• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.49-56
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• 2008

This paper introduces a compact analytical current conduction model of long-channel depletion-mode n-type nanowire field-effect transistors (NWFETs). The NWFET used in this work was fabricated with the bottom-up process and it has a bottom-gate structure. The model includes all current conduction mechanisms of the NWFET operating at various bias conditions. The results simulated from the newly developed NWFET model reproduce a reported experimental results within a 10% error.

• Journal of the Korean Ceramic Society
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• v.33 no.6
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• pp.645-652
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• 1996

The ionic conductivity of NASICON (Na Super Ionic Conductor) solid electrolyte was simulated by using Monte Carlo Method (MCM)based on a hopping model. We assumed that the conduction path of Na ions is Na1→mid-Na→Na2 where the mid-Na sites are shallow potential sites to induce 'a breathing-like movement' of Na ions in the NASICON framework. The minimum of charge correlation factor Fc and the maximum of appeared at nearby x=2.0 The occupancy of mid-Na site affected the depth of potential barrier and the conduc-tivity of the NASICON. At above x=0.3 ln σT vs. 1/T* plots have been shown Arrhenius behavior but in (VWfc)vs. 1/T* have been shown the Arrhenius type tendency at x=1 MCM results accorded with the experi-mental procedure. The role of mid-Na on Na+ ion conduction could be explained by an additional driving force and a breating-like movement model for motions of Na+ ions in the NASICON framework. As we couldn't clearly remarked the model which is the better it seems reasonable to conclude that these hypothesies are suitable to explain the FIC behavior at NASICON.

• Journal of Power Electronics
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• v.9 no.2
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• pp.275-287
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• 2009

This paper investigates analytical models of Conduction and Switching Losses (CASLs) of a matrix-Z-source converter (MZC). Two analytical models of the CASLs are obtained through the examination of operating principles for a Z-source inverter and ac-dc matrix converter respectively. Based on the two models, the analytical model of CASLs for a MZC is constructed and visualized over a range of exemplified operating- points, each of which is defined by the combination of power factor (pt) and modulation index (M). The model provides a measurable way to approximate the total losses of the MZC.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.588-593
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• 2007

The 600kJ class high temperature superconducting magnetic energy storage (HTS SMES) system is being developed by Korean Electrotechnology Research Institute (KERI). The system is operated in cryogenic temperature and high vacuum condition. The SMS magnet was cooled by conduction cooling method using a Gifford-McMahon cycle cryocooler. Thus, electric insulation design at cryogenic temperature and high vacuum is a key and an important element that should be established to accomplish compact design is a big advantage of HTS SMES. This paper describes the electric insulation design, fabrication and experimental results for a mini model of conduction cooled HTS SMES.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.593-600
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• 2016

The solar array regulator for low earth orbit satellites controls a operating point of solar array for suppling electric power to the battery and the other units. Because the control object is reversed, the new approach for large and small signal analysis is needed despite using buck-converter for power stage. In this paper, the steady state analysis of solar array regulator is performed in continuous conduction mode and discontinuous conduction mode, and the border condition for each mode is established. Also, the small signal model of solar array regulator is established in discontinuous conduction mode. Experiments are carried on in worst condition which the solar array regulator can face with discontinuous conduction mode. The results show that the solar array regulator is in stable.

• Progress in Superconductivity and Cryogenics
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• v.9 no.1
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• pp.32-36
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• 2007

The 600 kJ calss high-temperature superconducting(HTS) SMES(superconducting magnetic energy storage) system is being developed by Korean Electrotechnology Research Institute(KERI). The system is operated in cryogenic temperature and high vacuum condition. The SMES magnet was cooled by conduction cooling method using a Gifford-McMahon cycle cryocooler. Thus the electric insulation design at cryogenic temperature and high vacuum is a key and an important element. Because it accomplish compact design that is a big advantage of HTS SMES. This paper describes the electric insulation design, fabrication and experimental results for a mini model of conduction cooled HTS SMES.

• Journal of the Korean Ceramic Society
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• v.32 no.8
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• pp.957-965
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• 1995

The ionic conductivityof NASICON solid electrolytes was simulated by using Monte Carlo Method (MCM) based on a hopping model as functions of temoperature and composition. Two conduction paths were used : jumping from Na1 to Na2 and jumping from Na1 to Na2 and jumping from Na2 to Na2. Vacancy availability factor, V was affected by composition, temperature and the conduction paths. For β"-Alumina, it was known that the minimum of charge correlation factor, fc appears at the composition, p=0.5, but there was not shown the minimum of fc for NASICON. When the NASICON composition, x, approaches 2.5, the curve of In σT vs. 1/T* was shown Arrhenius behavior and also In (VWfc) was a linear function of 1/T*. The results of simulations on the considered conduction paths didn't agree with the experimental results. Thus it will be necessary to include the another Na sites as mid-Na site on the conduction path to obtain the better results.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.684-690
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• 2008

In most engineering applications related with the heat conduction phenomena, a conventional Fourier heat conduction equation has been successfully applied and it has supplied quite reasonable results. However, it is well known that the Fourier heat conduction equation is failed in the application to the extremely small space and short time, in other words, a nano-scale system and a pico-second time. In this study, non-Fourier effect was evaluated in the heat conduction by considering the concept of a phase lag model. The results show the existence of a heat wave, which means that the heat is transferred with a finite speed while an infinite speed of heat transfer is assumed in the conventional Fourier heat conduction. In addition, the copper and the gold are tested to evaluate the phase lag time between the heat flux and the temperature gradient. The results show that the gold has the heat wave speed faster than that of the copper consistent with the prediction based on an actual experiment.

• Journal of the Ergonomics Society of Korea
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• v.19 no.2
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• pp.63-74
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• 2000

This paper is to clarify a thermal physiological index that can account for the effects of local thermal environment. For this purpose two young female subjects exposing themselves to the above while sitting on a chair, sitting on the floor and lying on the floor were measured. These three representative postures accompanied the different contact surface areas, thereby the heat conduction rate between the floor and subject was quantitatively measured for each posture. It made the present study deal with the effect of heat conduction concerning the modified mean skin temperature and finally propose new weighting coefficients for the mean skin temperature calculation based on the Hardy & DuBois' formulas. In order to verify the proposed model, the experiment was carried out using a floor heating system. The comparison between the experimental result and prediction revealed that the proposed model should be about 10% more accurate than the conventional one in the case of lying on the floor which the heat conduction effect becomes important.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.917-921
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• 2013

This paper have analyzed the change of breakdown voltage for conduction path of double gate(DG) MOSFET. The low breakdown voltage among the short channel effects of DGMOSFET have become obstacles of device operation. The analytical solution of Poisson's equation have been used to analyze the breakdown voltage, and Gaussian function been used as carrier distribution to analyze closely for experimental results. The change of breakdown voltages for conduction path have been analyzed for device parameters such as channel length, channel thickness, gate oxide thickness and doping concentration. Since this potential model has been verified in the previous papers, we have used this model to analyze the breakdown voltage. Resultly, we know the breakdown voltage is greatly influenced on the change of conduction path for device parameters of DGMOSFET.