• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.313-331
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• 2022

Natural or native abiotic molecular hydrogen (H₂) is a major component in natural gas, however yet its importance in the global energy sector's usage as clean and renewable energy is underestimated. Here we review the occurrence and geological settings of native hydrogen to demonstrate the much widesprease H₂ occurrence in nature by comparison with previous estimations. Three main types of source rocks have been identified: (1) ultramafic rocks; (2) cratons comprising iron (Fe²⁺)-rich rocks; and (3) uranium-rich rocks. The rocks are closely associated with Precambrian crystalline basement and serpentinized ultramafic rocks from ophiolite and peridotite either at mid-ocean ridges or within continental margin(Zgonnik, 2020). Inorganic geological processes producing H₂ in the source rocks include (a) the reduction of water during the oxidation of Fe²⁺ in minerals (e.g., olivine), (b) water splitting due to radioactive decay, (c) degassing of magma at low pressure, and (d) the reaction of water with surface radicals during mechanical breaking (e.g., fault) of silicate rocks. Native hydrogen are found as a free gas (51%), fluid inclusions in various rock types (29%), and dissolved gas in underground water (20%) (Zgonnik, 2020). Although research on H₂ has not yet been carried out in Korea, the potential H₂ reservoirs in the Gyeongsang Basin are highly probable based on geological and geochemical characteristics including occurrence of ultramafic rocks, inter-bedded basaltic layers and iron-copper deposits within thick sedimentary basin and igneous activities at an active continental margin during the Permian-Paleogene. The native hydrogen is expected to be clean and renewable energy source in the near future. Therefore it is clear that the origin and exploration of the native hydrogen, not yet been revealed by an integrated studies of rock-fluid interaction studies, are a field of special interest, regardless of the presence of economic native hydrogen reservoirs in Korea.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.397-400
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• 2008

Traditional propellants which have a hypergolic characteristic have a high performance but also have disadvantages of toxicity and complex handling requirement. In order to replace these propellants, one of the alternatives is hydrogen peroxide which generates high temperature oxygen and water vapor after catalytic reaction. In this paper, autoignition characteristics of kerosene by decomposed hydrogen peroxide were investigated to perform fundamental research for designing a thruster using hydrogen peroxide and kerosene propellants. Contraction ratio, whether flame holder exists or not, and feeding pressure of propellants were selected as variables. From the experiments for different mixture ratio, we confirmed the ignition stability is strongly affected by a feeding pressure of propellants.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.674-683
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• 2022

In this study, we examined the case of Fukushima Hydrogen Research Field (FH2R) Namie hydrogen town. We found that the case has three aspects of socio-technical experiment: a living-scale test-bed of hydrogen technologies, activities for enhancing social acceptability, and a designed module for policy transfer to diffuse. This study aims to provide a benchmark for planning a green hydrogen city in near future.

• Fire Science and Engineering
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• v.22 no.3
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• pp.234-238
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• 2008

Autoignition suppression of hydrogen/air premixed mixtures by $CF_3CHFCF_3(HFP)$ was investigated computationally. Numerical simulation was performed in isobaric and homogeneous system to evaluate the induction times. The detailed chemistry of 93 species and 817 reaction mechanism was introduced for hydrogen/air/HFP mixtures. The result of pure hydrogen/air mixture show that the resulting value of induction time depends relatively weakly on the definition used event though there are various criteria for defining the induction time such as the inflection of temperature, OH and $O_2$ concentrations generally. Also, the autoignition temperature of $H_2/air$ mixture is estimated to about 850K, which is corresponds to the literature value. In the case of HFP addition in $H_2/air$ mixture, the results shows that there are several inflection points of radical concentration, and hence it might be to use the temperature for defining ignition delay. When HFP is added to stoichiometric $H_2/air$ mixture, the effect of ignition delay is outstanding above 10% HFP concentration. As HFP concentration increases, both dilution and chemical effects contribute to delay the ignition. Also, the chemical effect on the ignition delay is more considerable with the higher HFP concentration.

• Membrane Journal
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• v.32 no.5
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• pp.275-282
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• 2022

In contemporary days, hydrogen-based energies including batteries are renowned to be effective. And its effectiveness comes from the fact that it possesses high efficiency as an energy carrier. Eco-friendly and high purity of hydrogens comes out from water electrolysis. And among different types of electrolysis, proton exchange membrane (PEM) water electrolysis is considered the most renewable, cheap, and eco-friendly. It produces oxygen and hydrogens which are feasible in using as energies. Since it has such a number of benefits, increased research is going on in PEM electrolysis. Nafion is widely used as PEM, but high cost and various other disadvantages leads to the exploration of alternative materials. This review is broadly classified into Nafion and non Nafion based PEM for water electrolysis.

