• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.407-410
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• 2002

As a part of electro-mechanical totally implantable artificial heart, a transcutaneous energy transmission system has been developed. By mutual magnetic induction between the first coil on the skin and the subcutaneously implanted second coil, the system transfers electrical power through the skin. This research aimed a minimizing the size of the implanted part as well as maximizing the transfer efficiency. When an air gap is 1$\sim$2cm, voltage gain and current gain low and it is hard to transfer energy due to large leakage flux. That is, the required input voltage and input current must be large compared with the output voltage and output current, respectively, This paper research the inverter topology and the control method in order to increase the voltage gain and the current gain. For this purpose, this inverter employs double tune to compensate the large leakage inductance of primary and secondary of the transcutaneous transformer. And the output energy of transcutaneous energy transmission system supply for Lithium-ion battery charger.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.80-82
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• 2002

To solve the difficulty in obtaining transmission routes and substation sites. increase the transmission capacity between generation sites and load centers. and enhance the stability of the power system. we have constructed and operated the 765kV double circuit transmission line(hereunder T/L) from the Dangjin thermal power plant and the Uljin nuclear power plant to the metropolitan. It makes it possible for us to accumulate know-how of the 765kV system that is the highest operating system level in Asia. As the second 765kV project, we are going to construct the 765kV single circuit T/L between Ansung and Gap yung. Because of the different electrical and mechanical characteristics. we are in need of different design technology. This paper presents the optimal design of 765kV single circuit transmission line after due consideration about the arrangement of conductors. the shape of a tower, insulation, etc.

• Journal of Magnetics
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• v.16 no.4
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• pp.374-378
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• 2011

Axial Field Permanent Magnet (AFPM) generators are widely applied for the small wind turbine because of the higher power density per unit weight than that of the conventional radial field generator. It is caused by the disc shaped rotor and the stator structures. The generally used AFPM generator, AFER-NS generator, is composed of the two side's external rotors and non-slotted stator without stator core. However, the output voltage and the output power are limited by the large reluctance by the long air-gap flux paths. In this paper, the design study of AFIR-S generator having double side's slotted stator core is accomplished to improve the output generation characteristics. The electromagnetic design analysis and the design improvement of the suggested AFIR-S generator are studied. Firstly, the electromagnetic design analysis was done to increase the power density. Secondly, the design optimizations of the rotor pole-arc ratio of permanent magnet are accomplished to increase the output power and to reduce the cogging torque. Finally, the output performances of AFER-NS and AFIR-S generator are compared with each other. For this study, 3D FEA is applied for the design analysis because of three dimensional electromagnetic structures.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.137-146
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• 2000

The stoichiometric mix of evaporating materials for he CuInS₂ single crystal thin films was prepared. To obtain the single crystal thin films, CuINS₂ mixed crystal was deposited on etched semi-insulator GaAs(100) substrate by the hot wall epitaxy(HWE) system. The source and substrate temperature were 640℃ and 430℃, respectively and the thickness of the single crystal thin films was 2 ㎛. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility deduced from Hall data are 9.64x10/sup 22//㎥ and 2.95x10/sup -2/ ㎡/V·s, respectively at 293 K. he optical energy gap was found to be 1.53 eV at room temperature. From the photocurrent spectrum obtained by illuminating perpendicular light on the c-axis of the thin film, we have found that the values of spin orbit coupling splitting ΔSo and the crystal field splitting ΔCr were 0.0211 eV and 0.0045 eV at 10K, respectively. From PL peaks measured at 10K, were can assign the 807.7 nm (1.5350 eV) peak to E/sub x/ peak of the free exciton emission, the 810.3 nm(1.5301 eV) peak to I₂ peak of donar-bound exciton emission and the 815.6 nm(1.5201 eV) peak to I₁ peak of acceptor-bound excition emission. In addition, the peak observed at 862.0 nm(1.4383 eV) was analyzed to be PL peak due to donor-acceptor pair(DAP).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.481-484
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• 1999

