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尹鍾鎬,金得浩 慶一大學校 1998 論文集 Vol.15 No.1
The exhaust pipes are analysed by the FEM, where the geometry, the mass, and the stiffness of them are modeled. The validity of the developed model is verified by comparing with the experimental results. It is also proved that this analytical method is quite useful in the design stage of the exhaust system. When a bended pipe is modelled with straight beam elements, its stiffness, particularly in bending behavior, is overestimated than its true value. In this paper, we propose a simple and practical beam-modelling technique to estimate its stiffness properly. When this technique, based on the strain energy concept, is employed to modify the beam sectional properties of the bend, the quite satisfactory results can be obtained. To verify the validity of this method, we apply the present technique to the free vibration analysis of a two point-bended circular pipe with fixed-free boundary condition, and the real car exhaust system model with free-free boundary condition. Estimated modal parameters are in accord with the experimental results. From these results, we can also predict the locations of the hangers at the nodes of mode shapes.
낙동강 중류 유역의 단열계 특성 및 지하수계와의 관련성
김득호 ( Deuk Ho Kim ),이종현 ( Jong Hyun Lee ),박규태 ( Kyu Tae Park ),김성창 ( Seong Chang Kim ),최유미 ( Yu Mi Choi ),서유리 ( Yu Ri Seo ),노경명 ( Gyung Myung Noh ),함세영 ( Se Yeong Hamm ) 대한지질공학회 2008 지질공학 Vol.18 No.4
낙동강 중류 지역(함안군, 창령군, 의령군)의 백악기 퇴적암의 단열계 특성(단열의 방향성과 단열계 밀도도)을 파악하고, 단열과 단층, 수계 그리고 연구지역내 지하수공의 일일 사용량과의 관련성을 분석하였다. 단열계는 JI(N90°-110°E), J2(N0°-35°E), J3(N0°-35°W)로 분류되며, 주로 남북방향과 동서방향 단열군의 방향성이 우세하다. 연구지역의 동편과 서편의 함안층 분포지역에서는 남북방향의 단열계가 우세한 반면에, 연구지역의 중간부분인 칠곡층 분포지역에서는 동서방향의 단열계가 우세하다. 이는 연구지역의 동편과 서편에 위치하는 북북동-남남서 방향의 단층계와 관련되는 것으로 보인다. 또한 낙동강 주변에서도 단열 밀도가 높게 나타나며, 이는 동서방향의 단열계가 낙동강과 연관됨을 암시한다. 한편, 연구지역내 지하수공의 일일 사용량과 단열 밀도 간에는 약한 양의 상관성을 보이며, 지하수 비양수량과 단열 밀도간에는 음의 상관성을 보인다. 이는 단열 밀도가 지하수 산출량을 결정하는 주요 요인이 될 수 없음을 지시한다. The characteristics of joint system (joint orientation and density) were studied for Cretaceous sedimentary rocks in the Nakdong River mid-basin (Haman-Gun, Changnyeong-Gun, and Uiryeong-Gun areas), and were related with faults, river system, and groundwater usage in the study area. The joint system was classified into JI (N90°-110°E), J2 (N0°-35°E), and J3 (N0°-35°W), and was dominant along N-S and E-W directions. The N-S trending joint system is dominant in Haman Formation in the eastern and western parts of the study area, while the E-W trending joint system is prevalent in Chilgok Formation in the central part. The joint system may be associated with the faults located in the eastern and western parts in the study area which are elongated to NNE-SSW direction. Additionally, the joint density is higher along the Nakdong River, indicating close relationship between E-W trending joints and the river. Daily groundwater discharge versus joint density shows weak positive relationship, and specific capacity versus joint density appears negatively related. This indicates that groundwater occurrence does not greatly rely on joint density.