• The Korean Journal of Malacology
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• v.29 no.3
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• pp.197-205
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• 2013

Even though seedling production of Haliotis discus hannai has fully developed, the culture of benthic diatom as a live food for larvae is still a barrier to solve in commercial hatchery. The farmer depends on mixed microalgae which are non-selectively attached on the plate by flowing of natural seawater. The adequate diatom on the plate for the larvae in terms of quality and quantity is always significant bottleneck in the hatchery. In this study, two benthic diatom species, Caloneis schroederi and Rhaphoneis sp. were separately cultured in mass and inoculated to four tons' settlement tank of the larvae. And the larvae and the spats were cultured for nineteen and nine weeks, respectively. The result on seedling production of H. discus hannai with this method was compared to that of the farmer's traditional method as a control. With regard to variation of species composition of benthic diatom on the plate, C. schroederi and Rhaphoneis sp. were dominant for first three weeks after inoculation. But the diverse diatoms mainly, Navicula, Amphora, Cylindrotheca, Licmophora, Pleurosigma began to attache on the plate from the 4th week. The larvae attached 2.5 times more in C. schroederi tank than in the control tank. The final total biomass of the seeds in Rhaphoneis sp. tank was 3.2 times more than that of the control tank. The retared-spats in the seedling production also showed significantly higher growth and survival in the spat fed Rhaphoneis sp. or C. schroederi than those in the control group. We suggest that C. schroederi is proper for settlement of the larvae and Rhaphoneis sp. is appropriate for the growth of the larvae and spats in the commercial hatchery of H. discus hannai.

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.177-180
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• 2008

Based on Latti(1974) and Jacobs&Way(1968)'s theory, we estimate the coastal area of Jeju and Busan cities. According to the estimateio, The seawater pumping line causes the problem of coastal landscape. Water management treatment of coastal region has been an important problem in Jeju city and Busan city since the distributions of pipeline if the pumping system made a bad view in coastal region. To solve the problem, we observed the pipelines that are on the surface around the coastal region we proposed two methods, that is, one is a short time treatment, the other is a long time one. The short is based on the colour treatment, which is pipeline colour changing into surround natural one. The long time is the construction plan design method. Although the later method was very useful in Jeju island. However, it takes a lot of time and money. Therefore, in the situation, the short time is the better than the long time one.

• Korean Journal of Environmental Biology
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• v.39 no.1
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• pp.81-87
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• 2021

The monthly variability in marine algal flora and community structure was examined in the intertidal zones of Doripo, and the biomass of an edible alga, Ulva prolifera, at Gaip-ri of Hampyong Bay on the southwestern coast of Korea was investigated over one year from April 2008 to March 2009. A total of 22 seaweeds were identified including five green, four brown, and 13 red algae. Based on importance value, Ulva australis was dominant over the year and the subdominant species were Ulva linza and Caulacanthus ustulatus at the Doripo coast of Hampyong Bay. The vertical distribution in terms of importance values was in the order of Ulva linza - C. ustulatus - U. australis - Sargassum thunbergii from the upper to the lower intertidal zones. The biomass of U. prolifera ranged between 2.4-98.2 g dry wt. m^-2, with a maximum in June and a minimal in November. In the field, U. prolifera biomass could be positively related to seawater temperature. However, further research on the association between biomass and other environmental factors such as nutrients and light intensity is required.

• ALGAE
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• v.36 no.4
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• pp.231-240
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• 2021

Saccharina sculpera is highly valued for human consumption and value-added products. However, natural resources of this kelp have decreased sharply and it is in danger of extinction. Resources recovery through cultivation is being trialed to enable the sustainable use of this species. In this study, the temperature range for survival and optimal growth of juvenile S. sculpera was identified and applied to field cultivation. This study investigated the survival and growth of juvenile S. sculpera under six temperatures (i.e., 5, 10, 15, 16, 18, and 20℃) and two light intensities (i.e., 20 and 40 µmol photons m^-2 s^-1) in an indoor culture experiment. In these experiments, the blade length decreased at 16℃ under the both light intensities. The thalli died at 20℃ and 20 µmol photons m^-2 s^-1, and at 18-20℃ and 40 µmol photons m^-2 s^-1. During the field cultivation, early growth of S. sculpera was highest at the 5 m depth and growth decreased as the water depth increased. When the initial rearing depth was maintained without adjustment throughout the cultivation period (from December to October), all the cultivated S. sculpera plants died during August and September. However, S. sculpera plants lowered from 5 to 15 m and grew to 90.8 ± 13.1 cm in July. The seawater temperature at 15 m depth was similar to the upper level of thermal tolerance demonstrated by juvenile S. sculpera in the indoor culture experiments (16℃ or lower). The plants were subsequently lowered to 25 m depth in August, which eventually led to their maturation in October. The present study confirmed that improved growth rates and a delay in biomass loss can be achieved by adjusting the depth at which the seaweeds are grown during the cultivation period. These results will contribute to the establishment of sustainable cultivation systems for S. sculpera.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.1
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• pp.149-157
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• 2019

