• Computers and Concrete
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• v.32 no.1
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• pp.61-74
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• 2023

This article investigates the wave propagation analysis of the imperfect functionally graded (FG) sandwich plates based on a novel simple four-variable integral quasi-3D higher-order shear deformation theory (HSDT). The thickness stretching effect is considered in the transverse displacement component. The presented formulation ensures a parabolic variation of the transverse shear stresses with zero-stresses at the top and the bottom surfaces without requiring any shear correction factors. The studied sandwich plates can be used in several sectors as areas of aircraft, construction, naval/marine, aerospace and wind energy systems, the sandwich structure is composed from three layers (two FG face sheets and isotropic core). The material properties in the FG faces sheet are computed according to a modified power law function with considering the porosity which may appear during the manufacturing process in the form of micro-voids in the layer body. The Hamilton principle is utilized to determine the four governing differential equations for wave propagation in FG plates which is reduced in terms of computation time and cost compared to the other conventional quasi-3D models. An eigenvalue equation is formulated for the analytical solution using a generalized displacements' solution form for wave propagation. The effects of porosity, temperature, moisture concentration, core thickness, and the material exponent on the plates' dispersion relations are examined by considering the thickness stretching influence.

• Korean Journal of Materials Research
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• v.34 no.5
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• pp.223-234
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• 2024

This review explores the potential of pillared bentonite materials as solid acid catalysts for synthesizing diethyl ether, a promising renewable energy source. Diethyl ether offers numerous environmental benefits over fossil fuels, such as lower emissions of nitrogen oxides (NO_x) and carbon oxides (CO_x) gases and enhanced fuel properties, like high volatility and low flash point. Generally, the synthesis of diethyl ether employs homogeneous acid catalysts, which pose environmental impacts and operational challenges. This review discusses bentonite, a naturally occurring alumina silicate, as a heterogeneous acid catalyst due to its significant cation exchange capacity, porosity, and ability to undergo modifications such as pillarization. Pillarization involves intercalating polyhydroxy cations into the bentonite structure, enhancing surface area, acidity, and thermal stability. Despite the potential advantages, challenges remain in optimizing the yield and selectivity of diethyl ether production using pillared bentonite. The review highlights the need for further research using various metal oxides in the pillarization process to enhance surface properties and acidity characteristics, thereby improving the catalytic performance of bentonite for the synthesis of diethyl ether. This development could lead to more efficient, environmentally friendly synthesis processes, aligning with sustainable energy goals.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.4
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• pp.1-14
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• 2024

Otters, designated as Class I endangered wildlife due to population declines resulting from urban development and stream burial, have seen increased appearances in freshwater environments since the nationwide ban on stream filling in 2020 and the implementation of urban stream restoration projects. There is a pressing need for scientific and strategic conservation measures for otters, an umbrella and vulnerable species in aquatic ecosystems. Therefore, this study predicts potential otter habitats using the species distribution model MaxEnt, focusing on Hwangguji Stream in Suwon, and proposes conservation strategies. Otter signs were surveyed over three years from 2019 to 2021 with citizen scientists, serving as presence data for the model. The model's outcomes were enhanced by analyzing 'river nature map' as a boundary. MaxEnt compared the performance of 60 combinations of feature classes and regularization multipliers to prevent model complexity and overfitting. Additionally, unmanned sensor cameras observed otter density for model validation, confirming correlations with the species distribution model results. The 'LQ-5.0' parameter combination showed the highest explanatory power with an AUC of 0.853. The model indicated that the 'adjacent land use' variable accounted for 31.5% of the explanation, with a preference for areas around cultivated lands. Otters were found to prefer shelter rates of 10-30% in riparian forests within 2 km of bridges. Higher otter densities observed by unmanned sensors correlated with increasing model values. Based on these results, the study suggests three conservation strategies: establishing stable buffer zones to enhance ecological connectivity, improving water quality against non-point source pollution, and raising public awareness. The study provides a scientific basis for potential otter habitat management, effective conservation through governance linking local governments, sustainable biodiversity goals, and civil organizations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.1
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• pp.80-89
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• 2001

