• 한국정밀공학회지
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• 제15권12호
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• pp.28-36
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• 1998

This investigation is the result of a structural analysis by the finite element method and static loading test for the optimal structural design of an electric railway vehicle made of stainless 301L materials. We analyzed the stress and displacement of the existing electric car-body structure for predicting the position of concentrated stress, the flow of stress, rigidity to be occurred in the car-body structure when it is subjected to the vertical load. It was exposed that the side sills and window corners around the bolsters are the weak parts of the electric car-body structure because the bolsters of the electric car-body structure were subjected to the vertical load and dynamic load to be occurred during running. The flow of stress and the cause of stress concentration in the weak zone were studied in order to prevent the concentration of stress and buckling. The rearrangement of the structure and the selection of the beam elements were also carried out for optimum design of the structure.

• 한국식품영양과학회지
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• 제15권3호
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• pp.229-234
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• 1986

화분립(花粉粒)의 chloroform으로 인한 간(肝) 및 위장조직(胃臟組織)에 미치는 영향을 알기 위해 rat에 농도별로 chloroform을 투여하고 또 이들과 화분립(花粉粒)을 함께 투여(投與)한 결과, chloroform 농도가 증가할 수록 조직파괴 및 지방변성이 심했으며, 화분립(花粉粒)을 함께 투여(投與)함으로 조직파괴 정도가 약화됨을 알 수 있었고, 화분립(花粉粒)과 함께 투여(投與)하는 chloroform의 농도가 낮을수록 대조군(對照群)의 조직(組織)에 가까운 형태로 회복됨을 볼 수 있었다.

• 한국수자원학회논문집
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• 제33권6호
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• pp.815-825
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• 2000

Einstein(1942)의 부유사량 산정식 유도과정에 있어 몇 가지 문제점들을 개선하였다. 수류조건을 판별하여 완난류 조건에서 유속의 영점높이를 산정하는 방법을 제시하고 부유사량 산정식을 일반화할 수 있는 무차원수를 도입하였다. 또한, 기준점 농도 산정의 정확성을 개선하기 위하여 최근에 개발된 소류사량 산정식으로부터 관련치를 추정하였으며, 수치적으로 또는 도표를 이용하여 해를 구해야 하는 수심적분치의 근사식을 개발하였다. Einstein의 기존 부유사량 산정식과 개선된 부유사량 산정식의 정확도를 검토하여 Brownlie(1981)가 수집한 자료에 대한 산정결과를 제시하였다.

• Journal of Biosystems Engineering
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• 제15권3호
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• pp.177-185
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• 1990

The break of rotary blade is occured from a stress concentration of the inside of blade by the outside impulsive load. In order to examine its inside stress and stress concentration of rotary blade, a epoxy plate which is suitable to applicate by photoelastic system is used to experiment. These results are summarized as follow. 1. Refer to the existence of bolt hole and a size of its of rotary blade, a stress concentration which cause the break of rotary blade is not exposed. 2. It is expected to be break to section of hold of rotary blade and the break of this is due to that there are concentrated by shearing force, bending moment and bending stress. 3. When the crack which caused from processing are set up to any location, the stress concentration taken to the creak point. 4. Without regard to the location of the reaction points of rotary blade, the bending stress which is greated than the bending moment is occured within about 6 em toward the center line of bolt hole and it was possible to break that section.

• 대한기계학회논문집
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• 제8권2호
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• pp.127-132
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• 1984

본 연구에서는 상술한 점들을 고려하고 우선 다음과 같은 사항을 고찰하려고 노력하였다. 즉 슬롯 및 노치주위에는 어떤 응력들이 분포되며 응력분포거동은 어떤 인자에 의하여 좌우되는가, 어떤 응력이 응력집중을 지배하며 응력집중현상은 어떤 인 자에 의하여 좌우되는가를 주로 고찰하였다. 참고로 실험에서 노치 및 슬롯선단의 응력측정에는 실제로 기계나 구조물에 직접 사용할 수 있는 스트레인 게이지를 사용하 였고 측정치의 정도를 높이기 위하여 스트레인 게이지율 교정방법을 이용하였다. 참 고로 노치 및 슬롯주위에 발생하는 응력집중과 파괴거동과의 관계에 대해서는 다음에 보고하겠다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 추계학술대회 논문집
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• pp.160-163
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• 2001

In order to develop a nodule conveying system through a flexible pipe out of the deep-seabed manganese nodule miner, an experimental study of the solid-water slurry flow in vertical pipe is performed as the first stage of total experiments. Hydraulic characteristics of the pipe slurry flow such as slip velocity, transport concentration and pressure gradient are investigated for the size of particle, load ratio, and flow rate of water. The higher the load ratio is, the larger the transport concentration and pressure gradient become. The bigger the size of particles is, the larger the pressure gradient becomes. The effectiveness of the flow rate to hydraulic performance is also investigated. This results are to be used for designing crusher and pump, and operating the conveying device.

