• Korean Journal of Ichthyology
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• v.1 no.1_2
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• pp.1-8
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• 1989

In August, 1988, matured adults of devil stinger were collected from Jinhae Bay and Jaran Bay, Kyongsangnam-do, Korea and kept in the aquarium (1 ton) for spawning. The egg development was observed with the eggs laid in the aquarium of adult fish. The diameters of eggs ranged from 1.2 to 1.3 mm (n=6), and no oil globules were found in the eggs. The hatching took place from 26 to 29 hours after eight cells stage at the water temperature of $24.9-26.5^{\circ}C$. The newly hatched larvae were 2.47~3.10 mm in total length with xanthophore on the body and yolk sac. Myomere number was 13+16-17=29-30. Two days after hatching, larvae were 3.61-4.16 mm in total length, and 3 to 4 large spots of melanophore appeared on the large pectoral fin. Three days after hatching, larvae were 3.97-4.29 mm in total length, and the larvae absorved the yolk material completely to become post larvae with 4-5 rays of the pectoral fin. Six days after hatching, larvae attained 4.07-5.46 mm in total length, and 11 rays and 8-9 spots of melanophore were developed on the pectoral fin.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.4
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• pp.330-348
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• 2007

Soil problems and agricultural water management of the reclaimed land in Korea were reviewed through research results conducted in RDA and ADC. According to the Korean Soil Classification and Soil Survey(NIAST, 2002), the 5 soil orders with the 45 soil series were distributed on the fluvio-marine or marine deposit of the west and south coastal plains. Yeompo, Munpo, Hasa, Gwangwhal, and Poseung soil series were most commonly distributed soil on the fluvio-marine deposits, associated with tideland of the sea coast. Former 4 soils were Entisols, and the latest one was the Inceptisols. Buyong soil associated with Poseung series was an Alfisols. Extent of Myeongji soil, a Molisols, and Yongho soil, a Histosol, were minor. Salinity control and management problems were closely related with high water table and low percolation rate due to plow-pan layer developed during the leaching process in the silty textured soil. For evaluation of field salinity, use of an electromagnetic inductance, EM38, with GPS was helpful to understand salinity status and field variability. Deep plowing, subsoiling and drainage improvement by tile drainage might be effective in paddy with plow-pan. New technology such as variable rate fertilization might save fertilizers and thus reduce environmental impact of agriculture on water quality. Water quality of agricultural water resources in reclaimed land was less adequate than that of inland water resources. Proper crop management is necessary depended upon quality for crop growth as well as to match with water quality target.

• Journal of the Korean Geographical Society
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• v.48 no.1
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• pp.37-55
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• 2013

Previous studies have shown that Foehn was mainly observed in Young-seo area in Korea. However, they have failed to indicate the area where Foehn can be observed most frequently in Young-seo area and how Foehn is distributed in that area. This study targets HongCheon area in Young-seo province and examines the frequency and extent of Foehn in local scale through documenting a daily maximum air temperature map of Foehn. The period examined in this study is the months between March and June from 2003 to 2012. CoKriging method, which uses temperature and the altitude above sea, generates a higher level of accuracy in making daily maximum air temperature map of Foehn occurring days. We have found that Foehn is observed in certain areas, not all areas of HongCheon region, by compiling the daily maximum air temperature map. In particular, Foehn was found to be frequent and strong in the downstream of HongCheon river. In addition, we surveyed the residents of HongCheon about their perception of Foehn. They did not know whether high temperature and dryness in spring are caused by Foehn. The methods and techniques used to examine Foehn in local climate scale by this study will enhance the understanding of regional climate and contribute towards the research in this area. In particular, they can be applied to high temperature that recently occurred between spring and summer, excessive hotness in summers, agricultural plant growth in springs and etc.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.2
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• pp.187-193
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• 2017

