• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.444-452
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• 2009

Textural parameters were calculated from the surface sediments collected from Jinu-do beach in Nov. 2005 and May 2006. In Nov. 2005 and May, 2006, the grain size distribution of surface sediments shows that the mode of $3.0\phi$(i.e., 0.125 mm) dominated the west beach of Jinu-do, but in the east beach the mode of $3.0\phi$(i.e., 0.125 mm) decreased and the mode of $2.5\phi$(i.e., 0.177 mm) was apparently distinct, resulting in the more coarsening trend. Mean grain size of surface sediments also indicates little difference in the west beach between two investigations, but the increasing difference between mean grain sizes in the east beach, showing more coarsening pattern. Such seasonal pattern corresponds to the positive skewness in the east beach in May, 2006. As a result, after the winter in 2005, the surface sediments in the west beach of Jinu-do experienced a little variation, whereas the apparent coarsening of surface sediments occurred in the east beach by removal of $3.0\phi$(i.e., 0.125 mm) fine-grained sand particles. The observed seasonal change may be attributed to the different hydrographic condition and sediment delivery/removal on the surface sediments between the west beach and the east beach of Jinu-do through the increased precipitation and more freshwater discharge from the Nakdong River during the summer and the intensified wave and tide during the winter in the Nakdong River estuary.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.47-51
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• 2006

This study was conducted to establish the optimum seeding rate in different soil salinity level for yield stability of broadcasting on flooded paddy surface to the reclaimed saline land of south-western part at Gyehwado substation of the Honam Agricultural Research institute in $2003{\sim}2004$. Soeganbyeo was tested in the Munpo series (fine sand loam) the results obtained is as follows: As seeding rate was higher, the number of seeding stand was increased and the number of seeding stands in the low salinity field is sharply increased than those of the medium salinity field. The length of culm in medium salinity field tends to be shorter than that of the low salinity field and as seeding rate was increased, the lodging is severe. The milled rice yield was increased as up to 9 kg/10a in low and medium salinity soil. Complete rice was no significantly increased over 5 kg/10a seeding rate in low salinity field and over 7 kg/10a seeding rate in medium salinity field. Considering the yield of milled and complete rice, seeding stand and lodging, The proper seeding rate is $5{\sim}7kg/10a$ in low salinity and $7{\sim}9kg/10a$ in medium salinity for broadcasting on flooded paddy surface at the reclaimed saline land of southwestern part.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.3
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• pp.167-172
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• 1990

Some of soil properties already known were selected for the determination of their effect on soil moisture characteristics. Total number of 2,808 representative samples from all over Korea with the exception of Jeju Island were investigated. 1. Available water contents were 4.7 for S, 7.7 for LS, 13.2 for SL, 17.7 for L, 19.2 for SiL, 15.9 for CL, 14.5 for SCL, 18.7 for SiCL, 17.3 for SiC, and 14.9% for C, respectively. 2. Simple regression analysis showed that field capacity and available water content were most strongly associated with sand content in coarse-textured soils, and with organic matter content in fine-textured soils, whereas permanent wilting point was closely associated with clay content. 3. Available water was strongly associated with silt content and also significantly with field capacity, but either not at all or negatively with permanent wilting point. 4. Prediction equations for available water and field capacity were drown out from known soil properties, which can be used for each textural class.

• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.105-121
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• 2005

Most of the landslides triggered by intensive rainfall on natural slope occur serious damages of human beings and properties. There have been many landslides since 1991 in Gyeonggi province. The influential factors are rainfall, topography, geology and soil properties. There were 660 landslides occurred by intensive rainfall as much as 250mm at Yongin and Anseong area from Tuly 19th to luly 21st,1991 This study surveyed location, topography, geology, geometry of the landslide and rainfall at the area and analyzed occurrence characteristics of the landslides. Most of the landslides occurred on the soil layer above the bed rock. They showed changes of landslide types from translational slides at the head part to flow at the central part. The landslides have relatively small magnitude of which length is shorter than 50m. In order to identify characteristics of landslides dependent on soil conditions, geotechnical properties of soil were evaluated by laboratory tests using soil samples which were collected on slided area and not-slided area. Soil properties of the slided area show high percentage of coarse material such as gravel and sand. However, soil of the not-slided area is mainly composed of fine material such as silt and clay. Permeability coefficients of the slided area are higher than those of the not-slided area.

• Ocean and Polar Research
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• v.24 no.4
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• pp.345-357
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• 2002

Ecological characteristics on habitats and morphological features of the seagrass Zostera caulescens Miki in Korea were examined. The biogeographical distribution of Z. caulescens was confirmed in the south coast of the Korea. Zostera caulescens usually inhabits at the inner bay, where is sheltered from wave action and 3.0 to 6.5 m deep. The sediment in habitats is composed of very fine muddy sand or sandy mud. In morphology, Z. caulescens is easily distinguished from other species of the genus by the formation of vegetative canopy on the top of reproductive stems. The number of longitudinal ribs in testa was 24 revealed by scanning electron microscope (SEM) while the number of ribs in Z. marina has been often reported to be 16-20. Purplish anthocyanin spots were displayed on the surface when the testa was removed. We found that the size and shape of leaf epidermal cells in Z. caulescens were very different from those of Z. marina when the leaf cuticles were removed by maceration which could be useful characters for identifying Zostera species. The leaf of Z. caulescens displays two different casts of color when the fresh plant is closely observed. The margins of leaves appear brighter than the center of leaves due to the thickening by the development of paralleled venation in the middle of leaves. The comparison of two populations of Z. caulescens in Korea showed that they were considerably different in their shoot density and biomass. The shoot density and biomass at Gabae population was $367.3 m^{-2}\;and\;725.7g$ dry wt $m^P{-2}$ respectively, while those at Jukrim population were $112.5m^{-2}\;and\;392.0g\;dry\;wt\;m^{-2}$, respectively.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.56-60
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• 2000

