• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.205.2-205.2
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• 2016

The emission test a domestic fabricated cathode is conducted using an easy-replaceable-emitter-type test bench. A simple cylindrical button type cathode is dropped vertically into a cathode cup holder. The cathode is heated by a tungsten wire heater located around the cup holder. The cathode temperature is measured by an optical pyrometer. A high voltage pulse power supply gives the anode-cathode gap voltage up to 20 kV with the pulse width of 15 us. The emitted current from the cathode is captured at a faraday cup and is measured using current transformer and oscilloscope. The test bench is installed in the vacuum chamber with easy access door and, therefore, the cathode can be easily replaceable. We confirmed the emission current density of $15A/cm^2$ and $80A/cm^2$ with a domestic fabricated B-type cathode and a Scandate cathode, respectively. The detailed test result for the cathode will be presented.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.1-4
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• 2008

Fuel cells have the potential of providing several times higher energy storage densities than those possible using current state-of-the-art lithium-ion batteries, but current energy density of fuel cell system is not better than that of lithium-ion batteries. To achieve the high energy density, volume and weight of fuel cell system need to be reduced by miniaturizing system components such as stack, fuel tank, and balance-of-plant. In this paper, the thin flexible PCB (Printed circuit board) is used as a current collector to reduce the stack volume. Two end plates are made from light weight aluminum alloy plate. The plate surface is wholly oxidized through the anodizing treatment for electrical insulation. The opening rate of cathode plate hole is optimized through unit cell performance measurement of various opening rates. The performances are measured at room temperature and ambient pressure condition without any repulsive air supply. The active area of MEA is 10.08 $cm^2$ and active area per a unit cell is 1.68 $cm^2$. The peak power density is about 210 mW/$cm^2$ and the air-breathing planar stack of 2 Wis achieved as a small volume of 18 cc.

• 전력전자학회논문지
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• 제15권4호
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• pp.319-326
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• 2010

LCD TV의 슬림화를 위한 전원장치는 고효율 및 고전력 밀도를 요구하고 있다. 최근 LCD TV의 LED 백라이트는 소비전력이 매우 적고 수명이 반영구적이며 밝기가 뛰어나는 동시에 기존의 CCFL 보다 적은 공간을 차지해서 두께를 혁신적으로 줄일 수 있는 장점을 지니고 있다. 그리고 본 논문에서는 LED 백라이트 구동용 고주파 평판형 트랜스포머를 이용하여 LLC 공진컨버터를 제안 적용하였고 실험 결과에 대하여 서술한다.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.70-77
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• 2024

A low energy ion irradiation system based on the deuterium arc ion source with a high perveance of 1 µP for a single extraction aperture has been successfully developed for the investigation of ion irradiation on plasma-facing components including the first mirror of plasma optical diagnostics system. Under the optimum operating condition for mirror testing, the ion source has a beam energy of 200 eV and a current density of 3.7 mA/cm². The ion source comprises a magnetic cusp-type plasma source, an extraction system, a target system with a Faraday cup, and a power supply control system to ensure stable long time operation. Operation parameters of plasma source such as pressure, filament current, and arc power with D₂ discharge gas were optimized for beam extraction by measuring plasma parameters with a Langmuir probe. The diode electrode extraction system was designed by IGUN simulation to optimize for 1 µP perveance. It was successfully demonstrated that the ion beam current of ~4 mA can be extracted through the 10 mm aperture from the developed ion source. The target system with the Faraday cup is also developed to measure the beam current. With the assistance of the power control system, ion beams are extracted while maintaining a consistent arc power for more than 10 min of continuous operation.

• 한국경제지리학회지
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• 제17권3호
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• pp.538-553
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• 2014

본 연구는 인구감소 고령화지역에서의 소매판매활동 특성을 고령화 정도와 관련시켜 고찰하는 것을 목적으로 한다. 분석결과 고령화 사회 고령사회는 유사한 주요 소매판매업종을 구성하는데 대해 초 고령사회는 다른 지역과 달리 주요 업종수도 적고, 업종구성도 다르게 나타난다. 이와 같은 특성에서 고령화가 심할수록 사업체당 종사자수와 인구 1인당 연간판매액은 적어지지만 사업체 밀도는 높게 나타나는데, 이는 농산어촌지역에 소매업사업체가 분산 입지하기 때문이고, 고령사회 초 고령사회에서의 노동생산성이 높은 소매구조의 배경은 사업체당 종사자수가 적은데서 기인한 것이다. 인구감소 고령화지역에서 높은 판매액의 구성비를 나타내는 종합소매업, 연료소매업, 음식료품 및 담배소매업에 대해 수급의 정도를 파악한 결과, 먼저 종합소매업은 고령 초 고령사회에서, 연료소매업은 대체로 판매액이 적은 고령 초 고령사회에서, 음식료품 및 담배소매업은 초 고령사회에서 '수급균형지역'으로 나타난다. 그리고 고령화의 정도가 높을수록 수급의 지역 간 격차는 작은데, 이는 지역 간의 구매력의 차이에서 기인한 것이다.

