• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.315-328
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• 2009

Long-term trends and distribution patterns of water quality were investigated in the Garolim coastal areas of Yellow Sea, Korea from 1998 to 2007. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids(SS), chemical oxygen demand(COD), dissolved oxygen(DO) and nutrients. Spatial distribution patterns were not clear among stations but the seasonal variations were distinct except pH and ammonia. The trend analysis by principal component analysis(PCA) during twenty years revealed the significant variations in water quality in the study area. Annual water qualities were clearly classified into 4 clusters by PCA; year cluster 1997, 1998 and 2000-2002, 1999 and 2003-2006/2008. By this multi-variate analysis the annual trends were summarized as follows; In recent years, salinity increased, whereas dissolved inorganic nitrogen, nitrate nitrogen and COD decreased and water quality generally continued to be in good condition in Gsrolim coastal areas without inflow of freshwater from land. Garolim coastal areas are required to be conserved continuously as important coastal areas for fisheries.

• Journal of the Korean Vacuum Society
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• v.4 no.S2
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• pp.95-99
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• 1995

keV ion beam irradiatin for surface modification and thin film growth have been discussed. keV ion beam irradiation in reactive gas environment has been developed for improving wettability of polymer, and for enhancing adhesion to metal film, and adventages of the method have been reviewed. An epitaxial Cu film on Si(100) substrate has been grown by ionized cluster beam and changes of crystallinity and surface roughness have been discussed. Stoichiometric $SnO_2$ films on Si(100) and glass have been grown by a hybrid ion beam Deposition(2 metal ion sources+1 gas ion source), and nonstoichiometric $SnO_2$ films are controlled by various deposition conditions in the HIB. Surface modification for polymer by kev ion irradiation have been developed. Wetting angle of water to PC has been changed from 68 degree to 49 degree with $Ar^+$ irradiation and to 8 degree with $Ar^+$ irradiation and the oxygen environment. Change of surface phenomena in a keV ion beam and characteristics of the grown films are suggested.

• KIEAE Journal
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• v.8 no.4
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• pp.11-18
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• 2008

This research case-study places are chosen Seoul Metropolitan City and Yong-In City where the distinction characteristics of outdoor spaces are introduced in Apartment Complex. In this study, the standard of waterscape facilities will be set through preliminary researches and detail design factors are prepared for each characteristics. Analyze and research the characteristics of design factors through the field research of places. The Group data from Cluster Analysis, which is about waterscape facilities, is analyzed and classified by types of waterscape facilities in common residence. and then each type of characteristics and representatives of waterscape facilities founded. Waterscape facilities are charactered in 4 main types. I Type is appeared to the natural artificially mountain stream, slope and a rest space type, and feelings type. This type has twenty sites. II Type is appeared to the fewest sites(11 sites). This type is appeared to the Eco-pond, Border planting next to the waterscape facilities. III Type is appeared to the largest sites(28 sites), that is, play style water facilities of no-plantation patterns. IV Type is appeared to the retaining wall type, the rest space of bench type. Research result led, detailed plan element 64 are selected with design elements Seoul Metropolitan City and the Yong-In City at the time of the fact that well is only reflected commonly from external spaces, the type by quality which leads a statistical analysis the type quality was well reflected relatively was judged.

• Architectural research
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• v.21 no.4
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• pp.91-98
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• 2019

