• Journal of the Korean Society of Groundwater Environment
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• v.6 no.3
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• pp.133-139
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• 1999

The geostatistical method Kriging is used to estimate the areal distributions of the depth to the water table and the altitude of the water table measured from the sea level. A northern part of the city of Pohang, Kyeong-Buk, Korea has been chosen and the digital map of the area with 1:5,000 scale from the National Geographic Information System (NGIS) project by National Geographic Institute has bun used to reproduce the ground surface distribution. The water table depth appears to be in the range between 7 m and 9.5 m except a few localities where mountain tops exist and the use of groundwater for agicultural purposes is believed to be heavy. The overall distribution of the water table altitude shows a monotonic gradual decrease from the west to the east (seaward direction from the inland) and to the south with maximum rate approximately at 90 m over 6 km in horizontal distance and indicates that the groundwater is moving several meters per day there.

• Journal of Marine Bioscience and Biotechnology
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• v.16 no.1
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• pp.1-18
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• 2024

Coastal dunes must be conserved. Their native halophytes support coastal geography while their symbiotic microorganisms help vegetation thrive. The Goraebul coast has the largest, well-conserved dune system on the East Sea of the Korean Peninsula due to a climax mixed halophyte (C. soldanella, C. kobomugi, and E. mollis) vegetation support. This study identified rhizobacteria and their diversity in mixed halophyte communities unique to Goraebul. Five phyla, 12 genera, and 21 species were identified based on 16S rDNA sequences from 65 isolates. The phylum Bacillota, class Bacillota, order Bacillales, and family Bacillaceae were identified, with Bacillus as the dominant genus (46.15%). The richness and Shannon's diversity were higher at the species than at the genus level due to the dominance of Bacillus; however, various Bacillus species (7) were identified. Therefore, the climax mixed vegetation adapted to the Goraebul coast may exert natural selection pressure in favor of the common characteristics of Bacillus. However, despite this advantage, the Shannon equitability (0.86), Simpson (0.08), and Shannon diversity (2.79) indexes indicate a stable rhizosphere cluster and the climax mixed vegetation is affected by symbiotic relationships between healthy rhizosphere microbiota.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.2
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• pp.33-40
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• 2023

Wave overtopping rate is one of the most important design parameters for coastal structures. In this study, the physical model tests for measuring the wave overtopping have been conducted with the foreshore slope in front of the seawall. The bottom seabed for the coastal road area was fabricated at the wave flume for two areas in the East sea areas. The wave overtopping rate was measured for various water depths and wave conditions in each coastal area. In particular, the impulsive wave conditions were compared with the previous research and the similar trends of wave overtopping was observed. It could be known that the effect of foreshore slope was significant and should be concerned for applying theses formula like EurOtop.

• Economic and Environmental Geology
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• v.39 no.3 s.178
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• pp.235-253
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• 2006

We interpreted marine seismic profiles in conjunction with swath bathymetric and magnetic data to investigate rifting to breakup processes at the Korean margin leading to the separation of the Japan Arc. The Korean margin is rimmed by fundamental elements of rift architecture comprizing a seaward succession of a rift basin and an uplifted rift flank passing into the slope, typical of a passive continental margin. In the northern part, rifting occurred in the Korea Plateau, a continental fragment extended and partially segmented from the Korean Peninsula, that provided a relatively broader zone of extension resulting in a number of rifts. Two distinguished rift basins (Onnuri and Bandal Basins) in the Korea Plateau we bounded by major synthetic and smaller antithetic faults, creating wide and symmetric profiles. The large-offset border fault zones of these basins have convex dip slopes and demonstrate a zig-zag arrangement along strike. In contrast, the southern margin is engraved along its length with a single narrow rift basin (Hupo Basin) that is an elongated asymmetric half-graben. Rifting at the Korean margin was primarily controlled by normal faulting resulting from extension in the west and southeast directions orthogonal to the inferred line of breakup along the base of the slope rather than strike-slip deformation. Although rifting involved no significant volcanism, the inception of sea floor spreading documents a pronounced volcanic phase which seems to reflect slab-induced asthenospheric upwelling as well as rift-induced convection particularly in the narrow southern margin. We suggest that structural and igneous evolution of the Korean margin can be explained by the processes occurring at the passive continental margin with magmatism intensified by asthenospheric upwelling in a back-arc setting.

• Journal of Animal Environmental Science
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• v.6 no.3
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• pp.141-151
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• 2000

Over-grown seaweeds in Donghae(east sea of Korea peninsula) may impedes ocean environment, however, they can be a good nutrient resources for poultry feeds if they are utilized properly. In this study, seaweeds powder were tested for laying hens\` ration to investigate the effects on egg production rate, egg quality and calcium phosphorus excretion. One hundred 65wks-old brown layers were fed for 5 weeks alotted with seaweeds powder addition to experimental diet by 0(control), 0.5, 1.0 and 2.0%, respectively, and obtained following results; 1. Seaweeds proved a mid-protein low-energy feed resources with planty of K, Na, Ca, Mg, Sr and Fe. 2. Seaweeds addition by 0.5% and 1.0% improved egg production rate and egg-mass output markedly(p<0.05) than control. Seaweeds addition did not alter cholesterol level of yolk and yolk index, however egg shell thickness showed increasing trend by increasing seaweeds addition level. 3. Protein absorption and digestibility in seaweed addition treatments were significantly higher(p<0.05) than control group and protein contents of excreta in 0.5% and 1.0% treatments were reduced(p<0.05), which suggests effective protein metabolism for egg production. Increasing seaweeds addition reduces Ca and P contents in rectum and excreta, suggesting Ca and P utilization improvement in laying hens and lessening soil pollution. 4. In conclusion, seaweeds addition in layers' diet by 1.0% level improves egg-mass production and might be egg quality by increasing metabolism of protein, calcium and phosphorus.

