• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.287-295
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• 2018

The ichthyoplanktons were sampled to study distribution of the ichthyoplankton in coastal waters of Nanji-Island in August and November 2015 and January and May 2016. During the study, fish eggs of eight different species were collected. Engraulis japonicus was the most dominant species which accounted 44.80%. Sebastes schlegeli comprised 31.39% of the total larvae and juveniles. The diversity index of species per month of the collected juveniles at Nanji Island from 2015 to 2016 was 0.598-1.770 and the evenness index was 0.432-0.761. In case of dominance index was 0.619-0.897 against the evenness index. The analyzed species diversity index by the each station was 0.818-1.945 and the dominance index was 0.492-0.897 against the species diversity index. The months of August and May exhibited similar results. In addition, the community structure was very similar in state 2 and state 3.

• Wind and Structures
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• v.29 no.4
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• pp.225-234
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• 2019

Conductor galloping is a common disaster for the transmission lines. Among the existing analytical methods, the wind tunnel test is highlighted as the most effective approach to obtain the aerodynamic coefficients. In this paper, the aerodynamic coefficients of 12 conductor models covered with the crescent-shaped ice, which were fabricated considering the surface roughness of the iced conductor, were obtained based on the wind tunnel test. The influence of the Reynolds number and the shape parameter ${\beta}$, defined as the ratio of ice thickness to the diameter, were investigated. In addition, the effect of surface roughness of the iced conductor was discussed. Subsequently, unsteady areas of conductor galloping were calculated according to the Den Hartog criterion and the Nigol criterion. The results indicate that the aerodynamic coefficients of iced conductors change sharply at the attack angles of $20^{\circ}$ and $170^{\circ}$ with the increase of ${\beta}$. The surface roughness of iced conductors changed the range of attack angle, which was influenced by the increase of the Reynolds number. The experimental results can provide insights for preventing and controlling galloping.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.283-296
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• 2020

A numerical model is established to investigate the run-up of a solitary wave after propagating over a triangular saw-tooth-shaped submerged breakwater. A rectangular-shaped submerged breakwater is simulated for comparison. Several factors, including the submerged depth, the lagoon length and the beach slope, are selected as independent variables. The free surface motions and velocity fields of the solitary wave interacting with the submerged breakwater are discussed. The results show that the submerged depth and lagoon length play significant roles in reducing the run-up. The influence of the beach slope is not significant. At the same submerged depth, the triangular saw-tooth-shaped submerged breakwater has only a slightly better effect than the rectangular-shaped submerged breakwater on the run-up reduction. However, a calmer reflected wave profile could be obtained with the rougher surface of the saw-tooth-shaped submerged breakwater. The study conclusions are expected to be useful for the conceptual design of saw-tooth-shaped submerged breakwaters.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.2
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• pp.61-68
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• 2018

This study was conducted to propose the optimum minimum requirement of cutoff system composed of the impermeable soil layer and vertical barrier in offshore landfill for prevention pollution leakage by seepage, advection, and dispersion numerical analyses under steady state. According to the study results, the minimum requirement of impermeable soil layer is below $1{\times}10^{-6}cm/s$ of hydraulic conductivity with more than 500 cm thickness or a system with equivalent cutoff effect. The minimum requirement of vertical barrier is below $1{\times}10^{-6}cm/s$ of hydraulic conductivity with more than 50 cm thickness or a system with equivalent cutoff effect. In addition, the vertical barrier should be embedded enough to seal securely with the impermeable soil layer for working cutoff effect.

• Journal of Korean Society of Rural Planning
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• v.4 no.1
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• pp.63-74
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• 1998

The objective of this study is the investigation and analysis of information on the conservation and the sustainable use of coastal wetlands based on the awareness of local residents in Kang-hwa island, Tae-an and Seo-chon. The results are summarized as follows: The degree of the satisfaction on the natural environment is in the order of Tae-an, Kang-hwa and Seo-chon. This order is accorded with the order of the goodness of natural environment. The order for the degree of the satisfaction on the living environment is same as the order for the satisfaction degree on the natural environment. Especially, residents of Seo-chon are not satisfied with the living environment. The residents of all regions are not satisfied with the socio $.$ economic environment. The local resident of Kang-hwa and Tae-an, where natural environment is well-conserved, prefer conservation to development of the region. On the other hand, the local residents of Seo-chon have relatively low preference for conservation of the region. These results show the following consideration for the ideal method of management for the conservation and sustainable development of coastal wetlands. In case of Kang-hwa island, where the, condition the natural environment is well conserved, should be managed with the minimum development with maintenance of the current state must be driven.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.2
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• pp.75-87
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• 2013

