• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권11호
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• pp.555-561
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• 2001

In this paper, the low power (1.5 W) solenoid-type magnetic thin-film transformers utilizing a $Ni_{81}Fe_{19)$ core material were designed and fabricated for 5 MHz-drive DC-DC converter application. The $20\mum$ thick copper films were used as the coils. The transformers fabricated in this work have the sizes of $3.08 mm\times25.5 mm\; and\; 6.15 mm\times12.75 mm.$ The optimum design of solenoid-type magnetic thin film transformers was performed utilizing the conventional equations, a Maxwell computer simulator (Ansoft HFSS V7.0 for PC), and parameters obtained from the magnetic properties of NiFe magnetic core materials. frequency characteristics of inductance, dc resistance (R), coupling factor (k) and gain of developed transformers were measured using HP4194A impedance and gain-phase analyzer. The fabricated transformers with the size of $6.15 mm\time12.75 mm$ exhibit the inductance of $0.83 \muH$, the dc resistance of $2.3\Omega$$\Omega$, the k of 0.91 and the gain of -1 dB at 5 MHz, which show the comparable results to those reported in the recent literatures. The measured high-frequency characteristics for the fabricated transformers agreed well with those obtained by theoretical calculations .

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.853-855
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• 1998

The electrical resistivity and mechanical properties of the hot-pressed and annealed ${\beta}$-SiC+39vol.%$ZrB_2$ electroconductive ceramic composites were investigated as a function of the liquid forming additives of $Al_{2}O_{3}+Y_{2}O_{3}$(6:4wt%). In this microstructures. no reactions were observed between $\beta$-SiC and $ZrB_2$, and the relative density is over 97.6% of the theoretical density. Phase analysis of composites by XRD revealed mostly of a $\alpha$-SiC(6H, 4H), $ZrB_2$ and weakly $\beta$-SiC(15R) phase. The fracture toughness decreased with increased $Al_{2}O_{3}+Y_{2}O_{3}$ contents and showed the highest for composite added with 4wt% $Al_{2}O_{3}+Y_{2}O_{3}$ additives. The electrical resistivity increased with increased $Al_{2}O_{3}+Y_{2}O_{3}$ contents because of the increasing tendency of pore formation according to amount of liquid forming additives $Al_{2}O_{3}+Y_{2}O_{3}$. The electrical resistivity of composites is all positive temperature coefficient resistance(PTCR) against temperature up to $700^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1992년도 추계학술대회 논문집
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• pp.114-117
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• 1992

본 논문에서는 자기적분형 자계센서의 설계방법과 교정방법을 제안하고, 파도대전류에 의하여 형성되는 자계에 대한 거리-응답 특성시험과 주파수 변화에 대한 응답도의 측정을 수행하였다. 자기적분형 센서는 적분저항의 증가와 더불어 감지전압은 상승하였으나 감쇠시간은 줄어드는 특성을 나타내었다. 또한 전기적 등가회로를 구성하여 이론적으로 해석 한 바 실험결과와 잘 일치하였다.

• 전기학회논문지
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• 제57권6호
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• pp.1022-1025
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• 2008

This paper presents the generation of the high voltage squarewave pulse using distributed RLC circuit. The demonstrated test was performed with the distributed RLC circuit which consists of the resistance, the inductance and the capacitance. Pspice simulation was also conducted about the experiment circuit. The result of the experiment was in good agreement with the result of the simulation. Theoretical analysis of the initial peak value at the squraewave pulse was derived from the results of the experiment and simulation. Additionally, the characteristics of the time delay was analyzed about the spherical gap switch and the surface discharge gap switch, respectively. It is concluded that the surface discharge gap switch is better than the spherical gap switch to reduce the time delay.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2002년도 학술대회논문집
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• pp.293-296
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• 2002

This paper describes the instantaneous current resultant type load parallel high frequency resonant inverter consisting of three unit half-bridge serial and parallel resonant inverter can be used as power source of induction heating. This proposed inverter can reduce distribution of the switching current because of using the current of serial resonant circuit to the input current of the parallel one. The analysis of the proposed circuit is generally described by using the normalized parameters. Also, the principle of basic operating and the its characteristics are estimated by the parameters such as switching frequency($\mu$), load resistance(λ). Experimental results are presented to verify theoretical discussion. This proposed inverter will can be practically used as a power supply in various fields as induction heating application, DC-DC converter etc.

