• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.53-65
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• 2021

While the hydrogen refueling station is rapidly expanded and installed, the safety inspection of the hydrogen pressure vessel in the station should be very important. Of these, according to ASME, hydrogen embrittlement tests must be performed for hydrogen vessel that store hydrogen above a certain pressure. The main test method for hydrogen embrittlement inspection is to carry out fracture tests and fatigue fracture tests in a high pressure hydrogen atmosphere, which allows the durability limit of the pressure vessel to be measured and the endurable limit to be determined in the hydrogen atmosphere. In detail, the critical crack depth can be calculated by the stress intensity factor(K), and the service life can be determined by da/dN (fatigue growth rate). API579-1/ ASME FFS-1 part 9 exemplifies the calculation method according to the mode of crack-like flaws, but for various shapes such as plates and cylinders, there are about 55 modes according to the shape and location of the crack. Due to the fairly complex formula, it is not easily accessible. In this study, we will show you how to calculate fracture mechanics numerically via Excel and VBA. In addition, this was applied to analyze the effects of the thickness and inner diameter of the pressure vessel on the service life.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.42-47
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• 2000

The surface structure and the crystalline features in the near surface region have been investigated for CZ(Czochralski) grown Si wafers. Si wafers were annealed by RTA (Rapid Thermal Annealing) method in H$_2$ambient after mirror polished process. The densities of COPs (Crystal Originated Particles) after RTA process were remarkably decreased at the surface and in the region of 5um depth from the surface as well. terrace type surface structure which was formed by etching and re-arrangement of Si atoms during $H_2$annealing process also has been observed.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.3
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• pp.219-226
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• 2014

In HI decomposition, $Pt/Al_2O_3$ has been studied by several researchers. However, after HI decomposition, it could be seen that metal dispersion of $Pt/Al_2O_3$ was greatly decreased. This reason was expected of platinum loss and sintering, which platinum was aggregated. Also, this decrease of metal dispersion caused catalytic deactivation. This study was conducted to find the condition to minimize platinum sintering and loss. In particular, heat treatment atmosphere and temperature were examined to improve the activity of HI decomposition reaction. First of all, although $Pt/Al_2O_3$ treated in hydrogen atmosphere had low platinum dispersion between 13 and 18%, it was shown to suitable platinum form that played an important role in improving HI decomposition reaction. Oxygen in the air atmosphere made $Pt/Al_2O_3$ have high platinum dispersion even 61.52% at $500^{\circ}C$. Therefore, in order to get high platinum dispersion and suitable platinum form in HI decomposition reaction, air heat treatment at $500^{\circ}C$ was needed to add before hydrogen heat treatment. In case of 5A3H, it had 51.13% platinum dispersion and improved HI decomposition reaction activity. Also, after HI decomposition reaction it had considerable platinum dispersion of 23.89%.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.2
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• pp.238-243
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• 2012

The purpose of this study is to search the temperature-rise time conditions for adequate reforming temperature region of hydrogen generation system. And we measured theexhaust gas at the exit of that system in order to know the combustion state of hydrogen generation system's combustor. We found the optimum condition of heat supply and temperature-rise time at well burned state. And the results were nearly same when the reactants were entered to each reactors. We will further consider the effects of temperature change near the exothermic reactors and find out hydrogen yield through reforming experiment.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.25-30
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• 2005

수소 분위기에서 10wt.%MnO와 기계적인 분쇄(반응성 기계적 분쇄)에 의해 Mg의 수소 저장 성질을 향상시켰다. 회전 속도는 250 rpm, 밀링시간은 2 h, 그리고 시료 대 볼 중량비는 1/45이었다. 준비한 Mg-10wt.%MnO 시료는 활성화를 위한 수소화물 형성 분해 싸이클링이 필요없었으며, 첫 번째 싸이클 593k 12 bar $H_2$에서, 10분 동안에 3.12wt.%, 60분 동안에 3.95wt.%의 수소를 흡수하였다. 또한 Mg-10wt.%MnO는 593k 0.8 bar $H_2$에서 60분 동안에 2.12wt.%의 수소를 방출하였다. MnO와 Mg의 방응성 분쇄는, 핵생성을 용이케하고 (Mg 입자의 표면에 결함 형성과 첨가물에 의해), Mg 입자의 표면에 crack을 만들어 Mg의 입자 크기를 줄여 그 결과 수소 원자의 확산 거리를 작게 함으로써 수소 흡수 방출 속도를 증가시킨다. 수소화물 형성 분해 싸이클링은 Mg 입자의 표면에 crack을 만들고 Mg의 입자 크기를 줄여 수소 흡수 방출 속도를 증가시킨다.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1043-1044
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2010.06a
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• pp.25-26
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• 2010

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2005.11a
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• pp.170-170
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• 2005

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.302-309
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• 2017

If a hydrogen explosion occurs in a containment building, its multiplex defense wall may be destroyed and a large amount of radioactive material may be released. The hydrogen occurred interacting with melting fuel rods must be effectively controlled and removed. however, the countermeasures for reducing explosion risk are difficult to carry out, due owing to the various variety of accident scenarios causes and the irregularity of hydrogen distribution and behavior. In this study, We examine the guide structures while considering the ambient flows, in order to improve the efficiency of PAR the widely used Passive Autocatalytic Recombiner(PAR). We simulate the fluid behavior and the hydrogen reduction rate were simulated when a guide is attached to the two-step catalyst PAR. For an upward flow, the consisting of a height of 150mm, a gap of 0mm, and a performs $60^{\circ}$ showed the best. In contrast, for a sideways flow, a consisting of the height of 150mm, a gap of 100mm, and a performs $60^{\circ}$ showed the best in the case of side ward flow. for a downward flow, a consisting of the height of 50mm and a directly attached guide produce the best in the case of down ward flow results.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.884-888
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• 1998

Effects of heating time under high temperature on the thermal and mechanical properties of neutron shielding materials based on modified (KNS-102), hydrogenated(KNS-106) bisphenol-A type epoxy resin and phenol-novolac(KNS-611) type epoxy resin for radioactive material shipping casks have been investigated. At early stages, the initial decomposition temperatures of the shielding materials of KNS-102, KNS-106 and KNS-611 increased with the heating time under high temperature, but it was rarely affected by the heating time in the later stages. In addition, the thermal conductivities of KNS-102 and KNS-106 decreased with heating time, but that of KNS-611 increased with the heating time. On the contrary, the thermal expansion coefficients of neutron shielding materials decreased with increase of heating time. At the high temperature, the tensile strength and flexural strength of the shielding materials of KNS-102 and KNS-611 increased with heating time, but those of KNS-106 decreased with increase of heating time. And the heating time under high temperature on the neutron shielding materials did not show measurable loss of weight and hydrogen content.