• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.245-252
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• 2017

Recently, structures such as large retailers, outlets and warehouses have been increasing in accordance with changes in consumption patterns. Since these structures include ultra-flat slab members, they are thoroughly managed to control slab cracking by the plastic and drying shrinkage. In order to control the cracking of the slab member, a chemical crack reduction method is used. In particular, the use of the shrinkage reducing agent has been examined. However, domestic research results are limited. In this study, the shrinkage properties of concrete using shrinkage reducing agent and the drying shrinkage properties according to the mixing factors were investigated. The performance of domestic shrinkage reducing agent was appeared similar to that of overseas high-grade shrinkage reducing agent. As the shrinkage reducing agent usage increased, the drying shrinkage reduction effect increased. At the age of 100 days, the dry shrinkage rate of specimen with the shrinkage reducing agent of 1.5%was shown about half that of the specimen without the shrinkage reducing agent. The shrinkage reducing agent was gound to have no specific performance change for the use of the admixture.

• Korean Journal of Construction Engineering and Management
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• v.10 no.5
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• pp.67-75
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• 2009

While the trend of all industries recently lies in combination, construction industry is much interested in enhancing efficiency and competitiveness in the aspect of site control by adopting RFID. Though RFID has been applied to diverse areas thus far, it cannot be easily applied to construction industry due to diverse physical, chemical and use-environmental properties of construction materials. Furthermore, it is rarely applied to the site because of many problems in its application. It is required to prepare RFID code issuance and system that can systematically control the code as well as to research the standardization of frequency, specification, protocol, package method, recognition method, etc in order to apply RFID to construction industry. In this research, RFID code issuance and management program are proposed as a part of program research to apply RFID. Furthermore, the restricted matters of existing RFID tag are drawn to produce pilot product of RFID tag that can solve it so as to perform site application test. According to the experiment, effective recognition distance varies depending on material/environmental property and control efficiency changes depending on attachment method and application method. Thus, preparing diverse restrictive factors and solutions by systematically analyzing control method(medium, process) of current architecture materials and applying it to construction site can be the way to successfully apply RFID.

• Journal of Environmental Health Sciences
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• v.3 no.1
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• pp.27-44
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• 1976

This study was carried out to evaluate the harmful factors in working environments and to investigate the labor productivity after improvement of environments, surveying 93 industrial establishments of 10 industries located in Youngdeungpo industrial area in Seoul. The results obtained were as follows: 1) The highest noise level of 125dB(A) was indicated at the rolling process of transport equipment manufacturing industry. 2) The best illumination level was shown in precise machinery industry and the worst was indicated in rubber products, metallic products and transport equipment manufacturing industries. 3) Thermal conditions were above threshold limit value (TLV) at more than two processes of all industries except printing industry. 4) The highest dust concentration was determined in textile and wearing manufacturing industry. 5) Organic solvents were detected at 52 processes in 93 industrial establishments and 33 processes of them showed higher than TLV. The results about harmful chemicals were as follows: a) sulfur dioxide ($SO_2$)was determined higher than TLV on welding process of metallic product manufacturing industry and heat treatment process of transport equipment manufacturing industry. b) Carbon monoxide (CO) concentration was 700ppm at heat treatment process of transport equipment manufacturing industry, indicating 14 times of TLV. c) vinylchloride concentration in the air of PVC raw material mixing process and PVC preparation process of chemical product manufacturing industry was determined higher than TLV. d) Hydrochloride (HCl) concentration in the air of wire expanding process of transport equipment manufacturing industry was determined higher than TLV. 7) Higher values of lead concentration than TLV were determined at lead welding metallic product manufacturing industry and type planting process of process of printing industry, $1.8mg/m^3$ and $0.3mg/m^3$ respectively. 9) 22, 968 of 52, 855 workers (i.e. 43.5%) in 93 industries were exposed to various harmful agents. 10) It was found that the improvement of illumination in electric apparatus manufacturing industry (from 20~40 lux to 420 lux) resulted in an increase in productivity of 6.5% per capita and a decrease in faulty products of 19%. 11) Improvement of environments using local exhaust ventilation system resulted in a decrease of harmful substances lower than TLV and an increase in productivity of 11.4%. 12) Improvement of shovelling tools based on ergonomics resulted in a reduction in energy expenditure of 25.3% and an increase in productivity of 32.2% per capita.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.261-265
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• 2003

In order to examine the difference in processing quality of potato tubers among localities, chemical properties of soils were analyzed and climatic conditions were investigated. Potatoes (Solanum tuberosum L.) were grown at seven localities of Korea during two years from 1994 to 1995. Soil samples and tubers were obtained from 2 to 3 commercial farms per locality with 10 days interval from 70 days before harvesting. As the result of that, higher correlation in processing quality was found with organic material content among soil conditions. On the climatic conditions, minimum temperature and sunshine hours during the period from 30 to 11 days before harvesting exhibited highly significant negative correlations with all quality parameters except reducing sugar content. Additionally, regression equations based on the observed level of these factors showed the relatively high coefficients of determination for dry matter content and chip color. To produce higher quality potatoes for processing, therefore, climatic conditions such as minimum temperature and sunshine hour and soil condition such as organic matter content have to be considered before the selection of areas or fields.

