액체로켓엔진 시스템 Lay-out 설계 개념 연구

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.

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.

액체로켓엔진 시스템 정현파 진동 구조해석

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.

3-MCPD의 생식˙발생독성에 관한 연구

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.

A Study on GHS Classification of Potassium nitrate by acute oral Toxicity

Yong Hyun Chung(정용현) 환경독성보건학회 2017 한국독성학회 심포지움 및 학술발표회 Vol.2017 No.5

A study on health hazard classification of Potassium nitrate by acute dermal toxicity test

Yong Hyun Chung(정용현) 환경독성보건학회 2018 한국독성학회 심포지움 및 학술발표회 Vol.2018 No.6

LCA 기법을 이용한 사각형어초 개선에 관한 연구

정용현(Yong-Hyun CHUNG) 한국수산해양교육학회 2023 水産海洋敎育硏究 Vol.35 No.6

This study performed a Life-cycle assessment by process and material to identify and improve the environmental impact on the producing process of cube type reef. The producing process consists of a rebar assembly process, a steel formwork manufacturing process, a concrete pour process, and an artificial reef manufacturing process. And the MiLCA ver 2.3 program was used as the life-cycle assessment program. The environmental impact categories were global warming, resource consumption, acidification, photochemical oxidant, ozone depleting, eutrophication, ecotoxicity-quatic, and ecotoxicity-territorial impact categories, and a total of eight environmental impact categories were evaluated. As a result of inventory analysis, a total of 201 inventory items were derived, and as a result of impact evaluation, it was found that concrete pour process and rebar assembly process had a large environmental impact in 7 environmental impact categories excluding resource consumption. As a result of the life-cycle assessment by material, it was found that the potential environmental impact due to steel bar and concrete was the greatest in most environmental impact categories. The results of this study suggest that it is necessary to improve the concrete pour process and rebar assembly process in the artificial reef producing process, and to improve the materials used in the steel formwork manufacturing process.

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.

그웬 한센 피곳(Gwyn Hanssen Pigott)의 작품연구

정용현(Chung Yong hyun) 한국조형디자인학회 2015 조형디자인연구 Vol.18 No.1

그동안의 도예작업은 기(器)의 제작이나 질료, 제작기법 등을 중심으로 한 형상과 기술적 측면을 강조하는 일반적인 성향을 보여 왔다. 본 연구는 용기를 대하는 사고와 공간을 이용하는 방식 등의 흥미로운 표현법으로 지속적으로 다양화 되는 현대도예의 흐름을 이끌어간 한 도예가에 대한 것이다. 이 연구는 확장된 현대도예 안에서 그웬 한센 피곳의 작업배경과 작품들을 살펴봄으로써, 그의 삶을 조명하고 작품이 지닌 가치에 대해 그 의의를 발견하고자 한다. 한센 피곳은 기(器)라는 기존 도자공예의 전통적 범위에서, 그것을 이용한 또 다른 시각을 보여주는 예술작품을 하였다. 즉, 일상생활에서 쓰이는 도자기를 이용하여 '정물그룹(Still Life Group)' 설치를 통한 예술적 작품을 만들어 현대도예의 확장된 영역을 보여주었다. 한센 피곳의 작품은 대부분 용기의 형태로 이루어져 지극히 공예적 모습을 띄고 있으나 현대적인 감각으로 마무리되어 완벽함이 보인다. 다양한 크기와 형태의 용기를 이용하여 크고 작은 그룹을 지어 설치의 형식으로 여러 작품들을 선보였다. 컵이나 병, 주전자 같은 일상적인 도자사물에 대한 인식과 그것들을 모아 만든 전체적인 모습, 그리고 공간에 대한 이해는 우리에게 신선하게 다가오며 응시하며 명상할 수 있는 시간을 준다. 한센 피곳은 호주, 미국, 유럽 등 세계 각지에서 활발히 예술 활동을 하였지만 국내에 연구된 바가 미비한 수준이다. 이에 본 연구를 통해 한센 피곳의 작품을 연구하고 이해하는데 도움이 될 수 있기를 기대한다. 따라서 본 논문은 먼저 한센 피곳의 생애와 작품배경을 통해 작가로서의 발전과정과 조형개념을 생성하게 된 배경을 살펴보고. 두 번째로는 한센 피곳의 작품세계에 대한 연구로 정물화가 조르지오 모란디(Giorgio Morandi)의 작품에서 영감을 받은 정물그룹(Still Life Group)과 도예가 한스 코퍼(Hans Cooper)와 도가사상과 연결되는 네거티브 스페이스(Negative Space)에 대한 생각들을 살펴봄으로써 작품의 미적가치와 개념적 의미에 대해 고찰해 보고자 하였다. This paper is about an ceramic artist who leads the continuously diversified trend of contemporary ceramic art beyond propensity for vessel oriented work, material, techniques in ceramic art and through interesting expression like different thoughts on pottery and ways using space. This study aims to look into Gwyn Hanssen Pigott's life and finds out significance of her work by researching her background and work in extended contemporary ceramic art. Hanssen Pigott did the art that showed us another perspective of pottery within traditional ceramic craft boundary. That is she showed the extended territory of contemporary ceramic art through making 'still life group' installation by using daily use pottery. Hanssen Pigott's works are composed of mostly vessel forms, so have characteristics of craft; they are modernized and finished perfectly. She did various installation works by grouping with a various sizes and forms of pottery. The installation view of her work by cups, bottles, teapots and etc. and understanding about space gives us meditative time. Hanssen Pigott did lots of art activities throughout the world like Australia, USA and Europe, but there is lack of study of her artwork. It is expected that a help to study and appreciate her artwork through the study. Hence, in this paper, we get to know about the artistic development and background of formative concept through looking into her life career at first. Secondly, about study on her art world, the ideas of still life group inspired by Giorgio Morandi, Italian painter, and negative space inspired by Hans Cooper, ceramic artist, and Taoism are examined to consider aesthetical value and conceptual meaning.

랫드에 주입된 세피오라이트에 의한 호흡기독성 연구

정용현(Yong Hyun Chung),한정희(Jeong Hee Han),성재혁(Jae Hyuck Sung),유일재(Il Je Yu) 한국독성학회 2006 Toxicological Research Vol.22 No.3

Two kinds of sepiolite, a 500℃ heat-treated sepiolite, and a 700℃ heat-treated sepiolite were analyzed for their physicochemical properties. After these sepiolites were instilled into rat lungs, the effects of the substances on lung pathological changes were evaluated. The lungs instilled with sepiolite increased their weight compared with the unexposed control. The pathological examination further showed increased legions of granuloma with early fibrosis. The heat treated sepiolites, however, did not show any toxicological differences from the untreated sepiolites. Thus chronic experiments are needed to evaluate the durability of mineral fibers, which is an essential experiment for evaluating biopersistence of fibers in lungs.