• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.135-143
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• 2004

In the land section of marine bridge construction site, to confirm the end bearing of large diameter drilled shaft constructed in the fault zone which was discovered unexpectedly, the hi-directional end loading tests were performed. The objectives of this study are to confirm the end bearing of the pile constructed in fault zone and the increasing effect of end bearing after grouting the base ground beneath the pile toe. After grouting the pile base ground, the settlement of pile base decreased considerably and the pile base resistance increased more than twice.

• Journal of the Korean Society of Safety
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• v.29 no.6
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• pp.87-93
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• 2014

In this study, the reinforced concrete rahmen bridge damaged by the chloride attack was investigated. According to the investigation, the degraded concretes on cantilever kerb and end part were intensively observed. Thus, the chloride content test and half-cell method were performed to evaluate the degraded parts. As a result, the contents of chloride on degraded parts were C and D grade. On the other hand, the half-cell potential values of rebar in degraded concrete were measured with the minor corrosion. This rebar corrosion is expected to progressing. Chloride content D grade is due to expansion pressure by corrosion of rebar and freeze-thaw by permeate water, could see progresses rapidly degradation. In order to prevent chloride attack to concrete deck caused by deicing salts, corresponding to the chloride critical concentration must maintain grade b or at least grade c. Chloride condition evaluation standard apply to evaluation of marine structure chloride attack with chloride attack by deicing salts.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.296-298
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• 2007

국내 해상교량에 건설에 있어서 일반적인 절계 기준에 대한 제도가 정착되지 않아 항만을 이용하는 관계자와 해상교량을 건설하는 주체와의 갈등이 지속적으로 반복되고 있는 실정이다. 이는 항만 이용자 측면에서는 항만의 경쟁력 확보를 위해 선박 통항에 지장을 초래할 수 있는 해상교량에 대해 보다 엄격한 설계 조건을 요구할 수밖에 없고, 반면 해상교량 건설자 입장에서는 교량 건설에 따른 경제성을 고려해야 하므로 일정 규모 이상의 교량건설이 현실적으로 불가능하기 때문이다. 본 연구에서는 국내외 해상교량 관련 기준 및 절차 등에 대한 분석을 기초로 설계 기준 초안을 작성하여 해상교량 건설 관계자(항만협회, 건설교통부, 건설회사, 지차체 등)와 항만 이용자(도선사협회, 선박회사 등), 그리고 해양계열 대학 전문가의 의견을 충분히 수립하여 국내 실정에 적합한 해상교량 설계 기준안을 제시하고자 한다.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.799-806
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• 2004

Recently, as the forerunner in establishing the Northeast Asia's logistics base, a lot of marine engineering works such as new ports and container terminals, extension of old ports, new bridges, land reclamation etc. have been progressed. Parallel to it, there is also an increasing demand for improving the safety of construction. In this situation, high resolution seismic reflection profiling can be well used, attempting to classify rocks and sediments under water, if possible, to delineate the distribution of grain sizes in sediments not only for calculating the cost of removing sediments from harbour's channels, but also for estimating the bearing capacities for bridge or port construction. However, the results from the corresponding reflection survey that has been in operation in our country can not be effectively used for engineering purposes mostly due to the insufficient resolution. Thus. in this paper, two innovative strategies are introduced to enhance resolution. The one deals with a newly designed exploration barge that will help reduce several kinds of noises encountered electrically or operationally. The other is associated with an establishment of optimum measuring system comprising e.g. a specially devised hydrophone with a combination of 7 piezoelectric elements. Field experiments performed at Busan harbour are illustrated. The quality of acquired data was thereby fundamentally improved in comparison with that obtained at the same time in a conventional way.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.83-90
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• 2016

This study was performed to evaluate the effective analysis of flexural performance for polypropylene fiber (PF) reinforced EVA concrete that can be used in marine bridge, tunnel and agricultural structures under flexural load. The control design was applied in ready mixed concrete using 10 % fly ash of total binder weight used in batch plant. On the basis of the control mix design, there was designed mix types that contained PF ranged from 0 % to 0.5 % by volume ratio into two mix types of using 0 % and 5.0 % EVA contents of total binder weight. Before evaluating the flexural performance, we tested compressive strength and flexural strength to evaluate whether polypropylene fiber reinforced concrete could be used or not in site. The method of flexural performance evaluation was applied by ASTM C 1609. These results showed the maximum compressive strength and flexural strength was measured at each E5P1 and E5P2. Concrete reinforced with PF exhibited deflection-softening behavior. In the concrete reinforced with 0.4 % PF contents and containing 5.0 % EVA, the flexural performance was the best.

