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구윤서,신동윤,이정주 용인대학교 자연과학연구소 1998 自然科學硏究所論文誌 Vol.3 No.2
This study was predicted of ventilation effects from natural ventilation using windows at high temperature passage. Predict method was numerical model simulation by using RNG (Renormalization Group) k-ε turbulence model, because well describe in heat turbulent phenomenon. Result of this study, if exclude heat flux and open a all windows, predicted not over 40℃ in passage temperature at outdoor air temperature 34℃ in summer season.
被蔭이 Angelica takesimana의 物質生産에 미치는 效果에 關한 硏究
李一球,金源,徐貞姬,李浩俊 建國大學校附設 應用科學硏究所 1979 理學論集 Vol.5 No.-
A cultural experiment was performed on Angelica takesimana Plant in order to investigate the dry matter production under varying relative light intensity. The light level in this experiment was 7%, 30%, 50%, 70%, and 100%(control) daylight. The varying light intensities were controlled by reed and nylon screens supported on wooden frames (2m×1.2m×0.7m). Under these conditions the growth or dry matter production of the samples was observed. The results are summarized as follows: 1. The growth patterns of Angelica takesimana in total dry matter production per individual in the last sampling were generally divided into three groups: 70%, 50%-100% and 7%-30%. And the growth of Angelica takesimana in total plant dry weight was high value in the 70% daylight and in deeper shade(7% and 30% daylight) the dry matter production was evidently depressed by shading in later stage. 2. In growth pattern, the C/F ratio showed high value in the 50% and 100% at the first sampling, but at the last sampling was the highest value in the 7% daylight. 3. The T/R ratio showed low value in the 50% and 100% at the first sampling, and it was decreased from 3.2464 to 1.2953 in accordance with the passing of time in the 7%, 30%, and 100%, but it was increased in the 50% and 70% from 2.4229 to 4.1986 in course of the day. 4. The number of the branches was highest in the 70% group, but was not increased in the 7% group.
안양천 등 관내하천의 수질오염분석 및 생태학적 분석에 관한 연구(II)
배준현,서정범,구본영 안양대학교 자연과학연구소 1997 自然科學硏究 Vol.4 No.-
안양천을 비롯한 10개 지천에 대한 환경오염 분석을 하였다. 전편(Ⅰ)에 이어 안양천의 관내지류인 산본천, 당정천, 오전천, 왕곡천, 통미천을 중심으로 하여 수질오염분석과 중금속오염도 조사 및 생태학적 분석에 대하여 연구하였다. 아울러 안양천 및 그 지류의 환경진단과 함께 하천을 살릴수 있는 몇가지 제안을 하였다. 안양천 및 지류의 수질오염분석결과 측정기간에 BOD 값이 평균 25.5 mg/l으로, 최저 17.0mg/l에서 최고 36.4mg/l으로 환경기준치를 초과하고 있다. COD는 평균 18.9mg/l으로 최저 12.7mg/l에서 최고 24.2mg/l로서 환경기준치인 5급수 수질을 초과하고 있으나 다른 수질의 지표에 비해 비교적 양호한 값을 나타내고 있다. SS는 평균 23.8mg/l으로 3급수 이내의 수질을 유지하고 있다. 총질소(T-N)는 평균치가 16.7mg/l으로 상류는 기준치 이하를 나타내고 있으나 중·하류는 5급수 이상의 높은 수치를 보이고 있어 제거대책이 강구되어야 할 것이다. 하천퇴적물에 대한 중금속 오염도 분석결과 5개항목 모두 기준치를 초과하여 높게 나타났으며 특히 아연(Zn)의 농도는 매우 심각한 것으오 분석되었다. 분석결과는 Zn>Cu>Pb>As>Cd순으로 나타났다. 생태학적 분석에 있어서는 안양천의 상류에서 하류에 이르기까지 어류는 서식하지 못하고 있으며 하류일부지역에서 오염에 강한 극소수 어류가 발견되었다. 식물도 하류로 갈수록 오염에 비교적 강한 식물이 군락을 이루고 있었다. Water pollution analysis about Anyangchun river and rivers within the province, investigation of a contamination level of heavy metal and ecological analysis were studies. The result of water pollution analysis Anyangchun river and its tributaries during the period of measure says BOD was average 25.5mg/l, ranging from minimum 17.0mg/l to maximum 36.4mg/l which exceeds and environmental standard level COD was average 18.9mg/l, ranging from minimum 12.7mg/l to maximum 24.2mg/lwhich exceeds fifth class of water quality, and environmental datum level, but represents relatively better value than the other base point of water quality. SS was average 23.8mg/l, which maintains water quality of below the third class. Total Nitrogen was average 16.7mg/l ; the upper water was seen below a base point, but the middle and lower showed exceeds fifth class of water quality. Therefore, a proper measure to remove nitrogen will have to be deviced. According to the analysis result of heavy metal contamination level about the river deposit, all of 5 items exceeded the environment base point. Specially, concentration of Zinc was considered very serious. The result of analysis was proven in the order to Zn>Cu>Pb>As>Cd. In ecological analysis, fish couldn't living from the upper water to the lower one in Anyang river with in province and a small minority of fish were discovered in part of the lower water. Hereby we suggested the alternative to decline water pollution in Anyang watercourse.
