• Journal of Korean Society of Coastal and Ocean Engineers
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• 제9권2호
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• pp.63-73
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• 1997

The tidal propagation for the Southeast Asian Seas is described via a high-resolution, two-dimensional hydrodynamic model by the equilibrium tide and co-oscillating tide at the Straits. Computed tidal distributions of four major semidiurnal tides (M$_2$, S$_2$, $K_2$, $N_2$) and four major diurnal tides (K$_1$, $O_1$, P$_1$, Q$_1$) are presented and results are also compared with coastal observations archived in IHO global tidal data base (Canadian Marine Environmental Data Service) and existing tidal charts including Schwiderski GOTD(Global Ocean Tidal Data) maps.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제6권3호
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• pp.216-225
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• 1994

By use of laboratory experiment data set for an elliptic shoal by Berkhoff et al. (1982), both accuracy and Performance tests of numerical results between PCGM (Preconditioned Conjugate Gradient Method) and PA(Parabolic Approximation) are compared. Although both results show good agreement with the experimental data the PA model gives better reproduction of the relatively high amplitudes in the section 4-5 downwave of the shoal, in comparison with the PCGM. The PA model has been proved to be a useful tool for predicting wave transformationsin large shallow water region, but it can be applied only to the case of negligible reflection. On the other hand, there is a need to improve the computational efficiency of the PCGM model which is a finite difference scheme directly derived from the mild slope equation and can handle reflection. By taking the results of th PA model as an input data of the PCGM, the CPU time can be reduced by about 40%.

• Journal of Korea Water Resources Association
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• 제57권9호
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• pp.633-643
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• 2024

Many coastal countries have developed and used a wide range of technologies and policy measures to protect freshwater aquifers and groundwater resources from seawater intrusion, and have established and implemented a foundation to legally and institutionally support them. This study covers coastal states in the eastern United States, the Netheland, India and Japan. The goal of this study is to analyze each country's legal and policy measures for coastal groundwater management. By introducing Jeju Island's groundwater standard level system, we aim to provide a basis for future discussions on groundwater management measures not only in Jeju Island but also in coastal areas of Korea. As a result of the analysis, despite the various contents and aspects of coastal groundwater management based on local issues and characteristics around the world, in order to achieve the common goal of securing a stable amount of groundwater withdrawal and preventing seawater intrusion and to maximize the efficiency of groundwater management, it is understood that attempts are being made to establish optimal management measures, laws, systems, and policies based on several key factors. First, considering the hydrogeological characteristics and status of coastal groundwater, a separate special management system is being established and implemented within the scope of the national groundwater management system. In addition, preventing and maintaining groundwater level decline through limiting the amount of groundwater withdrawal and preventing seawater intrusion are key policy goals and policy tools, and it is suppored by research and development. Finally, tt was found that synergy effects are being sought by using various other policy tools and measures in a complex manner.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제20권2호
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• pp.194-202
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• 2008

In general, forecast tsunami heights announced for tsunami warning are computed by using a linear tsunami model with coarse grids which leads the underestimation of inundation area. Thus, an accurate tsunami inundation map corresponding the forecast tsunami height is needed for an emergency evacuation plan. A practical way to construct a relatively accurate tsunami inundation map was proposed in this study for the quantitative forecast of inundation area. This procedure can be introduced as in the followings: The fault dislocations of potential tsunami sources generating a specific tsunami height near an interested area are found by using a linear tsunami model. Based on these fault dislocations, maximum inundation envelops of the interested area are computed and illustrated by using nonlinear inundation numerical model. In this study, the tsunami inundation map for Imwon area was constructed according to 11 potential tsunami sources, and the validity of this process was examined.