This study interested on management of broodstock and the effect of raise the temperature for promotion of maturity in Tresus keenae. For management of broodstock, we performed indoor and outdoor culture. In addition, broodstock was put in exposure and immersion condition. This experimental design is aimed at knowing the optimal management of broodstock. In addition, we investigated the promotion of maturity, growth and survival rate when raise the temperature of the breeding seawater of broodstock in winter season. Result that, the management of broodstock was shown to be more effective obesity and survival rate in outdoor culture than indoor culture. In addition, there is no anthropogenic food supply in management and it is easy to management because it is kept under natural environmental conditions. Therefore, It is considered appropriate to management to outdoor culture. In raise the temperature, survival rate was lower in the experimental group than in the control group. However, obesity was significantly increased compared with the control group. Also, gonad showed that the sex maturity was promoted. If sex maturation is not developed due to seasonal water temperature, the promotion of sexual maturity through heating is considered to be an effective method in terms of artificial seed production.

• Korean Journal of Environmental Biology
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• v.35 no.3
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• pp.380-388
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• 2017

Factors affecting spatial distribution of halophytes were analyzed in June 2012 at the Goraebul coastal dunes. In the Goraebul sand dune, distribution of halophytes was divided into three groups. The first group belonging to Elymus mollis, Carex kobomugi, Calystegia soldanella, Ixeris repens and Glehnia littoralis was distributed in the ridge of primary sand dune and dune slack. The second group belonging to Lathyrus japonicus and Zoysia macrostachya was distributed in the dune slack. The third group belonging to Pinus thunbergii, Vitex rotundifolia and Linaria japonicus was distributed in the pine forest of the secondary sand dune. E. mollis, C. kobomugi, C. soldanella, I. repens and G. littoralis was distributed in relatively unstable habitat of sand dunes due to the large amount of sand movement. V. rotundifolia was distributed in a relatively stable habitat. Factors that have the greatest influence on distribution of halophytes in the Goraebul sand dunes are distance from the seashore, topography, and the pine forest. The Goraebul sand dune is a relatively well-preserved area with minimal human intervention. Therefore, different distribution of physico-chemical factors by natural processes is essential to spatial distribution of halophytes than other sand dunes in Korea. Significant natural processes in the Goraebul sand dunes were advance and retreat of coastlines from waves, erosion and sedimentation of sand due to wind and waves, and dispersal of seawater.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.17 no.3
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• pp.181-188
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• 2012

Despite the ecological importance of seagrass beds, their distributional information in Korean coastal waters is insufficient. Therefore, we used hydroacoustic system to collect accurate bathymetry and classification of seagrass, and Kompsat-2 (4 m spatial resolution) image for detection of seagrass beds at Deukryang Bay, Korea. The accuracy of Kompsat-2 image classification was evaluated using hydracoustic survey result using error matrix and Kappa value. The total area of seagrass beds from satellite image classification was underestimated compared to the hydroacoustic survey, estimated 3.9 and $4.5km^2$ from satellite image and hydroacoustic data, respectively. Nonetheless, the accuracy of Kompsat-2 image classification over hydroacoustic-based method showing 90% (Kappa=0.85) for the three class maps (seagrass, unvegetated seawater and aquaculture). The agreement between the satellite image classification and the hydroacoustic result was 77.1% (the seagrass presence/absence map). From our result of satellite image classification, Kompsat-2 image is suitable for mapping seagrass beds with high accuracy and non-destructive method. For more accurate information, more researches with a variety of high-resolution satellite image will be preceded.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.117-128
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• 2010

