• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.259-265
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• 2021

A diagnostic test for viral hemorrhagic septicemia virus (VHSV), which infects more than 80 species of freshwater and marine fish at home and abroad, causing mass mortality, was conducted to provide quantitative data on the amount of virus expression in various tissues of flounder in chronological order. The tissues were collected in chronological order after the intraperitoneal injection of 3.0E+07 tissue culture infective dose₅₀ (TCID₅₀) per 0.1mL per fish of VHSV to randomly selected flounder. As a result of relative quantification through real-time PCR, the highest levels of virus expression were found in the spleen, kidney, gill, and liver on day 5. This study proved that the spleen was an appropriate site for the final diagnosis of VHSV in the early stages of infection and will provide important information for the diagnosis of legal infectious diseases in Korea.

• Journal of the Korean earth science society
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• v.41 no.3
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• pp.222-237
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• 2020

A heavy (93 mm hr^-1) rainfall event accompanied by lightning occurred over Gangneung in the Yeongdong region of South Korea on August 6, 2018. This study investigated the underlying mechanism for the heavy rainfall event by using COMS satellite cloud products, surface- and upper-level weather charts, ECMWF reanalysis data, and radiosonde data. The COMS satellite cloud products showed rainfall exceeding 10 mm hr^-1, with the lowest cloud-top temperature of approximately -65℃ and high cloud optical thickness of approximately 20-25. The radiosonde data showed the existence of strong vertical wind shear between the upper and lower cloud layers. Furthermore, a strong inversion in the equivalent potential temperature was observed at a pressure altitude of 700 hPa. In addition, there was a highly developed cloud layer at a height of 13 km, corresponding with the vertical analysis of the ECMWF data. This demonstrated the increased atmospheric instability induced by the vertical differences in equivalent potential temperature in the Yeongdong region. Consequently, cold, dry air was trapped within relatively warm, humid air in the upper atmosphere over the East Sea and adjacent Yeongdong region. This caused unstable atmospheric conditions that led to rapidly developing convective clouds and heavy rainfall over Gangneung.

• Journal of the Korean Geographical Society
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• v.44 no.6
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• pp.691-705
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• 2009

Phytolith analysis was made on a 660cm core from Lake Gyeongpo in the East Sea of Korean Peninsula to clarify the environmental change including climate and agricultural characteristics during the Holocene. From the results of phytolith analysis, six phytoliths assemblage zone(PAZ) were recognized from the base to the surface. PAZ I around 5,000 yr BP suggests the transition from the warm and dry to the cool and wet climatic conditions. The climate of PAZ II(ca. 4,000-2,000 BP) was kept on warm, but repeated between dry and wet conditions. PAZ III(2,000~1,000 yr BP) suggests the expansion of agricultural activities under the warm and humid climatic conditions due to the significant phytoliths production of Paniceae and Oryza sativa. While PAZ IV(1,000~500 yr BP) indicates very cool and dry conditions, PAZ V and IV suggest the warm-dry and cool-humid climatic conditions, respectively. Similar to the results of pollen analysis in the lake, the agricultural activities were recognized by PAZ III around 2,000 yr BP from the results of phytolith analysis, and the rice cultivations such as Oryza sativa have been expanded since 2,000 yr BP or later.

• Journal of Life Science
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• v.21 no.2
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• pp.176-182
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• 2011

Deep seawater (DSW) generally refers to seawater at depths equal to or greater than 200 meters. DSW is rich in inorganic materials which have attracted attention for its various applications. In this study we investigated the effects of the DSW upwelled from the East Sea, offshore Yang Yang (KangWon-do, Korea), on the expression of ${\mu}$-opioid receptor (MOR) of cultured rat hippocampal neurons. Neurons were grown in a minimal essential medium containing 10% (v/v) fetal bovine serum and either 25% (v/v) distilled water, or hardness (H) 800, or H 1000 DSW. Cultures grown in the presence of DSW with H 800 and H 1000 exhibited robust MOR immunoreactive signals in both neurons and astrocytes. Interestingly, the increase in MOR immunoreactive signals was more dramatic in astrocytes than in neurons. Statistical analysis revealed that the relative intensities for MOR clusters increased approximately 4-fold in astrocytes cultured in H 800 and H 1000 media. These increases were statistically very significant (p<0.001). In contrast, the increase in intensities for MOR immunoreactive signals was relatively less dramatic in neurons, where only the increase in the H 1000 culture was statistically very significant (p<0.001). These results indicated that DSW promotes expression of MOR in both neurons and astrocytes, and more significantly in the latter.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.1
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• pp.37-46
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• 2016