This study evaluated tidal stream energy resources according to tidal flow properties around Uido off the west coast of, Jeollanam-do, South Korea. A feasibility study was first carried out through the collection of bathymetry data and tidal phase information. For this simulation, a depth-averaged 2D ADCIRC (Advanced Circulation) model for real sea situations was applied to a Finite Element Method (FEM) approach for tides given the variation of tidal current speed. Hydrodynamics were simulated with 4 major tidal constituents (M2, S2, K1, and O1) after setting up 4 observation points. From the real depth-averaged model simulation results, it was found that the spring tide Higher High Water (HHW) and tidal current speed values at the 4 observation points were about 2.2 m and 1.33 m/s, respectively. The ADCIRC model results were analyzed with reference to the Korea Hydrographic and Oceanographic Agency's (KHOA) observed data for verification. Furthermore, using topographical characteristics via the Tidal Flux Method (TFM), tidal energy density distribution was calculated, indicating a maximum tidal energy density of about $1.75kW/m^2$ for the 5 assessment areas around Uido. The tidal energy density was evaluated with consideration given to topographical characteristics as well as tidal elevation and tidal current speed to determine an optimum tidal farm candidate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.20-31
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• 2024

This study was conducted to investigate the changes in the structure of benthic communities resulting from aquaculture activities and to assess the benthic health status of surface sediment in Gangjin Bay, a region known for concentrated shellfish aquaculture on the southern coast of Korea. Survey stations were divided into longline culture, bottom culture, and non-cultivation areas. The spatiotemporal distribution of physiochemical factors such as the grain size, water temperature, salinity, and total organic carbon in Gangjin Bay showed no significant differences between sampling stations. However, the species number, density, and diversity were relatively lower at the sampling stations in the bottom culture areas than at the other stations throughout the entire survey period. Cluster analysis and principal coordinates analysis also clearly distinguished the benthic communities in the bottom culture areas from those in the other sampling areas. At the sampling stations in the longline culture and non-cultivation areas, Scolectoma longifolia and Sigambra tentaculata, which are indicator species of organically enriched areas, appeared as dominant species. However, excluding some stations influenced by physical factors such as the water depth and current speed, the occupancy rate was not high. The health assessment results, conducted using the fisheries environment assessment method, revealed good conditions with Grades 1 and 2 across the entire area. However, an examination of the spatiotemporal changes in benthic communities and the benthic health index indicated that the benthic environment in the bottom culture areas was affected by physical disturbances.

• The Korean Journal of Quaternary Research
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• v.24 no.2
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• pp.23-34
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• 2010

The purpose of this study is to clarify the characteristics of geomorphic surfaces and investigate their geomorphological development at Sinsong-ri archaeological sites by the classification of geomorphic surfaces. The sedimentary facies of trench 1, 2 and 3 were identified and pollen analysis was performed at site 3. The geomorphic surfaces are classified by hillslope, valley plain, alluvial fan and river terrace. Most of the study area is located on low hillsides and valley plains are connected with tidal flats extended from small river valley. Also, alluvial fans are distributed over the piedmont and narrow, long river terraces are developed downstream along the Sojeong-stream flowing between valley plain and hillsides. River valleys were deeply eroded during the Last Glacial Maximum (LGM) periods, responded to the lowest sea level among the hillslopes and valley plains are formed during the Holocene. The sedimentary facies are identified composed of basal gravel layers with coarse gravels and sands, relatively thick culture layer of the Bronze Age and thin layer during the early Iron Age in upper part study area. Thus, land uses during the Bronze Age people was performed more intensively comparing to the early Iron Age by deforestation for habitation.

• Korean Journal of Ecology and Environment
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• v.41 no.1
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• pp.11-18
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• 2008

Seasonal succession and community composition of planktonic ciliates were studied in Kyungan Stream from December 2000 to December 2001. Oligotrichs accounted for 53% of total ciliates. Total abundance of ciliates peaked in spring (30 March, 6 April) and in summer (8 June, 20 July) reaching values up to $1.9\times10^4$ cells $L^{-1}$. Seasonal succession of dominant species occurred obviously. Large-sized $(>50{\mu}m)$ species (Stylonychia sp1, Phascolodon vorticella and Codonella cratera) dominanted from winter to spring. Small sized $(<30{\mu}m)$ species (Vorticella spp., Rimostrombidium hyalinum and Halteria grandinella) dominanted in summer and autumn. Total abundance of large-sized species coincided with the Chl-${\alpha}$ concencetation during the study (r=0.33, p<0.05, n=39). Among the small-sized species Halteria grandinella was a significant relationship with bacterial abundance (r=0.35, p<0.05, n=39).

