• Journal of Navigation and Port Research
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• v.26 no.4
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• pp.441-447
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• 2002

The importance of utilization of ocean space is increased due to high population and narrow land space. The development of a new technology for future use of ocean space, such as a design technology of Very Large Floating Structures(VLFS) is needed. This paper introduces the rime history analysis of superstructures on very large floating structures and proposes the estimation method of time displacement history considering wave loads. The dynamic responses of superstructure according to variation of period and amplitude are analysed using an example frame structure and the dynamic structural safety of VLFS pilot superstructure is evaluated.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.3
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• pp.135-142
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• 2015

Floating offshore structures should be designed by considering the most extreme environmental loadings which may be encountered in their design life. The most severe loading on a wave-offshore wind hybrid power generation system is wave loads. The principal parameters of wave loads are wave length, wave height and wave direction. The wave loads have different effects on the structural behavior characteristic depending on the combination of wave parameters. Therefore, the process of investigation for critical loads based on the individual wave loading parameter is need. Namely, the equivalent design wave should be derived by finding the wave condition which generates the maximum stress in entire wave conditions. Through a series of analysis, an equivalent regular wave height can be obtained which generates the same amount of the hydrodynamic loads as calculated in the response analysis. The aim of this study is the determination of equivalent design wave regarding to characteristic global hydrodynamic responses for wave-offshore wind hybrid power generation system. It will be utilized in the global structural response analysis subjected to selected design waves and this study also includes an application of global structural analysis.

• Journal of the Korea Concrete Institute
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• v.27 no.1
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• pp.29-35
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• 2015

Recent studies to develop Very Large Floating Structure(VLFS) has shown that the construction procedure of the structure needs to acquire precast concrete module connection system using prestressing. However, the loads occurring on water are complex combinations of various condition, so the safe and stable performance of the module joints and bonding materials are key to the success of the construction. Therefore, micro-silica mixed aqua-epoxy development was introduced in Part 1 using a bonding material developed in this study. The performance of the micro-silica mixed aqua-epoxy(MSAE) applied joint of concrete module specimens connected by prestressing tendon was evaluated to verify the usability and safety of the material. RC beam, spliced beam connected by prestressing tendon and MSAE, and continuous prestressed concrete beam were tested for their initial cracking and maximum loads as well as cracking procedure and pattern. The results showed that the MSAE can control the stress concentration effect of the shear key and the crack propagation, and the maximum load capacity of MSAE joint specimens are only 5% less than that of continuous RC specimen. The details of the study are discussed in detail in the paper.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.225-226
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• 2019

육상에서 발생한 부유쓰레기는 하천을 통해 해상으로 유입되어 선박 프로펠러 파손, 항로 점유 등 선박 운항 안정성에 지대한 영향을 미친다. 본 연구는 육상 기인 부유쓰레기의 해양 확산을 방지하고 나아가 선박 운항 안정성 확보를 위한 차단막과 차단막의 부유쓰레기 차단 성능 확보를 위한 플랫폼 및 계류, 앵커시스템 개발을 연구 목표로 한다. 본 구조물의 우선 설치 대상 해역은 가덕도 남동부 해안으로, 우천시 혹은 태풍 내습시 육상에서 발생하는 많은 해양쓰레기의 확산이 이루어지는 지역이다. 대상 해역의 환경하중 조건에서 플랫폼이 정상기능을 수행하도록 수치해석 기법을 기반으로 플랫폼 및 계류, 앵커시스템을 설계하고 설계 기준 적합성을 평가하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.118-119
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• 2013

마리나 시설 내 계류된 선박 및 레저장비를 악천 후 해상상태와 선박 운항에 의해 발생된 파로부터 장비 및 인명의 안전을 위한 파 제거 장치가 필요하다. 본 연구에서는 국내 각 지자체의 수요에 부응하고 시설 및 인명의 안전을 위한 소파 시스템개발을 목적으로 시제품 제작(설계, 해석, 수조시험 등 수행완료)하였다. 실해상 성능시험에서 항주파의 발생을 위해 시험선박 선정하였으며, 소파장치 전후의 파고계측 등을 위해 부가물을 계측하여 파고를 촬영 및 계측하였다. 개발된 소파장치의 실해상 시험임을 감안해 해상 주위의 조류, 풍속, 인근 해역에서 오는 파랑변형 등에 따른 파랑요소를 고려하여 시험하였다. 부소파제는 약 40~80% 의 에너지 감소율을 보였으며, 유의파고 조건에서 42%의 에너지 감소율을 보였다.

