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정용현,이은석,박순영,양창환,정진택,Chung, Yong-hyun,Lee, Eun-seok,Park, Soon-young,Yang, Chang-hwan,Jung, Jin-taeg 항공우주시스템공학회 2009 항공우주시스템공학회지 Vol.3 No.2
The structural analysis of liquid rocket engine was performed in the case of sinusoidal vibration load to verify structural safety. The finite element model is composed with main liquid rocket engine components, combustion chamber, turbopump, gas-generator, pyro-starter, main pipes, main valve, heat-exchanger, gimbal-mount and brackets. Natural vibration mode analysis and structural analysis for sinusoidal vibration load were performed. The natural mode frequency of liquid rocket engine is twice than that of launch vehicle. In the case of stress result of sinusoidal vibration load, the part of maximum stress has 1.4 margin, so the engine structure is safe for sinusoidal vibration load.
방위산업의 시장구조 결정요인이 기술혁신과 시장지배에 미치는 영향
정용현,Chung, Young-Hyun 대전대학교 군사연구원 2007 군사학연구 Vol.5 No.-
This study examines the relationship of the industry-specific factors that effect innovation of manufacturing technology and the market share within the defense industry. Since the establishment of the basic defense industry framework in 1973, there were numerous interactions of the industry-specific factors of the defense industry structure with the technological innovation and market organization of the defense industry. During last three decades, the domestic defense industry has achieved the considerable level but the framework of the basic system has not developed much in areas of the military science and the defense manufacturing technology. Industry-specific factors were formed in the process and appeared in a variety of behavioral characteristics as subsystems. Currently, there IS a growing trend where the management of defense industry is gradually deteriorating due to limitation of the domestic industry-specific factor (e.g. defense technologies, amount of demand, etc.). If there is a prominent imbalance of the industry-specific factors. it can trigger the potential problem of conflict, lack of cooperation and control, slowing the growth of the manufacturing technology thereby diminishing the market and deteriorating the defense supply/demand relationship. In a research conducted by Joe S. Bain, Bain analyzed the relationship of the traditional industrial organization where industry-specific factor(S) not only impacts the conductor(C). And, conductor(C) influences the shaping of the performance(P) of relationship of the traditional industrial organization. Consequently, the researcher has identified the demand monopoly, barriers to entry, and market competition with comparison of defense industry issues. These defense issues were three industry-specific factors identified, which are 1) The demand monopoly and The entry barriers to new market competition, 2) the industrial technical factor to a production technical competitiveness and a market sharing competitiveness, 3) the probability factor to revolution for military affairs(RMA) and a R&D production. According to baseline with these factors, the following research model is established from the special companies group(Group A), the systematization companies group(Group B), and the general companies group(Group 0. The hypothesis is that if there are more industry-specific factors, then there will be more relationships of defense industry relation statutes. This research is an empirical study on the relationship that the industry specific factors effects the innovation of manufacturing technology and the shaping of the market in the defense industry. Moreover, the existing models to evaluate the industry specific factors of the defense industry IS much to be desired with the controlled statistical analysis of the result. It is vital to study on current situation with suggesting alternative strategy to the efficient strategy. The descriptive analysis approach analysis is conducted with SPSSWIN to conduct reliability test, factor analysis, correlation analysis, cross-tabulation analysis, one-way ANOVA, and multiple regression analysis. However, there were some limitations of the survey such as the rigidity of concept about the technical factors and various market management factors. The wishes is that the decision-maker could be utilized these defence industrial factors to formulate efficient defence policy and strategy in the future.
곽승준(Seung Jun Kwack),김순선(Soon Sun Kim),최요우(Yo Woo Choi),이규식(Gyu Seek Rhee),손경희(Kyung Hee Sohn),이이다(Rhee Da Lee),채수영(Soo Young Chae),정용현(Yong-Hyun Chung1),유일재(Il Je Yu1),박귀례(Kui Lea Park) 한국독성학회 2004 Toxicological Research Vol.20 No.2
3-Monochloro-1,2-propanediol(3-MCPD) is a toxic compound, often present in different foods containing acid hydrolyzed(AH) protein, like seasonings and savory food products. The purpose of the present study was to investigate the effects of 3-MCPD on male fertility, sperm and testosterone secretion. In vivo male fertility test was performed for observing the adverse effects of 3-MCPD on the function of male reproductive system and pregnancy outcome. 0.01, 0.05, 0.25, 1 and 5 mg/kg b.w. of 3-MCPD was given daily by gavage to groups of 15 adult male SD rats for 4 weeks. At the end of pre-treatment period, males were mated overnight with normal females. Following morning, males demonstrating successful induction of pregnancy were sacrificed on that day to assess sperm parameters and histopathology of reproductive organs. The resulting pregnant females were sacrificed on day 20 of gestation to evaluate pregnancy outcome. As a result, four-week paternal administration with 3-MCPD resulted in adverse effects on male fertility and pregnancy outcome without remarkable histopathological changes in testes and epididymides; sperm motility, copulation index and fertility index were markedly decreased in the treated group and numbers of live fetuses showed steep dose-response curves. Also, spermatogenesis was investigated in this experiment. However, no<br/> effect was observed on production of sperm in testes treated with 3-MCPD for 4 weeks. Hormone assay was performed for observing the effects of 3-MCPD on testosterone and luteinizing hormone (LH) in blood and testes of male SD rats and cultured primary Leydig cell. In result, significant changes of related hormones did not observed by treatment of 3-MCPD. These results indicated that paternal treatment with 3-MCPD induced spermatotoxic effect, which caused an antifertility on male.
