• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.171-180
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• 2009

Based on the constituent analysis of sediments near Dok Island, the origin and sedimentary facies were Investigated. The sediments are mainly from originated from volcanic and volcaniclastic rock fragments derived from Dok Island and carbonate sediments formed by a variety of shallow-dwelling organisms that secreted calcareous skeletons. Carbonate producers include mollusks (bivalves and gastropods), encrusting & branching bryozoans, encrusting & segmented red algae, worm tubes, barnacles, diatoms, sponge spicules and echinoderm fragments. The distribution and relative amount of these constituents are basically dependent upon water depth and grain size even though local variations can be observed within the same depth interval. Five sedimentary facies can be divided: nearshore facies (<20 m), neritic facies ($20{\sim}100m$), upper transitional facies ($100{\sim}200m$), lower transitional facies ($200{\sim}700m$), and hemipelagic facies (>700 m). The sediments that were sampled below the water depth of 2,000 m still contain a significant amount of carbonates (ca. $10{\sim}20%$), implying that the carbonate compensation depth in the East Sea may well exceed this water depth.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.185-204
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• 2024

This study was conducted for evaluation the geological, physical, and chemical properties of domestic sand by analyzing about 4,800 quality data of natural sand from river and land area surveyed until 2023 through the aggregate resource survey conducted by the Ministry of Land, Infrastructure and Transport. The average depth of the Quaternary unconsolidated sedimentary layer in Korea, which includes a sand layer, is about 10m (maximum depth 66m). The thickness of the sand layer within the sedimentary layer is most dominant in the range of 0.5m to 4.0m. This accounts for about 70% of the entire sand layer. In the sand layer, the ratio of sand, gravel, and clay is 60:20:10. Regardless of the provenance or geology, the sand is mainly composed of quartz, plagioclase, and K-feldspar, and the minor minerals are muscovite, biotite, chlorite, magnetite, epidote. The sand includes in 45~75% of quartz, 5~20% of plagioclase and K-feldspar, each other. And other minor minerals are included in 10%. The average grain size of sand is 0.5mm to 1.0mm, which accounts for 44% of sand samples. The water absorption rate and soundness are estimated to be suitable for aggregate quality standard in almost all sand, and the absolute dry density is suitable for 66%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.297-303
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• 2024

In this study, KTN heterolayer thin films were fabricated by alternately stacking films of K(Ta_0.70Nb_0.30)O₃ and K(Ta_0.55Nb_0.45)O₃ synthesized using the sol-gel method. The sintering temperature and time were 750℃ and 1 hour, respectively. All specimens exhibited a polycrystalline pseudo-cubic crystal structure, with a lattice constant of approximately 0.398 nm. The average grain size was around 130~150 nm, indicating relatively uniform sizes regardless of the number of coatings. The average thickness of a single-coated film was approximately 70 nm. The phase transition temperature of the KTN heterolayer films was found to be approximately 8~12℃. Moreover, the 6-coated KTN heterolayer film displayed an excellent dielectric constant of about 11,000. As the number of coatings increased, and consequently the film thickness, the remanent polarization increased, while the coercive field decreased. The 6-coated KTN heterolayer film exhibited a remanent polarization and coercive field of 11.4 μC/cm² and 69.3 kV/cm at room temperature, respectively. ΔT showed the highest value at a temperature slightly above the Curie temperature, and for the 6-coated KTN heterolayer film, the ΔT and ΔT/ΔE were approximately 1.93 K and 0.128×10^-6 K·m/V around 40℃, respectively.

• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.223-228
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• 2010

High-frequency bottom loss measurements for grazing angle of $82^{\circ}$ in frequency range 17-40 kHz were made in Jinhae bay in the southern part of Korea. Observations of bottom loss showed the strong variation as a function of frequency, which were compared to the predicted values using two-layered sediment reflection model. The geoacoustic parameters including sound speed, density and attenuation coefficient for the second sediment layer were predicted from the empirical relations with the mean grain size obtained from sediment core analysis. The geoacoustic parameters for the surficial sediment layer were inverted using Monte Carlo inversion algorithm. A sensitivity study for the geoacoustic parameters showed that the thickness of surficial sediment layer was most sensitive to the variation of the bottom loss.

