• Journal of The Korean Society of Grassland and Forage Science
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• v.12 no.3
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• pp.161-172
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• 1992

The agronomic performance of four introduced corn(Zea mays L.) hybrids and a domestic hybrid Suwon 19(control) was compared for silage production in the Middle Northwestern Coast(MNWC). Middle Southwestern Coast(MSWC) and Middle Northern Inland(MN1) regions of Korea, 1988 to 19 90. In the MNWC region, DK713 and P3144W were recorded as more resistant corn hybrids to rice black streaked dwarf virus(RBSDV) than other hybrids. P3144W, P3352 and DK689 hybrids produced higher dry matter(DM) and total digestible nutrient(TDN) than the control hybrid Suwon 19 and DK 713. In the MSWC region, P3144W and DK689 tended to yield more DM and TDN than other hybrids and a severe infection of RBSDV was observed during 3 years of experiment. In the MNI region, P3144W and P3352 corn hybrids showed higher ear and dry matter percentage and gave the highest DM and TDN yield compared with other hybrids. The RBSDV infection of the hybrids in the MNI region was moderate level compared with the two regions, but rate of stay green was the lowest. In the three regions, the control hybrid Suwon 19 gave the highest RBSDV infection, followed by P 3352, DK689, and P3144W, while DK713 was the lowest. P3144W and P3352 hybrids gave higher DM and ear percentages than all other hybrids at harvest. During 3 years of experiment, it was found that there were regional and year differences in RBSDV infection, forage DM yield, DM percentage and ear ratio to total DM yield of the corn hybrids.

• Journal of the korean society of oceanography
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• v.32 no.4
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• pp.181-190
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• 1997

A large subtidal sand ridge (Jungang Satoe) in Asan Bay, on the west coast of Korea, was studied in order to understand the morphology and sediment transport trend in a macrotidal setting, by means of analyzing sediment samples, current data, side-scan sonographs and seismic profiles. The ridge is about 15 km long and 2-5 km wide, with a relief of about 15 m. It is elongated in the flow direction of flood (SE) and ebb (NW) tidal currents, but asymmetrical in cross section. The western and southwestern side of the ridge is characterized by relatively gentle slopes averaging 0.4$^{\circ}$, whereas on the northeastern side, relatively steep slopes were mapped with 1.6$^{\circ}$ slope angles. Tidal currents associated with the ridge are very strong; maximum surface velo-cities range from neap values of 50 cm/s to spring values of 130 cm/s. The shear velocities during flood and ebb are strong enough to erode and transport sands on the ridge. Sand waves and megaripples (dunes) are the most common bedforms produced by the tidal currents, which show regional differences in shape and size on the ridge. The distribution pattern of these bedforms in-dicates that the flood tidal currents are dominant on the offshore (northwest) side of the ridge, whereas the onsho.e (southeast) side of the ridge is ebb-dominated. The sand transport path as inferred from bedform orientations is directed toward the ridge crest on the flanks, whereas on the crest, it is near-longitudinal to the ridge axis. The convergent, upslope movement of sands on the ridge flanks appears to be important in sand ridge building and maintenance. A significant ridge migration toward the northeast can be suspected on the basis of the ridge morphology, which may cause offshore hazards for navigation.

• 한국해양학회지
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• v.28 no.1
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• pp.1-16
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• 1993

