• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.35-40
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• 2002

In the present study, we examined the influence of prestrain on creep strength of Class M alloy(STS310S) and Class A(STS310J1TB) alloys containing precipitates. Prestrain was given by prior creep at a higher stress than the following creep stresses. Creep behaviour before and after stress change and creep rate of pre-strianed specimens were compared with that of virgin specimens. Pre-straining produced the strain region where the strain rate was lower than that of a virgin specimen both for STS310J1TB and STS310S steels. The reason for this phenomenon was ascribable to the viscous motion of dislocations, the interaction between dislocations and precipitates in a STS310J1TB steel, and the interaction of dislocations with sub-boundaries in a STS310S steel which has the higher dislocation density and smaller subgrain size resulted from pre-straining at higher stress.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.768-777
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• 2005

This paper shows that the performance of a nonlinear fluid engine mount can be improved by an optimal design process. The property of a hydraulic mount with inertia track and decoupler differs according to the disturbance frequency range. Since the excitation amplitude is large at low excitation frequency range and is small at high excitation frequency range, mathematical model of the mount can be divided into two linear models. One is a low frequency model and the other is a high frequency model. The combination of the two models is very useful in the analysis of the mount and is used for the first time in the optimization of an engine mount in this paper. Normally, the design of a fluid mount is based on a trial and error approach in industry because there are many design parameters. In this study, a nonlinear mount was optimized to minimize the transmissibilities of the mount at the notch and the resonance frequencies for low and high-frequency models by a popular optimization technique of sequential quadratic programming (SQP) supported by $MATLAB^{(R)}$subroutine. The results show that the performance of the mount can be greatly improved for the low and high frequencies ranges by the optimization method.

• Journal of the Korean Institute of Rural Architecture
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• v.11 no.3
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• pp.11-18
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• 2009

The purpose of this paper is to find out the investigation of overseas case in Street Furnitures of Public Design. Thus this research regions select among the waterfront cities; Tokyo/Yokohama(Japan), Nies/Cannes(France), Shanghai(China), Vancouver(Canada), in addition to the city of art and romance; Paris. Above all, it is necessary to study concept of public design and definition of street furnitures. The survey data collected from forenamed cities and the items of street furnitures are various installments such as kiosk, bench, bollard, litter-bin, sign board, toilet, bus/taxi station, fence, shelter, lighting column, fountain, telephone-booth, clock-tower, automaton, bicycle stand, playing object etc. In this study street spaces are analysed that is related to regional surroundings and pedestrian's culture. Consequently, design trend of street furniture in foreign case analysis are going into thoroughly modern image as well as checking of form, color, material and maintenance system. According to the above findings, this paper will provide basic data for establishing of the street furniture and improving of public design to the regional citizen, local government officials and regional experts.

• Interaction and multiscale mechanics
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• v.2 no.2
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• pp.129-151
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• 2009

This paper presents a meshfree procedure using a convex generalized meshfree (GMF) approximation for the large deformation analysis of particle-reinforced rubber compounds on microscopic level. The convex GMF approximation possesses the weak-Kronecker-delta property that guarantees the continuity of displacement across the material interface in the rubber compounds. The convex approximation also ensures the positive mass in the discrete system and is less sensitive to the meshfree nodal support size and integration order effects. In this study, the convex approximation is generated in the GMF method by choosing the positive and monotonic increasing basis function. In order to impose the periodic boundary condition in the unit cell method for the microscopic analysis, a singular kernel is introduced on the periodic boundary nodes in the construction of GMF approximation. The periodic boundary condition is solved by the transformation method in both explicit and implicit analyses. To simulate the interface de-bonding phenomena in the rubber compound, the cohesive interface element method is employed in corporation with meshfree method in this study. Several numerical examples are presented to demonstrate the effectiveness of the proposed numerical procedure in the large deformation analysis.

• Journal of Korean Association for Spatial Structures
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• v.16 no.1
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• pp.35-42
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• 2016

Until recently, almost all ETFE film structures that have been erected is the cushion type because there are problems at lower allowable strength under elastic range and viscosity behaviour such as creep and relaxation of ETFE films under long-term stresses. But the number of tension type structures is currently increasing. This paper proposes the stretch fabrication of ETFE film to verify the applicability of ETFE films to tensile membrane structures. First of all, to investigate the possibility of application on tensile membrane structures, the stretch fabrication test is carried out, and it is verified that it is possible to increase the yield strength of the film membrane structures. After simulating the experiment also carries out an analytical investigation, and the effectiveness of the elasto-plastic analysis considering the viscous behavior of the film is investigated. Finally, post-aging tension measurement is conducted at the experimental facilities, and the viscosity behavior resulting from relaxation is investigated with respect to tensile membrane structures.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1561-1584
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• 2011

