• Journal of the Korean Society of Marine Environment & Safety
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• v.11 no.1 s.22
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• pp.77-82
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• 2005

In order to investigate the initial stage of deep water formation between Vladivostok and the subpolar front in the East Sea, the factors, temperature, salinity, dissolved oxygen, measured by multi-ship surveys in ]969 have been used. Deep water formation in the .cast Sea occurs in essentially two different forms: near continent and open ocean formation. The position of eddy derived from potential vorticity matches well with that of deep water formation. The vertical and horizontal distributions of potential vorticity, geostrophic current, temperature, salinity and dissolved oxygen give clues for the preconditioning phase qf open ocean formation like a doming of isotherm, associated with a cyclonic circulation.

• Ocean and Polar Research
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• v.30 no.4
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• pp.373-378
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• 2008

Long-term tide-gauge data from around the Korean Peninsula were reanalyzed. Both the coastal water and the open sea surrounding the Korean Peninsula appeared to have been influenced by global warming. The long-term change in relative sea levels obtained from tidal stations showed a general rising trend, especially near Jeju Island. It is proposed that global warming may have caused shifting of the path of the Kuroshio branch (Tsushima Warm Current) toward Jeju Island, causing a persistent increase in the water levels along the coast of the island over the last few decades.

• Ocean and Polar Research
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• v.28 no.2
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• pp.209-214
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• 2006

The East Sea Branch (ESB) of KORDI will be launched in 2008. She will take a role of monitoring the sea surface topography and temperature by satellites, short- and long-term sea levels by tide gauges, coastal currents and open-sea circulation by setting up coastal radars and mooring current-meters and acoustic equipments, as well as monitoring nearshore processes, coastal erosion and water pollution. A basic program of coastal zone management will help ocean-policy makers to set up right decisions based upon scientific background of the regional data in the East Sea. Networking among the neighboring countries around the sea will supply more useful information not only for experts but also for ordinary vacationers or fishermen. In order for this program to be successfully settled down during the next decade, it is necessary for a leader to have the right vision to attract more experts from global brain pools and to manage the ESB as a leading-edge observatory in the world. Details about this leading-edge operational program are introduced in the text.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.2
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• pp.64-69
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• 2004

The results of analyzing the hydrographic observations in the southwestern sea of Jeju Island in the last 10 days of August 1999 to investigate the characteristics of oceanic front area appeared in the East China Sea in August from is summarized as follows: In Line A, a front appears at Station A5 of 124°E and 31°30'N, showing relatively uniform density of 21.4 to 22.1 in the surface layer of 50m depth, which is distinguished from 22.0 shown in the sides of China and open ocean. In Line B, a front also appears at Station B6 of 124°E and 33°N, of which density is distinguished from 20.0 shown in the sides of China and open ocean as In Line A. As a result, the front area caused by fresh water runoffs from the Yangtze River in the East China Sea is formed at 124°E and 124°30'in the direction of east and northeast from Yangtze River, respectively. Nutrient concentrations in the study area are characterized by higher density in the side of China and by clear density difference between the upper and the lower layers in the side of open ocean, while by uniformly lower density concentration between the upper and the lower layers in the front area. Chlorophyll-α concentrations is high in the sides of China and open ocean, while low in the front area. Judging from the above results, the productivity in the front area is lower according to the inactivity of phytoplankton due to increased flow from vertical mixing between the upper layer and the lower layer. Also, the front area in the East China Sea in summer may be moved towards the adjacent sea of Jeju Island by increasing fresh water runoffs from the Yangtze River in summer.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.285-290
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• 2005

Until now, korean aquaculture industry has been grown largely from a quantitative viewpoint. However, an increase of quantity has caused lots of problems producing a derived effect recently. Nearly 82% of korean aquaculture farms had been installed mainly at inshore of the southern sea and also sewage, factory wastes, high density of fishcage at the limited area and autoinfection have deteriorated inshore fisheries. The offshore have been on the rise for the solution to these problems since it has clear seawater reduces the environmental pollution with much current. As a matter of fact, the existing inshore fishcage facilities have trouble advancing to the offshore due to the rough environmental conditons such as a high sea, strong currents etc.; therefore, it is necessary to develop a new cultivating equipment fit the open sea conditons. In this research, the theoretical study and experimental analysis have been carried out for the fishcage design of the structure which is able to use at the open sea.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.485-490
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• 2017