The monthly mean sea levels at 48 stations located at the East and Yellow Seas coasts of Korea, Russia and Japan are processed to investigate seasonal sea level variations. The strong seasonal variations are found to be at the west coast of Korea (42.1 cm in Kunsan), in the region of the Korea strait and near the southern part of Primorye (30-33 cm); the weak ones near the southwestern coast of the Sakhalin Island (10-12 cm). Practically for the whole study area except the southwest Sakhalin, the general picture of the seasonal sea level changes is alike: the mean sea level rises in summer-autumn and falls in winter-spring. The spectral analysis of the records also shows that the seasonal oscillations strongly dominate in the sea level variations, more than 80% or total energy in the southern part of the investigated region and 50-70% in the northern part relate to these oscillations. The annal peak significantly prevails in spectra of the monthly sea levels for the majority of stations, the semiannual peak is also well manifested, but the seasonal peaks of higher order (corresponding to the periods of four and three months) reveal only at some records. The maximal amplitudes of annual component by a least square method are found at the Yellow Sea coast of Korea (20-21 cm) and also near the Japanese coast of the korea Strait (19-19 cm). The semiannual component has the maximal amplitudes (3-4 cm) near the south and southwestern coasts of the Sakhalin Island. The annual range of the sea levels is much weaker here than in the other regions, the relative investment of the seasonal oscillations in total energetic budget is only 35-40%, annual ($A_1$) and semiannual ($A_2$) components have nearly the same amplitude (seasonal factor $F=A_1/A_2=0.9-1.2$). On the basis of the present examination on sea level changes together with the results of Tomizawa et. al.(1984) the whole investigated area may be divided into 10 subregions, 2 of them are related to the Yellow Sea and Western part of the Korea Strait (Y1, Y2), the other ones (E1-E8) to the East Sea.

• Journal of the Korean Society of Earth Science Education
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• v.8 no.3
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• pp.251-258
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• 2015

Ecosystems of the southwestern tidal flats in Korean peninsula have been seriously injured by human activities. The results are mainly due to the lack of public recognition and education on tidal flats. In particular, thoughtless visitors in tidal flats are giving rise up damages because of non-systematic experience programs to tidal flat ecosystems. Therefore, experience programs friendly to natural tidal flats are necessary as a plan to reserve tidal flats and to enhance the effects of environment education on the flats. Experience learning programs on tidal flats can divide into direct experience, indirect experience and local society works. Direct experience work must undergo tidal flats directly and consider on forming the flats with natural refinement functions. Indirect experience includes deeper knowledge on role, circumstance and ecosystems of the flats on the bases of direct experience on the flats. In addition, local society learning must have the feeling and understanding on socio-cultural characteristics of local society itself through above two works. Experience activity would be a kind of injuring one to tidal flats. However, appropriately planned experience and education works on tidal flats could be sustainable development to attract desirable human activity on coastal ecosystems.

• Journal of Environmental Science International
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• v.13 no.2
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• pp.135-141
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• 2004

Drift data from 17 Argo profiling floats in the East Sea are used to understand the mean flow and its variability in the upper portion of the East Sea Proper Water (UESPW) (around 800 m). The flow penetrates into the Ulleung basin (UB) through two paths: an extension of the southward flowing of the North Korean Cold Water along the east coast of Korea and between Ulleung Island and Dok island. Flows at 800 m are observed in the range of from 0.2 to 4.29 cms-1 and the variability in the north of the UB is larger than that in the south of the UB. In the UB, cyclonic flows from 0.3 to 1.6 cms-1 are observed with the bottom topography. We found that the mean kinetic energy (MKE) and the mean eddy kinetic energy (EKE) are 1.3 and 2.1 cm2s-2 respectively.

• Korean Journal of Environmental Biology
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• v.30 no.3
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• pp.193-199
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• 2012

We performed qualitative and quantitative surveys on the distribution of seaweed species and dominant species with their standing crop and temporal variations in Hauido tidal flats in order to understand the role of seaweeds in a coastal wetland ecological system that may be used for conservation and management of coastal wetland ecological system. A total of 9 species were found at 7 stations of the study area; 4 species of Chlorophyta (Ulva compressa, U. prolifera, U. pertusa and Ulothrix flacca), 3 species of Phaeophyta (Ectocarpus arctus, Scytosiphon lomentaria and Myelophycus simplex) and 2 species of Rhodophyta (Gracilaria verrucosa and Caulacanthus okamurae). Major dominant species were U. compressa, U. prolifera and U. pertusa (Chlorophyta), Scytosiphon lomentaria (Phaeophyta) and Gracilaria verrucosa (Rhodophyta). Standing crops of U. compressa and U. prolifera were $2.94{\sim}45.25g{\cdot}dw{\cdot}m^{-2}$ and $6.19{\sim}91.9g{\cdot}dw{\cdot}m^{-2}$, respectively, in spring. Seaweed habitat was characterized by textural differences that the percentage of coarse particles and organic material were a little higher in seaweed flourishing areas than in seaweed barren areas.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.1
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• pp.1-14
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• 2015

