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고순도 Aluminum 에 있어서 가공경화가 활성화 Energy 에 미치는 영향
김동훈,황성현,이병휘 대한금속재료학회(대한금속학회) 1969 대한금속·재료학회지 Vol.6 No.4
99.9% 純度의 aluminum 試片을 加工硬化度에 따라서 恢復에 必要한 活成化 energy를 測定해 보았다. 4.75 ㎜ 直經의 aluminum捧을 10%, 20% 및 29%로 冷間壓縮加工을 實施하여 最終길이가 均一한 6 ㎜로 되게끔 하였다. 10% 및 29% 試片에 對하여 240∼330℃ 溫度區間에서 한時間 간격으로 isochronal annealing을 實施한 hardness data로부터 再結晶溫度가 304℃ 및 285℃ 임을 알 수 있었다. 한편 isochronal annealing을 290℃, 310℃, 및 330℃에서 實施한 結果 恢復에 必要한 活性化 energy는 각각 29,600㎈/㏖, 25,200㎈/㏖ 및 25,200㎈/㏖을 얻을 수 있었다. The effect of plastic deformation on the activation energy of recovery and recrystalization temperature of 99.9% purity polycrystalline Aluminum was investigated. The 10%, 20% and 29% cold compressed aluminum specimen were prepared from 4.75 ㎜ diameter cold drawn rod. From the hardness data obtained by isochronal annealing of one hour between the temperature range of 240℃-330℃ under hydrogen atmosphere, the recrystallization temperatures for 10% and 29% cold compressed were measured to be 304℃ and 285℃ respectively. On the other hand, from the hardness data obtained by isothermal annealing at the temperature range of 290℃-330℃, the activation energy of recovery for 10%, 20% and 29% cold compressed were deduced as 29,600, 25,200 and 22,500 ㎈/㏖ respectively. The activation energy of recovery can be expressible in linear equation in terms of the stored energy of plastic deformation.
저탄소강선의 열처리와 가공에 따른 기계적 성질에 대하여
김동훈,김원태 대한금속재료학회(대한금속학회) 1983 대한금속·재료학회지 Vol.21 No.5
Tenslle test and microstructural analysis were performed to investigate the effects of dual phase heat treatment and cold drawing so as to promote the mechanical properties of 0.07%C steel wire. The strength of the dual phase steel wires varied with volume fraction, shape, and size of martensite and grain size of ferrite. The strength of the dual phase steel wire was appromiately proportional to a reciprocal of square root of mean free path. The elongation of dual phase steel wires varied with volume fraction, distribution, and size of martensite. The carbon content in martensite changed the strength of martensite, which affected the elongation of the specimens. Low carbon steel wire of 1257 MPa in tensile strength and 4 percent in elongation was obtained, when low carbon steel rod with 475 MPa and 38% in tensile strength and elongation, respectively, was heat treated and cold drawn.
김동훈,이기형 보험연구원 2002 보험금융연구 Vol.36 No.-
손해보험의 종목별 적정수익률 결정과 관련하여 미국에서는 많은 연구가 있었지만 국내에서는 그렇지 못한 상황이다. 본 연구에서는 목표총수익률법과 자본자산가격결정모형, 현금흐름 할인모형을 이용하여 보험종목별 수익률의 수준을 실증적으로 추정하였다. 실증분석을 하여본 결과 대부분 보험종목의 보험수익률이 실제 적용하고 있는 수익률과 현저한 차이가 있으며 보험종목별로도 그 수준이 동일하지 않은 것으로 확인되었다. 따라서 국내에서도 보험수익률의 산출 및 적용방법, 적정수준에 대한 기준의 정립이 필요한 시점이라고 판단된다. This study analyses the appropriate level of fair rate of return for each insurance lines and shows the methodology to determine fair rate of return. In order to estimate fair rate of return for each lines, I employ methodologies used in the financial theory; target total rate of return, CAPM and discounted cash flow model. Our results can be summarized as follows; First, using the above methodologies, the estimated fair rate of return for each line is not identical and less than 5% of gross premium. Second, constructing the regulation standard and developing the estimation method for the fair rate of return, target total rate of return approach for estimation of fair rate of return is suggested.