This study describes the spatio-temporal distributions in phytoplankton community such as species composition, standing crops and dominant species from April to November 2008 in the Uljin Marine Ranching Area (UMRA). A total of 123 species of phytoplankton belonging to 67 genera was identified. In particular, diatoms and dinoflagellates were occupied more than 60.5% and 34.6% of total species, respectively. The annual dominant species were Thalassiosira sp., Pseudo-nitzschia pungens in spring, Leptocylindrus danicus, Guinardia striata in early summer, Cheatoceros cirvisetus, Ch. decipiens in early autumn and Skeletonema costatum -ls (like species), Pn. pungens in autumn. Phytoplankton cell density fluctuated with an annual mean of $48cells{\cdot}mL^{-1}$ between the lowest value of $1.8cells{\cdot}mL^{-1}$ in early autumn and the highest value of $240cells{\cdot}mL^{-1}$ in spring. According to the cluster analysis, the phytoplankton community of the UMRA was characterized by the nutrient supply from land side and water movement as current.

• Journal of fish pathology
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• v.30 no.2
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• pp.79-88
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• 2017

At the present, fish farms are suffering a lot of economic losses due to infectious diseases caused by various pathogens including aeromonad. Aeromonad is ubiquitous bacteria that causes infectious diseases. At least 26 species in the genus Aeromonas have been reported to cause fatal infections not only in salmonid fishes, but also in other freshwater and seawater fishes. Molecular techniques based on nucleic acid sequences of 16S rDNA and housekeeping genes can be used to identify the Aeromonas species. In this study, The genus Aeromonas was isolated from salmonid fishes of sixteen fish farms in Gangwon-Do, Korea and phylogenetically identified based on the sequences of 16S rDNA and housekeeping genes for Aeromonad, i.e. RNA polymerase sigma factor ${\sigma}^{70}$ (rpoD) or DNA gyrase subunit B (gyrB). Consequently, 96 strains were collected from Atlantic salmon (Salmo salar), coho salmon (Oncorhynchus kisutch), masou salmon (Oncorhynchus masou) and rainbow trout (Oncorhynchus mykiss), and 36 isolates were identified as the genus Aeromonas by 16S rDNA analysis. Thirty six Aeromonad isolates were further analysed based on rpoD or gyrB gene sequences and found Aeromonas salmonicida (24 isolates), A. sobria (10 isolates), A. media (1 isolates) and A. popoffii (1 isolates), indicating that A. salmonicida is a main infectious bacteria in Salmonid fishes in Gangwon-Do. It was also proved that the phylogenetic identification of Aeromonas species based on the sequences of housekeeping gene is more precise than the 16S rDNA sequence.

• Journal of Korean Society of Transportation
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• v.21 no.6
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• pp.7-15
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• 2003

China is expected to experience rapid increase in container traffic due to the joining to WTO and the fast economic growth. However, logistics-related infrastructure such as sea port is very poor and the capacity is lagging far behind the demand, resulting in transferring around 70% of import and export cargo volume at ports in adjoining countries such as Korea, Taiwan, Hong Kong and Japan. Recently, China announced a huge project of developing an offshore port consisting of 52 berths, 30km away from Shanghai with a connecting bridge. As such plan seems to have a significant impact on the port of Pusan which tries to be a Hub port in Far East Asia, we need to scrutinize the plan. This paper, therefore, tries to examine Shanghai New Port Plan, to evaluate the feasibility and potential competitiveness, and to analyze the impact on Pusan port. For this, we review the situation of major container ports in China and the flow pattern of container traffic to and from Pusan port. We then examine the feasibility of the proposed offshore port with respect to demand and supply for container terminal, weather condition, hinterland connection and resource of investment.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.353-361
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• 2013

An in situ mesocosm experiment was designed to investigate how exposure to ocean acidification by increased carbon dioxide affected the growth of juvenile oliver flounder (Paralichthys olivaceus). A total of 447 individuals were reared in the mesocosm experimental devices deployed at sandy-muddy bottom in the southern coast of East Sea for 43 days and divided into two groups: treatment group (223 individuals, $6.32{\pm}0.75$ cm, high-$CO_2$ environment) and control group (224 individuals, $6.34{\pm}0.84$ cm, natural $CO_2$ environment). The average values of pH and $CO_2$ concentration in the treatment device were $7.63{\pm}0.13$ and $1660{\pm}540$ ${\mu}atm$, respectively, while those in the control device were $8.07{\pm}0.05$ and $514{\pm}65$ ${\mu}atm$, respectively. There was no significant difference in mortality rate between treatment and control group, and the mortalities in two groups gradually decreased during the study period. But, the increase of size and weight of juvenile oliver flounder was higher in control group than treatment group, i.e., weight gain or growth rate was higher in control group. These results suggested that high $CO_2$ environments could have a significant negative influence on the early growth of juvenile oliver flounder.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.113-126
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• 2022

