• Korean Journal of Environmental Biology
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• v.26 no.3
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• pp.145-158
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• 2008

To assess the source of oyster (Crassostrea gigas) and clam (Ruditapes phillippinarum), phytoplankton community structures in the water column and sediment, including the composition of phytoplankton in oyster and clam digestive organs were investigated bimonthly from December 2006 to June 2007 in the Taeahn coastal waters. During the sampling period, water temperature and salinity varied from 7 to 23$^{\circ}C$ and 34 to 35 PSU, respectively. Total phytoplankton abundances at St. O in the water column were higher than those at St. J, whereas total phytoplankton abundances at St. O in the sediment were lower. In addition, total phytoplankton abundances in the water column and sediment were observed to be relatively higher in February and April 2007. Among the diatoms, Paralia sulcata was always dominant, accounting for 41$\sim$87% of total phytoplankton, except St. J for February 2007 during the sampling period. The following phytoplankton compositions observed in the digestive organs of oyster and clam appeared: diatoms such as genus Paralia, Navicula, Melosira and Coscinodiscus, Silicoflagellate Dictyocha, dinoflagellates Prorocentrum and Dinophysis. Phytoplankton compositions observed in the digestive organs of oyster and clam corresponded relatively well with the species composition appeared in the water column and sediments of each season. A significant relationship was found between individual weight of oyster or clam and their digestive organs weight, while there was not a close correlation with total phytoplankton amount. We suggest that P. sulcata always dominated as one of important the food source of oyster and clam in the marine ranching ground of Taeahn coastal waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.243-250
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• 2011

The effects of food, temperature, salinity, and rearing density on the survival and growth of the swimming crab Portunus trituberculatus, were studied. With regard to food, the larval survival rate to zoea IV was the highest (53.9%) in the mixed feed group (rotifers+ Artemia), followed, in order, by the rotifer, commercial feed, and Artemia groups. The growth of young crabs reared on different diets was the highest in group VI. The survival rate to zoea II at 20 to $30^{\circ}C$ ranged between 77.2% and 83.1%, and was the highest for crab I (17.3%) at $25^{\circ}C$. When young crabs were cultured individually at four different temperatures (20, 25, 30, and $35^{\circ}C$), the growth did not differ significantly at 25 to $30^{\circ}C$, but was higher than at $20^{\circ}C$. The survival rate of larvae to crab I was 12.7 and 11.4% at 25 and 28 psu, respectively, while all of the larvae died at 15 psu. For young crabs, there was no significant difference in growth and survival from 20 to 30 psu. The survival rate decreased with increasing rearing density from zoea I to crab I. Each molting cycle took 1 month from crab I to VIII. Subsequently, the interval increased with growth. The mean body weight of crab XV after 24 months was $428.05{\pm}57.63\;g$.

• Ocean and Polar Research
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• v.40 no.3
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• pp.161-167
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• 2018

We examined the effect of salinity and water temperature on hatching and survival rates of fertilized eggs of hybrid grouper (Epinephelus fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) at different developmental stages, determining optimal conditions for their long-distance transportation. Deformities and hatching rates of fertilized grouper eggs were observed at salinities of 24, 27, 30, 33, 36, and 39 psu. The optimal salinity was determined to be 36 psu, with a survival rate of $70.0{\pm}2.0%$. Transportation experiments at 36 psu were conducted at water temperatures of 21, 24, 27, and $30^{\circ}C$, different developmental stages such as morula, 5-myomere, and tail beating for hatching and survival rates. The optimal water temperature and developmental stage for transporatation were $30^{\circ}C$ and tail beating stage and those hatching rates were $50.6{\pm}1.9%$ and $86.3{\pm}1.3%$, respectively. At $21^{\circ}C$, the survival rate by transportation water temperature was highest ($73.1{\pm}10.6%$), but the hatching rate ($17.1{\pm}3.1%$) was lowest. Therefore, the hybrid grouper fertilized eggs (E. fuscoguttatus ♀ ${\times}$ E. lanceolatus ♂) can be most efficiently produced under long-distance transportation conditions during the tail beating stage and at a water temperature of $30^{\circ}C$.

• Fisheries and Aquatic Sciences
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• v.9 no.4
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• pp.160-166
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• 2006

