder and their electrical properties such as water tree and breakdown characteristic were measured. it was found that both water tree and breakdown characteristics of XLPE were improved by the addition of VLDPE to polyethylene. It was also found that the extent of improvement of electrical properties by the addition of VLDPE to polyethylene depends on the type and concentration of VLDPE.
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In this study, The water tree characteristics were investigated when crosslinking coagent was added in XLPE/EnBA blends. When XLPE was blended with EnBA, there was a decrease of water tree length as an increase of nBA contents in XLPE/EnBA20 blends. The effect of crosslinking coagent. A was better than those of other crosslinking coagents B, C and D in water tree retardation. In case of XLPE/EnBA/Crosslinking coagent blends, water tree length was increased as the crosslinking coagents were increased from 0.2 to 2 phr in 2.0 phr DCP content. To clarify the effects of crosslinking coagent, the DCP contents were changed from 1.5 to 2.0 par in the same crosslinking coagent contents. Then, there was a decrease of water tree length as an increase of crosslinking coagent contents in 1.5 and 1.8 phr DCP contents.
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In this paper, we have investigated how morphology and electrical properties in Polyphenylene sulfide(PPS) are changed by uniaxial elongation. XRD pattern shows that interplanar distance and crystallinities are decreased by increasing elongation ratio. Electrical conduction mechanism of PPS is explained as schottky emission from analysis of electrical current. The electrical current is decreased by increasing elongation ratio. The conductivity is changed remarkably above the glass transition temperature around
$(82^{\circ}C)$ . The band gap of PPS is evaluated as 3.9-4(eV) from the results of photoconductivity. Increarnent of elongation ratio gives us some information about deep trap formation from photocurrent. -
The effects of post curing conditions on thermal properties of alumina filled epoxy resin system DGEBA/MDA/SN were investigated. As the post curing time increased at 15
$0^{\circ}C$ , the glass transition temperature increased from 121 to 124, slightly. As the heating rate increased, high thermal decomposing temperature (T$_{d}$ ) and most decomposing temperature (T$_{p}$ ) increased. For the case of post-cured system at 15$0^{\circ}C$ for 4 days showed lower values than virgin system. At the post curing condition the system must have been thermally degraded.ded. -
In this experiment, A1
$_2$ O$_3$ thick films were prepared by electrophoretic method using A1$_2$ O$_3$ fine powder of which compositions were FA-5-500 and FA-5-900. As a result of measurement for A1$_2$ O$_3$ thick film characteristics due to applied voltage, deposition time and additives condition, the result of deposited films exhibited superior than others when the applied voltage and deposition time were 65 volts and 2 seconds in case of using modified suspension medium added additives. When taken a heat treatment and sintered A1$_2$ O$_3$ deposition film made by electrophoresis with A1$_2$ O$_3$ suspension medium at 1$700^{\circ}C$ for 5 minutes in hydrogen environment, it could be fabricated in good uniformity and electric characteristics as the A1$_2$ O$_3$ insulating thick films. -
Ferroelectric
$LiNbO_3$ thin films were grown directly on Si(100) substrates by 13.55MHz RF magnetron sputtering system using a ceramic target ($Nb_2O_5/Li_2C0_3$ = 51.4/48.6). Because high temperature process have to avoided to prevent degradation of the interface (insulator/Si),$LiNbO_3$ thin films were deposited below$300^{\circ}C$ . After as-deposited films were performed RTA treatments in an oxygen ambient at$600^{\circ}C$ for 60s, electrical measurements performed films before and after anneal treatment. In high field region, the leakage current density of the films after annealing was deceased about 4order and the resistivity of these was increased to about5\times 10^{11} \Omega \cdot cm$ at 500kV/cm. In accumulation region of C-V curve, we calculated dielectric constant of thin film$LiNbO_3$ as 27.9 which is close to that of bulk value. -
Ca
$F_2$ films have superior gate insulator properties than conventional gate insulator such as$SiO_2$ , Si$N_{x}$ ,$SiO_{x}$ , and T$a_2$ $O_{5}$ to the side of lattice mismatch between Si substrate and interface trap charge density($D_{it}$ ). Therefore, this material is enable to apply Thin Film Transistor(TFT) gate insulator. Most of gate oxide film have exhibited problems on high trap charge density, interface state in corporation with O-H bond created by mobile hydrogen and oxygen atom. This paper performed Ca$F_2$ property evaluation as MIM, MIS device fabrication. Ca$F_2$ films were deposited at the various substrate temperature using a thermal evaporation. Ca$F_2$ films was grown as polycrystalline film and showed grain size variation as a function of substrate temperature and RTA post-annealing treatment. C-V, I-V results exhibit almost low$D_{it}$ (1.8$\times$ 10$^{11}$ $cm^{-1}$ /le$V^{-1}$ ) and higher$E_{br}$ (>0.87MV/cm) than reported that formerly. Structural analysis indicate that low$D_{it}$ and high$E_{br}$ were caused by low lattice mismatch(6%) and crystal growth direction. Ca$F_2$ as a gate insulator of TFT are presented in this paper paperaper -
This paper presents a 6-bit self-calibrated D/A converter designed with current cell matrix structure. This structure is based on the current-cell matrix configuration using a regulated gate cascode current cell with 3-way switch. using from CMOS process and 5V power supply, the simulated conversion rate is 45.78MHz and the average mismatching properties among current sources are reduced to 0.02% and 0.005%, respectively when 1% and 0.5% errors of current sources are considered.
