• Economic and Environmental Geology
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• v.28 no.4
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• pp.351-367
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• 1995

The elemental geochemistry and oxygen isotopes of illite/smectite (I/S) have been studied in relationship to the mineralogical trend in the Reindeer D-27 well, Beaufort-Mackenzie Basin. The increase in concentrations of $K_2O$, Rb and rare earth elements (REE), the decrease in concentrations of tetrahedral elements such as Mg, Ti, Sc, Zn and Zr, and the increase in concentrations of tetrahedral elements such as Be and V can be related to I/S compositions that vary systematically with depth. Layer formulae of S- and I-layers are estimated as $[Al_{1.57}Fe_{.19}Mg_{.31}Ti_{.07}][Si_{3.84}Al_{.16}]O_{10}(OH)_2$ and $[Al_{1.84}Mg_{.16}][Si_{3.33}Al_{.67}]O_{10}(OH)_2$, respectively. The mobilization of REE appears to occur during illitization. The increase in concentrations of REE, especially La and Ce, with depth is probably linked to incorporation of ions with high valency (e.g. $V^{5+}$) in tetrahedral sites. The excess valency due to V is partly counter-balanced by ions with low valency (e.g. $Be^{2+}$) and, in turn, the local valency deficiency caused by $Be^{2+}$ could be compensated by high-charge interlayer cations such as REE (＋3). ${\delta}^{18}O$ values of I/S range from 2.91 to 15.72‰ (SMOW), and increase with depth, contrasting to trends observed in the Gulf Coast and elsewhere. The increase in ${\delta}^{18}O$ of I/S results from the rapid increase in ${\delta}^{18}O$ of pore water that overcomes the decrease in temperature-dependent fractionation values with increasing burial depth (${\delta}^{18}O_{pore\;water}>-d{\Delta}/_{I/S-water};\;d{\delta}^{18}O_{I/S}>0$). Calculated ${\delta}^{18}O$ values of pore water in equilibrium with I/S suggest that the original water was probably meteoric water. The stratification of pore water is postulated from the presence of an isotopically light interval, about 450m thick. The depth range of the isotopically light zone overlaps, but does not coincide with the interval of lowered I-content and $K_2O$ concentrations, suggesting that oxygens may have been exchanged independently of mineralogical and geochemical reactions.

• Korean Journal of Microbiology
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• v.52 no.2
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• pp.192-201
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• 2016

Recently, Psychrobacter sp. ArcL13 strain showing the extracellular lipase activity was isolated from the Chuckchi Sea of the Arctic Ocean. However, due to the low expression levels of the enzyme in the natural strain, the production of recombinant lipase is crucial for various applications. Identification of the gene for the enzyme is prerequisite for the production of the recombinant protein. Therefore, in the present study, a novel lipase gene (ArcL13-Lip) was isolated from Psychrobacter sp. ArcL13 strain by gene prospecting using PCR, and its complete nucleotide sequence was determined. Sequence analysis showed that ArcL13-Lip has high amino acid sequence similarity to lipases from bacteria of some Psychrobacter genus (84-90%) despite low nucleotide sequence similarity. The lipase gene was cloned into the bacterial expression plasmid and expressed in E. coli. SDS-PAGE analysis of the cells showed that ArcL13-Lip was expressed as inclusion bodies with a molecular mass of about 35 kDa. Refolding was achieved by diluting the unfolded protein into refolding buffers containing various additives, and the highest refolding efficiency was seen in the glucose-containing buffer. Refolded ArcL13-Lip showed high hydrolytic activity toward p-nitrophenyl caprylate and p-nitrophenyl decanoate among different p-nitrophenyl esters. Recombinant ArcL13-Lip displayed maximal activity at $40^{\circ}C$ and pH 8.0 with p-nitrophenyl caprylate as a substrate. Activity assays performed at various temperatures showed that ArcL13-Lip is a cold-active lipase with about 40% and 73% of enzymatic activity at $10^{\circ}C$ and $20^{\circ}C$, respectively, compared to its maximal activity at $40^{\circ}C$.