• Maritime Security
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• v.3 no.1
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• pp.1-44
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• 2021

China's new Maritime Policy Law (MPL) purports to regulate the duties of China's maritime police agencies, including the China Coast Guard, and safeguard China's sovereignty, security, and rights and interest. The MPL has potentially far-reaching application, as China claims extensive maritime areas off its mainland and in the South China Sea. This expansive application of maritime law enforcement jurisdiction is problematic given that most of China's maritime claims are inconsistent with international law. To the extent that the MPL purports to assert jurisdiction over foreign flagged vessels in disputed areas or on the high seas, it contravenes international law. Numerous provisions of the MPL regarding the use of force are also inconsistent with international rules and standards governing the use of maritime law enforcement jurisdiction, as well as the UN Charter's prohibition on the threat or use of force against the territorial integrity or political independence of any state. China could use the MPL as a subterfuge to advance its illegal territorial and maritime claims in the South and East China Seas and interfere with coastal State resource rights in their respective exclusive economic zone.

• Microbiology and Biotechnology Letters
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• v.45 no.3
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• pp.243-249
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• 2017

An agar-degrading bacterium, designated as the GNUM08123 strain, was isolated from samples of red algae collected from the Yongil Bay near East Sea, Korea. The isolated GNUM08123 strain was gram-negative, aerobic, motile, and beige-pigmented, with $C_{16:0}$ (25.9%) and summed feature 3 (comprising $C_{16:1}{\omega}7c/iso-C_{15:0}2-OH$, 34.4%) as its major cellular fatty acids. A similarity search based on the 16S rRNA gene sequence revealed that it belonged to class Gammaproteobacteria and shared 97.7% similarity with the type strain Vibrio chagasii $R-3712^T$. The DNA G+C content of strain $GNUM08123^T$ was 46.9 mol%. The major isoprenoid quinone was ubiquinone-8. The results of DNA-DNA relatedness and 16S rRNA sequence similarity analyses, in addition to its phenotypic and chemotaxonomic characteristics, suggest that strain GNUM08123 is a novel species within genus Vibrio, designated as Vibrio sp. GNUM08123. Agarase production by strain GNUM08123 was induced by agar and sucrose, but was repressed probably owing to carbon catabolite repression by glucose and maltose.

• Geophysics and Geophysical Exploration
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• v.13 no.3
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• pp.295-300
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• 2010

Recently, many tsunamis triggered by impulsive undersea ground motions occurred in subduction zones around the Pacific Ocean area including the East Sea surrounded by Korea, Japan and Russia. The wave height of a tsunami may be in the order of several meters, while the wavelength can be up to 1,000 km in the ocean, where the average water depth is about 4 km. A tsunami could cause a severe coastal flooding and property damage not only at neighboring countries but also at distant countries. A fundamental and economic way to mitigate unusual tsunami attacks is to construct tsunami hazard maps along coastal areas vulnerable to tsunami flooding. These maps should be developed based on the historical tsunami events and projected scenarios. The map could be used to make evacuation plans in the event of a real tsunami assault.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.483-488
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• 2015

We studied oocyte steroidogenesis in the blackfin flounder Glyptocephalus stelleri as a region-specific species, in the East Sea of Korea during the spawning season. Maturing oocytes (0.76, 0.82, 0.88, and 0.91 mm in oocyte diameter) were incubated in vitro in the presence of [$^3H$] $17{\alpha}$-hydroxyprogesterone ($[^3H]17{\alpha}$-OHP) as a precursor. Steroid metabolites were extracted from the incubated medium and oocytes, and the extracts were separated and identified by thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and gas chromatographymass spectrometry (GC/MS). The major metabolites produced from $[^3H]17{\alpha}$-OHP were androgens [androstenedione (A4) and testosterone (T)] and estrogens [$17{\beta}$-estradiol (E2) and estrone (E1)] and progestins [$17{\alpha},20{\alpha}$-dihydroxy-4-pregen-3-one ($17{\alpha}20{\alpha}P$) and $17{\alpha}20{\beta}$-dihydroxy-4-pregnen-3-one ($17{\alpha}20{\beta}P$)] in maturing oocytes. The metabolic rate of $17{\alpha}20{\beta}$ was elevated (29.04%) in oocytes measuring 0.88 mm (nucleus migration stage following the induction of germinal vesicle breakdown), but was very low in oocytes measuring 0.76, 0.82, and 0.91 mm (0.42, 0.67, and 2.62%, respectively). From these results, we suggest that $17{\alpha}20{\beta}P$ acts as a maturation-inducing steroid in the blackfin flounder.

• Economic and Environmental Geology
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• v.38 no.3 s.172
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• pp.299-304
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• 2005

Geoid undulation and gravity anomaly were calculated from GRACE satellite data on the eastern Asia including Korean peninsula. Geoid undulation varies from -60m in the China to 60m toward the Pacific Ocean across the Korean Peninsula. Calculated gravity anomalies are in the range of -60 and 60 mgal except the subduction zone showing -100 mgal. High positive values are observed at Mt. Baekdu, Kaema highland and Taebaek mountains, and low values at Ulleung, Japan and Yamato basins in the East sea. We removed regional components below the spherical harmonic degree of 10 from gravity anomaly to get the residual anomaly for crust components. Residual gravity anomaly shows high anomalies at the northern mountainous area and Kyungsang basin in the Korean Peninsula. And low anomalies appears at the western Korea bay basin, Kunsan basin, Cheju basin, and Ulleung basin in the marine. Anomalies separated by the spherical harmonic degree as well as the residual anomalies are useful for the study of large crustal structure about geologic scale and depth distribution and for the survey of natural resources.