• Ocean and Polar Research
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• v.35 no.2
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• pp.157-170
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• 2013

We investigated the seasonal succession of phytoplankton assemblages in the eastern part of the South Sea of Korea in relation to surface water masses. The study areas are under the direct influence of the Tsushima Warm Current (TCW) throughout the whole year, with its strength known to be seasonally variable. The region is also influenced by coastal waters (CW) driven from the South Sea of Korea and East China Sea, particularly in summer, as indicated by low salinity in the surface water. Nutrient property of the TCW can reveals whether the origin of the TCW is the nutrient-rich Kuroshio Current or the oligotropic Taiwan Warm Current. Surface chlorophyll-a (Chl-a) concentrations displayed a large seasonal variation for all stations, with high values found in spring and autumn and low values in summer and winter. At station M (offshore) and P (intermediate location between M and R), Chl-a concentrations in October were higher than those in March, when spring bloom normally occurs. This may be related to deeper mixed layer depths in October. Diatoms dominated under conditions of high nutrient supply in which Chaetoceros spp. and Skeletonema costatum-like spp. were abundant. S. costatum-like spp. dominated at stations R (onshore station) and P in December when there was greater nutrient supply, especially of phosphate. Flagellates and dinoflagellates dominated at all three stations after diatoms blooms. Dominant species were Scrippsiella trochoid in April and Ceratium furca in October at station R, and Gyrodinium spp. and Gymnodinium spp. at station M during summer, when the effect of the oligotropic Taiwan Warm Current and the oligotropic coastal water from East China Sea were strong. Redundancy analysis showed clear seasonal successions in the phytoplankton community and environmental conditions, in which both principal components 1 and 2 accounted for 69.6% of total variance. Our results suggested that environmental conditions seemed to be determined by the origin of the TCW and the relative seasonal strength of the water masses of the TCW and CW, which may affect phytoplankton growth and compositions in the study area.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.623-646
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• 2021

As the demand for electric power increases with acceleration of electrification at home and abroad, the needs for coal-fired electrical power plant are accordingly increased. However, these coal-fired electrical power plants induce also many environmental problems such as increase of air pollutants, increase of possibility of land contamination by reclamation of coal ash, even though these power plants have a good economical efficiency. In case of a by-product of coal-fired electrical power plants, only 70% of them are recycled and the remaining 30% of by-product are fully buried in surrounding ground. Consequently, this study deals with coal ash backfilling mechanism in abandoned mine openings for the purposes of increasing the coal ash recycling rate as well as securing the mine area stability. In order to analyze the backfill and ground reinforcement by interaction between rock mass and backfills, the copying samples of discontinuous surface with different roughnesses were produced for bond strength tests and direct shear tests. And statistical analysis was also conducted to decide the characteristics of bond and shear behavior with joint roughness and their curing day. Numerical simulations were also analyzed for examining the effect of interface behavior on ground stability.

• Spatial Information Research
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• v.17 no.1
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• pp.117-129
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• 2009

South Korea has been undergoing spring drought periodically and diverse researches using vegetation index have been carried out to monitor spring droughts. The strength of the vegetation index-based drought monitoring is that the monitoring method enables efficient spatio-temporal grasp of changes in drought events. According to the development of low resolution satellite images such as MODIS, which are characterized by outstanding temporal resolution, the use of the method is expected to increase. Drought analysis using vegetation index considered only meteorological factor as a cause that affects vitality of vegetation. But many indirect and direct factors affect vegetation stress, So many uncertainties are involved in such method of analysis. To secure objectivity of drought analysis that uses vegetation index it is therefore necessary to compare the method with most representative drought analysis tools that are used for drought management. In this study, PDSI and SPI which a meteorological drought index that quantifies drought and that is used as a basic index for drought monitoring and MODIS NDVI are compared to propose correlation among them and to show usefulness of drought assessment that uses vegetation index. This study shows changing patterns of NDVI and SPI 6-month are similar and correlation between NDVI and SPI was highest in inland vegetation cover.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.13
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• pp.5411-5416
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• 2014

