• Wind and Structures
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• 제25권1호
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• pp.79-100
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• 2017

The use of wind energy resources is developing rapidly in recent decades. There is an increasing number of wind farms in high wind-velocity areas such as the Pacific Rim regions. Wind turbine towers are vulnerable to tropical cyclones and tower failures have been reported in an increasing number in these regions. Existing post-disaster failure case studies were mostly performed through forensic investigations and there are few numerical studies that address the collapse mode simulation of wind turbine towers under strong wind loads. In this paper, the wind-induced failure analysis of a conventional 65 m hub high 1.5-MW wind turbine was carried out by means of nonlinear response time-history analyses in a detailed finite element model of the structure. The wind loading was generated based on the wind field parameters adapted from the cyclone boundary layer flow. The analysis results indicate that this particular tower fails due to the formation of a full-section plastic hinge at locations that are consistent with those reported from field investigations, which suggests the validity of the proposed numerical analysis in the assessment of the performance of wind-farms under cyclonic winds. Furthermore, the numerical simulation allows to distinguish different failure stages before the dynamic collapse occurs in the proposed wind turbine tower, opening the door to future research on the control of these intermediate collapse phases.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.296-299
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• 2015

돌고래호 사건과 세월호 사건으로 인하여, 선박에서 발생하는 통신에 대한 육지와 구난 시스템과의 비상 통신 문제가 되고 있다. 3면이 바다로 되어 있는 우리나라의 입장에서는 해상 구난과 비상 재난을 위한 연계 통신 시스템에 대한 점검이 필요해졌다. 해상에서 항해하는 선박은 단독으로 재난을 처리해야 하므로 연계 통신 시스템이 보다 완전하게 갖추어 져야 한다. 해상에서 침수되어 침몰하는 선박과 잠수함에 대한 비상 통신에 대한 연구가 필요하다. 육지에서는 해상과 해저의 선박 및 잠수함의 비상 재난에 대비한 육상 연계 통신과 연계 통신 시스템에 대한 연구가 필요하다. 본 논문은 통신 프로토콜과 비상 재난을 대비한 위치 확인 및 육상과 통산을 위한 비행기나 인공위성과의 연계시스템을 연구한다.

• Structural Engineering and Mechanics
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• 제62권4호
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• pp.465-475
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• 2017

Photovoltaic (PV) panels are used in high-rise buildings to convert solar energy to electricity. Due to the considerable energy consumption of high-rise buildings, applying PV technology is of great significance to energy saving. In the application of PV panels, one of the most important construction issues is the connection of the PV panel with the main structures. One major difficulty of the connection design is that the PV panel connection consists of two separate components with coupling and indeterminate dimension. In this paper, the gap element is employed in these two separated but coupled components, i.e., hook and catch. Topology optimization is applied to optimize and design the cross-section of the PV panel connection. Pareto optimization is conducted to operate the optimization subject to multiple load scenarios. The initial design for the topology optimization is determined by the common design specified by the Technical Code for Glass Curtain Wall Engineering (JGJ 102-2003). Gravity and wind load scenarios are considered for the optimization and numerical analysis. Post analysis is conducted for the optimal design obtained by the topology optimization due to the manufactory requirements. Generally, compared with the conventional design, the optimized connector reduces material use with improved structural characteristics.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.210-210
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• 2022

This study evaluates Japan's Official Development Assistance (ODA) projects in Thailand from 2011 to 2013 by deploying the Sendai Framework for Disaster Risk Reduction (SFDRR) and the Organization for Economic Cooperation Development (OECD) evaluation criteria. Special attention is placed on disaster-related development assistance activities of Japan through reviewing long-term impacts of the projects. The Japan International Cooperation Agency (JICA) has played a crucial role in transferring Japan's experiences on disaster risk management to developing countries, including Thailand. The study highlights two flood risk management projects in Thailand with the support of JICA after the 2011 floods, namely the Project for the Comprehensive Flood Management Plan for the Chao Phraya River Basin and the Project for Flood Countermeasures for Thailand Agriculture Sector. The case studies demonstrate that the projects were efficiently and effectively conducted for meeting Thailand's needs and requirements. JICA provided multi-hazards risk analysis through scientific data as well as local knowledge. However, achievements of the project did not last for long because of a lack of Thai stakeholders' commitment and JICA's post-project management. It is concluded that a development agency should consider impacts and sustainability of flood risk management projects more carefully from the stage of planning, and the practical application of the knowledge, and technologies should also be monitored progressively after the completion of the project.

