• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.461-474
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• 2005

Physicochemical parameters, plankton community structure, and sediment were surveyed from 1988 to 2002, at two months interval, in a eutrophic coastal lagoon (Lake Songji, Korea). The lake basin is separated from the sea by a narrow sand dune, and a shallow sill divides the lake basin into two sub-basins. The stable stratifications and chemoclines are maintained all through the year at 1-2 m depth. DO was often very low (<1 $mgO_2\;{\cdot}\;L^{-1}$) in the monimolimnion. Secchi disc transparency was in the range of 0.5-2.7 m. TP, TN, and Chl. a concentration in the mixolimnion were 0.015-0.396 $mgP\;{\cdot}\;L^{-1}$), 0.223-3.521 $mgN\;{\cdot}\;L^{-1}$, and 0.5-129.8 mg ${\cdot}\;m^{-3}$, respectively. TSI was in the eutrophic range of 54 to 62. Sediment was composed of silt and coarse silt. COD, TP, and TN content of the sediment were 51.4-116.9 $mgO_2\;{\cdot}\;gdw^{-1}$, 0.04-1.46 $mgP\;{\cdot}\;gdw^{-1}$ and, 0.12-1.03 $mgN\;{\cdot}\;gdw^{-1}$, respectively. The 49 phytoplankton species were identified. The maximum phytoplankton abundance obscured the lake in September 2001 (max. density: 23,350 cells ${\cdot}\;mL^{-1}$. The Chlorophyte Schroederia judayi was dominant species in summer (max. density: 20,417 cells ${\cdot}\;mL^{-1}$). The lake showed unique limnological features of a brackish lagoon in respect to biological community, chemical characteristics, and physical phenomena.

• Journal of Aquaculture
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• v.4 no.2
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• pp.111-128
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• 1991

In puan area the environmental surveys were carried out at two farms of hard clam, Meretrix lusoria from April 1987 to November 1978 in order to know heather the farm environments could be rehabilitated for the cultivation of hard clam or not. The range of temperature of surface seawater was $10.7{\~}27.4^{\circ}C$, pH $7.6{\~}8.2$, salinity $22.3{\~}30.3$ ppt, COD $0.20{\~}4.71\;mg/{\ell}$, sulfide $0.04{\~}0.22\;{\mu}g-at./{\ell}$, suspended solid $34.8{\~}199.3\;mg/{\ell}$ chlorophyll a $3.71{\~}49.02\;mg/m^3$, TIN $2.01{\~}24.47\;{\mu}g-a5./{\ell}$, phosphate $0.60{\~}11.03\;{\mu}g-at./{\ell}$ and silicate $4.04{\~}476.36\;{\mu}g-at./{\ell}$. The range of temperature of substratum (bottom soil) was $14.2{\~}29.7^{\circ}C$, pH $8.3{\~}9.5$, water content of substratum was $0.28{\~}0.49\;mg/g$ dried mud, COD $2.80{\~}50.94\;mg/g$ dried mud, total organic matter $1.05{\~}1.97\%$ concentration of total Kjedhal nitrogen $31.9{\~}194.9\;{\mu}g./{\ell}$ dried mud, and sulfide $0.032{\~}0.133\;mg/g$ dried mud. Fine sand was dominant ranging over $92{\~}95\%$ and silt and clay was $2.8{\~}8.1\%$ of the composition of substratum. Some residual agricultural chemicals, ${\alpha},\;{\beta},\;{\gamma}$-BHC, heptachlor, heptachlor-epoxide, aldrin, DDE, DDT and dieldrin were detected in hard clams collected from Puan areas. Especialy, more chemical were detected during the period of rainfalls. From above results, it is considered that the hard clam frams were not yet recovered from deteriorated conditions for aquaculture.

• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.24-32
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• 2000

We investigated the patterns of soil horizon evolution and its water distribution on three different forest stands covered with Larix leptolepis, Pinus koraiensis, and Qercus mongolica on the Experimental Forest of Kyunghee University, located in Kwangju, Kyunggi-Do. Compared to the properties of depths of O and A horizons evolved on the Pinus koraiensis stand, the depths of O and A horizons on the forest stands of Larix leptolepis and Qercus mongolica were shallower, indicating that the soil horizon were deeply influenced by geographical characteristics, its erosive and sedimentary distinction, vegetation cover and its population density. And the bulk densities of the sites selected were lower in the high slope gradient than that in the lower slope gradient at the same depth of soil profile. Therefore, the changes of the soil bulk densities were closely related to the soil organic matter and the vertical transport of soil particle throughout soil depths. On the other hand, the bulk density and organic matter content in soil can influence the water transport phenomena, resulting in decrease of the hydraulic conductivity as the increase in the bulk density, while the organic matter can not affect the hydraulic conductivity on the soil surface layer. For a rainfall infiltration characteristics from a lysimeter experiment established on the stand of Larix leptolepis, the bulk density and slope gradient strongly influenced the vertical transport of water, as well as the lateral movement of rainfall. Conclusively, the characteristics of water movement and distribution in the forest stand can be determined not by the geographical factor such as slope gradient but also by the bulk density and organic matter content remained in soils.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.794-803
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• 1997

Long line suspended culture of oysters has been started commercially in Hansan-Koje Bay since 1969. However, its Annual production has been decreased and culturing periods extended in recent years. So, we investigated environmental parameters and food organisms to identity the causes of poor fatness of oysters in Hansan-Koje Bay from February to November, 1994. As the result, the Water quality of Hansan-Koje Bay was found to be good for culture. For example, the mean concentration of COD was $1.35mg/\ell$, phosphate phosphorus was $0.30{\mu}g-at/\ell$ and dissolved inorganic nitrogen was $4.68{\mu}g-at/\ell$. However, the Hwado island and the inner part of the Hansan-Koje Bay were found to be eutrophicated due to various contaminants transported by land-based activities. But in the central pan of the Hansan-Koje Bay where the oyster farms Have been developed densely, the level of nutrient concentration was very low. During the study period, the dominant species of phytoplankton was Chaetoceros spp. with the percentage of $72.6\%\~87.8\%$ and the mean values of Chlorophyll-a concentration and phytoplankton standing crops were $2.05mg/m^3\;and\;188ind./m\ell$, respectively. The distribution of these parameters also showed similar trends those of nutrients. Especially, chlorophyll-a contents was very low with the concentration of below $0.5mg/m^3$ at central part of the Bay, Juklimpo. The fatness of oysters and the eutrophic index in this area were $18.1\%$ and 0.54, respectively. These values were lower than those of other culturing farms in the southern coastal areas in Korea. Therefore, we estimated that the insufficient food supply due to the low level of nutritional status was the major factors affecting the poor fatness of the Pacific oysters in Hansan-Koje Bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.4
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• pp.360-369
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• 1987

The relationship between the catches of tuna and hydrographic conditions in South-East Pacific region (latitude $5^{\circ}N-12^{\circ}S$, longitude $135^{\circ}W-115^{\circ}W$) was investigated by using the catch data of tuna and Digital Bathythermograph (DBT) data from December 9, 1980 to April 2, 1981. The results are as follows : The study area were located in South Eguatorial Current regions including equatorial upwelling regions in $5^{\circ}N\;to\;12^{\circ}S$. The horizontal mean temperature at the depth of 10m on the first quarter months in the study area was about $25^{\circ}C$C and the salinity of those fishing areas ranged from 34.8 to $35.0\%_{\circ}$. Yellowfin tuna and bigeye tuna were mainly caught in SW vertical temperature profile type, which the depth of thermocline ranged from loom to 300m, and temperature difference of thermocline was about $12^{\circ}C$. The deeper the depth of thermocline, the more the catches of tuna. While albacore tuna was caught well in SS vertical temperature profile type which the temperature of thermocline ranged from $9^{\circ}\;to\;26^{\circ}C$ and its gradient was very smooth. The depth of 1 ml/l surface of dissoved oxygen content ranged from loom to 200m in the South-East Pacific between longitude $140^{\circ}W-100^{\circ}W$, but it was shallower than 100 m near the North-South American continent. The catches of bigeye tuna were larger than those of yellowfin tuna in South Equatorial Current region. As approaching to the South and North American continent, the catches of yellowfin tuna and bigeye tuna decreased because the thermocline becomes shallower and steeper and the depth of the 1 m1/1 surface of dissolved oxygen content became shallower.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.27-36
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• 2000

