• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1541-1545
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• 2009

홍수 기간 중 부유잡목에 의한 수위상승 원인은 크게 상류부에서 이송되어진 유송잡물에 의한 교량 등의 수공구조물에 집적으로 인한 통수능 부족에 의하여 발생되는 수위상승과 하천내 수공 구조물의 부적절한 설계 및 시공으로 인한 수위상승으로 구분되어 진다. 현재 교량의 여유고 산정에 사용되는 홍수위는 통수능을 고려하지 않은, 하천정비계획에 사용되는 홍수위를 적용하고 있으며, 다만 통수능의 확보를 위하여 경간장에 대한 제한을 두고 있을 뿐이다. 중소하천에 위치하는 교량의 경우, 여유고 확보에 대한 기준을 적용함에 있어서 교량이 위치한 하천 단면에서의 통수능의 영향이 고려되어야 유수의 월류에 대한 위험성을 줄일 수 있다. 더욱이 하천설계기준(2005)에서는 고정 홍수량에 의한 여유고 산정치를 제안하고 있을 뿐이기 때문에, 하천설계기준에서 교량과 관련된 여유고도 하상변동과 만곡부에 의한 수위 상승, 유송잡물에 의한 통수능 영향, 계산오차 등을 고려하여 충분한 여유고를 확보하도록 보완할 필요가 있다. 본 연구에서는 부유잡목에 의한 수위상승 원인을 분석을 하고, 이에 따른 수리모형실험을 통하여 부유잡목의 높이/폭(H/B)변화에 의한 수위상승, 부유잡목의 형태별 수위상승, 교각사이 개도비에 따른 수위 상승량을 산정하여 기존의 여유고에 대한 추가적인 여유고를 확보하여 홍수시 통수능을 확보하고자 하였다. 부유잡목의 형태에 따른 수위상승량을 산정하기 위하여 개도비를 70%로 고정한 후, Fr수를 변화시켜 부유잡목의 높이/폭(H/B) 형태에 따라 산정한 결과, 부유잡목이 존재하지 않는 상태에 비하여 부유잡목에 의한 영향으로 인한 수위증가율이 Fr값이 클수록 더욱 크게 나타났으며, 부유잡목이 동일면적인 경우 폭(B)에 비하여 높이(H)가 커질수록 수위 상승이 크게 나타났다. 또한, Fr수 변화에 따른 최고수위 상승율을 구하였을 때, 상류조건에서 Fr < 0.5 인 경우는 기존 여유고에 대하여 최대 10%의 여유고를 추가 확보하며, 0.5 < Fr < 1 인 경우는 기존 여유고에 대하여 최대 20%의 여유고를 추가 확보하도록 설계하는 것이 바람직하다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.2
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• pp.109-117
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• 2022

There has been an increasing number of studies on photovoltaic energy generation system in an offshore site with the largest energy generation efficiency, as increasing the researches and developments of renewable energies for use of offshore space and resources to replace existing fossil fuels and resolve environmental challenges. For installation and operation of floating photovoltaic systems in an offshore site with harsher environmental conditions, a stiffness of structural members comprising the total system must be reinforced to inland water spaces as dams, reservoirs etc., which have relatively weak condition. However, there are various limitations for the reinforcement of structural stiffness of the system, including producible size, total mass of the system, economic efficiency, etc. Thus, in this study, a floating breakwater is considered for reducing wave loads on the system and minimizing the reinforcement of the structural members. Wave reduction performances of floating breakwaters are evaluated, considering size and distance to the system. The wave loads on the system are evaluated using the higher-order boundary element method (HOBEM), considering the multi-body effect of buoys. Stresses on structural members are assessed by coupled analyses using the finite element method (FEM), considering the wave loads and hydrodynamic characteristics. As the maximum stresses on each of the cases are reviewed and compared, the effect of floating breakwater for floating photovoltaic system is checked, and it is confirmed that the size of breakwater has a significant effect on structural responses of the system.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.73-74
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• 2000

어업용 프레임 구조물 중 부유식의 것은 수면에 떠 있는 프레임과 그 하부에 있는 그물이 조류와 파랑에 의한 저항을 동시에 받고, 낙망 등과 같은 수중 침하식의 것은 그 전체가 조류에 의한 저항을 많이 받기 때문에, 이들 구조물의 안전성은 그들이 받는 저항의 크기에 따라 크게 달라진다. (중략)