We explored the possibilities of using the freshwater rotifer Brachionus angularis as a live food for small fishes cultured in fresh- or brackish waters. Brachionus angularis were collected from a reservoir for isolation and laboratory culture. Length and width of the lorica were $102.3{\mu}m$ and $76.6{\mu}m$, respectively, and those of amictic eggs were $64.4{\mu}m\;and\;47.9{\mu}m$, respectively. When their growth rates were examined at six different temperatures, i.e., 15, 20, 25, 30, 35, and $40^{\circ}C$, the highest daily growth rate of 0.801 was observed at $35^{\circ}C$, and growth was lower with decreasing temperature. Adaptation to salinity change was evaluated with two different modes of salinity increase: step-wise elevation lasting for short durations of 5 to 30 min or a long duration of 24 h. With the short duration modes, no individuals survived salinity higher than 10 psu, and the number of live individuals did not increase throughout the experiment. However, in the 24-h elevation, the number of individuals increased when salinity was elevated by 1 to 2 psu per day for the first 2 or 3 days, while no increase in number occurred at salinity increments higher than 3 psu per day. In addition, to assess the effect of different diets, four single-component diets (Chlorella vulgaris, Nannochloris sp., baker's yeast, or dry yeast) and three combination diets (C. vulgaris + Nannochloris sp. + baker's yeast + dry yeast; C. vulgaris 70% + baker's yeast 30%; C. vulgaris 30% + baker's yeast 70%) were used. The specific growth rates of B. angularis fed combination diets were higher than those of rotifers fed any single-component diet, with the highest rate of 0.648 in B. angularis fed a mixture of C. vulgaris, Nannochloris sp., baker's yeast, and dry yeast, and the lowest rate of 0.200 in those fed dry yeast only. Our results indicate that the freshwater rotifer B. angularis can be used for seedling production of both freshwater and brackish-water fishes that require small (less than about $120{\mu}m$) live food during their early stages.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.1-6
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• 2012

We studied that the effect of stocking density on growth and survival rate of the scallop, Chlamys farreri (initial shell height 32.97 mm and total weight 5.63 g) from June 2002 to October 2003 in the west coast of Korea. C. farreri is usually the west coast of Korea and northern China in the natural habitat of the coastal species. Range of surface water temperature in the study area was $4.3^{\circ}C$ to $25.3^{\circ}C$, salinity 29.2 psu to 32.1 psu, dissolved oxygen 5.32 mg/L to 7.51 mg/L and pH was 7.84 to 8.12, respectively. The stocking densities were 20, 30, 40 and 50 individuals per a compartment of suspension cage in culture beginning. After 16 months from initiation, ranges of shell height and mean total weight were from 64.35 mm to 76.23 mm and from 41.53 g to 64.85 g. The survival rate was from 82% to 100%. The growth rate of the scallop was negatively correlated with the stocking density. The growth of the shell height and total weight were decreased with decreasing of water temperature. Most of mortality of scallop occurred during March to April and September to October. Survival rate in the stocking density was decreased by density increase and was highest in 20 individual a compartment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.2
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• pp.127-141
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• 1995

The distribution of water mass in Deukryang Bay was investigated using observational data obtained on July 12 (spring tide) and 19 (neap tide) in 1994. In characteristics of water mass at the bay the area is divided into three ones by a vertical attenuation coefficient k and a stratification parameter, log sub (10) (H/U super (3)), was H is depth, and U mean velocity in the bay. The contour of k=0.6 has a similar distribution to the isobath of 10m depth in spring tide, and of 5m depth in neap tide, respectively. This indicates that the water mass in the area between the isobath of 5m and 10m depth is changed by tidal periods. The stratification parameter corresponding to k=0.6 was 2.1~2.2. In the shallow water of 5m depth the characteristics of water mass was distributed in temperature of 25.5~31.$0^{\circ}C$ and salinity of 32.8~33.8PSU(Practical Salinity Unit), the temperature was high and the salinity distributed widely. In the deep water of 10m depth it was the temperature of 22.0~29.5$^{\circ}C$ and the salinity of 33.0~33.6PSU, the temperature was low and the salinity distributed narrowly. In the middle depth water of 5m to 10m depth, the temperature of 22.0~30.$0^{\circ}C$ and the salinity of 32.8~33.5PSU, its values showed the middle between the values of the deep area and the values of the shallow area.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.236-238
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• 2012

본 논문은 저전력 데이터센터에 사용되는 DC 서버를 위한 고효율 DC UPS 결합형 전원분배장치의 구현과 설계에 관한 내용이다. 본 논문이 제안한 노드 준위 UPS 결합형 전원분배장치의 전력효율은 96%에 이르며 저전력 볼륨 서버의 전원공급장치(PSU)와 UPS를 대체할 수 있는 기술이다.

• Atmosphere
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• v.15 no.1
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• pp.1-16
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• 2005

Land-surface and soil processes significantly affect mesoscale local weather systems as well as global/regional climate. In this study, characteristics of land-surface models (LSMs) and soil models (SMs) that are frequently coupled into mesoscale meteorological models are investigated. In addition, detailed analyses on three LSMs, employed by the PSU/NCAR MM5, are provided. Some impacts of LSMs on heavy rainfall prediction are also discussed.

• Journal of the Korean Statistical Society
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• v.12 no.1
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• pp.36-45
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• 1983

After every decennial census in the U.S., national surveys such as the Consumer Expenditures surveys are redesigned. The redesigned samples will be multi-stage systematic samples. Many sampling schemes have been proposed for comparison which requires the estimation and variance estiamtion formula. This paper deals with the surveys redesign research which concerns the sample design within the Primary Sampling Unit (PSU). In constructing the estimators it deals with the problem of which first stage inflation factor to use. The expected value of the proposed estimators is also derived.

• Bulletin of the Korean Mathematical Society
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• v.54 no.6
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• pp.2029-2041
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• 2017

The main aim of this article is to study symmetric (v, k, ${\lambda}$) designs admitting a flag-transitive and point-primitive automorphism group G whose socle is PSU(3, q). We indeed show that such designs must be complete.