• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.11
• /
• pp.1377-1382
• /
• 2011

Recently, alternative and novel energy resources have been developed for use in the future because of the current environmental problems and exhaustion of fossil energy resources. Hydrogen energy has many merits, such as its environmental friendliness, easy storage, and easy production, but it also has disadvantages, in that it is highly combustible and explosive. In this study, a test procedure using a simple SP test under highly pressurized hydrogen gas conditions was established. In order to evaluate its applicability, SP tests were carried out using a stainless steel (SUS316L) sample under atmospheric, pressurized helium, and pressurized hydrogen gas conditions. The results under the pressurized hydrogen gas condition showed fissuring and produced a reduction of the elongation in the plastic instability region due to hydrogen embrittlement, showing the effectiveness of the current in-situ SP test.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2015.10a
• /
• pp.521-522
• /
• 2015

• Journal of the Korean Institute of Gas
• /
• v.25 no.6
• /
• pp.53-65
• /
• 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 Institute of Gas
• /
• v.15 no.2
• /
• pp.9-14
• /
• 2011

A set of test was conducted on a SA-372 steel for CNG storage tank to study the effect of hydrogen embrittlement. Tensile tests were carried out several conditions such as CNG, HCNG and H2 gas environment including air and Ar under the 35 MPa. Also, the test speed was set at 4*10^-4/s and 4*10^-5/s respectively. To maintain the high pressure for environmental gas during test process, we chose MTS which was installed autoclave. Test results showed that tensile stress, elongation rate and cross sectional contraction under Ar and CNG charging condition were similar to that of reference of air. And there was little bit change with test speed variations. However, hydrogen added conditions such as HCNG and H2 were revealed noticeable change in elongation rate and cross sectional contraction. Tensile stress was still uniform for all conditions. From the results, the effect of hydrogen embrittlement was confirmed on the hydrogen enriched conditions. Also its effect was showed more strong with much hydrogen concentration and slower test speed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.923-927
• /
• 2017

Metal exposed to high temperature/high pressure/oxidizer-rich environment may cause rapid oxidation(ignition and combustion). Therefore, this study was performed for the selection of metal appropriate for high temperature/high pressure/oxidizer-rich environment. In order to make the high temperature, high pressure and oxidizer-rich environment, the test facility utilizing the catalytic reaction of hydrogen peroxide was constructed and the metal oxidation and ignition of the STS series metals were evaluated. The result showed that the change of the selected material (discoloration) and the surface roughness were observed, but the change in the weight and thickness of the specimen was not significant.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2011.05a
• /
• pp.77-78
• /
• 2011

저비용, 고효율, 안정적 수급이 가능한 전력 에너지원이 요구되면서 석탄이 새로운 에너지원으로 급부상하게 됨에 따라 차세대 친환경 석탄화력 발전기술인 IGCC (Integrated Gasification Combined Cycle) 발전 시스템 의 개발이 필요하게 되었다. 석탄가스화 공정(IGCC: integrated coal gasification combined cycle)은 석탄을 가스화한 후 이를 이용하여 복합발전소를 운전하는 발전기술로서 석탄을 고온, 고압아래에서 수소와 일산화탄소를 주성분으로 한 합성가스로 전환한 뒤 합성가스 중에 포함 된 분진과 황 화합물 등 유해물질을 제거하고 천연가스와 유사한 수준으로 정제하여 전기를 생산하는 친환경 발전 기술이다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.29-30
• /
• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide ($SiO_2$) under both Negative-bias Temperature Instability(NBTI) and Hot-carrier-induced(HCI) stresses using P and NMOSFETs that are annealed with hydrogen or deuterium gas at high-pressure (1~5 atm.). Statistical parameter variations depend on the stress conditions. We suggest that deuterium bonds in $SiO_2$ film is effective in suppressing the generation of traps related to the energetic hot electrons.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.11
• /
• pp.7-13
• /
• 2004

Experimental results are presented for the degradation of 3 nm-thick gate oxide under -2.5V $\leq$ V$_{g}$ $\leq$-4.0V stress and 10$0^{\circ}C$ conditions using P and NMOSFETs that are annealed with hydrogen or deuterium gas at high-pressure (5 atm). The degradation mechanisms are highly dependent on stress conditions. For low gate voltage, hole-trapping is found to dominate the reliability of gate oxide both in P and NMOSFETs. With increasing gate voltage to V$_{g}$ =-4.0V, the degradation becomes dominated by electron-trapping in NMOSFETs, however, the generation rate of "hot" hole was very low, because most of tunneling electrons experienced the phonon scattering before impact ionization at the Si interface. Statistical parameter variations as well as the gate leakage current depend on and are improved by high-pressure deuterium annealing, compared to corresponding hydrogen annealing. We therefore suggest that deuterium is effective in suppressing the generation of traps within the gate oxide. Our results therefore prove that hydrogen related processes are at the origin of the investigated oxide degradation.gradation.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.8
• /
• pp.829-833
• /
• 2012

SNG (synthetic natural gas or substitute natural gas) could contribute greatly toward energy security. In addition, HCNG (or $H_2CNG$) is expected to be used as a fuel gas for internal combustion engines and home appliances because it has extremely low emissions and high thermal efficiency. However, the hydrogen contained in SNG or HCNG can deteriorate the mechanical properties of the materials used in existing natural gas infrastructure. Therefore, it is necessary to investigate the effect of hydrogen on the mechanical properties of such materials so that SNG or HCNG can be transported and distributed safely and reliably. In this study, the effect of highly pressurized hydrogen gas on the tensile properties of a low-alloy steel used for manufacturing CNG storage vessels was investigated using the so-called hollow tensile specimen technique.

• Clean Technology
• /
• v.16 no.1
• /
• pp.19-25
• /
• 2010

In this work, the conversion of crystalline cellulose into polyols in the presence of hydrogen was examined over noble metal (Pt, Ru, Ir, Rh, and Pd) catalysts supported on activated carbon. For comparison, Pt/${\gamma}-Al_2O_3$ and Pt/H-mordenite were also investigated. Several techniques: $N_2$ physisorption, X-ray diffraction(XRD), inductively-coupled plasma-atomic emission spectroscopy (ICP-AES), temperature-programmed reduction with $H_2$ ($H_2$-TPR) and CO chemisorption were employed to characterize the catalysts. The cellulose conversion was not strongly dependent on the types of the catalyst used. Pt/AC showed the highest yields to polyols among activated carbon-supported noble metal catalysts, viz. Pt/AC, Ru/AC, Ir/AC, Rh/AC and Pd/AC.