• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.76-82
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• 1998

Increase of greenhouse gas due to $CO_2$ and CH$_4$ gases would cause the global warming in the atmosphere. According to the global circulation model, it is pointed out in the Okhotsk Sea that the large increase of atmospheric temperature might be occurredin this region by global warming due to the doubling of greenhouse effectgases. Therefore, it is very important to monitor the sea ice extents in the Okhotsk Sea. To improve the sea ice extents and concentration with more highly accuracy, the field experiments have begun to comparewith Airborne Microwave Radiometer (AMR) and video images installed on the aircraft (Beach-200). The sea ice concentration is generally proportional to the brightness temperature and accurate retrieval of sea ice concentration from the brightness temperature is important because of the sensitivity of multi-channel data with the amount of open water in the sea ice pack. During the field experiments of airborned AMR the multi-frequency data suggest that the sea ice concentration is slightly dependending on the sea ice types since the brightness temperature is different between the thin and small piece of sea ice floes, and a large ice flow with different surface signatures. On the basis of classification of two sea ice types, it is cleary distinguished between the thin ice and the large ice floe in the scatter plot of 36.5 and 89.0GHz, but it does not become to make clear of the scatter plot of 18.7 and 36.5GHz Two algorithms that have been used for deriving sea ice concentrations from airbomed multi-channel data are compared. One is the NASA Team Algorithm and the other is the Bootstrap Algorithm. Intrercomparison on both algorithms with the airborned data and sea ice concentration derived from video images bas shown that the Bootstrap Algorithm is more consistent with the binary maps of video images.

• Fisheries and Aquatic Sciences
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• 제7권2호
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• pp.90-95
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• 2004

An analytical model for predicting the convection-diffusion of solute dumped in a homogeneous open sea of constant water depth has been developed in a time-integral form. The model incorporates spatially uniform, uni-directional, mean and oscillatory currents for horizontal convection, the settling velocity for the vertical convection, and the anisotropic turbulent diffusion. Two transformations were introduced to reduce the convection-diffusion equation to the Fickian type diffusion equation, and then the Galerkin method was then applied via the expansion of eigenfunctions over the water column derived from the Sturm-Liouville problem. A series of calculations has been performed to demonstrate the applicability of the model.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.191-192
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• 2003

A numerical method for a wave diffraction problem in three-dimensional channels is developed. The physical models are various shapes of channel connected to the open sea. When a ship or an offshore structure is moored in various configurations of channel connected to an open sea, the prediction of the hydrodynamic force exerting on the moored ship could be important for the prediction of its motion. It is assumed that the fluid is inviscid and incompressible and its motion is irrotational. From the continuity equation, the Laplace equation can be obtained as the governing equation. The surface tension at free surface is neglected, and wave amplitude is assumed to be small compared to the wave length. Then the free surface condition can be linearized. The numerical method used here is the localized finite element method based on a variational formulation

• 수산해양교육연구
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• 제21권3호
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• pp.335-346
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• 2009

Offshore-aquaculture is a new idea, has emerged as an alternative method, which can minimize the damage to the natural disaster due to the environment pollution by the fish farming activities in the coast and overcome the problems of vicious cycle in fish farming management. On the other hand, as the current fish farming laws and institutions focus on the support for offshore-aquaculture, having the limit to revitalizing and supporting the fish farming business in the open sea, it is necessary to amend the laws and institutions related to fish farm. We should be establish in connection with offshore-aquaculture, after the study aims at examining the foreign laws and institutions in such countries as USA and Norway, establishing the methods for the future laws and institutions of open sea fish farm through the analysis of the issues and controversies in the process of enactment in Korea.