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This work presents the analysis of
$1\times2$ polymer waveguide thermo-optic switch using asymmetric Y-splitter at the wavelength of 1300nm. Because of the high thermo-optic coefficient of polymeric materials the design of efficient switches were feasible. For the numerical simulation of these switches the finite difference beam propagation method has been employed. Design rules for a$1\times2$ polymeric switch have been defined by using the numerical techniques. -
Organic-based electroluminescent devices have attracted lots of interests because of their possible application as large-area flat pan디 display. In this study, current-voltage (I-V) characteristics of MEH-PPV thin films was investigated using various metal as a top electrode, where MEH-PPV thin films were prepared on 170 substrate by spin coating method and various metal such as Al, Ag, In, MgIn was deposited on MEH-PPV thin films as a top electrode.
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The liquid crystal (LC) alignment and pretilt angle generation using photo-alignment method were investigated in this study. We obtained that the monodomain alignment of nematic(N) LC increases with increasing irradiation time in a cell with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (Pl) surfaces. We consider that the monodomain alignment is able to be anisotropic dispersion force due to photo-depolymerization of polymer with LPUV light irradiation on Pl surface. Also, we observed that the uniform alignment of NLC is obtained in a cell with normally LPUV light irradiated on Pl surface at 30 min. and then oblique LPUV is secondly irradiated on Pl surfaces rotated by 90
$^{\circ}$ . The pretilt angle of NLC is generated about 1.5$^{\circ}$ with oblique angle 60$^{\circ}$ . -
In this study, the effect of the crystallinity of polyimide (Pl) and the birefringence of the nematic liquid crystal (NLC) for pretilt angle generation on rubbed PI surface containing thiophenylene moieties has been demonstrated. The induced optical retardation produced in rubbed Pl surfaces decreases on increasing the imidization temperature. We suggest that the pretilt angle of 4-cyano-4'-n-pentybiphenyl (5CB) depends on the crystallinity of the rubbed Pl. The order of pretilt angle in NLCs is 5CB>PCH5
$\geq$ CCH5 at rubbing strength(RS)=150mm (medium rubbing) on rubbed PI surfaces. We suggest that on rubbed Pl surfaces the pretilt angle increases with increasing number of phenylrings in the NLC core. -
In this study, we investigated the generation of pretilt angle for nematic liquid crystal (NLC) in a cell with oblique non-polarized ultraviolet (UV) light irradiation on polyimide (PI) surfaces. It was found that the monodomain alignment of the NLC is obtained in a cell with an angle of incidence of 70∼85
$^{\circ}$ on PI surface. We consider that the monodomain alignment of NLC is attributed to anisotropic dispersion force effect due to Photo-depolymerization of polymer on PI surfaces. Also, pretilt angle of NLC is generated about 3$^{\circ}$ with an angle of incidence of 70∼75$^{\circ}$ . It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecules and the polymer surfaces. -
In this paper, the monodomain alignment of nematic liquid crystal(NLC) in the cell fabricated by one side transcription alignment method on PI surface with side chain were investigated. The LC alignment produced by the transcription alignment method is attributable to a memory effect of the NLC on Pl surfaces. We observed that the pretilt angle of NLC is generated about 3.6
$^{\circ}$ in a cell with one side transcription alignment on PI surface. Also, the electro-optical(EO) performance of TN-LCD with one side transcription alignment method on PI surface will be discussed. -
In recent years, miniaturization has become the key factor in the development of mobile communication system. Portable communications and computing devices suffer from two conflicting requirements which are device size to be as small as possible and large, high resolution display. These problems can be solved by virtual display. Any display in which the user views an image through an optical system is a virtual display. It provides a display which is high resolution, appears large to the viewer and at the same time occupies little physical space. In this study, handhold units of mobile communication was investigated through use of the SLA(Scanned Linear Array). The basic SLA mechanism comprises a linear array of LED's, a magnifying lens, and a scan mirror. To optimize virtual image, we investigated optical system design and operating condition for each part.
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The electron swarm parameters in the
$CF_4$ (O.l%, 5%)+Ar mixtures are measured by time of flight method over the E/N(Td) range from 10 to 300LTdl. A two-term approximation of the Boltzmann equation analysis and Monte Carlo simulation have been also used to study electron transport coefficients. We have calculated W, NDL, NDT,$\alpha$ and the limiting breakdown electric field to gas mixtures ratio in pure$CF_4$ gas and$CF_4+Ar$ mixtures. The measured results and the calculated results have been compared each other paper. -
Ultrasonic signal characteristics related with the growth of electrical trees in epoxy resin are examined under 67[Hz] ac voltage application along with a CCD camera and PD current method. The ultrasonic sensor with a resonant frequency of 200[Hz] supported by a mechanical spring is attached directly to the lower-side of plane electrode. The magnitude of Partial discharge and count rate of ultrasonic signals have been measured according to the tree growth from a needle tip in an epoxy sample.
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A Study on the Diamond thin firms Synthesized by Microwave Plasma Enhanced Chemical Vapor DepositionThe methastable state diamond films have been deposited on Si substrates using MWPCVD. Effects of each experimental parameters of MWPCVD including CH
$_4$ concentrations, Oxygen additions, Operating pressure, deposition time, etc. on the growth rate and crystallinity were investigated. The best crystallinity of the finn at 3% methane concentration addition of oxygen to the CH$_4$ -$H_2O$ mixture gave an improved film crystallinity at 50% oxygen concentration. Upon increasing the operating pressure and time, the growth rate and crystallinity were increased simultaneously. -
Surface electrical conduction in insulator is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the widely used materials for outdoor insulator - porcelain, EPDM, Silicone rubber - were discussed by measuring properties of average leakage current and scintillation discharge pulses under artificial contamination conditions. The artificial contaminations used were deionized distilled water fog, 0.5wt% NaCl salt fog of light pollution and 2wt% NaCl salt fog of medium pollution. The average leakage current was appeared linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage was most different to that in case of dry and clean condition. In case of salt fog pollution condition, The leakage current was increased above critical voltage. The scintillation discharges were also activated at the level. the leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.
