• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.43-47
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• 2011

Korea has seasonal weathers which result in the frosting of soil in winter times, and the thawing of soil in spring. These climate characteristics result in the damaging of pavements, due to the repeated freezing and thawing of road pavements during winter and spring. In order to reduce these pavement damages, anti-frost heave layers are being specially installed, however it is being applied based on foreign researches, and therefore result in the waste of national budget. With this study, a database system was constructed for effective management and monitoring of measured temperatures and function data of 2 meters below the embankment, cut slope, and the cutting-embankment boundary, which are 15 regions picked by the frost index diagram. As the study result, an effective storage and management-purpose database was established for easy data searching and downloading for the pavement design engineers.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.89-89
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• 2023

인간 활동에 의해 발생한 전 지구적 기후변화는 다양한 분야에 영향을 미치고 있다. 특히, 군락을 기반으로 서식하는 동식물은 기후변화에 가장 취약하며, 대부분의 군락 위치가 북상하거나 멸종 위기에 처해있다. 2022년에 발표된 IPCC(Intergovernmental Panel on Climate Change) 보고서는 섭씨 5도 이상 상승하면 생물군의 60%가 멸종될 것이라고 보고하였으며, 고위도와 고도로 이동하여 봄철 식물 성장이 과거보다 더욱 가속화 될 것으로 예측하였다. 따라서, 온실가스 농도에 따른 전 지구적 기후변화 분석은 다양한 분야에서 지속가능한 완화 및 적응 정책을 결정하는데 필요하다. 본 연구는 SSP2-4.5와 SSP5-8.5를 이용하여 Koppen-Geiger의 기후대 분류에 따른 전 지구 규모(아시아, 유럽, 남아메리카, 북아메리카, 오세아니아, 아프리카)의 과거 및 미래 기후대에 대한 변화를 분석하였다. 과거 기간의 기후대를 추정하기 위해 25개 CMIP6(Coupled Model Intercomparison Project 6) GCM(General circulation model)의 월 단위 강수량과 표면 온도를 사용하였으며 6개의 기간으로 구분하여 기후대 변화를 비교하였다. 더 나아가, 미래 기후대를 예측하기 위해 SSP(Shared Socioeconomic Pathways)2-4.5와 SSP5-8.5의 미래 기후변수를 사용하였으며, 전망 기간을 7개로 구분하여 전망 기간의 기후대를 변화를 비교하였다. 본 연구의 결과로는 온실가스 농도가 높은 시나리오에서는 북아메리카, 아시아, 유럽의 툰드라와 영구동토층이 가파르게 감소하였으며, 온대 기후 중 습한 아열대 기후대의 면적이 급속도로 증가하였다. 더 나아가, 남아메리카의 경우 대륙성 기후대가 지속적으로 감소하는 반면에 열대 우림 기후대는 증가한다. 오세아니아의 미래 기후대는 몬순의 영향을 받는 아열대 기후대가 증가하고 열대 우림은 증가할 것으로 예측하였다.

• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.71-80
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• 2010

Korea is considered to be a seasonal frozen soil area that thaws in the spring, and freezes in winter. In the current design codes for anti-freezing layer, the thickness of anti-freezing layer is calculated by the depth frozen due to the temperature condition. Therefore, there is a tendency of over-design and applying uniform thickness without the consideration of thermal stability, bearing capacity and frost susceptibility of materials. So, it is essential to study the structural appropriateness of pavement layer and bearing capacity besides the seasonal and mechanical properties of pavement materials to take an appropriate and reasonable design of the road structure. In this paper, the evaluation of frost susceptibility on subgrade, ant-freezing layer, subbase was conducted by means of the mechanical characteristics and model experiment. The temperature, heaving amount, unfrozen water contents and freezing depth of soil samples, the subgrade, anti-freezing layer, subbase soils of road construction site were measured to determine the frost susceptibility.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.39-48
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• 2023

Over 100 countries have conducted research on experimental testing methods to assess the frost susceptibility of soils. This study aims to prevent structural damage caused by frost heave. Notably, the United States and Japan, which encompass cold regions such as Alaska and Hokkaido, have actively pursued frost heave research. Through laboratory investigations and field applications, standard testing methods and criteria for evaluating frost susceptibility have been established. However, these methods are complex and their engineering explanations are vague. This study closely compares and analyzes the frost-susceptibility testing methods proposed by ASTM and JGS, considering temperature conditions, specimen size, freezing direction, and drainage conditions. By conducting this comparative analysis, this study aims to shed light on the similarities and differences between the two methods. Furthermore, based on the findings, this study proposes future research guidance for refining frost-susceptibility testing methods and criteria.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6C
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• pp.241-253
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• 2010

