• Journal of the Korean Society for information Management
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• v.35 no.4
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• pp.125-140
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• 2018

Circulation data is a key data set of academic libraries in terms of collection development and service improvement This study aims to identify the characteristics of circulation measures and their feasibility. This study collected the circulation data of 10 colleges in a university and analyzed 4 measures based on the circulation data: circulation frequency, circulation entropy, circulation h-index, and circulation divergence. These measures are to present the circulation topics of each college. This study identified that circulation entropy tends to present general topics which are popular for many colleges, but circulation divergence tends to present specific topics which are preferred by a specific college.

• Atmosphere
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• v.24 no.2
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• pp.141-150
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• 2014

This study investigates the characteristics of the Gross Moist Stability (GMS) over the tropics. The GMS summarizes the relationship between large-scale entropy forcing due to radiation and surface fluxes and the response of smaller-scale convection. The GMS is able to explain both to where moist entropy is advected by the atmospheric circulation and how deep the moisture flux convergence is in the tropical region. In the deep convective region, positive GMS appears over the warm pool region due to the strong column-integrated moisture convergence and the ensuing export of moist entropy to the environment. The vertical advection of moist entropy dominates over the horizontal advection in this region. Meanwhile, over the eastern tropical ITCZ region, which is characterized by shallow convective area, import of moist entropy by horizontal winds is dominant compared to the vertical moist entropy advection. Future changes in the GMS are also examined using the 22 CMIP5 model simulations. A decrease in the GMS appears widely across the tropics, but its increase occurs over the western-central equatorial Pacific. It is evident that the increased GMS region corresponds to an increased region of precipitation, implying that strengthened convection in the future due to increased entropy forcing exports the enhanced moist energy to stabilize the environment.

• Journal of Climate Change Research
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• v.1 no.1
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• pp.59-73
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• 2010

One of the most important issues for projecting future water resources and establishing climate change adaptation strategies is 'uncertainty'. In Korea, climate change research results were very heterogeneous even in a same basin, but there have been few climate change studies dealt with the uncertainty reduction. This is because emission scenarios, GCMs, downscaling, and rainfall-runoff models that were used in the previous studies were almost all different. In this research, fifty one GCM scenarios based A and B emission scenarios were downloaded and then compared with the observed values for a period from January 2001 to December 2008. The downloaded GCM scenarios in general simulated well the observed but did not simulated well the observed precipitation especially for the flood season in Korea. The accuracy of each GCM scenario was measured with the model efficiency, PDF-based, and Relative Entropy methodology. Among the selected GCM scenarios with three methodologies, the four common GCM scenarios(CGCM2.3.2(MRI-M, B1), MIROC3.2medress(NIES, B1), CGCM2.3.2(MRI-M, A2), CGCM2.3.2(MRI-M, A1B) were finally selected. Results of the four selected GCMs were heterogeneity and projected increases of precipitation for the Korean Peninsula by from 27.36% to 12.49%, respectively. It seems very risky to rely a water planning or a management policy on use of a single climate change scenario and from this research results. Therefore, the four selected GCM scenarios proposed quantitatively were considered firstly for the water supply in the dry season and the drought management strategy in the Korean Peninsula for the future.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.2
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• pp.12-27
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• 2023

In this study, among the construction-type parks in Gangdong-gu, targeting parks with high environmental and ecological value located on the urban green axis, a plan was prepared for the ecological renewal of urban parks, and a design that applied to them was proposed. The renewal target site was selected by analyzing the general condition of Gangdong-gu and urban parks, the land use and green area ratio, park green area, and the green axis of Gangdong-gu. Gangdong-gu has 54 parks, including 2 neighborhood parks and 52 children's parks. In the first stage of the current status review, 17 parks were extracted through locational value analysis, such as location and adjacency to the natural axis and green axis. In the second stage, eight parks were selected among the first-stage extraction parks based on the ratio of green spaces and open spaces within each park service area. In the third stage, two of the second stage extraction parks were selected based on whether the legal standard of the park area was met, and in the fourth stage, one of the third stage extraction parks was selected through an aging survey of the park. As for the urban ecological status of the renewal target site, the status of land use in the aspect of entropy reduction, the status of soil cover in the aspect of water circulation, and the status of planting structure in the aspect of biodiversity were investigated. As for the status of the three renewal sites, the green area was insufficient at 18.3-45.3%, and the facility area was 54.7%-81.7%, which was judged to have low urban temperature reduction effects. The impervious pavement area accounted for 34.5% to 48.9% of the park area, accounting for most of the facility area, and it was judged that the water circulation function was insufficient. The planting structure consisted of a single layer and a double layer structure, and although the tree layer was good, the lower vegetation was poor, and there was no planting site of edible plants or large hardwood trees, so the biodiversity was low. After the ecological renewal design of Seonrin Children's Park, Dangmal Children's Park, and Saemmul Children's Park, which were selected as the renewal targets in this study, the ecological area ratio of each park increased by 1.4 to 3 times than before the renewal. If the urban parks located on the urban green axis are examined from the perspective of the urban ecosystem and renewed ecologically, it is judged that the expected effect will be high in reducing entropy, improving water circulation, and laying the foundation for biodiversity in terms of the urban ecosystem.