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In this paper, we obtained the data, which is required in training the neural network and diagnosing the degradation degree, by introducing the AE detection that is effective method in ordinary degradation diagnosis on activation. Automatic detection system to detect acoustic. As the results of generalization tests by appling neural network to the unknown AE patterns obtained from specimens, firstly as to evaluate an objective performance of neural network, the recognition ratio for no-void specimen is appeared. Also, in the evaluation for the adaptability of neural network with a untrained type of no-void specimen, it is confirmed that the result appears.
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The Power measurement that can measure a single quantity does not smooth to install a system, and are not convenient to use. These measuring values are vary difficult for mutual operation and analyzing, and that have too many problems to compile measured databases. If each single measured values are mutual assist, correction and reform, the system will be able to be improved by minimizing differences between measure quantities and as making many different measurement system (Voltage, Current, Power and Resistor) is installed in one system. This study is useful to develope the power measurement system that is easier to analyze and management by database all of the parameter values because the power measurement system is able to be interbased with PC as requirement of industralization and information age.
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Finite element analysis was investigated on the stress distribution at the 2-D model of piezoelectric ceramic actuators. The y direction maximum stress decreased with a(internal electrode gap) size until 0.4 mm and is not much difference with c(external electrode thickness) size. The stress distribution with internal layers is almost same, and the stress distribution of load condition is higher than that of no load condition. The y direction maximum stress increased exponentially with the number of layer and saturated at 260 layers. In the case of defective actuator, the stress distribution is smaller than that of normal actuator.
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Conjugated oligomers have been already used as active layers in field effect transistors, photodiodes and electroluminescent devices. Particularly thiophene oligomers such
$\alpha$ -sexithiophene($\alpha$ -6T) attract great interest for its prospective app1ications in large-area flexible displays. In this study, we investigated the contact properties between the organic semiconductor$\alpha$ -6T and metals such as Au(Gold), Ag(Silver), Cr(Chromium), Al(Aluminum), Cr(Chromium). Using the Transmission Line Model(TLM) method, specific contact resistances of the metal lines in contact with the$\alpha$ -6T were determined. From the current-voltage characteristics, electrical conductivity of the$\alpha$ -6T films is found. -
Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)
$_3$ (Phen)/Al(A), glass substrate/ITO/TPD/Eu(TTA)$_3$ (phen)/Al(B) aNd glass substrate/ITO/TPD/Eu(TTA)$_3$ (Phen)/A1Q$_3$ /Al (C) structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$ (phen) as an emitting material, and tris(8-hydroxyquinoline) Aluminum (AlQ$_3$ ) as an electron transporting layer. Etectroluminescent(EL) and I-V characteristics of Eu(TTA)$_3$ (phen) with a various thickness were investigated. This structure shows the red EL spectrum, which is almost the same as the PL spectrum of Eu(TTA)$_3$ (phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a dc operation voltage of 9V. Electrical transporting phenomena of these structures was explained using the trapped-charge-limited current model with I-V characteristics. -
Pixel-Design Array Simulation Tool(PDAST) was used to profoundly the gate signal distortion and pixel changing capability, which are the most critical limiting factors for high-quality TFT-LCDs. Since PDAST can simulate the gate, data and pixel voltages of a certain pixel on TFT array at any time and at any location on an array, the effect of the resistivity of gate line material on the pixel operations can be effectively analyzed. The gate signal delay, pixel charging ratio, level-shift of the pixel voltage were simulated with varying the resis5tivity of the gate line material. The information obtained from this study could be utilized to design the larger area and finer image quality panel.
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In this paper, the (Sr
$_{1-x}$ Ca$_{x}$ )TiO$_3$ (SCT) thin films were deposited at various substrate temperature using RF magnetron sputtering method on optimized Pt-coated electrodes (Pt/TiN/SiO$_2$ /Si). An influence of substrate temperature and annealing temperature on the structural and dielectric properties are investigated. The substrate temperature changed from 100[$^{\circ}C$ ] to 500[$^{\circ}C$ ] and crystalline SCT thin films were deposited abode 400[$^{\circ}C$ ]. All thin films had (111) preferred orientation, the (100) oriented films were obtained at the substrate temperature above 400[$^{\circ}C$ ]. The dielectric constant changes almost linearly in the temperature region of -80~+90[$^{\circ}C$ ], the temperature characteristics of the dielectric loss exhibited a stable value within 0.1, then not affected by substitutional contents. The capacitance characteristics appears a stable value within$\pm$ 5[%]. -
The solid solutions of the Pb(Sc
$\_$ 0.5/Nb$\_$ 0.5/)$\_$ 0.57/Ti$\_$ 0.43/O$_3$ system were prepared. In the PSNT system, it had been known that two-phase region between the rhombohedral and tetragonal phases was observed between 0.425 of PT at room temperature. In this paper, Fe$_2$ O$_3$ -doped 0.57PSN-0.43PT composition was prepared by conventional method. The dielectric and strain properties were examined using an computerized measuring apparatus, and the resonance characteristics were measured using an impedance gain phase analyzer. We got the data of dielectric constant, dielectric loss, piezoelectric coefficient, piezoelectric voltage coefficient, frequency constant strain constant mechanical quality factor and electromechanical coupling factor. -
The effect of glass flit addition on microwave dielectric properties of BaTiO
$_3$ -3TiO$_2$ ceramic was studied. Addition of glass frit to this system obtained sintered sample below sintering temperature 105$0^{\circ}C$ . At BaTiO$_3$ -3TiO$_2$ + g1ass frit 3wt% + BaWO$_4$ 6 wt%m, this ceramic showed excellent microwave properties of dielectric constant 34, Q$\times$ f 8,100, temperature coefficient of resonant frequency 4 ppm/$^{\circ}C$ . -
A high performance, high-dielectric stripline filter has been developed. The filter consists of planar resonators and its structure is made of high permittivity multilayer ceramic. The performance is distinctive with its attenuation pole. An equivalent lumped circuit is derived to explain the behavior of the attenuation pole quantitatively. A precise design procedure is also described.
