• 한국지반신소재학회논문집
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• 제13권4호
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• pp.97-107
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• 2014

본 논문에서는 표준트럭하중을 받는 연약지반에 놓인 롤타입 강재매트의 모델링과 해석을 수행하였다. 롤 타입 강재매트는 접근성이 제한된 동토지역에서 손쉬운 현장운반을 위해 원형으로 접을 수 있는 강재매트를 의미하며, 동토지반의 융해로 형성되는 연약지반을 통과하는 비포장도로의 급속보강을 위해 개발되었다. 해석 모델은 강재매트 연결부의 비선형적 거동특성을 모사할 수 있는 연결요소, 강재매트의 휨강성을 갖는 쉘요소, 지반특성을 고려한 스프링 구속으로 구성된다. 또한 각 해석요소들의 구조적 거동은 각 모델링 단계에서 실험과 해석을 통해 검증되었다. 링크요소가 없는 빔과 쉘 요소해석이 수행되었으며, 본 연구에서 제시된 해석모델의 결과와 비교하였다. 해석결과, 본 연결부를 고려한 쉘 해석모델의 수직 처짐 결과가 다른 모델에 비하여 상당히 큰 것으로 확인되었다. 따라서, 느슨한 모래지반에 놓인 롤 타입 강재매트의 해석모델은 면밀한 변수해석 연구에 근거하여야 함을 알 수 있다.

• 한국농공학회지
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• 제30권2호
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• pp.67-81
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• 1988

The purpose of the present study is to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir and to establish a solid foundation for the automatic optimum structural design combined with finite element analysis. The major design variables are the dimensions and steel areas of each member of the structures. The construction cost which is composed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of the working stress design method. The corresponding design guides including the standard specification for concrete structures have been also employed in deraving the constraint conditions. The present nonlinear optimization problem is solved by SUMT method. The reinforced concrete intake-tower is decomposed into three major substructures. The optimization is then conducted for both the whole structure and the substructures. The following conclusions can be drawn from the present study. 1. The basis of automatic optimum design of reinforced concrete cylindrical shell structures which is combined with finite element analysis was established. 2. The efficient optimization algorithms which can execute the automatic optimum desigh of reinforced concrete intake-tower based on the working stress design method were developed. 3. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optImization algorithms developed in this study seem to be efficient and stable. 4. The difference in construction cost between the optimum designs with the substructures and with the entire structure was found to be small and thus the optimum design with the substructures,rnay conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the tensile stress insteel for salb, the minimum lonitudinal steel ratio constraints for tower body and the shearing stress in concrete, tensile stress in steel and maximum eccentricityconstraints for footing, respectively. 6. The computer program develope in the present study can be effectively used even by an unexperienced designer for the optimum design of reinforced concrete intake-tower.

• 한국전산구조공학회논문집
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• 제33권4호
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• pp.245-253
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• 2020

본 논문은 모노파일 풍력 지지구조물에 대한 공진 안전성 평가에서 여러 말뚝-구조물 상호작용(PSI) 모델을 사용하여 고유진동수를 비교하였다. PSI 재현을 위한 유한요소모델은 기저 스프링 모델, 분산 스프링 모델, 3차원 고체-쉘 모델을 사용하였다. PSI 모델이 고유주파수에 미치는 영향을 분석하기 위해 기저 스프링과 분산 스프링 모델 적용을 위한 강성행렬 산정법과 Winkler 보 모델을 각각 논문에 나타내고 이들 모델로부터 도출된 서로 다른 기하 및 지반조건을 갖는 모노파일의 고유진동수를 조사하였다. 해석결과는 또한 3차원 고체-쉘 모델의 고유진동수와도 비교되었다. 해석결과는 소구경 모노파일이 견고한 지반 및 암반에 관입된 경우 각 해석모델로부터 얻어진 고유진동수의 차이가 거의 없음을 보여준다. 반면 연약 지반에 설치된 대구경 모노파일에 대해 분산스프링 모델은 고유진동수를 과대평가할 수 있다. 따라서 고유진동수 평가 시 구조물 규모와 지반 조건을 고려해 적합한 PSI모델이 적용되어야 한다.

