• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.119-126
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• 2015

The information about noise parameters is essential in the design of low noise amplifier. In the past, the noise parameters were measured using an impedance tuner and noise figure analyzer. Recently, the authors proposed the method of measuring the noise parameters using the 8-port network without the aid of the mechanically driven impedance tuner. However, the 8-port method still requires the noise source and causes the complexity in the measurements. In this paper, a novel measurement method of the noise parameters without the noise source using 6-port network is proposed. Based on the proposed 6-port method, the noise parameters of 10 dB attenuator whose noise parameters can be theoretically determined were measured and the measured noise parameters are compared with those measured using the previous 8-port network method. As a result, the accuracy of the measured noise parameters using 6-port network is found to be comparable to the previous 8-port network method.

• Journal of Navigation and Port Research
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• v.28 no.7
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• pp.587-591
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• 2004

In order to measure the performance of resources in a port container terminal, we conducted a state transition network simulation to model various equipment processes. The processes that container cranes and transfer cranes perform are idle, wait, move, and work. Vehicles perform idle, wait, empty travel, and full travel. Because cranes, vehicles, and vessels are movable entities and all equipment is classified as either a customer or server, we separated the various stages of the process based upon the state transition network To validate the simulation results, a real system was used to illustrate the use of various measurements using the state transition network.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.93-99
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• 2023

This study aimed to determine relationships among risk factors influencing container port operation using Bayesian network. Risk factors identified from prior studies were classified into five groups: human error, machinery error, environmental risk, security risk, and natural disasters. P anel experts discussed identified risk factors to fulfil conditional probability tables of the interdependence model. The interdependence model was also validated by sensitivity analysis and provided an interrelation of factors influencing the direction of each other. Results of the interdependence model were partially in line with results from prior studies while practices in the global port industry confirmed interrelationships of risk factors. In addition, the relationship between top-ranked risk factors can provide a schematic drawing of the model. Accordingly, results of this study can expand the prior research in the Korean port industry, which may help port authorities improve risk management and reduce losses from the risk.

• Korea Trade Review
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• v.44 no.6
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• pp.267-283
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• 2019

This study analyzes how the port connectivity network has changed with the restructuring of the liner shipping alliance and explores the impact of these changes on network characteristics using social network analysis (SNA). While due to economies of scale, the scale of ports and liner shipping has expanded, the goal of shipping companies has changed to achieve cost-effectiveness due to the diseconomies of scale. Such changes in the environment have greatly affected ports according to the strategies of major liner alliances, and port centrality has shifted in response to restructuring in strategic alliances. This research confirmed that port centrality has continuously changed, and the reason for this phenomenon was analyzed through the derived main network centrality indices. This finding provides significant implications for port authorities and terminal operators to consider different perspectives when planning for sustainable growth and management.

• Journal of Navigation and Port Research
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• v.35 no.7
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• pp.605-611
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• 2011

In this paper, practical problems for current feeder service between Busan port and west coast of Japan were extracted through in depth interviews with Japanese feeder vessel companies, shippers, and port authority based upon which major criteria (elements) for improvement of the feeder network are structured in hierarchic order and weighed relative importance through AHP method. From the questionnaire answered by Korean and Japanese port users and experts the weights of criteria were calculated and the shipping service was ranked the first by both parties with 0.235 and 0.217, respectively. The port service and support system ranked the second and the third, whereas the port marketing was shown to be the lowest of all. Considering the overall weights, the increase in a port loading and unloading speed of port service was followed by provision of dedicated deck for feeder vessel of port facilities for Korean respondents. Therefore, speed up of the port operations and providing docks for feeder vessel are to be firstly provided for more efficient feeder operations, which would be the basis for the construction of optimal transportation network.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.117-133
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• 2021

This study aimed to identify its research trends using social network analysis(SNA). The results of the analysis showed that, for degree centrality, Busan Port(0.223) was the keyword that had the highest centrality, followed by DEA(0.060), AHP(0.056), and container terminal and port competitiveness(0.049). Busan Port(0.245) also had the highest betweenness centrality, followed by DEA(0.048), container terminal(0.044), AHP(0.039), and Busan New Port(0.032). The trend analysis inferred that efficiency analysis(DEA), strategy selection, and competition analysis(AHP) were the keywords with a high centrality for Busan Port to gain a competitive edge with global ports. However, research on the Fourth Industrial Revolution, which is emerging as a key issue, was insufficient. In the future, research using social data, such as mass media and social networks, is necessary.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.3
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• pp.99-106
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• 2002

This study presents an approach to model the Electric Railway System with the common grounding based on the 8-port network model and to analyse traction power feeding system focused on the amplification of harmonic current. The entire system can be easily modeled by the combination of 8-port representation of each component in parallel and/or series. Through the research, 8-port network model which can be effectively applied to harmonic analysis is derived.

• Journal of Korea Port Economic Association
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• v.27 no.4
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• pp.291-311
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• 2011

The modern ports have become multi-functionalized and network-centralized over time. Recently the development of industry in the land behind the port area has become very important for port itself. Furthermore, the port functions as a finance center and an integrated function of the main bank of the world. It will be necessary for Inchon port to pursue the policy for building itself as a hub center for logistics integration and building network in the region of Northern-East Asia and Seoul Capital City area in order for Inchon port to support and develop various industries through utilizing each aspect of the industrial complex in these areas. By doing this, it will act as a policy for strengthening competiveness for Inchon port. The sharp increase of cargo movement from rapidly developing Industries in China will become a good opportunity for strengthening the competitiveness of Inchon port. However, considering the characteristics of the ports competitiveness, this policy must quickly overcome the difficulties of Inchon port.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.85-96
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• 2017

In this paper, a 2~18 GHz wideband 6-port network is designed and fabricated to extend the measurement frequency bandwidth of noise parameter measurement method using 6-port network. In order to design a broadband 6-port network, a wilkinson power divider and a directional coupler with wideband characteristics are designed. The wilkinson power divider is designed as a three-section structure to achieve wideband characteristics. The direction coupler is designed as a three-section structure and slot-coupled structure using multi-layer substrate to obtain wideband characteristics. A wideband 6-port network is designed and fabricated combining the designed power divider and coupler. The measured results of the fabricated 6-port network for the 2~18 GHz band show characteristics applicable to the noise parameter measurement method.

• 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.