• 전력전자학회논문지
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• 제14권2호
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• pp.120-127
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• 2009

본 논문에서는 고효율 및 고전력밀도의 새로운 주파수 가변형(PFM) 직렬 부스트 캐패시터(SBC) 풀 브리지 DC/DC 컨버터를 제안한다. 제안된 회로는 기존 위상천이 풀 브리지 컨버터와 달리 스위칭 주파수에 따라 직렬 부스트 캐패시터의 전압을 가변하여 출력전압을 제어하는 방식으로, 50% 고정 시비율로 구동되므로 환류구간이 존재하지 않아 도통손실이 작다. 또한 넓은 부하 영역에 대해 영전압 스위칭 동작이 보장되며, 출력 인덕터 전류 리플도 매우 작아 출력 인덕터의 사이즈를 줄일 수 있어 대전류 사양에 매우 적합한 장점을 갖는다. 본 논문에서는 제안된 회로의 이론적 해석 및 PSIM Simulation을 수행하며, 이를 실제로 1.2kW급(12V, 100A) 서버용 컴퓨터 전원장치의 프로토 타입 제작을 통한 실험결과로부터 제안된 회로의 동작특성과 타당성을 검증한다.

• 한국수소및신에너지학회논문집
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• 제19권3호
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• pp.232-238
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• 2008

Research has been proceeded on fuel cell which is fueled by hydrogen. Polymer electrolyte membrane fuel cell (PEMFC) is promising power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, temperature dependent performance. These problems could be solved by experiment which is useful for analysis and optimization of fuel cell performance and heat management. In this paper, when hydrogen flows constantly at the stoichiometry of ${\xi}=1.6$, the performance of the fuel cell stack was increased and the voltage difference between each cells was decreased according to the increase of air stoichiometry by 2.0, 2.5, 3.0. Therefore, the control of air flow rate in the same gas channel is important to get higher performance. Purpose of this research is to expect operation temperature, flow rate, performance and mass transportation through experiment and to help actual manufacture of PEM fuel cell stack.

• Nuclear Engineering and Technology
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• 제36권4호
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• pp.357-363
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• 2004

A prototype long pulse ion source was developed, and the beam extraction experiments of the ion source were carried out at the Neutral Beam Test Stand (NBTS) of the Korea Superconducting Tokamak Advanced Research (KSTAR). The ion source consists of a magnetic bucket plasma generator, with multi-pole cusp fields, and a set of tetrode accelerators with circular apertures. Design requirements for the ion source were a 120kV/65A deuterium beam and a 300 s pulse length. Arc discharges of the plasma generator were controlled by using the emission-limited mode, in turn controlled by the applied heating voltage of the cathode filaments. Stable and efficient arc plasmas with a maximum arc power of 100 kW were produced using the constant power mode operation of an arc power supply. A maximum ion density of $8.3{\times}10^{11}\;cm^{-3}$ was obtained by using electrostatic probes, and an optimum arc efficiency of 0.46 A/kW was estimated. The accelerating and decelerating voltages were applied repeatedly, using the re-triggering mode operation of the high voltage switches during a beam pulse, when beam disruptions occurred. The decelerating voltage was always applied prior to the accelerating voltage, to suppress effectively the back-streaming electrons produced at the time of an initial beam formation, by the pre-programmed fast-switch control system. A maximum beam power of 0.9 MW (i.e. $70\;kV{\times}12.5\;A$) with hydrogen was measured for a pulse duration of 0.8 s. Optimum beam perveance, deduced from the ratio of the gradient grid current to the total beam current, was $0.7\;{\mu}perv$. Stable beams for a long pulse duration of $5{\sim}10\;s$ were tested at low accelerating voltages.

• Korean Chemical Engineering Research
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• 제53권5호
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• pp.584-589
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• 2015

잠수함 및 수중무인체계 등의 산소희박환경에서 연료전지를 통한 효과적인 전력생산을 위해서는 높은 수소저장밀도를 갖는 수소공급원이 필요하다. 디젤연료는 액체연료로서 저장 및 공급이 용이하며, 연료전지의 연료가 되는 수소의 단위질량 및 단위부피당 저장밀도가 높은 장점을 갖고 있다. 이러한 디젤연료의 장점을 기반으로 본 연구에서는 산소희박환경에서 수소생산을 위해 디젤연료의 개질반응을 이용하였으며, 산화제로 단위부피당 산소 저장밀도가 높고 액상으로 보관이 용이한 과산화수소 수용액을 기존의 산화제인 물과 산소의 대체산화제로 이용하는 방법을 제안하였다. 과산화수소 수용액의 디젤개질 산화제로써의 특성을 파악하기 위해 물, 공기 산화제와의 비교실험을 진행하였으며, 기존의 산화제와 디젤 개질반응 시 동일한 특성을 갖는 것을 실험적으로 확인하였다. 또한 상용디젤을 연료로 온도 및 과산화수소 수용액의 농도에 따른 개질성능을 평가하였으며, 49시간의 가속 열화실험을 통하여 디젤, 과산화수소 수용액을 이용한 수소생산의 가능성을 확인하였다.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.434-439
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• 2012

This paper presents a nontraditional laser power system in which an active compensated pulsed alternator (ACPA) drives a flashlamp directly without the use of capacitor groups. As a result, the volume of the laser system is decreased because of the high energy density of the ACPA. However, the difficulty in matching the output of the alternator with the laser flashlamp is a significant issue and needs to be well analyzed. In order to solve this problem, based on the theory for ACPA, the authors propose a simplified model for the system of ACPA with flashlamp load by the way of circuit simulation. The simulation results preliminarily illuminate how the performance of the ACPA laser power system is affected. Meanwhile, the simulation results can also supply a consultation for future ACPA laser power system design and control.