• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.880-887
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• 2020

This study was conducted to investigate the running stability of a high-speed train operated in a tunnel and an open field when external forces such as wind pressure and train crossings were applied to the vehicle. With no external force, the running stability at 400 km/h was examined, and the wheel weight reduction ratio, lateral pressure of the axles, and derailment coefficient satisfied the criteria of the technical standards for a high-speed train. When the distance between the centers of the tracks is 4.6 m, the external force caused by train crossing slightly affects the lateral acceleration of the vehicle but does not significantly affect the wheel weight reduction rate, lateral pressure, and derailment coefficient in a tunnel and open filed. When the distance is 4.6~5.0 m, the wheel weight reduction ratio, lateral pressure, and derailment coefficient satisfy the criteria with 20 m/s wind. When the wind speed was 30 m/s, the derailment coefficient satisfied the criteria, and the other variables exceeded them. It is predicted that a high-speed train can be operated safely at 400 km/h with wind speed of up to 20 m/s, and it should be slowed down at a wind speed of 30 m/s.

• Wind and Structures
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• v.25 no.5
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• pp.493-506
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• 2017

Wind-induced response behavior of long-span roof structures is very complicated, showing significant contributions of multiple vibration modes. The largest load effects in a huge number of members should be considered for the sake of the equivalent static wind loads (ESWLs). Studies on essential matters and necessary conditions of the universal ESWLs are discussed. An efficient method for universal ESWLs on long-span roof structures is proposed. The generalized resuming forces including both the external wind loads and inertial forces are defined. Then, the universal ESWLs are given by a combination of eigenmodes calculated by proper orthogonal decomposition (POD) analysis. Firstly, the least squares method is applied to a matrix of eigenmodes by using the influence function. Then, the universal ESWLs distribution is obtained which reproduces the largest load effects simultaneously. Secondly, by choosing the eigenmodes of generalized resuming forces as the basic loading distribution vectors, this method becomes efficient. Meanwhile, by using the constraint equations, the universal ESWLs becomes reasonable. Finally, reproduced largest load effects by load-response-correlation (LRC) ESWLs and universal ESWLs are compared with the actual largest load effects obtained by the time domain response analysis for a long-span roof structure. The results demonstrate the feasibility and usefulness of the proposed universal ESWLs method.

• Wind and Structures
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• v.31 no.4
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• pp.335-350
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• 2020

In coastal residential communities, especially along the coastline, flooding is a frequent natural hazard that impacts the area. To reduce the adverse effects of flooding, it is recommended to elevate coastal buildings to a certain safe level. However, post storm damage assessment has revealed severe damages sustained by elevated buildings' components such as roofs, walls, and floors. By elevating a structure and creating air gap underneath the floor, the wind velocity increases and the aerodynamics change. This results in varying wind loading and pressure distribution that are different from their slab on grade counterparts. To fill the current knowledge gap, a large-scale aerodynamic wind testing was conducted at the Wall of Wind experimental facility to evaluate the wind pressure distribution over the surfaces of a low-rise gable roof single-story elevated house. The study considered three different stilt heights. This paper presents the observed changes in local and area averaged peak pressure coefficients for the building surfaces of the studied cases. The aerodynamics of the elevated structures are explained. Comparisons are done with ASCE 7-16 and AS/NZS 1170.2 wind loading standards. For the floor surface, the study suggests a wind pressure zoning and pressure coefficients for each stilt height.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.325-328
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• 2006

This study analyzed the fluid state around a container crane according to a wind direction when a wind load was applied to a container crane. The container crane for this research is a model of a 50-ton class used broadly in the current ports. The dimension of an external fluid field is $500m{\times}200m$. This study considered the change of a wind velocity according to an altitude in a criterion of a wind velocity, 50m/s, applying a power series law. An incident angle applied to an interval of 30 degrees in $0^{\circ}C$ ${\sim}$ $180^{\circ}C$ and this study carried out a computation fluid dynamics using a CFX 10. In this study, we indicate the wind pressure and coefficient according to the height and section figure of each member. In addition, we suggest the wind load according to a wind direction.

