• The Korean Journal of Malacology
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• v.24 no.2
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• pp.153-159
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• 2008

We investigated artificial mass seed production of a Chinese scallop, Patinopecten yessoensis, in 2004. The GSI(gonad somatic index) of the Chinese scallop, P yessoensis was 17.2 on mid-February, 20.2 on mid-March, while that of Korean scallop, P yessoensis was 6.9 on mid-February, 10.8 on mid-March. Matured 120 females and 350 males were selected for artificial mass production. They were exposed in air for 1 hr at over $20^{\circ}C$, and placed into a spawning tank(20 ton) containing sea water treated with UV radiation at $12^{\circ}C$. We gained a total of 228,000 thousand scallop embryos between March 10th and 15th, and reared larvae at the indoor tank during 25 days. When the mean shell length of larvae reached 250 ${\mu}m$ and they have eye-spots, the number of pre-settling larvae was 47,500 thousand. We gained 1,850 thousand attached scallop spats from two kinds of collectors. Attached spats were reared in indoor tank for different periods from 5 days to 60 days. They were divided into 5 groups according to the length of reared days. Each group of attached spats was moved to intermediate rearing sites at Yangyang fishing port in Gangreung-city for acclimation to ocean environments. The highest survival rate of attached spats was 13.0% shown at the group reared for 12 days, but the significant difference in their growth was not found between the groups. The shell length of artificial attached spats increased from 0.9 ${\mu}m$ on July 10th to 24.7 ${\mu}m$ on December 16th with the survival rate of 85.0% while that of natural attached spats increased from 0.6 ${\mu}m$ on July 10th to 23.9 ${\mu}m$ on December 16th with the survival rate of 85.7%.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.6
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• pp.468-477
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• 2019

The numerical model of Boussinesq approximation, which is mainly used for evaluating the port calmness due to the irregular waves, has a limit of applicability of lattice size in ports such as marinas with narrow port openings of around 30m. The SWASH model controls the partial reflection according to the depth, porosity coefficient and structure size when applying the reflected wave incident on the structure and terrain. In this study, the partial reflection evaluation at the front of the structure according to the bottom shape and the shape of the structure are examined. In order to evaluate the reproducibility of the model due to the diffraction waves entering the term, the area of incidence at right angles and inclination of the structure is constructed and compared with the diffraction theory suggested by Goda et al. (1978). The experimental results of the sectional structure reflectances calculated as the depth mean show reflectances similar to the approximate values of the reflectances presented by Stelling and Ahrens (1981). It is considered that the reflected wave is well reproduced according to the control of the reflected wave at the boundary and the shape and topography of the structure. Compared with previous studies to examine the diffraction of the wave incident from the breakwater opening, the wave incidence angle and the shape of the diffraction wave are very similar to the theoretical values, but both oblique and rectangular incidence In the case where the direction concentration is small, the diffraction degree is underestimated in some sections with the crest ratio of 0.5 to 0.6.

• 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.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.336-341
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• 2000

This study was conducted to clarify the habitat characteristics and distribution of seagrass. Zostera marina L. (Zosteraceae) in the brackish Hwajinpo Lake, Korea in June 1998 and July 2000. Z. marina beds were distributed along the sea-side cost of the lower lake mouth at 0.8 to 1.5m in death, and the seagrass bed area was about 3,200 m$^{2}$. Salinity, water temperature and pH were in the range of 8.0${\sim}$23.0$%_{o}$, 22.0${\sim}$23.7$^{\circ}C$ and 8.34${\sim}$8.62, respectively. Nutrient concentrations were generally now (TN: 24.34 ${\mu}$M, NH$_{4}$-N: 2.57 ${\mu}$M, NO$_{3}$-N: 0.56 ${\mu}$M, NO$_{2}$-N: 0.27 ${\mu}$M, TP: 2.08 ${\mu}$M, PO$_{4}$-P: 0.34 ${\mu}$M). Suspended particulate matters (SPM) concentration averaged 62.8 mg/l and particulate organic matter (POM) averaged 21.3 mg/l. Organic content of SPM averaged 33.9%. The beds substratum was composed of well-sorted, fine sand and its mean brain size was 3.13${\Phi}$. The Z. marina vegetation was almost submerged, and the morphological characteristics can be classified as steno-leaf phenotype by the shoot length, leaf width, and number of leaf vein. Shoot length and leaf width were 70.0${\sim}$126.5 cm and 5${\sim}$7 mm, respectively. Shoot densities ranged from 264 to 296/m$^{2}$, and the plants biomass was estimated at 332.6 to 373.0 g dw/m$^{2}$. Therefore, the habitats of Z. marina in Korea were recognized in a brackish lake, and morphological characteristics appeared to be variable.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.149-157
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• 2003

