Tribological Characteristics in $40{\mu}m$ Dimple Pattern for Hexagonal Array

최원식,채영훈,Choi, Won-Sik,Chae, Young-Hoon,Umehara, Noritsugu Korean Tribology Society 2009 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.17 No.5

본 연구에서는 pin-on-disk 마찰 시험기를 통하여 Hexagonal 배열 $40{\mu}m$ Dimple 패턴의 효과를 실험하였다. 마찰 실험은 미끄럼 속도가 $0.06{\sim}0.34m/s$로 하였으며 마찰하중은 $20{\sim}100\;N$의 범위로 하였고, Dimple의 밀도는 $10{\sim}25%$의 범위로 제작하여 실험을 행하였다. 일반적으로 속도가 증가하고 하중이 감소할수록 마찰계수는 감소하는 경향을 나타내었으며, Dimple에 의한 마찰저감 효과는 속도가 $0.14{\sim}0.26m/s$의 범위에서 나타났다. $40{\mu}m$ Hexagonal 배열 Dimple 패턴의 마찰 특성에서는 밀도가 12.5%에서 가장 좋은 경향을 나타내었다.

한국산 옻나무로부터 추출.분리한 생리활성 물질들의 항산화 효과 및 세포독성

최원식,김동길,이영행,김장억,이성은,Choi, Won-Sik,Kim, Dong-Kil,Lee, Young-Haeng,Kim, Jang-Eok,Lee, Sung-Eun 한국응용생명화학회 2002 한국농화학회지 Vol.45 No.3

한국산 옻나무의 메탄올추출물과 유기용매 분획의 항산화 효과를 조사하였다. 항산화 효과는 수소공여 억제능, 과산화지질 형성 억제능, xanthine oxidase저해 활성과 아질산염 소거능으로 측정한 결과, ethyl acetate 분획이 가장 뛰어난 효과를 나타내었다. 이 분획의 생리활성 물질을 분리하기 위하여, rotatory locular counter current chromatography(RLCCC), Sephadex LH-20 column chromatograpy와 HPLC등의 방법을 사용하여, 1,2,3-trihydroxybenzene, methyl 3,4,5-trihydroxybenzoat와 3,4,5-trihydroxybenzoic acid를 분리하였다. 이중 methyl 3,4,5-trihydroxybenzoate는 butylated hydroxyanisole(BHA)이나 butylated hydroxytoluene(BHT)보다도 강한 항산화 효과를 나타내었다. 그러나 세포독성 실험에서는 이들 물질들이 암세포주에 대하여 활성이 높지 않았다. 이상의 결과로 methyl 3,4,5-trihydroxybenzoate은 뛰어난 항산화 효과를 지닌 식품첨가물로서의 이용 가능성을 제시할 수 있다. Antioxidative activities of solvent fractions obtained from Korean Rhus vernicifera, being used in food industry and as a traditional medicine, were examined by the methods of DPPH scavenging activity, inhibitory effect on autooxidation of linoleic acid, nitrite scavenging activity and the inhibitory effect on xanthine oxidase activity. Ethyl acetate fraction showed potent antioxidative activities. Three compounds were isolated from the ethyl acetate fraction by rotatory locular counter current chromatography (RLCCC), Sephadex LH-20 column chromatography and HPLC. The isolated compounds were 1,2,3-trihydroxybezene, methyl 3,4,5-trihydroxybenzoate and 3,4,5-trihydroxybenzoic acid determined by GC/MS and, $^1H$ and $^{13}C$ NMR. Among the isolated compounds, methyl 3,4,5-trihydroxybenzoate showed the strongest antioxidative activity than artificial antioxidants, BHA and BHT in various methods. However, these isolated compounds did not show cytotoxicity effects on the human cancer cell lines. Therefore, we may suggest that methyl 3,4,5-trihydroxybenzoate can be used as a food additive possessing the potent antioxidative activity.

선박엔진의 Supply Unit용 SNCM420H의 절삭특성

최원식,성봉수,강창원,문희준,권주리,Choi, Won-Sik,Sung, Bong-Soo,Kang, Chang-Won,Mun, Hee-Joon,Kwon, Ju-Ri 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.5

SNCM420 steel is one of the cam shaft materials which are used in the supply unit for ship engine cam shaft. In this study the assessment of cutting behavior was conducted for the SNCM 420 steel and SM45C steel with various cutting conditions as depth of cut 0.5, 1.0, 1.5, 2.0mm and feed rate 0.1~0.3m/rev. The controlled chip was produced in feed rate 0.2, depth of cut 1.0 for SNCM420 and feed rate 0.2, depth of cut 2.0 for SM45C. There is no difference cutting force between SM45C and SNCM420 steels.

