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.

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

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.

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.

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.

Tribological Properties and Friction Coefficient Prediction Model of 200μm Surfaces Micro-Textured on AISI 4140 in Soybean Crusher

최원식,프라타마 판두 산디,수페노 데스티아니,변재영,이은숙,우지희,양지웅,키프 디마스 하리스 신,크리스타 마이난다 브리기타,오케추쿠 나에메카 니콜라스,이강삼,Choi, Wonsik,Pratama, Pandu Sandi,Supeno, Destiani,Byun, Jaeyoung,Lee, Ensuk,Woo, Jihee,Yang, Jiung,Keefe, Dimas The Korean Society of Industry Convergence 2018 한국산업융합학회 논문집 Vol.21 No.5

In this research, the effect of normal load, sliding velocity, and texture density on thefriction coefficient of surfaces micro-textured on AISI 4140 under paraffin oil lubrication were investigated. The predicted tribological behavior by numerical calculation can be serves as guidance for the designer during the machine development stage. Therefore, in this research friction coefficient prediction model based on response surface methodology (RSM), support vector machine (SVM), and artificial neural network (ANN) were developed. The experimental result shows that the variation of load, speed and texture density were influence the friction coefficient. The RSM, ANN and SVM model was successfully developed based on the experimental data. The ANN model can effectively predict the tribological characteristics of micro-textured AISI 4140 in paraffin oil lubrication condition compare to RSM and SVM.

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.

근대계몽기 문예운동의 시각 ; 1910 년대 친일문학과 근대성 - 최찬식 (崔瓚植)

최원식(Won Shik Choi) 민족문학사학회·민족문학사연구소 1999 민족문학사연구 Vol.14 No.-

Choi Chan-sik(1881∼1951), one of the major writers of 1910`s, succeeded Lee In-jik(1862∼1917) who as a pro-japanese had played an active part in politics and literature in the period of patriotic enlightment(1905∼10). Unlike Lee who was subjectively pursued how to adapt himself to new colonial circumstances, Choi was objectively situated in the colonial life and was to find out modernity in the new way. In his work, through the simulation of various marriages, Choi experimented the making of the colonial modern based on the disintegration of traditional society. But modernity of his literature was limited to surface level because of the lack of tension toward Captial. So, after the brief heyday, he and his literature fell to the ground abruptly

후기수용모델(PAM)의 확장모델을 통한 외식기업 비대면 서비스 사용자 특성이 지속적 이용의도에 미치는 영향

최원식(Choi, Won-Sik) 한국외식경영학회 2020 외식경영연구 Vol.23 No.5

본 연구에서는 후기수용모델의 확장모형을 통한 외식기업 비대면 서비스를 이용한 사용자 특성이 인지적 몰입과 지각된 유용성이 지속적인 이용 의도에 미치는 영향 관계를 규명하고자 하였다. 실증분석은 최근 3개월 이내에 서울, 경기 지역에 거주하고, 외식기업의 비대면 서비스 경험이 있는 20대 이상의 소비자를 대상으로 설문 조사를 실시하여 총 232부를 통계 분석자료로 사용하였다. 본 연구의 분석결과는 비대면 서비스 사용자 특성의 하위요인인 자기효능감, 혁신성, 적합성은 지각된 유용성과 인지된 몰입에 매우 중요한 선행요인으로 밝혀졌으며, 지각된 유용성과 인지된 몰입은 지속적 이용 의도에 직접적인 영향을 미친다는 결과를 확인하였다. This study, we will investigate the relationship between the effects of user characteristics to cognitive immersion and perceived usefulness on continuous use intention by using non-face-to-face service of food-service through the expansion model of the late acceptance model. The empirical analysis conducted a questionnaire survey on consumers in their 20s and older who lived in Seoul and Gyeonggi Province and had no experience in serving food-service, and used a total of 232 copies as statistical analysis data. The analysis results of this study confirmed the results that self-effectiveness, innovation, and adaptability, which are subordinate factors of non-face-to-face service user characteristics, are very important prior factors for perceived usefulness and recognized immersion, and that perceived usefulness and recognized immersion have a direct impact on sustainability.

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.