• Journal of Conservation Science
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• v.28 no.4
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• pp.343-351
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• 2012

Excavated archaeological iron objects are prevented from being corroded going through desalination which slow down being corroded. However archaeological iron objects are liable to be corroded due to the high ionization tendency even though they are stored in environment restricted from corrosion factors. Iron objects could be deteriorated more than just excavated. Therefore this study investigated about the characteristic of re-corrosion and the effect on objects. In study, archaeological iron nails in storage for 4 years after conservation treatments were tested. Optical microscopy and X-ray photography for appearance, XRD, SEM-EDS, Raman spectroscopy for chemical composition, IC for chloride ions concentration inside iron nails were used. As results, iron nails carried out conservation treatments measured a high concentration of chloride ions after the long storage period. The form of objects were not in good condition such as broken or destroyed when the high chloride ions concentration was detected. In addition, the yellow and red powdery corrosion product were detected on the boundary between corrosion products and substrates and they were identified as akaganeite which is symptom of active corrosion.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.49-56
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• 2014

It is important to keep stable effluent water quality and minimize operation cost in biological wastewater treatment plant. However, the optimal operation is difficult because of the change of influent flow rate and concentrations, the nonlinear dynamics of microbiology growth rate and other environmental factors. Therefore, many wastewater treatment plants are operated for much more redundant oxygen or chemical dosing than the necessary. In this study, the optimal control scheme for dissolved oxygen (DO) is suggested to prevent over-aeration and the reduction of the electric cost in plant operation while maintaining the dissolved oxygen (DO) concentration for the metabolism of microorganisms in oxic reactor. For optimal control, The oxygen uptake rate (OUR) is realtime measured for the identification of influent characterization and the identification of microorganisms' oxygen requirement in oxic reactor. Optimal DO seT-Point needed for the microorganism is suggested based on real time measurement of oxygen uptake of microorganism and the control of air blower. Therefore, both stable effluent quality and minimization of electric cost are satisfied with a suggested optimal setpoint decision system by providing the necessary oxygen supply requirement to the microorganisms coping with the variations of influent loading.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.1 no.1
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• pp.28-44
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• 1998

This study was conducted to suggest the ecological restoration strategies for the disturbed landscapes by theoretical study. Especially, it is aimed to suggest three objectives for restoration by using native plants ; (1) prevention or reduction of wind and water erosion, (2) provision of food and cover for variety of animal species, (3) improvement of the visual or aesthetic quality of disturbed sites. The main results were summarized as follows. 1. Cooperation between restoration ecologists and restoration practitioners is needed to delineate a scientific approach to restoration ; (1) Being aware of published literature that describes similar work and/or establish general principles. (2) Preparedness to carry out proper experiments to test ideas. (3) Preparedness to monitor fundamental parameters in a restoration scheme. (4) Providing information about the behavior of species. (5) Publish results. 2. There are three models of succession in theories of plant succession. The tolerance and facilitation models were recommended to ecological restoration. The inhibition model applies in most secondary succession, but the actual species which are introduced first may inhibit the germination and growth of slower-growing species, or they may prevent the growth of other species whose propagules arrive later. 3. The objectives of erosion control, wildlife habitat provision, and visual quality improvement are not mutually exclusive. However, many revegetation practices in the past have emphasized one of these aspects at the expense of the others. 4. A native plant community can be the model of ecological restoration. By stylization/abstraction of native plant community, trying to learn the most essential characteristics of community types - environmental factors ; dominant, prevalent, and "visual essence" species composition - in order to use such information in restoration. 5. After developing mass/spaces plan, match plant communities to the mass/space plan. In utilizing community grouping, there needs aesthetic ability to understand design elements. 6. Several hydrophytes such as Pennisetum saccharifluous, Themeda triandra, Cirsium pendulum show relatively good germination rates. In case of mesophytes and xerophytes, Arundinella hina, Artemisia princeps, Oenothera odorata and legumes seem to have quick-germinating abilities at barren sites. Pinus thunbergii, Rhus chinensis, Evodia daniellii, Alnus firma and Albizzia julibrissin can be considered as "late succession" woody plants because they show low germinating rates and slow growing habitat. 7. The seeds used for restoration should be collected within a certain radius of where it will be planted. Consideration in genetic issues in the collection and use of germplasm can increase the odds for successful restoration efforts. 8. The useful model in the "drift" pattern occurs so abundantly in naturally evolving landscapes. As one species diminishes in density, a second or third species are increased. Thus, dynamic interactions between species are created. Careful using of "drift phenomenon" in planting was recommended. 9. Virtually no stand of vegetation today is immune from the introduction and/or spreading of exotic species. Therefore, the perpetuation of a restored sites requires conscious monitoring and management. Thus, management would be the most important process in ecological restoration. 10. In order to keep the sites "natural", alternative management strategies would be applied in management ; Atenative management strategies are decelerating successional process, accelerating successional processes or modifying species composition. As management tools, mechanical, chemical, biological or environmental factor manipulation, e.g., fire could be used.