The undoped-InSe and Sn-doped InSe single crystals were grown by vertical Bridgman method and their properties were invesigated. These crystals were obtained by lowering the quartz ampoule for growth in the furnace and growth rate at optimum condition is 0.4mm/hr. The orientations and the crystallinites of these crystals were identified by X-ray diffraction(XRD), double crystal rocking curve(DCRC) and etch-pit density(EPD) measurements. From the Raman spectrum at room temperature, TO, LO modes together with their overtones and combinations were observed. Optical properties were investigated by photoluminescence at 12K and direct band gap of these crystals obtained from optical absorption spectrum. Compared with undoped-lnSe, electrical properties of Sn-doped InSe were increased and the electrical conductivity type were n-type. But electrical properties along growth direction of crystals and radial direction of wafer showed nearly uniform distribution.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2141-2143
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• 2000

In this paper, high concentration yield multi-discharge type ozonizer (MDO) of new discharge type using superposed silent discharge was designed and manufactured, MDO can be consisted with 3 kind of multi discharge type ozonizer (MDO) in accordance with power supply method that supplying power, which has 180[$^{\circ}$] phase difference, to 3 electrodes and double gap. At the moment, discharge characteristics and ozone generation characteristics of each MDO were investigated in accordance with quantity of supplied gas, the number of MDO, and the shapes of each MDO. In result, ozone generation characteristics of 17185[ppm] and 783[g/kWh] were obtained, and when ozone of 17185 [ppm] was in contact with dyeing water waste, decolorization characteristics was excellent, so it confirmed that MDO could be used as water environment improvement facility.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.3
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• pp.1050-1060
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• 1996

Recently, attention has been paid to the flame diagnostic by noncontact methods which dose not deform the flame shape. One of them is a method which is using the radical luminous intensity. Generally, this diagnostic method using radical luminous has been investigated its reliability by applying to laminar flame. This study, however, investigated each radical luminous signals through stocastical analysis like auto-correlation, cross-correlation, phase and coherence which were acquired from measuring radical luminous intensity of OH, CH, $O_{2}$, radicals in turbulent diffusion flame. To compare radical luminous intensity in flame with temperature, ion current and concentration , radious distribution of each properties was investigated and considered. In radical luminous intensity, correlation in the reaction zone of flame was higher than in correlation in combusted gas zone. And radious distribution of radical luminous intensity was corresponded with radious distribution of temperature, ion current and concentration. The result of the study confirms that a radical luminous flame diagnosis is possible in the turbulent diffusion flame.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.50-56
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• 2012

The Multi D.O.F spherical motor can drive rotating as well as tilting three degree of freedom with one motor. Existing three degree of freedom to drive with three motors that are connected by gears and belts, that will be too large size and big loss at gears and belts. So Reducing system size and improving efficient is using the Multi D.O.F spherical motor in three degree of freedom systems. For this reason, efficiency of Multi D.O.F spherical motor is one of the important performance indiccators. In this paper presented that how to improve the efficiency of the Multi D.O.F spherical motor. The fist of method is using the stator iron core's material with high permeability and resistivity for reducing the eddy current loss. However, it was the disadvatages of motor-making and economic. So author propose the resonable method of reducing the eddy current loss in the stator iron core. That is using the rotor with double-air gap.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.464-467
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• 1999

The undoped-InSe and Sn-doped InSe single crystals were grown by vertical Bridgman method and their properties were invesigated. The orientations and the crystallinites of these crystals were identified by X-ray diffraction(XRD), double crystal rocking curve(DCRC) and etch-pit density(EPD) measurements. From the Raman spectrum at room temperature, TO, LO modes and together with their overtones and combinations were observed. Optical properties were inves ated by PL at 12K and direct band gap of these crystals obtained from optical absorption spectrum. Compared with undo&-InSe, electrical properties of Sn-doped InSe were increased and the electrical conductivity type were n-type. But electrical properties along growth direction of crystals and radial direction of wafer showed nearly uniform distribution. The Zn diffusion mechanism in InSe could be explained by interstitial-substitutional and vacancy complex models and the activation energy of 1.15-3.01eV were needed for diffusion.fusion.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.160-162
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• 2003

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193nm) excimer laser. The substrate temperatures was $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}\;cm^{-3}\;and\;299\;cm^2V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;3.3973\;eV\;-\;(2.69{\times}10^{-4}\;eV/K)T^2/(T\;+\;463K)$. After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Zn}$, Vo, $Zn_{int}$, and $O_{int}$ obtained by PL measurements were classified as a donors or accepters type.