• 한국지진공학회논문집
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• 제26권2호
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• pp.71-82
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• 2022

This paper presents the effect on the inelastic behavior and structural performance of concrete and filled steel pipe through a numerical method for reliable judgment under various load conditions of the CJS composite structural system. Variable values optimized for the CJS synthetic structural system and the effects of multiple variables used for finite element analysis to present analytical modeling were compared and analyzed with experimental results. The Winfrith concrete model was used as a concrete material model that describes the confinement effect well, and the concrete structure was modeled with solid elements. Through geometric analysis of shell and solid elements, rectangular steel pipe columns and steel elements were modeled as shell elements. In addition, the slip behavior of the joint between the concrete column and the rectangular steel pipe was described using the Surface-to-Surface function. After finite element analysis modeling, simulation was performed for cyclic loading after assuming that the lower part of the foundation was a pin in the same way as in the experiment. The analysis model was verified by comparing the calculated analysis results with the experimental results, focusing on initial stiffness, maximum strength, and energy dissipation capability.

• 한국전산구조공학회논문집
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• 제19권3호
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• pp.271-282
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• 2006

지반위에 놓인 콘크리트 슬래브가 온도하중을 받을 때 지반의 전단저항과 슬래브 하부와 지반과의 마찰 등에 의해 생기는 슬래브 하부의 수평저항을 고려하여 지반위에 놓인 콘크리트 슬래브의 거동을 분석하였다. 지반위의 콘크리트 슬래브와 강성도로포장의 해석에 널리 사용되는 탄성지반위의 얇은 판을 이용하여 슬래브 하부의 수평저항을 고려하기 위한 해석 공식을 유도하였다. 이를 이용하여 판요소와 쉘요소를 이용한 유한요소법에 의한 모델을 개발하여 수치해석 결과를 도출하였다. 해석 공식과 수치해석 모델을 이용한 해석 결과를 비교 분석하였고 매우 비슷한 결과가 도출 되는 것을 알 수 있었다. 슬래브의 상부와 하부에 온도 차이가 있을 때와 슬래브의 온도가 전체적으로 감소할 때, 콘크리트 슬래브의 응력 분포에 슬래브 하부의 수평저항이 미치는 민감성을 여러 가지의 다른 슬래브의 두께, 탄성계수, 그리고 지반의 수직탄성계수 등을 고려하여 분석하였다. 해석 결과에서 온도하중을 받을 때 슬래브 하부의 수평저항은 슬래브의 응력에 매우 큰 영향을 미칠 수 있다는 것을 발견하였다.

• 대한한방소아과학회지
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• 제13권1호
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• pp.63-138
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• 1999

From all possible chinese medical literatures, I studied the history of chinese pediatrics by dividing into Chunqiu Zhanguo, QinHan dynasties, LiangJin, SuiTang five dynasties, Song Dynasty, Jin and Yuan dynasties, Ming Qing dynasties. The conclusions are summarized as followings 1. The mentions related with pediatrics existed already in Yan ruins turtle shell letters, and 〈Yellow Emperor's classic of internal medicine> in Chunqiu Zhanguo time formed the system of medicine, established the theoretical foundation. 2. Chang Ji established the system of diagnosis and treatment based on overall analysis of symptoms and signs in , and later pediatricians commonly applied his prescriptions to the febrile diseases. 3. The period from LiangJin to SuiTang, Pediatrics was established as special department then in , Chao Yuanfang stated the etiology, pathogenesis, symptomatology of pediatric diseases. 4. In Song dynasty. pediatric 4 major, symptoms that had been mentioned from SuiTang dynasties, were clearly established, pediatrical special books were published, and written by Qian Yi who is considered as the founder of chinese pediatrics, established the foundation of pediatrical division formation in distinction from adult fields. 5. In Jin and Yuan dynasties, four eminent physicians established the actual relationship between the theories and practical applications and insisted various and creative theories based on the classical medicine, for example, the theory that fire and heat in the body was the main cause of diseases of Liu Wansu purgation theory of Zhang Congzheng, qi regulating theory of Liu Gao, ministerial fire theory and the theory that yang is ever in excess while Yin is ever deficient of Zhu Zhenheng, etc, and they applied those theories to pediatrical various sides. 6, In Ming Qing dynasties, pediatrical specialists and pediatrical publications had increased, eg, father and son Xue Kai Xue Ji, Wan Quan, Lu Bai-si, etc in Ming dynasty, Ye Gui, Chen Fuzheng, Xia Ding, etc in Qing dynasty were famous as pediatricians. Specially, the doctrine of epidemic febrile diseases at that time showed prominent effects to children's epidemic febrile diseases.

