• 국제강구조저널
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• 제18권4호
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• pp.1373-1383
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• 2018

Experimental study was conducted to investigate the seismic behavior of roof joint. Eight full-scale specimens were tested considering the effects of axial force, joint height, hole shape of base plate and edge distance of concrete on the failure mode and resistance capacity of roof joint. With the increase of axial force, the hysteretic curves were fuller. The mechanical model of roof joint change from bending to shear. With the increase of joint height, the ultimate strength of roof joint decreased. If the hole shape of base plate changed from circle to loose, the slip behavior of roof joint appeared and the ultimate strength of roof joint decreased. The damage of edge concrete may occur if the edge distance of concrete was not big enough.

• Journal of Welding and Joining
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• 제13권1호
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• pp.138-144
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• 1995

Recently, as the industrial structure tends to become large, the thickness of structural plate becomes thicker. Therefore, the thicker the plate of welded structure is, the larger the shape of welded joint. The effect of large heat input makes large heat affected zone(HAZ). These bring to complict welding residual stress and to weaken material, which may cause extremely harm to the safety of structures. Nevertheless, welding is design is regulated by the KS, JIS or standard in the resister of shipping such as KR, ABS or LR. However, these rules are based on rather experimental than theoretical. In this study, the computer program of heat conduction, considering un-steady state and quasi-steady state, is developed for optimizing(minimizing) a shape of welded joint. The characteristics of heat on the welded joints with various shapes are clarified by the results of the analyses.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.1-15
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• 1998

Currently, computational analysis is a popular technology in automobile engineering. Finite element analysis is an excellent method for body analysis. For finite element analysis, accurate modeling is very important to obtain precise information. Stick modeling is a convenient way in that it is easy and simple. When a stick model is utilized, the joints are modified in the tuning process. A tuning method for the joint has been developed. The joints are modeled by designated beam elements. An optimization method called "Goal Programming" is employed to impose the target values. With the tuned joints, the entire optimization has been carried out. Using the "Recursive Quadratic Programming" algorithm, the optimization process determines the configuration of the entire structure and sizes of all the sections. For example, the structure of an electrical vehicle is modeled and analyzed by the method. The stick model works well since the structure is made of aluminium frames. Although the example handles an electrical vehicle, this method can be applied to general vehicle structures.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.298-303
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• 1998

Most of mechanical structures are combined of substructures such as beam and/or plates. There are few system with unibody structures but are not a few systems with united body structures. Generally the dynamic analysis of whole structures is perform ed under alternating load. However, the analysis of each joint area is more important than others for zero severity. This paper presents the results of analysis of concentration stress in bolt jointed structure with variable preload. At frist, a static vibration test was performed to find out a nominal stress of bolt joint ed plates from the relationship between natural frequency and nominal stress. Then a concentration stress was computed at contact point between bolt and plate in the structure. It is believed that the proposed method has promising implications for safer design with fatigue quality index of stress concentration factor and has merit for cost down and saving time at the beginning of vehicle development.

• International Journal of Aerospace System Engineering
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• 제8권2호
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• pp.1-3
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• 2021

This study proposed a specific preliminary structural design procedure of the main wing for a small scale WIG vehicle to meet the target weight of the system requirement. The high stiffness and strength Carbon-Epoxy material was used for lightness, and the foam sandwich type structure at the upper skin and the spar webs was adopted for improvement of structural stability. After structural design, wing joint part was designed. Through investigation on structural design result, design modification was performed. After design modification, even thought the designed wing weight was a little bit heavier than the target wing weight, the structural safety and stability of the final design feature was confirmed.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.4-5
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• 2021

In this study, in the coating-sheet composite waterproofing method, a specimen was formed to prevent the transmission of the no-node tensile stress occurring under the junction between sheets by forming an insulating structure when the junction was formed, and to compare the effect of preventing breakage with the existing common junction. For this, tensile performance evaluation was conducted. As a result of the evaluation, it was confirmed that it exhibited higher tensile strength compared to the existing joint and at the same time exhibited a large width of displacement characteristics, and thus, had an effect of preventing breakage.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.58-63
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• 2009

Biaxial compression test was conducted on a transversely isotropic synthetic jointed rock model for the understanding of the fracture behaviors of a sedimentary or metamorphic rocks with well developed bedding or foliation in uni-direction. The joint angles employed for the model are 30, 45, and 60 degrees to the horizontal, and the synthetic rock mass was made of early strength cement. From the biaxial compression test, initiation propagation of tensile cracks at norm to the joint angle was found. The propagated tensile cracks eventually developed rock blocks, which was dislodged from the rock mass. Furthermore, the propagation process of the tensile cracks varies with joint angle: lower joint angle model shows more stable and progressive tensile crack propagation. The experiment results were validated from the simulation by using discrete element method PFC 2D. From the simulation, as has been observed from the test, a rock mass with lower joint angle produces wider damage region and rock block by tensile cracks. In addition, a rock model with lower joint angle shows a progressive tensile cracks generation around the opening from the investigation of the interacted tensile cracks.

• Smart Structures and Systems
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• 제5권4호
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• pp.329-344
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• 2009

Ultrasonic chaotic excitations combined with sensor prediction algorithms have shown the ability to identify incipient damage (loss of preload) in a bolted joint. In this study we examine a physical experiment on a single-bolt aluminum lap joint as well as a three-dimensional physics-based simulation designed to model the behavior of guided ultrasonic waves through a similarly configured joint. A multiple bolt frame structure is also experimentally examined. In the physical experiment each signal is imparted to the structure through a macro-fiber composite (MFC) patch on one side of the lap joint and sensed using an equivalent MFC patch on the opposite side of the joint. The model applies the waveform via direct nodal displacement and 'senses' the resulting displacement using an average of the nodal strain over an area equivalent to the MFC patch. A novel statistical classification feature is developed from information theory concepts of cross-prediction and interdependence. This damage detection algorithm is used to evaluate multiple damage levels and locations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.871-873
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• 1995

The purpose of this paper is to design and construct the compact type joint driver and controller of the biped robot. This biped robot will be designed to be suitable for the practical usages and applications in the work environment, which is not plat floor, like a stairs by taking the stand-alone style that equipped all the parts except power sources. Generally, highly nonlinear motion dynamics of the biped robot is realized to linear approximations by installing a high-ratio speed reducer at each joint and dividing motions into a several piecewise linear motions, which is realized by the digital controller design techniques. This biped robot has symmetrical structure to get the stable walking ability and also the hierachical structure to control each joint as well. That is, all of the joint controllers are connected to the main controller in the composition of overall controllers. The driver and controller of each joint uses PI controller that compensate the velocity and position errors by the data of the encoder. And the signal characteristics of each joint controller forms a trapezoid speed profile which is predefined by the values of direction, maximum velocity and position.

• International Journal of Ocean System Engineering
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• 제2권2호
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• pp.82-91
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• 2012

Fillet welding is widely used in the assembly of ships and offshore structures. The T-joint configuration is frequently reported to experience fatigue damage when a marine structure meets extreme loads such as storm loads. Fatigue damage is affected by the magnitude of residual stresses on the weld. Recently, many shipping registers and design guides have required that the fatigue strength assessment procedure of seagoing structures under wave-induced random loading and storm loading be compensated based on the effect of residual stresses. We propose a computational procedure to analyze the residual stresses in a T-joint. Residual stresses are measured by the X-ray diffraction (XRD) method, and a 3-D finite element analysis (FEA) is performed to obtain the residual stress profile in the T-joint. The proposed finite element model is validated by comparing experiments with computational results, and the characteristics of the residual stresses in the T-joint are discussed.