• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.4
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• pp.13-30
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• 2020

This study aims to analyze the qualitative and quantitative effects of environmental policies in terms of green space management using logistic regression model(LRM). Landsat satellite imageries in 1985, 1992, 2000, 2008, and 2015 are classified using a hybrid-classification method. Based on these classified maps, logistic regression model having a deforestation tendency of the past is built. Binary green space change map is used for the dependent variable and four explanatory variables are used: distance from green space, distance from settlements, elevation, and slope. The green space map of 2008 and 2015 is predicted using the constructed model. The conservation effect of Ulsan's environmental policies is quantified through the numerical comparison of green area between the predicted and real data. Time-series analysis of green space showed that restoration and destruction of green space are highly related to human activities rather than natural land transition. The effect of green space management policy was spatially-explicit and brought a significant increase in green space. Furthermore, as a result of quantitative analysis, Ulsan's environmental policy had effects of conserving and restoring 111.75㎢ and 175.45㎢ respectively for the periods of eight and fifteen years. Among four variables, slope was the most determinant factor that accounts for the destruction of green space in the city. This study presents logistic regression model as a way of evaluating the effect of environmental policies that have been practiced in the city. It has its significance in that it allows us a comprehensive understanding of the effect by considering every direct and indirect effect from other domains, such as air and water, on green space. We conclude discussing practicability of implementing environmental policy in terms of green space management with the focus on a non-statutory plan.

• The KIPS Transactions:PartD
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• v.15D no.5
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• pp.659-668
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• 2008

Recently, the component model based on the Exogenous Connector has been proposed in which controls are separated from computation by managing the beginning and result of method calls in the connector. Although it could be loosely coupled between components, it has a problem that is a potential preponderance of element objects of the system by increasing the number of connectors and connection levels. In this paper we propose the Tree Component Model with the Hybrid Message Passing that combines direct and indirect message passing. In our model, components are wrapped by interfaces and controls are separated from computation by only using their interface references. There is a unique feature that the composition structure of components becomes the tree always. As a result of demonstration and comparison, it is found that the Tree Component Model is applicable practically and decreases objects to mediate message passing and build the system.

• Korean Journal of Food Science and Technology
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• v.32 no.5
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• pp.997-1001
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• 2000

The organic acids in 3 kinds of medicinal herbal extracts were screened and compared each other according to their organic acid contents by an efficient gas chromatographic method. It involves solid-phase extraction of organic acids using Chromosorb P with subsequent conversion to stable tert-butyldimethysilyl derivatives for the direct analysis by capillary column gas chromatography and gas chromatography-mass spectrometry. Total of 24 organic acids were reproducibly identified from 3 kinds of herbal extracts. When the GC profiles were simplified to their retention index spectra, characteristic patterns were obtained for each herb sample. As expected, three kinds of herbal extracts showed three distinct patterns.

• Interaction and multiscale mechanics
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• v.3 no.2
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• pp.192-211
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• 2010

In most framed structures the nonlinearities and the damages are localized, extending over a limited length of the structural member. In order to capture the details of the local damage, the segments of a member that have entered the nonlinear range may need to be analyzed using the three-dimensional element (3D) model whereas the rest of the member can be analyzed using the simpler one-dimensional (1D) element model with fewer degrees of freedom. An Element-Coupling model was proposed to couple the small scale solid 3D elements with the large scale 1D beam elements. The mixed dimensional coupling is performed imposing the kinematic coupling hypothesis of the 1D model on the interfaces of the 3D model. The analysis results are compared with test results of a reinforced concrete pipe column and a structure consisting of reinforced concrete columns and a steel space truss subjected to static and dynamic loading. This structure is a reduced scale model of a direct air-cooled condenser support platform built in a thermal power plant. The reduction scale for the column as well as for the structure was 1:8. The same structures are also analyzed using 3D solid elements for the entire structure to demonstrate the validity of the Element-Coupling model. A comparison of the accuracy and the computational effort indicates that by the proposed Element-Coupling method the accuracy is almost the same but the computational effort is significantly reduced.

• Journal of Powder Materials
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• v.28 no.3
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• pp.221-226
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• 2021

We fabricate the non-equiatomic high-entropy alloy (NE-HEA) Fe_49.5Mn₃₀Co₁₀Cr₁₀C_0.5 (at.%) using spark plasma sintering under various sintering conditions. Each elemental pure powder is milled by high-energy ball milling to prepare NE-HEA powder. The microstructure and mechanical properties of the sintered samples are investigated using various methods. We use the X-ray diffraction (XRD) method to investigate the microstructural characteristics. Quantitative phase analysis is performed by direct comparison of the XRD results. A tensile test is used to compare the mechanical properties of small samples. Next, electron backscatter diffraction analysis is performed to analyze the phase fraction, and the results are compared to those of XRD analysis. By combining different sintering durations and temperature conditions, we attempt to identify suitable spark plasma sintering conditions that yield mechanical properties comparable with previously reported values. The samples sintered at 900 and 1000℃ with no holding time have a tensile strength of over 1000 MPa.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.189-195
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• 2024