• Journal of the Mineralogical Society of Korea
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• v.32 no.1
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• pp.51-61
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• 2019

Clay minerals, a major component of mud volcano (MV) sediments, are expected to provide important information for characterizing mud volcano formation mechanisms, but clay minerals have rarely been studied. The purpose of this study is to investigate the characteristics of 420 MV and surrounding marine sediments. Clay minerals and grain size were analyzed for 8 box cores from 420 MV and Mackenzie Trough. The relative proportions of the four major clay minerals in the Mackenzie Trough are almost constant in the order of illite, chlorite, kaolinite, and smectite, regardless of the distance from the Mackenzie River. However, the grain size tends to become fining as they move away from the Mackenzie River. Comparing the clay mineral characteristics of river (Colville River, Kuparuk River, Sagavanirktok River, Canning River, Mackenzie River) sediments entering the Beaufort Sea in order to determine the origin of the Mackenzie Trough and 420 MV sediments, the sediments of the Mackenzie Trough are characterized mainly by the Mackenzie River with a low ratio of smectite/illite and a high ratio of kaolinite/chlorite. In 420 MV sediments, the contents of clay minerals decrease in the order of illite, kaolinite, chlorite, and smectite, and the grain size with depth is almost constant. The content of smectite and coarse sediments is about two times higher than the reference core. No river with higher kaolinite content than chlorite exists in the Beaufort Sea, and the ratio of smectite/illite to kaolinite/chlorite is different from the reference core such as the ratio of the Mackenzie River. Compared to the reference core, the high contents of coarse sediments and the constant grain size with depth might be attributed to the ejection by MV. The reference core is interpreted as originating from Mackenzie River, and sediment of 420 MV is interpreted as originating from eruption of MV.

• Journal of The Korean Association For Science Education
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• v.42 no.1
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• pp.19-32
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• 2022

The need for polar education was further emphasized, depending on the importance of the pole, which is the best place for climate change detection and prediction, and treasure trove of future technology and resources. Therefore, this study analyzed the general cognitive and affective characteristics of elementary school students' polar literacy, and in addition, analyzed the cognitive and affective characteristics according to the level of diversity about polar experience. The items developed for the study were revised through a pilot survey of 43 fifth graders. They consisted of questions about gender, polar experience, scientific literacy, polar knowledge, polar literacy skills, polar literacy beliefs, and polar literacy attitudes. The types of questions used are selectable, reliable, and Likert (4 points), for a total of 66 questions. The students who participated in the study were 323 fifth grade elementary students. The study found that students were more interested in the dramatic consequences of polar changes than the scientific causes and processes associated with it. This is confirmed through the fact that they are more interested in and familiar with polar creatures suffering from polar changes than understanding ice, which is the main feature of and the central mechanism of polar changes. Students also recognized the issue of polar climate change as a global issue other than their own. They believe that what happens in the Arctic and Antarctica will affect the whole world, but not significantly to himself and his community. The level of knowledge about polar region and the ability to analyze and infer were not significantly related to each other, and students with a higher level of diversity of experience about polar region had a better understanding of polar science and technology. In this research, it is meaningful to check the characteristics related to the students' polar region and to use it as a basic data to show the direction in which polar literacy education should proceed in the future.

• Journal of Plant Biology
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• v.38 no.3
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• pp.305-317
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• 1995

The bryophyte communities on the forest floor of the mixed coniferous, deciduous broad-leaf forest and the evergreen coniferous forest of cool temperate and subalpine zones in Chiri Mountains with the highest peak (Cheonwangbong 1915 m) in south-central part of the Korean Peninsula were investigated from the phytosociology viewpoint. As a result, five bryophyte communities were recognized, considering the species composition of vascular vegetation; A. Sasamorpha borealis-Abies koreana/Dicranum scoparium-Plagiothecium silvaticum community, B. Bosta minor-Abies koreana/Anomodon rugelii-Plagiomnium cuspidatum community, C. Abies koreana/Hylocomiopsis ovicarpa-Entodon rubicundus community, D. Abies koreana-Picea jezoensis/Hylocomiopsis ovicarpa-Thuidium kanedae community, E. Abies koreana-Pieea jezoensis/Hylocomium splendens-Pleurozium sehreberi community. Among these, the communities A, B, C and D were distributed in the mixed coniferous and deciduous broad-leaf forest of lower altitudes (1200 to 1700 m) and characterized by the elements of the cool temperate zone. They were confimled as synusies belonging to the Fraxino-Abietetum koreanae Song 1988. The community E was distributed in higher altitudes (1700 m to near the summit) and characterized by the species group of the holarctic elements, e.g. Hyloeomium splendens, Pleurozium sehreberi, Dieranum majus, etc. limited in subarctic; subalpine and arctic; alpine zones. The community E was confirmed as a synusie of the Abieti koreanae-Piceetum jezoensis Song 1991 belonging the Vaecinio-Pieeetea Br.-BI. 1939. Up to date many investigator have described the coniferous forest distibuted above 1200 m in Chiri mountauns as the forest vegetation of subalpine zone. However, from the results of the present study, the boundary of the mixed forest and the true subalpine coniferous forest was elucidated to be ca. 1700 m phytosociologically. Species richness was highest in the community E, and the other four communities showed a similar species richness. Among the species diversity indices, H' and D were high in the communities Band E, low in the communities A and C, and medium in the community D. The values of J' decreased with the increase in altitudes and the community E showed the lowest value. The result of Bray-Curtis ordination revealed that the diversity analysis and the division of the above two forest zones are justifiable. The taxa of the bryophyte communities were composed of 25 families, 46 genera, 73 species, 1 subspecies and 2 varieties.