• Journal of Navigation and Port Research
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• v.39 no.5
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• pp.385-391
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• 2015

In offshore, various external forces such as wind force, tidal current and impulsive breaking wave force act on offshore wind tower. Among these forces, impulsive breaking wave force is especially more powerful than other forces. Therefore, various studies on impulsive breaking wave forces have been carried out, but the soil reaction are incomplete. In this study, the p-y curve is used to calculate the soil reaction acting on the offshore wind tower when an impulsive breaking wave force occurs by typhoon. The calculation of offshore wind tower against impulsive breaking wave force is applied for the multi-layered soil. The results obtained in this study show that although the same wave height is applied, the soil reaction generated by impulsive breaking wave force is greater than the soil reaction generated by wave force.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.1
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• pp.20-27
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• 2003

The FPSO is moored by mooring lines to keep the position of it. The nonlinear motion analysis of the moored FPSO must be carried out in the initial design stage because sea environments affect motion of it. In this paper, the mathematical model is based on the slow motion maneuvering equations in the horizontal plane considering wave, current and wind forces. The direct integration method is employed to estimate wave loads. The current forces are calculated by using mathematical model of MMG. The turret mooring forces are quasi-statically evaluated by using the catenary equation. The coefficients of a model for wind forces are calculated from Isherwood's experimental data and the variation of wind speed is estimated by wind spectrum according to the guidelines of API-RP2A. The nonlinear motions of FPSO are simulated under external forces due to wave, current, wind including mooring forces in time domain.

• Journal of Ocean Engineering and Technology
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• v.32 no.1
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• pp.62-67
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• 2018

A wave buoy commonly used for measurements in marine environments is very useful for measurements on the sea surface wind and waves. However, it is constantly exposed to external forces such as typhoons and the risk of accidents caused by ships. Therefore, the installation and maintenance charges are large and constant. In this study, we developed a system for monitoring the sea surface wind using marine radar to provide spatial and temporal information about sea surface waves at a small cost. The essential technology required for this system is radar signal processing. This paper also describes the analytical process of using it for monitoring the sea surface wind. Consequently, developing this system will make it possible to replace wave buoys in the near future.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.20-26
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• 2008

The nacelle cover and nosecone are made of composite materials, especially the stiffener is added in the nacelle cover in order to enhance it's stiffness. The nacelle cover consists of all three covers of left, right side cover and upper cover and each cover is connected with bolts. Also, the nacelle cover and nacelle frame are connected with bolts. The nacelle cover and nosecone have a important role to prevent the components of nacelle and rotor from external circumstances such as snow, rain and wind. Therefore, it is necessary to analyze and evaluate the strength and deformation for them in the design level. According to GL Wind Specifications, this paper shows the results that nacelle cover of 2MW wind turbine satisfy the strength and deformation throughout analysis using Patran/Nastran programs.

• Journal of the Korean Institute of Rural Architecture
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• v.12 no.2
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• pp.23-29
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• 2010

Vinyl house is a simple agricultural structure that is installed economically and easily. In contrast, every year the farmers have spent a lot of money because of the collapse of this structure caused by the external forces such as strong wind and heavy snow. To prevent this damage due to frequent heavy snow and strong wind, it would be necessary to design it again. But getting rid of former vinyl house and reconstructing is unreasonable. It would be very economic if the former vinyl house is strengthened simply. This paper covers the investigation of the effect of the bracing systems that are additionally inserted inside the ordinary single frames as well as unbraced multiple frames that resisting only the strong wind load.

• International Area Studies Review
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• v.21 no.1
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• pp.281-301
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• 2017

This article examines the way of the functionality of policy instruments for the development of renewable energy through the case of the wind power. The general barrier of the renewable energy development is considered to be the economic barrier. However the principal issue is the political barrier without the broad cooperation between the host government and the firm. Maintaining the long-term competitive advantage requires the shift of not only the strategy following the external circumstance but also the internal capacity development to utilize resources. Thus the comparative case study of Sri Lanka and Germany proposes the analysis of the supply-push and demand-pull policy with five patterns on the development of wind power in order to suggest how the functionality of policy instruments must be served to foster the wind power.