• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.811-813
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• 2003

We investigated the electrical properties of self-assembled (4,4'-Di(ethynylphenyl)-2'-nitro-1-thioacetylbenzene), which has been well known as a conducting molecule having possible application to molecular level negative differential resistance(NDR)[1]. Generally, the phenomenon of NDR can be characterized by the decreasing current with the increasing voltage[2]. To deposit the SAM layer onto gold electrode, we transfer the prefabricated nanopores into a 1mM self-assembly molecules in THF solution. Au(111) substrates were prepared by ion beam sputtering method of gold onto the silicon wafer. As a result, we measured the voltage-current properties and confirmed the negative differential resistance properties of self-assembled organic thin film and measured, using Scanning Tunneling Microscopy(STM).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.51-56
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• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2002.11a
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• pp.307-312
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• 2002

For accuracy of an experiment, measure changing of grounding resistance by short period after construction and investigated the efficiency of grounding's different methode of parallel connection. We could confirm on measurement's accuracy, error through comparing the theoretical value and measured value. Therefore, reduction ratio can be expected from execution measurement to receive a target resistance value. By the result, we could evaluate the method of rod grounding electrode's proper execution

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.3
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• pp.267-273
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• 1992

An advanced on-resistance model of VDMOS devices in the low voltage regimes is proposed and verified by 2-D device simulations. The model considers the lateral gaussian doping profiles in the channel region and exact current spreading angles in the epitaxial layer for both linear and cellular geometries by employing the conformal mapping, It is found out that the on-resistance of low voltage VDMOS may be overestimated considerably if it is analyzed by the conventional method. The 2-D device simulation results show that the proposed model is valid for the VDMOS devices in the low voltage regimes.

• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.38-42
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• 2023

The evaluation of no-insulation (NI) high-temperature superconducting (HTS) typically uses the lumped equivalent circuit (LEC) model. Constant parameters in the NI HTS LEC model accurately predict voltage and central magnetic field at currents below the critical current. However, it is difficult to find constant circuit parameters that simultaneously satisfy the measured voltage and magnetic field under overcurrent conditions. Recent research highlights changes in contact resistance during transient conditions, which may impact power loss estimation in NI HTS coils. Therefore, we confirm the influence of contact resistance changes on loss calculation in the transient state for NI HTS coil. To achieve this, we introduce a measurement data analysis method based on the LEC model and compare it with the LEC model using constant circuit parameters.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.73-78
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• 2016

3phase induction motor consumes 40% of national electric power. so It is one of the most important electric device for the national power policy. The efficiency measurement is carried out by IEC standards. After the temperature rise test, It's difficult to measure the winding resistance immediately. because of inertia and power cut-off time. Therefore, IEC standards suggest the measurement time. But during the measurement time, the winding temperature cools down. It causes the value of winding resistance is variable. Several conditions which possibly occurred by the measurement time of IEC 60034-1 are suggested. and The efficiency evaluation of 3phase induction motors is carried out by IEC 60034-2-1 with the several conditions. As the results, we find out the winding resistance rapidly goes down within 15 sec. so It proves that the winding resistance should be measured within 15 sec. for the efficiency evaluating of 3phase induction motor.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.403-406
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• 2005

Precise measurement of extremely low resistance shunt is important for characterization and calibration of high current instruments. We tested resistance measurement method for extremely high current shunt (up to 140 kA), where resistance is determined by precise measurement of voltage drop at 10 A test current in the frequency range of 40 Hz to 10 kHz. For the extremely low ac voltage to be precisely measured, a verification of the measurement method was also carried, where the inherent noise is systematically evaluated. The measurement uncertainty was estimated to be $1\;\%\;at\;95\;\%$ confidence level (k=2) for about 50 $\mu\Omega$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.198-201
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• 1997

The new system for identification of organic vapours and analysis method of mechanism between organic vapours and sensitive materials were attempted using the resonant resistance and resonant frequency of Quartz Crystal Analyzer (Q. C. A.). The resonant resistance shift means rheological changes in sensitive LB films occurred by the adsorption of organic vapours, while the resonant frequency shift represent the mass of organic vapour loaded in or on the sensitive LB films. It is thought that we can obtain more accurate response mechanism of organic vapour using the resonant frequency and resonant resistance diagram. The polymeric sensitive material were quantitively depositied using the LB method. In the experimental results, the adsorption behavior of organic vapour response can be decided by two type ; surface adsorption and penetration into sensitive material. Organic vapours had different positions in the Frequency-Resistance (F-R) diagram as to the kinds and concentrations of organic vapours. Thus F-R diagram can be applied to the development of one channel gas sensing system using the Quartz Crystal Analyzer.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1778-1783
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• 2009

Ground impedance for the large grounding system is measured according to the IEEE Standard 81.2 which is based on the revised fall-of-potential method of installing auxiliary electrode at a right angle. When the auxiliary electrodes are located at an angle of $90^{\circ}$, the ground impedance inevitably includes the error due to earth mutual resistance. In this paper, in order to accurately measure the ground impedance of vertically-driven ground electrodes, error rates due to earth mutual resistance are evaluated by ground resistance and ground impedance measuring devices and compared with calculated values. As a result, the measured results are in good agreement with the computed results considering soil layer with different resistivity. The error rates due to earth mutual resistance decrease with increasing the length of ground electrode in the case that the ratio of the distance between the ground rod to be measured and the auxiliary electrodes to the length of ground electrode(D/L) is same. The ground impedance should be measured at the minimum distance between the auxiliary electrodes that will have an estimated measurement accuracy due to earth mutual resistance.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.8
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• pp.438-444
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• 2000

We report the effects of etch process parameters on the ohmic contact formation in the plasma etching of GaN. Planar inductively coupled plasma system with $CH_4/H_2/Ar$gas chemistry has been used as etch reactor. The contact resistance and the specific contact resistance have been investigated using transfer length method as a function of RF bias power and %Ar gas concentration in total flow rate. AES(Auger electron spectroscopy) analysis revealed that the etched GaN has nonstoichiometric Ga rich surface and was contaminated by carbon and oxygen. Especially large amount of carbon was detected at the sample etched for high bias power (or voltage) condition, where severe degradation of contact resistance was occurred. We achieved the low ohmic contact of $2.4{\times}10^{-3} {\Omega}cm^2$ specific contact resistance at the input power 400 W, RF bias power 150 W, and working pressure 10mTorr with 10 sccm $CH_4$, 15 sccm H2, 5 sccm Ar gas composition.