• 대한조선학회논문집
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• 제58권3호
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• pp.191-197
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• 2021

This study addresses autonomous ship collision avoidance in narrow channels using curvilinear coordinates. Navigation in narrow channels or fairways is known to be much more difficult and challenging compared with navigation in the open sea. It is not straightforward to apply the existing collision avoidance framework designed for use in the open sea to collision avoidance in narrow channels due to the complexity of the problem. In this study, to generalize the autonomous navigation procedure for collision avoidance in narrow channels, we introduce a curvilinear coordinate system for collision-free path planning using a parametric curve, B-spline. To demonstrate the feasibility of the proposed algorithm, ship traffic simulations were performed and the results are presented.

• 해양환경안전학회지
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• 제23권1호
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• pp.83-90
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• 2017

본 연구는 해수유동모델을 이용하여 하계 한국 남해안 양식장 부근에서 수온의 시 공간적인 분포를 파악하였다. 한국 남해 조류의 흐름은 창조시 서향, 낙조시 동향하며, 쓰시마 난류의 흐름은 50 m보다 깊어지는 외양에서 연안에 비해 강하게 동북향 하였다. 조류, 바람, 쓰시마 난류 및 실시간 수온을 고려한 해수유동에서 하계 수온의 분포는 반폐쇄성 해역에서 $26{\sim}28^{\circ}C$로 높게 나타났으며, 외양으로 갈수록 낮아져 $18{\sim}22^{\circ}C$로 나타났다. 반폐쇄성 내만의 형태를 가지는 해역의 해수교환량을 계산한 결과 광양만 $10,331m^3/sec$, 여수-가막만 $16,935m^3/sec$, 그리고 거제-한산만은 $13,454m^3/sec$로 나타났다. 해수교환량이 적은 해역일수록 수온이 비교적 높게 나타난다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.81-88
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• 1998

During an earthquake, there are three main components of excitation : horizontal excitation of the ground, vertical excitation of the pile due to superstructure feedback produced by vertical excitation of the ground, and the seawater excitation induced by the vertical ground shaking, that is, "the seaquake." These excitations could have effects on the soil plugs in open-ended pipe piles installed at offshore sites. In this study, seaquake excitation induced by the vertical ground shaking was simulated by pulsing the water pressure at the seabed. During a seaquake, due to induced excess porewater pressure and pressure gradients in the soil, the capacity of open-ended pipe piles installed in a simulated sea depth of greater than 220 m was reduced serevely and the soil plugging resistance was degraded by more than 80%. The soil plug was failed because of the upward seepage forces that developed in the soil plug due to excess pore water pressure produced in the bottom of the soil plug during the seaquake. The compressive capacity of an open-ended pile in a simulated sea depth of less than 220m was reduced only by about 10%, and the soil plug resistance was degraded by less than 5%.s than 5%.

• Journal of the korean society of oceanography
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• 제37권3호
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• pp.91-107
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• 2002

The wintertime upwind flow in the Yellow Sea has been investigated through a series of two-dimensional numerical experiments in an idealized basin. A total of 10 experiments have been carried out to examine the effects of wind forcing, bottom friction and the presence of oceanic currents sweeping the shelf of the East China Sea. A spatially uniform steady and periodic wind stresses are considered along with comparison of linear and quadratic formulations. The wind-driven flow in the absence of oceanic current has been computed using Proudman open boundary condition (POBC), while the wind-driven current in the presence of oceanic current has been computed using Flather’s radiation condition (FOBC). The oceanic currents to be prescribed at the open boundary have been simulated by specifying uniform sea level gradients across the Taiwan Strait and the eastern ECS shelf, Calculations show that, as seen in Lee et al. (2000), oceanic flow little penetrates into the Yellow Sea in the absence of wind forcing unless a unrealistically low rate of bottom frictional dissipation is assumed. Both steady and time-periodic wind stresses invoke the upwind flow along the central trough of the Yellow Sea, independently of the presence of the oceanic current. The presence of oceanic currents very marginally alters the north-south gradient of the sea surface elevation in the Yellow Sea. Changes in the intensity and direction of the wind-induced mean upwind flow are hardly noticeable in the Yellow Sea but are found to be significant near Cheju Island where the gradient is reduced and therewith contribution of Ekman transport increases. In case of steady wind forcing circulation patterns such as two gyres on the slope sides, a cyclonic gyre on the western slope and an anticyclonic gyre on the eastern slope persist and the upwind flow composes part of the cyclonic gyre in the Yellow Sea. While in case of the time-periodic wind stress the appearance and disappearance of the patterns are repeated according to the time variation of the wind stress and the upwind flow accordingly varies with phase delay, mostly intensifying near the time when the wind forcing is approximately near the middle of the decaying stage.