• Journal of Environmental Impact Assessment
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• v.28 no.5
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• pp.457-470
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• 2019

This study aims to present the characteristics of marine physics, water quality, and sediment quality around offshore wind farm near the Gochang and Buan sea areas through the analysis of monitoring data. The relationships between suspended solid and wave height as well as suspended solid and flow velocity were analyzed. We found that Correlation Coefficient values of 0.61~0.69 between wave height and suspended solid, and suspended solid concentration reaches 75 mg/L or higher when wave height of more than 1m occurred in the spring (1 month). The water quality index (WQI) was used to identify the status of the water quality in the study area. Most of the measured points were rated first grade (very good). The variation of chlorophyll-a was relatively hight compared to the other criteria, indicating that it is a major factor affecting the quality index. In the sediment column, all heavy metals were detected below the Threshold Effects Level(TEL), and ignition loss and grain size show a positive correlation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.250-255
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• 2016

Ocean environmental data such as tide, wind, significant wave height etc. along the expected route were collected and analyzed to secure the safe towing and installation of floating pendulum wave energy converter(FPWEC) at planned sea area. Data from Korea Meteorological Administration(KMA) and Korea Hydrographic and Oceanographic Agency(KHOA) were reviewed and those were used to estimate the external forces exerting on the FPWEC during the towing operation. ANSYS system was used for the structural analysis of the FPWEC which is subject to complex environmental load to confirm the safety.

• New & Renewable Energy
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• v.17 no.3
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• pp.16-23
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• 2021

Recently, the Korean government announced a plan to activate renewable energies, with focus on clean energy sources such as solar and wind power as the core and the goal of achieving carbon neutrality by 2050. Unlike other photovoltaic (PV) systems, offshore PV installations are advantageous for large-scale expansion because of the ease of securing sites; they also enable lowering the power generation costs based on construction of large-scale power facilities of megawatt class or higher owing to low noise and landscape damage. However, any power generation should proceed with consideration of the special environmental conditions of the ocean. Above all, when installing large-scale facilities, it is important to reduce fluctuations of the structure and secure stability to actively respond to waves. This study is concerned with the development of a floating body technology that actively responds to waves so as to enable commercialization of offshore solar power. A unit platform for research and development on offshore PV generation was installed in the Saemangeum sea, and the structural fluctuations and stability were analyzed to ensure conformity with the major performance indicators.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.64-76
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• 1999

In this paper hydroelastic experimental techniques of very large floating offshore structures are suggested based on the model test carried out in the UOU Ocean Engineering Wide Tank. The prototype is a box-shaped floating structure with length of 300m, breadth of 60m, depth of 2m and draft of 0.5m and longitudinal bending rigidity as $4.87{\times}10^{10}kgm^2$. The scale ratio is 1/42.857. The model is realized by aluminum square pipes with the section dimension of $20mm{\times}20mm$. The numbers of longitudinal and transverse pipes are 7 and 35 respectively. Heave motions at selected points are measured with potentiometers and bending moments with strain gages.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.3
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• pp.461-467
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• 2016

In order to install the floating transport type wind-turbine foundation, water pumping is used to sink the foundation. During this process, its mass and center of gravity, and buoyancy center become continuously changed so that the dynamic stability of the floating foundation become unstable. Dynamic stability analysis of the floating foundation is a complex problem since it should take into account not only the environmental wave, wind, and current loads but also its weight change effect simultaneously considering six-degree-of-freedom motion. In this study, advanced numerical method based on the coupled computational fluid dynamics (CFD) and multi-body dynamics (MBD) approach has been applied to the dynamic stability analysis of the floating foundation. The sloshing effect of foundation internal water is also considered and the floating dynamic characteristics are numerically investigated in detail.