Effect of Phenolic Compounds on Tobacco 6-Phosphogluconate Dehydrogenase

손혜정,김승수,Sohn, Hye-Jeong,Kim, Soung-Soo 생화학분자생물학회 1986 한국생화학회지 Vol.19 No.2

담배 callus (Nicotiana tabacum L. var. Virginia 115)에서 정제한 6-phosphogluconate dehydrogenase에 대한 여러 phenol 화합물의 영향을 조사해 본 결과, chlorogenic acid, esculin과, scopoletin은 모두 이 효소에 대하여 noncompetitive inhibitor로 작용하였으며 $K_i$ 값은 각각 $260\;{\mu}M$, $230\;{\mu}M$, $150\;{\mu}M$이었다. 또한 이 효소는 높은 농도의 caffeic acid와 ferulic acid에 의하여 약간 억제되었으며, 낮은 기질농도에서는 p-coumaric에 의해서도 억제되었다. 그 밖에 erythrose-4-phosphate, indole-3-acetic acid와 aromatic amino acids는 효소의 활성도에 아무런 영향을 미치지 못하였다. Effect of various phenolic compounds on the activity of tobacco 6-phosphogluconate dehydrogenase were studied. The enzyme was markedly inhibited by chlorogenic acid, esculin, and scopoletin noncompetitively with $K_i$ values of $150\;{\mu}M$, $230\;{\mu}M$, and $260\;{\mu}M$, respectively. The enzyme was also inhibited by caffeic acid and ferulic acid at high effector concentration (0.4 mM) and by p-coumaric acid at low 6-phosphogluconate concentration ($30\;{\mu}M$). All of the above phenolic compounds are known to be natural components of tobacco plants. Erythrose-4-phosphate, indole-3-acetic acid, and aromatic amino acids did not affect the activity of the enzyme significantly.

담배 6 - Phosphogluconate Dehydrogenase Band Il 의 동일 Subunits 에 관한 화학적 증거

손혜정,김은성,김승수 ( Hye Jeong Sohn,Eun Sung Kim,Soung Soo Kim ) 생화학분자생물학회 1985 BMB Reports Vol.18 No.4

6-Phosphogluconate dehydrogenase band II isoenzyme was isolated from a tobacco callus culture line, Nicotiana tabacum L., var. Virginia 115, utilizing ammonium sulfate precipitation, DEAF-cellulose chromatography, Red Sepharose CL-6B affinity chromatography followed by Sephadex G-150 gei filtration. N-terminal amino acid of the purified enzyme by dansylation method was lysine. Amino acid analysis indicated that the enzyme had 11 lysine and 17 arginine per 45,000 molecular weight subunit. Approximately 30 ninhydrin-positive spots were observed from tryptic peptide mapping study. Therefore, the results of N-terminal amino acid analysis, amino acid composition, and tryptic petide mapping suggest that the dimeric 6PG DH is composed of chemically identical subunits.

API 2W Gr. 50 강재 용접부의 피로균열전파거동의 거시적 및 미시적 관찰

손혜정(Hye-Jeong Sohn),김선진(Seon-Jin Kim) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.5

It is well known that a considerable amount of scatter is shown in experimental results relating to fatigue crack growth even under identical and constant amplitude cyclic loading conditions. Moreover, flux cored arc welding (FCAW) is a common method used to join thick plates such as the structural members of large scale offshore structures and very large container ships. The objective of this study was to investigate the macro- and microscopic observations of the fatigue crack growth (FCG) behavior of the FCAWed API 2W Gr. 50 steel joints typically applied for offshore structures. In order to clearly understand the randomness of the fatigue crack growth behavior in the materials of three different zones, the weld metal (WM), heat affected zone (HAZ), and base metal (BM), experimental fatigue crack growth tests for each of five specimens were performed on ASTM standard compact tension (CT) specimens under constant amplitude cyclic loading. Special focus was placed on the fatigued facture surfaces. As a result, a different behavior was observed at the macro-level, depending on the type of material property: BM, HAZ, or WM. The variability in the fatigue crack growth rate for WM was higher than that of BM and HAZ.

FSW 용접한 Al 7075-T651 용접재의 피로균열전파의 실험적 고찰

손혜정(Hye-Jeong Sohn),김치옥(Chi-Ok Kim),김선진(Seon-Jin Kim) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

The experimental investigation focuses on statistical variability of fatigue crack growth rate in friction stir welded Al 7075-T651 aluminum alloy on the three different zones, base meta (BM)l, weld metal (WM) and heat affected zone (HAZ). Friction stir welding is a new solid state joining method offering several advantages. The objective of this work is to investigate the fatigue crack growth rate behavior of FSWed 7075-T651 Al alloy under optimal FSW conditions. Fatigue crack growth tests were carried out on compact tension specimens (CT) under constant stress intensity factor range control according to ASTM standard. FCGR experiments were conducted at an Ratio of 0.1 and sinusoidal frequency of 10Hz with the three different zones specimens at constant stress intensity factor range 8, 11.5 and 15 MPa(m)1/2. The variability of fatigue crack growth rate showed strong dependency on three different zones WM, HAZ and BM.

