• 한국융합학회논문지
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• 제6권4호
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• pp.9-14
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• 2015

본 논문은 기타의 목 부분의 형상에 따라 가해지는 힘에 의한 휘어짐의 문제를 해결하기 위한 것으로, 기존의 기타를 보강하여 실제 사용 시, 하중에 취약한 부분을 파악하는 방법을 연구하였다. 본 연구에서는 실제 기타에 적용되는 목재의 물성치를 연구모델에 적용하고 모델링 한 후, 유한요소해석을 수행하였다. 본 논문의 연구를 통해 나온 결과를 사용하여 기존의 기타의 문제로 지적되어온 휨과 파손에 대한 기반자료를 얻을 수 있을 것으로 사료되며 이를 보강 할 수 있는 디자인을 연구하여 그 기타를 개선하고자 한다. 개선된 연구모델에 대한 결과를 토대로 실제 설계에 응용한다면 휨과 파손을 방지하여 내구성을 향상시킬 수 있으며 디자인 면에서의 융합기술로의 접목도 가능하며 미적인 감각을 나타낼 수 있다.

• Geomechanics and Engineering
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• 제11권4호
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• pp.553-570
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• 2016

A series of three-dimensional (3D) parametric finite element analyses have been performed to study the influence of the relative locations of pile tips with regards to the tunnel position on the behaviour of single piles and pile groups to adjacent tunnelling in weathered soil. When the pile tips are inside the influence zone, which considers the relative pile tip location with respect to the tunnel position, tunnelling-induced pile head settlements are larger than those computed from the Greenfield condition. However, when the pile tips are outside the influence zone, a reverse trend is obtained. When the pile tips are inside the influence zone, the tunnelling-induced tensile pile forces mobilised, but when the pile tips are outside the influence zone, compressive pile forces are induced because of tunnelling, depending on the shear stress transfer mechanism at the pile-soil interface. For piles connected to a cap, tensile and compressive forces are mobilised at the top of the centre and side piles, respectively. It has been shown that the increases in the tunnelling-induced pile head settlements have resulted in reductions of the apparent factor of safety up to approximately 43% when the pile tips are inside the influence zone, therefore severely affecting the serviceability of the piles. The pile behaviour, when considering the location of the pile tips with regards to the tunnel, has been analysed in great detail by taking the tunnelling-induced pile head settlements, axial pile forces, apparent factor of safety of the piles and shear transfer mechanism into account.

• 한국터널지하공간학회 논문집
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• 제15권3호
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• pp.345-356
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• 2013

본 연구에서는 SPH(Smoothed Particle Hydrodynamics) 코드를 사용하여 TBM에 장착되는 디스크커터에 의한 암석의 절삭과정을 모사하였다. 이를 위하여 본 연구에서는 3차원 FEM 해석 상용프로그램인 AUTODYN3D를 사용하였으며 이를 통해 국내 황등화강암을 대상으로 총 25개의 절삭조건에 대한 수치적인 절삭시험을 수행하였다. 암석과 디스크커터를 각각 라그란지안 솔버와 SPH 솔버를 사용하여 3차원 형상으로 모델링 하고 두 개의 디스크커터가 순차적으로 암석을 절삭하도록 모델링 하였다. 수치해석과 LCM시험에서 측정한 디스크커터의 작용력은 오차 10%이내의 값을 보여 대체로 일치하는 것으로 나타났고 균열의 전파양상과 암석의 파쇄양상 또한 유사한 것으로 나타났다. 또한 절삭된 최적 커터간격을 측정한 결과 LCM시험 결과와 일치하였다. 이를 통해 SPH코드를 사용한 수치해석기법의 적용성을 확인할 수 있었으나 해석시간을 단축하기 위한 Lagrange-SPH코드의 커플링에 관한 후속연구가 필요할 것으로 판단되었다.

