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실란 처리돈 실리카 및 절단 유리섬유에 의한 폴리에스테르 수지의 인장강도 향상
이전규 ( Jeon Kyu Lee ),김시영 ( Si Young Kim ),주창식 ( Chang Sik Ju ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.1
선박용 부품에 적용할 수 있는 고분자 소재를 개발하기 위한 연구의 일환으로, 폴리에스테르 수지의 인장강도에 미치는 실리카와 절단 유리섬유의 영향을 조사하였다. 실리카와 절단 유리섬유의 첨가량 및 표면 개질에 사용된 커플링제의 농도를 변화시키면서 실험을 수행하였다. 표면 개질을 수행하지 않은 경우, 유리섬유의 첨가량이 증가하면 인장강도가 증가하였으나, 실리카는 첨가량이 증가할수록 인장강도가 감소하였다. 커플링제를 사용하여 첨가제의 표면을 개질하면 인장강도에 긍정적인 효과를 나타내었으며, 개질된 실리카와 절단 유리섬유를 혼합 첨가하면 인장강도의 증가에 상승효과를 나타내는 것을 알 수 있었다.
TTA와 TOPO를 이용한 수용액 중의 리튬이온 용매추출
주창식 ( Chang Sik Ju ),이전규 ( Jeon Kyu Lee ),정상구 ( Sang Gu Jeong ),구수진 ( Su Jin Koo ),김시영SiYoungKim 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.1
For the purpose of development of the extraction process of lithium ion from concentrated water eliminated from desalination process, an experimental research on the solvent extraction of lithium ion from aqueous solutions was performed. The effects of operating parameters, such as concentration of extractant, ratio of extracting solution/aqueous solution, pH of aqueous solution, were examined. The effect of sodium chloride, the major component of sea water, was also examined. Lithium ion in aqueous solutions of pH=10.2~10.6 adjusted by ammonia solution was most effectively extracted by extracting solution composed of 0.02 M TTA and 0.04 M TOPO in kerosine. The addition of sodium chloride in lithium aqueous solution significantly interfered the extraction of lithium ion.
박고은 ( Go Eun Park ),이윤미 ( Yun Mi Lee ),이전규 ( Jun Gyu Lee ),전현선 ( Hyun Sun Jeon ) 한국치위생학회(구 한국치위생교육학회) 2015 한국치위생학회지 Vol.15 No.3
Objectives: The purpose of this study is to investigate third and forth year dental students’ perception towards dental hygienists as professionals. Methods: A self-reported questionnaire was completed by 602 dental college students in Korea after receiving the informed consent. Except incomplete answers, 217 data were analyzed. The questionnaire consisted of three questions of the general perception towards dental hygienists, four questions of the cooperation relationship to the dental hygienists, four questions of oral health education, five questions of preventive dental health care, five questions of dental treatment cooperation, and five questions of dental health care management. The data were analyzed using PASW Statistics 18.0(SPSS Inc., Chicago, IL, USA). Results: Most of the dental college students viewed the dental hygienists as professionals. However, they did not exactly know the professional job of dental hygienists within the current national medical services system and they often viewed the dental hygienists as a medical assistant. The dental college students thought that the key role of the dental hygienists is the dental assisting. Only a small fraction of the participants recognized oral health promotion, preventive cares, and hospital management as professional roles of dental hygienists. Conclusions : Dental college students’ perception towards dental hygienists as professionals needs to be improved. Understanding the job description of dental hygienists clearly is a crucial part of dental students’ learning process and future practice.
나석은 ( Seok En Na ),최환오 ( Hwan Oh Choi ),이전규 ( Jeon Kyu Lee ),김사영 ( Si Young Kim ),주창식 ( Chang Sik Ju ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.5
Stern tube bearing is a shaft device playing important roles to reduce the friction of axial rotation and to support the weight of shaft. However, because there is no domestic producer of stern tube bering, imported stern tube bearings have many practical problems including prices, delivery and after services. This is why stern tube bearing should be localization. For the purpose of development of polyurethane resin for stern tube bearings, the effect of additives on the hardness, tensile strength and elongation of the polyurethane resin were systematically investigated. For the preliminary researches, depending on the type of curing agent, MOCA type and non-MOCA type polyurethanes were synthesized. Preliminary researches concluded that MOCA type polyurethane resin has more excellent mechanical properties than non-MPCA type for stern tube bearings that Tensile strength and Hardness of non-MOCA type investigated 23 D, 4.3 Mpa. Therefore, MOCA type polyurethane was adapted as base resin of this research. Silica, calcium carbonate and graphite were selected as additives for the enhancement of mechanical properties of polyurethane resin. Effect of the type and the dosage of these additives on the hardness, tensile strength, elongation of the polyurethane resin were experimentally examined. However, addition of calcium carbonate and graphite showed only minor effect on the hardness of the resin. Polyurethane resin with silica showed relatively excellent hardness, tensile strength and improved elongation.
유재홍 ( J H Yoo ),심명용 ( M Y Shim ),이전규 ( J K Lee ),이영돈 ( Y D Lee ),주진호 ( J H Joo ) 강원대학교 농업생명과학연구원(구 농업과학연구소) 2015 강원 농업생명환경연구 Vol.27 No.3
Organic agriculture is holistic production management systems which promote and enhance agro ecosystem health, including biodiversity, biological cycles, and soil biological activity. The Codex guidelines have been prepared for the purpose of providing an agreed approach for the requirements which underpin production of the labelling and claims for, organically produced foods. These guidelines set out the principles of organic production at farm, preparation, storage, transport, labelling and marketing stages, and provides an indication of accepted permitted inputs for soil fertilizing and conditioning, plant pest and disease control and, food additives and processing aids. Any substances used in an organic farming system for soil fertilization and conditioning, pest and disease control should comply with the relevant national regulations. The permitted substances for organic agriculture according to Environmental friendly Agriculture Promotion Act in Korea are 43 substances for use in soil fertilizing and conditioning and 42 substances for plant pest and disease control.