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2002.11a
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• pp.133-138
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• 2002

Recently, mega-float offshore structure is studied as one of the effective utilization of the ocean space. And mega-float structure are now being considered for various applications such as floating airports, container yard, offshore cities and so on. This mega-float structure is relatively flexible compared with real floating structures like large ships. when we estimate dynamic responses of these structures in waves, the elastic deformation is important, because vertical dimension is small compared with horizontal. The analysis of the dynamic response as it receives regular wave is studied. The finite element method is used in the analysis of structural section of this model. And the analysis is carried out using the boundary element method int eh fluid division. In order to know the characteristics of the dynamic response of the mega-float structures, effects of wavelength, water depth, and wave direction on dynamic response of the floating structure are studied by use of numerical calculation.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.66-74
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• 2000

In this paper, hydroelastic responses of the very large floating structure are studied based on the linear potential theory. A theoretical method is developed to analyze the hydroelastic reponses of very large floating structures(VLFS) using the pressure distribution method and the modal expansion method. The singularities distributed on a zero draft plate at the free surfaces and hydrodynamic pressures are evaluated. The deflections of structure are expanded approximately in terms of natural mode functions of free-free beam. The calculated items are pressure distributions. vertical motions, hydrodynamic coefficients and bending moments of VLFS. The numerical results are compared with those measured by experiments.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.72-80
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• 2015

In this study, comparative analysis has been performed with regard to a bending stress and deformation at bottom slab of a concrete floating container terminal by live load distributions. In addition, a structural performance and behavior of the floating structure is considered using a numerical analysis. Through reviewed structural performance of a floating structure by live load distribution, the structure presented tensile behavior by two live load cases (A, B, D-type). Then, the other live load cases (C, E, F, G, H, I, J-type) shows compressive behavior. Especially, immoderately compressive stress was generated on bottom slab at specific load distribution. but, that should be decreased through controling buoyancy pre-flexion. Through reviewed structural behavior, slopes of structure by four live load cases (B, E, F, H-type) were exceeded in design criteria of mega-float. It should be estimated that it get out of the load case at loading container. In all, the present study can be considered as a benchmark of a floating container terminal in the absence of analysis and will be used to guide-line about serviceability of concrete floating container terminal.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.698-702
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• 2005

Natural modes and responses of floating structures under wave loads are analyzed by direct method considering the stiffness of unit connections. Tow types of connection such as tandem connection and side by side connection are considered in numerical examples. By analyzing natural modes and connection forces, influences of connection stiffness on responses of floating structures are investigated.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.63-68
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• 2000

A very large floating structure has rather small motion characteristics as to the whole body, while the motion at end part of such structure becomes largest due to the elastic motion of the structure. This paper presents on the theoretical result on the relative motion characteristics and green water phenomena of VLFS in waves This phenomena affect not only to strength of the structure but also the determination of depth of structure. To predict motion responses of structure in regular waves, the source-dipole distribution method and F.E.M is used By irregular wave results, the probability of occurrence of green water and response of the structure were calculated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.132-140
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• 2006

This paper investigates the characteristics of dynamic responses of floating structures with connections under sea wave loads. Direct method using higher order boundary element method (HOBEM) and finite element method (FEM) is adopted for numerical analysis. A 500 m-long and 250-m width very large floating structure (VLFS) with four units are considered in numerical analysis. Hinge connection and spring connection with various strength are considered as connection types. Displacements and stresses of VLFS according to the connection types are compared considering wave period and heading angle reduction.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.147-158
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• 1999

Warm or waste water discharged from offshore-based facilities often causes environmental polution as it is transported to coastal area due to tidal actions. In this research a floating-type current control structure is introduced in order to reduce the pollutant spreading in the coastal area. Effectivenss of the structure is investigated through the numerical experiment which is based on a 3-D finite difference multi-level scheme. The warm-water spreading in the bay is reduced when the draft of the structure increases and its optimum draft is found to be between 0.25h and 0.65h, where h is the water depth. The proposed structure is also tested in the Gohyun Bay and it ts proven to be applied to controllling pollutant spreading if its draft is properly chosen.