• Economic and Environmental Geology
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• v.35 no.3
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• pp.285-297
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• 2002

This study was carried out to prove the factor properties of the soil affected by a forest fire through the physical and chemical analysis and the data from the conclusion of those analysis are applied to the development of technics that reduces a forest fire-induced 2nd damage. The forest fire was in December 2000 at Gangreung city and Donghae city, Gangwon provinces, Korea. Soil samples were collected at upper layers (0-5 cm) and bottom layers (5-40 cm) in November 2001 from the burned and control sites. Values of pH in burned soils of the upper layers affected by forest fire are higher than those in control soils. Both the fragments of fire-burned plant and differences of geological properties are resulted in a class of soil. Contents of organic matters in burned soils are higher than those in control soils, exceptionally the contents of organic matters in burned soils that contain coaly shale are lower than those in control soils. Weathering indices in burned soils are higher than those in control soils and it concerned with loss of soil. Iron ions Fe(Fe$^{2+}$ or Fe$^{3+}$) are easily extracted from the burned soils by rainfall, but Mn ions are straightly exist in the burned soils by physiochemical adsorption of colloid. Through the sequential extraction in the burned soils and control soils, we are certificate the extraction of Fe ions and the disturbance of Mn ions from the burned soils. As a consequence of factor analysis in burned soil and control soil, we are certificate that the influence of forest fire results in a disturbance of positive correlation factors.

• Applied Biological Chemistry
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• v.49 no.3
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• pp.209-214
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• 2006

Various varieties of mulberry fruit and wines were investigated to determine their chemical properties and fermentation characteristics. Mulberry wines were manufactured with 'Cheongnosang', 'Cheonhyunosang', 'Deokcheonsang', 'Hwachosipmunja', 'Hwanyoupdaeyoup', 'Jasan', 'Mansaengbaeckpinosang', 'Palcheongsipyung', 'Sabangso' and 'Susungppong'. The factors for wine fermentation and quality such as soluble solids, polyphenol and organic acids were analyzed. The contents of soluble solid, reducing sugar and polyphenol, which were affected significantly by each other, were higher for 'Hwanyoupdaeyoup', 'Jasan' and 'Palcheongsipyung' mulberry than other varieties. Organic acids such as citric, malic, succinic and acetic acid were detected in the mulberry fruits. 'Palcheongsipyung' mulberry fruit had a higher content of souble solids $(14.6^{\circ}Brix)$ and polyphenol compounds (2.15 mg/ml). After fermentation, 'Palcheongsipyung' mulberry wine showed the lowest acetic acid in 3.23 mg/ml and the highest citric acid in 12.3 mg/ml. From these results, 'Palcheongsipyung' mulberry fruit was the most suitable for the fermentation of mulberry wine.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.295-306
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• 2004

Spatial patterns in the macrobenthic community structure in the inter- and subtidal zones in front of the Iwon Dike and environmental variables were examined in August 2001, In total, 156 macrobenthic species(123 intertidal species and 90 subtidal species) were recorded during this study, predominately polychaetes $(40{\%})$, bivalves $(22{\%})$, and crustaceans $(22{\%})$. Polychaetes made up less than $40{\%}$ of the intertidal communitr, but more than $50{\%}$ of the subtidal community. The mean density during this study was $1,456ind./m^{2}.$ Multivariate analysis (multidimensional scaling) revealed significant differences in community structure among four regions: near the Iwon dike (B1), the high and middle intertidal zone (B2), low intertidal zone (Al), and subtidal zone (A2). The number of species, total density, and diversity (H') varied significantly among the four regions. The distribution of macrobenthic community was affected by environmental variables, such as ${\%}$ silt/clay content, total sulfide, lose of ignition, and chemical oxygen demand. These environmental variables were negatively correlated with the dominant species (Nephtys polybranchia, Umbonium thomasi, and Scoloplos armiger) in the intertidal area, but positively correlated with the dominant species (Lumbrineris cruzensis, Notomastus latericeus, and Moerella sp.) in the subtidal area. Environmental variables $({\%}\;silt/clay content and total sulfide)$ were positively correlated with the dominant species (Heteromastus filiformis) in region Bl, but negatively correlated with the dominant species (Umbonium thomasi and Scoloplos koreanus) in region B2. Amphipods Urothoe spp. and Monoculodes koreanus were the dominant species in region Al. Umbonium thomasi, the dominant species in region B2, was not found in regions Bl or Al. We suggest that the inter-specific competition for territory and exposure to seawater may be important factors controlling the macrobenthic community structure in the inter- and subtidal zones in front of the Iwon Dike.