The objective of this study was to introduce the current status and development strategy for the environmental restoration of stream side in Japan, and to consider the methodology which could be effectively applied to the environmental restoration of stream side in Korea. 1. We should establish a new paradigm of forest conservation and erosion control which can emphasize the restoration of the stream side ecosystem and reduce soil movement in the areas. Also, in the past, the objective of forest conservation and erosion control was to fix soil by constructing permanent structures. The direction of future forest conservation and erosion control needs to be new forest conservation and erosion control technology to prevent large scale soil movement but allow small scale soil movement to conserve sound ecosystem and biotic habitats. 2. In the past, the goal of forest conservation and erosion control planning was to fix the amount of soil movement by constructing permanent facilities. Forest conservation and erosion control planning in the future needs to change the techniques which could prevent soil movement from large scale of soil disasters, but allow soil movement effectively to a small and middle scale's soil movement. Also, it is considered to change erosion control dams from non passing type to passing type. 3. In the point of ecological conservation aspects, we should evaluate the effects of new forest conservation and erosion control methods which are emphasized on the restoration of the stream side ecosystem. Also, forest conservation and erosion control construction projects for restoring stream and river ecosystem should be planned for perfectly restorating their ecosystems by the way of sustainable maintenance and management. 4. The restoration direction of stream and river ecosystems needs to be restoring the diversity of small geographies such as waterway, shoal and puddles rather than flattening stream bed. And the restoration of the stream side ecosystem should provide continuity of the stream side environment which allows desirable biological habitats, and environmentally sound facilities to harmonize with the environment.

• Journal of Korea Water Resources Association
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• v.42 no.12
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• pp.1091-1102
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• 2009

This study developed an integrated approach to climate change and urbanization impact assessment by linking models of SDSM (statistical downscaling model), HSPF (hydrological simulation program?Fortran) and ICM (impervious cover model). A case study of the Anyangcheon watershed illustrated how the proposed framework can be used to analyze the impacts of climate change and urbanization in terms of flood control, water security and water quality. The evaluation criteria were the variations of flow and pollutant concentration duration curves. In this study, nine scenarios including three climate (present condition, A1B and A2) and three urbanization scenarios were analyzed using HSPF model. As a result, climate change is a large influence on the flowrate and the urbanization affects the pollutant concentration. Therefore, the impacts of both climate change and urbanization must be included into the watershed management and water resources planning for sustainable development.

• Journal of the Korean Institute of Educational Facilities
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• v.19 no.1
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• pp.45-53
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• 2012

Recently, as the environment issue has been stand out, people's interests in energy consumption of the building have been increased as well. Especially, university has been classified as the one of the main causes of excessive energy consumption. Therefore, domestic and foreign universities are trying to build a green campus in an attempt for sustainable development. Since early 2000s, foreign universities have been aware that one of the main causes of global warming is an excessive consumption of energy in universities. Accordingly, they adopted various energy management programs for the conservation. Ultimately, enforcing energy conservation and using alternative energy resulted in lower expense and it was a great help for the universities. On the other hand, excessive consumption of energy in domestic universities has been considered as serious, which led them to become the second main energy consumers in 2010. However, it seems people do not truly recognize the impotance of energy management, therefore, relatively little attention has been paid to this matter. Based on Leadership in Energy & Environmental Design(LEED) rating systems for on-campus building operation and maintenance, this research suggests the evaluation standard to effectively analyze the energy management activity with the best practices conducted in foreign universities and to solve the problem of campus facilities management in domestic universities. The result shows that domestic universities do not have a designated task force for effective energy management and the lack of energy professionals hinders for the long term development. Therefore, domestic universities should recognize the seriousness of the excessive energy consumption and develop low carbon green campus through proactive management practices since this is very essential for domestic universities to get more competitive in this global era.