• Journal of the Korean Institute of Navigation
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• v.20 no.1
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• pp.1-10
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• 1996

The assesment of the safety of ship's transit in a curved narrow channel consists of the maneuvering safety determined by the chance of running aground, the maneuvering difficulty determined by ship's workload, and shiphandler's subjective evaluation. In this study, to examine the correlation between shiphandler's subjective evaluation and the maneuvering safety, the real-time and full-mission shiphandling simulator in the Korea Marine Training & Research Institute(KMTRI) was utilized. On the conning bridge of the shiphandling simulator, 50 experienced masters have conducted the modeled vessel of 60, 000 deadweight tonnage along the designed channel under 3 different environmental conditions. It was possible to assess and analyze theoretically the correlation between the shiphandler's subjective evaluation and maneuvering difficulty under each environmental condition by quantifying the data obtained from the tests. The results are as follows: $\circled1$ As the degree of maneuvering difficulty increases, the shiphandler's subjective evaluation increases in the designed channel under the designed environmental condition. $\circled2$ In the straight area, not the bend of the designed channel, maneuvering difficulty increases sharply under the environmental condition of current and wind coming from the stern.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.245-246
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• 2014

This paper suggests the navigation information display system which is based on augmented reality technology and especially focuses on image analysis technology. Navigator has to always confirm the information from marine electronic navigation devices and then they compare with the view of outside targets of the windows. During this 'head down' posture, they feel uncomfortable and sometimes it cause near-accidents such as collision or missing objects, because he or she cannot keep an eye on the front view of windows. Augmented reality can display both of information of virtual and real in a single display. Therefore we tried to adapt the AR technology to help navigators and have been studied and developed image pre-processing module as a previous research already. To analysis the outside view of the bridge window, we have extracted navigational information from the camera image by using image processing. This paper mainly describes about recognizing ship feature by haar-like feature and filtering region of interest area by AIS data, which are to improve accuracy of the image analysis.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.85-89
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• 2017

One of the most challenging issues in the oil and gas industry is corrosion assessment and management in subsea structures or equipment. At present, almost all steel pipelines are sensitive to corrosion in harsh working environments, particularly in salty water and sulphur ingress media. Nowadays, the most commonly practiced solution for a damaged steel pipe is to entirely remove the pipe, to remove only a localized damaged section and then replace it with a new one, or to cover it with a steel patch through welding, respectively. Numerous literatures have shown that fiber-reinforced polymer-based composites can be effectively used for steel pipe repairs. Considerable research has also been carried out on the repair of corroded and gouged pipes incorporated with hybrid natural fiber-reinforced composite wraps. Currently, further research in the field should focus on enhanced use of the lesser and highly explored hybrid-biocomposite material for the development in corrosion prevention. A hybrid-biocomposite material from renewable resource based derivatives is cost-effective, abundantly available, biodegradable, and an environmentally benign alternative for corrosion prevention. The aim of this article is to provide a comprehensive review and to bridge the gap by developing a new hybrid-biocomposite with superhydrophobic surfaces.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.730-736
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• 2014

Test standards for electrical and electronic equipment required for ship operations is applying the IEC-60533 standard. However, although a test procedure and a specified regulation are clearly defined in the deck and bridge zone and general power distribution zone, they are not regulated in the special power distribution zone with ship propulsion system. For these reasons, the costs for additional research and development have been invested. In this paper, we was measured power noise in a special power distribution zone in ship and we were compared and analyzed values measured. The actual experiments are performed on the ship of Korea Maritime and Ocean University. As a result, the acquired data on Hanbada shows that loop antenna with low frequency band(160kHz) and ultra log antenna with high frequency band(1.97GHz)occur about 6-8dB differences and about 8.7 difference respectively. Also, the acquired data on Hannara shows that each loop antenna of 1MHz, 11MHz, and 25MHz occurs about 7dB difference about 4-5dB differences respectively. so standard of Special distribution zone must be specified by comparative analysis of data obtained by the experiment more.

• Journal of Navigation and Port Research
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• v.27 no.4
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• pp.425-430
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• 2003

The satellite navigation system is widely used for identifying a user's position regardless of weather or geographic conditions and also make effect on new technology of marine LBS(Location Based Service). which has the technology of geographic information such as the ENC. Generally, there are conceivable systems of marine LBS such as ECDIS, or ECS that use the ENC itself with powerful processor in installed type on ships bridge. Since the ENC is relatively heavy structure with dummy format for data transfer between different systems, we should reduce the ENC to small and compact size in order to use it in mobile platform. In this paper, we assumed that the mobile system like PDA, or Webpad can be used for small navigation or information system in marine field. We considered the reduction of the ENC size to make them fit well to small capability of mobile platform. However, the ENC should be updated periodically by update profile data produced by HO. If we would reduce the ENC without a consideration of update, we could not get newly updated data furthermore. As summary, we studied considerations for ENC reduction with update capability. It will make the ENC be useful in many low performance platforms for various applications.