탄화물 입자 강화 7075 Al 합금 기지 복합재료의 미끄럼마멸 특성에 미치는 기지 합금 변형의 영향

강석하,강신철,김용석 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.4

Sliding wear behavior of 7075 Al alloy matrix composites was investigated. Reinforcements of the composite were SiC, TiC, and B_(4)C particles with various size and volume fractions. Sliding wear tests were carried out in an ambient atmosphere using a pin-on-disk wear tester with various loads of 5N-150N against a bearing steel ball counterpart. The composites showed higher wear resistance than the monolithic matrix alloy. Sliding wear of the composites proceeded by a grinding mechanism at low loads and by a delamination of a deformed layer at high loads. Wear resistance of the composites increased with the size and volume fraction of the reinforcements, and the increase was more significant at high applied loads. Deformation of the matrix was found to control the wear at high loads. The effect of heat treatment and reinforcement variation including size, volume fraction and species on the wear was discussed in connectin with the deformation of the matrix. (Received September 19, 2003)

(+)-Eldanolide의 합성에 관한 연구

강석구,이동하,이정민 성균관대학교 1990 論文集 Vol.41 No.2

출발물질로 D-타타르산 사용하여 (+)-eldanolide의 합성을 연구하였다. 이 합성에서의 중요반응은 온도를 -78℃→0℃로 하여 lithium diisopropylamide 사용하여 (2R, 3R)-1-chloro-2,3-isopropylidenedioxy-6-methy-5-heptene을 탈수소-제거반응시켜 중요한 반응 중간체인 (3R)-6-methyl-heptyn-5-en-3-ol을 합성하는 것이다. Synthetic approach to (+)-eldanolide from D-tartaric acid as starting material is described. They key reaction is the deprotonation-elemination reaction of (2R, 3R)-1-chloro-2, 3-isopropylidenedioxy-6-methyl-5-heptene with lithium diisopropylamide at -78℃→℃ and the key intermediate is (3R)-6-methyl-heptyn-5-en-3-ol.

탄화물 입자 강화 7075 Al 합금 기지 복합재료의 미끄럼마멸 특성 연구

강석하,박형철,강신철,김용석 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-

Effects of the type and volume fraction of carbide-particle-reinforcements on dry sliding wear behavior of 7075 Al alloy matrix composites were investigated. SiC, TiC and B₄C reinforced 7075 Al alloy matrix composites were manufactured by a pressureless infiltration technique and wear tested. Wear tests were carried out using a pin-on-disk wear tester with varying loads of 3N-160N at a constant sliding velocity of 0.2m/s. AISI 52100 bearing steel ball was a counterpart of the composites. Wear resistance of the composites was always higher than that of the monolithic alloy except the TiC reinforced 7075 Al matrix composite. The resistance increased with the increase of volume fraction of the reinforcing particles. Among the composites, the TiC reinforced composite had the lowest wear resistance and the B4C reinforced composite showed the highest wear resistance.

수목추출물의 생리활성에 관한 연구(Ⅸ) : 아까시나무 심재의 항산화활성 물질 Antioxidative Compounds from Heartwood of Robinia pseudo-acacia

최돈하,이학주,이성숙,김윤근,강하영 한국목재공학회 2002 목재공학 Vol.30 No.4

항산화활성이 우수한 아까시나무 심재 에탄올 조추출물로부터 항산화물질을 탐색할 목적으로 4종의 화합물을 단리하였으며, MS, NMR 등의 분광학적 방법에 의해 그 화학적 구조를 3-β-stigmast-5-en-3-ol(daucosterol)를 비롯하여 스틸베노이드 화합물인 3,3' ,4' ,5-tetrahydroxystilbene과 후라보노이드인 3,3' ,4' ,5' ,7-pentahydroxyflavone(robinetin) 및 3,3' ,4' ,7-tetrahydroxyflavanone(fustin)으로 각각 동정하였다. 단리된 화합물의 프리라디칼 소거능을 측정하여 항산화활성을 검정한 결과, 페놀성 수산기가 5개인 3,3' ,4' ,5' ,7-pentahydroxyflavone은 천연항산화제 및 합성항산화제보다 높은 항산화활성을 나타내어 단리화합물 중 가장 항산화활성이 높은 것으로 나타났다. 또한, 페놀성 수산기가 4개인 3,3' ,4' ,5-tetrahydroxystilbene과 3,3' ,4' ,7-tetrahydroxyflavanone도 천연항산화제인 α-tocopherol보다 높은 항산화활성을 나타내었으나 3-β-stigmast-5-en-3-ol은 항산화활성이 없는 것으로 나타나 프리라디칼 소거능에 의한 항산화활성은 화합물의 페놀성 수산기수에 크게 좌우되는 것으로 판단되었다. 이상의 결과 아까시나무의 높은 항산화활성은 3,3' ,4' ,5' ,7-pentahydroxyflavone. 3,3' ,4' ,5-tetrahydroxystilbene 및 3,3' ,4' ,7-tetrahydroxyflavanone에 기인하는 것으로 사료되었다. Antimicrobial and antioxidative activities on heartwood extractives of domestic species were investigated to develop a natural fungicide or preservative. One steroid, stilbene derivatives and two flavonoids were isolated from heartwood of Robinia pseudo-acacia which has been selected due to its high antioxidative activity among the tested species. The structures were determinded as : 3-β-stigmast-5-en-3-ol(daucosterol), 3,3',4,5-tetrahydroxystilbene, 3,3',4',5',7-pentahydroxyflavone(robinetin) and 3,3',4',7-tetrahydroxyflavanone(fustin) respectively on the basis of spectroscopic data and chemical correlations. According to the results of free radical scavenging activity, 3,3',4',5',7-pentahydroxyflavone was evaluated as the highest antioxidative compound among the four compounds and showed higher radical scavenging activity than those of α-tocopherol and butylated hydroxytoluene(BHT), one of the strongest synthetic antioxidants. 3,3',4',5-Tetrahydroxystilbene and 3,3',4',7-tetrahydroxyflavanone showed higher antioxidative activities than that of α-tocopherol. However, 3-β-stigmast-5-en-3-ol did not show free radical scavenging activity. In this regard, it could inferred that high antioxidative activity of extractives of R. pseudo-acacia was derived from 3,3',4',5',7-pentahydroxyflavone, 3,3',4',5-tetrahydroxystilbene and 3,3',4',7-tetrahydroxyflavanone.