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.496-503
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• 2021

Pinus densiflora is an essential tree species native to the Republic of Korea (ROK) and covers most of the total natural forest areas in the ROK. This study was conducted to understand the site characteristics and stand structure of P. densiflora forests distributed at sites where P. densiflora covered over 50% of the stand basal area during the 7th National Forest Inventory (NFI) period from 2016 to 2020. P. densiflora dominated 3,665 circular sample plots (400 m²). P. densiflora forests predominated at elevations less than 600 m above sea level (a.s.l). However, most P. densiflora forests were distributed at the slopes facing south and west over 800 m a.s.l. At altitudes below 800 m, they were distributed at all slopes but dominated at the southern and western slopes. P. densiflora grew mainly in the soils of sandy loam, loam, or silt loam with relative infertility. Dominant tree species distributed with P. densiflora were Quercus mongolica, Q. variabilis, Q. serrata, Prunus serrulata var. pubescens and Castanea crenata by the descending order. P. densiflora, P. thunbergii, and P. rigida were grown in large DBH classes, Quercus species and Fraxinus rhynchophylla in middle DBH classes, while Juniperus rigida and Styrax japonicus in small DBH classes. Dominant tree species distributed mainly at the lower layer of P. densiflora stands were Rhododendron mucronulatum, Q. serrata, Lindera obtusiloba, Fraxinus sieboldiana, Toxicodendron trichocarpum and Rhododendron schlippenbachii by the descending order.

• The Korean Journal of Malacology
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• v.21 no.1
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• pp.71-80
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• 2005

We investigated the reproductive cycle with ovarian development of Chlamys farreri by histological observations, and seasonal changes in biochemical components of the adductor muscle, digestive diverticula and ovary were studied by biochemical analysis. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (March to April), ripe stage (April to August), partially spawned stage (June to August) and spent/inactive stage (August to January). According to ANOVA test, there were significant differences (p < 0.05) in total protein, total lipid and glycogen contents among months for all of the adductor muscle, digestive diverticula and ovary. Total protein contents in ovary and digestive diverticula showed significant changes (ANOVA, p < 0.05) during the study period, while that in the adductor muscle did not. Total protein content was highest in the adductor muscle, followed by ovary, and lowest in digestive diverticula. There was no correlation in total protein content between the adductor muscle and digestive diverticula (p = 0.220). But strong positive correlation was found between adductor muscle and ovary (r = 0.450, p = 0.013). ANOVA showed that there were significant differences in total lipid and glycogen contents among months for all of the adductor muscle, ovary, and digestive diverticula (p < 0.05). The monthly changes in total lipid content were highly variable in ovary and digestive gland. High contents of total lipid were found during April and May-June in ovary, while March and June-July in digestive diverticula. There was a strong negative correlation in total lipid content between ovary and digestive diverticula (r = -0.397, p = 0.030). Unlike total protein or total lipid, glycogen content in the adductor muscle was most dynamic. It showed more than 36-fold changes in the adductor muscle (at most 3-fold change in ovary) during the study period. Glycogen content was higher during May-July in the adductor muscle, while it was higher in March and August in digestive diverticula. There was a strong negative correlation in glycogen content between the adductor muscle and digestive diverticula (r = -0.584, p = 0.001).

• Ecology and Resilient Infrastructure
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• v.5 no.3
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• pp.118-124
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• 2018

Social infrastructures and industrial complexes have been actively constructed in South Korea since the 1960 s as part of the economic development plan, resulting in rapid industrialization. However, side-effects due to the industrialization have occurred. An increase in industrial by-products or wastes is a typical problem. Although some industrial by-products are recycled in Korea as well as worldwide, some wastes are landfilled or dumped in the sea. Although many researchers have executed various technologies for the disposal of industrial wastes, economic and environmental technologies have not been developed. Thus, this study aims to activate paper and fly ashes during the crush process to overcome the drawback of simple concrete mixed with paper and fly ashes, which cause a reduction in workability and strength, derive an optimal content and replacement ratio of concretes mixed with Energetically Modified Material (EMM), and evaluate the material performance. In addition, the basalt fiber is mixed simultaneously to achieve the reduction of cracks and improve the tensile strength.