• Journal of Navigation and Port Research
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• v.31 no.8
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• pp.725-731
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• 2007

This paper aims to analyze an action about a port choice of shipper between two ports. For this propose, this paper analyzed a port choice action for Kwangyang and Busan port using a fuzzy logic and neural network. Also, this paper compared classification performance of fuzzy-neural network to Logit model, and analyzed a port choice action into change Para-meta such as freight volumes and service standard.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.5
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• pp.248-254
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• 2001

The traction power demand highly varies with time and train positions and the traction load is a large-capacity current at single phase converted from 3-phase power system. Subsequently, each phase current converted from 3-phase power system cannot be maintained in balance any longer and thus the traction load can bring about imbalance in three-phase voltage. Therefore, the exact assessment of voltage unbalance must be carried out preferentially as well as load forecast at stages of designing and planning for electric railway system. The evaluation of unbalance voltage in areas, such as electric railway depots should be a prerequisite with more accuracy. The conventional researches on voltage unbalance have dealt with connection schemes of the transformers used in ac AT-fed electric railroads system and induced formulas to briefly evaluate voltage unbalance in the system(3). These formulas are still being used widely due to their easy applicabilities on voltage unbalance evaluation. Meanwhile, they don't take into account detailed characteristics of ac AT-fed electric railroads system, being founded on some assumptions. Accordingly. accuracy still remains in question. This paper proposes a new method to more effectively estimate voltage unbalance index. In this method, numerous diverted circuits in electric railway depots are categorized in three components and each component is defined as a two-port network model. The equivalent circuit for the entire power supply system is also described into a two-port network model by making parallel and/or series connections of these components. Efficiency and accuracy in voltage unbalance calculation as well can be promoted by simplifying the circuits into two-port network models.

• Journal of Korea Port Economic Association
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• v.25 no.2
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• pp.177-200
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• 2009

This study extracted the major attributes of the competitiveness of services provided by port logistics networks from previous research and interviews with experts and, based on the attributes, analyzed the effects of change in the competitiveness of the Incheon Port. According to the results, services provided by port logistics networks were divided into facility conveniences, access conveniences, and decision conveniences. In the results on the integrated value of the competitiveness of logistics network among ports, competitiveness was high in order of Busan Port>Qigndao Port>Tianjin Port>Dalian Port>Incheon Port. Particularly in the results of scenario analysis, with the elevation of one or two factors of logistics network service, the Incheon Port was even inferior to the Dalian Port, which had the lowest competitiveness among the ports compared. In the results of reversed fuzzy analysis, the Incheon Port could maintain equal competitiveness with the Dalian Port by raising the service level of the logistics network by 25% for facility conveniences, by 8% for access conveniences, and by 1% for decision conveniences.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.2
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• pp.144-150
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• 1989

The competitive power extraction problem in a linear n-port network consisting of resistances and independent sources with the same frequency is solved. For solving the problem, the definition of the two-port image impedances is extended to the n-port image impedances. In a competitive power extraction from an n-port network, the load resistances eventually approach the image resistances been found to be between the reciprocal of the short circuit conductance and the open circuit resistance.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.1
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• pp.77-84
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• 1998

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• Journal of Navigation and Port Research
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• v.36 no.7
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• pp.535-544
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• 2012

In order to improve the overall ASEAN maritime transport network, each port's efficiency is regarded as a crucial factor that should be calculated periodically. This study evaluated the relative efficiency of container port operations of 32 ports belonging to 9 ASEAN nations using Data Envelopment Analysis (DEA). It found that 2 out of 32 ports in 2010 were measured as efficient ports. This study yielded two major findings. Firstly, the ports assessed as inefficient need to benchmark similar ports in size and structure from the ports that are assessed as efficient to improve their efficiency. Secondly, these results could be used to determine potential candidates and country for an international port development co-operation programme with Korea to improve the performance of the entire ASEAN port network by developing the infrastructures of ill-equipped ports.

• Journal of Korea Port Economic Association
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• v.32 no.1
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• pp.97-122
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• 2016

Incheon port attained two million TEU of container throughput between 2013 and 2014 as a third port in domestic container throughput. It opened a new port in Song-do, Incheon in June 2015 to prepare for the continuing increase in container throughput.Therefore, it has provided the platform for being the major container port domestically and internationally. As the role of the new port increases, the role and direction of the Incheon port liner service network attracts attention. This study analyzes the centrality of the Incheon port liner service network by using SNA (Social Network Analysis), which was introduced in the maritime economics area recently, focusing on the Incheon port liner service network. We recognize the degree centrality, closeness centrality, and betweenness centrality of each port and its effect on the Incheon port liner service network. The study showed that for Incheon port, the centrality of the Busan port in Korea, and the Hong Kong port, is high outside the country. This helps us determine that the hub of the Incheon port is neither Shanghai nor Singapore, which ranks first and second, respectively, on container throughput. It is also helps us to know that eastern China's ports have not played a role of the hub of the Incheon port until now because of the relatively low centrality of eastern China's ports.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.589-593
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• 2013

An efficient measurement methodology is proposed to construct the scattering parameters of a multi-port device using a four-port vector network analyzer (VNA) without the external un-terminated ports. By using the four-port VNA, the reflected waves from the un-terminated ports could be minimized. The proposed method significantly enhances the accuracy of the S-parameters with less number of measurements compared to the results of classical renormalization technique which uses two-port VNA. The proposed method is validated from the measured data with the coupled 8-port micro-strip lines.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.159-167
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• 2000

During the operation of crane system in the container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances and weight change. In this paper, we present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control. Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.5
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• pp.541-548
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• 2013

This paper presents a vector network analysis system for 2-port scattering parameters of microwave devices using some basic microwave instruments/devices such as signal generators, vector voltmeter, directional couplers and frequency mixers. The analytical model and implementation method for scattering parameter measurements - which can replace the vector network analyzers - are presented. The performance of the implemented system is evaluated through 1- and 2-port scattering parameter measurements, respectively. The vector volt signals which determine the scattering parameters are detected in two distinct methods depending on the frequency band of interests; a direct-detection method with a single signal generator and vector voltmeter for relatively low band and a heterodyne method to frequency down-mix associated with an additional signal source as well as frequency mixers for high band are used, respectively. Using these two methods, scattering parameters of UHF and X bands are evaluated and their performances are verified through a comercial vector network analyzer.