• Journal of Hydrogen and New Energy
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• v.34 no.3
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• pp.274-282
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• 2023

This study conducted direct numerical simulations of the natural convection phenomena of gaseous hydrogen in a physical storage container containing four circular cylinders. Rayleigh numbers (Ra) in the range of 10⁴≤Ra≤10⁶ and a Prandtl number (Pr)=0.69 (gaseous hydrogen) were considered. The main parameter is a horizontal distance of four circular cylinders and the values of ε_h=0.1, 0.2, 0.3, 0.4, and 0.5 are considered. The flow and thermal structures and corresponding heat transfer characteristics are investigated with respect to the transition of the flow regime. The time- and surface-averaged Nusselt number on the cylinder surface and the wall of physical storage container increased by about 57% and 69% according to the Ra and ε_h, respectively. Thus, the horizontal distance has an influence on the heat transfer characteristics on natural convection of gaseous hydrogen.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.1-6
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• 2008

For the safety design and operation of many gas process, it is necessary to know certain explosion limit, flash point, autoignition temperature (AIT) and minimum oxygen concentration of handling substances. Also it is necessary to know explosion limit at high temperature and pressure. In this study for the safe handling of hydrogen, explosion limit and AIT of combustion properties for hydrogen were investigated. By using the literatures data, the lower and upper explosion limits of hydrogen recommended 4.0 vol% and 77.0 vol%. Also the AIT of hydrogen with ignition sources recommended $400^{\circ}C$ at the electrically heated crucible furnace (the whole surface heating) and recommended $640^{\circ}C$ at the local hot surface. The new equations for predicting the temperature and the pressure dependence of the explosion limits of hydrogen are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• The Journal of Natural Sciences
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• v.4
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• pp.29-58
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• 1991

Ethanol은 섭취량에 따라 간 대사에 여러가지 영향을 미치는 것으로 알려져 있다. 과량의 ethanol 섭취가 유해한 것은 ethanol 그 자체보다는 산화과정에서 생성된 acetaldehyde와 과량의 수소(NADH)에 기인한다. 과량의 NADH는 간 세포의 화학적 평형을 저해하고 대사이상을 초래한다. 본 연구에서는 in vitro 뿐만 아니라 in vivo에서 alcohol dehydrogenase(ADH), aldehyde dehydroge-nase(ALDH), microsomal ethanol oxidizing system(MEOS)에 미치는 인삼 사포닌의 영향을 조사하고, 간에서의 수소 평형, 간에서의 $[1^(-14)C]$-ethanol의 분포, ethanol의 acetaldehyde와 lipid로의 전환 등을 관찰하였다. 인삼 사포닌은 상기 효소외에도 ethanol 대상에 관련된 다른 효소들의 활성을 증가시키는 것으로 관찰되었으며 이는 동물 체내로부터 acetaldehyde와 과량의 수소를 신속히 제거하는 것으로 사료된다.

• The Science & Technology
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• v.32 no.2 s.357
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• pp.32-34
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• 1999

화학은 처음 중성원자로서의 수소가 생겨난 이후 옥텟규칙에 따라 최초의 분자인 수소분자가 우주공간에서 만들어지면서 분자과학으로서의 막을 올리게 된 것이다. 지금까지 화학은 원자들을 꿰어서 약 1천8백만가지의 화합물질을 만들어 냈다. 화학자들은 또 자연에 의존하는 화합물중에서 유용한 것을 골라내기도 하지만 전혀 새롭고 유용한 화합물을 설계하고 만들어왔는데 이처럼 다양하고 신비로운 화학의 세계를 들여다 본다.

• Korean Journal of Materials Research
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• v.6 no.7
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• pp.661-670
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• 1996

리모트 수소 플라즈마를 이용하여 실리콘 웨이퍼 표면 위에 있는 금속불순물의 제거 및 제거기구에 관하여 조사하였다. 실리콘의 표면과 내부분석을 위하여 TXRF(total reflection x-ray fluorescence)와 SPV(surface photovoltage), AFM(atomic force microscope)을 사용하였다. TXRF 분석결과 리모트 수소 플라즈마가 금속오염물질 제거에 상당한 효과가 있는 것으로 나타났다. TXRF분석결과 리모트 수소 플라즈마가 금속오염물질 제거에 상당한 효과가 있는 것으로 나타났다. 리모트 수소플라트마 처리 후 금속오염은 금속원소의 종류에 따라 1010atoms/$\textrm{cm}^2$-1011atoms/$\textrm{cm}^2$수준이었다. SPV분석결과를 보면 수소 플라즈마 처리에 의해 minority carrier 수명이 전반적으로 증가하였다. AFM 분석을 통하여 수소 플라즈마 처리가 표면 손상을 일으키지 않으며 표면의 거칠기에 나쁜 영향을 미치지 않음을 알 수 있었다. 또한 본 실험에서 나타난 결과들을 종합해 볼 때 금속오염물의 제거기구는 자연산화막 혹은 수소로 passivate된 실리콘 웨이퍼 표면을 수소 플라즈마에서 발생된 수소원자가 실리콘표면을 약하게 에칭할 때 떨어져 나가는 'lift-off'가 유력한 것으로 판단된다.