• Earthquakes and Structures
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• 제8권5호
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• pp.1255-1276
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• 2015

The importance of considering soil-structure interaction effect in the analysis and design of RC frame buildings is increasingly recognized but still not penetrated to the grass root level owing to various complexities involved. It is well established fact that the soil-structure interaction effect considerably influence the design of multi-storey buildings subjected to lateral seismic loads. The shear walls are often provided in such buildings to increase the lateral stability to resist seismic lateral loads. In the present work, the linear soil-structure analysis of a G+5 storey RC shear wall building frame resting on isolated column footings and supported by deformable soil is presented. The finite element modelling and analysis is carried out using ANSYS software under normal loads as well as under seismic loads. Various load combinations are considered as per IS-1893 (Part-1):2002. The interaction analysis is carried out with and without shear wall to investigate the effect of inclusion of shear wall on the total and differential settlements in the footings due to deformations in the soil mass. The frame and soil mass both are considered to behave in linear elastic manner. It is observed that the soil-structure interaction effect causes significant total and differential settlements in the footings. Maximum total settlement in footings occurs under vertical loads and inner footings settle more than outer footings creating a saucer shaped settlement profile of the footings. Each combination of seismic loads causes maximum differential settlement in one or more footings. Presence of shear wall decreases pulling/pushing effect of seismic forces on footings resulting in more stability to the structures.

• 한국터널지하공간학회 논문집
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• 제8권2호
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• pp.87-100
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• 2006

본 연구에서는 화강암의 3차원 거동을 예측 분석할 수 있는 구성방정식을 마이크로플레인 모델을 이용하여 Westerly 화강암과 Bonnet 화강암의 시험데이터와 최적을 이루도록 개발하였다. 개발된 마이크로플레인 모델은 화강암의 일축압축 및 삼축압축 거동을 잘 예측하였다. 그리고 개발된 화강암의 마이크로플레인 모델을 유한요소법에 적용하여 암반 굴착시의 발파 모사를 통해 화강암의 비선형 거동을 효과적으로 해석하였다. 발파 응력파의 감쇠계수, 파쇄 영역 그리고 여굴을 방지할 수 있는 화약 장전조건 등이 연구되었다. 마이크로플레인 모델에서는 암석의 비선형 거동 및 균열발생으로 인한 에너지 감소가 잘 반영되었으며 발파 응력파의 감쇠계수는 선형탄성모델보다 크게 계산되었다. 또한 마이크로플레인 모델에서는 발파 응력파 진행에 따른 최대 주변형율을 이용하여 파쇄 영역을 직접적으로 계산할 수 있었다.

• 한국포장학회지
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• 제23권3호
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• pp.183-190
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• 2017

Carton clamp truck is widely perceived as the high-efficient handling equipment of factory premises and warehouse by its capability of palletless handling. Therefore, the significance of a lab-based handling simulation is becoming higher with the growth of clamp truck usage. In this study, preliminary FEA and design of handling test courses for the lab-based simulation of carton clamp truck handling were performed, and the PSD analyses were performed for the modified one for the test course proposed by Park et al. (2017) as well as ASTM D 6055 and ISTA 3B standards. For the vibration in all directions, the vibration energy intensity analyzed by ISTA 3B standard showed higher than that by the other two cases. A FEA was performed for the handling operation of the sudden stop of the clamps after lifting the target HCP (heavyweight refrigerator corrugated package, w=180 kgf) up to the specified height. The slip distance between the clamp arm and the target HCP was 0.85 mm. The simulation result of 0.85 mm was 3.7 times lower than the experimental result (3.2 mm) obtained by Park et al. (2017), and it was estimated that the deviation comes from both the experimental error by weight imbalance of target HCP, and excessive simplification during the FE modelling of target HCP.

• 한국정밀공학회지
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• 제14권8호
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• pp.29-39
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• 1997

The clamp, as the structure which is used for supporting the pipe in the atomic power plant, is produced with a certain degree of anticlastic curvature in the current manufacturing process. In this study, the structural analysis of the clamp and the pipe was performed using ABAQUS. And the finite element modelling for the analysis was made by an HyperMesh. The contact forces which are transferred between the clamp and the pipe for the external force are changed according to the binding force of bolts and keeps the clamp tightly and protects the slipping between the clamp and the pipe. The clamps with the anticlastic curvature and with the flat curvature are considered in order to invest the anticlastic effect. In this study, another case is suggested. The present case does not have the stiffness ring on the end of the clamp but the suggested case has the ring. For the present case, the results showed that the equivalent stress is higher in the anticlastic curvature case than in the flat curvature case and the equivalent stresses on the pipe are almost the same as the binding force increses. For the suggested case, the result showed that the equivalent stress in the anticlastic curvature case decreases until some binding force and increases as the binding forces increase and is lower in some range than in the flat curvature case. From this study, the clamp with the anticlastic curvature in the suggested method is better than the clamp with the flat curvature and the optimal binding force are given.

