• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.06a
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• pp.211-212
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• 2022

지구온난화에 따른 우리나라 주변 환경의 변화와 최근 중국 불법어선의 연근해 어업자원의 고갈 등으로 인해 우리나라 연근해 어족자원을 보호할 필요성이 증대되고 있으며, 지속 가능한 어업을 위해서는 어획물의 종류와 양을 정확히 파악하고 불법 어업에 대한 철저한 감시 및 관리가 필요하다. 시공간적으로 다양하게 변하는 생태 및 어장 환경 정보와 선박에 대한 정보를 통해 해양관측과 위성 원격탐사를 동시에 이용함으로써 근해와 원양 생물자원 실태를 관측하는 것이 가능하다. 본 연구에서는 야간 불빛 위성 Suomi-NPP (Suomi National Polar-orbiting Partnership) 및 후속위성인 NOAA-20의 VIIRS (Visible Infrared Imaging Radiometer Suite) DNB (Day & Night Band) 영상을 이용하여 야간 불빛을 활용하고자 한다. 이 불빛 위성 자료를 이용하여 야간에 조업하는 어선 선단의 공간 분포를 분석할 수 있다. 또한 이 불빛 위성 자료와 AIS 자료를 상호 비교하여, 불빛 위성 자료를 통해 실제 선박의 위치 정보를 검색하는 것이 가능함을 검증하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.105-117
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• 2002

In the design of foundations for the super-structures such as transmission towers and oil-platforms, the foundations must be considered as a medium to resist cyclic tensile forces. In this study, the uplift capacity of the drilled shaft used as the medium resisting to this pattern of forces is investigated by performing cyclic uplift test of a small model-drilled shaft constructed in compacted granite soil in a steel chamber. In this test, the behavioral difference between a pile loaded on the top of the pile and a pile loaded at the bottom of the pile was investigated intensively. The load transfer curves obtained from the test were investigated by changing the confining pressure in the chamber. The load tests also included creep test and cyclic test. It is found from the tests that uplift capacity of the shaft loaded at the bottom is greater than that of the shaft loaded on the top of the pile. It is found also from the creep test that the pile loaded at the bottom was more stable than the shaft loaded on the top. If a pile loaded at the bottom is pre-tensioned, the pile will be most effective to the creep displacement. It is found also from the cyclic tests that apparent secant modulus obtained in a cycle of the load increases with the number of cycles.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.3
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• pp.180-201
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• 2020

It has been widely known that the effect of diffracted waves at the tip of composite breakwater with finite length causes the change of standing wave height along the length of breakwater, the spatial change of wave pressure on caisson, and the occurrence of meandering damage on the different sliding distance in sequence. It is hard to deal with the spatial change of wave force on trunk of breakwater through the two-dimensional experiment and/or numerical analysis. In this study, two and three-dimensional numerical techniques with olaFlow model are used to approach the spatial change of wave force including the impulsive breaking wave pressure applied to trunk of breakwater, the effect of rear region, and the occurrence of diffracted waves at the tip of caisson located on the high crested rubble mound. In addition, it is thoroughly studied the mean wave height, mean horizontal velocity, and mean turbulent kinetic energy through the numerical analysis. In conclusion, it is confirmed that the larger wave pressure occurs at the front wall of caisson around the still water level than the original design conditions when it generates the shock-crushing wave pressure checked by not two-dimensional analysis, but three-dimensional analysis through the change of wave pressure applied to the caisson along the length of breakwater.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.121-122
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• 2019

차도선과 같은 연안 화물 여객선에는 필수 탑재 항해통신장비 이외에 유지보수 지원이나 운항 효율 향상을 위한 장비는 거의 탑재 되어 있지 않은 상황으로 ICT 기술 기반 운영 및 유지보수(O&M, operating and maintenance) 지원 서비스 제공 시스템 도입이 필요하다. 이에 중소형 선박 기자재의 데이터 수집, 통합, 분석을 통해 선박 관리, 유지보수 지원, 운항 모니터링 등의 스마트 O&M 서비스를 제공하기 위한 시스템의 개발을 진행 중에 있다. 개발하는 시스템은 빅데이터 분석 기술, 모바일 어플리케이션 개발 기술, 증강현실(AR) 기술을 기반으로 선박을 구성하는 요소의 상태 모니터링, 최적 관리, 원격 유지보수 지원 등의 서비스를 제공할 예정이다. 또한, 클라우드 기반 육해상 통합 O&M 서비스 지원 시스템의 개발을 통해 선단 단위 분석, 중소형 해운선사 소모품 관리 및 운영 지원 등 종합적인 부가 서비스를 제공하는 것이 목적이다. 이러한 시스템의 개발이 완료되면, 실선 시험을 통해 개발 시스템과 서비스의 유용성을 검증할 계획이다. 본 논문에서는 이러한 O&M 지원을 위한 시스템에 관해 소개하고, 앞서 언급한 각종 서비스를 제공하기 위한 선박 및 육상 측 구성요소 정의와 서비스 아키텍처의 설계에 관한 내용을 다룬다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.366-368
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• 2022