The water qualities of Namdae-stream, Yeongok-stream and Sacheon-stream were examined, by using physicochemical factors, trophic status and epilithic diatoms from May 2008 to February 2009. The physicochemical water qualities of three streams were, except for some construction areas and sites of downstream, generally good, having less concentration than BOD of $2\;mg\;L^{-1}$. As for the sites of downstream, there were ongoing pollution such as graduation of nutrients in Namdae-stream and Sacheon-stream, due to salinity of seawater and topographical feature of the closed estuary. The examination of trophic status of Namdae-stream showed mesotrophic status in all the sites. Also, eutrophication was in progress as from the upstream to the downstream of Yeongok-stream, and Sacheon-stream showed eutrophic status in all its sites. As a result of the biological water quality assessment, Namdae-stream, excluding the downstream site, came out to be $\beta\sim\alpha$-oligosaprobic, and biological water quality was good, having TDI less than 50. Some construction sites and downstream site of Namdae-stream are $\beta$-mesosaprobic, and with the TDI over 70, the biological water quality assessment came out to be polluted. Yeongok-stream is $\beta\sim\alpha$-oligosaprobic, and its biological water quality is good, having TDI less than 40. Sacheon-stream, excluding the upstream site on May 2008 and February 2009, is $\beta\sim\alpha$-mesosaprobic, and its TDI over 70 shows that it has been polluted. The correlation analysis showed a high correlation in both DAlpo and TDI. Also, biological assessment of water quality (DAIpo, TDI) showed higher correlation with TSI rather than BOD.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.408-412
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• 2000

The juvenile Bobiids, Faronirobius gymnauchen, were reared for 40 days under $0{\~}33.6{\%_{\circ}}$ salinity conditions to examine the effects of various salinity on its survival, growth and oxygen consumption rates, Survival rate was significantly declined below $6.7{\%_{\circ}}$ salinity, and daily growth rate was also reduced below $10.1{\%{\circ}}$. Body length and weight of gobiids reared below $10.1{\%_{\circ}}$ were smaller than those of gobiids reared above $20.2{\%_{\circ}}$. Oxygen consumption rate in the salinity conditions ${\leq}13.4{\%_{\circ}}$ was significantly reduced with decreasing salinity than that in natural seawater ($33.6{\%_{\circ}}$), This study revealed that low salinity reduced survival, growth and oxygen consumption rates of the juvenile gobiids suggesting potential influence on the natural mortality of F gymnauchen in the coastal areas.

• The Korean Journal of Petroleum Geology
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• v.3 no.1 s.4
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• pp.28-39
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• 1995

The objective of this study is to investigate the origin of the dolomite in the Pungchon Formation of the Choseon Supergroup near Taebaeg City, Kangwondo, Korea. The Pungchon Formation is composed of limestone, dolomitic limestone, and dolomite with thin beds of flat pebble conglomerate (FPC) and mudrock. Texturally, the dolomite in the Pungchon Formation can be divided into four types; 1) coarse-sized, xenotopic dolomite in massive dolomite, 2) medium-siEed, idiotopic dolomite in flat pebble conglomerate, 3) xenotopic dolomite replacing ooids, algalnodules, and echinoderms, and 4) the dolomite in mottled fabric. The dolomite in mottled fabric can be subdivided into three types; a) coarse-sized, xenotopic saddle dolomite cement, b) medium-sized, idiotopic, cloudy-centered, clear-rimmed (CCCR) dolomite, and c) coarse-sized, idiotopic dolomite. The carbon isotopic composition of the Pungchon dolomite is in the range of $-2.8-1.4\%_{\circ}(PBD)$, suggesting that the carbon isotopic composition was buffered by the preexisting marine carbonates. Lighter oxygen isotopic values ($\delta^{18}O-15.7-8.7\%_{\circ}, PBD$) indicate that the Pungchon dolomite may have formed under high temperature in a burial diagenetic environment. The higher initial $^{87}Sr/^{86}Sr$ ratio of the Pungchon dolomite (0.7010-0.7161) than that of the coeval Cambrian seawater (0.7088-0.7092) indicates that dolomitizing fluids had been modified from the isotopic exchange with continental crust. Low Sr and Na contents(<200 ppm) of dolomite agree well with previously reported data for burial dolomite. Hifh Fe and Mn contents of the dolomite support the idea that the Pungchon dolomite may have formed in a deep burial diagenetic environment.