수목 정유의 생리활성화에 관한 연구(1) : 침엽수 잎 정유의 항균활성 Antimicrobial Activity of Essential Oils from Coniferous Needles

이성숙,강하영,최인규 한국목재공학회 2002 목재공학 Vol.30 No.1

대표적인 침엽수인 소나무, 잣나무, 편백, 화백의 잎 정유를 사용하여 수목 정유의 항균활성에 관하여 조사하였다. 항진균활성은 배지점적법을 이용하여 목재부후균인 Gliocladium virens, Tyromyces palustris, Trametes versicolor를, 비부후성 열화균인 Rhizopus stolonifer를, 수목병원균인 Phomopsis albobestita, Endothia nitschkeii, Melanconis juglandis에 대하여, 그리고 항세균활성은 paper disc법과 탁도측정법을 이용하여 그람양성균인 Staphylococcus aureus, Streptococcus faecalis, Bacillus subtilis 및 그람음성균인 Escherichia coli에 대하여 검정하였다. 그 결과 항진균활성은 편백이 가장 우수한 것으로 나타났으며 그 다음이 소나무와 잣나무로 목재부후균에 대해서는 소나무가 잣나무보다 높은 활성을, 수목병원균에 대해서는 잣나무가 소나무보다 높은 활성을 나타내었다. 그리고 화백 잎 정유가 가장 활성이 낮은 것으로 나타났다. 또한, 항세균활성은 항진균활성과 달리 소나무 잎 정유가 편백보다 높은 활성을 보였으며 그 다음이 잣나무 그리고 화백의 순이었다. 이러한 정유에 따른 항균 스펙트럼의 차이는 각 정유의 성분 변이와 이러한 성분들의 미생물에 대한 작용특이성에 기인하는 것으로 사료되었다. The essential oils were extracted from the needles of several softwood tree species, Pinus densiflora, Pinus koraiensis, Chamaecyparis obtusa and Chamaecyparis pisifera to investigate their biological activities. The antifungal activity by hyphal growth inhibition method was determined by three wood rot fungi, one mouldous fungi, and three tree pathogenic fungi and the antibacterial activity by paper disc method and turbidiometric method by three gram positive bacteria and one gram negative bacteria, Escherichia coli, were also tested. Antifungal activity was the best in the essential oil from C. obtusa, and the following was resulted in order of P. densiflora and P. koraiensis. The essential oil from P.densiflora showed higher antifungal activity against wood rot fungi than that from P. koraiensis, while the result was contrary against tree pathogenic fungi. However, the antibacterial activity was the best in the essential oil from P. densiflora, and the following was in order of C. obtusa and P. koraiensis. From these results, the variation of biological activity seemed to be due to the chemical composition of essential oils.

전류 비유 모델에 의한 초등학생의 전류 개념 변화 분석

유병길,강인석,김병철,남만희,박선희,소하연,윤희정,이영아,이하룡,전병문,정승호 부산교육대학교 과학교육연구소 2000 科學敎育硏究 Vol.25 No.-

There exists a major impediment to learning electricity which may illuminate why direct presentation of scientists' ideas is too aggressive a strategy. This impediment lies in thinking that electricity is used up and in envisaging the light bulb as a consumer. This view is based on a powerful idea which summarises much of our experience; it declares that 'things get used up', 'you cannot get something for nothing', and 'intuitive thinking'. To replace this view with scientific view, we made the analogy model. It is suggested that the analogy model is more effective in teaching electricity circuits than conventional teaching method.

