• 한국주조공학회지
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• 제18권6호
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• pp.555-562
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• 1998

Modified fluid critical solid fraction method was utilized as a prediction parameter to describe the shrinkage formation including the position, shape and amount of shrinkage cavities. A numerical scheme was implemented adapting this method for the evaluation of solidification defects in various casting processes. In the present numerical code, the form of shrinkage cavity can be simultaneously determined when an isolated loop is predicted to occur by the fluid critical solid fraction method. An auxiliary parameter, shrinkage potential, was also used in order to calculate the amount of residual liquid during solidification. Solidification analysis was carried out for the validation of the present scheme. It was shown that the calculated results were in good agreement with those of practical casting runs in all of the casting processes envolved in the present research. It may be concluded that the present program successfully predicts the detailed shrinkage formation behavior without the consideration of interdendritic fluid flow analysis.

• 한국해양공학회지
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• 제10권4호
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• pp.84-91
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• 1996

A fractal analysis on fracture surface of aluminium-particulate SiC composites was attempted. As the volume fraction of SiC in composites increases, the fractal dimension tends to increase. However, no correlation between the fractal dimension and the fracture toughness in terms of critical energy release rate was observed. Since the fractal dimension represents the roughness of fracture surface, the fracture toughness would be a function of not only fracture surface roughness but also additional parameters. Thus the applicability of fractal analysis to the estimation of fracture toughness must depend on the proper choice and interpretation of additioal paramerters. In this paper, the size of characteristic strctural unit for fracture was considered as an additional parameter. As a result, the size appeared to be a function of only volume fraction of SiC. Finally, a master curve for fracture toughness of aluminium-particulate SiC composites was proposed as a function of fractal dimension and volume fraction of SiC.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제8권2호
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• pp.61-68
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• 2004

The purpose of this study is to develope and analyze the assessment items which can be used in evaluation of the fraction computation ability for fifth grade students. The item development team consists of three elementary school teachers and three mathematics education expert. The developed items was analyzed item analysis after applying to 135 fifth grade students. As a results of item analysis, it shows meaningful over the level of a standard basis: reliability: 0.80; validity: item 1(1.05), item 2(1.10), item 3(.85), item 4(.90), item 5(1.08); item difficulty: item 1(-.22), item 2(-.41), item 3(.23), item 4(.40), item 5(-.01); item discrimination: item 1(.73), item 2(.73), item 3(.67), item 4(.51), item 5(.56). This means that the test tool could be useful in the evaluation of the fraction computation ability.

• 소성∙가공
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• 제6권4호
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• pp.319-328
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• 1997

A flow stress involving strain, solid fraction, and breakage ratio, and solid fraction updating algorithm were proposed to depict the deformation behavior of materials at the semi-solid state. In case of isothermally simple upsetting of Sn-15%Pb alloy at the semi-solid state, by comparing the results of finite element analysis with the existing experimental results, the reliability of both the developed flow stress and updating algorithm were investigated. It was found that the verified program can effectively be used in the rigid-viscoplastic finite element analysis of the semi-solid forging processes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.73-78
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• 2000

On this study, the fatigue crack propagation of super duplex stainless steel is investigated in conditions of various volume fraction of austenite phase by changing heat treatment temperature. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis methods. As the temperature of heat treatment increased, volume fraction of austenite decreased and coarse grain was obtained. The specimen heat treated at $1200^{\circ}C$ had longer fatigue life and slower rate of crack growth. As a result of time-frequency analyze of acoustic emission signals during fatigue test, main frequency was $200{\sim}300kHz$ having no correlation with heat treatment and crack length, and 500kHz was obtained by dimple and separate of inclusion

• 생명과학회지
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• 제28권2호
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• pp.176-186
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• 2018