1차원 모델을 이용한 한국형 고속전철의 충돌 안전도 평가
구정서(Koo Jeong Seo),조현직(Cho Hyun Jik),김동성(Kim Dong Sung),윤영한(Youn Young Han) 한국철도학회 2001 한국철도학회 학술발표대회논문집 Vol.- No.-
The best method to evaluate crashworthiness of a trainset as a whole is to analyse one dimensional dynamic model composed of nonlinear dampers, springs and bars, and masses. In this study, crashworthiness of KHST was evaluated by analysing a nonlinear spring/bar-damper-mass model. The numerical results show that the KHST can easily absorb kinetic energy at lower impact force and acceleration in a heavy collision, when compared with KTX. Also, the KHST can be protected from any damage in its carbody and components except the prepared energy absorbing tube in a light collision, like a traint-to-train accident at speed under 8 kph. However, the KTX can be much damaged in the a light collision because there is no energy absorbing tube.
구정모(Jeong-Mo Koo),이광은(Gwang-Eun Lee),서정미(Jeong-Mi Seo),원태훈(Tae-Hoon Won) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.9
회전익 항공기는 블레이드 회전을 이용하여 양력을 발생시키기 때문에 진동의 영향에서 자유롭지 못하다. 이러한 진동을 줄이기 위하여, 승객실과 조종석 등에 진동흡수장치가 적용된다. 그 중 진동흡수용 판스프링은 조종석 하부에 장착되며, 조종사가 느끼는 진동을 줄여주는 역할을 한다. 본 연구에서는 회전익 항공기에서 발생한 판스프링 결함에 대한 원인을 분석하고 개선안을 제시하였다. 결함 원인 분석을 위하여, 구조해석과 파단면 분석을 진행하였으며, 결함원인은 피로수명 특성 저하로 나타났다. 기존 재질을 대체할 개선 재질 2가지의 적용사례 및 타당성을 분석하여 최종 개선안을 선정하였다. 최종 개선안은 GFRP(Glass Fiber Reinforced Plastics, 유리섬유 복합재)이며, 개선안 검증을 위한 시험을 수행하였다. 판스프링 구조물에 작용하는 공진을 모사하는 가진 시험기를 이용하여 피로시험을 진행하였다. 시험방법은 S-N 피로시험으로 진행되며, 평균 피로 수명 곡선(Mean Fatigue Curve)을 생성하여 수명을 비교하였다. 판스프링 내부 고체윤활제 재질 개선을 통하여 피로강도와 수명이 기존대비 1.5배 이상 증가함을 입증하였다. A rotorcraft is not free from the effects of vibration because it generates lift using the blade rotation which is a source of vibration. To reduce the vibrations in a rotorcraft, a vibration-absorbing device is used in the passenger compartment and cockpit. Among the various vibration-absorbing devices, the vibration-absorbing plate spring is widely used and installed in the lower part of the cockpit to reduce the vibration felt by the pilot. This study analyzed the causes of plate spring defects in rotorcraft and presented suggestions for improvement. To analyze the causes of the defects, structural and fracture surface analyses were performed, and the cause of the defect was found to be the deterioration of fatigue life characteristics of the spring material. The final improvement plan was obtained by analyzing various application cases and the feasibility of using two improved materials to replace the existing materials. The final improvement proposal is the use of GFRP (Glass Fiber Reinforced Plastics), and a test was performed to verify this proposal. A fatigue test was conducted using an excitation tester that simulates the resonance acting on the plate spring structure. This test method is an S-N fatigue test, and the lifespan was estimated and compared with that of the other materials by creating a Mean Fatigue Curve. It has been proven from this study that the fatigue strength and lifespan are increased by more than 1.5 times compared to the existing ones by the improvement of the solid lubricant material inside the plate spring.