• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.4
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• pp.309-314
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• 2013

Temporal and spatial variations and species composition of ichthyoplanktons were investigated by Bongo net in a sea area with the construction of artificial upwelling structure at 13, June, 21 September, and 23 September in 2012. A total of fish eggs was 4,849 ind./$1,000m^3$, and fish larvaes was 641 ind./$1,000m^3$ in the study area. The common fish eggs was Engraulis japonicus which was composed of 57.5%, and unidentified I, II, III and IV were occurred with decreased number of individuals order. For fish larvaes, Pictiblennius yatabei, Repomucenus sp.A, sp.B and Scomber japonicus were dominated, however, other species were Engraulis japonicus, Konosirus puntatus, and unidentified I, II. Temporal variations of fish eggs and larvae were remarkable differed. Higher numbers of fish eggs and larvaes were July 2012, whereas those were lower at August 2012. Spatial variations of those were also significantly differed with higher numbers were at station 2 and 3 during study periods. The total number of fish eggs and larvae was about 4 fold against numbers of those in the compared area far from study area. These results indicated that higher numbers of fish eggs and larvaes were due to influx much more nutrients and food organisms with artificial upwelling.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.270-273
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• 2002

천연적인 용승현상이 발생하는 지역은 청결하고 풍부한 염양염류와 낮은 수온을 가진 심층수에 의해 좋은 어장을 형성한다. 그러므로, 전체 해양면적의 0.1%에 해당하는 천연용승 발생 지역에서 어획량은 전체의 거의 절반을 차지한다. 이러한 심충수를 인공적으로 끌어올리기 위해 파랑에너지를 이용하는 인공용승장치 에 관한 연구가 최근에 시도되고 있다. (중략)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.207-217
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• 2008

Costal regions in Korea often suffer severe damages due to wave-induced disasters, storm surge disasters and so on. therefore, many engineers and researchers have devoted their energy to prevent these costal disasters. The development of artificial reefs including sunken vessels is one of their remarkable achievements and various kind of these artificial upwelling structures have been designed and applied. However, the flow characteristics around a Tetrapod under the water has not been investigated experimentally. So in this article, in uniform flow of circulating water channel and some different velocities, PIV measurement has been conducted on the flow characteristics behind a Tetrapod. The results were analyzed on the flow characteristics of both cases of a Tetrapod. Therefore, it can be concluded that the both cases have its own distinctive flow characteristics behind the bluff body; Case A has an steep upstream flow pattern. On the contrary, Case B has an developed downstream flow pattern in the near wake of the Tetrapod. The velocity gradient at position x=150mm of Case-A appears gently up and down But, the velocity gradient at the same position of Case-B appears better highly up and down.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.155-158
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• 2006

한국 남해안 거제도 앞바다에 투하된 인공용승구조물에 대한 유통 변화를 파악하기 위해 ADCP(Acoustic Doppler Current Profiler)를 선박에 장착하여 정선관측을 실시하였다. 관측결과 구조물 투하전과 후의 유통비교를 보면 구조물 주변역에서 표층에서부터 수심 $30\sim40m$까지의 충과 그 이심까지의 흐름이 다르게 나타났다. 또한 구조물 주변역에서 연직유동성분의 흐름이 구조물 투하 전에는 하강류의 분포가 많이 나타났으나 구조물 투하 후에는 상승류의 성분이 많이 나타남을 알 수 있었다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.233-233
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• 2011

This study describes the characteristics of accretion and scour around artificial reefs in Korea. The survey for accretion and scour was made at a dice reef set consisting of 137 dice reefs. The volume of a dice reef unit is 8 $m^3$. The reef set was placed on the muddy sand at 21.6 m in November of 1999. Equipment used in the survey includes Side Scan Sonar, Multi Beam Echo Sounder, Sub-Bottom Profiler and water current meter. According to the results, the artificial reefs are heaped up at two to three times (4 m) the height of the dice reef. The maximum current around the artificial reefs was 81.5 cm/sec at the ebb tide and 72.7 cm/sec at the flood tide. Scour around artificial reefs occurs upstream to the flow while accretion is formed at wake zone in the downstream. The height of accretion ranges from 2.4 to 3.0 m. The crest of the accretion is formed at the distance of about 10 m from the edge of the reef. The slope of accretion is formed steeply at the vicinity of the reef which is at right angles to the direction of main current, and grows gently lower with the increased distance from the reef. Scour is continuously caused by upwelling from the reef set and by side currents that flow parallel to side of the accretion. Also, scour takes place on the deposited sediment rather than on the remaining bottom sediments. This means that, once fully formed, the depth of scour gully on both sides to the direction of main current hardly changes.