지구온난화에 따른 우리나라 주변 환경의 변화와 최근 중국 불법 어선의 연근해 어업 자원의 고갈 등으로 인해 우리나라 연근해 어족자원을 보호할 필요성이 증대되고 있으며, 지속 가능한 어업을 위해서는 어획물의 종류와 양을 정확히 파악하고 불법 어업에 대한 철저한 감시 및 관리가 필요하다. 이러한 시공간적으로 다양하게 변하는 생태 및 어장 환경 정보와 선박에 대한 정보를 통해 해양관측과 위성 원격탐사를 동시에 이용함으로써 근해와 원양 생물자원 실태를 관측하는 것이 가능하다. 본 연구에서는 NOAA-20 위성의 VIIRS (Visible Infrared Imaging Radiometer Suite) DNB (Day & Night Band) 영상을 기반으로 추정한 야간 불빛 자료를 활용하고자 한다. DNB 불빛 영상은 낮은 조도의 불빛을 감지하여 그 정보를 보여 준다. 야간 불빛 자료에 포함된 구름 부분을 마스킹하기 위해 NASA의 신규알고리즘이 적용된JPSS-JRR-CloudMask 기술을 이용하였다. 이번 연구에서는 구름의 영향이 없는 날짜를 선별한 후 AIS 정보에서 어선의 정보를 추출하여 검증 자료로 사용하였다. 실제 선박의 정보를 이용한 위성 불빛 자료의 검증을 통해 위성자료의 신뢰성을 확보하고 향후 불빛과 선단 규모의 상관관계 분석 및 어선의 분포 경향 분석을 통하여 우리나라의 어장환경 분석에 활용 가능할 것으로 기대한다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.140-144
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• 2002

In this paper, the plastic zone size ahead of the crack tip of DENT specimen and the crack growth length under cyclic loading were measured by ESPI system. These results of the plastic zone size measured by ESPI system were compared with the plastic zone size proposed by Irwin. The results of tile crack growth length measured by it were also compared with them measured by the image analysis system. It is confirmed that it is possible to measure the plastic zone and crack growth length.

• Journal of Ocean Engineering and Technology
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• v.16 no.6
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• pp.71-75
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• 2002

In this paper, a study on the principal performance of the purse seiner ship in two vessel formations was conducted. For this task, the outline of the purse seiner fishing system in two vessel formations was reviewed. At the same time, based on the general arrangement plan, hull from of the main vessel was developed. And the stability and ship motion characteristics of the ship design were estimated. Finally, to verify the characteristics of the resistance and self-propulsion coefficient, a model test in a circulating water channel was performed. As n result, it is anticipated that this presentation will be used as the foundation material for research of purse seiner.

• Journal of Ocean Engineering and Technology
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• v.16 no.4
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• pp.13-18
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• 2002

The magnitude of the plastic zone around the crack tip of DENT(Double Edge Notched Tension) specimen and the crack growth length under cyclic loading were measured by ESPI(Electronic Speckle Pattern Interferometry) system. The measured magnitude of plastic zone was compared with the equations proposed by Irwin and calculated by a nonlinear static method of MSC/NASTRAN. The measured crack growth length by ESPI system was also compared with the obtained data by the image analysis system. From the study, it is confirmed that the plastic zone and crack growth length can be measured accurately with the high-tech equipment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.6
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• pp.325-331
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• 2022

Hydrogen embrittlement in metals has been a serious issue with regard to structural safety. In this study, molecular dynamics simulations revealed that the aggregation of hydrogen atoms at the crack tips suppresses the dislocation emission and thus results in cleavage fracture. A series of molecular dynamics simulations were performed considering factors such as the concentration of hydrogen atoms, loading rate, and diffusion coefficient. We investigated the conditions that minimize hydrogen embrittlement. The simulation results were consistent with the experimental results and used to quantify hydrogen embrittlement.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.50-61
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• 2002

This paper - following 'Functional requirement of marine waste cleaning ships and organization of the fleets'[1] - describes on the preliminary conceptual design procedure for the multi-purpose marine waste cleaning system for shallow waters. The working area of this system is Yellow Sea and part of South Sea of South Korea. As the first step, we determined the functional requirements including the daily target of waste collecting. Then, the preliminary conceptual design and general arrangements were carried out. In order to evaluate the safety and efficiency of this designed system, the stability check and the computer graphic simulation were carried out. Finally, the sea trial performance test of integrated systems in Yeosoo ports was performed and the designed system was shown its validity and effectiveness.