• 한국수소및신에너지학회논문집
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• 제34권3호
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• pp.292-296
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• 2023

Until recently, ships, automobiles, and drones using hydrogen energy are being actively researched. In addition, stations and facilities for hydrogen supply are being developed widely. Among them, a hydrogen pump is necessary for compressing it and transfer to other stations. The liquid hydrogen pump is operated at very high pressure up to 90 MPa. In our research, a reciprocating plunger pump is studied. Especially, a leakage in a liquid hydrogen pump is predicted using a finite element method. As a result, it was found that leak mass flow rates changed from 0.09 to 2.20 kg/h, when the gaps were given from 2 to 6 ㎛. Thus pump efficiencies were calculated from 99.9 to 97.9%, when the gaps changed from 2 to 6 ㎛. These results are useful for the design of the liquid hydrogen pump.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.460-462
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• 2004

The control of the data retention time is a main issue for realizing future high density dynamic random access memory. There are several leakage current mechanisms in which the stored data disappears. The mechanisms of data disappear is as follow, 1 )Junction leakage current between the junction, 2) Junction leakage current from the capacitor node contact, 3)Sub-threshold leakage current if the transfer transistor is affected by gate etch damage etc. In this paper we showed the plasma edge damage effect to find out data retention time effectiveness. First we measured the transistor characteristics of forward and reverse bias. And junction leakage characteristics are measured with/without plasma damage by HP4145. Finally, we showed the comparison TRET with etch damage, damage_cure_RTP and hydrogen_treatment. As a result, hydrogen_treatment is superior than any other method in a curing plasma etch damage side.

• 한국산학기술학회논문지
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• 제17권5호
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• pp.26-35
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• 2016

수소는 공해가 없는 청정에너지 자원으로, 이를 활용하기 위한 많은 연구가 진행되고 점차 생산 및 소비량이 늘어날 것으로 전망된다. 그러나 수소의 열화학적 특성 상 매우 높은 가연성을 가지며, 특히 밀폐공간에서 수소 가스가 누출되는 경우에 위험성이 높다. 본 연구에서는 전산유체역학 해석기법을 적용하여 밀폐된 공간 내부의 수소가스 누출 현상에 대한 수치해석 연구를 수행하였고, 실험결과와 비교하였다. 또한, 검증된 해석기법을 적용하여 누출공의 크기에 따른 가스 확산 거동에 대하여 해석하고 다양한 기법을 통해 분석하였다. 누출 시간 경과에 따른 공간 내의 가연영역을 누출공 크기 별로 확인하고, 가연영역의 체적분율을 통하여 누출공의 크기가 증가할수록 공간 내부의 가연영역은 급속히 성장함을 확인하였다. 또한 수소 가스의 누출량과 가연영역이 천장까지 성장하는 최소 소요시간 사이의 관계를 도출하였다. 특정 모니터링 지점에서 가스 몰분율 분석을 통해 가스는 형상 규모의 영향을 받지 않고 등방적 특성으로 퍼져나감을 확인하였으며, 특정 지점에서의 가스 농도는 누출구로부터 발생하는 주 유동의 효과와 밀폐공간에서의 가스 누적 효과를 모두 고려해야 함을 알 수 있었다.

• 한국가스학회지
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• 제23권6호
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• pp.74-80
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• 2019

수소를 고압으로 압축하여 사용하는 수소충전소는 안전 확보를 위해 설비간의 안전거리를 규정하고 있다. 수소 충전소에서 발생하는 사고 중 대부분의 사고는 누출사고이며, 누출 시 점화로 인해 제트화염이 생성된다. 고압의 수소 누출로 인한 가스 확산 및 제트화염의 해석은 안전거리 설정에 가장 중요한 요소이다. 본 연구에서는 고압의 환경에서 운용되는 수소충전소에서 발생할 수 있는 누출사고를 대비한 안전관리 규정 도출을 위하여 누출원 크기별 누출조건을 모사하고 위험거리 등을 파악하여 향후 안전기준 제정 시 참고자료로 활용하고자 한다.

• 한국수소및신에너지학회논문집
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• 제24권4호
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• pp.302-310
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• 2013

As an initial step to develop a liquid hydrogen pump of piston type operated under cryogenic and high pressure, leakage and piston head shape for the piston pump were discussed with temperature and pressure. As the results, the leakage depended on correlation among density, viscosity, clearance area by the low temperature. In order to reduce the leakage, it was found that the air-tightness can be improved by minimizing contact surface between piston and cylinder, and also increasing pressure in-cylinder can reduce piston clearance. Among the proposed piston shapes, D type piston shape had the most air-tightness. D type piston had smaller contact surface than other piston shape and easier expansion of cup shape by pressure. The leakage of D type piston shape was found about 7%, compared with A type piston shape. But it was required that analyze about vapor lock by friction and wear resistance.