• Proceedings of the Plant Resources Society of Korea Conference
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• 한국자원식물학회 2022년도 추계학술대회
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• pp.61-61
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• 2022

섬괴불나무(Lonicera insularis Nakai)는 인동과(Caprifoliaceae) 인동속(Lonicera) 식물로 우리나라 울릉도에 제한적으로 분포한다. 인동과 식물 중 인동(L. japonica Thunb.), 괴불나무[L. maackii (Rupr.) Maxim] 등 다수의 분류군이 약리효능이 입증되었으며, 맛이 뛰어나 차, 술, 음료 등으로 다양하게 활용되고 있다. 그 중 섬괴불나무는 최근 면역자극 및 항비만 활성 등 다양한 약효가 확인되어 약용자원으로서의 잠재적 가치가 큰 것으로 보고된 바 있다. 따라서 본 연구를 통해 특산식물인 섬괴불나무의 적정 자생지를 명확하게 구명하여 보전생물학적 연구, 재배 및 산업화와 같은 현지 외 보전연구를 위한 기초자료로 활용하고자 한다. 연구 결과, 울릉도에서 확인된 섬괴불나무의 주요 분포지는 4개소로 해안도로 일대에 자생하고 있었다. 입지환경은 해발고도 8-20 m, 사면 방위는 남사면, 경사는 15-30°로 완경사지에서 주로 자생하고 있었다. 방형구(10×10 m) 내 개체수는 5-25 개체로 대부분 군락을 이루고 있는 것으로 확인되었다. 4개 조사구에 대한 군집분석을 실시한 결과, 조사구는 곰솔 군집(Pinus thunbergii Parl.)으로 상층의 발달이 거의 없는 전형적인 해안 식생의 구조로 확인되었다. 관목층은 보리장나무(Elaeagnus glabra Thunb.), 송악[Hedera rhombea (Miq.) Bean], 머루(Vitis coignetiae Pulliat ex Planch.) 등이 경쟁관계에 있었으며, 초본층은 왕호장근[Reynoutria sachalinensis (F.Schmidt) Nakai], 갯메꽃[Calystegia soldanella (L.) R.Br], 해국(Aster spathulifolius Maxim.) 등으로 인하여 섬괴불나무는 피압된 것으로 판단된다. 군집의 안전성, 다양성을 나타내는 척도인 종다양성지수는 1.259, 최대종다양성지수는 1.286, 균재도는 0.979, 우점도는 0.021로 확인되었다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제36권3호
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• pp.95-104
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• 2024

In this study, geometric calculation was performed to investigate the influence of the combined effect of tilt and misorientation on the pullout capacity of suction anchor used in floating offshore wind turbine. When considering the combined effect of tilt and misorientation, it was observed that they do not proportionally affect the pullout capacity but rather influence each other relatively. Criteria considering both tilt and misorientation are not provided in existing literature or DNV recommendation. Therefore, based on the comprehensive results of this study, a proposed decrease in pullout capacity within 3% is suggested.

• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2007년도 학술발표회 논문집
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• pp.336-340
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• 2007