• The Korean Journal of Quaternary Research
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• v.34 no.1
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• pp.15-30
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• 2024

Typhoon effects on macrotide open-coast intertidal sediments were investigated in the Gochang Gwangseungri sandy intertidal flat on the Korean western coast. Variations in the surface sediment texture, accumulation, and sedimentary facies were observed before and after the Typhoon Kompasu in 2010. The typhoon Kompasu landed on the southwestern coast of the Korean Peninsula and passed inland between September 1st and 2nd, 2010, respectively. Surface sediments and their accumulation before and after the typhoon were sampled and measured at intervals of 30 m along a survey line on the Gwangseungri intertidal flat. The intertidal areas were divided into high, middle, and lower tidal zones based on the mean high-wate level, mean sea level, and mean low-water level, respectively. The surface sediments of each tidal zone show rare variations in grain size and sorting of sediment texture before and after the typhoon Kompasu, whereas negative skewness values increased in the middle and lower tidal zones after the typhoon rather than before the typhoon. Surface accumulation represents deposition in the upper and middle tidal zone and erosion in the lower tidal zones after the typhoon. The accumulation decreased from the high to the lower tidal zones.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.2
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• pp.164-168
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• 2024

(La_0.7Sr_0.3)(Mn_1-xFe_x)O₃ (LSMFO) (x = 0.03, 0.06, 0.09, 0.12) precursor solution are prepared by sol-gel method. LSMFO thin films are fabricated by the spin-coating method on Pt/Ti/SiO₂/Si substrate, and the sintering temperature and time are 800℃ and 1 hr, respectively. The average thickness of the 6-times coated LSMFO films is about 181 to 190 nm and average grain size is about 18 to 20 nm. As the amount of Fe added in the LSMFO thin film increased, the resistivity decreased, and the TCR and B_25/65-value increased. Electrical resistivity, TCR and B_25/65-value of the (La_0.7Sr_0.3)(Mn_0.88Fe_0.12)O₃ thin film are 0.0136 mΩ-cm, 0.358%/℃, and 328 K at room temperature, respectively. The resistivity properties of LSMFO thin films matched well with Mott's VRH model.

• 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.

• Korean Journal of Plant Resources
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• v.15 no.3
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• pp.177-187
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• 2002

In our experiment, selected mutants were used which showed not only the phenotype of a specific unpolished rice but also phenotypes of EM 40, LO 1050, and TAL 214. Reciprocal crosses between the mutants were conducted to select strains which would have more quantity of lipids than before. The constitution of fatty acid was also tested to figure out nutritional aspects of the mutants. In the crossing between EM 40 mutants and mutants (LO 1050) having a thick aleurone layer, the expression of EM 40 mutants has no relation with the thickness of the aleurone layer. And the lipid content of new F$_2$ strains through the crossing is 4.15 ％. The lipid content is larger than those of the parents including Kinmaze and in other crossings of this experiment. This is attributed to the fact that the new F$_2$ strains are the products of the crossing between genes responsible for the size of buds, where lipid is accumulated, and genes accountable for the thickness of the aleurone layer. In the crossing between EM 40 mutants and TAL 214 mutants, lipid content of the new F$_2$ strains is 3.8 ％, higher than 2.92 ％ of TAL 214 mutants. But the degree of lipid increase is smaller than in two other crossings. This is probably because genes expressing the phenotypes of TAL 214 affect the size of EM 40, which gets smaller. The aleurone layer of the new F$_2$ strains is 12 $\mu\textrm{m}$ thicker than the layer of TAL 214 mutants, but 6 $\mu\textrm{m}$ thinner than that of parents (LO 1050) having a thick aleurone layer. This seems to be affected by the size of a microscope. The phenotype of the new F$_2$ strains appears to be similar to that of TAL 214. The lipid content of the new F$_2$ strains is 3.85 ％, larger than 2.92 ％ of TAL 214 and 3.01 % of LO 1050. The increase may be due to the aleurone layer of LO 1050. And the size of the bud of the unpolished rice, though it is not big enough like that of LO 1050, seems to be affected by the accumulation of genes in the thick aleurone layer. The accumulation may contribute to the increase in the content of lipid. When it comes to the constitution of fatty acid, there is little difference between parents like Kinmaze and the new F$_2$ strains. But oleic acid increases while linoleic acid decreases. And the decrease in the linolenic acid seems to contribute to the increase in lipid content. This fact also raises the possibility that genes accountable for specific phenotypes could change the quality of rice if the genes are accumulated. Now, experiments on strains which have large lipid content in EM 40 type 1(ge-1, 3.68 ％), EM type 2(ge-2, 2.91 ％), thick aleurone layer(4.63 ％), and starch layer(3.44 ％) are under way to figure out the effects of gene accumulation. These experiments are likely to present the ways for increasing the lipid content.

