• 한방안이비인후피부과학회지
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• 제16권2호
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• pp.189-211
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• 2003

The clinical data and thermographic imaging were analyzed on the 38 cases of Bell's palsy who were treated admission in the Oriental Medicine Hospital of Wonkwang University from January 2002 to May 2003. 38 patients with Bell's palsy were within one week after the onset of the paralysis, and thermal type in the DITI were hypo or hyper generally. Nerve conduction test(ENOG and EMG) examined in two weeks after onset. We studied interaction effect between thermal type and paralysis grade on admission day. We studied each main effect ; paralysis grade on admission day - nerve conduction test, nerve conduction test - thermal type, thermal type - paralysis grade after 4 weeks, paralysis grade on admission day - paralysis grade after 4 weeks, sasang constitution - nerve conduction test. The following results were obtained that interaction effect between thermal type and paralysis grade on admission day showed no significance, each main effect ; paralysis grade on admission day - nerve conduction test, paralysis grade on admission day - paralysis grade after 4 weeks, showed significance, each main effect ; nerve conduction test - thermal type, thermal type - paralysis grade after 4 weeks, sasang constitution - nerve conduction test, showed no significance.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.255-258
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• 1996

A new low conduction loss, low cost zero-voltage-transition power factor correction circuit(PFC) is presented. Conventional PFC which consists of a bridge diode and a boost converter(one switch) always has three semiconductor conduction drops. Two switch type PFCs reduces conduction loss by reducing one conduction drop but the cost is increased because of increased number of active switches. The proposed PFC reduces conduction loss with one switch, which allows low cost. Conduction loss improvement is a little bit less than that of two switch type, but very close up. Operation and features are comparatively illustrated and verified by simulation and experimental results of 1 kW laboratory prototype.

• 전력전자학회논문지
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• 제19권2호
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• pp.173-183
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• 2014

In this paper, an analysis of power losses for the three-level T-type and neutral-point clamped (NPC) PWM inverters is presented, in which the conduction and switching losses of semiconductor devices of the inverters are taken into account. In the inverter operation, the conduction loss depends on the modulation index (MI) and power factor (PF), whereas the switching loss depends on the switching frequency. Power losses for the T-type and NPC inverters are analyzed and calculated at the different operating points of MI, PF and the switching frequency, in which the four different models of semiconductor devices are adopted. In the case of lower MI, the NPC-type is more efficient than the T-type, and vice versa. The validity of the power loss analysis has been verified by the simulation results.

• 한국태양에너지학회 논문집
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• 제37권5호
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• pp.77-84
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• 2017

The purpose of this paper is to propose the way of computing conduction time series factors (CTSF) using numerical method. After the accuracy of the numerical solution procedure being verified, the method is applied to the wall type 24 and roof type 14 of ASHARE to find the conduction time series coefficients, so called conduction time series factors. The results agree well with the values presented in the ASHRAE handbook. The method proposed can be easily applied to find unknown CTSF for more complex structures. It provides information about the temperature changes at a given location and time, thus validity of generated CTSF can be checked easily.

• 한국진공학회지
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• 제8권3A호
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• pp.187-193
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• 1999

In this study, PVDF thin films which show the excellent piezoelectricity and pyroelectricity, are prepared by PVD (physical vapor deposition) method, and thir electrical conduction phenomena for analyses of the electrical conduction mechanism and TSC (Thermally Stimulated Current) for identification of the behavior of conductive carriers are investigated. As a result of FT-IR(Fourier Transform Infrared Spectroscopy) spectra, the crystalline phase transforms $\alpha$ type into $\beta$ type with increasing electric field. From XRD (X-Ray diffraction) analyses patterns, the degree of crystallinity increases from 49.8% to 67%, as the substrate temperature increases from $30^{\circ}C$ to $80^{\circ}C$. As a result of electrical conduction phenomena, the electrical conduction mechanism of PVDF thin films is identified as ionic conduction mechanism. From TSC analyses, there are three peaks as P1, P2, P3 with increasing temperature, and with increasing substrate temperature, the peak temperature of TSC increases and the peak intensity of TSC decreases.

