• Journal of Information Technology Applications and Management
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• v.26 no.1
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• pp.95-102
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• 2019

Public transportation systems play key roles in supporting dynamic activities and interaction between urban places. Especially, high efficient public transportation systems are required in order to support large traffic demands in urban areas. In this paper, we define a new metric, structural activation level (SAL), to replace the conventional transportation share ratio (TSR) measuring efficiency of public transportation systems. First of all, we access the Korea Transport Database (KTDB) and download origin-destination data by transport types to construct traffic networks with respect to transport types for each city. Then, we calculate the QAP (Quadratic Assignment Procedure) correlation between each traffic network and the total traffic network for each city to investigate SAL by comparing cities one another. The results of our investigation reveal inconsistency between TSR and SAL. In Daegu, TSR of public transportation systems is relatively low while SAL is high. In Deajeon, however, SAL is low while TSR is high. Therefore, we suggest to take into consideration SAL as well as TSR in order to investigate the degree of activation of public transportation.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.775-789
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• 2011

Centering on KTX stations, Korea is implementing specialized development of metropolitan business zones nationwide and is in the process of building the transfer link system of transportation in order to actualize intermodalism nationwide. Daejeon station, hub of high-speed railway requires the effective transportation transfer system considering Daejeon station area reorganization plan and opening of second phase high-speed railway. Based on the analysis of the possibility and validity of building a transit center under the Transportation System Efficiency Act, it is necessary to make a mutual benefit in a regional development by installing the resonable transfer system between railway and other transportation services. Through analysis of current situations and technical, economic and environmental feasibility evaluation, design plan of effective transportation transfer system in Daejeon station is proposed.

• Proceedings of the Korea Port Economic Association Conference
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• 2007.10a
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• pp.161-173
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• 2007

This paper considers the problem of determining the cargo flow and the transportation mode in each trade route while satisfying the demand. Especially, the problem incorporates short sea shipping in Korea, which is becoming more important in order to improve efficiency of Logistics. The objective is to minimize the sum of shipping and inland transportation costs. To solve optimally the problem, this paper employs a linear programming model, which is an operations research technique for optimization. The problem is formulated by extending the well-known network design problem by considering capacity at seaport and limitation of total number of vehicles. The model is solved using CPLEX, a commercial linear program software. The test results using a real cargo flow data in Korea show that the model represents closely the real situation.

• Journal of applied mathematics & informatics
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• v.24 no.1_2
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• pp.449-460
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• 2007

Several fuzzy approaches can be considered for solving multi-objective transportation problem. This paper presents a fuzzy goal programming approach to determine an optimal compromise solution for the multiobjective transportation problem. We assume that each objective function has a fuzzy goal. Also we assign a special type of nonlinear (hyperbolic) membership function to each objective function to describe each fuzzy goal. The approach focuses on minimizing the negative deviation variables from 1 to obtain a compromise solution of the multiobjective transportation problem. We show that the proposed method and the fuzzy programming method are equivalent. In addition, the proposed approach can be applied to solve other multiobjective mathematical programming problems. A numerical example is given to illustrate the efficiency of the proposed approach.

• Journal of Korea Port Economic Association
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• v.22 no.2
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• pp.19-33
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• 2006

The efficiency and effectiveness of freight transportation within and across Northeast Asia playa key role to achieve competitive advantages against other competing hubs in this area. However, the majority of local freight has been carried by ground transportation and the share of costal shipping has been decreasing for its transportational complexity and poor cargo works. In this paper, we discuss the prerequisites of efficient cargo linkage system from the perspectives of road, rail, ocean, and the service providers. Specifically, we identify that the balanced capacity of road/rail transportation system with costal freight system is a crucial component for facilitating coastal shipping. Other requirements such as the efficient on-dock container yard (ODCY), dedicated ports and ships, and the service provider of door-to-door transportation for short sea shipping are highlighted in order to secure the serviceability and availability of streamlined costal shipping. Further, we elaborate these requirements to facilitate costal cargo shipping in Korea.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.4
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• pp.56-62
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• 2003