In this paper, we propose a technique for high speed removal of sea-fog using a graphic processor. This technique uses a host processor(CPU) and several graphics processors(GPU) capable of parallel processing to remove sea-fog from the input image. In the process of removing sea-fog, the dark channel extraction, the maximum brightness channel extraction, and the calculation of the transmission are performed by the host processor, and the process of refining the transmission by applying the bidirectional filter is performed in parallel through the graphic processor. To verify the proposed parallel processing method, three NVIDIA GTX 1070 GPUs were used to construct the verification environment. As a result, it takes about 140ms when implemented with one graphics processor, and 26ms when implemented using OpenMP and multiple GPGPUs. The proposed a parallel processing algorithm based on the graphics processor unit can be used for safe navigation, port control and monitoring system.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.193-201
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• 2014

The sea cage in marine aquaculture might be varied such as on the stability and shape in the open sea by environmental factors. To evaluate the stability of net cage structures in the open sea, the physical and numerical modeling techniques were applied and compared with field observations. This study was carried out to analyse the stability and the volume loss which would have an effect on the fish swimming behavior in the octagonal pillar type fish cage under the open sea. As a results, the volume loss ratio of the fish cage as measured using a depth sensor was indicated a value of the 30.3% under the current velocity (1.1m/s). The fish cage should be consisted of a concrete block with a weight over 10 tons, a mooring rope diameter over 28mm PP, and a shackle of 25mm under the current speed of 1m/sec for reasonable stability.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.2
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• pp.189-197
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• 1997

The vaporizing characteristics of LNG(liquefied natural gas) via heat exchanger with sea water are analytically studied for an open rack vaporizer(ORV). This study is intended to supply the design data for the domestic fabrication of the corrosion-resistant vaporizer tube. A computational program is developed to predict the exit temperature of LNG for various conditions. In the program, thesimple and justifiable heat transfer models are selected for fully-developed internal flow of LNG, the star-shaped finned-tube, and the external falling films of sea water, as well as the possible ice formation and the fouling on the tube walls. It is found that the enongh corrugation inside of the tube wall is the most significant in the vaporizer performance for the current operating conditions. the effects of other design parameters on the heat exchanger between LNG and sea water are quantitatively presented.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.1
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• pp.11-21
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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 pie 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 the induced excess porewater pressure and pressure gradients in the soil, the capacity of open-ended pipe piles installed in a simulated sea depth of greate than 220 m was reduced serevely and the soil plugging resistance was degraded by more than 80% The soil plug was failed because of eh 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 ar open-ended pile in a simulated sea depth of less than 220 m was reduced only by about 10% and the soil plug resistance was degraded by less than 5%.s than 5%.

• Proceedings of the KSRS Conference
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• v.2
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• pp.905-908
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• 2006

The diffuse attenuation coefficient for downwelling irradiance $(K_d({\lambda}))$ is an important parameter for ocean studies. Based on the optical profile data measured during three cruises in the northern South China Sea in autumn from 2003 to 2005, variations in the $K_d({\lambda})spectra$ were analyzed. The variability of $K_d({\lambda})$ shows much distinct features both in magnitude and spectra shape. The $K_d({\lambda})value$ are much higher in costal waters than that of open oceanic waters and the blue-to-green(443/555) ratios of $K_d({\lambda})$ tends to increases with the chlorophyll a concentration ([Chl a]) from open ocean to coastal waters. These characteristics can be explained primarily by the increasing of $a_{w+p}(433)/a_{w+p}(555)$ with [Chl a]. In the short waveband, the relation between $K_d({\lambda})-K_w({\lambda})$ and [Chl a] can be well described by a power law function, suggesting the large contribution of phytoplankton to the variations in $K_d({\lambda})$. As for the spectral model of the diffuse attenuation coefficient, there are good linear relationships between $K_d(490)$ and $K_d({\lambda})$ at other wavelengths, with the slope parameter and the intercept following linear functions within the spectral range $412{\sim}555$ nm. These variabilities of $K_d({\lambda})$ provided much useful information for us to study the bio-optical properties in the northern South China Sea.