• Steel and Composite Structures
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• 제43권1호
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• pp.91-106
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• 2022

This paper has focused on presenting a three dimensional theory of elasticity for free vibration of 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) cylindrical panels resting on two-parameter elastic foundations. The elastic foundation is considered as a Pasternak model with adding a Shear layer to the Winkler model. The porous graphene foams possessing 3D scaffold structures have been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the shell thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. Three complicated equations of motion for the panel under consideration are semi-analytically solved by using 2-D differential quadrature method. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Because of using two-dimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary at the curved edges. It is explicated that 3D-GrF skeleton type and weight fraction can significantly affect the vibrational characteristics of GrF-PMC panel resting on two-parameter elastic foundations.

• 한국강구조학회 논문집
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• 제25권3호
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• pp.307-320
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• 2013

기존 해상풍력발전 지지구조물의 단점을 보완한 신형식의 파일 기초 하이브리드 지지구조물을 본 연구에서 제안하였다. 이 지지구조는 콘크리트 자중을 이용한 중력식 기초의 개념으로부터 수정되어 4개의 파일로 지지되며, 강재 샤프트와 원추형 콘크리트가 결합된 하이브리드 형식이다. 규모가 크고 두꺼운 콘크리트의 3차원 해석을 위해, 정확한 기하형상 모델링과 응력의 절점 보간이 가능한 솔리드-쉘 입체요소를 개발하였다. 해양구조물 전용 유한요소 프로그램인 XSEA에 탑재된 솔리드-쉘 요소와 Stream Function 파랑 이론을 적용하여, 제안한 하이브리드 지지구조물에 대해 서남해안 지역의 환경조건을 적용한 준정적 해석 및 고유진동수 해석을 실시하였다. 해석결과, 수평변위가 허용변위 이내로 나타났고, 고유진동수 해석을 통해 하이브리드 구조형식의 동적거동에 대한 우수성을 입증하였다. 결과적으로, 파일지지 하이브리드 지지구조물은 우리나라 서남해안 지역과 같이 연약지반에 적용 할 수 있는 충분한 안정성을 가진 것으로 평가 되었고, 각 부재에 대한 최적화 연구를 통해 경제성 확보가 가능한 것으로 검토되었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제1권2호
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• pp.155-159
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• 2000

In the spring silkworm rearing period of year 1998, some nutritional aspects were studied in the Agricultural Research Station of the Komotini town in Greece, to investigate the feeding behaviour of some Bulgarian silkworm hybrids, suitable for spring rearing, during the fourth and fifth instal under the local climatic conditions. The silkworms were fed by locally cultivated Japanese Kinriu mulberry (Morus alba L.) variety leaves. Eight Bulgarian hybrids had been used, namely Vratza-53xVratza-52, Ukraine-20xVratza-53, Super 1xHessa 2, Merefa 2xVratza 35, as well as their reciprocal crosses. The studies showed out a remarkably higher feed intake and feed utilization by the hybrids Hessa 2xSuper-1, Merefa 2xVratza 35 and Vratza-52xVratza-53. The same hybrids showed an efficient food utilization by means of daily growths cocoon shell ratio and raw silk output. In terms of food to silk conversion efficiency Hessa 2xSuper-1 hybrid gave the best results. Larval stage duration for fourth and fifth instar was not affected by feed intake and utilization. All hybrids showed a good adaptation to the local environment and their feeding performance was equal to the international existing standards. All calculated parameters were found to be around the mean values of other up to date presented results and thus considered as acceptable for the needs of the local production.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1221-1230
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• 2008

Inflatable rubber dams are used for controlling flood, impounding water for recreations, preventing beach erosions, diverting water for irrigations, and generating hydropower. They are long, flexible, inflated with air, cylindrical structures on a rigid horizontal foundation such as concrete. The dam is modeled as an elastic shell inflated with air. The mechanical behaviors of the inflated dam model were investigated by using the finite element method. The analysis process such as One Way Coupling Fluid-Structure Interaction consists of two steps. First, the influences of the fluid side were investigated, viz, the shape changes of the inflated rubber dam due to the fluid motions was captured when the height of the dam was 30cm with air pressure 0.01MPa, at which the pressure distributions over the surface of the dam were calculated. And next, the structural deformations were calculated using the pressure distributions. The initial inlet velocity for flow field was set to 0.1m/s. The structural deformation behaviors were investigated. The final research goal is to develop a Korean Inflatable Rubber Dam to be used for generating small hydropower.