• Journal of Aquaculture
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• v.10 no.3
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• pp.373-380
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• 1997

The experiments were conducted to improve the mass production of Nile tilapia, Oreochromis niloticus, seed in closed recirculation systems. It was observed that smaller females (340g av. body weight) under lower stocking density (1.2 kg/$m^2$)) group produced 3.6 times more fry than larger females (612g av. body weight) under higher stocking density (2.1kg/$m^2$) group when the fry were collected at 30 days after the broods stocked. The clutch removal method where the eggs and sacfry were collected from female mouth followed by artificial incubation showed improved seed production, when compared to the traditional natural mouth-brooding method by harvesting free swimming fry from brood tanks (P<0.05). Under the clutch removal method, short-term incubatin of brooders (14 days) was proven to be more effective than long-term incubatin (21 days). Hatching success of clutch removed eggs was ranged from 55.7 to 91.5% in 1.8$\ell$ of upwelling incubators depending on the different development stages.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.202-211
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• 2010

The variations of physico-chemical factors and the species compositions of phytoplanktons were investigated to analyze the marine ecosystem at the depths during summer in the coast of Dokdo (stations DOK 1-3). The mean values of conductivity (48.9 mS $cm^{-1}$), salinity (32.9 psu) and total suspended solids (57.9 mg $L^{-1}$) were the highest in DOK 1. The biomass (Chl-a) of phytoplanktons was the highest in the surface of DOK 1 (2.61 ${\mu}gL^{-1}$). By the means of physicochemical factors (salinity, turbidity, Chl-a, TN, TP and Si), the water estimated in the coast of Dokdo was more eutrophicated than that in 2008. The phytoplanktons were a total of 42 species in Dokdo, which were composed of 33 species (78.6%) for Bacillariophyceae and 9 species (21.4%) for Dinophyceae. The standing crops of phytoplanktons were the highest ($18{\times}10^3$ cells $L^{-1}$) in the surface of DOK 2 and in the surface of DOK 3, while they were the lowest ($2{\times}10^3$ cells $L^{-1}$) at depth of 40 m of DOK1 and at depth of 30 m of DOK 3. The dominant species of phytoplanktons were Chaetoceros castracanei ($6{\times}10^3$ cells $L^{-1}$) in the surface, Rhizosolenia alata f. gracillima ($3{\times}10^3$ cells $L^{-1}$) at depth of 20 m and Protocentrum compressum ($4{\times}10^3$ cells $L^{-1}$) at the depth of 30 m of DOK 1. At the surface of DOK 2, the dominant species was Bacillaria paxillifer ($6{\times}10^3$ cells $L^{-1}$), while it was Hemiaulus indicus ($12{\times}10^3$ cells $L^{-1}$) at the surface of DOK 3. The DOK 1, which is affected by upwelling, whirlpool and circulation due to the East Korean Warm Current, was the most eutrophicated water body among three stations. The monitoring of marine ecosystem in the coast of Dokdo should be continued to propose the alternatives for water quality and species conservation and to purify the eutrophicated water body due to artificial pollutants as well as natural effectors by the global warming, the climatic change, etc.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.565-572
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• 2004

Residual current plays more important role than the tidal current for long-term material transport in coastal areas. The main component of residual current is tide-induced residual current. Otherwise, wind driven current and buoyancy-driven current are important components which change the residual current. To clarify the characteristic of coastal current, application of a three -dimensional model is necessary. This study focuses on clarifying the stratified systems of coastal water affected by freshwater runoff from a river and analyzes the structure of current at Ulsan bay by applying a three-dimensional buoyancy-driven current model. According to the result of “Ulsan bay” study, it shows that the surface layer in semi-enclosed estuaries, which affected by freshwater runoff. has flows going out, and the bottom layer has flows coming in. Besides when the wind blows toward inside of the bay, the surface layer has flows coming in and the bottom layer has flows going out as compensation flows for the surface circulation. The results of simulation could be applicable to examine vertical upwelling, which might be caused by construction of artificial fishing reef to build aqua farm, submerged breakwater to control coastal sediment, and the formulation of oceanic ridge, or a basic study on application to the usage of deep water.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.118-125
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• 2012