Road transport occupies the largest share in domestic and international transport. It is of key importance for the development of the economy, forasmuch as it provides the livelihood of the population, the development of the national economy, the possibility of establishing foreign economic relations. The purpose of the research is as follows: analysis of the current state of functioning of the road transport sector in Eastern Europe and identification of key problems and trends in its development. Research methods: Methods of grouping, comparison and generalization, correlation analisys have been used to identify the dynamics of the main indicators of road transport in Eastern Europe. The method of correlation-regression analysis has been applied to determine the impact of increasing the length of roads on the turnover of the road freight transport and the number of employed population in this area. Results. It has been found that the increase in the employed population by 96% and increase in revenues from transportation and storage of goods, postal and courier services (turnover of the road freight transport - in the original language) in the field of road transport by 82% is explained by the change in transport infrastructure capacity by increasing length of highways. According to the correlation analysis, it has been revealed that there is a high direct dependence between the length of roads and increased revenues from transportation and storage of goods in the field of road transport, as well as between the length of roads and increasing employment in this area.

• Clinical Endoscopy
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• v.56 no.1
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• pp.65-74
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• 2023

Background/Aims: Gastric varices (GV) are present in 25% of cirrhotic patients with high rates of rebleeding and mortality. Data on endoscopic ultrasound (EUS)-guided treatment in severe liver disease (model for end stage liver disease sodium [MELD-Na] >18 and Child-Turcotte-Pugh [CTP] C with GV) are scarce. Thus, we performed a retrospective comparison of endoscopic glue injection with EUS-guided therapy in cirrhotic patients with large GV. Methods: A retrospective study was performed in the tertiary hospitals of India. A total of 80 patients were recruited. The inclusion criteria were gastroesophageal varices type 2, isolated gastric varices type 1, bleeding within 6 weeks, size of GV >10 mm, and a MELD-Na >18. Treatment outcomes and complications of endoscopic glue injection and EUS-guided GV therapy were compared. Results: In this study, the patients' age, sex, liver disease severity (CTP, MELD-Na) and clinical parameters were comparable. The median number of procedures, injected glue volume, complications, and GV obturation were better in the EUS group, respectively. On subgroup analysis of the EUS method (e.g., direct gastric fundus vs. paragastric collateral [PGC] coil placement), PGC coil placement showed decreased coil requirement, less injected glue volume, decreased luminal coil extrusion, and increased successful GV obturation. Conclusions: EUS-guided treatment is more efficient and safer, and requires a smaller number of treatment sessions, as compared to endoscopic treatment in severe liver disease patients with large GV. Furthermore, PGC coil placement increases the complete obliteration of GV.

• Journal of ILASS-Korea
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• v.29 no.2
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• pp.83-90
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• 2024

Understanding the fundamental characteristics of supersonic hydrogen jets is important for the optimization of combustion in hydrogen engines. Previous studies have used helium as a surrogate gas to characterize the hydrogen jet characteristics due to potential explosion risks of hydrogen. It was based on the similarity of hydrogen and helium jet structures in supersonic conditions that has been confirmed using hole-type injectors and large-cone-angle pintle-type injectors. However, the validity of using helium as a surrogate gas has not been examined for recent small-cone-angle pintle-type injectors applied to direct-injection hydrogen engines, which form a supersonic hollow cone near the nozzle and experience the jet collapse downstream. Differences in the physical properties of hydrogen and helium could alter the jet development characteristics that need to be investigated and understood. This study compares supersonic jet structures of hydrogen and helium injected by a small-cone-angle (50°) pintle-type hydrogen injector and discusses their differences and related mechanisms. Jet penetration length and dispersion angle are measured using the Schlieren imaging method under engine-like injection conditions. As a result, the penetration length of hydrogen and helium jets showed a slight difference of less than 5%, and the dispersion angle showed a maximum of 10% difference according to the injection condition.

• Journal of Korea Water Resources Association
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• v.40 no.8
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• pp.655-663
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• 2007

This study suggests a new time distribution method of rainfall for small urban watersheds. IETD (Interevent Time definition) determination method considering basin characteristics and dimensionless accumulation rainfall curves involving rainfall events with shorter duration than 3-hours are suggested. A new definition of IETD is the time period from the end of a rainfall event to the end of a direct runoff. Using the method, we drive an area-IETD regression curve for the Joong-Rang basin. The rainfall event with 10 year-return periods, 2-hour duration is distributed and applied four urban watersheds. In the four watersheds, we calculate hydrographs for four watersheds using SWMM and compare them with ones of the Huff's distribution model. From the comparison, we find that peak flows resulted from the developed methodology are $11\sim15%$ larger than ones from the Huff's model. As conclusion, the Huff method should be adopted for the urban watersheds with careful verification.

• 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.