• Geomechanics and Engineering
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• 제19권3호
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• pp.269-282
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• 2019

Due to top-coal and immediate roof as cushion layer connecting with support and overlying strata, it can make significant influence on strata behaviors in fully mechanical top-coal caving working face (TCCWF). Taking Qingdong 828 working face as engineering background, $FLAC^{3D}$ and $UDEC^{2D}$ were adopted to explore the influence of top-coal thickness (TCT), immediate roof thickness (IRT), top-coal elastic modulus (TCEM) and immediate roof elastic modulus (IREM) on the vertical stress and vertical subsidence of roof, caving distance, and support resistance. The results show that the maximum roof subsidence increases with the increase of TCT and IRT as well as the decrease of TCEM and IREM, which is totally opposite to vertical stress in roof-control distance. Moreover, although the increase of TCEM and IREM leading to the increase of peak value of abutment pressure, the position and distribution range have no significant change. Under the condition of initial weighting occurrence, support resistance has negative and positive relationship with physical parameters (e.g., TCT and IRT) and mechanical properties (e.g., TCEM and IREM), respectively.

• 한국해양공학회지
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• 제31권5호
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• pp.357-363
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• 2017

The sloshing pressure acting on a membrane-type LNG CCS is a typical irregular impact load, and the structural response of a tank system induced by sloshing also shows very complex behavior, including fluid structure interaction. Therefore, it is not easy to accurately estimate the sloshing impact pressures and resulting structural response. Moreover, a huge time consuming process to deal with the enormous pressure data obtained during a model tank test and the following structural analysis would be inevitable. To reduce the computation time for structural analysis, in this study, a rational structural modeling strategy was considered, and a simplified scheme to analyze the dynamic structural responses of an LNG CCS was introduced, which was based on the concept of the linear combination of the triangular response functions obtained by a transient response analysis of structures under unit triangular impact pressure. A structural analysis of a real Mark III membrane type insulation system under the sloshing impact pressure time histories obtained by model tests was performed using the various proposed structural models and simplified analysis scheme. The results were investigated in detail, including the elastic support effects of the hull structure.

• 한국방재학회 논문집
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• 제8권3호
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• pp.11-21
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• 2008

여러 가지 하중을 받는 임의의 탄성 경계 지지된 판과 쉘의 기하학적 선형 및 비선형해석을 수행하였다. 가정변형률 9절점 쉘 요소를 이용하였으며, 임의의 탄성 경계 지지를 표현하기 위해 6개의 자유도를 갖는 스프링 요소가 사용되었다. 탄성 경계지지 구조물 해석의 응용을 위하여, 여러 형태의 단부 지지를 받는 판과 쉘이 분석되었으며, 이들 단부 지지에 대한 휨 거동을 정확히 얻을 수 있었다. 6개의 스프링으로 표현된 탄성 경계 지지 조건에 대하여 적절한 결과를 얻을 수 있었다. 해석 결과로부터 본 연구의 해석 방법이 임의의 탄성 경계 조건을 갖는 판과 쉘의 거동을 해석하는데 폭넓게 사용될 수 있음을 알 수 있었다.

• 한국농공학회지
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• 제24권3호
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• pp.73-83
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• 1982

study aims to derive a rational method for the analysis of the farm silo supported on an elastic foundation in which it is assumed that the reaction pressure of the soil at a point is proportional to the deflection at that point. In order to investigate the effects of an elastic foundation on the behaviour of the structures on it, the analysis of the farm silo resting on an elastic foundation was compared with the solution that the ground support may be assumed uniform (which was obtained from part I of this paper). To calculate the deformation of an elastic foundation, Boussinesq's solution which allows an interaction of the various parts of ground was adopted. In this case, the foundation was treated as a superparametric element additionally. In the evaluation of an element stiffness matrix, Gauss quadrature' was used. In above numerical integration, 3-point rule for the farm silo wall and the footing was introduced and 2-point rule for the evaluation of a reaction between the footing and the elastic foundation was adopted. The stresses of a farm silo on an elastic foundation were smaller than those which the distribution of contact pressure between the footing and the soil is assumed uniformly. Since the differences of stresses were remarkable in PS structures than RC structures, it is desirable that designers take into account the effect of an elastic foundation for the case of PS structures. It can be noted that while the effect of an elastic foundation was more conspicuously observed in near of the ground, the value of stresses at far from the soil was little affected by an supported soil.