We investigated the phytoplankton community from June to September 1997 in the waters off Kohung, Korea where red tides dominated by harmful dinoflagellates had occurred from August to September or October since 1995. We took water samples five times from 5 depths at 6 or less stations in this study period. The most dominant harmful dinoflagellate during the red tide which had outbroken on August 24, 1997 was Gyrodinium impudicum, not Cochlodinium polykrikoides. On August 21 just before the harmful red tide occurred the abundance of G. impudicum at the inner bay station, 90cells $ml^{-1}$, was higher than that at the outer bay station. However, on August 27 just after the red tide had outbroken, the abundance of G. impudicum at the inner bay station did not increase, whereas that at the outer bay increased rapidly and reached to the maximum of 30,000 cells $ml^{-1}$. Instead, diatoms such as Skeleltonema costatum, Chaetoceros pseudocurvisetus, Pseudonitzschia pungens rapidly increased at the inner bay station where fresh water from lands has reached. The high abundance of diatoms might have inhibited the growth of red tide dinoflagellates at this station. The transport of already formed red tide patches from offshore areas, aggregation of scattered cells driven by physical forces, and/or competition between diatom and dinoflagellates might be responsible for this appearance of dense red tide patches at the outer bay station.

• Journal of Plant Biotechnology
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• v.43 no.3
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• pp.261-271
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• 2016

Citrus is an economically important fruit crop widely growing worldwide. However, citrus production largely depends on natural hybrid selection and bud sport mutation. Unique botanical features including long juvenility, polyembryony, and QTL that controls major agronomic traits can hinder the development of superior variety by conventional breeding. Diverse factors including drastic changes of citrus production environment due to global warming and changes in market trends require systematic molecular breeding program for early selection of elite candidates with target traits, sustainable production of high quality fruits, cultivar diversification, and cost-effective breeding. Since the construction of the first genetic linkage map using isozymes, citrus scientists have constructed linkage maps using various DNA-based markers and developed molecular markers related to biotic and abiotic stresses, polyembryony, fruit coloration, seedlessness, male sterility, acidless, morphology, fruit quality, seed number, yield, early fruit setting traits, and QTL mapping on genetic maps. Genes closely related to CTV resistance and flesh color have been cloned. SSR markers for identifying zygotic and nucellar individuals will contribute to cost-effective breeding. The two high quality citrus reference genomes recently released are being efficiently used for genomics-based molecular breeding such as construction of reference linkage/physical maps and comparative genome mapping. In the near future, the development of DNA molecular markers tightly linked to various agronomic traits and the cloning of useful and/or variant genes will be accelerated through comparative genome analysis using citrus core collection and genome-wide approaches such as genotyping-by-sequencing and genome wide association study.

• Childhood Kidney Diseases
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• v.4 no.2
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• pp.127-135
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• 2000

Purpose: Cyclosporine(CsA) is a potent immunosuppressant but the use of CsA is associated with various side effects, especially nephrotoxicity. In tile kidney, salt depletion activates tile renin-angiotensin-aldosteron(RAS) system and accentuates chronic CsA nephropathy. We postulate that angiotensin converting enzyme inhibitors(ACEI) can prevent chronic CsA nephropathy, since ACEI may inhibit this cascades. This study was aimed to assess the effect of ACEI on chronic cyclosporin nephropathy in salt depleted rats. Methods: 36 Fischer-344 rats were divided into 6 goups. Group I received normal salt diet(NSD). Group II received a low salt diet(LSD). Group III received CsA with a NSD. Group IV received CsA with a LSD. Group V received NSD+CsA with ACEI. Group VI received LSD+CsA with ACEI. Rats were sacrificed after six weeks and the glomerular filtration rate(GFR), serum sodium, potassium and whole blood cyclosporine levels were measured. Renal tissues me sampled for the observation of histological changes. Results: No differences in blood CsA level & serum sodium were found between groups during the course of this experiment. Serum potassium in group VI was significantly increased compared with group IV and V (P<0.05). In groups treated with CsA only and in those where CsA was combined with ACEI, GFR was found to be significantly more decreased in LSD than NSD, and GFR in group V was significantly decreased in comparison with group III (P<0.05). Renal histologic lesions associated with CsA which consisted of cortical interstitial fibrosis, tubular atrophy and hyalinization of arterioles were more severe in tile LSD group. But, no differences were observed between tile groups treated with CsA and ACEI, and the groups treated with only CsA. Conclusion: Salt depletion associated with the activation of the RAS system accentuated chronic CsA nephrotoxicity, but, ACEI could not reduce the functional and morphological changes of salt depleted kidneys, in which nephropathy can be exacerbated in spite of the blocking of the angiotensin II pathway. further studies are required to elucidate whether Am ameliorated the effect of salt-depleted CsA nephrotoxicity upon the effective renal blood flow.