• 수산경영론집
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• 제30권2호
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• pp.1-23
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• 1999

In the Northeast Asian region fisheries agreements of the past regarding high seas as an agreement area were transformed or new agreements were introduced in order to conform to the EEZ regime. However, the existing joint regulatory zone which “open” status is somewhat similar to the high sea not only disappear, but also two new systems were established. To begin with, parties of the agreement claimed their EEZs to be from the territorial sea baselines to the extent set forth, problem of the fishery access of the other party under the agreement is to be solved on the principle of reciprocity and on recognizing of the catch results achieved in the past. In regards to the overlapping zones like neutral zone of the East Sea of Korea(Sea of Japan) and neutral zone to the south of the Cheju Island, provisional measures zones in the Yellow Sea and in the East China Sea, and transitional zone of the Yellow Sea special fisheries management systems reflecting the legal character of the zone involved are applied. Moreover, as fisheries agreements defining open sea as an agreement zone are not able to conform to the EEZ regime, so new fisheries agreements must be taken out from old systems and conceptions, and must be understood and enforced from the new point view. Therefore, countermeasures needed to do so should be developed, and their basic structure is as follows. Firstly, the basic concept of the EEZ regime requires that the coastal states have sovereign rights on their sea zones' natural resources and bear responsibilities appropriate to their allowed jurisdiction. Each Northeast Asian state should adjust the structure of fishing industries and employ advanced fisheries management system, and should make efforts toward such issues of the state policy as increasing fishery resources and preserving ocean environment. Secondly, measures should be developed to solve the international fisheries disputes which are to occur under enforcement of the new fisheries agreements system. In regards to the acts of violation the fisheries laws in the foreign EEZ the principle of jail sentence prohibition is established by the UN Convention on the Law of the Sea, and every fisheries agreement reflects this principle. Therefore, the present question is to consider concrete measures to enable the easy release of the seamen, who violated fisheries laws slightly and well-intently, through establishment and management of the guarantee fund needed to make collateral reasonable. Thirdly, Korean-Russian and Russian-Japanese fisheries relations were formed on the basis of the EEZ regime, since 1992 and 1977 respectively, and are expected to maintain mutually beneficial cooperative character. As for Korean-Chinese-Japanese fisheries relations, the operational problems of overlapping zones, and problem of the permits for EEZ mutual access should be solved on the basis of the principle of reciprocity and equity rather than unilaterally from any side.

• Journal of the korean society of oceanography
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• 제32권3호
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• pp.128-137
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• 1997

This study presents results from a detailed sedimentological investigation of surface sediments obtained from the Korea Strait region, the southern part of the East Sea (Sea of Japan). The distribution of different types of bottom sediments is controlled by the recent fine-grained sediment transport and deposition combined with the lowerings of sea level during the last glacial period, forming a diverse mixture of organic-rich fine-grained and shelly coarse-grained sediments. In comparison to high organic concentration of fine-grained sediments in the inner continental shelf and slope areas, the shell-rich coarse-grained sediments on the outer shelf are discernible being further modified. These coarse-grained sediments are confirmed as relict resulting from the sediment dynamics during the lower sea levels of the last glacial period. Clay mineral distribution of the fine-grained sediments gives information about the transport mechanism. Presence of present-day current system (the Tsushima Warm Current) is most probable source for the fine-grained particles into the open East Sea from the East China Sea, indicating that Holocene sediment dynamics may be used to explain the observed distribution of surface coarse-grained shell-rich sediments.