• 대한교통학회지
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• 제14권3호
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• pp.155-172
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• 1996

This study is to analyze speed variation at merging section of successive entrance ramp and to suggest design criterion of ramp spacing at successive entrance ramp in urban area. The major findings are as follows ; (1) The relationship between the speed at merging section of successive entrance ramp and the distance from the merging point represents concave curve. (2) The 85 percentile speed(S) at outside lane (lane 1) is modeled S = 49.5 + 355.7(D/Q) - 0.94(D2/Q) + 6.78(D/AL2) where, D = Distance from merging point(m), Q = Lane 1 volume(vph) AL2 = Acceleration length at second entrance ramp(m) (3) The more traffic volume and the shorter acceleration length of the second entrance ramp, longer ramp terminal spacing is needed.

• 대한토목학회논문집
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• 제30권4D호
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• pp.369-376
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• 2010

현재, 단지 내 진출입 불허구간의 설치 및 운영에 대한 명확한 설치기준이 없어 교통소통과 안전에 많은 문제가 발생하고 있는 실정이나, 단지 내 진출입 불허구간에 관한 연구는 미흡하여 합리적인 설계가 이루어지지 못하는 실정이다. 이에 본 연구에서는 단지 내 진출입 불허구간을 진입부와 진출부로 분류하여 진 출입부 적정길이를 산정하였다. 진입부 적정길이 산정은 횡단보도 위치 및 정지선 이격거리와 2차로 진입차량 대기행렬 길이, 안전을 고려한 여유거리 등을 고려하여 산정하였으며, 진출부 적정길이 산정은 횡단보도 위치 및 차량길이와 가로교차로 진출차량의 행태를 고려하여, 조사지점과 거리별로 진출부 차간간격을 비교 분석하여 산정하였다. 이와 같이 단지 내 진출입 불허구간을 대상으로 차량행태 조사와 교통소통 및 안전을 고려한 진출입 불허구간의 적정길이를 제시함으로써, 향후 단지 내 진출입 불허구간의 적합한 설치기준 및 운영에 이바지할 것으로 판단된다.

• 한국항해항만학회지
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• 제37권6호
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• pp.597-601
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• 2013

최근 해양시설물용 파력발전시스템은 본래 기능과 연계한 하이브리드 형태로 많은 연구개발이 이루어지고 있다. 이 중 방파제에 설계된 진동 수주형 파력발전시스템의 경우, 기존의 방파제의 기능에 더불어 터빈을 통해 파랑에너지를 전기에너지로 변환하는 발전기능을 갖는다. 이러한 형태의 발전 시스템은 해수를 손실 없이 최대한 많이 유입되도록 하는 것이 중요하다. 본 논문에서는 유입구 형상에 따른 파력발전시스템의 출력 특성에 대해 기술하였다. 또한 일반적인 해양 구조물인 방파제에 부착된 진동수주형 웰즈터빈 모델을 시뮬레이션 하여 유입구 곡면 각도에 따라 변화하는 유입량과 해수속도 그리고 그에 따른 웰즈터빈의 출력을 측정하였다. 마지막으로 시뮬레이션 결과를 바탕으로 하여 에너지 변환 효율을 높이기 위한 유입구 형상을 제안하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.130-135
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• 1997

A kinematically admissible velocity field is developed for the analysis of twisting of extruded products. The twisting of extruded product is caused by the linearly increased rotational velocity from the center on the cross-section of the workpiece at the die exit. In the analysis, the rotational velocity in angular direction is assumed by the multiplication of radial distance and angular velocity. The angular velocity is zero at the die entrance and is increased linearly by longitudinal distance from die entrance. The increase rate of angular velocity is determined by the minimization of plastic work. The results of the analysis show that the angular velocity of the extruded product changes with the aspect ratio of product and increases with the decreases in die length and in eccentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-section at the die exit.

• 한국도로학회논문집
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• 제15권1호
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• pp.143-154
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• 2013