This study developed a GIS-based suitability assessment model of coastal zoning system that is needed in the substantial classification of coastal zoning system according to the establishment of law about coastal zoning system. First, this study investigated several kinds of regulations, GIS database and application system related coastal area. Also, grid data model was selected as the GIS analytical model for calculating items of suitability assessment of coastal zoning system. And Grid-based analytical method was suggested for calculating items composing of sea and spatial location characteristics including physical one. Critical values of items were presented using standards that were suggested in coastal regulations and land suitability assessment. Especially, this study presented a calculation method of continuous pattern as fuzzy set function for reflecting the characteristics of GIS data. And this study classified the suitability grade using Z-score and developed model designating coastal zone as conservation management priority, utilization management priority, and planning management priority. This study is judged that very efficient business performance is possible if we consider the spatial coverage of study area and GIS database when the suitability assessment model of coastal zoning system that is suggested in this study, is applied to business works.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.1-18
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• 2009

A series of three-dimensional numerical simulations using a generalized multidimensional hydrodynamic dispersion numerical model is performed to simulate effectively and to evaluate quantitatively impacts of urbanization on density-dependent groundwater flow and salt transport in a coastal aquifer system, Suyeong-Gu, Busan, Korea. A series of steady-state numerical simulations of groundwater flow and salt transport before urbanization with material properties of geologic formations, which are established by numerical modeling calibrations considering all the urbanization factors, is performed first without considering all the urbanization factors. A series of transient-state numerical simulations of groundwater flow and salt transport after urbanization is then performed considering the urbanization factors individually and all together. Finally, the results of both numerical simulations are compared with each other and analyzed. The results of the numerical simulations show that density-dependent groundwater flow, salt transport, and seawater intrusion in the coastal aquifer system are intensively and extensively impacted by the urbanization factors. Especially, these urbanization factors result in the changes of the total groundwater volume and salt mass in the coastal aquifer system. However, such impacts of each urbanization factor are not spatially uniform but locally different.

• The Journal of Fisheries Business Administration
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• v.37 no.3 s.72
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• pp.131-155
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• 2006

연안관광여행과 레크레이션은 일반적으로 스노클링, 다이빙, 레포츠피싱, 해변방문, 보우팅, 크루져 등의 연안근처에서 이루어지는 모든 레크레이션 활동을 포함한다. 2000년에 바다와 관련된 산업은 미국에 1,170억 달러를 기여했고, 200만개의 직업을 창출하였다. 그 중 직업의 75%와 경제적 가치의 50%는 해양관련 관광과 레크레이션에 의해 생산되었으므로 연안관광과 레크레이션은 미국경제에서 커다란 부분을 차지하고 중요하다고 할 수 있다. 본 연구는 미국에서 연안관광과 레크레이션이 가지는 중요성에 대하여 설명하고 이에 따른 연안관광여행에 대해 현재 사용 및 적용되고 있는 미국의 정책구조를 정리하고, 이와 관련된 기관들과 그 역할에 대하여 분석하였다. 또한 연안 레크리에이션 관리가 미국내의 연방, 주, 지역정부차원에서 어떠한 방식으로 이루어지는지에 대하여 분석하였다. 레크리에이션 자원 관리의 개념으로부터의 연방 및 주의 연안 프로그램의 문제점 및 상황과 관광 여행 개발을 위해 사유지 부분 접근문제해결에 대하여 연방 및 지방 정부의 대응방법을 분석함으로써 미래 연안관광자원의 이용을 위한 이론적 기본틀을 제시하고 있다.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.20-28
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• 2017

The steady-state, incompressible and three-dimensional numerical analysis was performed to investigate the flow fields around the seabed tiller used for soil improvement in coastal fisheries and the pulling force and buoyancy generated by tiller operation. The turbulence model used in this study is a realizable $k-{\varepsilon}$. As a results, at a stationary current or a current speed of 1.2 knots, where rotor rotates in a clockwise direction, a typical vortex pair appears near the tip of the rotor except for the edge, and the strength of the vortex pair increases with the number of revolutions of the rotor. The pulling force of the tiller rotating in the counterclockwise direction increases with the number of revolutions. Also, when the current flows at 1.2 knots and the rotor rotates clockwise, the pulling force of the tiller acts on the upstream side irrespective of the number of rotations of the rotor, so that no force is applied. The buoyancy of the tiller acts on the seawater surface if the flow direction inside the rotor is the same as the direction of rotation of the rotor, regardless of the current velocity, otherwise it acts on the seabed.

• Wind and Structures
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• v.21 no.6
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• pp.597-607
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• 2015

With an increasing demand of a renewable energy, new offshore wind turbine farms are being planned in some parts of the world. Foundation installation asks a significant cost of the total budget of offshore wind turbine (OWT) projects. Hence, a cost reduction from foundation parts is a key element when a cost-efficient designing of OWT budget. Mono-piles have been largely used, accounting about 78% of existing OWT foundations, because they are considered as a most economical alternative with a relatively shallow-water, less than 30 m of seawater depth. OWT design standards such as IEC, GL, DNV, API, and Eurocode are being developed in a form of reliability based limit state design method. In this paper, reliability analysis using the response surface method (RSM) and numerical simulation technique for an OWT mono-pile foundation were performed to investigate the sensitivities of mono-pile design parameters, and to find practical implications of RSM reliability analysis.