• Korean Journal of Materials Research
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• v.20 no.8
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• pp.429-433
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• 2010

In this study, activated carbon (AC) as a carbon source was modified with different concentrations of cobalt chloride ($CoCl_2$) to prepare a Co-AC composite, and it was used for the preparation of Co-AC/$TiO_2$ composites with titanium oxysulfate (TOS) as the titanium precursor. The physicochemical properties of the prepared Co-AC/$TiO_2$ composites were characterized by $N_2$ adsorption at 77 K, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The photocatalytic treatments of organic dyes were examined under an irradiation of visible light with different irradiation times. $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine AC, which was $389\;m^2/g$. From the XRD results, the Co-AC/$TiO_2$ composites contained a mixturephase structuresof anatase and rutile, but a cobalt oxide phase was not detected in the XRD pattern. The EDX results of the Co-AC/$TiO_2$ composites confirmed the presence of various elements, namely, C, O, Ti, and Co. Subsequently, the decomposition of methylene orange (MO, $C_{14}H_{14}N_3NaO_3S$) and rhodamine B (Rh.B, $C_{28}H_{31}ClN_2O_3$) in an aqueous solution, respectively, showed the combined effects of an adsorption effect by AC and the photo degradation effect by $TiO_2$. Especially, the Co particles in the Co-AC/$TiO_2$ composites could enhance the photo degradation behaviors of $TiO_2$ under visible light.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.230-234
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• 1995

The loss of offsite power test was successfully performed on YGN 4 to demonstrate that the reactor can be shutdown and the RCS can be maintained in a hot standby condition following a loss of all offsite Alternating Current (AC) power. Following the loss of main generator and all offsite AC power, the ensile emergency diesel generators were automatically started and the plant was stabilized via natural circulation. Plant conditions were maintained in hot standby for at least 30 minutes before offsite power was restored. Thus, the capability of equipment, controls and instrumentation necessary to remove decay heat from the core using only ensile emergency power was demonstrated, thereby satisfying all objectives and acceptance criteria of the test.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.500-503
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• 1991

Fuel cells power generating system converts the chemical energy of a fuel directly into electrical energy. The merits of fuel cells power generating system are pollution free and high energy conversion efficiency. Fuel cells power generating system includes the DC/AC converter. DC source obtained from stack is converted to the constant AC voltage or current by the inverter. In this paper, the power control techniques for the fuel cells power generating system are described.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1991.10a
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• pp.59-63
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• 1991

Fuel cells power generating system converts the chemical energy of a fuel directly into electrical energy. The merits of fuel cells power generating system are pollution free and high energy conversion efficiency. Fuel cells power generating system includes the DC/AC converter. DC source obtained from stack is converted to the constant AC voltage or current by the inverter. In this paper, the power conditioner for the fuel cells power generating system are discribed. Some experiments are performed, for the power conversion system. The results show that the implimented experimental system may be applied to the practical fuel cells power generating system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.250-253
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• 2007

This paper presents a new sustain driver employing energy recovery function to minimize power losses transpired during the operation of plasma display panel. The proposed circuit uses the resonance between the equivalent capacitance of panel and an external inductor to provide/recover energy to/from the panel. The proposed circuit can save the system cost compared with the conventional one, and has high-performance in energy recovery. To verify the validity of the proposed circuit, we implemented experiments based on 7.5 inch AC-PDP.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.174-176
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• 2018

도서 및 산간지역에 필요한 독립형 마이크로그리드는 디젤발전, 태양광발전 및 에너지저장장치 등으로 구성된다. 독립형 마이크로그리드내의 급격한 부하 변동, 분산형전원의 발전량 변동과 같은 문제로 인해 교류계통의 전압과 주파수가 변동한다. 특히, 독립형 마이크로그리드간에 전력을 주고받는 상황에서는 상호간의 교류전압과 주파수를 적절히 조절해야 할 필요가 있다. 본 논문에서는 독립형 마이크로그리드 간에 전력을 주고받을 시, 에너지 라우터(Energy Router)라는 기기를 이용하여 통신을 사용하지 않고 자율 분산 제어방법을 통해 계통 전압과 주파수를 제어하는 방법을 제안한다. 에너지 라우터는 AC/AC 컨버터를 사용하여 전력을 상호 간에 전달한다. 시뮬레이션 프로그램을 이용하여 부하 변동 및 분산형전원의 발전량 변동 등을 모의하고 에너지 라우터의 유효성을 검증한다.

• Journal of Power Electronics
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• v.6 no.3
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• pp.205-213
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• 2006

A cost-effective magnetic-coupled AC-PDP sustain driver with low switching loss is proposed. The transformer reduces current stress in the energy recovery switches which affects circuit cost and reliability. The turns-ratio can be used to adjust the sustain pulse slopes which affect gas discharge uniformity. Dividing the recovery paths prevents abrupt changes in the output capacitance and thereby switching losses of the recovery switches is reduced. In addition, the proposed circuit has a more simple structure because it does not use the recovery path diodes which also afford a large recovery current. By reducing the current stress and device count in the energy recovery circuit, the proposed driver may have decreased circuit cost and improved circuit reliability.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.255-256
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• 2014

최근 환경 문제가 사회적으로 대두됨에 따라 탄소배출권 제도에 대한 관심이 증대되면서 Net Zero Energy Building(NZEB)에 대한 관심 역시 커지고 있다. NZEB는 주로 태양광을 에너지원으로 이용하며, 더 효율적인 에너지 사용을 위해 에너지 저장장치(SIU)를 이용하는데 이 두 요소들은 DC전압을 출력으로 갖고 있으며, NZEB의 특성상 외부 AC그리드와 연결된 양방향 AC/DC컨버터의 사용량이 적기 때문에 건물 내 배전을 DC로 할 경우 더 효율적인 에너지 사용이 가능하다 본 논문은 기존 DC배전의 구조에 대해 살펴보고, 여기에 Renewable-Storage Connecting Unit(RSCU)을 더해 NZEB에서 에너지 사용의 효율성을 높이는 방법에 대해 연구하며, 또한 그 시스템 제어 방법에 대해 연구한다.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.372-375
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• 1995

The magnetization pattern of the central cross section deduced from the ac susceptibility measurement is described with an analytical function. The function is based on a charge-free configuration. The thickness of the $^{\circ}$ wall lying in a (100) plane and the wall energy are calculated analytically. Total energy of the domain structure has been minimized with Ritz's method. As the result of the minimization, the energy density of the $^{\circ}$ wall lying in a (100) plane is $0.58\;erg/cm^{2}$ and the one for a (110) plane is $1.18\;erg/cm^{2}$. Thicknesses of these walls are calculated numerically. Also, the calculation indicates there is a small central domain at the cross section without applied current. With the ac susceptibility measurement the existence of the domain without current can be identified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.234-240
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• 2019

In this work, the magnetic arc reduction phenomena encountered in AC relay contacts were analyzed. To this end, arc duration, instantaneous voltage, and current changes due to changes in the magnetic field were observed. The arc generated at the contact point was affected by the magnitude of the applied magnetic field; the voltage and current waveforms rapidly intersected, resulting in a decrease in arc duration and arc energy. Furthermore, the orientation of the N pole of the magnetic field was found to play a role in the effectiveness of potential arc prevention.