• 대한토목학회논문집
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• 제28권3A호
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• pp.367-373
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• 2008

국내/외에서 설계되는 강곡선거더교 복부판의 전단강도는 복부판의 4변을 단순지지라는 가정 하에서 산정되는 탄성전단좌굴강도로 제안하고 있다(AASHTO Guide Specifications, 2003). 그러나, Lee et al.(1996, 1999)과 Bradford(1996)의 최근 연구에서 실제의 설계범위를 갖는 직선이나 곡선 복부판에서 어느 정도의 강성을 갖는 플랜지에 의해서 접하는 변의 경계조건은 단순지지 보다는 고정지지에 더 근접하며, 복부판의 형상비에 따라서는 AASHTO의 탄성좌굴강도가 60%이상 낮게 평가되고 있음을 발표하였다. 특히 강곡선복부판의 전단좌굴강도는 곡률의 영향으로 AASHTO Guide Specifications(2003)의 탄성전단좌굴강도보다 최대 38%이상 증가하고 있음이 Lee and Yoo(1999)의 연구에서 조사되었다. 본 논문에서는 선형좌굴해석을 이용하여 곡률과 경계조건이 동시에 고려된 강곡선 복부판의 전단좌굴계수를 합리적으로 추정할 수 있는 산정식을 제안하고자 한다.

• 한국안전학회지
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• 제17권4호
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• pp.146-152
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• 2002

The steel shows plastic deformation after the yield point exceeds. Because of overloads, the plastic deformation occurs at the interior support of a continuous bridge. The plastic deformation is concentrated at the interior support, and the permanence deformation at the interior support remains after loads pass. Because local yielding causes the positive moment at the interior support, it is called "auto moment". Auto moment redistributes the elastic moment. Because of redistribution, auto moment decreases the negative moment at the interior support of a continuous bridge. In this paper, the moment-rotation curve from Schalling is used. The Plastic rotation is computed by using Beam-line method, and auto moment is calculated based on the experiment curve. The design example is presented using limit state criterion.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.534-539
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• 2001

This paper presents the critical speed analysis of geogrid-reinforced rail roadbeds on soft soil. A rail roadbed on soft ground must be designed to avoid intolerable stress in the underlying soil and to give sufficient support for the rail system. At high speeds, the deformation of rail systems will gain dynamic amplification, and reach excessive values as a certain speed, here termed critical speed is approached. The elastic Winkler foundation model was used to predict the critical speed of geogrid-reinforced rail roadbeds on soft soil and the model properties were determined by the in-situ cyclic plate load test. Based on the parametric study of elastic beam on Winkler foundation model, the critical speed increase with the increase of the flexural risidity of subgrade EI and the stiffness coefficient of Winkler foundation k. From the in-situ cyclic load tests and analysis of elastic beam on Winkler foundation model, the critical speed increase with increase in number of reinforced layer and non-dimensional value for depth of first geogrid layers and the thickness of reinforced rail roadbed u/d.

• 한국정밀공학회지
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• 제27권3호
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• pp.111-117
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• 2010

The repeated unit cell structure is applied to the composite, the carbon nano tube and sandwich panel. In this paper, a study on the stiffness of unit cell structure has been performed with the tube support plate of the steam generator. For this, repeated unit cell structure's equivalent elastic constant and poisson's ratio was evaluated through FEA and tests under the elastic range load. Also we evaluated the effect on the specimen size from results.

• 동력기계공학회지
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• 제21권2호
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• pp.70-76
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• 2017

When Timoshenko arcs considering the shear deformation and rotatory inertia have elastic supports, the authors analyze in-plane free vibration of them by the transfer influence coefficient method. This method finds the natural frequencies of them using the transfer of influence coefficient after obtaining the transfer matrix of arc element from numerical integration of the differential equations governing the vibration of arc. In this study, two computer programs were made by the transfer influence coefficient method and the transfer matrix method for analyzing free vibration of Timoshenko arcs. From numerical results of four computational models, we confirmed that the transfer influence coefficient method is a reliable method when analyzing the free vibration of Timoshenko arcs. In particular, the transfer influence coefficient method is a effective method when analyzing the free vibration of arcs with rigid supports.

• 대한물리의학회지
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• 제5권1호
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• pp.113-123
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• 2010

Purpose : The purpose of this study was to investigate how upper-extremity-movement of PNF(proprioceptive neuromuscular facilitation) with elastic band has effected on arrangement of body and weight-bearing. Methods : The object has worked with 20 patient