• 수산해양기술연구
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• 제28권3호
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• pp.286-294
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• 1992

In this paper, the corrosion fatigue crack propagation behavior of structure rolled steel (SWS 41C) was investigated by changing the thickness, and this experiment was done by the three point bending corrosion fatigue tester. The main results obtained are as follows: 1) As the thickness of specimen becomes thicker, the corrosion sensitivity to initial stage crack becomes some sensitive, and that the fatigue life becomes more sensitive. 2) The crack growth rate to initial stage crack (da/dN) was retarded as the thickness of specimen becomes thicker. But after initial stage crack, as the thickness of specimen is more thicker, da/dN is more rapid. 3) As the corrosion fatigue crack length grows, the accelerative factor of thick specimen (t=12mm) is more higher than that of thin specimen (t=6mm). 4) As the corrosion fatigue crack length grows, the corroson potential of both thick specimen and thin specimen becomes more less noble potential, however thick specimen (t=12mm) tends to more less noble potential than that of thin specimen(t=6mm).

• Archives of Pharmacal Research
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• 제26권12호
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• pp.1036-1041
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• 2003

Two chitosanases produced by Aspergillus fumigatus KB-1 were purified by ion exchange and size exclusion chromatographies. Molecular weights of chitosanases were 111.23 kDa (chitosanase I) and 23.38 kDa (chitosanase II). The N-terminal amino acid sequence of chitosanase II was determined as follows: YNLPNNLKQIYDKHKGKXSXVLAKGFTN. The optimum pH of the chitosanase I and II was 6.5 and 5.5, respectively. The optimum temperatures were $60^{\circ}C$ for chitosanase land $70^{\circ}C$ for chitosanase II. Hydrolysis products of two chitosanases were analyzed by HPLC and GPC. Chitosanase I hydrolyzed substrate to glucosamine. Chitosanase II produced chitooligosaccharides.

• 한국해양공학회지
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• 제1권2호
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• pp.83-92
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• 1987

Inorder ot estimate the running life of turbine rotors, fatigue crack propagation low, da/dN = C(${\DELTA}K)^m$, proposed by paris et al. has been widely applied. In this study, fatigue crack propagation rates for 16 samples of 1% Cr-Mo-V rotor steel were measured and statistical characteristics of m and C values in above equation were reviewed. The results are summarized as follows. 1. C and m follow a log-normal distribution and normal distribution, respectively. And the relation of C and shows a strong negative correlation. 2. Fatigue crack propagation equation can be expressed as da/dN=$4.11{\times}10^{-4}({\Delta}K/153.8)^m$, introducing the ralationship C=$C_oK_o^{-m}$. In this case, contribution of $C_o$ distribution to the distribution of log C shows very small compared to degrees of contribution by m.

• Carbon letters
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• 제7권1호
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• pp.9-18
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• 2006

Activated carbons were obtained by activating wild cherry stones with different concentrations of phosphoric acid or zinc chloride at different temperatures. The adsorption of $N_2$ at 77 K and of $CO_2$ at 273 K was followed and the data were analyzes by considering different adsorption models. The activated carbons obtained measured high surface area with the most of the surface in all samples located in micropores. Fair agreement was found between the nitrogen surface areas calculated from the BET-, t-, ${\alpha}$- and DR- methods, although the first three are based on surface coverage whereas the latter is based on micropore filling. The carbon dioxide surface areas calculated by the DA equation were smaller than the comparable nitrogen areas. This was ascribed to domination of surface coverage mechanism, the absence of activated diffusion process. Based on this explanation the $CO_2$-surface areas as calculated by DA equation should be taken with great reservation.