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Degradation characteristics of the Pr-based ZnO varistor with
$Y_2O_3$ content (0.0-4.0 mol!%j were investigated. It was appeared that the variation of the J-E characteristics in the reverse direction before and after the applied stress with increasing$Y_2O_3$ content was larger than that of the forward direction but the variation was extrernly small. For all varistor, the leakage current with the stress time during the applied stress somewhat increased initialy but afterthat was almost constant or slightly decreased. The overall varistor voltage and nonlinear coefficient were less than 5%. Especially, in the case of Pr-based ZnO varistor containing 2.0 mol% to 4.0 mol%$Y_2O_3$ , the variation of breakdown voltage and nonlinear coefficient was less than 1% and 5%. respectively. As a result, they showed good stability. -
We studied relation of X-ray diffraction and charge/discharge capacity of LiMn
$_2$ O$_4$ cathode. LiMn$_2$ O$_4$ is prepared by reacting stoichiometric mixture of LiOH.$H_2O$ and MnO$_2$ (mole ratio 1 : 2) and heating at$700^{\circ}C$ , 80$0^{\circ}C$ for 24hr, 36hr, 48hr, 60hr and 72hr. Through X-ray diffraction pattern, it is analyzed that crystal structure and lattice parameter and peak ratio so on. We obtained X-ray diffraction pattern that varied lattice parameter and peak intensity by function of calcining temperature and time. Cathode active materials calcined at 80$0^{\circ}C$ for 36hr shown that (111)/(311) Peak ratio at X-ray diffraction pattern was 0.37. It means that crystal structure is formed very well in this temperature and time. In the result of charge/discharge test, cathode active material calcined at 80$0^{\circ}C$ for 36hr displayed excellent charge/discharge properties than that of cathode active materials calcined at other temperature and title. In this study, we certified that spinel structure basied cubic is formed very well at 80$0^{\circ}C$ for 36hr. In this case, (111)/(311) peak ratio at X-ray diffraction is 0.37, and charge/discharge properties is excellent than others. -
The formation of the
$YBa_2Cu_30_{7_\delta}$ (Y123) thick films has been investigated by a surface diffusion Imcess between$3BaCu0_2$ +2CuO composite coating powder and a$Y_2BaCuO_5$ (Y211). This reaction has been studied in the temperature of$930^{\circ}C$ and$940^{\circ}C$ for 2h to 10h in an oxygen atmosphere. The Y211 substrates becomes covered by co-precipitation of Y123 grains and CuO inclusions. X-ray diflractotnctn. revealed that the lager consisted of an orthorhombic crystal structure. The maximum Jc of$400A/\textrm{cm}^2$ is abtained when the specimen was heat-treated at$930^{\circ}C$ for 6h on the Y211 substrate. -
BSCCO-2223 superconducting tape made by PIT method can be influenced in the critical characteristics by the heat treatment and the mechanical processing. Particulary, it has been reported that the mechanical deformation affects the core density, texture of the core, sausaging and so on. Therefore the accurate control of the deformation process is very important to achieve high J
$\sub$ c/. In this study, we measured the J$\sub$ c/ variation for different rolling reduction rate and investigated the change of core shape to compare the formation of sausaging. -
Electrical breakdown characteristics of liquid nitrogen(LNd used as both coolant and insulator for high
$T_c$ superconductor system is very important. This paper presents dynamic breakdown characteristics of liquid nitrogen by quench penomena of thermal bubble under high electric field. As the result, the breakdown mechanism of$LN_2$ depends on thermal bubble effect. The breakdown voltage decreases slightly with increasing heating. In the Electrode arrangement, electrical breakdown voltage of horizontal arrangement appears lower than that of vertical arrangement. -
Shuttered Co-Cr thin films have been developed continuously as one of the major candidates for high density recording media. In this study, Co-26at%Cr thin films with c-axis oriented h.c.p. structure prepared by a improved facing targets sputtering system. We find that the effect of microstructural changes of sputtered Co-Cr thin films on magnetic properties and changes of crystal orientation due to variation substrate temperature.