• International Journal of Vascular Biomedical Engineering
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• v.3 no.1
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• pp.14-22
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• 2005

In the present study, our aim is to investigate whether responses to the head-up tilt (HUT) on nonlinear properties of heart rate variability (HRV) in young and elderly subjects are different or not. Thirteen young-healthy subjects ($24.5{\pm}3.7$ years) and 18 old-aged healthy subjects ($74.5{\pm}7.4$ years) participated in this study. An electrocardiogram (ECG) in the supine posture, at $0^{\circ}$, and in the standing posture, at $70^{\circ}$ of head-up tilt, was recorded. Detrended fluctuation analysis (DFA) and approximate entropy (ApEn), measures of short-/long-term correlation properties and overall complexity of heart rate (HR) respectively, along with spectral components of HR variability (HRV) were analyzed for both the supine and HUT postures. We observed that the short-term fractal exponent ${\alpha}_1$ increased during HUT posture (F(1, 29) = 39.79, P = 0.000), especially, the young subjects showed a significantly higher values compared to the elderly subjects. ApEn significantly decreased (F(1, 29) = 8.61, P = 0.006) during HUT posture. HUT posture decreased the complexity in HR dynamics and increased short-term fractal exponent values in young subjects but not in elderly subjects. These results imply that there are differences of response to HUT on nonlinear properties between young and elderly subjects.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.12
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• pp.775-780
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• 2008

A dynamic model to simulate LNG reliquefaction process has been developed. The model was applied to two candidate cycles for LNG reliquefaction process, which are Reverse Brayton and Claude cycles. The simulation was intended to simulate the pilot plant under construction for operation of the two cycles and evaluate their feasibility. According to the simulation results, both satisfy control requirements for safe operation of brazed aluminum plate-fin type heat exchangers. In view of energy consumption, the Reverse Brayton cycle is more efficient than the Claude cycle. The latter has an expansion valve in addition to the common facilities sharing with the Reverse Brayton cycle. The expansion valve is a main cause to the efficiency loss. It generates a significant amount of entropy associated with its throttling and increases circulation flow rates of the refrigerant and power consumption caused by its leaking resulting in lowered pressure ratio. It is concluded that the Reverse Brayton cycle is more efficient and simpler in control and construction than the Claude cycle.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.536-545
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• 2019

An experiment was conducted to evaluate the adsorptive removal of Pb(II) from an aqueous solution using a mixture of spent coffee grounds and chitosan on beads (CC-beads). Various parameters affecting the adsorption process of Pb(II) using CC-beads were investigated. Based on the experimental data, the adsorption kinetics and adsorption isotherms were analyzed for their adsorption rate, maximum adsorption capacity, adsorption energy and adsorption strength. Moreover, the entropy, enthalpy and free energy were also calculated by thermodynamic analysis. According to the FT-IR analysis, a CC-bead has a very suitable structure for easy heavy metal adsorption. The process of adsorbing Pb(II) using CC-beads was suitable for pseudo-second order kinetic and Langmuir model, with a maximum adsorption capacity of 163.51 (mg/g). The adsorption of Pb(II) using CC-beads was closer to chemical adsorption than physical adsorption. In addition, the adsorption of Pb(II) on CC-beads was exothermic and spontaneous in nature. CC-beads are economical because they are inexpensive and also the waste can be recycled, which is very significant in terms of the continuous circulation of resources. Thus, CC-beads can compete with other adsorbents.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.4
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• pp.135-140
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• 2009

