• Journal of the Korean Society for Heat Treatment
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• v.36 no.3
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• pp.153-160
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• 2023

The use of biogas is an industrially necessary means to achieve resource circulation. However, since biogas obtained from waste frequently causes corrosion in pipes, it is important to elucidate corrosion mechanisms of the pipes used for biogas transportation. Recently, corrosion failure occurred in a pipe which supplied for the biogas at the speed of 12.5 m/s. Pinholes and pits were found in a straight line along the seamline of the pipe. By using corrosion-damaged samples, residual thickness, microstructure, and composition of oxide film and inclusion were examined to analyze the cause of the failure. It was revealed that the thickness reduction of biogas pipe was ~0.11 mm per year. A thin sulfuric acid film was formed on the surface of the interior of a pipe due to moisture and hydrogen sulfide contained in a biogas. Near the seamline, microstructure was heterogeneous and manganese sulfide (MnS) was found. Pits were generated by micro-galvanic corrosion between the manganese sulfide and the matrix in the interior of the pipe along the seamline. In addition, microcracks formed along the grain boundaries beneath the pits revealed that hydrogen-induced cracking (HIC) also contributed to accelerating the pitting corrosion.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.598-603
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• 2008

In petrochemical complex, Hydrogen Network optimization is surveying the extra Hydrogen and needed Hydrogen of each company and calculating the optimized distribution. This paper compares the case of using the existing pipeline and the case of not using the existing pipeline to show the effect quantitatively and clearly by modeling the both cases and using mathematical programming. As a result, using the existing pipeline can save the pipe cost over 20% and increase the whole network benefit by thirteen billion won.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.185-192
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• 2011

This study deals with a basic proposal to prove the safety for the exhausted fittings of the hydrogen fuel cell vehicle. First, this study was approached to numerical analysis solving to close the exact boundary condition (Axial, Bending, Lateral) and the second, this study produced the Lateral movement equipment for the vibration. For the numerical analysis, This study was considered with the exact solution of Lateral movement and the resonance effect for durability sample according to fitting positions. The second, This study was made for special equipment for displacement/gas leak and the frequency because the domestic samples were comparing with foreign fitting and foreign fitting for the hydrogen fuel cell vehicle. The result of this study was satisfied with domestic fittings for the basic reference but it need more test because of other situation for hydrogen fuel cell vehicle.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1513-1520
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• 2009

Renewability and pollutant free energy source makes hydrogen energy popular rapidly. Hydrogen gas pressure which is after passing through reciprocating compressor part has high pulsation wave form. A unit, snubber is used as compressor components to reduce the harmful pulsation waveform and to remove the impurities in the hydrogen gas. An experiment has been conducted to investigate the pulsation reduction performance of a steel pipe used in snubber system. The amplitude of pressure reduction were varied from $0.054{\sim}0.321\;kPa$ for 10 hz to 60 hz motor speed. Compressor operation by motor with 10 to 60 hz were resulted in reduction of pressure pulsation from 16.415% to 35.151%. Pressure losses were varied from $0.001%{\sim}0.759%$, and pressure drop per centimeter of the steel pipe were varied from $0.0160{\sim}16.03\;Pa$.

• Transactions of Materials Processing
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• v.27 no.1
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• pp.54-59
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• 2018

In connecting parts of a hydrogen fuel cell vehicle, since the rubber ring is permeable to hydrogen, it is necessary to use a metal sealing structure which ensures leakage stability. Finite element analysis was performed to verify the fitting characteristics of the metal sealing structure, which is used to connect the pipe to a high pressure hydrogen FCEV tank. Deformation shape, contact distance and axial load were compared experimentally and these values were in agreement with each other. In the contact surface, between the pipe and the fitting body, the stress at the edge of the contact surface was higher than the center point, which was considered to be a good characteristic in view point of the leakage. The location of the contact points has almost no change in the upper part of the fitting, but that of the lower parts move downward as the fastening amount increases. The contact pressure at the lower part is maintained at the same constant level.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.165-175
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• 2013

This study aims to analysis correlation in septic tank and sewer pipe between odor substances and complex odor. For the analysis, convert odor substances to odor intensity, and estimate the effect of odor substances on complex odor. As a result, both Hydrogen sulfide and Methyl mercaptane of specified offensive odor substances accounted for 29 percent of the effect of odor substances on complex odor. Hydrogen sulfide and Methyl mercaptane are major cause of odor from septic tank and sewer pipe. The result of this study is suggested to be used as a preliminary data for research on analysis complex odor and odor substances.