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In this paper, based on the research of high temperature YBCO superconductor, using the Yb instead of Y, with the YbBCO superconductor powder which was combined by means of conventional solid reaction, textured directional crystal was prepared by MCP method and the character was analyzed. Mixing the starting elements and calcining at 890
$^{\circ}C$ , 900$^{\circ}C$ , 910$^{\circ}C$ , single phase YbBCO, Yb$_2$ BaCuO$\sub$ 5/ and BaCuO$\sub$ 2/ were certified. And from the powder which was calcined at 900$^{\circ}C$ the, sample which became texture-growth by MCP method was well oriented. The result of DTA measurement, the fusing point of YbBCO superconductor and it\`s critical current was measured to be 979$^{\circ}C$ , 87K respectively. The critical current density was obtained at the value of 700A/$\textrm{cm}^2$ (77K. 0H) calculated by Bean's Model using the measured hysteresis curve of VSM. -
The SmBa
$_2$ Cu$_3$ O$\sub$ x/ single crystals were used as seeds to induced YBCO growth in MTG process. As the result, the large bulk oriented YBCO superconductors were prepared with dimension of plane 21mm and 32mm in diameter and 10mm in height. The typical Jc value of the sample is 6.5${\times}$ 10$^4$ A/$\textrm{cm}^2$ and its flux float force is 4.6N/$\textrm{cm}^2$ . The oxygen absorption in large bulk textured YBCO samples in pure oxygen was studied at several constant temperatures. It can be divided into two steps: a chemical reaction step and a diffusion step. -
The magneto-optical properties of Co/Co
$_2$ TiSn two-phase magnet films were studied. These films show that relatively large Kerr rotations which are -0.4 deg. at the wavelength of 400 nm, compared to that of pure Co. It is conceivable that the magneto-optical effects may be due to both contributions of ferromagnetic Co matrix and ferromagnetic Co$_2$ TiSn Heusler alloy precipitate. The perpendicular magnetization curve domonstrates a typical bubble domain hysteresis loop. the saturation magnetization change of the annealed film is less sensitive to temperature in the low temperature region and the Curie temperature of Co$_2$ TiSn Heusler alloy precipitate is a little higher in the annealed film. These can be explained by the increase of the number of Co-Co exchange interaction in Heusler alloy structure resulting from the change of chemical ordering by annealing. -
(Ba, Sr)TiO
$_3$ [BST] thin films were fabricated on Pt/SiO$_2$ /Si substrate by RF sputtering technique. The Mic개structure, dielectric and electrical properties of BST thin films were investigated with sputtering pressure. Dielectric constant and dielectric loss of the deposited thin film at sputtering pressure of 5 mTorr were about 91 and 1.9(%), respectively. Increasing sputtering pressure, leakage current was increased. It was found that leakage current of BST thin films was depended on the sputtering pressure. -
After etching Al-Cu alloy films using SiC1
$_4$ /Cl$_2$ /He/CHF$_3$ plasma, a corrosion phenomenon on the metal surface has been studied with XPS (X-ray photoelectron spectroscopy) and SEM (Scanning electron microscopy). In Al-Cu alloy system, the corrosion occurs rapidly on the etched surface by residual chlorine atoms. To prevent the corrosion, CHF$_3$ plasma treatment subsequent to the etched has been carried out. A passivation layer is formed by fluorine-related compounds on the etched Al-Cu surface after CHF$_3$ and SF$_{6}$ treatment, and the layer supresses effectively the corrosion on the surface as the CHF$_3$ and SF$_{6}$ treatment pressure increases. The corrosion could be suppressed successfully with CHF$_3$ and SF6 treatment in the pressure of 300mTorr.orr. -
New Ag-deposited graphite anodes were developed using wet chemical reduction methods for depositing Ag metal onto graphite particles. In this paper, we investigated X-ray diffraction pattern and charge-discharge behavior for Ag-deposited graphite anode. The Lithium ion cello using Ag-deposited graphite anode showed a high average discharge voltage of 3.6∼3.W and a excellent cycle ability than that of conventional graphite. Little capacity loss in this battery may be due to the highly durable Ag-deposited graphite anodes.
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Electroluminescence is the light emission obtained by an electrical excitation energy passing through a phosphor under an applied high electrical field. EL are paid much attention on flat panel display as a backlight and indicator, which are divided into ACPRL(alternating-current powder electroluminescent) and ACTFEL(alternating-current powder electroluminescent). In this paper, Electric and emission properties on ACPEL are investigated based on ZnS:Cu phosphor. The basic structure on this is ITO glass/phosphor/insulator/ backelectrode, CR-M which has high efficiency on thermal properties and dielectric Properties was introduced and BaTiO
$_3$ as a insulating layer in order to increase app1ied electric field on phosphor. Changing on Dielectric and emission Properties was caused by a different viscosity of binder which filled on space between phosphor particle. 60cd/$m^2$ under 60V, 2kHz sinusoidal was gotten from ACPELD prepared in this work. -
Lithium insertion has been studied in a number of vanadium oxides with special regard to their application as the active materials in rechargeable lithium cells. Very high stoichiometric energy densities for lithium insertion are found for several of these materials. Some vanadium oxides, e.g. V
$_2$ $O_{5}$ and V$_{6}$ $O_{13}$ , are now being used in commercially developed rechargeable Li batteries. Another material which is receiving remarkable attention for this kind of cells is LiV$_3$ $O_{8}$ . In variety of ternary lithium-vanadium oxides, the lithium content can be varied between certain limits without major changes in the vanadium oxygen lattice. In our worts, the oxides which do net form these thermodynamically stable bronzes can still accommodate large amounts of lithium at ambient temperature, forming kinetically stable insertion compounds. These compounds owe their existence to the whereas lithium is easily introduced into these open structures. The oxides investigated are rather poor electronic conductors; the conductivity decrease with increase in the lithium content. Improvements in the electrode fabrication technique are needed to alleviate this Problem.oblem. -