• 환경위생공학
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• 제13권1호
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• pp.135-146
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• 1998

In this study, we investigated to measured concentration, seasonal characteristics and load quantity of volatile organic compounds(VOCs) for 11 sites in the main stream and 8 sites in the branch stream of Kumho river, during from October 1995 to April 1997. As a results, the small amount of volatile compounds, such as dichloromethane, chloroform, toluene, benzene, trichloroethene, tetrachloroethene, p-xylene and 1,3,5-trimethyl-benzene were detected from the main stream of Kumho river. Also detected to dichloromethene, chloroform, toluene, benzene, trichloroethene, tetrachloroethene, ethylbenzene, p-xylene, 1,3,5-trimethylbebzene and 1,2,4-trimethylbenzene in the branch stream, and dichloromerhane, chloroform and toluene were detected to all site of sampling. And seasonal variation of volatile organic compounds showed higher concentration in the July 1996 as a winter season than January 1997 as a summer season in most places. Also the load quantity of volatile organic compound at Gangchang site in the last downstream of Kumho river, was in order of chloroform > dichloromethane > toluene > trichloroethene.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.222-227
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• 2004

Under cyclic loading, the fatigue failures of welded joints occur at weld toes which induce stress concentration by weld shape. So we need to obtain the peak stress and the S-N curve to assess the fatigue strength of welded joints. However the measurement of peak stress is of high uncertainty and low reproducibility, so we use nominal stress instead in fatigue tests of welded joints. In this study, fatigue tests to obtain S-N curves and FE analyses to obtain stress concentration factors were conducted for the two types of cruciform fillet welded joints, that is, load-carrying and non load-carrying types. Then we changed the obtained S-N curves to that based on peak stress using the hot-spot stress concept. From the analyses of the S-N curves obtained, we have concluded that there is a need to develop a new method to evaluate the fatigue life.

• 한국자동차공학회논문집
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• 제6권6호
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• pp.142-154
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• 1998

The effects of recirculated exhaust gas on the characteristic of soot emissions have been investigated by using an eight-cylinder, four-stroke, direct injection and water-cooled diesel engine operating at several loads and speeds. The experiments in this study are carried out at the fixed fuel injection timing of $38^{\circ}$ BTDC regardless of experimental conditions. The intake oxygen concentration and the mean equivalence ratio calculated by the intake air flow and fuel consumption rate are used to analyze and discuss the influences of EGR rate on soot emissions. Results of this study indicate that soot emissions increase owing to the drop of intake oxygen concentration and the rise of equivalence ratio as the EGR rate increases at a given engine load and speed, especially the high load.

• 대한치과보철학회지
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• 제25권1호
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• pp.55-69
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• 1987

The purpose of this study was to evaluate the stress distributions of the fixed partial denture with five unit intermediate abutment. This fixed partial denture was attached to a three dimensional photoelastic epoxy resin model. Three dimensional photoelastic models were used, with the stress areas recorded photographically. A vertical load was applied to the second molar, which is the most posterior abutment of the fixed partial denture. Similarly, a vertical load was applied to the first molar because this tooth receives the heaviest masticatory load. These loads were added to two types of fixed partial denture. the rigid connector, and the nonrigid connector which was connected on the distal side of the intermediate abutment by a key and keyway device. After the stress patterns in surrounding tissues were observed, the following conclusions were as follows: 1. When the vertical load was applied to the first and second molars on the occlusal surfaces, the surrounding tissues of the roots of the canine, the second premolar, and the second molar were all compressive stresses. 2. When the vertical load was applied on the occlusal surface of the second molar, the tissue surrounding the roots of the canine, the second premolar, and the second molar all showed more stresses with the nonrigid connector than with the rigid connector. 3. When the vertical load was applied to the occlusal surface of the first molar, the stress concentration on the canine and the second molar was similar, whether the rigid or nonrigic connectors were used. However, on the second premolar, the stress concentration shown by the nonrigid connector was noticeably more than that shown by the rigid connector. 4. Whether the rigid or nonrigid connectors were used, when the load was placed on the first molar, the stress concentration on the canine and the second premolar was greater than that observed for the second molar. When the load was placed on the second molar, the load affected the second molar more than the canine and the second premolar.