This study investigates the impact of enhanced regional meteorological fields on improvement of wind energy forecasting accuracy in the southwestern coast of the Korean Peninsula. To clarify the effect of detailed surface boundary data and application of analysis nudging technique on simulated meteorological fields, several WRF simulations were carried out. Case_LT, which is a simulation with high resolution terrain height and land use data, shows the most remarkable accuracy improvement along the shoreline mainly due to modified surface characteristics such as albedo, roughness length and thermal inertia. Case_RS with high resolution SST data shows accurate SST distributions compared to observation data, and they led to change in land and sea breeze circulation. Case_GN, grid nudging applied simulation, also shows changed temperature and wind fields. Especially, the application of grid nudging dominantly influences on the change of horizontal wind components in comparison with vertical wind component.

• Korean Journal of Environmental Biology
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• v.22 no.4
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• pp.524-531
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• 2004

Photosynthetic activities and primary production of phytoplankton were investigated in Lake Gocheonam from October 1999 to August 2000. As an estuary lake with a barrage in the Southwestern coast of the Korean peninsula, the lake has received more attention after it became known as the habitat of large population of rare and endangered bird- Baikal Teal. As the lake had high algal biomass ranging from $20\mu{g}\;chl-aL^{-1}\;to\;125\mu{g}\;chl-aL^{-1}$ in average values and rich eutrophication indicator species, the freshwaters were in a very productive or hypertrophic state. In the results obtained from the phytoplankton incubation in the laboratory, the maximum photosynthetic rate $(P_{max})$ varied according to seasons and sampling stations. Photo- synthetic activities were higher during the warm season than the cold seasons and the serial order of $P_{max}$ was August dominated with Microcystis, April with Chlamydomonas and Nitzschia, October with Chlamydomonas and January with Stephanodiscus. The water of the lake was persistently turbid throughout the year due to strong winds from the adjacent sea. Despite the water turbidity, the phytoplankton productions estimated from a mathematical model had very broad range from 18mg C $m^{-2}day^{-1}\;to\;10,300mg\;C\;m^{-2}day^{-1}$.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.1
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• pp.300-307
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• 2015

Seasonal variation in marine macroalgal community structure was examined at the intertidal zones of Geumgap, Jindo, Korea, from October 2013 to August 2014. In total, 56 macroalgal species were identified, including 9 green, 12 brown, and 35 red algae. Annual seaweed biomass was 548.96 g wet wt. /$m^2$ with seasonal range between 371.08 g wet wt. /$m^2$ at summer and 32.91 g wet wt. /$m^2$ at winter. The dominant seaweed in terms of biomass was Sargassum thunbergii and subdominant species were Gelidium elegans, Sargassum fusiforme, and Ishige okamurae. The vertical distribution of seaweeds from the upper to lower intertidal zones was Gloiopeltis spp., Ulva spp.- S. thunbergii, S. fusiforme, Ishige okamurae - S. thunbergii, S. fusiforme, G. elegans. Annual seaweed coverage, richness index (R), evenness index (J'), and diversity index (H') values were 27.95%, 6.10, 0.38, and 1.38, respectively. Coarsely branched form was the most dominant functional group in terms of species number and biomass among benthic macroalgal species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.2
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• pp.207-218
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• 2017

Seawater with salinity of 32.5 psu or less is observed in the southern Japan/East Sea (JES) every autumn. It is confined to a surface layer 30-45 m in depth that expands to cover the entire JES in October. Two sources of "autumn low-salinity water" have been identified from historical hydrographic data in the western JES: East China Sea (ECS) water mixed with fresh water discharge from the Yangtze River (Changjiang) and seawater diluted with melted sea ice in the northern JES. Low-salinity water inflow from the ECS begins in June and reaches its peak in September. Low-salinity water from the northern JES expands southward along the coast, and its horizontal distribution varies among years. A rare observational study of the entire JES in October 1969 indicated that water with salinity less than 33.0 psu covered the southwestern JES; the lowest salinity water was found near the Ulleung Basin. In October 1995, the vertical distribution of salinity observed in a meridional section revealed that water with salinity of 33.6 psu or less was present in the area north of the subpolar front.