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CNG 저장용기용 저합금강의 인장 특성에 미치는 고압 수소가스의 영향
이해무(H. M. Lee),정인현(I. H. Jeong),박종서(J. S. Park),남승훈(S. H. Nahm),한정옥(J. O. Han),이영철(Y. C. Lee) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.8
대체천연가스(SNG)는 에너지 안보 차원에서 에너지 수급 안정화 방안의 하나로 많은 관심을 받고 있다. 또한 HCNG (또는 H₂CNG)는 배기가스 내의 유해 성분을 현저히 줄이고 열효율도 높일 수 있어서 내연기관이나 가정용 연료로 사용될 것으로 기대되고 있다. 그러나 SNG나 HCNG에 포함되어 있는 수소는 재료에 침투하여 그 재료의 역학적 특성을 크게 저하시키는 것으로 알려져 있다. 따라서 SNG나 HCNG를 안전하고 효율적으로 수송ㆍ공급하려면 이를 위해 운용되는 인프라의 안전성과 신뢰성 확보가 선결되어야 한다. 본 연구에서는 중공 시험편을 이용한 인장시험법을 통하여 CNG 저장용기용 저합금강이 나타내는 고압 수소 분위기에서의 인장 특성 변화에 대하여 조사하였다. SNG (synthetic natural gas or substitute natural gas) could contribute greatly toward energy security. In addition, HCNG (or H₂CNG) 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.
CNG 저장용기용 저합금강의 인장 특성에 미치는 고압 수소가스의 영향
이해무(H. M. Lee),정인현(I. H. Jeong),박종서(J. S. Park),남승훈(S. H. Nahm),한정옥(J. O. Han),이영철(Y. C. Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Natural gas that can be produced from coal or biomass is known as “synthetic natural gas” or “substitute natural gas” (SNG). SNG could be a major driver for energy security. SNG production could diversify energy options and reduce natural gas imports. Also, HCNG (or H₂CNG), a mixture of CNG(compressed natural gas) and 4-9 percent hydrogen by energy, is expected to be used as a fuel gas for internal combustion engines and home appliances due to extremely low emissions and increases in thermal efficiency. However, mechanical properties can be deteriorated by hydrogen contained in SNG or HCNG. It is necessary, therefore, to investigate the effect of hydrogen on the mechanical properties of materials used for the existing natural gas infrastructure so that SNG or HCNG can be transported and distributed safely and reliably. In this study, the effect of highly pressurized hydrogen gas on tensile properties of a low alloy steel used for CNG storage vessels was investigated using so-called hollow tensile specimen technique.
이해무,윤기봉,남승훈,소철호 ( H . M . Lee,K . B . Yoon,S . H . Nahm,C . H . Soh ) 한국열처리공학회 1994 熱處理工學會誌 Vol.7 No.3
As Cr-Mo-V steels have excellent mechanical and creep properties at elevated temperatures, they are extensively used in power plants. However, the steam turbine components are supposed to have suffered material degradation during long-term service at elevated tenperatures. Many efforts have been made to assess the safety and residual life of these components by means of non-destructive methods such as plastic replication, hardness and electric resistance techniques. Recently, a parameter correlating hardness changes during long-term heating to those during creep was introduced and it was named `G parameter`. The electric resistivity as well as hardness are affected by damage accumulation, but there have been no efforts to correlate G parameter to resistivity changes. In this study, relationship between G parameter and changes in electric resistivity was investigated using artificially aged Cr-Mo-V steel. It is well understood that G parameter can be applied to electric resistance techmique.
허용학(Y.-H Huh),이해무(H.M. Lee),김동진(D.J. Kim),박종서(J.S. Park) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Estimation of measurement uncertainty of tensile properties of material was carried out. Sources of uncertainty affecting the measurement of tensile properties were classified and analyzed. The model for evaluation of the uncertainty was suggested and the measurement uncertainty of tensile properties was evaluated from the experimental data of SUS316LN obtained according to ISO 6892. The model was derived from the mathematical relation of the measurands, such as elastic modulus, yield strength and tensile strength, and measuring quantities by calculating each sensitivity coefficient of the quantities. Based on these models, the measurement uncertainty of the elastic modulus, yield and tensile strengths were evaluated.
허용학(Y.-H Huh),김동진(D.J. Kim),이해무(H.M. Lee),홍성구(S.G. Hong),박준협(J.H. Park) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
Fatigue limit of the copper film coated by Sn was estimated by using Goodman diagram and Gerber diagram. To obtain the high cycle fatigue life S-N curve of the film, the high cycle fatigue test was carried out by applying the constant amplitude load to the film specimen with three different stress ratio of 0.1, 0.3 and 0.5 and the frequency of 40 ㎐ at room temperature in air. The film specimen 15.26㎛ thick was fabricated by etching process. The fatigue limits and S-N curves at the respective stress ratios were determined from the experimental works. It was shown that the S-N curves were dependent on the stress ratio and the fatigue limit was increased with decreasing the stress ratio. The dependency of the fatigue behavior was presented in empirical relationship. Using these relationships, the fatigue limit was predicted.