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Flow Analysis of Ultra-high Pressure Needle Valve for Hydrogen Charging Station
J. A. Choi(최지아),J. H. Kim(김주현),M. G. Park(박민규),J. H. Yun(윤진호),Y. J. Cho(조영진),J. S. Jang(장지성) 유공압건설기계학회 2021 유공압건설기계학회 학술대회논문집 Vol.2021 No.11
Hydrogen energy is the clean energy of the future. While research to safely use such hydrogen gas is being actively conducted, hydrogen charging stations have been installed and used as vehicle fuel. Ultra-high pressure hydrogen is used at hydrogen refueling stations, and parts are being developed accordingly. On the other hand, the ultra-high pressure valve, which is one of the parts, is dependent on foreign countries, and the level of domestic research on this is about 10% of that of overseas advanced technologies. In this study, the flow characteristics inside the needle valve using ultra-high pressure hydrogen gas were analyzed using three-dimensional numerical analysis. The flow characteristics according to the displacement of the needle were analyzed, and the SST (Shear Stress Transport) model is used for the turbulence analysis model. The flow coefficient was calculated according to ISA 753.02.01 for valve capacity test using the numerical analysis results. Finally, the flow coefficient according to the displacement of the needle was presented as a graph.
송재용 ( J Y Song ),사승훈 ( S H Sa ),남정우 ( J W Nam ),김진표 ( J P Kim ),조영진 ( Y J Cho ),오부열 ( B Y Oh ) 한국안전학회(구-한국산업안전학회) 2012 한국안전학회지 Vol.27 No.2
This paper describes electrical fire on electric pad caused by defect of hot wires, We analyzed two type electric-using by carbon type hot wire and magnetic shielded type hot wire, First, a carbon type hot wires electric-is virtually impossible to connect hot wire as a method of electrical welding or soldering, In order to connect between hot wires, that has to splice carbon type material connector, If junction of hot wires was occurrence of poor connection on electric pad, it increase contact resistance on this junction point With increasing contact resistance, junction of hot wires on electric-generates local heating and finally leads to electrical fire. An electric-using by a magnetic shielded type hot wire happened local heating on signal wire for sensing temperature-rise caused by applying current for magnetic shielded. With increasing local heating of signal wire, insulated coating of hot wire was melted. Finally the magnetic shielded type hot wire electric pad lead to electrical fire with breakdown between signal wire and hot wire, In this paper, we analyzed shape of damage in hot wire caused by electrical local heating and investigated fire cause on electric pad due to defect of hot wires.
송재용 ( J Y Song ),김진표 ( J P Kim ),조영진 ( Y J Cho ),최돈묵 ( D M Choi ),오부열 ( B Y Oh ),길경석 ( G S Kil ) 한국안전학회(구 한국산업안전학회) 2012 한국안전학회지 Vol.27 No.4
This paper describes electrical fire on residential environment such as apartment and detached house caused by defect of interior wiring. We carried out experimental study on short circuit characteristics by the interior wiring length We were measured arc current, arc energy and interrupting time of earth leakage current circuit breaker(ELB), when an interior wiring break out short circuit in residential environment. From the experiment results, the longer of the interior wiring, the magnitude of arc current decreased and the interrupting time of ELB increased. When applied the A maker`s ELB, the strength of arc current and interrupting time of ELB was 254 A and 245 ins respectively at 30 m interior wiring length, In 3 m interior wiring length, arc current and interrupting time was 716 A and 4.24 ins respectively. Arc energy was dependent on the magnitude of arc current and the interrupting time of ELB, the longer the interrupting time, arc energy increasing. In this paper, minimum arc energy was 277 J using C maker`s ELB and 3 m interior wiring length (arc current 283 A, interrupting time of breaker 6.28 ms). Therefore in the residential environment, short circuit caused by defect of the interior wiring lead to electrical fire.
이덕보(D. B. Lee),김정현(J. H. Kim),강수근(S. K. Kang),조영진(Y. J. Cho),장석원(S. W. Chang),임재훈(J. H. Lim),유동수(D. S. Ryu) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
The opening test of a filament is very important for the reliability of fluorescent lamps. Failure mechanisms of filament in fluorescent lamps are investigated by the filament accelerated stress test and voltage accelerated stress test. The characteristics of the accelerated test data are also compared with those of field data. The failure sites of filament in fluorescent lamp were occurred at the middle part of filament due to radiant heat and the edge part of filament due to torsional stress caused by thermal stress. It found that the life time of fluorescent lamp was effected by the cooling time and the structure of filament.