Coenzyme Qn 유도체들의 합성

최원식,어진용,남석우,김재훈,이영행,Choi, Won-Sik,Eo, Jin-Yong,Nam, Seok-Woo,Kim, Jae-Hoon,Lee, Young-Haeng 대한화학회 2007 대한화학회지 Vol.51 No.6

6${\beta}$-Bromopenicillanate로부터 6-(Carboxymethylthio) penicillanic Acid 유도체의 합성

최원식,이영행,이채호,Won-Sik Choi,Young-Haeng Lee,Chai-Ho Lee 대한화학회 1991 대한화학회지 Vol.35 No.5

6${\beta}$-bromopenicillanic acid(4a)와 p-nitrobenzylbromide, 3-bromophthalide, chloromethylpivalate 및 1-chlorodiethylcarbonate의 반응으로 6${\beta}$-bromopenicillanates(4b~4e)을 합성하였으며, 6${\beta}$-bromopenicillanic acid(4a)와 그의 ester(4b~4e)를 thioglycolic acid와 친핵성 치환반응시켜 새로운 $\beta$-lactam계 화합물인 6-(carboxymethylthio)penicillanic acid(5a)와 그의 ester(5b~5e)를 얻었다. Reaction of 6${\beta}$-bromopenicillanic acid(4a) with p-nitrobenzylbromide, 3-bromophthalide, chloromethylpivalate and 1-chlorodiethylcarbonate afforded 6${\beta}$-bromopenicillanates(4b~4e). New ${\beta}$-lactam compound, 6-(carboxymethylthio)penicillanic acid(5a) and the other esters(5b~5e) were prepared by nucleophilic substitution reaction of 6${\beta}$-bromopenicillanic acid(4a) and the other esters(4b~4e) with thioglycolic acid.

Friction Characteristics of CNx Coated Dimple Pattern with Hexagonal Array

최원식,Choi, Won-Sik,Umehara, Noritsugu Korean Tribology Society 2011 한국윤활학회지(윤활학회지) Vol.15 No.3

In this study, we examined the friction characteristics of a dimple pattern on a carbon nitride coating. The study was conducted with a hexagonal array 40 ${\mu}m$ dimple pattern on a steel bearing containing a CNx coating. The area density of the dimple patterns were varied between 5% and 25%, the speed was varied from 0.06-0.26 m/s, and the load was varied between 20-100N. In general, we found that as the velocity increased, the friction coefficient increased. Furthermore, the friction coefficient was lowest at a load of 40N. The friction coefficient of the non-coated specimen was 0.025-0.15; on the other hand, the friction coefficient of the coated specimen was 0.002-0.02. Thus, we determined that the coated materials could reduce the friction coefficient by a factor of 7.5.

환경전과정평가에 기반한 UV-LED 를 사용한 복합식 가습기에 관한 연구

최원식(Won-Sik Choi),박시현(Si-Hyun Park),이시왕(Si-Wang Lee),정영미(Young Mi Jung),이화조(Hwa Cho Yi) Korean Society for Precision Engineering 2012 한국정밀공학회지 Vol.29 No.9

3-[(4-카르복시-5-에틸티오이소티아졸-3-일)옥시메틸] 세파로스포린 유도체들의 합성 및 항균력에 관한 연구

최원식(Won Sik Choi),박의석(Eui Suk Park),박규종(Kyu Jong Park),이영행(Young Haeng Lee) 대한약학회 2000 약학회지 Vol.44 No.2

New cephalosporin antibiotics, 3-[(4-carboxy-5-ethylthioisothiazol-3-yl)oxymethyll-7-[(1H-tetra-zol-1-yl)acetamido]-3-cephem-4-carboxylic acid 2, 3-[(4-carboxy-5-ethylthioisothiazol-3-yl)oxymethyl]-7-[(2-aminothiazol-4-yl)acetamidol-3-cephem-4-carboxylic acid 3, 3-[(4-carboxy-5-ethylthioisothiazol-3-yl)-oxymethyl]-7-[5-(ethylthio-3-hydroxyisothiazol-4-yl)carboxamido]-3-cephem-4-carboxylic acid 4, 3-[(4-carboxy-5-ethylthioisothiazol-3-yl)oxymethyl]-7-[(Z)-2-(fur-2-yl)-2-(methoxyimino)acetamido]-3-cephem-4-carboxylic acid 5, 7-[(Z)-2-(2-aminothiazol-4-yl)-2-[(alkoxyimino)acetamido]-3-[(4-carboxy-5-ethylthioisothiazol-3-yl)oxymethyl]-3-cephem-4-carboxylic acid 6-8 were synthesized. Antibacterial activities and structure-activity relationships of these new cephalosporin derivatives were examined. Among them, 7-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxy-l-methylethoxyimino)acetamido]-3-[(4-carboxy-5-ethylthylthioisothiazol-3-yl)oxymethyl]-3-cephem-4-carboxylic acid 7 exhibited good antibacterial activities compared to cefotaxime and ceftriaxone.