A dynamic model to simulate LNG reliquefaction process has been developed. The model was applied to two candidate cycles for LNG reliquefaction process, which are Reverse Brayton and Claude cycles. The simulation was intended to simulate the pilot plant under construction for operation of the two cycles and evaluate their feasibility. According to the simulation results, both satisfy control requirements for safe operation of brazed aluminum plate-fin type heat exchangers. In view of energy consumption, the Reverse Brayton cycle is more efficient than the Claude cycle. The latter has an expansion valve in addition to the common facilities sharing with the Reverse Brayton cycle. The expansion valve is a main cause to the efficiency loss. It generates a significant amount of entropy associated with its throttling and increases circulation flow rates of the refrigerant and power consumption caused by its leaking resulting in lowered pressure ratio. It is concluded that the Reverse Brayton cycle is more efficient and simpler in control and construction than the Claude cycle.

• Journal of the Korean Institute of Landscape Architecture
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• v.32 no.3
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• pp.1-17
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• 2004

The focus of this study is the promotion of green area volumes and their naturalness, water circulation system, decline of entropy, creation of biological habitats and linkage of separated urban green space. Re-presentative urban biotope survey sites were categorized as urban biotope, semi-natural biotope, and natural forest. In the urban biotope, a residential biotope was constructed near the Han river and in mountain areas. The green-area ratio at the housing complex was about 25%. GVZ(Grunvolumenzahl) was 0.35m$^3$/m$^2$ at the 5∼10-story housing complex, and 1.53m$^3$/m$^2$ over the 11-story. As for the green-area structure of the housing complex, canopy layer, understory layer, and shrub layer were not differentiated and the green-area volume was not high enough. The green-area ratio of school areas as a public area biotope was 5∼20%. GVZ was 1.12m$^3$/m$^2$ at Myungduk High School, and 1.78m$^3$/m$^2$ at Jeonggok Elementary School. In order to convert the urban biotope into an ecological area, green areas around the buildings should be connected to urban buffer green areas, and multi-layer structures should be established with natural plant species. In the semi-natural biotope, neighbor parks were created park in the vicinity of the natural forests. GVZ was 0.28m$^3$/m$^2$, and plantation was established with single layer structure and was definitely insufficient for the area. The urban buffer green areas have been established in strip corridors with the width of 20∼123m. In those areas, GVZ was 0.16∼0.27m$^3$/m$^2$ and had a deficient canopy layer, understory layer, and shrub layer. Soil conditions were not favorable for tree growth. In the natural biotope, GVZ of the plantation was 1.03∼1.5m$^3$/m$^2$ but the high crown closure of this area reduces the chance of species change and succession. GVZ of natural forest was 2.53∼2.57m$^3$/m$^2$. It is desirable to plant diverse plants and the natural forest should be succeeded by broad-leaf deciduous tree species. To improve the value of biotope at Kangseo-Gu, building height needs to be limited to reduce the environmental deterioration in the city. In order to maintain the water circulation system, water-permeable material is recommened when the urban surface areas are paved. The establishment of a water circulation system will improve ground water levels, soil moisture, water quality, and habitats. In order to improve biological diversity, it is desirable to have multi-layer structures in urban green areas with native species.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.47-62
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• 2020

Rice paddy accounts for approximately 52.5% of all farmlands in South Korea, and it is closely related to the water environment. Climate change is expected to affect not only agricultural productivity also the water and the nutrient circulation. Therefore this study was aimed to evaluate changes of nitrogen load from rice paddy considering climate change scenario uncertainty. APEX-Paddy model which reflect rice paddy environment by modifying APEX (Agricultural Policy and Environmental eXtender) model was used. Using the AIMS (APCC Integrated Modeling Solution) offered by the APEC Climate Center, bias correction was conducted for 9 GCMs using non-parametric quantile mapping. Bias corrected climate change scenarios were applied to the APEX-Paddy model. The changes and uncertainty in runoff and nitrogen load were evaluated using multi-model ensemble. Paddy runoff showed a change of 23.1% for RCP4.5 scenario and 45.5% for RCP8.5 scenario compared the 2085s (2071 to 2100) against the base period (1976 to 2005). The nitrogen load was found to be increased as 43.9% for RCP4.5 scenario and 76.0% for RCP8.5 scenario. The uncertainty analysis showed that the annual standard deviation of nitrogen loads increased in the future, and the maximum entropy indicated an increasing tendency. And Duncan's analysis showed significant differences among GCMs as the future progressed. The result of this study seems to be used as a basis for mid- and long-term policies for water resources and water system environment considering climate change.