• Journal of the Korean earth science society
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• v.42 no.2
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• pp.201-220
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• 2021

The objective of this study is to increase awareness and interest regarding polar science and thereby aid in establishing the concept and future direction of polar literacy. To analyze the current status, textbooks based on the common school curriculum pertaining to polar topics were reviewed. Six countries that actively conduct polar science, namely Korea, France, Japan, Germany, the United States, and the United Kingdom, were chosen. Subsequently, 402 cases in 110 science and social studies (geography) textbooks of these countries were analyzed through both quantitative and qualitative methods. Based on the obtained results, the importance of polar research in geoscience education and the need for spreading awareness regarding polar research as an indicator of global environmental changes were examined. It was found that the primary polar topics described in the textbooks are polar glaciers, polar volcanism, solid geophysics, polar infrastructure, and preservation of geological resources and heritage. This demonstrates that the polar region is a field of research with important clues to Earth's past, present, and future environments and is also a good teaching subject for geological education. However, an educational approach is needed for systematically laying emphasis on polar research. The implications of this study are manifold, such as the establishment of a cooperative system between polar scientists and educators, extraction of core concepts for polar literacy and content reconstruction, discovery of new polar topics associated with the curriculum, diversification of forms of presentation in textbooks, and development of an affective image that is based on correct cognitive understanding. Furthermore, through the continuance of polar topics in textbooks, students can improve their awareness regarding polar literacy and polar science culture, which in turn will serve as the driving force for sustainable polar research in the future.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.4
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• pp.74-85
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• 2020

Darangnon in Gachon Village, Namhae-gun, Gyeongsangnam-do, is the first designated environment among Korea's industrial-based historical and cultural sites and is still the only one that involves agricultural activities. Although the stonework, which is the infrastructure environment here, has limitations that inevitably lead to natural and artificial deformation due to its nature, there has been no research to consider the situation so far. As of the end of May 2020, this study investigated and analyzed the damage in the sub-area of the survey, which is approximately 30% of the scope of the designation of the scenic spot, from a quantitative and qualitative perspective. As a result of the study, the state of loss, which reveals the physical damage of the arctic rice paddy stone retaining wall in the environment under investigation, was particularly serious around the coast, in the northern area with high slopes, and near tourist information centers and parking lots. On the other hand, the qualitative aspect of the damage to the stonework was noticeable in the repair of heterogeneous materials on the stone retaining wall adjacent to the village and parking lot, and the landscape damage caused by the cladding of plants was found in an environment far away from the residence. In addition, natural environmental factors such as slopes, elevations, and soil showed a close relationship with the degree of physical damage of the stone retaining wall, the higher the slope, the higher the elevation, and the better the soil drainage, the greater the impact. These results suggest that humanities environmental factors such as cultivation activities and management entities have important factors in the physical damage and management of stone retaining wall. Therefore, it is deemed essential to find management measures with local residents along with improving the agricultural environment, such as securing agricultural water and soil improvement, for the preservation of tuna paddies and stone retaining wall in the future.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.303-312
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• 2023