공공시설 자산관리 정보화 방안

최원식(Won-Sik Choi),나혜숙(Hei-Suk Nah),서명배(Myoung-Bae Seo),정성윤(Seong-Yun Jeong),임종태(Jong-Tae Lim) 한국콘텐츠학회 2010 한국콘텐츠학회논문지 Vol.10 No.11

사회기반시설이 노후화됨에 따라 현행 시설물 유지관리를 넘어 예산을 절약하고 시설물의 가치를 높이기 위해 공공시설에 자산관리를 도입해야 한다는 요구가 증대되고 있다. 공공시설 자산관리는 이러한 요구에 대응하기 위한 새로운 시설물 유지보수 개념으로 기존의 시설물 유지관리업무를 통해 축적된 데이터를 분석하고 생애주기분석, 리스크관리 등의 의사결정 방법을 활용하여 최적화된 유지관리계획을 수립하고 실행하는 것이다. 자산관리의 정보화 방안을 도출하기 위해 자산관리 업무를 조사하고, 뉴질랜드의 IIMM의 내용과 미국의 FHWA의 업무정의 그리고 국내의 대표적 유지관리시스템을 분석하였다. 또한 현행 시설물 유지관리 조직간의 역할을 조사하고, 자산관리 조직과 업무간의 관계를 분석하였다. 마지막으로 자산관리에 필요한 정보와 기존 유지관리시스템이 포함하고 있는 정보를 자산관리 업무와 비교분석하였다. 본 논문에서는 공공시설 자산관리 정보화 방안으로 첫째, 시설물 유지관리시스템에 있는 기능을 중복해서 개발하지 않고 자산관리 핵심업무만을 구현하며 둘째, 시스템의 구조를 계층으로 분할하고 셋째, 자산관리시스템과 기존 시설물 유지관리시스템들간을 연동하여 정보를 공유하는 방안을 제시하였다. With the social infrastructure being deteriorated, there is a growing need to introduce the asset management to social infrastructure management in order to increase their value and save budget. Social infrastructure asset management is a new concept of facility management in response to these demands. It is defined as a procedure for collecting and analysing facility maintenance data and for making and practicing an economically optimized management plan. Detailed survey work of asset management business is analyzed in order to derive a strategy for asset management information. The contents of IIMM of New Zealand and the asset management definition of the FHWA of the United States, and representative facility management systems of Korea are analysed. The role between organizations and the relationship between business and organization were analyzed. Information required for asset management and for existing facility management systems is compared with business of asset management. In this thesis, three development strategies are suggested. The first one is to develop core business of asset management while excluding duplicated development. The second one is to divide system's structure into three layers. And the last one is to share information by interfacing asset management systems with existing facility management systems.

IPA 기법을 활용한 한우 선택속성에 관한 연구 : 연령대와 소득 유형에 따른 차이 분석

최원식(Choi, Won-Sik),이단(Li, Dan),김영중(Kim, Young-Joong) 한국외식경영학회 2021 외식경영연구 Vol.24 No.2

본 연구에서는 한우를 구매한 소비자의 연령대와 소득 유형을 분류하고, 소비자 유형에 따라 한우 선택속성의 중요도-만족도를 인지하는 데 어떠한 차이가 있는지를 분석하고자 하였다. 본 연구를 위해 한우를 구매한 경험이 있는 대구, 경북지역에 거주하는 20세 이상의 소비자를 대상으로 총 299부를 실증분석에 사용하였다. 분석 결과, 첫째, 한우 선택속성의 중요도와 만족도 분석결과, 맛과 품질 속성들이 가장 중요하다고 생각하고 있는 것으로 나타났다. 둘째, IPA를 활용한 한우 선택속성은 소비자가 가장 중요하게 여기는 것으로 맛, 품질, 안전성, 청결 및 위생, 건강 등의 속성으로 나타났다. 셋째, 연령대에 따른 한우 선택속성은 맛, 품질, 위생, 안전성 등이 중요도와 만족도가 가장 높게 인지된 속성으로 나타났다. 넷째, 소득에 따른 한우 선택속성은 맛, 품질 등은 중요도와 만족도가 가장 높게 인지된 속성으로 나타났다. This study was to classify the age groups and income types of consumers who purchased Korean beef and to analyze what differences exist in recognizing the importance-satisfaction of the selection attribute of Korean beef according to consumer types. To achieve the purpose of this study, a survey was conducted on consumers over 20 years of age living in Daegu and Gyeongbuk who have purchased Korean beef and a total of 299 were used for empirical analysis. The analysis results, First, the importance and satisfaction of Korean beef selection attributes, it was found that taste and quality attributes were considered the most important. Second, as for the selection attribute of Korean beef according to age, taste, quality, hygiene and safety were the attributes that were recognized as the most important and satisfaction. Third, as for the selection attribute of Korean beef according to income, taste and quality were the attributes that were recognized as the most important and satisfaction.