This study focused on relationships between Pb and Cd concentrations and the difference of success reproductive progress in urban (Seoul) and industrial complex (Ansan) areas. Results of the Pb analysis for the feral pigeons from Seoul (egg contents:1.64 $\mu\textrm{g}$ wet $g^{-1}$, adults in bones: 29.5 $\mu\textrm{g}$ wet $g^{-1}$ and the Ansan industrial complex (egg contents: 1.13 $\mu\textrm{g}$ wet $g^{-1}$, adults in bones: 10.5 $\mu\textrm{g}$ wet g-1) showed that the Pb level of eggs and adults is significantly different between the two colonies (p<0.05). Cd concentrations in liver and kidneys of adult pigeons were also significantly different between Seoul(liver: 0.24 ${\mu}g$ wet $g^{-1}$, kidney: 1.05 $\mu\textrm{g}$ wet $g^{-1}$ and the Ansan (liver: 0.14 $\mu\textrm{g}$ wet $g^{-1}$, kidney: 0.43 $\mu\textrm{g}$ wet $g^{-1}$ colonies (P<0.05). Clutch size of Feral Pigeons living in Seoul was similar between the two colonies, 1.9$\pm$0.3 in Seoul and 2.0$\pm$0.0 in Ansan. The length, breadth, and thickness of eggs were not significantly different between the two colonies (p>0.05). Incubation period in Seoul (17.8 days) did not differ from the Ansan (17.4 days). No difference in growth rate (body weight, wing length, and tarsus length) was found between the two test groups (p>0.05). In Seoul, 65.2% were hatching, and 42.1% fledging. The Proportion of hatching and fledging in the Ansan was 60.7% and 45.0%, respectively. The significant differences between the two colonies for reproductive sucess were not found (p>0.05). With regard to the reproductive effects to the heavy metals, the Pb and Cd concentrations feund in the two colonies were not as high as those considered in results of toxic effects in other species.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.57-65
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• 2004

In order to determine the effect of fresh water inflow from the Heongsan river on the changes of water quality in the Yeongil Bay (Korea), the seasonal changes of water temperature, salinity, chemical oxygen demand (COD), dissolved inorganic nitrogen(DIN) and phosphate phosphorus ($PO_4$-P) concentrations were examined using the data set obtained five fixed points of Yeongil Bay from 1998 to 2000. The distributions and changes of COD and concentrations of total inorganic phosphorous (TIP) and nitrogen (TIN) at three points Heongsan river, were also compared with those of Yeongil Bay. Based on the correlations of DIN and $PO_4$-P, it was found that the inflow of freshwater affected on the water quality of Yeongil Bay. Such a complicacy was confirmed by the prominent differences in n few water quality measures between Site 1(the innermost area) and Site 5 (the mouth of the bay). The negative correlations in $\Delta N/\Delta P $ at sites 1, 2 and 3 of the inner-part of the bay also indicated a large effect of freshwater inflow on the water quality of the bay. The extremely low atomic ratio of an average of 6.4 in $\Delta N/\Delta P $ compared to the Redfild ratio suggested that the DIN was depleted in the overall bay system. In contrast, it was inferred that the excessive PO$_4$-P concentration was due to the inflow of freshwater from the Heongsan river.

• Applied Microscopy
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• v.38 no.3
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• pp.167-174
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• 2008

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disease that often has asthma and allergic rhinitis. Magnesium salts, the important component of minerals in Dead Sea water, are known to exhibit beneficial effects in inflammatory disease. Favorable effects of magnesium ions and sea water treated to the skin of patients with contact dermatitis have been reported. But histological and immunological investigations are insufficient. This study was performed to examine the inhibitory effect of magnesium-rich sea mineral water on the development of AD-like skin lesions in hairless mice. AD-like skin lesions are induced by the repeated application of 2,4-dinitrochlorobenzene (DNCB). Local application of magnesium-rich sea mineral water on hairless mice skin applied with DNCB inhibited the development of AD-like skin lesions as exemplified by a significant increase in skin hydration (p<0.01), and a decrease in epidermal water loss (p<0.01). Serum IgE level was also significantly decreased (p<0.01). These results suggest that magnesium-rich sea mineral water inhibits the development of DNCB-induced AD-like skin lesions in hairless mice. These observations indicate that magnesium-rich sea mineral water may be alternative and assistant substances for the management of AD.