World population has increased rapidly following the industrial revolution, reaching 7 billion in 2012. Several forecasts estimate that this number will rise to about 8 billion in 2025. Improvements of living standards in developing nations have also raised resource and energy demands worldwide. In consequences, human beings have faced many global and urgent problems, such as global warming, water and food shortages, resource and energy crises, and so on. Many ocean utilization technologies for avoiding or reducing such big problems have been developed, for examples $CO_2$ ocean sequestration, seawater desalination, artificial upwelling, deepwater mining, and ocean energies. It is important, however, to assess such technologies from the viewpoints of sustainability and public acceptancy, since the aims of those technologies are to develop sustainable social systems rather than conventional ones based on fossil resources. Inclusive Marine Pressure Assessment and Classification Technology Research Committee (generally called IMPACT Research Committee) of Japan Society of Naval Architects and Ocean Engineers, has proposed Inclusive Impact Index "Triple I" as an indicator, which can predict both environmental sustainability and economical feasibility, in order to assess the ocean utilization technologies from the viewpoints of sustainability and public acceptancy. This index was considered by combining Ecological Footprint and Environmental Risk Assessment. The Ecological Footprint and the Environmental Risk Assessment are introduced in the first part of this paper. Then the concept and the structure of the Triple I are explained in the second part of this paper. Finally, the economy-ecology conversion factor in Triple I accounting is considered.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.48-57
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• 2009

The characteristics of physico-chemical factors and the species compositions of phytoplankton were investigated to analyze the marine ecosystem at the depths during summer in the coast of Dokdo (stations DOK1$\sim$3). The mean values of conductivity (32 mS cm$^{-1}$), total dissolved solids (45 mg L$^{-1}$), salinity (35.5 psu), total suspended solids (39 mg L$^{-1}$) were the highest in DOK1. The biomass (chl-${\alpha}$) of phytoplankton was the highest in the surface of station DOK1 (3.1 ${\mu}g$ L$^{-1}$). By means of physico-chemical factors (salinity, turbidity, chl-${\alpha}$, T-N, T-P and Si), the coast of Dokdo was estimated to be more polluted than the previous results in 2000. A total of 72 species in Dokdo were composed of 54 species (76.1%) for Bacillariophyceae and 13 species (18.3%) for Dinophyceae, 3 species (4.2%) for Chrysophyceae and 1 species (1.4%) for Cyanophyceae. The standing crops of phytoplankton were the highest (8.5 $\times$ 10$^4$ cells L$^{-1}$) at 20 m of station DOK1, while they were the lowest (1.65 $\times$ 10$^4$ cells L$^{-1}$) at 30 m of station 1. The dominance index was maximum (0.73) at 10 m of station DOK1 and was minimum (0.4) at 30 m of station 1. The diversity index was the highest (2.92) in the surface of station 2, while it was the lowest at 20 m (1.58). The dominant species of phytoplankton were Chaetoceros affinis (3.3 $\times$ 10$^4$ cells L$^{-1}$) at 20 m, Climacosphenia moniligera (2.8 $\times$ 10$^4$ cells L$^{-1}$) at 40 m and Melosira juergensii (1.7 $\times$ 10$^4$ cells L$^{-1}$) at 10 m of station DOK1. At the surface of station DOK2, the dominant species were Bacillaria paxillifer and Richelia intracellularis (1.4 $\times$ 10$^4$ cells L$^{-1}$, respectively), while it was Paralia sulcata (1.6 $\times$ 10$^4$ cells L$^{-1}$) at the surface of station DOK3. The station DOKl, where affected by upwelling, turbulence and convection due to the East Korean Warm Current, was the most eutrophicated water body in three stations. The monitoring of marine ecosystem in the coast of Dokdo should be continued to show the alternatives for water and species conservation and to purify the eutrophicated water body due to artificial pollutants as well as physico-chemical factors by the global warming, the climatic change, CO$_2$ etc.