http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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.
정용현,이은석,Chung, Yong-hyun,Lee, Eun-Seok 항공우주시스템공학회 2007 항공우주시스템공학회지 Vol.1 No.4
The process of Lay-out design and assembly for liquid rocket engine was presented and the Lay-out design for main components of liquid Rocket engine system was studied. Vertical direction is recommended in the case of turbopump's arrangement. If the length of pipe between gas-generator with turbopump's turbine is shorter, gas-generator is stable. The arrangements of main valves are recommended as near disposition to combustion chamber, because shut-down process time is shorter. Interference with launch vehicle and structural strength considering gimbal actuator's force and control performance is considered in the case of gimbal actuator's supporter design.
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.
배열형 섬광결정을 이용한 소형 감마카메라의 평행구멍형 조준기 최적화 연구
정용현,백철하,이승재,박진형,Chung, Yong-Hyun,Beak, Cheol-Ha,Lee, Seung-Jae,Park, Jin-Hyung 한국의학물리학회 2008 의학물리 Vol.19 No.4
이 연구의 목적은 몬테칼로 모사방법을 이용하여 배열형 CsI 섬광결정을 가진 소형 감마카메라의 평행구멍형 조준기를 최적화하고 조준기 부착시 발생할 수 있는 결합오차가 영상의 질에 미치는 영향을 평가하는 것이다. GATE 코드를 이용하여 육각형과 사각형 평행구멍형 조준기의 구멍크기에 따른 Tc-99m 점선원 영상의 민감도 및 공간분해능을 측정하고 최적화된 조준기를 바탕으로 조준기와 섬광체 사이에 2 mm 이내의 미세한 틈이 있을 경우에 대한 평판선원의 영상 균일도를 측정하였다. 동일 구멍크기에 대해 사각구멍형 조준기가 육각구멍형 조준기에 비해 민감도가 우수한 결과를 보였으며, 섬광결정과 사각구멍조준기의 크기를 1 대 4로 일치시켰을 때, 선원의 거리에 따른 공간분해능의 변화가 가장 적은 것을 알 수 있었다. 조준기와 검출기의 결합면 평행오차는 영상의 균일도와 민감도 모두를 선형적으로 감소시키는 경향을 보였다. 이 연구 결과는 배열형 섬광결정과 단일 섬광결정에 대해 조준기의 성능차이를 보이고, 영상의 균일도 및 민감도 저하의 원인이 조준기의 결합오차에서 기인할 수 있음을 증명함으로써, 핵의학 영상 화질 개선을 위한 새로운 접근법을 제시한다. The purpose of this study is to optimize a parallel-hole collimator for small gamma camera having the pixellated crystal array and evaluate the effect of crystal-collimator misalignment on the image quality using a simulation tool GATE (Geant4 Application for Tomographic Emission). The spatial resolution and sensitivity were measured for the various size of hexagonal-hole and matched square-hole collimators with a Tc-99m point source and the uniformity of flood image was estimated as a function of the angle between crystal array and collimator by misalignment. The results showed that the spatial resolution and sensitivity were greatly improved by using the matched collimator and the uniformity was reduced by crystal-collimator misalignment.
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.
한국산 백석면이 랫드의 폐 기능에 미치는 영향 평가 연구
정용현 ( Yong Hyun Chung ),강민구 ( Min Gu Kang ),한정희 ( Jeong Hee Han ) 한국산업보건학회 2014 한국산업보건학회지 Vol.24 No.2
Objectives: To evaluate the pulmonary toxicity of Korean Chrysotile(KC), the lung function and the number of fibers in the bronchoalveolar lavage fluid of Sprague-Dawley rats instilled with KC were estimated. Materials: Rats were administered 1 ㎎ KC by a single intratracheal instillation. At each time point(5 days, 5 weeks, 10 weeks), the lung function of the rats was analyzed by pressure transducer and the amount of asbestos in the bronchoalveolar lavage fluid of the rats was calculated by transmission electron microscope equipped with energy dispersive X-ray spectrometer. Results: The lung function of the rats at 5 days after instillation of KC was confirmed to be degraded. However, after 5 weeks the test groups showed a tendency to recover lung function. Still, after 10 weeks the lung function of the test groups had not recovered completely. The number of fibers in the bronchoalveolar lavage fluid of the rats instilled with KC rapidly decreased. At 5 weeks the number of fibers had reduced to approximately 1/2 of that found at 5 days. Over time, at 10 weeks it had rapidly decreased to 1/100 that found at 5 days. Conclusions: Korean chrysotile fibers rapidly decreased in the lungs of rats, but the lung function of rats instilled KC does had not completely recovered by 10 weeks.