• 자동차안전학회지
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• 제15권1호
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• pp.27-34
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• 2023

The registration rate of eco-friendly vehicles, such as hydrogen vehicles, is increasing rapidly, however, few first responders have experienced related accidents. Accident scenarios at hydrogen refueling stations and hydrogen vehicles on a road were investigated, and the relative importance of each scenario was analyzed using AHP analysis. Leakage, jet flame, and explosion that occurred inside and outside the hydrogen refueling station were reviewed, and the hydrogen gas explosion in the compartment showed the highest importance value. In case of the hydrogen vehicle, traffic accident statistics and actual accidents were used. It was analyzed that the hydrogen vessel explosion on the road due to the failure of TPRD and the leakage in the underground parking area were difficult to respond. The developed accident scenarios are expected to be used for first responder training.

• 해양환경안전학회지
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• 제30권2호
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• pp.165-175
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• 2024

수소는 기후변화 위기에 대응하기 위한 에너지원 중 하나로 주목받고 있다. 그러나, 수소는 밀폐된 공간에 누출되면 천장으로 상승하여 축적되고, 점화원과 만나면 화재나 폭발의 위험이 있다. 특히, 수소를 운송하거나 연료로 사용하는 선박은 여러 밀폐된 공간으로 구성되어 있기 때문에 수소를 안전하게 사용하기 위해서는 공간 내에서의 확산 특성을 파악해야 한다. 본 연구는 선박 내 밀폐된 공간에서 수소와 유사한 특성을 가진 헬륨의 누출방향에 따른 확산 특성을 실험적으로 파악하고, CFD 시뮬레이션을 통해 환기횟수가 25, 30, 35, 40, 45ACH로 증가함에 따라 누출방향에 따른 산소농도 변화를 파악하는 것이 목적이다. 연구 결과, 산소농도감소율은 -z 방향의 누출이 2%, +x와 +z 방향의 누출이 1%였으며, 환기소요시간은 -z 방향 누출이 15분 30초, +x 방향 누출이 7분, +z 방향 누출이 9분으로 누출방향에 따라 산소농도와 환기소요시간에 차이가 있음을 보여준다. 또한, 실험공간에서 환기횟수 35ACH 이상부터는 모든 누출 방향에서의 산소농도감소율과 환기소요시간에 유의미한 차이가 없었다. 따라서, 환기횟수를 증가하여도 산소농도와 환기소요시간이 개선되지 않았기 때문에 본 실험환경에서의 적정 환기횟수는 35ACH임을 알 수 있었다.

• 한국수소및신에너지학회논문집
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• 제17권3호
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• pp.272-278
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• 2006

This study is quantitatively assessing of safety about dispenser of hydrogen station because it is hydrogen energy to efficient safety use. The large leakage of hydrogen gas is the most important accident among others occurrence possibility in hydrogen station. It had written FT by top event and calculated unavailability, m-cutsets, leakage frequency, etc with FTA after each base event collect reliability data by reliability data handbook, THERP-HRA and estimation of the engineering.

• 한국기계가공학회지
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• 제19권11호
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• pp.8-15
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• 2020

The government has announced its Hydrogen Economy Roadmap to strengthen global competitiveness on the hydrogen economy by focusing on hydrogen fuel cell electric vehicles and fuel cells. In this regard, the interest on the economics and safety of the infrastructure of hydrogen stations has also increased. In this study, a test bed similar to an actual hydrogen charging facility was built, and a prototype of a piston-type compressor was modeled. In this model, the piston was hydraulically compressed to progressively test leakage, leakage rate, and durability and to check for any malfunction. Moreover, the leakage rate, cylinder leak performance, and compressor operation durability were evaluated for safety; it was confirmed that there were no abnormalities. Nevertheless, an investigation of the long-term use and operating pressure of the compressor is necessary to verify the safety of developing a100-MPa domestic compressor in the future.

• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.205-211
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• 2023

Hydrogen gas is light and diffuses very quickly. Therefore, when a leakage accident occurs, the damage is great, so a technology that can quickly measure the leakage in the air at a long distance is needed. In order to develop hydrogen gas leaked in the atmosphere in a non-contact manner, an experiment was performed to measure hydrogen gas using a lidar technology using the Raman effect. Hydrogen Raman signals were detected using a UV LED light source, which is a Raman light source, and a spectrometer in the ultraviolet region including an optical filter in the 400-430 nm band. To develop this, a Raman lidar optical structure was designed to measure the hydrogen Raman signal at a certain distance, and the hydrogen Raman spectrum was confirmed using a standard gas to evaluate the performance of this optical structure. The linearity was found to be 0.99 using hydrogen standard gas (10, 50, 100, 500, 1,000 ppm). Accordingly, a Raman lidar capable of measuring hydrogen gas rapidly diffusing in the air in an open state was developed to improve the limitations of existing hydrogen sensors.