In modern times, numerous cities are competing to create the unique skyline adjacent to the water. Tall buildings located across the river have a great contribution to the skyline of a riverfront city and can be a precious asset for the city. Moreover, in several cities, tall buildings and their impact on the urban skyline are a matter that should be considered and regulated in urban design. Therefore, as a prominent element in a larger visual setting of the city, tall buildings should improve the visual quality of the skyline rather than diminish that quality. This research attempts to provide an objective method to analyze the visual quality of the skyline made by a group of tall buildings through their feature of heights and spatial arrangement from riverfront views. The analysis is determined by the design variables of building heights variation, heights transition, density, and spacing of a group of tall buildings. A comparative case study of tall buildings in Yeouido and Lujiazui was conducted to prove the effectiveness of the analysis. The proposed method can be used in a simple way in the quantitative approach to quantify the visual quality of the skyline. In conclusion, Yeuido's skyline is not quite interesting from the riverfront view in terms of height variation and continuity of the skyline view because they are dispersed. Conversely, Lujiazui's skyline from the riverfront vantage points has a good quality in all aspects of the feature of height and spatial arrangements of tall buildings cluster. These factors can be used for the urban designer on how proposed tall buildings within the cluster should appropriately respond to adding image on the skyline.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.297-299
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• 2021

Predicting future productivity of tight oil is an important task for analyzing residual oil recovery and reservoir behavior. In general, productivity prediction is made using the decline curve analysis(DCA). In this study, we intend to propose an effective model for predicting future production using deep learning-based recurrent neural networks(RNN), LSTM, and GRU algorithms. As input variables, the main parameters are oil, gas, water, which are calculated during the production of tight oil, and the type curve calculated through various cluster analyzes. the output variable is the monthly oil production. Existing empirical models, the DCA and RNN models, were compared, and an optimal model was derived through hyperparameter tuning to improve the predictive performance of the model.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.341-344
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• 2007

A major obstacle to classify and validate Land Cover maps is the high cost of generating reference data or multiple thematic maps for subsequent comparative analysis. In case of inaccessible area such as North Korea, the high resolution satellite imagery may be used as in situ data so as to overcome the lack of reliable reference data. The objective of this paper is to investigate the possibility of utilizing QuickBird (0.6m) of North Korea obtained from Google Earth data provided thru internet. Monthly NDVI images of nine months from the summer of 2004 were classified into L=54 cluster using ISODATA algorithm, and these L clusters were assigned to 7 classes; coniferous forest, deciduous forest, mixed forest, paddy field, dry field, water and built-up area. The overall accuracy and Kappa index were 85.98% and 0.82, respectively, which represents about 10% point increase of classification accuracy than our previous study based on GCP point data around North Korea. Thus we can conclude that Google Earth may be used to substitute the traditional in situ data collection on the site where the accessibility is severely limited.

• Korean Journal of Remote Sensing
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• v.23 no.5
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• pp.483-491
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• 2007

One of the major obstacles to classify and validate Land Cover maps is the high cost of acquiring reference data. In case of inaccessible areas such as North Korea, the high resolution satellite imagery may be used for reference data. The objective of this paper is to investigate the possibility of utilizing QuickBird high resolution imagery of North Korea that can be obtained from Google Earth data via internet for reference data of land cover classification. Monthly MODIS NDVI data of nine months from the summer of 2004 were classified into L=54 cluster using ISODATA algorithm, and these L clusters were assigned to 7 classes - coniferous forest, deciduous forest, mixed forest, paddy field, dry field, water, and built-up areas - by careful use of reference data obtained through visual interpretation of the high resolution imagery. The overall accuracy and Kappa index were 85.98% and 0.82, respectively, which represents about 10% point increase of classification accuracy than our previous study based on GCP point data around North Korea. Thus we can conclude that Google Earth may be used to substitute the traditional reference data collection on the site where the accessibility is severely limited.