• Journal of Hydrogen and New Energy
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• v.26 no.5
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• pp.463-468
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• 2015

This study describes the effect of upstream curved pipe on internal flow characteristics ball valve. Continuity and three-dimensional Reynolds-averaged Navier-Stokes equation have been used as governing equations for the numerical analysis. The upstream curved pipe - ball valve model was assumed that it is used for Alaska pipeline project which was planned to provide reliable transportation of natural gas from ANS to Alaska-Yukon border. Therefore the characteristics of pipe and operating condition of pipeline were from report of Alaska pipeline project. The three curvature and three location of upstream curved pipe were analyzed. The results shows that there are typical flow patterns at ball valve and the upstream curved pipe makes some differences to the internal flow of ball valve.

• Journal of Hydrogen and New Energy
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• v.13 no.1
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• pp.83-89
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• 2002

The goal of this research is to understand the NOx emission in direct injected diesel engine with premixed hydrogen fuel. Hydrogen fuel was supplied into the test engine through the intake pipe. Amount of hydrogen-supplemented fuel was 70 % basis on heating value of the total input fuel. The effects of intake air temperature and exhaust gas recirculation(EGR) on NOx emission were studied. The intake air temperatures were varied from $23^{\circ}C$ to $0^{\circ}C$ by using liquid nitrogen. Also, the exhaust gas was recirculated to the intake manifold and the amount of exhaust gas was controlled by the valve. The major conclusions of this work include: ( i ) nitrogen concentrations in the intake pipe were increased by 30% and cylinder gas temperature was decreased by 24% as the intake air temperature were changed from $23^{\circ}C$ to $0^{\circ}C$; ( ii ) NOx emission per unit heating value of supplied fuel was decreased by 45% with same decrease of intake air temperature; and (iii) NOx emission was decreased by 77% with 30% of EGR ratio. Therefore, it may be concluded that EGR is effective method to lower NOx emission in hydrogen fueled engine.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.1939-1950
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• 2019

The MELCOR code useful for a plant-specific hydrogen risk analysis has inevitable limitations in prediction of a turbulent flow of a hydrogen mixture. To investigate the accuracy of the hydrogen risk analysis by the MELCOR code, results for the turbulent gas behavior at pipe rupture accident were compared with CFX results which were verified by the American National Standard Institute (ANSI) model. The postulated accident scenario was selected to be surge line failure induced by station blackout of an Optimized Power Reactor 1000 MWe (OPR1000). When the surge line failure occurred, the flow out of the surgeline was strongly turbulent, from which the MELCOR code predicted that a substantial amount of hydrogen could be released. Nevertheless, the results indicated nonflammable mixtures owing to the high steam concentration released before the failure. On the other hand, the CFX code solving the three-dimensional fluid dynamics by incorporating the turbulence closure model predicted that the flammable area continuously existed at the jet interface even in the rising hydrogen mixtures. In conclusion, this study confirmed that the MELCOR code, which has limitations in turbulence analysis, could underestimate the existence of local combustible gas at pipe rupture accident. This clear comparison between two codes can contribute to establishing a guideline for computational hydrogen risk analysis.

• Journal of the Korean Society of Safety
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• v.39 no.1
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• pp.27-32
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• 2024

This study analyzed cases of hydrogen (H₂) and natural gas (CH₄) leakage from a hydrogen-blended natural gas pipeline to determine a range of leakage characteristics, including leakage type, pipe material, pipe diameter, pressure, and damage size. Based on the results of this analysis, five hydrogen-blended natural gas leakage scenarios were selected. The national vision for a carbon-neutral society by 2050 is a very important strategic objective and promotes environmentally sustainable economic development in the age of the climate crisis. Accordingly, zero-carbon and low-carbon policies are being promoted in various fields, including energy production, consumption, and industrial processes. Hydrogen-blended natural gas is eco-friendly and is considered an important step towards carbon neutrality, with various countries including the United States and several European countries conducting empirical research to further investigate its potential. In Korea, a national research project commenced in April 2023 to verify and demonstrate the life cycle safety of blending hydrogen into the natural gas network. The results of this study will provide important data for the analysis of the damage impacts caused by the leakage of hydrogen-blended natural gas, such as the diffusion of gas clouds, fires, and gas explosions.