Electroluminescent(EL) devices based on organic thin films have attracted lots of interests in large-area light-emitting display. One of the problems of such device is a lifetime, where a degradation of the cell is possibly due to an organic layers thickness, morphology and interface with electrode. In this study, light-omitting organic electroluminescent devices were fabricated using Alq
$_3$ (8-hydroxyquinolinate aluminum) and TPD(N,N'-diphenyl-N,N'-bis(3-methylphenyl(1-1\`-biphenyl]-4,4'-diamine). Where Alq$_3$ is an electron-transport and emissive layer, TPD is a hole-transport layer. The cell structure is ITO/TPD/Alq$_3$ /Al and the cell is fabricated by vacuum evaporation method. In a measurement of current-voltage characteristics, we obtained a turn-on voltage at about 9 V. We also investigated stability of the devices using buffer layer with blend of PEI (Poly ether imide) and TPD by varying mot ratios between ITO and Alq$_3$ . In current-voltage characteristics measurement, we obtained the turn-on voltage at about 6 V and observed an anomalous behavior at 3∼4 V. And we used other buffer layer of PEDT(3,4-pyrazino-3',4'-ethylenedithio-2,2',5,5'-tetrathiafulvalenium) with ITO/PEDT/TPD/Alq$_3$ Al structure. We observed a surface morphology by AFM(Atomic Force Microscopy), UV/visible absorption spectrum, and PL(Photoluminescence) spectrum. We obtained the UV/visible absorption peak at 358nm in TPD and at 359nm in Alq$_3$ , and the PL peaks at 410nm in TPD and at 510nm in Alq$_3$ . We also studied EL spectrum in the cell structure of ITO/(TPD+PEI)/Alq$_3$ /Al. -
Electroluminescence(EL) come from the light emission obtained by electrical excitation energy passing through a phosphor layer under applied high electrical field. The preparation and characterizations of light emitting ACPEL(alternating-current powder electroluminescent) cell based on two kinds of phosphor mixed ZnS:Mn, Cu and ZnS:Cu phosphor. Basic structure is ITO/Mixed Phosphor/insulator/Al sheet, each layer was mixed by binder, which concentration 11p for phosphor, 8p for insulator. Dielectric properties was investigated first and emission properties of P-LED based on ZnS:Mn,Cu/ZnS:Cu,Br mixture. Emission spectra exhibits two kinds of main peaks at 100V, 1kHz sinusoidal excitation.
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During the past decade, substantial research effort has been directed into the development of rechargeable lithium batteries. Although some improvements in cycle life and efficiency have been achieved, the reversibility of the lithium electrode remains as a significant problem in aprotic solvent based electrolyte. The major problems limiting cycle life are short circuits resulting from growth of lithium dendrites, and macroscopic shape changes during the recharge process. As an anode material of lithium rechargeable battery, amorphous carbon materials have been studied extensively because of their high electrochemical performance. The polyacene materials prepared from phenol refine at relatively low temperature(550∼750
$^{\circ}C$ ) show a highly Li-doped state up C$_2$ Li state without liberation of Li cluster. So it has largely layered distance 4${\AA}$ . The Li storage mechanism as well as the large hysterisis observed in the voltage-capacity profile of the amorphous carbone materials are still the subjects of controversy. We prepared each polyacene material various temperature and investigated electrochemical property. The mole ratio of [H]/[C] is 0.027∼0.015 range. -
In this paper, the silicon-nitride membrane structure for IR sensor was fabricated through the etching and the direct bonding. The PT layer as a IR detection layer was deposited on the membrane and its characteristics were measured. The attack of PT layer during the etching of silicon wafer as well as the thermal isolation of the IR detection layer can be solved through the method of bonding/etching of silicon wafer. Because the PT layer of c-axial orientation rained thermal polarization without polling, the more integration capability can be achieved. The surface roughness of the membrane was measured by AFM, the micro voids and the non-contacted area were inspected by IR detector, and the bonding interface was observed by SEM. The polarization characteristics and the dielectric characteristics of the PT layer were measured, too.
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The maleate copolyrner(
$C_{18}MA-VE_2$ ) is used as sensitive materials and deposited on the slide-glass substrates at room temperature using Langmuir-Blodgett(LB) method. The results of current-time(1-t) measurements are performed to investigate the gas-detection characteristics of the sensitive LB films in the presence of organic gases just as chloroform, acetone, ethanol, methanol using the apparatus for the gas-detection measurement. Several interesting responses are observed at room temperature, such as reversible response, sensitivity and response time. Response time and sensitivities are evaluated 160~220[sec], minimum 6[times], maximum 70[times] for each organic gas by adsorption and penetration of the organic gases in the relation concentration of 100[%], respectively. -
There are lots of researches which are using quratz crystal in order to apply it to sensors, for example, mass detect sensor, humidity sensor, gas sensor, etc. We tried to apply quartz crystal to the sensor using the resonant frequency and the resistance properties. Four kinds of fatty acid which are having the same head group are coated at the surface of quartz crystal, the shift of the resonant frequency and the resistance are observed according to length of the tail group. Myristic acid
$(C_{14})$ , palmitic acid$(C_16)$ , stearic acid$(C_{18})$ , and arachidic acid$(C_{20})$ were coated by Langmuir-Blodgett(LB) technique. As results, the resonant frequency shift was observed linearly. However, there are some difference compared with Sauerbrey's equation. It can be explained by the effect of the temperature property and/or humidity. On the other hand, the shift of the resistance was observed nonlinearly. -
Piezoresistive pressure sensors have fabricated using electrochemical etch-stop technique. Si diaphragm having thickness of n-epi. layer was fabricated and used to detect pressure range from 0 to 1 kg/