국내 산업 및 기능적 측면에서 중추역할을 수행하고 있는 부산 울산 인천 등 전체 도시의 40%를 이루고 있는 해안도시들이 하천범람과 같은 홍수피해, 해일피해 등에 대한 체계적인 대비가 전무한 실정으로서 본 연구는 모형화 기법을 이용하여 해안도시홍수 경보발령 기준안을 도출하고 이를 실 수문관측 자료를 이용한 검정을 통해 경보발령 기준안의 문제점을 파악하여 그 개선방향을 제시하였다. 대상유역은 대표적 해안도시하천의 특성을 지니고 있는 부산시 온천천유역으로 강우-수위 관측 모니터링 시스템을 구축, 운영을 통해 10분 간격 강우 및 수위 자료를 구축하였으며, 수위 자료는 수위 유량 관계곡선을 이용하여 유량으로 환산하였다. 미계측 상태에서의 수리 수문 모형화를 통해 도출된 경보발령기준안에 대한 평가 및 문제점 도출을 위해 본 연구는 유역내 실시간 수문관측을 통해 얻은 강우 및 유출 특성 자료를 이용하였다. 대상 유역내 경보발령 지점인 세병교 지점의 20분 누가기준 경보발령 기준우량은 한계수위 $H_{c1},\;H_{c2},\;H_{c4}$인 경우 각각 4mm, 5mm, 6mm로서 20개월 동안 이러한 기준을 이용하여 관측된 강우사상 중 경보발령 기준안의 평가가 가능한 26개의 강우사상을 분류할 수 있었다. 그 결과 약 60%의 강우사상(case_1)이 성공한 경보발령 기준우량 임을 관측할 수 있었으며 이러한 발생강우에 대해 $20{\sim}150$분의 대피여유시간을 확보할 수 있었다. 그러나. 경보발령에 실패한 40%의 강우사상은 발생 강우의 총강우량이 대체적으로 적은 경우 및 지속기간 동안 경보발령기준에 준하는 강우를 발생하였으나 수위에 영향이 미비하여 한계수위에 도달하지 못한 경우(case_2), 20분 누가강우는 기준에 도달하지 않았으나 강우 지속시간이 길어 이미 선행강우로 인해 경보발령 이전에 한계수위를 넘어서는 경우(case_3)로서 분석되었다. 이러한 실패한 경보발령의 경우에 대한 원인분석 결과, 기존의 모형화를 통해 고려되지 못하였던 해안도시 홍수의 특성 중 총강우량에 대한 고려, 선행강우 여부 및 강우 지속시간, 지속시간 내 강우집중도 그리고 선정지점 내 조위의 영향과 유역내 합류식 하수관거 시스템의 영향 등 자연유역과는 다른 다소 복잡한 요소를 고려한 해안도시홍수 경보발령 기준에 대한 개선이 필요함을 확인할 수 있었다.

• Journal of Korean Society of Environmental Engineers
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• 제35권10호
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• pp.687-693
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• 2013

Coastal sand dunes have been seriously damaged caused by the development thoughtless for the environment and coastal erosion and destruction due to artificial structures like coast roads and breakwater. Hereupon, in this study we made a library of rhizobacteria that have the plant growth-promoting ability for plant rhizosphere of indigenous plants inhabiting in a coastal sand dune as well as the strong tolerance to salt, and evaluated the plant growth-promoting ability of these strains. Furthermore, we evaluated the effect of rhizobacteria on the growth rate of saline tolerant plants in sandy soil; selected out the most useful micro-organism for the restoration of a damaged sand dune. The effect of inoculation of strains selected from the first experiment on the growth of Peucedanum japonicum and Arundo donaxes planted in a coastal sand dune was evaluated. As a result, Bacillus aerius MH1RS1 had plant growth promoting activities: indole acetic acid (IAA) production, siderophores and 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase) activity, and also had a salinity tolerance. Also, in case of Peucedanum japonicum, the length of stems and weights of roots were enhanced by the inoculation of B. aerius MH1RS1. Fresh weights of stems and weights of roots in experimental group were, in particular, increased by 25% comparing with the control group. For an Arundo donax in experimental group, plant length increased by 18%, and weight of roots by 20% which is significant.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제8권3호
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• pp.246-255
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• 1996

A mild slope equation of parabolic type is derived with the revision of the 2nd order differential term and a new approach for the application to large area is presented. The replacement with long waves can overcome the numerical difficulty due to small waves over the system of large grid sizes. No matter how long the replaced wave length is, the refraction and shoaling are maintained by toeing its own wave speed and group velocity, respectively. However, the diffraction effect is modified by means of Eikonal equation. The developed numerical model was applied to the shoal of Ito and Tanimoto (1972) to yield the satisfactory results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제16권2호
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• pp.103-107
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• 2004

Empirical equation has been developed by employing the new non-dimensional physical number 'wave action slope' for the estimation of breakwater armor weight. Van der Meer(1987) introduced Iribarren number for the same purpose, but his equation shows very different trend of distribution with the condition of Iribarren number. On the other hand the equation related with wave action slope keeps the same trend of distribution over the whole region. When the parameter is related to the Iribarren number, the equation of wave action slope has a very high accuracy.