• Computers and Concrete
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• 제20권5호
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• pp.605-616
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• 2017

Concrete filled steel tubular (CFST) composite girder is a new type of structures for bridge constructions. The existing design codes cannot be used to predict the thermal stress in the CFST truss girder structures under solar radiation. This study is to develop the temperature gradient curves for predicting thermal stress of the structure based on field and laboratory monitoring data. An in-field testing had been carried out on Ganhaizi Bridge for over two months. Thermal couples were installed at the cross section of the CFST truss girder and the continuous data was collected every 30 minutes. A typical temperature gradient mode was then extracted by comparing temperature distributions at different times. To further verify the temperature gradient mode and investigate the evolution of temperature fields, an outdoor experiment was conducted on a 1:8 scale bridge model, which was installed with both thermal couples and strain gauges. The main factors including solar radiation and ambient temperature on the different positions were studied. Laboratory results were consistent with that from the in-field data and temperature gradient curves were obtained from the in-field and laboratory data. The relationship between the strain difference at top and bottom surfaces of the concrete deck and its corresponding temperature change was also obtained and a method based on curve fitting was proposed to predict the thermal strain under elevated temperature. The thermal stress model for CFST composite girder was derived. By the proposed model, the thermal stress was obtained from the temperature gradient curves. The results using the proposed model were agreed well with that by finite element modelling.

• 지질공학
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• 제5권1호
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• pp.31-44
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• 1995

본 연구에서는 지하공동이 해석적용기준을 제시하기 위하여 암반의 역학적 특성과 지하공동에 작용하는 초기응력을 검토하였고, 지하암반을 선형 탄성의 균질한 암석으로 가정하여 공동주위의 거동을 검토하였으며, 그 결과를 요약하면 다음과 같다. - 지하암반공동의 유한요소경계는 공동의 중심으로 부터 공동 반지름의 6배이상으로 하여야 한다. - 원형공동의 경우, 수직응력과 수평응력의 비인 $K_0$ 값이 증가함에 따라 공동측면에서는 변형이 공동의 중심방향으로 증가하고, 공동상부에서는 공동의 중심방향으로 변형이 감소한다. 또한 $K_0$ 값이 1/4보다 작을 경우 공동주변암반체에서 인장영역이 발생함을 알 수 있었다. - 마제형인 공동 I과 Powerstation 형인 공동 II에 발생하는 변위는 원공동과 거의 비슷한 경향을 나타내고, 공동 I, II에 발생하는 응력집중은 공동의 벽면과 바닥으 교차부에서 발생하며, 공동 II에서 보다 큰 응력집중이 발생함을 알 수 있었다.

• 센서학회지
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• 제15권1호
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• pp.34-39
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• 2006

This study provides the electrical model of combustible catalytic gas sensor. Physical characteristics such as thermal behavior, resistance change were included in this model. The finite element method analysis for sensor device structure showed that the thermal behavior of sensor is expressed in a simple electrical equivalent circuit that consists of a resistor, a capacitor and a current source. This thermal equivalent circuit interfaces with real electrical circuit using two parts. One is 'power to heat' converter. The other is temperature dependent variable resistor. These parts realized with the analog behavior devices of the SPICE library. The gas response tendency was represented from the mass transferring limitation theory and the combustion theory. In this model, Gas concentration that is expressed in voltage at the model, is converted to heat and is flowed to the thermal equivalent circuit. This model is tested in several circuit simulations. The resistance change of device, the delay time due to thermal capacity, the gas responses output voltage that are calculated from SPICE simulations correspond well to real results from measuring in electrical circuits. Also good simulation result can be produced in the more complicated circuit that includes amplifier, bios circiut, buffer part.