• 한국해양학회지
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• v.28 no.3
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• pp.212-228
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• 1993

A chenier, about 860 m long, 30 to 60 m wide and 0.6∼1.6 m high, occurs on the upper muddy tidal flat in the Gomso bay, western coast of Korea, It consists of medium to fine sands and shells with small amounts of subangular gravels. Vertical sections across the chenier show gently landward dipping stratifications which include small-scale cross-bedded sets. the most probable source of the chenier is considered to be the intertidal sandy sediments. Vibracores taken along a line transversing the tidal flat reveal that the intertidal sand deposits are more than 5 m thick near the low-water line and become thinner toward the chenier. The most sand deposits are undertrain by tidal muds which occur behind the chenier as salt marsh deposits. C-14 age dating suggests that the sand deposits and the chenier are younger than about 1,800 years B.P. The chenier has originated from the intertidal sand shoals at the lower to mid sand flat, and has continuously moved landward. A series of aerial photographs (1967∼1989) reveal that intertidal sand shoals (predecessor of the western part of chenier) on the mid flat have continuously moved landward during the past two decades and ultimately attached to the eastern part of the chenier already anchored at the present position in the late 1960s. Repeated measurements (four times between 1991 and 1992) of morphological changes of the chenier indicate that the eastern two thirds of the chenier, mostly above the mean high water, has rarely moved whereas the western remainder below the mean high water, has moved continuously at a rate of 0.5 m/mo during the last two years (1991∼1992). This displacement rate has been considerably accelerated up to 1.0 m/mo in winter, and during a few days of typhoon in the summer of 1992 the displacement amounted to about 8∼11 m/mo for the entire chenier. these facts suggest that macro-tidal currents, coupled with winter-storm waves and infrequent strong typhoons, should play a major role for the formation and migration of chenier after 1,800 B.P., when the sea level already rose to the present position and thereafter remained constant.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.226-236
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• 1999

Growth, reproduction, mortality, and production of Laminaria japonica were experimentally studied at a cultivation ground on the coast of llkwang, where the largest amount of cultivated Laminaria has been produced in Korea. For this experiment, young sporophytes (0.33 cm in mean length) grown in the laboratory were transplanted at the depth of 3 m and field surveys on them were conducted twice a month from December, 1995 to August, 1996. Plants exhibited an annual life span; they were completely dead by August. Frond width, thickness, and wet weight showed similar pattern of seasonal growth and reached their maxima in July, but frond length showed no more increment after May. Maximum mean frond length and weight were 199.8 cm and 333.0 g wet wt., respectively. Overall meristematic growth in length and weight were 384.0 cm and 393.6 g wet wt., respectively. Absolute growth rates (AGR) which were calculated from the length of tissue developed from meristem varied seasonally; AGR of length and weight reached maxima in March (3.6 $cm{\cdot}d^{-1}$) and May (3.8 g wet $wt{\cdot}d^{-1}$), respectively. Absolute attrition rates gradually increased from February to July. Seasonal differences in growth and attrition rates appeared to be related to seawater temperature and nitrogen concentration in seawater. Reproductive sporophytes bearing sprorangium sorus began to occur from April, and the ratio of sorus area to blade area reached its maximum in July (0.034). Survival rate was exponentially decreased; more than 90% of plants decayed within 56 days after outplanting. After February, mortality was size-specific; mortality of smaller plants less than 30 cm in length were relatively higher. Maximum biomass occured in July (285.6 kg wet $wt{\cdot}m^{-2}$) and annual production was 758.7 kg wet $wt{\cdot}m^{-2}$.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.3
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• pp.180-190
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• 2014

It has been customary to exclude top 10-20% of velocity profiles in the Acoustic Doppler Current Profiler (ADCP) measurement due to side lobe effects at the boundary. To better understand the mixing in the Yeongsan estuary, the freshwater advection speed (FAS) was recovered from highly contaminated ADCP data near the surface. The velocity profiles were measured by using ADCP at two stations in the Yeongsan estuary during August 2011: one was located in front of the Yeongsan estuarine dam and the other was deployed near Goha Island. The FAS was recovered from the ADCP data set by applying rigorous post-processing methods and compared with the sediment advection speed (SAS). The SAS was determined by the peak time difference of suspended sediment concentration between two stations in the channel, divided by the distance of two stations. The FAS and the SAS showed very similar value when the freshwater discharge was greater than $2.0{\times}10^7$ ton and the SAS was a bit greater when the freshwater discharge was smaller. Since the FAS was on average about 0.8 m/s greater than the velocity at 0.8 of water depth from the bottom, the net discharge, estimated with recovered FAS and integrated over water depth and tidal cycle, was directed seaward during the high discharge contrary to the onshore direction of the net discharge estimated with 0.8 of water depth from the bottom. Moreover, the velocity shear and Richardson number changed when the FAS was used. Thus, the importance of the true FAS is appreciated in the investigation of the surface layer stability. If currents, temperature and salinity were observed for longer time in the future, it could be possible to more accurately understand the formation and decay of stratification as well as the suspended sediment transport processes.