• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.786-794
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• 2022

Green ammonia is a promising renewable energy carrier. Green ammonia can be used in various energy conversion devices (e.g., engine, fuel cell, etc.). Ammonia has to be fed with hydrogen for start-up and failure protection of some energy conversion devices. Ammonia can be converted into hydrogen by decomposition and partial oxidation. Especially, partial oxidation has the advantages of fast start-up, thermally self-sustaining operation and compact size. In this paper, thermodynamics, start-up and operation characteristics of ammonia partial oxidation were investigated. O₂/NH₃ ratio, ammonia flow rate and catalyst volume were varied as operation parameters. In thermodynamic analysis, ammonia conversion was maximized in the O₂/NH₃ range from 0.10 to 0.15. Ammonia partial oxidation reactor was successfully started using 12 V glow plug. At 0.13 of O₂/HN₃ ratio and 10 LPM of ammonia flow rate, ammonia partial oxidation reactor showed 90% of ammonia conversion over commercial Ru catalyst. In addition, Increasing O₂/NH₃ ratio from 0.10 to 0.13 was more effective for high ammonia conversion than increasing catalyst volume at 0.10 of O₂/NH₃.

• Journal of Electrical Engineering and Technology
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• 제2권3호
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• pp.366-372
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• 2007

Joining thin aluminum alloy is difficult using most welding techniques. Many of the problems are associated with bum-through by the high heat input. Common welding techniques are TIG (Tungsten Inert Gas), MIG (Metal Inert Gas), and PULSE-MIG welding. The method provides more control of the heat balance in the welding arc by taking advantage of the different arc characteristics obtained with each of the two polarities. In this paper, we proposed a new welding method by control DSP 320C32, and the characteristic and experiment result-voltage, current, welding bead, and penetrations by this method are presented.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권12호
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• pp.567-572
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• 2005

Recently, application area of the thyristor is extends to power conversion systems, such as HVDC, BTB, SVC and FACTS. Therefore, reliability diagnostic technique on thyristor is needed to obtain stability and maintenance of power conversion systems. To measure the characteristics of the thyristor, test equipments which based on IEC 747-6 and KS C 7023 standard are needed. In this paper, we presents the design and manufacture of the test equipments for 6.5kV/4.2kA thyristor which used in thyristor valve of HVDC conversion systems by using test standard. Voltage, current, dv/dt and turn-off time test equipments were designed and manufactured. Each systems were made separately, but unity operation can possible.

• 전기학회논문지
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• 제65권3호
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• pp.520-525
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• 2016

In this paper, Characteristic of power conversion unit of a railway vehicles according to contact loss in feeding system that applied impedance of rigid conductor is analyzed. It applied impedance of rigid bar in modeling of electric railway system. Railway vehicles are performed of modeling based on the performance of the electric railway vehicle. Effects of the contact loss in the power conversion unit were analyzed via main transformer of railway vehicle, the input and output voltage characteristics of the converter through contact loss was generated after linking the vehicle with feeding system.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.229-230
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• 2012

Platinum (Pt) has been commonly used as a counter electrode material in dye-sensitized solar cells, because it has high catalytic activity and electric conductivity as well as chemical inertness with iodide electrolyte. However, Pt is too expensive to be commercialized. Therefore, in the present study, carbon black counter electrode with Pt and carbon nano tube (CNT) was investigated. The power conversion efficiency with Pt added carbon black electrode was lower than hat of pure Pt electrode which was 6.47 %. By adding 3 wt% Pt to the carbon black counter electrode, the power conversion efficiency was maximized at 5.88 %. On them, additional adding of 1 wt % CNT, the power conversion efficiency (${\eta}$)wasincreasedupto6.21%. The reason of power conversion efficiency improvement with a proper amount of Pt and CNT was examined by comparing the impedance properties measured using EIS.

• Journal of information and communication convergence engineering
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• 제21권4호
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• pp.316-321
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• 2023

In this study, we developed a conversion core that produces power by utilizing the unused magnetic field in a switchboard. The conversion core makes it possible to utilize power that is normally wasted. The conversion core is composed of a core, filter, and battery. A prototype was installed in a switchboard to conduct tests on the output, battery storage, and output boosting of multiple batteries. Energy was harvested from the magnetic field generated by a busbar of the switchboard, and the power conversion ratio of the core yielded 1.08-1.01 mW per 1 A of bus current. Supplying this technology to the market after further R&D and commercialization is expected to greatly assist in the dissemination of energy harvesting, which has not yet spread widely to the general public.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권11호
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• pp.753-759
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• 2004

This paper presents a modeling and simulation of a fuzzy controller for maximum power extraction of a grid-connected wind energy conversion system with a link of a rectifier and an inverter. It discusses the maximum power control algorithm for a wind turbine and proposes, in a graphical form, the relationships of wind turbine output, rotor speed, power coefficient, tip-speed ratio with wind speed when the wind turbine is operated under the maximum power control. The control objective is to always extract maximum power from wind and transfer the power to the utility by controlling both the pitch angle of the wind turbine blades and the inverter firing angle. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation method. The simulation results performed on MATLAB will show the variation of generator's rotor angle and rotor speed, pitch angle, and generator output.

• 전력전자학회논문지
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• 제13권3호
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• pp.196-205
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• 2008

고전압 DC 전원 응용에 사용되는 높은 입출력 전압 변환비의 특성을 가지는 새로운 극성 반전형 dc/dc 전력 변환 회로를 제안하였다. 제안안 회로의 특징은 기존회로보다 소자의 전압 스트레스가 감소된다. 제안한 회로의 동작원리를 분석하고 특징을 비교하였다. 제안한 회로의 타당성을 검증하기 위해 시뮬레이션결과와 실험결과를 비교 분석 하였다.

• Journal of Power Electronics
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• 제10권1호
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• pp.72-78
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• 2010

In this paper the operation of a double-fed wound-rotor induction machine, coupled to a wind turbine, as a generator at sub-synchronous speeds is investigated. A novel approach is used in the analysis, namely, the rotor power flow approach. The conditions necessary for operating the machine as a double-fed induction generator (DFIG) are deduced. Formulae describing the factors affecting the range of sub-synchronous speeds within which generation occurs are deduced. The variations in the magnitude and phase angle of the voltage injected to the rotor circuit as the speed of the machine changes to achieve generation at the widest possible sub-synchronous speed range is presented. Also, the effect of the rotor parameters on the generation range is presented. The analysis proved that the generation range could increase from sub-synchronous to super-synchronous speeds, which increases the amount of energy captured by the wind energy conversion system (WECS) as result of utilizing the power available in the wind at low wind speeds.

• 조명전기설비학회논문지
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• 제22권6호
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• pp.44-49
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• 2008

계약전력 산정 방법에서 적용되는 계약전력 환산율은 전력용변압기의 용량을 산정하는데 매우 중요한 기준이다. 본 연구에서는 AMR(자동검침시스템) 시스템에 의해 산업용전력사용고객을 대상으로 각 수용가 계약전력과 최근 5년 동안의 최대전력을 조사하였다. 조사된 자료의 전체 특징과 중심적인 경향을 알아보기 위해서 평균값 등의 특징파라메터를 분석하였고, 회귀분석을 통한 선형적인 방법과 비선형적인 방법으로 그 경향을 분석하였다. 따라서 산업용고객의 계약전력 결정에 필요한 계약전력환산율의 특성과 변압기최대이용률이 60[%] 이상인 고객을 중심으로 분석한 회귀분석 모형과의 특성을 비교하였다.