베타락탐계 항생제 합성과 항균성

고옥현,강형룡,유진철,김경수,홍석순,김영수,황화영,하재천 조선대학교 약학연구소 1992 藥學硏究誌 Vol.14 No.1

7β[5-(Substituted) phenyl-2H-tetrazol-2-yl]acetamidocephalospranic acid, 7β-(5-Diphnenyl-methyl-2H-tetrazol-2-yl) acetamidocephalosporanic acid and 7β-[5-(Substituted)-4-phenyl-1.2.4-triazol2-yl]thioacetamidocephalosporanic acid were synthesized and tested in vitro antimicrobial activity. These compounds exhibited good antimicrobial activity against Gram-positive bacteria whereas most compounds showed decreased antimicrobial activity against Gram-negative bacteria

지역별 중학생들의 체격, 체력 및 비만에 관한 비교조사 연구 : 서울 강동구와 충남 아산시를 중심으로

윤규태,강석하 순천향대학교 기초과학연구소 2008 순천향자연과학연구 논문집 Vol.14 No.2

This research is to comparative study on the physique and the physical fitness and the obesity of the Regions that S middle school which is located in Seoul, which are 172 students(90 boys, 82 girls) and that 84 boys from A middle school, 74 girls from F middle school also located in Chungnam. totally 330 students. Then after we got the result we compared the result with the average of examination of the physical fitness for whole students reported by the Ministry of Education and Human Resour Development. Obtain the result follow: First, in the structure of physique, The Seoul area students appeared the Chungnam area students compared to 4.2cm height and 2.7kg weight highly. The Seoul area girls students who was higher 1.4cm and lower weight 0.6kg, than Chungnam area girl students. In the physical fitness, the average figures of boys in Chungnam are higher than the average figures of boys in Seoul in a standing long jump, a push-up, sit-ups, sit and reach. the average figures of girls in Chungnam was higher than the average figures of girls in Seoul in a standing long jump, fixed-arm hanging and a long distance race. Second, in the structure of physique fitness the height and for boys and girls studnts Seoul and Chungnam girl students are higher than the national average. Weight was appeared highly seoul area man and two area girls students than the national average. In the physical fitness the students in Seoul have under average in all items except push-ups. And boys in Chungnam have higher result than the national average in sit-ups and sit and reach. In two area girls students, there was appeared more lowly the national average than from all items. Third, in the degree of obesity, A Seoul area boy students was under weight(0.5%) and hi degree of obesity(1.6%) than Chungnam area boys. A Seoul area girl studnts was low of over weight(5.6%) and hi degree of obesity(1.8%) than a Chungnam area girls

强迫神經症의 精神治療에 對한 小考

鄭昌鎔,김상욱(?),姜錫憲,尹錫夏 大韓神經精神醫學會 1970 신경정신의학 Vol.9 No.1

1) From the authors' Psychotherapeutic experiences with obsessive neurotics Since 1964. they stressed the characteristic projection phenomena of inner feeling of dissatisfaction or disgust into alleged outer unfulfillment of performances in the repetitive and ritualistic activities of obsessive neurotics. 2) In the earlier phases of psychotherapy with obsessive neurotics, the authors' primary attention is focused on these projection phenomena with the aid of “logical dialogue”which is characterized by therapists' logical attacks at pseudological defensive operations of obsessive neurotics. 3) With these rather half-directed methods, the authors felt the psychotherapists could save much of unnecessary introductory plases of psychotherapy with obsessive neurotics.

The Effects of Fucoidan Extracts on $CCl_4$-Induced Liver Injury

Kang, Kum-Suk,Kim, In-Deok,Kwon, Ryun-Hee,Lee, Jin-Young,Kang, Jae-Seon,Ha, Bae-Jin 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.5

The aim of this study was to elucidate the antioxidant properties of fucoidan extracts (FE) against $CCl_4$-induced oxidative stress by monitoring the levels of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Female, Sparague-Dowley rats were administered with FE (100 mg/kg daily) for 14 days and $CCl_4$ on the 15'th day, 12 h before they were sacrificed. The levels of GOT, GPT, ALP and LDH in serum of rats, as well as the levels of MDA, SOD, CAT and GPx in total liver homogenate were analyzed. $CCl_4$-treatment was found to increase the levels of GOT, GPT, ALP, LDH and MDA, as well as decrease levels of SOD, CAT and GPx significantly. The pre-treatment of rats with FE, however, suppressed the increment of levels of GOT, GPT, ALP, LDH and MDA, as well as recovered the levels of SOD, CAT and GPx in CCl4-treated rats. Moreover there was a significant decrease in incidences of necrosis and cirrhosis in the liver tissue of FE-treated rats. These results implied that FE possessed antioxidant properties against $CCl_4$-induced oxidative stress.