• Clean Technology
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• v.23 no.4
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• pp.345-356
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• 2017

The composting is a biological process that converts organic matter into useful resources such as fertilizers. It is a continuous transition of microbial communities to adapt changes in organic matter and environmental conditions (carbonation rate, temperature, humidity, oxygen supply, pH, etc.). Most of the composting plants are located in the proximity of the residential areas. It is a general scenario where government authorities receive complaints from the local residents due to release of odor from the composting, and has become a social problem in Korea. Identification of dominant microorganisms, understanding change in microbial communities and augmentation of specific microorganism for composting is vital to enhance the efficiency of composting, quality of the compost produced, and reduction of odor. In this paper, we suggest the optimum operation conditions and methods for compost depot to reduce odor generation. The selection of the appropriate microorganisms and their rapid increase in population are effective to promote composting. The optimal growth conditions of bacteria such as aeration (oxygen), temperature, and humidity were standardized to maximize composting through microbial degradation. The use of porous minerals and moisture control has significantly improved odor removal. Recent technologies to reduce odor from the composting environment and improved composting processes are also presented.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.307-314
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• 2016

Shear characteristics of soils can be investigated using various types of shear stress measuring apparatus. Ring shear tests are often applied for examining the residual shear strength under the unlimited deformation. This paper presents drainage-consolidation-shear velocity dependent undrained shear strengths measured in terms of water leakage. A series of ring shear tests were performed under the constant normal stress (50 kPa) and controled shear velocity ranging from 0.01~1 mm/sec under the undrained condition. As a result, undrained shear strengths are dependent on shear velocity. It exhibits that straining hardening behavior is observed for the shear velocity lower than 0.1 mm/sec; however, the strain softening behavior is observed for the shear velocity higher than 0.1 mm/sec. Water leakage can cause the increase in shear stress irrespective of shear velocity. Shear stress increases with increasing amount of water leakage. It is due to the fact that the small grains and water flow out through the rubble edge in the ring shear box. Repetitive saturation and consolidation processes may minimize the error.

• Journal of Environmental Health Sciences
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• v.22 no.3
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• pp.37-48
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• 1996

The purpose of this study is to provide the valuable basic information that helps set the advanced direction of study in environmental pollution in the future. It classifies and analyzes 6, 531 papers according to their years, fields, and contents from 1962 to 1993 in Korea through Chunrian, a PC communication network, National Environment Research Institute(1989) in Seoul. Classifying papers by their fields, this study shows 19.6%(1, 281 papers) of total papers on water pollution, on which most emphasis was placed in the studies, 17.2%(1, 121 papers) on general remarks, 14.6%(952 papers) on environmental ecology, and 13.6%(891 papers) on air pollution. Classifying papers by their contents, this study tells us that the survey of state and evaluation of pollution degree took 28%(1, 829 papers) of total papers, and it seemed the most active study was carried out on this content. It then shows us that the treatment technology and mechanism shared 17.5%(1, 144 papers), and facilities and design took 1.9%(127 papers) which needed more studies in the future. As for the trends of study, the papers published until 1979 show that the water pollution accounted for 28.9% of total studies, on which the greatest emphasis was placed, while the papers in 1990s tell us that general remarks 34.7%, air pollution 14.9%, and water pollution 14.1%. It also shows that treatment technology and mechanism has had more importance since 1980s in water pollution, noise and vibration, waste materials, human wastes, and radioactive pollution. However, in sea pollution, policy and standard rather than treatment technology or method of measurement and analysis has been considered a more important one in 1990s. Analyzing the studies on general remarks, it tell us that the paper on environmental act, which were frequently conducted, accounted for 33.3% until 1979, while the papers on the environmental policy, in which the highest interest was kept, accounted 34.6% in 1990s. This study concludes that most papers had examined the survey on status and evaluation of pollution degree before 1980, while studies on solving the problems of environmental pollution have had more importance in the 1980s and 1990s. Therefore, in the future, more studies should be conducted actively on policy development to solve the problems of environment pollution as well as on encouragement of environmental consciousness.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.575-593
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• 2012

This paper briefly introduces the scope and objectives of SKB Task 8, which is an international cooperative research project. In addition, the hydraulic behaviors of bentonite buffer focusing on the interactions between bentonite and a rock mass with a joint were investigated using TOUGH2 code as part of a sub-mission of Task 8a. The effects of a rock joint and high capillary pressure of bentonite on the re-saturation properties and pressure distribution in a buffer were identified and successfully incorporated in the TOUGH2 code. Based on the numerical results, it was found that the speed of re-saturation in bentonite surrounded by a rock mass with a joint is 2.5 to 12 times faster than that in a condition without a rock joint, while the degree of saturation in the lower part of the buffer material is generally higher than in the upper part in both the cases of with and without a joint. It can be anticipated that the results obtained from this study can be applied to an estimation of the full saturation time and a determination of optimum thickness with regard to the design of the bentonite buffer in a high level waste disposal system.

• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.218-231
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• 2005

This paper reviews the engineering approach needed to support humans during their long-term missions in space. This approach includes closed plant production systems under microgravity or low pressure, mass recycling, air revitalization, water purification, waste management, elimination of trace contaminants, lighting, and nutrient delivery systems in controlled ecological life support system (CELSS). Requirements of crops f3r space use are high production, edibility, digestibility, many culinary uses, capability of automation, short stems, and high transpiration. Low pressure on Mars is considered to be a major obstacle for the design of greenhouses fer crop production. However interest in Mars inflatable greenhouse applicable to planetary surface has increased. Structure, internal pressure, material, method of lighting, and shielding are principal design parameters for the inflatable greenhouse. The inflatable greenhouse operating at low pressure can reduce the structural mass and atmosphere leakage rate. Plants growing at reduced pressure show an increasing transpiration rates and a high water loss. Vapor pressure increases as moisture is added to the air through transpiration or evaporation from leaks in the hydroponic system. Fluctuations in vapor pressure will significantly influence total pressure in a closed system. Thus hydroponic systems should be as tight as possible to reduce the quantity of water that evaporates from leaks. And the environmental control system to maintain high relative humidity at low pressure should be developed. The essence of technologies associated with CELSS can support human lift even at extremely harsh conditions such as in deserts, polar regions, and under the ocean on Earth as well as in space.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.7
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• pp.283-292
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• 2013

In order to ensure high performance, all the servers in an existing server cluster are always On regardless of number of real-time requests. They ensure QoS, but waste server power if some of them are idle. To save energy consumed by servers, the server power mode control was developed by shutdowning a server when a server is not needed. There are two types of server power mode control depending on when a server is actually turned off if the server is selected to be off: static or dynamic. In a static mode, the server power is actually turned off after a fixed time delay from the time of the server selection. In a dynamic mode, server power is actually turned off if all the services served in the server are done. This corresponds to a turn off after a variable time delay. The static mdoe has disadvantages. It takes much time to find an optimal shutdown time manually through repeated experiments. In this paper, we propose a dynamic shutdown method to overcome the disadvantages of static shutdown. The proposed method allows to guarantee user QoS with good power-saving because it automatically approaches an optimal shutdown time. We performed experiments using 30 PCs cluster. Experimental results show that the proposed dynamic shutdown method is almost same as the best static shutdown in terms of power saving, but better than the best static shutdown in terms of QoS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.595-604
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• 2009

The HCCA reserves the channel resources based on the mean data rate in IEEE 802.11e. It may cause either the waste of channel resource or the increase of transmission delay at MAC layer if the frame size is rapidly varied when a compressed mode video codec such as MPEG video is used. To solve these problems, it is developed that the packet scheduler allocates the wireless resource adaptation by according to the packet size. However, it is difficult to perform the admission control because of the difficulty with calculating the available resources. In this paper, we propose a CAC mechanism to solve the problem that may not satisfy the QoS by increasing traffic load in case of using EDCA. Especially, the proposed CAC mechanism calculates the EB of TSs using the traffic information transmitted by the application layer and the number of average transmission according to the wireless channel environment, and then determines the admission of the TS based on the EB. According to the simulation results of the proposed CAC mechanism, it admitted the TSs under the loads which are satisfied within the delay bound. Therefore, the proposed mechanism guarantees QoS of streaming services effectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.816-822
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• 1997

The immobilization of a microorganism has been rapidly progressed with the development of biotechnology in recent years. Although it has been used as a tool to isolate products from biological media in various areas, it has not yet been practiced in the treatment of waste water. In this paper, we suggest a possibility to apply the immobilization technique In the recirculating aquaculture system. We examined the ability of $NH_4^+$ removal by nitrifier consortium immobilized in $Ba^{++}-alginate$, k-carrageenan and agar bead at the concentration of 50 g/L, respectively. In order to use the immobilized nitrifier consortium as media in the fludized bed reactor, the strength of bead was measured. $Ba^{++}-alginate$ as a support material showed higher strength of bead. Also, the nitrifier consortium immobilized in $Ba^{++}-alginate$ showed higher nitrification activity that could remove 20 mg/L ammonium ion than those immobilized in other two support materials, carrageenan and agar. The immobilized nitrifier consortium showed better nitrification activity than free nitrifier consortium.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.3
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• pp.74-90
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• 2010

The objectives of this paper are to introduce the GIS based resource circulation information, and to identify additional(or potential) industrial symbiosis based on existing industrial symbiosis and linkage-pair of industry by material. The resource circulation information contains information of the reuse of materials, water, and energy for all manufacturing companies in Ulsan Metropolitan City. The information can further be classified into the three steps -- input information(raw materials), flow information (products), and output information (by-products). The survey data from 3,768 industries and institutions in Ulsan Metropolitan area were collected and built into the GIS to analyze the mechanism of the industrial symbiosis. The results of this study strongly suggest that there are some additional industrial symbioses using by-products(materials, steam, waste water) and further efforts should be given to make them more effective. We expect that the methodology of building the resource circulation information of this study can be helpful to other local governments that try to build similar system.

• Environmental and Resource Economics Review
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• v.17 no.1
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• pp.165-196
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• 2008

This paper reports a quantitative meta analysis of the economic impacts of localized noxious and contaminated sites. Using either hedonic property value or stated preference methods, economists have studied the effects of contamination or noxious activities, or the benefits realized from their elimination, on real estate prices at more than 40 sites. In support of wise public and private investments in environmental quality, most of these studies aim to inform decision makers about the benefits of remediation and cleanup. Their results vary considerably, but there has been no previous systematic effort to analyze the differences and identify shared insights. This study uses established methods of meta analysis to identify points of agreement and differences in this body of literature. The studies are characterized by the type of site, modeling approach, geographic extent of impacts, data features, and other key factors that underlie their value estimates. The impact estimates are normalized as proportional effects on property values. This study attempts to discover whether the estimated economic impacts of contamination or noxious activity differ according to these characteristics of the studies, and whether anything general can be said about the economic consequences of site contamination and remediation. Bivariate, multivariate, and logit techniques are applied to the data. The results suggest that the property value is the most sensitive to water base contamination, published case studies result in systematically greater environmental value than those in unpublished reports, and real estate markets show responses to environmental condition changes.