$\textrm{cm}^2$ . Piezoresistors were diffused 3${\times}$ 10$\^$ 18/ cm$\^$ -3/ and placed at diaphragm edge for maximum pressure detection. The characteristics of electrochemical etch-stop in TMAH/lPA/pyrazine solution were also discussed. I-V curves of n and p-type Si in TMAH/lPA/pyrazine solution were obtained. Etching rate is highest at optimum etching condition, TMAH 25wt.%/IPA 17vo1.%/pyrazine 0.1/100m1, thus the elapsed time of etch-stop was reduced. -
Electro Discharge Machining (EDM) is a so-call non-conventional machining technique. This paper presents the experimental results of an EDM technique for the fabrication of microholes on #7440 pyrex glass substrates. With various applied voltages and at various concentration of NaOH solution, the glass substrates have been microdrilled using the copper electrodes of which diameters are 250
$\mu\textrm{m}$ to 450$\mu\textrm{m}$ . The machined throughholes have been observed the top diameter, the bottom diameter and machining time have been measured. The experimental results show that the machining time decreases as the concentration of NaOH solution increases, the applied voltage increases and the needle diameter decreases. Also, the top diameter increases as the needle diameter increases or the applied voltage increases. The bottom diameter decreases as the needle diameter decreases or the applied voltage decreases. -
Platinum-Cobalt alloy thin films were deposited on Al
$_2$ O$_3$ substrate by r.f. cosputtering for RTD temperature sensors. We made Pt-Co alloy resistance patterns on the Al$_2$ O$_3$ substrate by lift-off method and investigated the physical and electrical characteristics of these films under various conditions (the input power, working vacuum, annealing temperature, thickness of thin films) and also after annealing these films. At input power of Pt : 4.4 W/$\textrm{cm}^2$ , Co : 6.91 W/$\textrm{cm}^2$ , working vacuum on and annealing conditions of 1000$^{\circ}C$ and 60 min, the resistivity and the sheet resistive thin films were 15${\mu}$ $\Omega$ $.$ cm and 0.5$\Omega$ /$\square$ , respectively. The TCR value of Pt-Co a films was measured with various thickness of thin films and annealing temperature. T TCR value is gained under condition 3000${\AA}$ of thin films thickness and 1000$^{\circ}C$ of temperature. These results indicate that Pt-Co alloy thin films have potentiality for the wide temperature ranges. -
In this paper, Electret is formed to range voltage -5[kV] to -8[kV] by corona charging in PTFE film and sensor is manufactured by method of moments in sensing infra sonic. Charges of charged film are calculated also TSC measurement and induced potential of sensing electrode according to the charges is become aware of computer simulation. Electret Infra Sonic Transducer, which is designed and manufactured according to the potential and electric field simulation in using method of moments, is proved as it is effectively. Because sensitivity that measured under 10[Hz] is that average value of sensitivity rising rate is 6.34 [dB/oct] as average value is
$\pm$ 1 [dB/oct] range -5[kV] to -8[kV] in corona charging film. As a result, it is believed that characteristic of acquired transducer can be application of medical treatment, industry, and animal life researches and the study of noise elimination, what's more, is required. -
In this paper, organic thin film LED(light emitting diode) having ITO glass/Alq
$_3$ /Al structure using an Alq$_3$ was fabricated by the vacuum evaporation and the absorbance, wave length, I-V characteristics were investigated, Electroluminescence of green and wavelength of 510[nm] were observed in this device. We observed absorbance form 320[nm] to 430[nm] and knew unstability of Alq$_3$ material as light emitting device. -
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Present paper is devoted to the brief analysis of the present state and the prospects for the future of technology of the high frequency devices and high speed integrated circuits based on the
$A_{3}B_{5}$ semiconductor compounds, including the$A_{3}B_{5}$ -heterostructures, in the republics of the former USSR. tunneling quantum well-structures were widely used. -
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The peculiarities of the polyvinylpyrrolydone (PVP) interaction with transition metal ions of the first row in solution were studied. It was shown that PVP macromolecules due to their swelling conformation in organic solvents form the stable metal complexes. Metal ions were bond with oxygen and nitrogen atoms of PVP lactam rings. In water solution every metal ion interacts with one or two oxygen atoms out of 10-12 monomer units of the polymer. The additional contraction of PVP macromolecule coils in water have been found out by dissolving of the polymer metal complexes (PMC) synthesized in organic media. Toxicity, blood forming and immune stimulating activity and pharmaco-kinetic too of obtained polymers and their metal completes have been investigated. The factors and effects that responsible fur changing of PMC physical-chemical and biological properties have been estimated.
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The scientiic and technological aspects of water-soluble and water-swelling polymers to be synthesized from the domestic raw materials of Kazakhstan are described. The application area of polymeric reagents in medicine, biotechnology, agriculture, enhanced oil recovery, ecology is also considered.
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Kudaibergenov, S.E.;Nurkeeva, Z.S.;Mun, G.A.;Sigitov, V.B.;Nam, I.K.;Kan, V.A.;Khutoryanskii, V.V. 473
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Sol-gel processing, which started some decades back as a laboratory curiosity, has proved to be a powerful and versatile technique for the synthesis of materials. The utility of the sol-gel method for producing glass and ceramic materials in the form of powders, fibers, thin films and bulk shapes with high purity, functional microstructures and potentially high chemical homogeneity at relatively low temperature (compared to conventional processing) has been discussed.
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The problem of production of new materials based on polyheteroarylenes and other polymers combining good mechanical and dielectric properties. radiation and chemical stability with heat- and thermal stability is related with the development of efficient synthesis technique of starting low-molecular compounds. Alicyclic dianhydrides are believed to be the promising monomers to synthesize various polymers.
