• Journal of Korean Society of Transportation
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• v.6 no.2
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• pp.7-20
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• 1988

Recent developments in combining transportation planning models and input-output approaches, together with inclusion of intensity of land uses, have made it possible to construct realistic comprehensive urban and regional activity models. These modes form the basis for a rigorous approach to studying the interactions among urban activities. However, efficient computational solution methods for implementing such comprehensive models are still not available. In this paper an efficient solution method for the urban activity model is developed by combining Evans' partial linearization technique with Powell's hybrid method. The solution algorithm is applied to a small but realistic urban area with a detailed transportation network.

• Journal of Korean Institute of Industrial Engineers
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• v.16 no.1
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• pp.27-36
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• 1990

This study deals with the dynamic transportation-inventory model for a single product from which the optimal procurement quantities and the transportation modes are determined simultaneously over a finite planning horizon. Moreover, it covers the situation where quantity discounts are applied to the transportation cost as well as the purchase cost and disposals of the excess are possible at the end of each period. For a relevant mathematical model formulated, the theorems and properties of an optimal solution are discussed to present the efficient algorithm. A numerical example is solved to illustrate the algorithm developed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6D
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• pp.801-807
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• 2008

This study attempts to evaluate and compare the land consumption efficiencies of various urban transport modes, utilizing the time-area method. With the careful considerations of travel conditions and modal characteristics, equations for the computation of time-area for various different modes are derived. With the appropriate assumed values of parameters, time-area consumptions per person per km for each mode both for peak and off-peak situations are computed and evaluated. The relationships between the time-area consumed and operating speed for each mode are graphically demonstrated and discussed. An example of the time-area consumed for a hypothetical commuter round-trip using various modes are also presented in order to clearly show the consumption of parking requirements by specific modes. It shows that regardless of facilities used, auto users are by far the worst in terms of area efficiency and that transit, especially rail rapid transit, is a superior mode. Pedestrian and bicycle, though consuming more than expected, also demonstrate the advantage in case of a short-distance trip in terms of area efficiency compared with the bus transit modes.

• Journal of Ocean Engineering and Technology
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• v.13 no.3B
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• pp.116-126
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• 1999

The purpose of this study is to analyze the economic aspect of sea transportation system between Inchon and Youngjong island in which Inchon international airport is being constructed. Total demand of sea transportation arising from in the airport and Yongyu Muwi leisure complex was estimated. To select optimum transportation route, environmental conditions in and around Inchon harbour and Youngjong island including the change of water depth by tide current, fog, rain, wind adn typhoon, ets., were investigated. The preliminary consideration on ships (size, velocity, transport capacity, price), routes, operational modes, terminals and berthing facilities were carried out. The transportation cost per passenger by sea transportation system was estimated to compare with that of land transportation system. It was found that sea transportation system proposed is competitive to the transportation system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1D
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• pp.23-31
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• 2012

Busan Metropolitan City government has been implementing the local Bus Quasi-Public Operating policy since 2007. As a result of the policy, financial burden to cover financial deficit has become a big social issue. For successful settlement of the policy, the government should be able to gradually cut off the financial support for the deficit by continuously increasing the bus demand, which can be accomplished by providing more convenient bus services. The weather conditions that affect the public transportation demand include rain, fog and snow. They affect the mode choice for public transportation use, which in turn results in decrease in bus demand. In short, the adverse weather conditions result in significant profit loss of bus transportation, and consequently it financially burdens the City of Busan. In this research, the pattern of travelers' use of transportation modes given various weather conditions was analyzed. In addition, the reasons why people transfer from one to other transportation modes were analyzed by conducting a field survey, and policy implications on desirable public transportation facilities and transfer system were discussed.

• Journal of Korea Port Economic Association
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• v.22 no.1
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• pp.175-198
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• 2006

This paper presents a network capacity model that can be used as an analytical tool for strategic planning and resource allocation for multimodal transportation systems. In the context of freight transportation, the multimodal network capacity problem (MNCP) is formulated as a mathematical model of nonlinear bi-level optimization problem. Given network configuration and freight demand for multiple origin-destination pairs, the MNCP model is designed to determine the maximum flow that the network can accommodate. To solve the MNCP, a heuristic solution algorithm is developed on the basis of a linear approximation method. A hypothetical exercise shows that the MNCP model and solution algorithm can be successfully implemented and applied to not only estimate the capacity of multimodal network, but also to identify the capacity gaps over all individual facilities in the network, including intermodal facilities. Transportation agencies and planners would benefit from the MNCP model in identifying investment priorities and thus developing sustainable transportation systems in a manner that considers all feasible modes as well as low-cost capacity improvements.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.127-134
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• 2006

In Korea, the number of recreational vehicle (RV) has been increased dramatically recent year. Now there are emission regulations for RV which include pollutants such as CO, HC, NOx, PM. However considering the trend of preferring RV, there needs more strict strategies to control emissions from this type of vehicle. For that reason, we studied emission characteristics of RV and provided basic emission data to evaluate the contribution of RV to the total air pollutant emissions and to establish RV emission management plan. A total of 21 RV were tested on the chassis dynamometer system ranging from small to large engine displacement by vehicle speed, fuel types, regulations and fuel efficiency in order to investigate the characteristics of CO, HC, NOx and PM. For the test modes, 10 different driving speed modes and CVS-75 mode were used. On the basis of this study, RV pollutants emission factors and management strategies will be proposed.

• Smart Structures and Systems
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• v.10 no.4_5
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• pp.353-373
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• 2012

The instrumented Canton Tower is a 610 m high-rise structure, which has been considered as a benchmark problem for structural health monitoring (SHM) research. In this paper, an improved automatic modal identification method is presented based on a natural excitation technique in conjunction with the eigensystem realization algorithm (NExT/ERA). In the proposed modal identification method, damping ratio, consistent mode indicator from observability matrices (CMI_O) and modal amplitude coherence (MAC) are used as criteria to distinguish the physically true modes from spurious modes. Enhanced frequency domain decomposition (EFDD), the data-driven stochastic subspace identification method (SSI-DATA) and the proposed method are respectively applied to extract the modal parameters of the Canton Tower under different environmental conditions. Results of modal parameter identification based on output-only measurements are presented and discussed. User-selected parameters used in those methods are suggested and discussed. Furthermore, the effect of environmental conditions on the dynamic characteristics of Canton tower is investigated.

• Smart Structures and Systems
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• v.23 no.6
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• pp.669-682
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• 2019

Vibration mitigation of cables or hangers is one of the crucial problems for cable supported bridges. Previous research focused on the behaviors of cable with dampers or crossties, which could help engineering community apply these mitigation devices more efficiently. However, less studies are available for hybrid applied cross-ties and dampers, especially lack of both analytical and experimental verifications. This paper studied damping and frequency of two parallel identical cables with a connection cross-tie and an attached damper. The characteristic equation of system was derived based on transfer matrix method. The complex characteristic equation was numerically solved to find the solutions. Effects of non-dimensional spring stiffness and location on the maximum cable damping, the corresponding optimum damper constant and the corresponding frequency of lower vibration mode were further addressed. System with twin small-scale cables with a cross-link and a viscous damper were tested. The damping and frequency from the test were very close to the analytical ones. The two branches of solutions: in-phase modes and the out-of-phase modes, were identified; and the two branches of solutions were different for damping and frequency behaviors.

• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.261-266
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• 1999