• 대한화학회지
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• 제54권4호
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• pp.437-442
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• 2010

수용액 속에서 $NaHSO_4$, TBAB (phase transfer catalyst), ionic liquid (IL) (1-butyl-3-methyl imidazolium hydrogen sulphate [bmim]$HSO_4$)를 사용하여, formalin, ${\beta}$-naphthol, aromatic amines을 반응시켜서 대응하는 2,3-dihydro-2-phenyl-1Hnaphtho-[1,2-e] [1,3] oxazine 유도체를 합성할 수 있는 보다 친환경적이고, 수율이 좋고, 크로마토그래피 분리 방법을 사용하지 않는 합성 방법을 개발하였다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.601-604
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• 2010

본 연구는 과산화수소와 케로신을 추진제로 하는 액체로켓엔진에 막냉각 링을 장착하여 막냉각 효과에 관한 연구를 수행하였다. 막냉각제의 유량 및 냉각장치 형상에 따른 열유속을 계산하기 위하여 축방향으로 열전대를 장착하여 온도를 측정하였다. 냉각제 유량은 총 추진제 유량의 0~20%의 유량으로 선정하여 실험을 수행하였다.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.119-127
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• 2019

Reliable $H_2$ supply is necessary for entering a $H_2$ society. Among the various $H_2$ storage and transportation methods, liquid organic $H_2$ carrier (LOHC) is in the spotlight because of a lot of advantages compared to conventional one such as compressed $H_2$ and liquefied $H_2$. Therefore, we performed preliminary economic analysis of $H_2$ supply cost using LOHC for a $H_2$ production capacity of $300Nm^3\;h^{-1}$ employing itemized cost estimation and sensitivity analysis to evaluate economic viability of this technology in Korea.

• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.27-38
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• 2022

Urban air mobility (UAM) has recently attracted lots of attention as a solution to urban centralization and global warming. Electric vertical take-off and landing (eVTOL) is a concept that emerges as one of the promising and clean technologies for UAM. There are two difficult challenges for eVTOL aircraft to solve. One is how to improve the weight efficiency of aircraft, and the other is how to complete long-range missions for UAM's flight scenarios. To approach these challenges, we propose a consolidated concept design of battery-fuel cell hybrid tiltrotor aircraft with a liquid hydrogen (LH₂) fuel tank. The efficiency of a battery-fuel cell hybrid powertrain system on the designed eVTOL aircraft is compared to that of a battery-only powertrain system. This paper shows how much payload can increase and the flight scenario can be improved by hybridizing the battery and fuel cell and presenting a detailed concept of a cryogenic storage tank for LH₂.

• 한국가시화정보학회지
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• 제22권2호
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• pp.11-19
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• 2024

We performed numerical simulations on a C-type liquid hydrogen (LH2) storage tank for commercial vehicles to reduce evaporation rates by manipulating vortical structures. Owing to external heat, natural convection occurs inside the tank, leading to the enhanced evaporation of LH2. We observed that the regions of high magnitude vorticity correlate with those of high evaporation rates. Specifically, vortical structures in the side section area show higher vorticity magnitude and evaporation rates compared to those in the midsection area. To suppress these vortical motions, we installed an array of ribs at intervals corresponding to the mean diameter of the vortical structures. As a result, the area occupied by vortical structures in the side section area decreased, leading to a reduction in evaporation speed by approximately 2.3 times. This study elucidates the internal evaporation mechanism in storage tanks from the perspective of flow structures and potentially contributes to minimizing the boil-off rate in cryogenic storage tanks.

• 한국수소및신에너지학회논문집
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• 제16권3호
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• pp.290-295
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• 2005

For the application of fuel cell, the content and concentration of impurities in hydrogen stream must be classified. The purpose of this study is to provide analysis tool for the determination of impurities in hydrogen with ultra high purity. To produce UHT hydrogen, we purified hydrogen gas by both getter-based catridge and liquid-nitrogen soaked catridge. We compare two methods and propose new method to know about what is in hydrogen stream.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.175-178
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• 2011

본 논문에서는 자세제어용 추력기에 사용되는 단일액체추진제의 성능특성 및 활용현황을 조사한다. 과산화수소는 단일추진제로서 1960년대 중반까지 활발히 사용되었으나, 비추력 성능과 저장성이 탁월한 하이드라진으로 급속히 대체되었다. 하이드라진은 양호한 성능특성을 배경으로 인공위성, 행성간 탐사선, 우주발사체 등의 단일추진제로서 가장 많이 사용되고 있다.

• 한국수소및신에너지학회논문집
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• 제29권6호
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• 한국추진공학회지
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• 제14권4호
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• pp.46-58
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• 2010

최근 들어 새로운 차세대 우주발사체의 추진기관의 개발 방향에서 친환경성과 저비용성이 주요 관심사이며, 과산화수소와 액체메탄은 이러한 추진제로 대표적인 관심을 받고 있다. 과산화수소는 로켓 개발 초기에 널리 사용되었으나, 냉전시대에 성능을 최우선시함에 따라 사용이 현격히 감소해오다가 1990년대 이후 안정성의 향상과 더불어 다시 재조명 받기 시작하였다. 액체메탄은 실제 발사체의 추진기관으로 사용되지는 않았지만, 액화천연가스(LNG)로 사용할 수 있기 때문에 친환경/저비용 추진제로 지속적으로 관심을 받아왔으며 최근에는 달/화성 탐사와 관련하여 지속적인 연구가 수행되고 있다. 이러한 대표적인 친환경 추진제에 대한 활용 역사와 최근 연구 동향을 고찰하여, 향후 국내에서 소요될 각종 임무 조건을 만족하는 엔진의 연구 개발 방향 설정에 도움이 될 것으로 예상된다.

• 한국수소및신에너지학회논문집
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• 제21권6호
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• pp.513-518
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• 2010

In the present work the second-order perturbation solutions of the simple physical model for liquid pool spreading is obtained for the case of instantaneous spill. To generalize the solution governing equations are non-dimensionalized, and two dimensionless parameters, dimensionless evaporation rate and aspect ratio of the initial pool, are identified to control the governing equations. The dimensional governing equations have three parameters. The second-order solution improves fairly the first-order solution for the pool volume.