• Earthquakes and Structures
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• 제26권6호
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• pp.489-499
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• 2024

Infill masonry walls are vulnerable to lateral loads, including seismic, wind, and concentrated push loads. Various strengthening metal fittings have been proposed to improve lateral load resistance, particularly against seismic loads. This study introduces the use of post-compressed wedges as a novel reinforcement method for infill masonry walls to enhance lateral load resistance. The resistance of the infill masonry wall against lateral-concentrated push loads was assessed using an out-of-plane push-over test on specimens sized 2,300×2,410×190 mm³. The presence or absence of wedges and wedge spacing were set as variables. The push-over test results showed that both the unreinforced specimen and the specimen reinforced with 300 mm spaced wedges toppled, while the specimen reinforced with 100 mm spaced wedges remained upright. Peak loads were measured to be 0.74, 29.77, and 5.88 kN for unreinforced specimens and specimens reinforced with 100 mm and 300 mm spaced wedges, respectively. Notably, a tighter reinforcement spacing yielded a similar strength, as expected, which was attributed to the increased friction force between the masonry wall and steel frame. The W-series specimens exhibited a trend comparable to that of the displacement ductility ratio. Overall, the findings validate that post-compressed wedges improve the out-of-plane strength of infill masonry walls.

• Wind and Structures
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• 제26권3호
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• pp.163-177
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• 2018

Tornadoes are one of the world's deadliest natural phenomena. They are characterized by short life span and danger. It has been observed through post-damage surveys that localities with large numbers of buildings suffer major damage during a tornado attack resulting in huge loss of life and property. Thus,it is important to study interfering buildings exposed to tornado-like vortices. The present study focuses on external and internal pressures developed on building models exposed to translating tornado-like vortices in the presence of an interfering building model. The effects of translating speed and swirl ratio of a tornado-like vortex on external and internal pressures for a principal building in the vicinity of an interfering building are investigated. Results indicate that external and internal pressures are enhanced or reduced depending on the location of the interfering building with respect to the principal building.

• Geomechanics and Engineering
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• 제8권1호
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• pp.33-52
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• 2015

Based on the Mohr-Coulomb failure criterion, a gradient-dependent plastic model that considers the strain-softening behavior is presented in this study. Both triaxial shear tests on conventional specimen and precut-specimen, which were obtained from an ancient landslide, are performed to plot the post-peak stress-strain entire-process curves. According to the test results of the soil strength, which reduces from peak to residual strength, the Mohr-Coulomb criterion that considers strain-softening under gradient plastic theory is deduced, where strength reduction depends on the hardening parameter and the Laplacian thereof. The validity of the model is evaluated by the simulation of the results of triaxial shear test, and the computed and measured curves are consistent and independent of the adopted mesh. Finally, a progressive failure of the ancient landslide, which was triggered by slide of the toe, is simulated using this model, and the effects of the strain-softening process on the landslide stability are discussed.

• 한국재난정보학회 논문집
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• 제2권1호
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• pp.113-127
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• 2006

The suggestions that follow are about the Qualitative Improvement of private security Industrial. First, in legal and institutional policy, new establishment by law for private security and more support from government is asked. Moreover, the restructuring or M&A between petty companies and the pricing for security service should be performed. Second, in the structural aspect of private security industry, the professional education center for private security guards should be established and the terms of payment and welfare should be improved to the level above standard. In addition, it should be achieved to change the public to have a new and correct understanding of private security and develope the specialized parts suited to the characteristic and ability of each companies. Third, the construction of operating system for private security service should be achieved; recruit system for competent security guards, marketing strategy and enforcement system, widely known confidence to client, normal training system for security guards and post management system for client. This is also to be suited to the characteristic of each companies.

• 대한안전경영과학회지
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• 제1권1호
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• pp.19-28
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• 1999

This paper presents the safety management model, which is appropriate for small-to-medium enterprises that rank the highest disaster rate. It is required for these companies to modify and improve the safety-related articles and it is peformed to compare and analyze the industrial disasters and safety management systems between large enterprises and small-to-medium enterprises. The basic direction of change of industrial safety healthy system must be classified to the dual direction. For large enterprises, it is focused on not pre-regulations but post-regulations based on the self-control safety management system. But for small-to-medium enterprises, it is required to intensify the safety management system and the safety responsibility for owners or administrators. Specially, the responsibility for disaster must be more strengthened by the penalty and the insurance method, and then it must be performed not only the financial support of government but also middle and long-term technical support by private safety organizations.

• Earthquakes and Structures
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• 제7권5호
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• pp.627-645
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• 2014

Using OpenSees as a framework, constitutive models of reinforced, prestressed and prestressed steel fiber concrete found by the panel tests have been implemented into a finite element program called Simulation of Concrete Structures (SCS) to predict the seismic behavior of shear-critical reinforced and prestressed concrete structures. The developed finite element program was validated by tests on prestressed steel fiber concrete beams under monotonic loading, post tensioned precast concrete column under reversed cyclic loading, framed shear walls under reversed cyclic loading or shaking table excitations, and a seven-story wall building under shake table excitations. The comparison of analytical results with test outcomes indicates good agreement.