• Analytical Science and Technology
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• v.28 no.6
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• pp.460-466
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• 2015

An isotope dilution liquid chromatography tandem mass spectrometry was developed as a primary method for the quantitative analysis of cholesterol in infant formula. Cholesterol-d₄ was used as an internal standard and spiked into the infant formula sample. In order to release cholesterol out of cholesteryl ester, which is cholesterol bound to fatty acids in infant formula, saponification was carried out. Saponification conditions were optimized with heating temperature, reaction time and the concentration of KOH. The optimum conditions were as follows; heating temperature was 70 ℃, reaction time was 180 min and the concentration of KOH was 0.8 mL of 8 M KOH for about 0.1 g infant formula sample. Extraction of cholesterol out of sample solution was carried out with hexane uisng liquid-liquid extraction. Chromatographic analysis was carried out using Phenomenex Kinetex C₁₈ column. Mobile phase was 0.1% acetic acid in methanol/water (v/v, 99/1) and flow rate was 0.3 mL/min. Cholesterol and cholesterol-d₄ were monitored at mass transfer m/z 369/259 and 373/263 respectively. Reproducibility of the method was evaluated to be 0.23% of the measurement result. The expanded uncertainty of the measurement result of cholesterol in infant formula was approximately 1.9% at a 95% confidence level. NIST standard reference material having certified values of cholesterol in infant formula, was analyzed in order to verify this method. The ID-LC/MS/MS results were well agreed with the certified values of NIST SRM within the uncertainty.

• Journal of Environmental Impact Assessment
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• v.19 no.5
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• pp.475-481
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• 2010

Lots of pollutants typically originating from urban transportation are accumulating on the paved surfaces during dry periods and are washed-off directly to the river during a storm. Also, paved surfaces are contributing to increase in peak flows and volume of stormwater flows. These are the main reasons why the water quality of rivers and lakes remain polluted and still below standards. Currently, several management practices are being applied in developed countries but the design standards are still lacking. This research was conducted to develop a treatment technology that can be useful to address the problems concerning runoff quality and quantity. A lab scale infiltration device consisting of a pretreatment tank and media zone was designed and tested for various flow regimes characterizing the low, average and high intensity rainfall. Based on the experiments, the high intensity flow resulted to increase in outflow event mean concentration (EMC) of pollutants, about twice as much as the average outflow EMC. However, 78 to 88% of the total suspended solids were captured and retained in the pretreatment tank because of sedimentation. The removal of heavy metals such as zinc and lead was greatly affected by the vertical placement of woodchip layer prior to the media zone. It was observed that the high carbon content (almost 50%) in the woodchip provided opportunity for enhancing its uptake of metal by adsorption. The findings implied that the reduction of pollutants can be greatly achieved by means of proper pretreatment to allow for settling of particles with a combination of using high carbon source media like woodchip and a geotextile mat to reduce the flow before filtering into the media zone and finally discharging to the drainage system.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.3
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• pp.95-102
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• 2015

This study conducted the survey on the resources of traditional villages based on AHP in the subjects with the specialists in Korea and China to seek the resource evaluation standards to apply the preservation and development of traditional villages, and the differences of the importance on the resources among the specialists in both countries. We classified three levels of evaluation items to aim the deductions of the importance and priority in the resources of traditional villages. Upon the analysis results, natural resources were important in the level 1; environmental, historical, facility resources were important in the level 2; and the factors such as air, topography, traditional houses, agricultural landscape, shared community facilities, interchanges between urban and rural areas, family activities, and so on were important in the level 3. The factors that both Korean and Chinese groups evaluated as the most important ones were the same. In terms of overall importance by evaluation items, the factors such as air, water quality, noise, traditional houses, topography, shared community facilities, and so on were rated as relatively important in both Korean and Chinese groups. That is, the traditional villages have the necessity to preserve the cultural resources like their duties, however, it is required to control the natural environment with good quality preferentially. This study results can compare the importance on the resources of traditional village between Korea and China. Moreover, with calculation of the priority and scores for the preservation and management of traditional villages, they are expected to be used as the tool to apply the quantitative data in the evaluation process of traditional village resources in both countries.

