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Al-bronze에 있어서 직접차분법에 의한 2차원 응고해석에 관한 연구
최정길,정운재,김동옥,Choe, Jeong-Gil,Jeong, Un-Jae,Kim, Dong-Ok 한국기계연구원 1987 기계연구원소보 Vol.17 No.-
Two dimensional computer simulation of solidification behavior using FDM as simulation tool was applied to AI-bronze casting. By the comparison of computer simulation with the experimental results, it was showed that the final shrinkage position and solidification time are good accordance with results of computer simulation. It is expected that this software will be widely applied to casting design or rise ring for directional solidification.
국내자원을 활용한 가탄재의 (加炭材) 개발에 관한 연구 (2)
최정길,김동옥 ( J . K . Choi,D . O . Kim ) 한국주조공학회 1982 한국주조공학회지 Vol.2 No.3
N/A For the purpose of development of domestic carburizer, when the basicity of ash in carburizer was changed from Na₂O/Al₂O₃+ SiO₂; 0.06 to Na₂O/Al₂O₃+SiO₂: 0,196wt%, using Na₂O as flux for domestic graphite resource (Bong Myung armorphous graphite), carburizing efficiency was improved as basicity increased, optimum basicity value was Na₂O/Al₂O₃+ SiO₂; 0.151. This means that Na₂O contributed to lower viscosity of slag and raise occurence probability of specific reaction surface between molten iron and carburizer. The experiment of effect of general characteristics offecting carburizing ability of this carburizer was performed, the result is that 10/30 mesh was optimum size of the carburizer and as carbon equivalent of molten iron was higher, carburizing ratio was lowered, but when si concentration was below 1.8% in general cast iron melting region, recovery showed 75-85%. As agitation rate of molten iron and temperature interval were higher, Carburizing ratio was increased and showed max, 94%. Desulfurizing phenomena of molten iron by Na₂O in carburizer didn`t appear.
최정길,김성빈,홍준표 ( Jeong Kil Choi,Seoung Bin Kim,Chun Pyo Hong ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.1
N/A A computer simulation of mold filling has been performed in order to analyze the fluid flow pattern in a mold cavity since casting defects such as cold shut formation, entrapment of air or gas, and inclusions are closely related to the fluid flow phenomena. The flow of molten metal entering the mold cavity with free surface has been modeled by SMAC(Simplified Marker and Cell) method. Two dimensional analysis was carried out on plate shape castings with two types of gate system. The calculation results were compared with those of water modeling experiments and showed relatively good agreement.
최정길,김동옥 ( Jeong Kil Choi,Dong Ok Kim ) 한국주조공학회 1986 한국주조공학회지 Vol.6 No.1
The gating design of gray cast iron was programmed in a Personal computer. By this program, casting test was done. The results obtained are as follows. 1. Gating design that can calculate the velocity of metal flow and size in each gate section by knowing the loss coefficient caused by friction loss and bend loss was programmed. 2. In the test casting, the gating ratio was changed into 1.1:1.3:1, 1:2:2, 1:4:4. And sound casting, free of sand washing defect, was obtained at the velocity of 35.5㎝/sec in ingate.
김기영(Ki Young Kim),김정태(Jung Tae Kim),최정길(Jung Gil Choi) 한국주조공학회 2002 한국주조공학회지 Vol.22 No.4
N/A Dimensional defects of castings are mainly due to the stresses and strains caused by a nonuniform temperature distribution and phase transformation during solidification and cooling, and by mechanical constraint between the mold and casting. It is, however, nearly impossible to trace movements of the casting and mold during solidification and cooling by experimental measurements for castings with complex shape. Two and three dimensional deformation analyses of the casting and the mold were performed using commercial finite element code, MARC. It was possible to calculate deformation and temperature distribution in the casting and mold simultaneously. Cooling curves of the casting obtained by calculation were close to that measured in the field since it was possible to treat latent heat evolution of the casting which could be divided into two parts, primary and euctctic parts. Mold bent inward just after pouring due to the temperature gradient across the mold thickness, and mold returned to its previous position with time. Plastic deformation occurred at the part of the casting where solidification was slow.
최정길(Jungkil Choi),김태하(Teaha Kim),이효진(Hyojin Lee) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.5
최근 선박을 이용한 국제교역의 증가로 항만 및 선박의 규모가 대형화되었다. 선박은 벙커C와 MDO(Marine Diesel Oil)를 연소하여 전기를 생산한다. 선박에서 배출되는 NOx, SOx, PM, CO는 대기오염의 원인이고, 항만 노동자와 인근 주민들의 건강에도 상당한 영향을 미친다. 국제적으로 대기오염물질 저감에 관한 배출규제가 진행됨에 따라 선박과 하역장비, 물류수송 트럭, 기관차에서 배출하는 대기오염물질의 양을 산정하는 연구가 국외에서 수행되었다. 하지만 한국은 선박에 의한 대기오염물질 배출에 관한 연구가 미흡하다. 본 연구는 우리나라 주요 항만인 인천, 광양, 부산, 울산을 대상으로 입항하는 선박의 배기가스 배출량을 산정하였다. 또한 배출된 배기가스에 의한 사회적 비용도 산정하였다. 그 결과, 선박의 입항횟수가 많은 부산에서 배기가스 배출량과 사회적 비용 부담이 높았다. 선종별로는 4개 항에 입항횟수가 많았던 유조선이 배출량과 사회적 비용 부담이 높았다. The recent increase in international trade using vessels has increased the size of ports and vessels. The ship produces electricity by burning bunker C and Marine Diesel Oil (MDO). NOx, SOx, PM, and CO emitted when ships burn fuel cause air pollution and have a significant impact on the health of port workers and neighbors. As international regulations on air pollutant reduction have been carried out, studies to estimate the amount of air pollutants emitted by ships, cargo handling equipment, logistics transportation trucks, and locomotives have been conducted abroad. However, Korea has insufficient research on the emission of air pollutants by ships. This study estimates the exhaust gas emissions of ships entering Incheon, Gwangyang, Busan and Ulsan, the major ports in Korea. In addition, the social cost of the exhaust gas was calculated. As a result, exhaust gas emissions and social cost burdens in Busan were high. By ship type, the tankers that frequently entered four ports had high emissions and social cost burden.
최정길 ( Jung-kil Choi ),이효진 ( Hyo-jin Lee ),김태하 ( Tea-ha Kim ),최재훈 ( Jea-hun Choi ),우준식 ( Jun-sik Woo ),이강웅 ( Kang-wung Lee ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.3
Nitrogen budgets in Sihwa-ho in 2010 were estimated using a mass balance approach. Major nitrogen fluxes sources can be divided into three sections: cities, agricultural area, and forest. Surplus nitrogen 2,030~2,214 ton/yr (2,123 ton/yr in average) was discharged to Sihwa Lake. 20% of the surplus nitrogen is removed from the wetland and 60% is removed tidal flats. Therefore net nitrogen discharge from Sihwa basin is estimated to be 650 708 ton/yr (679 ton/yr in average). Wet and dry nitrogen deposition and load from non-point sources ware estimated to be 97 ton/yr and 69 ton/yr, deposition is using CAMx model. So estimated total nitrogen discharge into Sihwa-ho was 817 875 ton/yr (846 ton/yr in average). The atmospheric load explains 11.1 11.9% (11.5% in average) of the total nitrogen load Sihwa-ho.