• Journal of Life Science
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• v.15 no.2 s.69
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• pp.225-230
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• 2005

The aim of this study was to examine the fluctuation in phytoplankton assemblages with regarding to environmental conditions and nutrients, which were surveyed quarterly over the fours seasons (February, May, July, and October). In turn, an understanding of biological effects should provide insights into a wide range of initiated Cochlodinium blooms in Narodo. Sampling was carried out throughout 2001 on the coasts of Busan (St. 1), Yeosu (St. 2), Narodo (St. 3), Kohung (St. 4), and Kwangdo (St. 5). The maximum surface water temperature was recorded in July, and it ranged from 20 to $22^{\circ}C$. Salinity showed no great variation, which maintained itself in the range of 29-34 psu. The maximum surface salinity was recorded in February, which was about 34 psu. The chlorophyll $\alpha$ concentration of the surface water ranged from 0.01 to $1.3\;{\mu}g\;1^{-1}$. The concentrations of $NH_{4}-N $ were persistently high from February to October; in particular, the peak was observed at St. 1 in February and May (0.15 and $0.19\;{\mu}mol\;1^{-1}$, respectively), while it was detected at St. 2 in July and October (0.22 and $2.2\;{\mu}mol\;1^{-1}$ respectively). Similar trends to those for $NH_4-N $ were observed in the concentrations of $NO_{2}-N$ and $NO_{3}-N$. In contrast to nitrogen, a distinct peak of $NO_{4}-P$ at St. 3, 4, and 5 was observed throughout year $(0.01-0.1\;{\mu}mol\;1^{-1}$ except for October. At St. 1 encounter a peak of cell number of 30,000 and $13{\times}10^3$ cells $1^{-1}$, respectively, in July and October. During the period of this study, the majority of the taxa were diatoms. The dinoflagellates were rather abundant after February, in particular at St. 3, 4, and 5 which attained an abundance of $10\~20\%$without marked fluctuation during the period of this study. At St. 3, the highest average cell width, $178.11\;{\mu}m$, was recorded: the highest cell length, $337.72\;{\mu}m$, was measured in July. Consequently, dinoflagellates bloom in July at Narodo influenced by warm water current are not only associated with a desirable development of cell morphometric characteristics, but also with the health growth of C. polykrikoides. During the period of this study, warm water currents caused an increased water temperature in Narodo, but did not change the amount of nutrients.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.119-130
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• 2000

Mn, Zn, Cd and Pb in shells of Littorina brevicula, which lives ubiquitously in intertidal zone around the Korean coast, were analyzed to determine the relationship between metal levels in its shell, ambient seawater and its tissue. Periwinkles and seawater samples were collected from 38 sites along the Korean coast in January 1997. Mn contents in shells of this organism show the range of 7.0 ${\mu}g$/g-211 ${\mu}g$/g (mean 59 ${\mu}g$/g) and are the lowest in northern east coast but high in western south and west coast. Close relationship between Mn contents in shells and metal levels both in seawater and in tissues indicates that Mn in shell might be incorporated from ambient seawater by a biological process. Although the contents of Cd in shells did not reflect the distribution of total Cd in seawaters and they were very low compared to those in tissues, they followed spatial gradient of contents in tissues. However, the spatial distribution of Zn contents in shells accords neither ambient seawater nor tissues, while it is negatively correlated with the contents of Na in shells. This fact suggests that Zn contents might be controlled by salinity of ambient seawater. On the contrary, Zn contents in highly polluted sites near Onsan Bay show generally higher levels than other sites. The contents of Pb show the range of 0.1 ${\mu}g$/g-17.5 ${\mu}g$/g (mean 1.01 ${\mu}g$/g) and the highest in sites near Onsan Bay. Although the spatial distribution of shell Pb does not follow those of tissue, Pb in shells of Littorina brevicula may be controlled both by shell secretion process and by Pb levels in ambient seawater because the contents of Pb in the shell decrease steadily with growth and vary with levels of Pb in ambient seawater.