• 한국안전학회지
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• 제11권2호
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• pp.3-8
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• 1996

Fatigue fracture is the cyclic fracture phenomena at a very small local area near a crack tip. Therefore, the detailed quantitative experimental analysis about local cyclic strain distribution near a crack tip is prerequisite In order to make an effective parameter able to account for fatigue fracture problems. However, there are few reports on detailed quantitative experimental analysis of a local cyclic strain distribution near a crack tip, because of experimental difficulties. In this study, the distribution of local fatigue strains near a fatigue crack tip was in detail studied using by fine dot grid strain measurement method. From these results, a single parameter, which characterizes local fatigue strain field, was proposed. In addition, this parameter was applied to evaluate the fatigue crack propagation rate.

• 생명과학회지
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• 제12권5호
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• pp.555-560
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• 2002

연접후치밀질(PSD)의 분자조성은 아직 대체로 알려져 있지 않다. 본 연구에서는 다양한 크기의 연접후치밀질 단백질들을 효율적으로 SDS-겔에서부터 추출하는 방법을 제시하고, 이를 이용하여 연접후치밀질의 1% n-octyl glucoside에 용해되지 않는 분핵에 존재하는 31kDa크기의 단백직(PSD31로 명명)을 SDS-겔로부터 분리하고, trypsin 처리하여 생성되는 펩티드의 아미노산 서열을 결정하였다. PSD31의 아미노산 서열은 adenine nucleotide translocator 1(ANT1)과 매우 상동성이 높았다. 연접후치밀질에 ANT1이 존재함은 신경조직의 세포외 공간에 adenosine nucleotide를 유리할 수 있는 기구가 연접에 존재함을 시사한다.

• 한국수정란이식학회:학술대회논문집
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• 한국수정란이식학회 2002년도 국제심포지엄
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• pp.108-108
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• 2002

포유동물의 암컷 생식기관에 존재하는 다양한 종류의 matrix metallo-proteinase (MMP)는 난소와 자궁의 구성성분의 주기적인 변화를 조절하며 이중 난소의 MMP는 난포의 성장과 배란 그리고 퇴화 동안 조직재구성에 매우 중요한 역할을 한다고 알려져 있다. 본 실험에서는 근래에 새로 발견된 사람의 난포액에 존재하는 분자량 약 110kDa인 MMP-2 isoform GA110을 동정하고 자 하였다. 난포액으로부터 GA110 단백질을 분리하기 위하여 난포액에 5mM ethylenediaminetetraacetic acid(EDTA)를 처리한 후 DEAE Sepharose Fast Flow를 이용한 chromatography를 시행하였다. 그 결과, 난포액 단백질들은 0.2M NaCl 의 분획에서 GA110 활성을 나타내었고 anti-human MMP-2 antibody에 대한 면역반응도 뚜렷이 나타났다. DEAE Sepharose Fast Flow에서 얻은 분획 중 GA110의 활성과 면역반응을 모두 나타내는 분획만을 모아 Gelatin Sepharose 4B affinity chromatography로 다시 분리하였다 분리한 결과 resin에 흡착된 단백질 (eluate) 분획들에서 매우 뚜렷한 GA110 gelatinase 활성을 나타내었으며 면역반응 또한 관찰되었다. 이 분획들의 단백질을 농축한 후 zymography를 시행하여 나타난 GA110 단백질 band를 잘라 내었으며 이로부터 단백질을 electroelution하여 농축한 후 reducing agent인 2-mercaptoethanol를 처리하였다. 이를 전기영동 후 MMP-2 (propeptide region) antibody를 사용하여 immunoblotting 한 결과 70-72kDa의 단백질만이 면역반응을 나타내었다. 마지막으로 위와 같이 준비된 70-72kDa 단백질의 아미노산 서열을 Edman degradation 방법으로 분석하였다. 그 결과 이 단백질의 N 말단의 10개의 아미노산 배열 순서가 알려진 사람의 proMMP-2의 전체 배열순서 중 propetide domain의 N 말단에서부터 다섯 번째에서 시작하여 10개의 아미노산의 서열과 정확하게 일치하였다. 위 결과들로 미루어 사람의 난포액에 존재하는 MMP-2의 새로운 isoform인 GA110은 70-72kDa의 ProMMP-2가 disulfide bond를 통해 homodimer 구조를 이루고 있는 것으로 여겨진다.