For seismic design of a vertical shaft, three-dimensional Finite Element (FE) analyses were performed to evaluate the accurate response of a vertical shaft and to apply a Response Displacement Method (RDM). Special attention is given to the evaluation of seismic base and response displacement of surrounding soil, estimation of load and loading method. Based on the result, it was found that shear wave velocity of seismic base greater than 1500m/s was appropriate for the seismic design. It was also found that double cosine method which evaluates a response displacement of surrounding soil was most appropriate to consider the characteristic of multi-layered soil. Finally, shape effect of the structure was considered to clarify the dynamic behavior of vertical shaft and it would be more economical vertical shaft design when a vertical shaft was analyzed by using RDM.

• Korean Journal of Microbiology
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• v.45 no.2
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• pp.119-125
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• 2009

To understand the ecological function of heterotrophic bacterial community in water column of large freshwater lakes in the permafrost zone, we investigated the structure and function of bacterial community in Lake Khuvsgul, Mongolia. Species composition of overall bacterial community was analyzed by denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments, and bacteria that can be cultured at 10oC were isolated and characterized. Based on the depth profile of environmental parameters, thermocline and chemocline were recognized at the 5~10 m zone of the water column. The stratified DGGE profile indicated that the discontinuity of water properties might influence the structure of bacterial community: band profiles in the 0~5 m zone were diverse with large change by depth, but the profile was relatively stable at the $\geq$10 m zone, with predominance of the band identified as Acidovorax facilis. Bacterial cultures were screened for protease, cellulase, amylase and lipase activity, and 23 isolates were selected for high activity of the hydrolytic enzymes. The isolates were identified based on their 16S rRNA gene sequences. In the surface water (zero meter depth), Acidovorax defluvii and Sphingobacterium faecium with high cellulase activity were present. Flavobacterium succinicans, Mycoplana bullata and A. facilis were stably predominant isolates at 2 m, 5 m, and $\geq$10 m depths, respectively. F. succinicans isolates showed high protease activity while M. bullata isolates showed moderate levels of protease and celluase activity. A. facilis isolates showed either cellulase or lipase activity, exclusively to each other. According to the profile of growth rates of the isolates in the temperature range of $0\sim42^{\circ}C$, the surface-zone (0~5 m) isolates were facultative psychrophiles while isolates from $\geq$10 m depth were typical mesophiles. This stratification is believed to be due to stratified availability of organic materials to the bacterial decomposers. In the water column below the chemoline, the environment is extremely oligotrophic so that the trait of rapid growth in low temperature might not be demanded by deep-lake decomposers. The stratified distribution of community composition and decomposer activity in Lake Khuvsgul implies that ecological functions of bacterial community in lakes of cold region are sharply divided by water column stratification.

• Korean Journal of Remote Sensing
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• v.38 no.2
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• pp.139-151
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• 2022

SAGD (Steam-Assisted Gravity Drainage) method is widely used for oil recovery in oil sands regions. The SAGD operation causes surface displacement, which can affect the stability of oil recovery plants and trigger various geological disasters. Therefore, it isimportant to monitor the surface displacement due to SAGD in the oil sands region. In this study, the surface displacement due to SAGD operations of the Athabasca oil sands region in Alberta, Canada, was observed by applying Permanent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique to the Sentinel-1 time series SAR data acquired from 2016 to 2021. We also investigated the construction and expansion of SAGD facilitiesfrom Landsat-7/8 time seriesimages, from which the characteristics of the surface displacement according to the oil production activity of SAGD were analyzed. Uplift rates of 0.3-2.5 cm/yr in the direction of line of sight were observed over the SAGDs and their vicinity, whereas subsidence rates of -0.3--0.6 cm/yr were observed in areas more than several kilometers away from the SAGDs and not affected by oil recovery activities. Through the analysis of Landsat-7/8 images, we could confirm that the SAGDs operating after 2012 and showing high oil production activity caused uplift rates greater than 1.6 cm/yr due to the subsurface steam injection. Meanwhile, very small uplift rates of several mm per year occurred over SAGDs which have been operated for a longer period of time and show relatively low oil production activity. This was probably due to the compression of reservoir sandstone due to continuous oil recovery. The subsidence observed in areas except for the SAGDs and their vicinity estimated to be a gradual land subsidence caused by melting of the permafrost. Considering the subsidence, it was expected that the uplift due to SAGD operation would be greater than that observed by the PSInSAR. The results of this study confirm that the PSInSAR can be used as an effective means for evaluating productivity and stability of SAGD in the extreme cold regions.

