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직류전원부하에 의한 zirconia와 금속의 접합에 관한 연구
김성진,임영우,오명훈 金烏工科大學校 1995 論文集 Vol.16 No.-
Effect of applying a DC voltage on the interfacial reaction at the metal to zirconia interface was investigated utilizing an oxygen ionic conductivity of partially stabilized zirconia. The joining of copper rod and zirconia tube was carried out in Ar gas atmosphere at 1000℃. There are two type of the joining. The one the reaction bond consisting of copper and zirconia was dominated by surface reaction with a undetctable very thin layer. It was found that copper elements were diffused to zirconia side, but that ?? ions were not diffused to copper side. There results mean application of a DC voltage to migrate oxygen to the copper-zirconia interface can oxidize metal st the copper-zirconia interface, and the bonding reaction between zirconia and copper oxide may occur. The other is the reaction bonding was dominated by interdiffusion with a very think interface layer. This result mean application of a DC voltage can reduce at the interface. The bonding reaction is to be an alloying between Zr and Cu.
Dry Deposition of Reactive Nitrogen and Sulfur Compounds in the Greater Seoul Area
Ghim, Young Sung,Kim, Jin Young 한국화학공학회 2002 Korean Journal of Chemical Engineering Vol.19 No.1
While deposition is a removal process of pollutants from the atmosphere, it is an intake process of such pollutants into the ground. It is suggested that surface waters in the Greater Seoul Area, used as a source of drinking water, have been affected by severe air pollution. In this work, the dry deposition of reactive nitrogen and sulfur species was estimated for three typical days in each season for the year of 1997. The CIT (California Institute of Technology) photochemical model incorporated with a gaseous oxidation reaction of SO_2 was used. The study revealed that reactive nitrogen deposition was the largest in summer and sulfur deposition was the largest in winter. Most of the reactive nitrogen was deposited in the form of HNO_3 and NO_2, but HNO_3 deposition is highly dependent on the season according to the extent of photochemical production. On the other hand, the contribution of sulfate to the total deposition of sulfur was minimal partly because of low deposition velocity and of the neglect of possible inflow from the boundaries. Approximately 53% of the reactive nitrogen and 30% of the sulfur emitted in the study area was deposited in the ground in the dry form on an annual basis.
A Commentary on Air Pollution Monitoring Programs in Korea
Ghim, Young-Sung,Kim, Jin-Young,Shim, Shang-Gyoo,Moon, Kill-Choo Korean Society for Atmospheric Environment 2002 한국대기환경학회지 Vol.18 No.E1
Air quality issues in Korea rapidly changed at the beginning of the 1990s from primary to secondary pollutants starting in Seoul, the capital of Korea. The present frame of national air pollution monitoring networks was established between the end of the 1980s and the beginning of the 1990s. Background monitoring was initiated in the middle of the 1990s in response to increasing public concern about the long-range transport of air pollutants. Apart from the national monitoring, both routine and intensive measurements of fine particles have been made for research purposes since the middle of the 1990s at several background sites. However, air pollution monitoring in urban areas for other purposes was relatively scarce as national monitoring has been concentrated in these areas. Although ozone pollution has become a significant issue in major metropolitan areas every summer, only a little information on ozone precursors is available. During the past few years, the number of national monitoring stations has greatly increased. The government has a plan to gradually expand monitoring items as well as stations. It is anticipated that highly detailed information on both photochemical reactants and products will be available within the next several years. More emphasis will be placed on toxic substances based on risk assessment in monitoring for both research and policy making.
김영성 ( Young Sung Ghim ) 한국공업화학회 1992 공업화학 Vol.3 No.2
Annual amount of plastics waste including rubber and leather waste, generated in 1990 was about 2,600,000 tons. Amount of generation of plastics waste has rapidly increased, but fractions of recycling and incineration have gradually decreased. Recently, two-stage incinerator, consisting of gasifier and gas combustor, draws much attention in Korea. Plastics are gasified in the starved air condition in the gasifier and produced gas is fired in the combustor. Combustion of produced gas is much easier than that of solid plastics, and produces a little pollutants. Standardzation of technology and process automation are still needed, but this incineration technology is in the commercial stage. Next topic concerned with this two-stage incineration will be how to treat complex plastics waste including toxic substances generated from automobiles and household appliances. Pyrolysis, realized by indirect heating in inert atmosphere, can provide high-quality products with minimum emissions. Many plastics are easily decomposed into oil in pyrolysis conditions, which can be utilized as chemical feedstocks, or gasoline or kerosene depending on feed materials and operating conditions. This has been demonstrated in several pilot-scale tests performed in Japan, Germany, etc. Easy removal of HCl from PVC is one of the most decisive merits of pyrolysis process. But in general, further efforts should be made for the process to obtain marketability. The future of pyrolysis process depends on public concern about environmental problems and oil prices.