김(Porphyra yezoensis, Laver)의 MeOH 추출에 의한 유기용매 별 분획물에서 폴리페놀 함량과 항산화 활성 및 간암세포주 HepG2의 세포증식 억제효과를 확인하였다. $CHCl_3$ 분획물의 폴리페놀 함량은 $10.34{\mu}g/mg$으로 물 분획물의 $13.08{\mu}g/mg$ 보다는 다소 적게 나타났으나, DPPH 자유라디칼 소거에 의한 전자공여능(EDA)에서 나타난 $ED_{50}$은 $16.96{\mu}g/ml$로 가장 높게 나타났다. $CHCl_3$과 EtOAc 분획물은 농도의존적으로 HepG2 세포의 증식을 억제하였으며, 특히 $900{\mu}g/ml$의 $CHCl_3$ 분획물을 24시간 동안 처리하여 90%의 세포증식이 억제되었다. 한편 $CHCl_3$ 분획물이 처리된 HepG2 세포의 유전자 발현 양상을 microarray로 확인하였다. P. yezoensis의 효능과 연관지은 gene ontology 분석으로 비타민 D 합성 과정, 항균작용에 대한 반응 및 영양물질에 대한 반응에 관련된 유의 유전자들을 탐색하였다. 유의 유전자로 IL6R와 CYP1A1를 선정하였고, 이들 유전자의 상위 조절자는 ARNT 유전자가 선정되었다. 또한 50 및 $100{\mu}g/ml$의 $CHCl_3$ 분획물이 처리된 HepG2 세포에서 IL6R와 CYP1A1 단백질의 발현과 상위 조절자인 ARNT의 활성을 Western blotting으로 확인하였다.

• Environmental Analysis Health and Toxicology
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• 제1권1호
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• pp.27-36
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• 1986

Experiments were performed on mice to investigate the effect of Panax ginseng petroleum ether fraction on the immunotoxicity of lead acetate. Lead acetate was administered in the drinking water and ginseng p-ether fraction was injected intraperitoneally, Mice were sensitized and challenged with sheep red blood cell. Humoral immune responses were evaluated by antibody production and Arthus reaction. Pathotoxicological influences were measured by serum protein, alkaline phosphatase and total cholesterol. The weight of liver, spleen and thymus were measured. Lead acetate exposure significantly decreased hemagglutination titer, hemolysin titer, Arthus reaction, spleen and thymus weight. Ginseng p-ether fraction administration significantly restored or potentiated reduced humoral immune response, spleen and thymus weight. Reduced serum A/G ratio, total cholesterol and alkaline phosphatase activity were restored or increased by ginseng p-ether fraction administration.

• 한국식품영양과학회지
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• 제28권2호
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• pp.458-463
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• 1999

Methanol extract and its fraction of traditional fermented soybean paste(doenjang) from Soonchang area were studied for growth suppression on the various tumor cells and suppression components, by using HPLC and GC were analysed. Hexane fraction of methanol extract was indicated 79%, 76%, 67%, 66%, 78% of growth suppression on L1210, P338D1, HepG2, WiDr and SNU 1 tumor cells, respectively. Ethylacetate fraction of methanol extract also showed 81%, 75%, 75%, 76% and 82% of growth suppression on the same tumor cells, respectively. Peak 8 obtained from HPLC of ethylacetate fraction indicated 81%, 77%, 77%, 75% and 79% of growth suppression on the same tumor cells and identified as a genistein, by comparing with standard one by HPLC analysis. Hexane fraction of methanol extract contained oleic acid, linoleic acid and palmitic acid.

• 한국축산식품학회지
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• 제23권2호
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• pp.155-160
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• 2003

인유 초유로부터 지방을 제거하여 skim milk을 얻었다. 이것을 ultrafiltration을 한 후 gel filtration을 거쳐 EGF fraction 을 획득하였으며, 이를 SDS-PAGE로 확인하였다. hish performance liquid chromatography(HPLC)에 의해 EGF fraction을 분석한 결과, standard EGF 분석과 비교했을 때 31.545분대와 유사한 31.185분대에 peak가 나타난 것을 인하였다. 분리한 fraction 중 EGF 함유량을 측정하기 위해 immunoassay를 실시한 결과 건조중량 10 mg/mL 중에 약 10ng의 EGF가 포함되어 있는 것으로 측정되었다. SDS- PAGE후 실시한 western blot을 통하여 분리한 분획의 분리도를 확인하였다. 세포성장에 미치는 영향을 살펴본 결과, fibroblast cell인 BALB/3T3의 경우에는 건조중량 1 mg/mL 농도의 fraction 처리후 약 95%의 성장률을 보였으며, epithelial cell 인 IEC-6의 경우에는 약 71%의 성장률을 보였다.

• Journal of Ginseng Research
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• 제9권1호
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• pp.54-63
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• 1985

The free phenolic fraction from Korean white ginseng (Panax ginseng C.A. Meyer) was studied by GLC/MS as trimethylsilyl and methyl derivative. Five phenolic compounds such as 2,6-ditert butyl p-crestal, phloroglucinol, protocatechuic acid, isoferulic acid, quinic acid were identified newly. And additionally 13 organic acids and hydrocarbons were also identified in the fraction.