다층 플럭스코아드아크 용접한 API 2W Gr. 50 강재의 피로균열전파율의 변동성 고찰

손혜정(Hye-Jeong Sohn),김선진(Seon-Jin Kim) 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5

Most of the components of marine and offshore structures are subjected to cyclic loading during their service time due to action of seawater waves and the sea environment in general. Fatigue failures in these structures can take place at sites of high stress concentraction that can be classified into two major categories, that is, base material and weld jaints. However, tt is well known that a considerable amount of scatter is showen in experimental results relating to fatigue crack growth even under identical and constant amplitude cyclic loading conditions. And also, it is well known that the Flux Cored Arc Welding(FCAW) is a common practice to join the thick plate such as structural members of large scale offshore structures and very larger container ships. The objective of this study is to investigate the variability of fatigae crack growth arte (FCGR) for the FCAWed API 2W Gr. 50 steel weldment typically applied for offshore structures. In order to investigate clearly the variability of fatigue crack growth rate for the materials of three different zones WM, HAZ and BM, experimental fatigue crack growth tests for each five specimens were performed on ASTM standard compact tension (CT) specimens under constant amplitude cyclic loading. It was showen that the variability of FCGR for WM specimen was higher then those of HAZ and BM, espacially in low driving force regio, and the probability distribution of FCGR was followed well Weibull distribution.

플럭스코아드아크 용접된 API 2W 강의 표준 CT 시험편 노치에서의 피로균열 발생 및 전파

손혜정(Hye Jeong Sohn),손상훈(Sang Hoon Sohn),정천영(Cheon Young Jeong),김선진(Seon Jin Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5

다층 플럭스코아드아크 용접한 API 2W Gr. 50 강재의 피로균열전파율의 변동성 고찰

손혜정(Hye-Jeong Sohn),김선진(Seon-Jin Kim) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5

Most of the components of marine and offshore structures are subjected to cyclic loading during their service time due to action of seawater waves and the sea environment in general. Fatigue failures in these structures can take place at sites of high stress concentration that can be classified into two major categories, that is, base material and weld joints. However, tt is well known that a considerable amount of scatter is shown in experimental results relating to fatigue crack growth even under identical and constant amplitude cyclic loading conditions. And also, it is well known that the Flux Cored Arc Welding (FCAW) is a common practice to join the thick plate such as structural members of large scale offshore structures and very larger container ships. The objective of this study is to investigate the variability of fatigue crack growth arte (FCGR) for the FCAWed API 2W Gr. 50 steel weldment typically applied for offshore structures. In order to investigate clearly the variability of fatigue crack growth rate for the materials of three different zones WM, HAZ and BM, experimental fatigue crack growth tests for each five specimens were performed on ASTM standard compact tension (CT) specimens under constant amplitude cyclic loading. It was shown that the variability of FCGR for WM specimen was higher than those of HAZ and BM, especially in low driving force region, and the probability distribution of FCGR was followed well Weibull distribution.

7075-T651 알루미늄 판재의 마찰교반용접과 피로균열전파 특성

김치옥(Chi Ok Kim),손혜정(Hye Jeong Sohn),김선진(Seon Jin Kim) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5

7075-T651 알루미늄 판재의 마찰교반용접과 피로균열전파 특성

김치옥(Chi Ok Kim),손혜정(Hye Jeong Sohn),김선진(Seon Jin Kim) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.10

마찰교반용접은 일반적인 용접법에 비하여 기계적 성질, 용접결함의 감소, 재료 절감 그리고 짧은 생산시간과 같은 장점 때문에 제작공정에 광범위하게 사용되고 있다. 본 연구의 목적은 이전의 실험 결과를 이용하여 마찰교반용접의 최적 조건을 검토하고 최적의 마찰용접조건에서 접합된 7075-T651 알루미늄 판재의 3가지 다른 영역, 즉 용접재, 열영향부재 그리고 모재에 대한 피로균열전파의 거동을 고찰하는 것이다. 최적의 마찰교반용접조건은 회전속도 800rpm, 이송속도 0.5mm/sec로 결정되었으며, 최적의 마찰교반용접에서 용접된 시험편에 대한 피로균열전파율은 3가지 영역의 재질, 즉 용접재, 열영향부재, 모재와 균열의 구동력에 크게 의존함을 보였다. Friction stir welding (FSW) method has extensively been used in manufacturing methods because of the several advantages over conventional welding methods, such as better mechanical properties, reduced occurrence of joining defects, high material saving, and low production time, etc. The aim of this paper is to review the optimal FSW conditions using the previous experimental results and is to investigate the fatigue crack growth rate in three different zones, WM, HAZ and BM for FSWed Al7075-T651 aluminum plates. As far as our experiments are concerned, the optimal conditions are obtained as rotation speed, 800rpm and travelling speed, 0.5mm/sec. The fatigue crack growth rate showed strong dependency on three different zones WM, HAZ and BM, and crack driving force.

마찰교반용접된 7075-T651 알루미늄 판재의 피로균열전파의 불규칙성

김선진(Seon Jin Kim),정의한(Yeui Han Jeong),손혜정(Hye Jeong Sohn),정원택(Won Taek Jung) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

The process of fatigue crack growth is generally random nature, due to many sources of variability, such as external loading, material properties and geometry conditions. Therefore it is important to investigate the statistical variability of fatigue crack growth in order to develop the methodology for stochastic fatigue crack growth life prediction. This paper is concerned with the statistical investigation of fatigue crack growth process for the FSWed 7075-T651 aluminum alloy. In this study, fatigue crack growth tests were conducted on 5 specimens of the FSWed 7075-T651 aluminum alloy under constant stress intensity factor range control, especially base metal, heat affected zones and weld metal specimens.