Background: A number of studies have reported relationships of CYP2E1 RsaI/PstI polymorphisms with susceptibility to lung cancer in Chinese population. However, the epidemiologic results have been conflictive rather than conclusive. The purpose of this study was to address the associations of CYP2E1 RsaI/PstI polymorphisms with lung cancer risk in Chinese population comprehensively. Materials and Methods: Systematic searches were conducted in the PubMed, Science Direct, Elsevier, CNKI and Chinese Biomedical Literature Databases. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to estimate the strength of association. Results: Overall, we observed a decreased lung cancer risk among subjects carrying CYP2E1 RsaI/PstI c1/c2 and c1/c2+c2/c2 genotypes (OR=0.76, 95%CI: 0.64-0.90 and OR=0.78, 95%CI: 0.66-0.93, respectively), as compared with subjects carrying the c1/c1 genotype. In subgroup analysis, we observed a decreased lung cancer risk among c1/c2 carriers in hospital-based studies (OR=0.81, 95%CI: 0.68-0.98) and among carriers with c1/c2 and c1/c2+c2/c2 genotypes in population-based studies(OR=0.57, 95%CI: 0.42-0.79 and OR=0.58, 95%CI: 0.43-0.79, respectively), as compared with subjects carrying the c1/c1 genotype. Limiting the analysis to studies with controls in Hardy-Weinberg equilibrium (HWE), we similarly observed a decreased lung cancer risk among c1/c2 and c1/c2+c2/c2 carriers (OR=0.73, 95%CI: 0.60-0.88 and OR=0.73, 95%CI: 0.60-0.88, respectively), as compared with c1/c1. Conclusions: Our results suggested that CYP2E1 RsaI/PstI c1/c2 and c1/c2+c2/c2 variants might be a protective factor for developing lung cancer in Chinese population. Further well-designed studies with larger sample size are required to verify our findings.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.97-106
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• 2020

Swelling properties and shear strength behavior of MgO-Sand mixtures with hydration procese of MgO are compared according to different MgO contents (W_MgO/W_Total=0, 30, 50, 70, 100%) in this study. The specimens are prepared by mixing with crushed MgO refractory bricks and silica sand. After hydration, the particle size and the specific gravity of MgO were decreases. Through microstructure observation and X-ray diffraction analysis, it is confirmed that MgO changes from the cubic structure of Periclase to the hexagonal cubic structure of Brucite after hydration. As the MgO content increases, both swelling rate and swelling pressure of the mixtures increase. W_MgO/W_Total=30% specimen shows relatively low swelling pressure and swelling rate because produced Mg(OH)₂ mainly fills the pores between sand particles. However, in the case of MgO more than 50%, swelling pressure and swelling rate increase significantly because Mg(OH)₂ fills the pores of sand particles at first and then either pushes out sand particles or Mg(OH)₂ particles after filling the pores. As a result of the direct shear test, before hydration, the mixtures show a dilative behavior on high MgO contents and a contractive behavior on low MgO contents. However, after hydration, the behavior of all mixtures changes to contractive behavior. The threshold fraction of fine (i.e., Mg(OH)₂) contents of the hydrated MgO-Sand mixtures reveals approximately 60% compared with normalized shear strength.

• Journal of the Korean GEO-environmental Society
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• v.13 no.2
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• pp.27-39
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• 2012

This research is to propose the reinforcing method and design code for the lateral behaviors of the abutment displacement induced from the rainfall infiltration on high landfill slope. First, to make the proper numerical analysis, in-situ soil (weathered granite soil) was taken, and the variance of strength parameters according to water content variance was examined by undrained direct shear test, furthermore, other soil parameters were calculated from the standard penetration test such as elastic modulus and Poisson's ratio etc,. Those parameters were used to calculate the lateral behavior of abutment by finite element method and the member force of pile in high landfill slope according to rainfall infiltration . From the results, the shoe displacement on abutment was calculated as 8.98cm, which is 3 times bigger than the allowable displacement, 3cm. To reinforce it, several reinforcing methods were selected and analyzed such as reinforced retaining wall, soil surcharge, pile reinforcing (5m enlargement, 3-line arrangement, 5m enlargement and 3-line arrangement). In case of 5m enlarged and 3-line arrangement piles, the lateral behavior of shoe showed lower value(2.26 cm) than allowable displacement.