PURPOSES: Design of approach roads of rest areas in highway has many drawbacks such as geometric design elements. There has been traffic accidents occured in these approach roads of rest areas. Thus, design criteria is required in order to protect accidents from being occurred. In case of Korea, geometric structure design criteria of entry facilities, such as toll-gate, interchange, junction etc was established. However there are no presence in a detailed standards for geometric structure of the rest area which affiliated road facilities. METHODS: In this study, analytic on accidents was carried out in regards to the entry of geometric structure of resting areas by utilizing a sight survey and an investigation research of traffic accidents. The survey was targeting 135 general service areas. Collisions with physical channelization and safety facilities occurred due to speeding, rapid entry, and etc at the entrance nose section. At the entrance connector roads, accidents caused by speeding, negligence, over-operation of handle of drivers were main reason of accidents. Discriminant analysis were conducted about geometric elements to distinguish influencing factors for traffic accidents. the lengths and access angles of the entrance connector roads were regarded as to have the high relation with traffic accidents. RESULTS: After classifying the design section of resting areas' entry as well as derive design elements on each section, a speed measurement by targeting entry of rest areas and car behavior surveys were performed, then each element's minimum standard was derived through the analyses. According to the speeds at the starting/end point of entrance connector road, the range of the junction setting angle of the entrance connector road is defined as $12^{\circ}{\sim}17^{\circ}$ and the connector length model was suggested. CONCLUSIONS: Suggest improvement plans for existing rest areas that can be applied realistically. This should be corresponded to the standards of entry and exit of developed rest areas.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 추계학술대회논문집
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• pp.7-13
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• 1996

The kinematically admissible velocity field is developed for the analysis of extruded products. The curving of product in extrusion is caused by the linearly distributed longitudinal velocity on the cross-section of the workpiece at the die exit. In the analysis, the longitudinal velocity in extrusion direction is divided into the uniform velocity and the deviated velocity. In order to satisfy the requrement of the kinematically admissible velocity field, the average value of the deviated velocity should be zero. At the same time, it should linearly change with the distance form the center of gravity of the cross-section of the workpiece. The results of the analysis show that the curvature of product increses with increses in eccentricity of gravity center of the cross-section of workpiece at die entrance form that of the cross-section at the die exit. In the analysis, the longitudinal velocity in extrusion direction is divided into the uniform velocity and the deviated velocity. In order to satisfy the requrement of the kinematically admissible velocity field, the average value of the deviated velocity should be zero. At the same time, it should linearly change with the distance from the center of gravity of the cross-section of the workpiece. The results of the analysis show that the curvature of product increses with increses in ecentricity of gravity center of the cross-section of workpiece at die entrance from that of the cross-section at the die exit.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.238-239
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• 2006

Nozzle geometry influences gas dynamics making sprayed particle behavior one of the most important parameters in cold spray process. Gas flows at the entrance convergent section of the nozzle takes place at relatively high temperature and are subsonic. Thus, this region is a very suitable environment for heating spray particle. In this study, numerical simulation and experiments were conducted to investigate the effect of nozzle contour, entrance geometry of nozzle and powder injection position at nozzle on the cold spray process. The process changes were observed through numerical simulation studies and the results were used to find a correlation with coating properties.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.31-34
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• 2004

A new extrusion process of the circular section product with helical fins could be developed by using rotating extrusion dies. The twisting of extruded product is caused by the twisted conical die surface connecting the die entrance section and the die exit section linearly. But, until now, because the process has used fixed extrusion dies, it needs high pressure in order to twist billet and form fin shape on the surface of billet. So, during extruding billet, in order not to twist billet, the extrusion dies is needed to rotate itself instead of twisting billet. And in order to rotate dies, the shape of inside contour of extrusion dies must have conical type with twisted Inclined die surface connecting the die entrance section and the die exit section linearly. The results of experiments show that, in spite of using twisted extrusion dies, twisting of the billet should not happen because of rotating dies in the opposite direction of twisting direction of billet during extruding billet, and, from the results, it shows that it can decrease the power of extrusion pressure and could prevent crack of teeth for fin forming.

• 전기학회논문지
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• 제64권2호
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• pp.247-253
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• 2015

Dielectric breakdown accidents have been mainly occurred in the vicinity of service entrance section in underground power transmission systems. One cause among them is due to the excessive component value of sheath located around service entrance of cable. In this paper, as one of the alternative to prevent these accidents, the change of cross bond grounding system and the location change of IJ(Insulation Joint) are suggested. Also, to evaluate effectiveness of this changing system, circulating current and induced voltage of sheath were analyzed in steady and transient state. By comparison of the analytical results for the several possible changing systems, a grounding system and location of IJ which has the smallest sheath component values is proposed. In this paper, analysis to evaluate the proposed system is carried out by EMTP/ATPDraw. It can be used as a valuable operational material to prevent accident of the service entrance section in underground power transmission system.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.977-980
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• 2011

본 논문에서는 항공우주연구원에서 개발중인 1단 저압 축류압축기 성능시험리그의 개발에 대한 내용을 소개하고자 한다. 성능시험리그는 유동 입구부, 동익단, 정익단, 축, 리그 하우징, 베어링 하우징 및 유동 출구부로 구성되어 있다. 로터와 회전축을 단순화하여 회전동역학 해석 결과를 바탕으로 회전축을 설계하고 입 출구 유로의 유동해석을 통해서 시험리그 형상설계를 최적화하였다.