• Journal of Welding and Joining
• /
• 제33권3호
• /
• pp.62-67
• /
• 2015

A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.

• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제29권2호
• /
• pp.255-279
• /
• 2015

수학과 교육과정에서는 인성 교육을 강조하고 있다. 이에 본 연구에서는 수학교실에서 인성교육을 실현하기 위한 기초 연구를 수행하였다. 본 연구에서는 인성교육의 개념 고찰을 바탕으로 수학수업에서 고려해야할 인성 요인 3가지(이타성 요인, 합리성 요인, 과정지향성 요인)를 추출하였다. 수학교과에서 인성 교육을 위한 수업모형으로 존중적 수행 모형, 독립 수행 모형, 상호주도 모형, 자기주도 모형, 협력중심 모형, 자기이해 모형, 이야기 공감 모형 일곱 가지를 제안하였고, 수업모형에 기초한 교수 학습 자료를 개발한 후 현장 적용을 통해 그 효과성을 검정하였다. 본 연구에서는 교사 설문, 학생 설문, 현장적용에 대한 사전 사후 검사를 통해 수학교과에서도 인성함양을 위한 수학교수학습 실현이 가능하다는 점을 확인하였다.

• 한국전산구조공학회논문집
• /
• 제34권1호
• /
• pp.35-42
• /
• 2021

이 논문에서는 공용중인 구조물의 상시 계측 자료를 사용한 온라인 유한요소 모델 업데이트 방법을 제안한다. 일반적인 최적화 방법에 기반한 기존의 방법은 최적해를 찾기까지 반복적으로 고유치 해석을 수행해야 하므로 상시 업데이트에 사용하기에는 효과적이지 못하다. 제안하는 방법은 별도의 오프라인 작업이나 사용자의 개입이 없이 자동화된 과정으로 계측과 동시에 온라인 유한요소모델 업데이트를 수행할 수 있는 새로운 방법이다. 자동화된 Cov-SSI 알고리즘을 통해 구조물의 진동 계측 신호로부터 고유진동수 및 모드 형상을 식별하고, 이를 다시 역 고유치 신경망에 입력하여 최종적으로 업데이트된 유한요소 모델의 파라미터를 추정한다. 풍하중을 받는 20층 전단 빌딩 구조 모형에 대한 수치예제를 통해 제시한 방법이 자동으로 연속적인 유한요소모델 업데이트를 할 수 있었음을 확인하였다. 또한, 계측 도중 구조물의 특성이 변화하는 시나리오에 대한 예제에서 구조물의 변화가 일어나는 시점과 변화 후 변동된 구조 모델 파라미터 값을 성공적으로 추정할 수 있음을 확인하였다.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
• /
• pp.294-298
• /
• 2008

This is the study to investigate the Algorithm of BRI 2002 which is high level estimation program of smoke movement and phenomenon for performance based of design named 'ROOT C', made by Japan. The aim of this study is that an analytical model is a fire in a three story building. The outline of the building consists of three usual rooms, one on each floor, and an atrium connecting with these rooms.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전기물성,응용부문
• /
• pp.255-258
• /
• 2001

This paper proposes a new structure of a fiber-optic illuminator using high Lux RGB LEDs. A simulation program, LightTools, is used for the verification of the model. An LED mounting holder containing 74 RGB LEDs is used as a basic part of its light collector. Since the light output level of current LED lamps is still far below that of conventional lamps, it is required to double the right output in order to replace a conventional illuminator with a halogen lamp. An additional cone-type reflector is installed hemispherically and the resulting structure comprises a basic collector unit. To further increase the output two collector units are connected together in series. As the result, the light output increases nearly 70% with compared to a collector with a basic structure. The system efficiency can be increased more than 8 times with compared to conventional one.

• Structural Engineering and Mechanics
• /
• 제11권3호
• /
• pp.273-286
• /
• 2001

Viscoelastic (VE) dampers have shown to be capable of providing structures with considerable additional damping to reduce the dynamic response of structures. However, the VE material appears to be sensitive to the variations in ambient temperature and vibration frequency. To minimize these effects, a new VE material has been developed. This new material shows less sensitivity to variations in vibration frequency and temperature. However, it is highly dependent on the shear strain. Experimental studies on the seismic behavior of a 2/5 scale five-story steel frame with these new VE dampers have been carried out. Test results show that the structural response can be effectively reduced due to the added stiffness and damping provided by the new type of VE dampers under both mild and strong earthquake ground motions. In addition, analytical studies have been carried out to describe the strain-dependent behavior of the VE damper. The dynamic properties and hysteresis behavior of the dampers can be simulated by a simple bilinear model based on the equivalent dissipated energy principle proposed in this study.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2000년도 봄 학술발표회논문집
• /
• pp.317-323
• /
• 2000

The purpose of this study is to compare the seismic resistant capacity inherent in ductile moment resisting frames using two different joint modeling. The difference between these two models is the capability for considering the panel zone deformation. For this purpose, 5 story steel moment frame is designed in compliance to the Korean seismic design provisions and the steel structure design standard. Nonlinear Static Procedure(NSP) and Nonlinear Dynamic Procedure(NDP) of this structure are carried out using two different joint models. Based on the results of NSP and NDP, the sensitivity of the response to analytical modeling is appraised. Also, it is proposed that for the highrise steel structures, the joint deformation should be accounted properly by the analytical model.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.319-324
• /
• 2008

In this study the progressive collapse potential of special concentrically braced frames were investigated using the nonlinear static. All of seven different brace types were considered. According to the pushdown analysis results, most braced frames designed according to current design codes satisfied the design guidelines for progressive collapse initiated by loss of a first story mid-column; however most model structures showed brittle failure mode. This was caused by buckling of columns after compressive braces buckled. Among the braced frames considered, the inverted-V type braced frames showed superior ductile behavior during progressive collapse.

• Smart Structures and Systems
• /
• 제16권6호
• /
• pp.1133-1145
• /
• 2015

A new neural network (NN) predictive controller (NNPC) algorithm has been developed and tested in the computer simulation of active control of a nonlinear structure. In the present method an NN is used as a predictor. This NN has been trained to predict the future response of the structure to determine the control forces. These control forces are calculated by minimizing the difference between the predicted and desired responses via a numerical minimization algorithm. Since the NNPC is very time consuming and not suitable for real-time control, it is then used to train an NN controller. To consider the effectiveness of the controller on probability of damage, fragility curves are generated. The approach is validated by using simulated response of a 3 story nonlinear benchmark building excited by several historical earthquake records. The simulation results are then compared with a linear quadratic Gaussian (LQG) active controller. The results indicate that the proposed algorithm is completely effective in relative displacement reduction.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.127-132
• /
• 2007

In this paper, to overcome local damages of structures, an uncertainty of structural model, installing sensors of structures, and economics of building system, decentralized semi-active magnetorheological(MR) damper using the displacement or velocity transferred to the response of floor installed damper is proposed. Relative magnitude between the control force of dampers and the story shear force is difined as design variables and the performance indices response spectra analysis through nonlinear time history analysis excited by seismic loads is performed according to this design variables. And the performance of this decentralized MR damper is compared with previous centralized LQR control algorithm using 3-stories benchmark building structure excited by El Centro (1940, N.S) in order to evaluate the application of building structures.