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The SmBa
$_2$ Cu$_3$ O$\sub$ x/ single crystals were used as seeds to induced YBCO growth in MTG process. As the result, the large bulk oriented YBCO superconductors were prepared with dimension of plane 21mm and 32mm in diameter and 10mm in height. The typical Jc value of the sample is 6.5${\times}$ 10$^4$ A/$\textrm{cm}^2$ and its flux float force is 4.6N/$\textrm{cm}^2$ . The oxygen absorption in large bulk textured YBCO samples in pure oxygen was studied at several constant temperatures. It can be divided into two steps: a chemical reaction step and a diffusion step. -
The measurement of the amplitude and phase of electric fields on high voltage transmission lines is important for several reasons including a) Metering and determination of power flow, b) protective relaying. and c) fault sensing. The work reported here is directed toward a major improvement to optically based, electric-field sensors. This is a signal processing based technique for overcoming the instabilities of conventional, optically-based, electric-field sensors to changes in optical power or temperature.
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To understand the effect of surface roughness on silicon wafer bonding, a continuum mechanical model is presented. This model is based on Obreimoff's experiment and the contact theory of rough surfaces. The surface energy of silicon was calculated to be much reduced than the theoretical value. Problems are discussed concerning surface film effects and the assumption of constant asperity radius and statistical distribution function.
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We demonstrate stable return-to-zere direct pulse modulation of a gain-switched DFB semiconductor laser at a data rate of 2.5 Gbit/s. The effects of change in drive conditions on eye diagrams of the outputs are explored and an optimum operating regime is determined.
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In surface grinding, the conditions of the grinding wheel has much more significant effect on the machined workpiece as compared to other metal removal processes. The contact between the grinding wheel and the workpiece introduce heat and resistance, which restrict the self-dressing of the grits and result in burrs cracks on the workpiece. Therefore, before or during the grinding operation, it is necessary to self-dressing the grinding wheel for more accurate performance. In general, however, the choice of the dressing time has made by the operator's own decision or the condition of the workpiece. In this paper, a new method for finding the optimal dressing time of the grinding wheel is proposed. In order to develop a more sophisticated methodology, a non-contacting in-process optical measurement method using a laser beam has been introduced to find the glazing, loading, and spilling of the grinding wheel Simultaneously, a three-dimensional computer simulation of the grinding operation has been attempted based on the contact mechanism between the grinding wheel and the workpiece. The grains of the grinding wheel are simulated and the optimal dressing time is determined based on the amount of grain wear and work surface roughness.
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Kwak, Seung-Uk;Kim, Jeong-Il;Jeong, Keun-Won;Park, Kyong-Bae;Kang, Kyong-In;Kim, Hyen-Uk;Lee, Kwang-Bae 515
In this paper, we propose a new fault tolerant architecture for high availability systems, where for module internal operations both processor modules perform the same tasks at the same time independently of each other while for module external operations both processor modules act actively. That is, operations of synchronization between dual processor modules except clock synchronization are requested only when module external operations are executed. The architecture can not only improve system availability by reducing system reintegration time but also reduce performance degradation problem due to frequent synchronization between dual processor modules. The clock unit consists of a clock generator and a clock synchronization circuit. This supplies a stable clock signal under clock unit disorder of any processor module or rapid clock signal variation. And this architecture achieves system availability and data credibility by designing as symmetrical form. -
Kim, Jeong-Il;Kwak, Seung-Uk;Jeong, Keun-Won;Song, In-Keun;Yoo, Choong-Yeol;Lee, Kwang-Bae;Kim, Hyen-Ug 521
In this paper, we propose a fast algorithm for fractal image coding to shorten long time to take on fractal image encoding. For its performance evaluation, the algorithm compares with other traditional fractal coding methods. In the traditional fractal image coding methods, an original image is contracted by a factor in order to make an image to be matched. Then, the whole area of the contracted image is searched in order to find contractive transformation point of the original image corresponding to the contacted image. It needs a lot of searching time on encoding and remains limitation in the improvement of compression ratio. However, the proposed algorithm not only considerably reduces encoding tin e by using scaling method and limited search area method but also improves compression ratio by using bit-plane. When comparing the proposed algorithm with Jacquin's method, the proposed algorithm provides much shorter encoding time and better compression ratio with a little degradation of the decoded image quality than Jacquin's method. -
An optimized PWM switching strategy for an induction motor voltage control is developed and demonstrated. Space vector modulation in voltage source inverter offers improved DC-bus utilization and reduced commutation losses, and has been therefor recognizedas the perfered PWM method, especially in the case of digital implementation. Three-phase invertor voltage control by space vector modulation consists of switching between the two active and one zero voltage vector by using the proposed optimal PWM algorithm. The prefered switching sequence is defined as a function of the modulation index and period of a carrier wave. The sequence is selected by suing the inverter switching losses and the current ripple as the criteria. For low and medium power application, the experimental results indicate that good dynamic response and reduced harmonic distortion can be achieved by increasing switching frequency.
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In this paper, we devised a pulse rate detection system to provide basic clinical index of cold-hot diagnosis of oriental medicine. The system consists of pulse signal detection, respiration signal detection, electrocardiograph detection, A/D conversion and computer system parts. We define a pulse rate by a pulse count to the respiration period inspiration pulse rate by a pulse count to the inspiration period, and expiration pulse rate by a pulse count to the expiration period. The clinical experiments for normal Person to evaluate the pulse rate detection system show the pulse/respiration ratio of 4.30
${\pm}$ 1.03, the pulse/inspiration ratio of 1.60${\pm}$ 0.32, the pulse/expiration ratio of 2.37${\pm}$ 0.75. -
In this paper, we devised pulse rate diagnosis database system for provide basic index of Cold-Hot diagnosis. The system consist of database part and pulse rate detection part that for detection pulse wave, respiration and ECG. The database is constructed windows95 platform using DAO(Data Access Object). Search algorithm used ISAM algorithm. The database consist of patient information and medical report for a subject and detected biological signals.