The industrialization and urbanization forced to increase the density of pipelines such as water supply, sewers, and gas pipelines. The materials used for the existing pipe lines are mostly composed of concretes and steels, but it is true that the development for more durable and efficient materials has been continued performed to produce long lasting pipe lines. Recently, underground pipes serve in diverse applications such as sewer lines, drain lines, water mains, gas lines, telephone and electrical conduits, culverts, oil lines, etc. In this paper, we present the result of investigation pertaining to the structural behavior of unplasticized polyvinyl chloride (PVC-U) flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, pipe stiffness, 4-point bending test, experimental and analytical studies are conducted. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is about 8% although there are significant variations in the mechanical properties of the pipe material. In addition, it was found by the 4-point bending test there is no problem in the connection between the pipes by coupler.
In this paper, we present the result of analytical investigation pertaining to the structural behavior of steel-concrete composite plate girder with arch-type web stiffener. In the arch-type web stiffener located in the compression side of web, infill concrete is cast to strengthen the arch-type stiffener and also to exert resisting force against compression force. This type of composite steel-concrete plate girder bridge is built and is in service. To understand the behavior thoroughly, analytical parametric study was conducted by using the finite element method. As a result it was found that the effect of arch-type stiffener with infill concrete is considerable for the design of such type composite girder bridge.
Numerical analysis was performed to analysis the structural characteristics of the head device in the road mower system. The head device connects mower system with the boom of the special vehicle. The system with various road surface conditions is subjected to continuous vibration and repeated load. Especially, the maximum equivalent stress occurs in the pillar of the head device, and the maximum equivalent strain also occurs in the fixed plate that supports the mower system. Fatigue analysis results show that the upper end of the pillar is very vulnerable. This analysis results can be used as basic data for optimal road mower head system design.
This study on Structural analysis of kickboard used two types suspension systems. Kickboard is very dangerous in rider because of unstable in diving conditions. Thus suspension system of kickboard are very important component parts. This study focus on two suspensions for stability in kickboard which coil spring and aluminium leaf spring.
현대사회는 조직구성원들의 혁신을 요구하는 지식기반 사회이며, 인적자원의 관리와 혁신이 기업의 경 쟁력을 높이는 중요한 요인으로 작용하고 있다. 이러한 상황에서 기업조직은 구성원들의 혁신을 지향하 는 적극적인 리더십의 발휘를 통해 구성원들의 바람직한 행동을 이끌어 내고, 이를 매개할 수 있는 요인 을 찾기 위한 노력을 해야 한다. 이에 본 연구의 목적은 리더십의 효과성에 대한 연구의 필요성이 제기 되고 있는 리더의 감성지능과 리더의 진정성이 부하의 셀프리더십 및 부하의 혁신행동에 어떠한 영향을 미치는지와 이러한 리더의 감성지능 및 리더의 진정성이 부하의 혁신행동에 미치는 영향력에 대한 부하 의 셀프리더십 매개효과를 검증하기 위한 것이다. 이러한 연구 목적을 위해 부산과 경남의 13개 제조기업 317명의 구성원을 대상으로 실증연구를 실시하였다. 연구결과, 첫째, 리더의 감성지능과 리더의 진정성은 각각 부하의 혁신행동에 긍정적인 정(+)의 영향을 미치고 있음이 확인되었다. 둘째, 리더의 감성지능과 리더의 진정성은 각각 부하의 셀프리더십에 긍정적인 정(+)의 영향을 미치고 있음이 확인되었다. 셋째, 부하들의 셀프리더십이 혁신행동에 유의한 긍정적 정(+)의 영향을 미치고 있음을 검증하였다. 넷째, 리더 의 감성지능과 부하의 혁신행동 간의 관계 및 리더의 진정성과 부하의 혁신행동의 관계에서 부하의 셀프 리더십 매개효과를 검증한 결과, 각 관계별로 부하의 셀프리더십의 매개효과가 있음을 검증하였다. 이는 부하의 셀프리더십이 리더십과 부하의 혁신행동의 관계에 적극적인 영향을 미치고 있음을 알 수 있다. 본 연구는 리더의 감성지능과 진정성이 부하의 셀프리더십을 매개로 부하의 혁신행동에 영향을 주고 있다는 종합적인 새로운 모델을 제시하였다는 이론적 시사점과 조직에서 구성원들의 혁신행동을 강화하 기 위해서는 리더의 감성지능과 진정성, 그리고 부하의 셀프리더십의 역할이 중요하다는 실무적 시사점 을 제공한다. 마지막으로 본 연구의 한계와 향후연구 방향을 제시하였다.