• Economic and Environmental Geology
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• v.39 no.6 s.181
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• pp.753-770
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• 2006

In urban areas, groundwater pollution is heavily affected by urbanization with land use types. This study aims to characterize groundwater quality and contamination in Sasang industrial area of Busan Metropolitan City where metalworking, machinery and footwear factories are located. Busan Metropolitan City is the highest in the utilization of groundwater resources among the metropolitan cities in Korea. $K^+,\;Na^+,\;Ca^{2+},\;Mg^{2+},\;Cl^-,\;SO_4^{2-}\;and\;HCO_3^-$ concentrations, and electrical conductivity (EC), total dissolved solids (TDS) and salinity are high in the areas near the Nakdong River. The results are attributed to the influence of salt water which intruded into the coastal sediments during sedimentation. In addition, the dominant chemical type of Ca-Cl indicates the influence of salt water in the geological formations as well as anthropogenic pollution. $SiO_2$ ion is interpreted to originate from both water-silicate mineral reactions and the decomposition of cement concretes. Trichloroethylene (TCE) was detected at 12 sites of total 18 sites. However, tetrachloroethylene (PCE) was detected at f sites and 1.1.1-trichloroethane (TCA) at 3 sites. According to the factor analysis, factor 1 was explained by 49.8%, factor 2 19.8%, and factor 3 11.0% with total 80.6% explanation. pH, TDS, salinity, $Ca^{2+},\;K^+,\;Mg^{2+},\;Na^+,\;Al^{3+},\;As^{3+},\;Cl^-\;and\;Fe^{2+}$ were positively highly loaded to factor 1. The chemical components loaded to factor 1 represent the chemical characteristics of both industrial pollution and influence by salt water. Based on the cluster analysis and distribution pattern of chemical components, the concentration of $Na^+,\;Ca^{2+},\;Cl^-,\;SO_4^{2-}\;K^+,\;and\;Mg^{2+}$ is high in the riverside area of the Nakdong River composed of coastal sediments that is influenced by salt water. The downstream area of the Hakjang Stream is judged to be affected by both salt water and artificial pollution. The other part of the study area is interpreted by anthropogenic pollution.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.4
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• pp.447-455
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• 2022

Fully dehydrated Tl₁₂-LTA (|Tl₁₂|[Si₁₂Al₁₂O₄₈]-LTA,Tl₁₂-A) was treated with 6.0×10³ Pa of ZrI₄ (g) at 623 K for 72 hr under anhydrous conditions. The crystal structure of product, |Zr_0.25I_1.5Tl₁₂|[Si₁₂Al₁₂O₄₈]-LTA, was determined by single-crystal crystallography using synchrotron X-radiation in the cubic space group Pm3m (a = 12.337(2) Å). It was refined using all data to the final error index (for the 712 unique reflections for which F_o> 4σ(F_o) R₁/wR₂= 0.055/0.189. In this structure, octahedral ZrI₆^2- ions center about 25% of the large cavities (Zr-I = 2.91(4) Å). Each coordinates to eight Tl⁺ ions and they are further bridged by Tl⁺ ions in the planes of 8-rings to form a cubic three-dimensional ZrI₆Tl₁₁⁹⁺ cationic cluster. About 1.5 Tl⁺ ions per unit cell moved to deeper side of sodalite cavity after reaction with ZrI₄(g). The remaining Tl⁺ ions occupy well-established cation positions near 6- and 8-rings.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.151-157
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• 2011

Crosslinked SPEEK/PVDF membrane were prepared by EB radiation method with various contents of PVDF. The prepared membranes were subjected to a comparative study of proton exchange membranes for fuel cell appreciations. The crosslinked SPEEK/PVDF membranes were characterized by using DMA, DSC and SAXS. The DMA data indicate that the ionic modulus values and cluster $T_g$ decrease with increasing PVDF content. Thus, it was suggested that the number of clustering in the crosslinked membranes can be reduced with increasing PVDF content. The DSC results were shown that the degree of crystalline of the membrane increased with increasing PVDF content. The morphology of the crosslinkied membranes was shown that with increasing PVDF content, the number of crystalline domain of the SPEEK/PVDF membranes increased but ionic aggregation of the membranes decreased. The water uptake behavior, ionic exchange capacity (IEC) and proton conductivity were decreased with increasing PVDF content. The overall findings suggest that the crosslinked membranes offer the possibility for improving the performance of PEMFC, provided that the membranes have thermal and hydration stability.