• 한국세라믹학회지
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• 제41권8호
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• pp.623-627
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• 2004

Ba가 첨가된 LaBaGa $O_4$ 층상 perovskite의 생성상과 전도거동에 대해 고찰하였다. LaBaGa $O_4$의 La-site에 20at% 이하의 $Ba^{2＋}$ 이온을 첨가한 조성은 $K_2$Ni $F_4$구조 사방정 단일상을 형성하였다. 건조분위기에서 L $a_{0.8}$B $a_{1.2}$G $a_{3.9}$는 높은 산소분압영역에서 산소이온전도와 hole(p-type)전도의 혼합전도를 나타내었다. 수증기분위기에서는 수증기가 산소빈자리로 유입되어 proton전도가 발생되었으며, 온도가 낮아질수록 총전도에 대한 proton 전도도의 기여가 증가하여 35$0^{\circ}C$ 이하의 온도에서는 proton 전도가 지배적인 전도를 나타내었다. Proton 전도에 대한 활성화 에너지는 0.72 eV였다.

• 한국전기전자재료학회논문지
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• 제15권3호
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• pp.220-226
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• 2002

Amorphous $Sb_{2-x}Bi_xTe_3$ (x = 0.0, 0.5 and 1.0) thin films were prepared by vacuum evaporation. The resistivity of 7he films decreases from 1.4{\times}10^{-2}$ to $8.84{\times}10^{-5}\Omega cm$ and the type of conductivity changes from p to n with the increase of the x value of the films. D.C. conduction studies on these films ate performed at various electric fields in the temperature range of 303-403 K. At low electric fields, two types of conduction mechanisms, i.e. the variable range hopping and the phonon assisted hopping are found to be responsible for the conduction, depending upon the temperature. The activation energy decreases from 0.082 to 0.076 eV in the temperature range of 303-363 K and from 0.47-0.456 eV in the second range of 363-403 K, indicating the shift of the Fermi level towards the conduction band edge and hence the change of the conduction from P to n type with the increase of the Bi concentration. Poole-Frankel emission dominates at high fields. The shape of the potential well of the localized centre is deduced and the mean free path of the charge carriers is also calculated.

• Journal of Advanced Marine Engineering and Technology
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• 제40권5호
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• pp.389-396
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• 2016

The theory of Fourier heat conduction predicts accurately the temperature profiles of a system in a non-equilibrium steady state. However, in the case of transient states at the nanoscale, its applicability is significantly limited. The limitation of the classical Fourier's theory was overcome by C. Cattaneo and P. Vernotte who developed the theory of non-Fourier heat conduction in 1958. Although this new theory has been used in various thermal science areas, it requires considerable mathematical skills for calculating analytical solutions. The aim of this study was the identification of a newer and a simpler type of solution for the hyperbolic partial differential equations of the non-Fourier heat conduction. This constitutes the first trial in a series of planned studies. By inspecting each term included in the proposed solution, the theoretical feasibility of the solution was achieved. The new analytical solution for the non-Fourier heat conduction is a simple exponential function that is compared to the existing data for justification. Although the proposed solution partially satisfies the Cattaneo-Vernotte equation, it cannot simulate a thermal wave behavior. However, the results of this study indicate that it is possible to obtain the theoretical solution of the Cattaneo-Vernotte equation by improving the form of the proposed solution.

• 전력전자학회논문지
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• 제27권6호
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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.

• 전기학회논문지P
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• 제58권4호
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• pp.377-384
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• 2009

In this paper, leakage current sensing module of SoC(System on Chip)type and real time monitoring system under consideration of electromagnetic interface in power trunk line are developed. The first, leakage current sensing module of SoC type under consideration of electromagnetic interface is developed, and the developed sensing module of SoC type is composed of leakage sensing part, power supply part, interface part, communication part, AD(Alternating current to Direct current)convert part and amplification part. And also the electromagnetic compatibility is evaluated by conduction and radiation of EMI(Electromagnetic Interference) for developed sensing module. The developed system can have confidence, stability and do energy saving under mixed electric circumstance of the low voltage communication device and high voltage equipment. The second, the real time remote monitoring system is developed using designed wire and wireless communication module with leakage current sensing module of SoC type. The developed real time remote monitoring system can monitor sensing state, occurrence state of leakage current and alarm for each step etc.. And the device configuration, PCB layout for leakage current sensing module of system on chip type and the experiment configuration in consideration of EMI are presented. Also the measurement results of conduction and radiation for EMI are presented.