Objective : The main purpose of this study was to analyze the structural relationship among factors that have an impact on Health-Related Quality of Life (HRQOL) in three groups: A stroke patient group (Exp 1), high-risk stroke patient group (Exp 2), and a normal control group.Methods : For this survey, we conducted a secondary analysis using ‘the fifth Korea national health and nutrition examination survey (2010-2011)’, and investigated 2,293 elderly people over 65 years in age.Results :The results were as follows: HRQOL had a significant difference among groups (control›Exp2›Exp1) (p<.05). In the total effect of the experimental 1 groups, their HRQOL was significantly affected by their mental health (β=.425), self-rated health (β=.391), and medical health (β=.290)(p<.05). In the total effect of the experimental 2 group, their HRQOL was significantly by their self-rated health (β=.425), medical health (β =.272), mental health (β=.249), and functional health (β=.234) (p<.05). In the total effect of the control group, their HRQOL was significantly affected by their self-rated health (β=.398) and mental health (β=.184)(p<.05).Conclusion : In conclusion, this study suggested two matters to improve the HRQOL in people with or without a stroke. First, to improve the HRQOL in people suffering from senility, a different approach is needed according to whether the person has had or not had a stoke. Particularly in stroke patients, we should treat both their physical disability and mental health. Second, regardless of whether they have had a stroke, their HRQOL is influenced strongly by their self-rated level of health, and therefore an improvement of HRQOL will be induced by promoting positive health behaviors.
This paper presents on the structural behavior of the the methyl methacrylate monomer (MMA) double wide flanged the glass fiber-reinforced polymer(GFRP) pipe composite structures for the manhole raise. The evaluation of structural performance on this composite structure was conducted by the axial load, fatigue load, and ultimate load test. The assessment indicates that the MMA double wide flanged GFRP pipe composite structures was confirmed safety, durability and reliability in result as expected. It was found that this composite structure was able to short working times to around 30-50% and construction costs to around 10-23% with compare other construction methods. Also, environmental pollution and civil complaints will be prevented because there will be no longer any noises, vibrations, dust, or construction wastes.
In this study we developed an integrated precast concrete decks for a rapid construction. The structural performance in the integrated precast bridge decks is evaluated by real-scale test bed and detailed finite element analyses. The numerical analysis results were compared with the experimental data from a real-scaled single-span precast/prestressed concrete bridge decks under truck loading. Parametric studies are focused on the various effects of external loads on the structural behavior for different locations and measuring points on the precast bridge decks. The assessment in this study indicates that the integrated precast bridge decks show an excellent structural performance as expected.
Various hybrid dampers have been developed as increasing tall buildings in Korea. To minimize the installment space and cost, the new hybrid friction damper was developed using friction components. It is composed of two one-nodal rotary frictional components and a slotted bolted frictional connection. Because of these components, hybrid friction damper can be activated by building movements due to lateral forces such as a wind and earthquake. In this paper, displacement amplitude dependency tests were carried out to evaluate on the structural performance and the multi-slip mechanism of the hybrid damper. Test results show that the multi-slip mechanism is verified and friction coefficients are increasing as displacement amplitudes are increasing.