The tectonic history of the Chukchi Abyssal Plain in the Amerasia Basin, Arctic Ocean, has not been fully explored due to the harsh conditions of sea ice preventing detailed observation. Existing models of the tectonic history of the region provide contrasting interpretation of the timing of formation of the crust (Mesozoic to Cenozoic), crust type (from hyper-extended continental crust to oceanic crust), and formation process (from parallel/fan-shaped rifting to transformation faulting). To help determine the age of the oceanic crust, the geothermal gradient was measured at three stations in the south of abyssal plain at depth of 2,160-2,250 m below sea level. Heat flow measurement stations were located perpendicular to the spreading axis over a 40 km-long transect. In-situ thermal conductivity measurement, corrected by the laboratory test, gave observed marine heat flows of 55 to 61 mW/m². All measurements were taken during Arctic expeditions in 2018 (ARA09C expedition) and 2021 (ARA12C expedition) by the Korean ice-breaking research vessel (IBRV) Araon. Given the assumption of oceanic crust, the results correspond to formation in the Late Cretaceous (Mesozoic). The inferred age supports the hypothesis of formation activated by the opening of the Makarov Basin during the Late Mesozoic-Cenozoic. This would make it contemporaneous with rifting of the Chukchi Border Land immediately east of the abyssal plain. The heat flow data indicate the base of the gas hydrate stability zone is located 332-367 m below the seafloor, this will help to identify the gas hydrate-related bottom simulating reflector in the future seismic survey, as already identified on the Chukchi Plateau. Further geophysical surveys, including heat flow measurements, are required to increase our understanding of the formation process and thermal mantle structure of the abyssal plain.

• Strategy21
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• s.33
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• pp.5-36
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• 2014

This article aims to analyze the diplomatic challenges currently facing China as well as the foreign policy the Xi Jinping administration is adopting to address them. With these purposes in mind, it will look into three areas: first, diplomatic tasks confronting the Xi leadership; second, foreign policy that the Xi administration has implemented since the 18th Party Congress in 2012; and third, the prospects for China's foreign policy under the Xi leadership. As the Xi Jinping administration entered into office, it has encountered two major diplomatic challenges. One is the searching for a new foreign policy, and the other the restructuring of the existing foreign affairs and national security systems. The Xi administration, during its first year in office, has responded actively to tackle these issues. To begin with, it has attempted to make some adjustments on foreign policy while maintaining the Deng Xiaoping line of foreign policy. One of these modifications is placing emphasis on national "core interest," as illustrated by changes in guideline for maritime conflicts, pushing for building maritime power, and proclamation of Air Defense Identification Zone in the East China Sea. Second is the decision on the new guideline for peripheral diplomacy. That is, the administration regarded creating peaceful and stable environments to realize "Chinese Dream" as an important goal of foreign policy, and proposed such new guiding ideology as "familiarity, integrity, benefit, and accommodation." In additoin, the Xi administration restructured the existing foreign affairs and national security systems. Establishing the Central State Security Committee and the Internet Leading Small Group (LSG) are cases in point. As comprehensive organizations for policy coordination that encompass party, government, and military, the two LSGs are in charge of enacting related policies and fine-tuning policy implementation, based upon leadership consisting of chiefs of each relevant organs. Moreover, since Xi himself became the chief of these two newly-found organs, the conditions under which these LSGs could demonstrate unified leadership and adjusting role in its implementation of military, diplomatic, and security policies were developed. The future Chinese diplomacy will be characterized with three main trends. First, peripheral diplomacy will be reinforced. The peripheral diplomacy has become far more important since the Work Conference on Peripheral Diplomacy in October 2013. Second, economic diplomacy will be strengthened with an eye on reducing the "China Threat Theory," which still exists in Asia. Third, the policies to isolate the Philippines and Japan will continue in regard to maritime disputes. All in all, Chinese diplomacy in the Xi Jinping era is likely to feature practical diplomacy which combines both hard and soft approaches to best realize Chinese national interest.