This study aims at classifying and interpreting on the vegetation structure and analyzing the correlationship between communities and environmental conditions in Mt. Wolchulsan. We also predicted the succession possibility and the vertical distribution change of vegetations according to the global warming, through the pioneer species of a forest change and dominant species of canopy vegetations. We also analyzed the Raunkiaer's life-form. The communities in this ecotone are distributed vertically in the order of a Quercus acuta community, a Q. serrata-Q. variabilis community and a Q. serrata community. A Pinus densiflora community appears on the most of altitudes. The distribution of communities correlates highly with an altitude. The Q. serrata-Q. variabilis community will be succession to the Q. acuta community, and the Q. variabilis will be under natural selection gradually or remain locally. The Q. serrata community will possibly maintain as it is, and the P. densiflora community will be also under natural selection gradually. The valuable quantitative and numerical life-forms are confirmed and the layer structure of present vegetation will not be changed.

• Journal of Environmental Science International
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• v.22 no.8
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• pp.979-997
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• 2013

This study aims at classifying and interpreting on the vegetation structure, the correlation between a vegetation and an environment, a species diversity and a life-form of Evergreen Broad-Leaved Forest(EBLF) located in Gageo-do Island. It is also the objective that the estimation of vegetation change founded on the species composition and characteristics. The vegetation of EBLF was classified into three forests or four community units as Machilus thunbergii forest (Polystichum polyblepharon-M. thunbergii community and Phaenosperma globosum-M. thunbergii community), Ilex integra-Castanopsis sieboldii community, Quercus acuta community and Neolitsea sericea stand. The ordination analysis by DCA is analogous with the vegetation structure analysis. As a result of the correlation (Pearson's correlation coefficient) with environmental conditions, the Altitude has the significance with the distribution of communities. The total vegetation change by progress of succession will not be wandered away from the present vegetation structure practically, and the vegetation on the underlayers will be a little changed.

• Journal of Korean Association for Spatial Structures
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• v.14 no.3
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• pp.85-92
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• 2014

Most of the structural forms in which ETFE film is used are the cushion(pneumatic membrane structures) and tension type(tensile membrane structures), which have been generally accepted to be the most efficient forms. Tensile membrane structures are pulled outward from the exterior to introduce initial stress. And such structures offer the advantage of a natural shape formed by tensile stress and eliminate the need for blast air. Recently, the number of tension type structures is increasing. However, there are problems of creep and relaxation of ETFE films under long-term stresses. In this paper, the stretch fabrication method is proposed for stretching the film into the plastic region during initial tensioning as a way to increase its strength. And its effectiveness is confirmed by investigating experimental and analytical test using ETFE films.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.199-201
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• 2002

Cancer therapy using high-energy $^{12}$ C ions is successfully under way at HIMAC, Japan. An alternative beam to $^{12}$ C is $^{11}$ C ions. The merit of $^{11}$ C over $^{12}$ C is its capability for monitoring spatial distribution of the irradiated $^{11}$ C by observing the $\beta$$^{+}$ decay with a good position resolution. One of the several problems to be solved before its use for therapy is the amount of nuclear interaction that deteriorates the dose concentration owing to the Bragg curve. Utilizing the dedicated secondary beam course for R&D studies at HIMAC, we measured the total energy loss of $^{11}$ C ions in a scintillator block that simulates the soft tissue in human bodies. In addition to the total absorption $^{11}$ C peak, non-negligible bump-shaped contribution is observed in the energy spectrum. The origin of the bump contribution can be nuclear interaction of the incident $^{11}$ C ions with hydrogen and carbon atoms. Further studies to reduce the ambiguity in dose distribution are mentioned.

• Journal of Korea Port Economic Association
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• v.17 no.2
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• pp.29-59
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• 2001

This paper aims to describe port competition in East Asia and the Korean government's port strategy. In doing so, the paper provides an overview of global changes in international trade, the shipping industry and the port business. It also delineates the status of port competition in the region. Particular examples are taken from the competition among the ports of Hong Kong, Singapore, and Malaysia, as well as those of Pusan and Kwangyang, Kaohsiung, Kobe, and Shanghai and Yantian. The port competition in East Asia is reviewed and classified in two groups: north-tier competition among traditional major players, such as Kobe and Pusan, and dark horses such as Shanghai, Kwangyang and perhaps Yokohama; and south-tier competition among the three traditionally big players Kaohsiung, Hong Kong and Singapore, and the relative newcomers of Yantian in China, and Tanjung Pelepas In Malaysia. Due to the enlarging of ships and expansion of port activities, the boundary between the two tier frontiers breakdown, or they may even merge, into one grand frontier, in the foreseeable future. Although it appears that Asian ports are not being very aggressive in preparing for the future of mega-carrier in their plans, it is true that China, Korea and Taiwan are moving full steam ahead in comprehensively developing their container ports on a large scale. It therefore seems to be the perfect time for rival ports to explore a port alliance strategy to fight against the trend toward alliances between of many shipping lines.