김영목(Young-Mog KIM),이명숙(Myung-Suk LEE),정용현(Yong-Hyun CHUNG) 한국수산해양교육학회 2013 水産海洋敎育硏究 Vol.25 No.4
Water quality has been considered to be one of sanitation standard operating procedures (SSOP) for hazard analysis critical control points (HACCP) application in aquaculture farms. This study was conducted to evaluate a hazard caused by water used in aquaculture farm of rainbow trout. The water quality was analyzed to investigate both physiochemical and bacteriological level in water samples collected from aquaculture farm of rainbow trout, Oncorhynchus mykiss. No significant difference were observed on water temperature and pH from season to season. However, the levels of dissolved oxygen were decreased as the outside temperature was increased, even if the levels were adequate for aquaculture. Also, other physiochemical analysis including biochemical oxygen demand (BOD), chemical oxygen demand (COD) and suspended solid (SS) revealed that the waters for aquaculture analyzed in this study was suitable for rainbow trout aquaculture. The bacterial analyses were also revealed that the waters for aquaculture were met to both coliform group (<18 MPN/100mL) and viable cell count (<100 CFU/mL). However, some of waste waters from aquaculture farms showed higher levels of BOD and COD than those of waste water standard (<2 ppm), suggesting that regular cleaning of fish tank and precipitation tank is needed.
양식산 무지개송어에서의 항생제와 말라카이트 그린 잔류량 조사
김영목(Young-Mog KIM),이명숙(Myung-Suk LEE),정용현(Yong-Hyun CHUNG) 한국수산해양교육학회 2013 水産海洋敎育硏究 Vol.25 No.4
Products from aquaculture have sometimes been focused on the problems caused by the contamination of chemical agents as the use of chemical agents in aquaculture has been annually increased. The risk of contamination of products by chemical agents is greater in freshwater than in seawater. In order to evaluate the food safety of a fish grown in freshwater, we investigated the residues of antibiotics (tetracycline, oxolinic acid and ciplofloxacin) and malachite green in cultured rainbow trout, Oncorhynchus mykiss. Malachite green, which was prohibited in the application of aquaculture, was not detected in samples tested in this study. The residual content of tetracycline was determined to be less than the permissible amount, <0.2 mg/kg. The contents of ciplofloxacin was also less than the permissible amount, <0.1 ㎎/㎏. However, in case of oxolinic acid, one of samples was only exhibited higher content than the permissible amount (<0.1 ㎎/㎏). The results obtained in this study suggested that the control and regulation of chemical agents such as antibiotics was important to maintain a safe and worry-free seafood supply.
F344 랫드를 이용한 이황화메틸의 아급성 흡입독성연구
김현영,이성배,한정희,정용현,김형진,신진영,신동호,김종춘,이용묵,Kim Hyeon-Yeong,Lee Sung-Bae,Han Jung-Hee,Chung Yong-Hyun,Kim Hyoung-Chin,Shin Jin-Young,Shin Dong-Ho,Kim Jong-Choon,Lee Young-Mook 한국생명과학회 2005 생명과학회지 Vol.15 No.1
이황화메틸의 반복 흡입노출에 의한 아급성 독성 잠재력을 평가하기 위해 암수 랫드에게 0, 5, 25 및 125 ppm용량으로 21일간 반복 흡입노출하고, 일반증상과 체중, 사료섭취 량, 혈액치, 혈청생화학치 및 부검소견을 관찰하였다. 시험결과, 랫드에게 이황화메틸을 3주간 반복 흡입노출하면 125 ppm의 농도에서 체중증가의 억제와 사료섭취 량의 감소를 유발하나, 혈액 및 혈청생화학치에는 어떠한 이상도 유발하지 않는 것으로 나타났다. 본 시험 조건 하에서 이황화메틸의 표적 장기는 관찰되지 않았으며, 무해용량은 암수 모두 25 ppm으로 사료된다. The purpose of this study was to investigate the potential subacute toxicity of dimethyl disulfide by 3 weeks inhalation in F344 rats. The test article, dimethyl disulfide was exposed by inhalation to male and female rats at dose levels of 0, 5, 25, or 125 ppm/6 hrs/ day for 3 weeks. Five rats/ sex/ group were sacrificed on day 4 after the initiation of treatment, while 5 rats/ sex/ group were sacrificed at the end of treatment period. During the test period, clinical signs, mortality, body weights, food consumption, hematology, serum biochemistry, and gross findings were examined. Slight decreases in body weight gain were noted in both sexes of the highest dose group in a dose dependent manner but were only statistically different from the control animals in males of the group. A slight non-significant reduction in food consumption were also noted in the both sexes of the highest dose group. There were no adverse effects on mortality, clinical signs, hematology, serum biochemistry, and necropsy findings at any dose tested. Based on these results, it was concluded that the 3 weeks repeated dose of dimethyl disulfide by inhalation resulted in suppressed body weight gain and decreased food consumption at 125 ppm of both sexes. In the present experimental conditions, the target organ was not determined in rats. The noobserved-adverse-effect level (NOAEL) was considered to be 25 ppm/6 hrs/day for both sexes.