• Korean Journal of Agricultural Science
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• v.12 no.2
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• pp.166-173
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• 1985

The multiple ear and tiller line (MET), which was selected from a local maize collection and has been selected for earliness by selfing for five generations, was compared its plant characteristics with four U.S. leading hybrids. 1. The general plant growth was a little retarded by poor soil fertility and structure. 2. The fresh weight of the MET line was about 97.8% of the U.S. check varieties. 3. The dry weight of the MET line was also about 94.5% of the check U.S. hybrids (1,695 kg / 10a.). 4. The tillering and eating habits of the MET line had contributed toward increasing fresh and dry weight of the MET line. 5. The average plant height of the MET line was much less than those of the check varieties, due to the selfing depression manifested by the MET line, (234.7cm. of the MET vs 250.7cm. of the check) 6. Apparent differences of disease resistance was observed among varieties studied. The degree of plants infected with the black stripe mosaic virus was over 20% for the check U.S. hybrids, while less than 5% of the MET line was infected with the disease. 7. The grain yield per 10 a of the MET line was far below the check hybrids due to the inbreeding depression of the MET line. However, the kernel number per unit area of the MET line with small size kernel was much greater than that of the check hybrids. The 100 kernel weight of the MET line was around 10 grams. 8. The average fresh and dry matter weight of the three ($sorghum{\times}sudan$ grass) varieties was very much alike with those of the MET line. 9. In conclusion, the use of the MET line for silage production may have dual adventages because of its low seed price and of its small size kernels, which may reduce the amount of seeds required for planting in an unit area.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.1
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• pp.170-176
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• 2002

The objective of this study was to investigate the current status of calcium fortification in processed foods for obtaining basic data on nutrition fortification policy and nutrition labeling, Surveyed samples were the products fortified wish calcium among processed products sold in department store and large mart in Seoul from Aug. 1998 to Aug. 1999. But supplementary health food or special nutritious food and weaning food and infant formula were excluded from them. We examined the kinds and numbers of added nutrients except calcium and the amounts of calcium per 100 g product and nutrient labeling of calcium-fortified foods. Surveyed products were 81 foods and they were grouped in grain products, milk and milk products, processed meat and fishes, ramyuns, retort pouch foods, fruit juice and drinks. and others. Calcium fortification was found in wide food groups, especially in snack foods and carbonated beverages. In relation to surveyed products, most of them were fortified with only calcium. The number of added nutrients in the product were relatively various in comparison with each food groups. In addition to calcium, the most frequently added nutrient was DHA, and were followed vitamin, mineral, oligosacchride, fiber, etc. This result showed that the kind(s) and the number(s) of nutrient added to product did not consider nutrition balance of calcium-fortified foods. Units of calcium content were decided by companies, therefore consumers confused labelled content with mouth dose of calcium and the comparison of the amounts added calcium among products was difficult. The amounts of calcium in products were from 16.4 to 1226 mg Per 100 and from 2.5 to 27.6% RDA (recommended daily allowance) per serving size. The amounts of calcium in many products were less than 10% RDA per serving size, whole appraisal about fortified content was needed. And for nutrient labeling on calcium, they used various term whether it is approved by law or not.