Recently, in order to stay at predominance in the global infinity competition, most of companies have been reducing the cost in many fields of industry First of all, the reduction of the logistics cost have been recognized greatly as the company value rises. But, the current situation of domestic logistics cost is very weak compared with Japan, U.S.A., etc. A rate of logistics cost out of GDP is still high compared with the competitors. The reduction of the transportation cost from overall logistics cost is most urgent subject. One of the methods to make a domestic transportation system efficient is the consolidation. In this paper. we try to compare the consolidated transportation model for a cost reduction with individual case. We also analyze the efficiency of consolidated transportation using simulation program with Arena of System Modeling Company.

• IE interfaces
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• v.20 no.4
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• pp.525-538
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• 2007

The importance of efficient container transportation becomes more significant each year due to the constant growth of the global marketplace, and studies focusing on shipping efficiency are becoming increasingly important. In this paper, we propose an approach for vehicle scheduling that decreases the number of vehicles required for freight commerce by analyzing and scheduling optimal routes. Container transportation can be classified into round and single-trip transportation, and each vehicle can be linked in a specific order based on the vehicle state after completing an order. We develop a mathematical model to determine the required number of vehicles with optimal routing, and a heuristic algorithm to perform vehicle scheduling for many orders in a significantly shorter duration. Finally, we tested some numerical examples and compared the developed model and the heuristic algorithm. We also developed a decision support system that can schedule vehicles based on the heuristic algorithm.

• International Journal of Railway
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• v.1 no.2
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• pp.45-58
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• 2008

The concept of lean production originated and was applied mainly to manufacture industries Even proven successful with such companies as Toyota, lean production has to be combined railway transportation production in order to bring its function into full play. The paper analyzes for applicability of lean production in railway transportation production organization, puts forward implementation methods such as transportation resource integration, station-zone organization, dispatch command optimization, railway performance evaluation index system, etc., and makes an exemplification study of lean production of Urumqi Railway Bureau in China, which testifies the applicability and efficiency of railway lean production.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.307-313
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• 2002

Due to the fact that high speed railroad will be opened to traffic and TSR and TCR will be connected to Korean railroad network in near future, the efficient operation methods of Railroad freight transportation have been embossed as a matter of concern. But, it is true that the present level of our railway infrastructures and operation systems are still low. This study examines the freight transportation system and introduces new logistic service systems including network strategies and terminals which are haying developed overseas to increase the efficiency of existing railroad transportation system. In case of giving careful consideration to the new methods, it is expected that the high developed freight transportation systems will be applicable to our country.

• Journal of the Korean Chemical Society
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• v.59 no.2
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• pp.142-147
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• 2015

Two new chitosan derivatives, polyamine grafted chitosan copolymers have been synthesized for corrosion protection of carbon steel in acidic medium. First, methyl acrylate graft chitosan copolymer (CS-MAA) was prepared by the reaction of chitosan (CS) and methyl acrylate (MAA) via the Michael addition reaction. Then, CS-MAA was reacted with ethylene diamine (EN) and triethylene tetramine (TN) respectively to synthesize ethylene diamine grafted chitosan copolymer (CS-MAA-EN) and triethylene tetramine grafted chitosan copolymer (CS-MAA-TN), and the structures were characterized by Fourier-transform infrared spectroscopy (FT-IR). At last, the corrosion inhibition activities on Q235 carbon steel were investigated by using gravimetric measurements, metallographic microscope, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The compounds CS-MAA-EN and CS-MAA-TN show an appreciable corrosion inhibition property against corrosion of Q235 carbon steel in 5% HCl solution at $25^{\circ}C$. It has been observed that CS-MAA-EN shows greater corrosion inhibition efficiency than CS-MAA-TN. The inhibition efficiency of CS-MAA-EN was close to 90% when the mass fraction concentration was 0.2%~0.3%; the inhibition efficiency of CS-MAA-TN was close to 85% when the mass fraction concentration was 0.02%. The present work provided very promising results in the preparation of green corrosion inhibitors.