This paper presents a foundation pile to steel column connection that can resist large magnitude of moment and that can be easy installed. The developed joint has spherical shape and it is given the name HAT joint to mean Hallow half-sphere steel joint. Four types of HAT joints are developed. Namely, H-type, T-type, P-type and K-type. In this paper I will talk about the performance assessment of T-type(Tube Column) and P-type(Pile Column) of HAT joints with finite element analysis and experiment on a full scale model is presented.
Cheomseongdae is the masonry stone structure with the cultural and historical values. But, this structure has the various damages such as cracks, gaps, slope variations and ground subsidence. So, the interests for the safety security in the structural parts have been increased. Therefore, this study performs the structural modelling which considers the several damage cases, and then evaluates the structural behavior characteristics through the discrete element analysis. Especially, this study checks the swelling and displacement gap of the whole structure and the separation between the neighboring members.
Numerical analysis was carried out to investigate the variation of stress and strain characteristics for the rail device in stone board cutting system. The maximum equivalent stress and strain from the vertical load acting on the device decrease as the load moves forward. Also, the maximum equivalent stress appears near the end of left, and the equivalent force of right rail device was about 1.8 times higher than that of left rail device. The variation of stress and strain distributions was remarkable at the edge of the device, and it has a strong influence on the bottom and column. These results can be applicable to optimal design of the stone board cutting device for the system safety.
The chassis frame generally consists of side members, cross beams, and several mounting brackets. Strength and fatigue behaviors of welded joints between members and brackets in a frame are a very complex phenomena, which comes basically due to the structural geometry, non-homogeneous material, and welding residual stresses. Therefore, the prediction of fatigue life for the welded structure is very difficult compared to that for the simple geometry. This paper presents the structural and fatigue analysis results for a body frame and welded joints under system durability loads. In order to fatigue assessment of welded joints, local stress approach is used for its simplicity, which is based on the several empirical S-N curves that are associated with welded joint types and loading modes. The estimated fatigue cycles of the welded areas in a frame were satisfied the target cycles under system load conditions.
A Blast valve is the device that is used in the air intake and the exhaust vent of CBRN(Chemical, Biological, Radiological and Nuclear warfare) protection facility. The valve is automatically closed when explosion pressure is applied from the outside of equipment. This study is investigated on the structural design and the performance of blast valve. After modeling the entire of blast valve and spring assembly, the data for the spring parameter is obtained through the finite element method and the operating limits of the valve are derived. Also, a prototype is made to determine the relationship between the load and the opening closing amount of valve through the load cell test. The performance of prototype at analysis as blast valve is agreed well with that at experiment. It is verified that the blast valve proposed in this paper is designed with the structure to endure the explosion pressure.
GRP pipe (Glass-fiber Reinforced Plastic Pipe) lines making use of FRP (Fiber Reinforced Plastic) are generally thinner, lighter, and stronger than the existing concrete or steel pipe lines, and it is excellent in stiffness/strength per unit weight. In this study, we present the result of field test for buried GRP pipes with large diameter(2,400mm). The vertical and horizontal ring deflections are measured for 387 days. The short-term deflection measured by the field test is compared with the result predicted by the Iowa formula. In addition, the long-term ring deflection is predicted by using the procedure suggested in ASTM D 5365(ANNEX) in the range of 40 to 60 years of service life of the pipe based on the experimental results. From the study, it was found that the long-term vertical and horizontal ring deflection up to 60 years is less than the 5% ring deflection limitation.
The performance enhancement of various structural building systems from natural hazards has become an inctreasingly important issue in engineering field. In this paper, visco-elastic(VE) CST30 damping systems were tested under cyclic loadings to evaluate their performance in terms of ductility and energy dissipation. Main test variables are relative shear stiffness, rate of loading frequency, and thickness of specimens to evaluate the seismic capacity based on the performance criteria. This experiment was performed using a total of 12 specimens, subjected to cyclic loadings up to a shear deformation of 500%. All the CST30 dampers provided a ductile and stable hysterestic behavior when subjected to the demands of large shear stiffness and different loading frequencies. The test results showed that the CST30 dampers are an effective damping systems to enhance the buildings performance for remodeling and retrofit of buildings