• Journal of Forest and Environmental Science
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• v.29 no.1
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• pp.15-28
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• 2013

Protected area based ecotourism is now the most interesting topic to the nature lover and policy maker throughout the world because of its linkage with economic benefits, protected area management and biodiversity conservation. Based on this premise our study explores the visitors' perception on the recreational potential of Kaptai National park and its potentiality in ecotourism development in Bangladesh. The field survey was carried out both in holidays and non-holidays of the week from the late winter season in 2009 to the spring season in 2010. A total of 118 visitors were interviewed with the help of a semi-structured questionnaire. Study findings revealed that about 62% male constitute the visitors group with the maximum number of visitors in the age of between 15-25 years (35.59%). The tourists were very much attracted by boat riding (93.22%) followed by scenic beauty of Rampahar-Sitapahar (85.59%). A major portion of about 57.14% tourists wished to visit the park within a year because they got a lot of pleasure from Natural and green environment (86.44%) followed by boating on Kaptai Lake (85.59%). Most of the visitors (36%) were happy about existing facilities but defined some problems such as tour guiding facility, food and drinking water supply, etc. About 71% and 66% respondents perceived that Kaptai National Park made them to be concerned and protective of nature and supports and sustains local ecosystem respectively and 43% respondents agreed that Kaptai National Park ensures the social equity and involve local people in ecotourism which are the most important elements of sustainable ecotourism. The present study results also predict that the park might be a good recreational area for enjoying with family members and group of friends through proper management and promoting the relationships among tourism, local people and biodiversity conservation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.4
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• pp.221-230
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• 2017

Demographic change was considered to be the most major driver of land use change although there were several interacting factors involved, especially in the developing countries. This paper presents an approach to predict the future land use change using a hybrid model. A hybrid model consisting of logistic regression model, Markov chain (MC), and cellular automata (CA) was designed to improve the performance of the standard logistic regression model. Experiment was conducted in Giao Thuy district, Nam Dinh Province, Vietnam. Demography and socio-economic variables dealing with urban sprawl were used to create a probability surface of spatio-temporal states of built-up land use for the years 2009, 2019, and 2029. The predicted land use maps for the years 2019 and 2029 show substantial urban development in the area, much of which are located in areas sensitive to source protections. It also showed that aquacultural land changes substantially in areas where are in the vicinity of estuary or near the sea dike. There was considerable variation between the communes; notably, communes with higher household density and higher proportion of people in working age have larger increases in aquacultural areas. The results of the analysis can provide valuable information for local planners and policy makers, assisting their efforts in constructing alternative sustainable urban development schemes and environmental management strategies.

• Journal of the Korean Society of Earth Science Education
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• v.8 no.3
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• pp.281-296
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• 2015

The ultimate goal of environment education plays an important role in forming knowledge, skill, attitude and a point of value along with sustainable development in the regions. Recently, however, environment education is comparatively despised due to college-entrance-exam-focused education policy. Ironically, environment education is more actively implemented at informal institutes rather than formal ones. Environment education at schools is based on the school curriculum, but at informal educational institutes enjoy much more freedom in choosing learners, places and programs. Among them, the place is one of the most important factors of environment education. Therefore, in order to maximize the goal of environment education in this study, a specified program was developed and applied to a certain place to investigate its features and effects. Also the program was checked if it reflexes the environment education goal by using environment education program analysis frame. The results are as follows; according to the analysis of the program, the program was most effective for the two goals of offering hands-on experience and presenting motivations. The second most effective result of the program lied in the goal of knowledge, functions, value and attitude. And the teachers who used this program concluded that, when the program was applied to unmanned islands, offered stronger motivation due to their natural surroundings. Furthermore, direct experience is recommended because it can give us better conditions to collect data and to enhance interpretation ability.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.3
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• pp.23-29
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• 2015

The environmental friendly well being food is currently more concerning with being important for living together between human and nature worldwide by inducing the abnormal weather and global warming effect. Organic farming in Korea is slightly developed for past 100 years compared with the advanced country. However, world market of organic farming will be expanded in the future. According to holding 2015 Goesan World Organic Agriculture Industry Expo (WOAIE) from Sept. 18 to Oct. 11 organic farming in Korea will be developed. For being the safe and successful Expo, indices for 5 sectors are developed as SSaM-GG(Shared, Smart, and Mutual-Green Growth) with emphasis on reduction of accidents.