• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.3
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• pp.216-224
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• 2011

In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995) and Larson and Kraus (2002). Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF) basin and the Hazaki Oceanographical Research Station (HORS). Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.95-104
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• 1998

Water pollution in a semi-enclosed sea area such as a bay due to stagnancy of water has been a serious water environmental problem. Recently, some kinds of new methods to activate the tidal exchange between an inner bay and an outer sea area by control of a tidal residual current have been proposed. However, these methods have several problems, that is, I). deterioration in a natural view due to building of huge structures, II). increase of risk of navigation in case of a submerged structure, III). limition of sea area where a tidal current can be controlled and IV). difficulty in removing those structures in case of occurrence of an unexpected impact on water environment. In this paper, a new method is proposed, which can solve all the above problems, to purify water quality in a semi-enclosed bay by creation and control of a pattern of a tidal residual current. The tidal residual current is controlled by unsymmetric structures, which change the properties of resistance according to the direction of flow, arranged on the sea bottom. In this study, several numerical and hydraulic experiments of tidal current and particle-tracking for various arrangements of bottom roughness in a semi-enclosed model bay were carried out. As a result of experiments, it becomes clear that it is possible to generate a new tidal residual current and to activate a tidal exchange by only operation of bottom roughness arrangement.

• Journal of the Korean association of regional geographers
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• v.18 no.1
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• pp.55-70
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• 2012

Busan port has played a part as the main trade gateway in Korea for several decades. However, due to the rapid integration of China into the global economy and the grand changes in global trade structures, the trade gateway system in Korea and the status of Busan port have been transformed. Busan port's role as a trade gateway toward Japan and U.S. has increased during last two decades but, in cases of China, its importance has relatively decreased. Moreover, Busan port's competitiveness has been undermined in the most part of commodity trade. These phenomena reflect the high competition among trade ports which tend to increase the effectiveness of supply chains. Based on the geographical research tradition which has understood a port as a nexus between hinterland and foreland, this study focuses the changes in characteristics of trade freights and the status as a gateway of Busan port. This approach will contribute to the understandings of dynamics in the comtemporary international logistics.

• Journal of Navigation and Port Research
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• v.40 no.3
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• pp.139-146
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• 2016

Due to the continuous increasement of the container cargoes, each container port market has been growing as well. Moreover, the competition among container terminal operators located in the same port is also growing in order to attract more container cargoes. This paper looked into the market structures, market conducts and market performances of container ports in Busan and Shanghai. The index which has been most widely used to measure market structure, the Hirschman-Herfindahl Index (HHI), is computed by squaring each supplier's market share, then adding the squared shares. This paper estimated the market performance as profitability (PCM, ROA), growth (total TEU, rate of the increasement of TEU) and examined the effects of the HHI on the profitability and growth in a container terminal operators in Korea and China. The major findings of this study is that the market structure has effects on market performance in Busan port (total TEU) and Shanghai port (PCM, ROA and total TEU). As a result of analysing this study, market structure has an effect on market performance in Busan and Shanghai port, but the power of influence can be changed by market concentration index and various market conduct of companies.

• Journal of Information Management
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• v.30 no.1
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• pp.11-28
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• 1999

STN(The Scientific & Technical Information Network) is a fee-based, comprehensive, online search service that provides. accurate, up-to-date information from over 200 scientific, technical, business, and patent databases. STN Easy(http: //stneasy.cas.org) provides point-and-click access to 59 selected key STN databases on the web, and it gives drawings and 3-dimensional chemical structures as well as citation-abstract informations. And information searchers are now able to access full-text documents from key scientific publishers and patent offices through STN Easy via the ChemPort(http://www.chemport.org) connection.

• Steel and Composite Structures
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• v.41 no.6
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• pp.887-898
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• 2021

This paper presents a simplified model to capture the nonlinear behavior of steel frames depending on the spread of plasticity method. New interaction formulae were derived to evaluate the plastic strength for I-shaped steel sections under uniaxial bending moment and axial compression load. Also, new empirical formulae were derived to evaluate the tangent stiffness modulus of steel I-shaped cross-sections considering the effect of the residual stresses suggested by the specifications in European Convention for Construction Steelworks (ECCS). The secant stiffness which depends on the tangent modulus is used to evaluate the internal forces. Based on stiffness matrix method, a finite element analysis program was developed for the nonlinear analysis of space steel frames using the derived formulae. Comparison between the proposed model results with those given by the fiber model shows very good agreement. Numerical examples were introduced to verify, check the accuracy, and evaluate the efficiency of the proposed model. The analysis results show that the new proposed model is accurate and able to minimize the solution time.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.433-438
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• 2005

This study was carried out to analyze the effect of the variation of a wind speed on the stability of a container crane. The wind load according to 'The Requirement of Port Facilities and Equipments / Specification for the design of crane structures (KS A 1627)' and 'Load Criteria of Structures' enacted by the ministry of construction & transportation was evaluated. And the uplift forces of a container crane under this wind load were calculated by analyzing reaction forces at each supporting point and compared with each other. The analytic model was a container crane with uplift capacity of 50ton which was widely used in port.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.9
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• pp.862-876
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• 1991

In this theses, the procedure for finding the equivalent immittance of an n-line coupled structures is presented in terms of the normal mode parameters of the n-line coupled system. The above generalized equations can be applied to the various Coupled structures including directional couplers, DC blocks, bandpass/band elimination filters, and various other uniformly coupled filters. The design equations are based on a simplified TEM(Quasi TEM) mode. The obtained results and the definition of the scattering parameters for a general coupled line four port with arbitrary terminations are used to present the procedure to determine the optimum physical dimensions matching the given load impedances connected to input, output port. Multiple coupled rnicrostrip two-port with three lines circuit designed shows little discrepancy between the conventional method and this one. Four port with five lines were fabricated on teflon substrate($e$r=2.55) with its thickness h=l.588mm designed at the center frequency, 4 GHz. Their measured results are fairly close to the ones by computation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.118-125
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• 2014

As the earth's current global warming has caused elevation of sea water temperature, size of storms is foreseen to increase and consequently large damages on port facilities are to be expected. In addition, due to the improved processing efficiency of port cargo volume and increasing necessity for construction of eco-friendly port, demands for various forms of port facilities are anticipated. In this study, two kinds of nondestructive evaluation (NDE) techniques (rebound hardness and ultrasonic pulse velocity methods) are investigated for the effective maintenance of smart green harbor system. A new methodology to estimate the underwater concrete strengths is proposed and its feasibility is verified throughout a series of experimental works.

• Journal of Navigation and Port Research
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• v.33 no.10
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• pp.743-756
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• 2009

This paper tries to analyze how the governance institutions of the Port Authority of New York and New Jersey overcome agent problems in public agencies based on the Principal-Agent Theory, and find the implications that will be helpful to the governance of port authorities in Korea. The Port Authority's governance is characterized by decentralization of personnel rights, open meetings policy, freedom of information policy, public hearings, and fiscally self-supporting system. Those characteristics are helpful in overcoming the agent problems of public agency, such as adverse selection, moral hazard, and complicated external structure, through reinforcing of monitoring agent by principal, easing of information asymmetry between principal and agent, and clarification of organizational ownership structure. Those characteristics may give many implications for the design of governance structures of port authorities in Korea.