• Journal of Technology Innovation
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• v.25 no.1
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• pp.1-34
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• 2017

It is almost impossible for firms to possess all of resources and capabilities needed to create technological innovations in modern competitive environment. This situation forces firms to conduct R&D collaboration. Therefore, this paper analyzes an effect of appropriability protecting knowledge exclusively on R&D collaboration and product innovation performance. In addition, we investigate how the governmental R&D support moderates and influences those relationships through empirical analysis. The results of moderated mediation show that the impact of appropriability on product innovation performance appears to be a common pattern in each conditional indirect effect of appropriability regardless of financial, direct, indirect R&D support of the government. The more governmental R&D supports increase over a certain level, the more conditional indirect effects of appropriability on product innovation performance increase through the vertical R&D collaboration. However, conditional indirect effects of appropriability through horizontal R&D collaboration are not significant in all levels of government R&D supports. If we utilize an analysis of moderated mediation by applying governmental R&D supports as a moderator, it is possible to analyze a significant strength of innovation policies and their performance. Therefore, this paper would make a contribution to an evolution of governmental R&D support and an effective formulation of innovation policy.

• Journal of Korea Port Economic Association
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• v.32 no.4
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• pp.193-209
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• 2016

The Mekong River is a river in the south-eastern part of the continent of Aisa. It flows through the countries of Thailand, Lao PDR, Cambodia, Myanmar, and Vietnam that are located in Indochina and are members of ASEAN. These countries are growing rapidly and many others have entered into these markets. As the number of manufactures has increased, logistics markets become very attractive to our logistics companies that want to expand their business. This study focuses on four countries, Lao PDR, Cambodia, Myanmar, and Vietnam, which have potential economic growth and shows the environment of logistics with current logistics infrastructure and related investment law and system. The goal of this study to provide, with strength, weakness, opportunities, and threats(SWOT) analysis, some strategies to enter 4 countries' logistics market with SWOT and the strategies are as follows; First, foreign direct investment in logistics is linked with logistics infrastructure projects. Our government should strengthen its role to find cooperation programs that make connect with logistics business. Second, a logistics company is better off in a consortium with other manufacturers or other logistics companies to ensure minimum cargo and reduce entry risks. Finally, the four countries' roles as a logistics bases need to divided according to their environments, to benefits of logistics connecting between India and China.

• Journal of the Korean earth science society
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• v.23 no.4
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• pp.349-356
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• 2002

In an effort to properly assess the validity of spaceborne radar altimeter measurements, we made a direct comparison of two different sea surface heights (SSH) acquired by both Topex/Poseidon (T/P) satellite and in-situ tide-gauges (T/G). This comparative analysis was conducted using the data sets collected from three locations along the eastern coast of Korea which include: Ulleungdo, Pohang, and Sokcho. In the course of the analysis of satellite altimeter, information of SSH was extracted from the T/P MGDR data sets through the application of both atmospheric and geophysical corrections. To compare the T/P data sets in parallel basis, the T/G data sets were averaged using the measured values within the peripheral radius of 55km. When compared among different locations, the compatibility between the two methods was much more significant in an offshore location (Ulleungdo) than the two onshore locations (Pohang, Sokcho). If the low-pass filtered results were compared among the sites, the offshore site exhibited the best correlations between the two methods (correlation coefficient of 0.91) than those of the onshore sites. These large differences in the strength of correlations among different locations are due to the deformation of M2, S2, and K1 tidal components used in the tidal model. In case of the offshore location, the compatibility of the two different methods were improved systematically by the low-pass filtering with an increase of the filtering duration such as up to 200 days.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.37-46
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• 2023

In this paper, the physical properties, stress deformation and strength characteristics, density and permeability characteristics of silty sand (SM) by fines content were analyzed through indoor tests. also based on the results of the indoor tests, a compact analysis was performed according to the content of SM, and the applicability of SM ground to the compacted target layer was evaluated by comparing it with the measurement data of the actual problem site. As a result of indoor tests and compression analysis, SM changed its mechanical properties from sandy soil to viscous soil when the fine particle content was 35% or higher, and using field measurement data, SM was found to have a higher compression tendency than direct subsidence. Therefore, the mechanical characteristics of SM above Fc 35% are considered to be similar to that of viscous soil, which is different from the compression characteristics of the tendency of immediate subsidence to conventional sandy soil, so it is necessary to present the mechanical characteristics of SM through further research. The research findings highlight the importance of considering consolidation settlement in silty sand (SM) when evaluating soft soil conditions. These findings can aid in revising criteria for assessing weak ground conditions by providing essential engineering property data based on varying fines content in silty sand.