• 전기학회논문지
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• 제59권6호
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• pp.1103-1108
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• 2010

A grounding electrode has the transient grounding impedance characteristics against lightning surges. So the performance of grounding electrodes should be evaluated as a grounding impedance as well as the ground resistance. The frequency-dependent grounding impedance is varied with the shape and size of grounding electrode and is divided into both inductive and capacitive behaviors. This paper presents a theoretical analysis for the grounding impedance determined by the size of grounding electrode using the distributed parameter circuit model. EMTP and Matlab programs were used in calculating the frequency-dependent grounding impedances of vertical grounding electrodes. It was found that the frequency-dependent grounding characteristics of vertical grounding electrodes are characterized by the distributed parameters which are changed in the dimension of grounding electrodes.

• 한국전기전자재료학회논문지
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• 제21권1호
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• pp.23-28
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• 2008

In this paper, transient characteristics of the Punch Through Insulated Gate Bipolar Transistor (PT-IGBT) have been studied. On the contrary to Non-Punch Through Insulated Gate Bipolar Transistor(NPT-IGBT), it has a buffer layer and reduces switching power loss. It has a simple drive circuit controlled by the gate voltage of the MOSFET and low on-state resistance of the bipolar junction transistor. The transient characteristics of the PT-IGBT have been analyzed analytically. Excess minority carrier and charge distribution in active base region, the rate of anode voltage with time are expressed analytically by adding the influence of buffer layer. The experimental data is obtained from manufacturer. The theoretical predictions of the analysis have been compared with the experimental data obtained from the measurement of a device(600 V, 15 A) and show good agreement.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.7-10
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• 2002

We designed the flyback planar transformer, which had 8W capacity, with 70V input voltage and 8.2V output voltage for the establishment of design method and the confirmation of application possibility. The numerical value of inductance measured under the switching frequency of 120 kHz was 1650 ${\mu}H$, which was the inductance efficiency of 85~87% against theoretical value. The A.C. resistance of primary and secondary coil was 4.2 ${\Omega}$ and 0.25 ${\Omega}$ respectively. On the other hand, the quality factor for each wound numbers showed quite a high value of 158 and 75 respectively. And the Coupling Factor was 0.96~0.97 under 120 kHz switching frequency. And the shape of the output wave of the planar transformer at 70V input voltage was a stable square wave.

• 전기학회논문지
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• 제58권10호
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• pp.1861-1868
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• 2009

A ground electrode subjected to lightning surge current shows the transient impedance behaviors. The ground electrode for protection against lightning should be evaluated in view of the transient grounding impedance and conventional grounding impedance, not ground resistance. The transient impedance characteristics of ground electrodes are influenced by the shape of ground electrode and the soil characteristics, as well as the waveform of lightning surge current. In order to propose a simulation method of analyzing the transient impedance characteristics of the grounding system in practical use, this paper suggests a theoretical analysis method of distributed parameter circuit model to simulate the transient impedance characteristics of counterpoise subjected to lightning surge current. EMTP and Matlab programs were employed to compute the transient grounding impedances of three counterpoises with different lengths. As a consequence, the simulated results using the proposed distributed parameter circuit model are in good agreement with the measured results.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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• pp.88-91
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• 2009

For lightning currents, a grounding system shows the transient grounding impedance characteristics. A grounding system for protection against lightning should be evaluated by the transient grounding impedance, not it's ground resistance. The transient grounding impedance varies with the shape of ground electrode and earth characteristics as well as the waveform of lightning surge current. For the analysis and practical use of transient grounding impedance, the characteristics of transient grounding impedance should be analyzed theoretically and this paper suggests the theoretical analysis for the transient grounding impedance of counterpoise by using the distributed parameter circuit model. EMTP and Matlab are used to simulate the distributed parameter circuit model of counterpoise and the adequacy of the distributed parameter model of counterpoise is examined by comparing the simulated results with the measured results.