• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.87-96
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• 2018

A trajectory control system plays an important role in controlling motions of marine vehicle when a series of way points or a path is given. In this paper, a sliding mode control (SMC)-based trajectory tracking controller for marine vehicles is presented. A small-sized unmanned ship is considered as a control object. Both speed and heading angle of a ship should be controlled for tracking control. The common point of related researches was to separate ship's speed and heading angle in control methods. In this research, a new control law from a general sliding mode theory that can be applied to MIMO (multi input multi output) system is derived and both speed and heading angle of a ship can be controlled simultaneously. The propulsion force and rudder force are also applied in modeling stage to achieve accurate simulation. Disturbance induced by wind is also tackled in the dynamics considering robustness of the proposed control scheme. In the simulation, we employed a way-point method to generate ship's trajectory and applied the proposed control scheme to ship's trajectory tracking control. Our results confirmed that the tracking error was converged to zero, thus demonstrating the effectiveness of the proposed method.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.555-561
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• 2002

The shipboard working environment of coastal patrol ship is very inferior to the ground working environment and it causes the avoidance of shipboard working and the aging of crew. Especially the air pollution and electromagnetic wave in ships causes an occupational disease. Hence of reduce the shipboard working fatigue is necessary by the security of the comfortable shipboard working environment. In this paper, firstly we evaluate the shipboard working environment by using the measurement results of the shipboard air pollution and electromagnetic wave in the sea. And we propose the measures to reduce the shipboard working fatigue which is based on the evaluation results of the shipboard working environment.

• Journal of Navigation and Port Research
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• v.30 no.5 s.111
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• pp.321-329
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• 2006

The ultimate target cf this study is to develop ship's Digital Compass that can substitute for conventional ship's Magnetic Compass. At first, a new Digital Compass system consisting of three-axis Flux-gate sensors and small sized step motor was developed Then, new deviation adjustment theory incorporating with Kalman filter method was proposed through which automatic deviation analysis and correction are obtainable without ship's swinging procedures. The effectiveness of developed Digital Compass and proposed deviation adjustment theory are verified throughout the performance evaluation tests on the training ship 'SAE-NU-RI'.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.77-85
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• 2006

The last target of this study is to develop ship's Digital Compass that can be substitute with conventional ship's Magnetic Compass. At first, new Digital Compass system was developed with three-axis high accuracy Flux-gate sensors and small sized step motor. Then after, new deviation correction theory without ship's swinging procedures was proposed to provide automatic deviation analysis, correction and renewal. Throughout the performance evaluation tests on the training ship 'SAE-NU-RI', the effectiveness of developed Digital Compass and proposed deviation correction theory are verified.

• Journal of Korea Port Economic Association
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• v.22 no.3
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• pp.161-188
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• 2006

The purpose of this study is to analyze traffic volume between the Korean container ports located at the west coast and northern Chinese ports and then the distribution trend of container between Korea and China. The findings of the study are as follows. First, Container traffic between western Korean ports and northern Chinese ports has been increasing due to an increasing trade volume between both countries and geographical accessibility. Second, Seoul and neighboring area tend to use the trade route between the western ports and northern Chinese because of lower logistics costs and time-saved advantage compared to another ports. Third, the growth of the western ports did depend mainly on the northern China oriented growth. Such a fact could leads to the overlapping investment in port development in Korea and another intense competition among national ports to attract cargoes and liners. Therefore, port development policy considering the characteristics and function of national ports have to be established. and also alternatives and strategies for improving the competitive edge of small and medium sized shipping lines against the opening of shipping market have to be worked out.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.1
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• pp.27-38
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• 2023

How the port, shipping, shipbuilding, and vender industries in Korea can have a seamless value chain through their digitally smooth cooperation by applying the latest information and communications technology through the "4th industrial revolution" was examined. Also considered was the proposition that the value chain should be a smart, seamless value chain among industries with successful hyperconnection. Their cooperative relationships were defined, and the crucial elements for the sustainable development of these industries were considered. As a result, the direction for achieving environmental, social, and governance management by realizing decarbonization through today's digitalization could be studied. In particular, the importance of digitization as a way to respond to the future market from the perspective of small and medium-sized enterprises and the role of digitization realized by small and medium-sized equipment companies in the overall industry were examined. The results simultaneously show the state of linkage between industries and the reason why the value chain must maintain a smooth relationship. In addition, using the lessons learned from recent failure cases from the Korean shipbuilding industry as a cornerstone, the direction for creating a strategic pathway for intelligent connection was investigated.

• Journal of Internet Computing and Services
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• v.4 no.6
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• pp.69-73
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• 2003

ATM and Ethernet are desirable transport mechanisms for the realization MAN(Metropolitan Area Networks). A relatively small sized switching system for MAN based on ATM is proposed and its performance is evaluated in this paper. For the performance evaluation, traffics should be firstly modeled because they are highly bursty. By varing the ratio of VBR traffics, detrimental effect of VBR traffics may be observed. Traffic load at each input port is also varied, From the results of simulation, operation conditions of the system to meet required QoS are obtained.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.18-25
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• 1994

If a 4-port network is terminated by arbitrary impedances, there are great advantageges in composing systems with it. The distributed 3-dB $O^{\circ}$/180$^{\circ}$ hybrid with the impedances asymmetrically terminated is presented. In the band of UHF and VHF. on the basis of it , the new design method of small sized- hybrid using both lumped and distributed elements is also presented and analyzed At the center frequency of 900MHz. 3-dB $O^{\circ}$/180$^{\circ}$hybrid on the RT/Duroid substrate of ${\varepsilon}_{r}$=2.2, h=0.76mm is design and tested. Agreements are obtained between measured and theoretical results and at the same time the occupied area of it is reduced more than 70% compared with only distributed-type circuits.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.74-75
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• 2017

The operations of the warehouses are labor intensive. Automation of the warehouse is made by efforts to shorten the work time and reduce the cost according to the change of the production form of the company and the buyer's demand. Storage warehouses vary in size and shape, and equipment and facilities used in storage warehouses vary according to purpose and use. In order to automate storage, it is necessary to introduce an operating system, which varies depending on the type of equipment and operation policy. In this paper, we review the requirements for the automation of small and medium-sized storage warehouses, and classify the equipment selection and operating system options into effective scenarios to introduce an effective automation system. Therefore, simulation is performed for each scenario, and the effect of automation is examined, and the effect of automation is verified through economic analysis through cost for automation introduction.

• Animal Systematics, Evolution and Diversity
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• v.33 no.1
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• pp.8-16
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• 2017

We firstly described a box jellyfish, Carybdea brevipedalia collected from the southern coasts of Korea. It is morphologically characterized by gastric phacellae, a special digestive system of cubozoan jellyfish, and velarium, the thin muscle flap forming the opening of the subumbrellar cavity. The phacellae are linear-shaped, comprising numerous cirri branched from multiple roots. Each root also has multiple numbers of cirrus bundles. Basis of velarial cannels parts into two branches in each octant of velarium. Its geographic distributions were limited to Jeju-do and the middle-southern coasts where the organisms are seriously hazardous to bathers in summer. Numerous individuals and/or large-sized populations were observed specifically from beaches at Jeju-do, Namhae-do and a small fishing port of Namildae, while only a small amount of the individuals was observed in Gamak Bay, Jaran-Goseung Bay, and Geoje-do. We confirmed molecular identity of the Korean C. brevipedalia with comparison of nuclear ribosomal DNA sequences. Until now, Carybdea brevipedalia is the only cubozoan species reported to be distributed in Korean waters.