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.5-16
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• 2012

The second scientific antarctic station of South Korea is under construction at Terra Nova Bay located in eastern Antarctica. Ground condition in the Antarctica is frozen in general, but there are seasonal frozen grounds with active layers sporadically. When the active layer is frozen, frost heaving occurs that might cause the differential movement of frozen ground and the failure of structures. Therefore, it is necessary to determine the frost heaving susceptibility of soils at Terra Nova Bay before starting antarctic station construction. This study presents experimental investigation of the frost heaving susceptibility of soil samples with variation of particle sizes and unfrozen water contents. The soil samples were taken from five different locations at Terra Nova Bay and physical properties, unfrozen water content, and frost heaving tests were performed. For the frost heaving tests, soil specimens were frozen with constant freezing temperatures at the top and with drainage at the bottom in order to stimulate the frost heaving. The frost heaving tests provide volume expansion, volumetric strain, and heaving rate which can be used to analyze the relationship between the frost heaving vs. particle size and the frost heaving vs. unfrozen water content. Experimental results show that the more the fine contents exist in soils, the more frost heaving occurs. In addition, the frost heaving depends on unfrozen water content. Experimental data can be used to evaluate the frost heaving susceptibility of soils at the future construction site in the Antarctica.

• International Commerce and Information Review
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• v.15 no.3
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• pp.313-332
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• 2013

Large tundra of the Russian Empire, has rich resources and science and technology, and a huge domestic market potential is rapidly changing. Based on the abundant energy resources such as oil, gas, and minerals, as foreign trade is active, the huge capital is moving. And commitment the active SOC by improving laws and regulations and changes in the structure of the Russian economy. One of them pushed the WTO since 1993, 19 years to see fruition join the WTO (World Trade Organization). As the official entry into force August 22, Russia, July 10, 2012, Congress passed the treaty after joining the WTO and of the 156th WTO member countries, was officially join. As the WTO, Russia has the world's 11th-largest economy in the steel tariffs from 30% to 15% are exported to Russia, South Korea Car TV parts from 10% to 0%, reduced from 20% to 5% Korean export companies to export to Russia, etc., is expected to become the new land of opportunity. Russia hopes the changes improve the investment environment, the service industry, manufacturing revitalization the macroeconomic sectors of the economy through the WTO, and forecast, but the consumption increased revenue due to tariff cuts, falling import prices and the real economy, and weak manufacturing base. On the one hand, the perspective of concern. In conclusion, Russia joining the WTO, and the feed to improve the fairness and transparency of the market opening, the Russian advance in Korean companies be facilitated and strong complementary cooperation, especially in manufacturing is expected. In this paper, after Russia joining the WTO, trade liberalization, and ready for a new era of economic cooperation between Korea and Russia, at the point of expanding openness to propose strategies to analyze the problems of Korean companies during the Russian advance.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.890-893
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• 2012

Gas hydrates are solid crystal structures formed by enclathration of gaseous guest species into 3-dimensional lattice structure of hydrogen-bonded water molecules. These compounds can be potentially used as an energy storage/transportation medium because they can hold a large amount of gas in a small volume of the solid phase. In addition, huge amount of natural gas, buried in seabeds or permafrost region in the form of the solid hydrate, is regarded as a future energy source. In this study, synthesized natural gas, whose composition is 90.0 mol% of methane, 7.0 mol% of ethane, and 3.0 mol% of propane, was used to identify formation behaviors of natural gas hydrates for the purpose of applying the gas hydrate to a storage/transportation medium of natural gas. According to the experimental results obtained by means of the solid-state NMR and high-resolution powder XRD methods, it is found that formed natural gas hydrates have crystal structure of the structure-II hydrate, and that methane occupies both small and large cages, while the others only occupy large ones. In addition, both the NMR spectroscopy and the gas chromatograph showed that there exists preferential occupation among the natural gas components during the hydrate formation. Compositional changes after the hydrate formation revealed that the preferential occupation is in order of propane, ethane, and methane (propane is the most preferential guest species when forming natural gas hydrates).