A study was performed to determine the maintenance conditions of the earthworm, Lumbricus rubellus, for the acute toxicity test. To fine out climatic and soil conditions, the earthworms were maintained in artificial soil consisting of sand, clay mineral and peat at different levels of conditions for 14 days. Lumbricus rubellus led to an increase of biomass at temperature $22{\pm}2^{\circ}C$, soil pH $7.0{\pm}1$ and moisture 40%. And four fungicides were tested for acute toxicities to Lumbricus rubellus, according to the optimum condition. The test earthworms were exposed to each pesticide with various concentration gradients. After 14 days, the number of surviving earthworms and their weight alteration during the test period was determined. The 14-day $LC_{50}$ values for the Lumbricus rubellus, of carbendazim, benomyl, thiophanate-methyl and thiabendazole were determined to be 59, 53, 64 and 36 mg/ kg soil dry weight, respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.220-227
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• 2016

In this paper, polychlorinated biphenyls (PCBs) were measured in surface sediments collected three times (June, October, December, 2013), inside Jeju Harbor as major harbors of Jeju Island. The concentration of PCBs inside Jeju Harbor was in the range of 1.62~4.45 (mean) ng/g on a dry weight basis and the levels were very low. In the analysis of PCBS homologue patterns, high-chlorinated PCB congeners were dominant in surface sediments inside Jeju Harbor, indicating that their sources were originated from shipping activity. In the relationships between PCBs concentrations and particle size (mud, sand and gravel) in surface sediments, PCBs concentrations were higher in the sediments with higher mud content, indicating that higher PCBs were distributed with increasing sediments of fine gradules. The PCBs concentrations in surface sediments in this study were very low, compared with ER-L (effect range-low) and TEL (threshold effects level) among sediment quality guideleines (SQGs) applied in foreign countries, such as USA, Canada, and Australia, etc), indicating that their biological effects on the bottom organisms in marine environment were expected to be very low.

• Resources Recycling
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• v.22 no.2
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• pp.62-70
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• 2013

Electric arc furnace slag is made in ironworks during steel refining, it is been increasing chemical and physical resistibility using ageing method of unstable state of melting steel slag for using concrete's fine aggregates. Which is been changing stable molecular structure of aggregates, it restrains moving of ion and molecule. In Korea, KS F 4571 has been prepared for using the electric arc furnace slag to concrete aggregates. In this study, Electric arc furnace slag is used in the PMC(Polymer Modified Concrete) which is applied a bridge pavement of rehabilitation, largely. In that case, this study evaluates the structural safety about increasing the specific weight. The 4-type bridges(RC slab bridge, RC rigid-frame bridge, PSC Beam bridge, Steel box girder bridge) pavement's increasing the total dead load is in 1 ~ 2%. Design moments in a load combination are increased less then 2%. safety factor is decreased less than 3%. Therefore, the structural safety has no problem for applying the electric arc furnace slag within PMC in bridge.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.203-212
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• 2007

Mineral compositions of 89 Yellow Sea surface sediments collected at the second cruise in 2001, were determined using the high resolution X-ray diffractometer and Siroquant v.3.0 program. Yellow Sea surface sediments are composed of major minerals (quartz 57.8%, plagioclase 16.0% and alkali feldspar 10.0%), clay minerals, and calcite. Illite (8.7%) is the most abundant clay mineral, chlorite (2.6%) is the second, and kaolinite (0.6%) is few. however smectite is not detected. Quartz content is very high around the margin of the Yellow Sea, however is very low along the northwest to southeast direction extending from southeast of Sandong Peninsula to southwest of Jeju Island. It has similar distribution pattern with that of coarse sediment (sand). The coarse sediment, is mainly consisted of quartz, may be much supplied from the eastern part and southwestern part of the Yellow Sea. Illite distribution pattern is opposite to that of quartz. It is similar to those of clay and mud particles, therefore it can be suggested that fine sediment may be largely supplied from the northwestern part of the Yellow Sea. It is necessary to continue this kind of investigation, because it is difficult to interpret the sediment provenance of the Yellow Sea only from the result of this study.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.45-54
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• 1999

It is known from the previous study on the behavior of sharter single pile during simulated seaquake induced by the vertical component of earthquake that the compressive capacity and the soil plugging resistance of single open-ended pipe pile were completely degraded. But, the capacity of single open-ended pipe pile with greater penetration and the capacity of piles group with shorter penetration were expected to be stable after seaquake motion. In this study, first single pile, 2-pile or 4-pile groups with several simulated penetrations were driven into the calibration chamber with saturated fine medium sand and the compressive load test for each installed pile or pile groups was performed. Then, about 95% compressive load of the ultimate capacity was applied on the pile head during the simulated seaquake motion. Finally, to confirm the reduction of pile capacity during the simulated seaquake motion, the compressive load test for each single pile or pile groups after seaquake motion was performed. During the simulated seaquake, compressive capacities of single open-ended pipe pile and piles group installed in shallow sea were not decreased. But, the stability of open-ended pile installed in deep sea was depended on the pile penetration depth. So, single open-ended pile with greater penetration of 27 m was stable, and 2-pile and 4-pile groups with penetration more than 13m were stable. But, 2-pile groups with penetration of 7m was failed, and the compressive capacity of 4-pile groups with penetration of 7m was degraded about 15%.