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ADI의 미세조직과 기계적 특성에 미치는 특수열처리 및 합금원소의 영향
김석원,한상원,이익종,박진성,우기도,김동건 한국주조공학회 2003 한국주조공학회지 Vol.23 No.2
The effects of heat treatments and alloying elements on the microstructure and mechanical characteristics of specially austem-pared ADIs containing alloying elements such as Cu, Mo and Ni were investigated. To compare with the effect of conventional and normal(CN) austempering treatment, two kinds of special austempering treatments which pre-quenching and pre-heating were conducted. The hardness and uniaxial fatigue tests were carried out to evaluate the mechanical characteristics. The hardness of ADI treated by CN heat cycles was higher than those of other ADIs. Cu added ADI(Cu-ADI) tempered at 400 after austenitizing exhibited the highest fatigue life cycles. While austempering after prequenching makes the austenite with high carbon stable, which resulted in transformation to highly strengthened bainites from the carbon enriched austenite phases during tempering. The high carbon enriched banites is considered to improve the fatigue strength.(Received January 5, 2002)
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압력용기용 SA508 class3강에 대한 underclad 균열의 감수성 평가 - 입열량의 최적화
김석원,양성호,김준구,이영호 대한용접접합학회 1995 대한용접·접합학회지 Vol.13 No.2
Many pressure vessels for the power plants are fabricated from low alloy ferritic steels. The inner sides of the pressure vessels are commonly weld_cladded with austenitic stainless steels to minimize problems of corrosive attack. The submerged-arc welding(SAW) process is now used in preference to other processes because of the possibilities open to automation to reduce the overaII welding times. The most reliable way to avoid underclad cracks(UCC) which are often detected at the overlap of the clad beads is to use nonsusceptible steels such as SA508 class 3. At present domestically developed forging steel of SA508 cl.S is now being cladded with single layer by using 90mm wide strip, which transfers higher heat input into the base metal compared to the conventional two layers strip cladding which has been in wide use with 30-60 mm wide strip. But the current indices for the influence of heat input on crack susceptibility are not accurate enough to express the subtle difference in crack susceptibility of the steel. Therefore, the purpose of this present study is: l) To determine UCC susceptibility on domestic forging steel, SA508 cl.S cladded with single layer by using submerged arc 90mm strip and, 2) To optimize heat input range by which the crack susceptibility could be eliminated.
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김석원,윤훈용,Kim, Seok-Won,Yun, Hun-Yong,Lockhart, Thurmon 대한인간공학회 2006 대한인간공학회지 Vol.25 No.1
A laboratory study was conducted to evaluate if two different age groups(young vs. old) had differences in walking velocity and heel contact velocity and, furthermore, if these gait characteristics could adversely influence initial friction demand characteristics(i.e. RCOF) and the likelihood of slip-initiation. Twenty eight(14 younger and 14 older adults) participated in the study. While wearing a safety harness, all participants walked at their preferred gait speed for approximately 20 minutes on the linear walking track(1.5m× 20m) consisting of two floor-mounted forced plates. During subsequent 20 cameras, respectively. The results indicated that older adults walked slower(i.e., slower whole body center-of-mass velocity), exhibited lower heel contact velocity, and produced lower initial friction demand characteristics (i.e. RCOF) in comparison to younger adults. However, ANCOVA indicated that the diferences in heel contact velocity between the two age groups were due to the effects of walking velocity. The bivariate analysis further suggested that walking velocity was correlated to RCOF and heel contact velocity, while heel contact velocity was not found to be correlated to RCOF. In conclusion, could be a better indicator for predicting initial friction demand characteristics(i.e. RCOF) not hel contact velocity.
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교류열량계 제작 및 ZnS 광학박막이 증착된 유리기판의 열확산도 측정
김석원,김형근,박병록,한성홍,성대진 한국광학회 1996 한국광학회지 Vol.7 No.2
For the investigation of the influence of microstructure of optical thin films on the in-plane thermal diffusivity of glass substrate coated by that films, we constructed the AC calorimeter which uses argon-ion laser as a thermal source and measured several kinds of ZnS optical thin films which prepared by the changing of thermal evaporation speed such as 5$\AA$/s, 10$\AA$/s, 20$\AA$/s, 40$\AA$/s, 60$\AA$/s. The result showed that the thermal diffusivity decreases as the temperature increases. Also, when the evaporation speed is 20$\AA$/s, the thermal diffusivity has maximum value, and the variation of the thermal diffusivities are 27% at maximum.
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김석원,고석민,유장렬 한국식물생명공학회 2008 식물생명공학회지 Vol.35 No.1
Effects of growth regulators and culture conditions on seed germination, haustorium development, and callus formation of Korean mistletoe (Viscum album var. coloratum (Kom.) Ohwi) were described. Histological examination showed that seed of V. album contained one or two zygotic embryos with rod shape, and actively dividing cells were mainly distributed in radicle region rather than cotyledon of zygotic embryo. The most significant factor for seed germination and haustorium development of V. album was the requirement of the light. Various growth regulators examined in this study failed to substitute the effect of the light on seed germination. The frequency of callus formation was highest at 27.3% when flower buds were cultured onto B5 medium containing 0.1 mgl-1 IAA. Explants from other organs were recalcitrant in forming calluses. Culture conditions described in this study could be applied for production of useful metabolites and multiplication of V. album in future.
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김석원,김영국,한영재,박찬경,김진환,백광선 한국철도학회 2002 한국철도학회논문집 Vol.5 No.3
In this paper, we introduce the software and hardware of the measurement system for on-line testing and evaluation of high speed railway. The test items focus on the verification of the performance and acquirement of the technical data of the high speed railway system. The software controls the hardware of the measurement system, perform the analysis and calculation of measurement data and acts as interface between users and the system hardware. For this purpose, three programs a measuring program, a monitoring program and post-processing program are developed. The detailed test scenario is in the process of development to closely follow the process of development and design of the system.
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