The determination of the oxidation states of metal elements in manganese nodules sheds light on the understanding of the formation mechanism of nodules, providing insights into the paleo-environmental conditions such as the redox potential of the aqueous system. This study aims to reveal the oxidation states and chemical bonding of manganese in the natural polymetallic nodules, utilizing conventional X-ray photoelectron spectroscopy (XPS). Specifically, shallow manganese nodules from the Siberian Arctic Sea, effectively recording mineralogical variations, were used in this study. Detailed analysis of XPS Mn 2p spectra showed changes in the manganese oxidation state from the center to the outer parts of the nodules. The central part of the nodules showed a higher Mn⁴⁺ content, approximately 67.9%, while the outermost part showed about 63% of Mn⁴⁺ due to an increase in the Mn³⁺+Mn²⁺. The decrease in the Mn oxidation state with the growth is consistent with the previously reported mineralogical variations from todorokite to birnessite with growth. Additionally, the O 1s spectra presented a predominance of Mn-O-H bonds in the outer layers compared to the center, suggesting hydration by water in the layered manganates of outer layers. The results of this study demonstrate that XPS can be directly applied to understand changes in paleo-environmental conditions such as the redox states during the growth of manganese nodules. Finally, future studies using high-resolution synchrotron-based XPS experiments could achieve details in oxidation states of manganese and trace metal elements.

• Maritime Security
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• v.5 no.1
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• pp.1-53
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• 2022

One manifestation of the contemporary era of renewed great power competition has been the deepening relationship between China and Russia. Their strengthening military ties, notwithstanding their lack of a formal defense alliance, have been especially striking. Since China and Russia deploy two of the world's most powerful navies, their growing maritime cooperation has been one of the most significant international security developments of recent years. The Sino-Russian naval exercises, involving varying platforms and locations, have built on years of high-level personnel exchanges, large Russian weapons sales to China, the Sino-Russia Treaty of Friendship, and other forms of cooperation. Though the joint Sino-Russian naval drills began soon after Beijing and Moscow ended their Cold War confrontation, these exercises have become much more important during the last decade, essentially becoming a core pillar of their expanding defense partnership. China and Russia now conduct more naval exercises in more places and with more types of weapons systems than ever before. In the future, Chinese and Russian maritime drills will likely encompass new locations, capabilities, and partners-including possibly the Arctic, hypersonic delivery systems, and novel African, Asian, and Middle East partners-as well as continue such recent innovations as conducting joint naval patrols and combined arms maritime drills. China and Russia pursue several objectives through their bilateral naval cooperation. The Treaty of Good-Neighborliness and Friendly Cooperation Between the People's Republic of China and the Russian Federation lacks a mutual defense clause, but does provide for consultations about common threats. The naval exercises, which rehearse non-traditional along with traditional missions (e.g., counter-piracy and humanitarian relief as well as with high-end warfighting), provide a means to enhance their response to such mutual challenges through coordinated military activities. Though the exercises may not realize substantial interoperability gains regarding combat capabilities, the drills do highlight to foreign audiences the Sino-Russian capacity to project coordinated naval power globally. This messaging is important given the reliance of China and Russia on the world's oceans for trade and the two countries' maritime territorial disputes with other countries. The exercises can also improve their national military capabilities as well as help them learn more about the tactics, techniques, and procedures of each other. The rising Chinese Navy especially benefits from working with the Russian armed forces, which have more experience conducting maritime missions, particularly in combat operations involving multiple combat arms, than the People's Liberation Army (PLA). On the negative side, these exercises, by enhancing their combat capabilities, may make Chinese and Russian policymakers more willing to employ military force or run escalatory risks in confrontations with other states. All these impacts are amplified in Northeast Asia, where the Chinese and Russian navies conduct most of their joint exercises. Northeast Asia has become an area of intensifying maritime confrontations involving China and Russia against the United States and Japan, with South Korea situated uneasily between them. The growing ties between the Chinese and Russian navies have complicated South Korean-U.S. military planning, diverted resources from concentrating against North Korea, and worsened the regional security environment. Naval planners in the United States, South Korea, and Japan will increasingly need to consider scenarios involving both the Chinese and Russian navies. For example, South Korean and U.S. policymakers need to prepare for situations in which coordinated Chinese and Russian military aggression overtaxes the Pentagon, obligating the South Korean Navy to rapidly backfill for any U.S.-allied security gaps that arise on the Korean Peninsula. Potentially reinforcing Chinese and Russian naval support to North Korea in a maritime confrontation with South Korea and its allies would present another serious challenge. Building on the commitment of Japan and South Korea to strengthen security ties, future exercises involving Japan, South Korea, and the United States should expand to consider these potential contingencies.