• 대한화학회지
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• 제38권7호
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• pp.509-515
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• 1994

고리(12C4, 15C5, 18C6, DT18C6, DA18C6) 및 비고리$(Q_2O_5)$ 폴리에테르와 11가지의 1차 및 2차 알킬암모늄 이온과의 상호작용을 NMR 적정과 전기전도도법으로 조사하였다. 모든 알킬암모늄 이온은 크라운 에테르 및 비고리 폴리에테르와 수소결합에 의해 비교적 안정한 1:1 착물을 형성하였다. 알킬암모늄 이온과 동공의 크기가 다른 동일계열 호스트와의 상호작용의 세기는 18C6 > 15C5 > 12C4 순이었으며, 알킬암모늄 이온에 대한 호스트 주개원자의 세기는 N > O > S 순이었다. 18C6는 2차 알킬암모늄 이온에 비해 1차 알킬 암모늄 이온과 더 강한 상호작용을 하는 반면, DA18C6는 2차 알킬암모늄 이온과 더 강한 상호작용을 하였다. 또한 25$^{\circ}C$ 메탄올에서 18C6와 알킬암모늄 이온과의 착물형성에 대한 안정도 상수를 전기전도도법에 의해 구하였다. 착물의 안정도는 주로 알킬암모늄의 차수(또는 수소결합 수), 알킬기의 길이, 알킬기의 구조에 의한 입체장애 등에 의해 크게 영향을 받았다.

• 한국식품영양과학회지
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• 제28권2호
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• pp.285-291
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• 1999

To confirm the food quality of Urechis unicinctus which have been favored as a special raw seafood in southern area in Korea, the chemical composition of Urechis unicinctus and those glycoprotein were studied. Freeze dried Urechis unicinctus was composed of more than 70% of crude protein and 15% of total carbohydrate. The amino acids such as glycine(18.69%), glutamic acid(12.50%) and aspartic acid(9.37%) were noted as major components of total amino acids. The predominant free amino acids were alanine(32.98%), glycine(27.50%), asparagine(19.65%) and taurine(8.29%), and the sum of them were more than 88% to total free amino acids, so they may cause unique taste of Urechis unicinctus with sweetness. As the basis of sugar composition analysis, 56.35% of glucose and 30.49% of N acetylglucosamine were contained respectively, and they might also play an important role in a sweet taste. The leading carbohydrate moiety of glycoprotein from Urechis unicinctus was identified as glucose and N acetylglucosamine similarly to raw muscle, and they occupied more than 50% of total sugar content. Fucose(18.32%) and D glucuronic acid(12.31%) also detected in higher levels com pared to raw muscle. The total amino acid profile of glycoprotein showed a similar trend to raw muscle protein but glycine was detected a significantly lower than that in raw muscle. The glycoprotein from Urechis unicinctus was composed of 4 kinds of subunits, i.e. 25kDa, 20kDa, 18kDa and 12.5kDa of molecular weights through the SDS polyacrylamide gel electrophoresis. On the basis of the IR spectrum of absorptions appeared in 1,240cm-1 and 850cm-1, the glycoprotein had sulfate groups.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.291-294
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• 2005

The microstructure evolution of Alloy 718 during the direct age(DA) process was predicted using the recrystallization model and finite element analysis. The DA process of Alloy 718 was performed in two-step forging using capsulated cylindrical billets of 122mm in diameter and 180mm in height. In order to evaluate the microstructural change during the forging, a dynamic recrystallization model of Alloy 718 was implemented onto the user-subroutine of the commercial FEM code. The prediction of microstructure evolution in DA processed Alloy 718 pancake was compared with experimental results.