• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1525-1527
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• 1997

We deposited maleate copolymer films by using Langmuir-Blodgrtt(LB) method. The deposition status of LB films were verified by the measurement of capacitance which was increased with the number of layers. And, we have investigated anisotropy electrical conduction characteristics of maleate copolymer LB films by I-V measurement for perpendicular direction and horizontal direction.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.1
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• pp.13-18
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• 2000

We have fabricated LB ultra-thin films of maleate system by LB technique and evaluated the deposited status of LB ultra-thin films by I-V characteristics such as capacitance. It was found that the thickness of LB ultra-thin per layer is $27~30[{\AA}]$ by XRD. And, we have known that the conductivity along the horizontal direction of LB ultra-thin films was about $10^{-8}[S/cm]$, it corresponds to the semiconducting materials. Also, the I-V characteristics along the vertical direction of LB ultra-thin films was dominated by Schottky type current, the activation energy obtained by current-temperature characteristics was about 0.84[eV] and the conductivity was about $10^{-14}[S/cm]$, it corresponds to the insulator. And, the anisotropic conduction mechanism of the LB ultra-thin films in vertical direction and horizontal direction is determined by the hydrophilic group and the hydrophobic group in LB ultra-thin films. The above results are applicable to the semiconductor devices such as switching device, which function at the molecular level.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.729-732
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• 2001

In this study, the effect of oxygen partial pressure on the electrical properties of vanadium oxide(VO$_{x}$) thin films were investigated. The thin films were prepared by r.f. magnetron sputtering from V$_2$O$_{5}$ target in a gas mixture of argon and oxygen. The oxygen partial pressure ratio is changed from 0% to 8%. I-V characteristics were distinguished between linear and nonlinear region. In the low field region the conduction is due to Schottky emission, while at high fields it changes to Fowler-Nordheim tunneling type conduction. The conductivity measurements have shown an Arrhenius dependence of the conductivity on the temperature.ure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.34-37
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• 1992

In this paper, the $(SrPb)(CaMg)TiO_3$-xBi_2O_3{\cdot}3TiO_2$ ceramics with paraelectric properties were fabricated by the mixed oxide method. In order to investigate the behavior of charged particles, the characteristics of electrical conduction and thermally stimulated current were measured respectively. As a result on characteristics of the electrical conduction, the leakage current was increased as measuring temperature was increased. At room temperature, the conduction current was divided into the three steps as a function of DC electric field. The first step was Ohmic region due to ionic conduction, below 15[kV/cm]. The second step was showed a saturation which seems to be related to a depolarizing field occuring in field-enforced ferroelectric phase, between 15[kV/cm] and 40[kV/cm]. The third step was attributed to Child's law related to spare charge which injected from electrode, above 40[kV/cm]. Thermally stimulated currents(TSC) spectra with various biasing fields exhibited three distinguished peaks that were denoted as ${\alpha}$, ${\alpha}'$ and ${\beta}$ peak, each of which appeared at nearby -30, 20 and 95[$^{\circ}C$] respectively. It is confirmed that the a peak was due to trap electron trapped in the grainboundary, and ${\alpha}'$ peak that was observed above only 1.5[kV/mm] was attributed to field-enforced ferroelectric polarization. The origin of ${\beta}$ peak was identified as ion migration which caused the degradation.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1503-1506
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• 1997

The main fault in this interface is that power cable insulating materials are mainly composed of a double layered structure, XLPE/EPDM laminates in cable joint. In this paper, we instituted the interface of normal and degassed XLPE/EPDM and then investigated the breakdown and conduction characteristics as a function of heat treatment time. The results showed that conduction and breakdown strength was influenced by volatile crosslinking by-products which remained inside the insulating material during the production of XLPE and EPDM, especially during heat treatment process. And micro voids and surface roughness also influenced the conduction current and breakdown strength.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1422-1424
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• 2002

EVA-OH (Ethylene-vinyl acetate-vinyl alchol terpolymers) were prepared by using the transesterification reaction between ethylene-vinyl acetate copolymer and alchol. Structural and thermal analyses were accomplished with FTIR and DSC. Space charge behaviors of EVA-OH were investigated using PEA method. Electrical conduction currents were also measured. As the increase of conversion rate, melting point increased and we could observe changes in space charge distributions and the increase of electrical conduction currents of EVA-OH.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1111-1113
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• 1995

To improve latch up characteristics of IGBT, this paper proposed new structure with reverse channel. IGBT proposed by this paper were designed on SOI substrate, $p^+$-substrate, and $n^+$-substrate, respectively. As a result of the simulation, we had achieved high latch up voltage and high conduction current density at IGBT with proposed structure. Latch up voltage of Conventional IGBT was 2.5V but IGBT with proposed structure was latched up at $5{\sim}94V$, respectively. And was showed high conduction current desity($10^4{\sim}10^7A/cm^2$)

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.6
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• pp.489-497
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• 2022

This work investigates the commutation characteristics of the current flowing through an electrical-contact-type switch to the semiconductor switch branch during the breaking operation of hybrid DC switchgear. A simple, reliable, low-cost natural commutation method is proposed, and the current commutation characteristics are analyzed in accordance with the conduction voltage drop of the semiconductor switch branch through experiments. A prototype 400 V/10 A class natural commutation type hybrid DC switchgear is set up. Its performance is verified, and its characteristics are analyzed.

• Journal of Power Electronics
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• v.7 no.1
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• pp.55-63
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• 2007

This paper proposes a simple unity power factor zero-voltage-transition (ZVT) pulse-width-modulated (PWM) single-phase rectifier, which features reduced switching and conduction losses. The switching loss reduction is achieved by a simple auxiliary commutation circuit, and the conduction loss reduction is achieved by employing a single-stage converter, rather than a typical double-stage converter comprising of a front-end rectifier and a boost rectifier. Furthermore, thanks to good features such as a simple PWM control at constant frequency, low switch stress, low Var rating of commutation circuits, and simple power circuit structure, it is suitable for high power applications. The principles of operation are explained in detail, and a major characteristics analysis and the experimental results of the new converter are also included in this paper.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.3
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• pp.409-419
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• 1994

This paper deals with the design criteria and conduction noise reduction of electronic ballast system which is based on half-bridge series inverters. The system is theoretically analyzed in six modes and operating frequency range is selected to obtain the high efficacy and no sound noise. It is proposed the criteria for determining the values of L and C which are the dey points in system design Because of high operating frequency, electromagnetic noise, especially conduction noise, is a serious problem in electronic ballasts. To reduce the conduction noise, the operation and attenuation characteristics of noise filter are analyzed and the method to determine the values of filter elements is proposed. Also, the parasitic components of the inductor and capacitor are taken into consideration in filter analysis. Digital simulations and experiments are carried out to prove the theoretical results. And perfor mances of the system are verified through tests.