• Economic and Environmental Geology
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• v.41 no.4
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• pp.383-392
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• 2008

This study aims to evaluate the mechanical-chemical stability of used coal ash blocks, for improving fishing grounds. The surface of weathered ash blocks in seawater showed a decrease in the Ca and an increase in the Mg contents, compared to that of fresh blocks. This result reflects the substitution of Ca by Mg in seawater. The compressive strengths of ash blocks submerged into seawater during 12 months ranged from 235.23 to $447.43\;kgf/cm^2$; this is higher than the standard strength of wave-absorbing blocks($180\;kgf/cm^2)$ that are used for harbor construction. In addition, the compressive strength of ash blocks tends to increase with increasing installation time in seawater. The result of leaching experiments on coal ash blocks by Korean Standard Leaching Test(KSLT) method showed that leached concentrations of most metals except Cr(that leached up to 50 ppb, approaching standard concentration) do not exceed the seawater quality standards. A long-term(112 days) heavy metal leaching test to analyze seawater without mixing-dilution also showed that the concentrations of leached heavy metals, except for Cu, under anaerobic conditions do not exceed the seawater quality standards. Accordingly, the use of coal ash blocks in marine environments appears to be safe from chemical and mechanical factors that decrease the efficiency of concrete. Also, leaching concentration of Cu seems to be stable by decrease of leaching concentration due to dilution of seawater.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.599-615
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• 2022

In order to excavate underground tunnel most safely such as Han river, the slurry shield TBM method is applied to cope with face of high water pressure for many metro projects. In downtown subway project most of excavated soil is discharged externally whereas in road construction excavated soil is used as filling materials so it becomes important factor for success of the project. After excavated soil, weathered rock and soft rock are discharged with bentonite through discharge pipe to slurry treatment plant then those soils are separated in separation plant according to those size. Fine grained soil has been discarded together with filter cake but it is not toxic and can be mixed with coarse aggregate in proper ratio so this study is performed to find use of qualified filling material to meet quality standard. Therefore, in this study, legal standards and quality standards for the utilization of excavated soil of the slurry shield TBM method were examined and test was conducted to derive recycling way for filter cake and aggregate. And a plan for using it as a filling material for road construction was derived. Because bentonite is a clay composed of montmorillonite, and the excavated soil in the tunnel is also non-toxic, disposal of this material can waste social cost so it is expected to be helpful in the underground space development project that carries out the TBM project by recycling it as a valuable resource.

• Membrane and Water Treatment
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• v.11 no.2
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• pp.123-130
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• 2020

Submerged Membrane bioreactor (SMBR) is one of the last techniques that allow a high quality of treated industrial effluents by coupling biological treatment and membrane separation. Thus, this research was an effort to evaluate performance of a SMBR treating a model textile wastewater (MTWW). Different SMBR operating parameters like mixed liquor suspended solids (MLSS) and Dissolved oxygen concentration, hydraulic retention time (HRT), and nutrients addition (N and P) have been investigated. MTWW (influent to the SMBR) was generated using the reactive azo-dye, Novacron blue FNG (100mg/L feed concentration). Results of MTWW treatment using SMBR under optimal operating conditions (MLSS, 4.2-13.3g/L; HRT, 4 days; pH, 6.9-7.2; conductivity, 400-900 μS/cm and temperature, 19.4-22.2 ℃) showed that COD and blue colour treatment performances are between 94-98% and 30-80%, respectively. It is concluded that SMBR can be used in large scale textile wastewater treatment plants to improve effluent quality in order to meet effluent discharge standards.

• Journal of Korean Home Economics Education Association
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• v.29 no.3
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• pp.161-183
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• 2017

The purpose of this study is to develop a concept map in a visual instructional strategy so that meaningful learning can be done by structuring knowledge in the section of eco-friendly clothing life and reform clothes. For this purpose, ten textbooks for the 2009 revised were analyzed, and 10 sub-area were selected to develop the concept map. The development was done by using Cmap Tools V6.02 and the study process has progressed content analysis, concept extraction, and concept map development. The analysis process and results of this study are as follows. First, in the course of setting standards, the analytical standards were set for the 2007 revision and 2009 revision curriculum achievement standards. Second, in the process of content analysis and concept extracting, through the analysis of textbooks, 'clothing selection and purchase', 'clothing care and management' and 'clothing reuse and eco-friendly'. The concept was extracted by subdividing on the basis of general and comprehensive core concepts. Third, the development process of concept map was developed and revised based on the extracted concepts, and the concept map developed was the 'clothing purchase plan', 'points to consider when buying clothing' 'quality', 'handle with care', 'classify laundry', 'remove stain', 'water washing', 'repair clothing', 'reform clothing', 'eco-friendly clothing life'.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.675-684
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• 2020

To prevent safety accidents caused by aging pipe infrastructure and to maintain water quality, construction projects for water and sewage pipes are actively conducted across Korea. This study analyzed the criteria situations, site survey details, and regulation revisions related to the calculation of construction cost standards for pipe laying and joining work. The analysis showed that the major causes for revision are the unclear construction scope, limitations in implementing some pipe materials due to installation facility types, workforce focused on ordinary labor, limitations of manual laying work, and the lack of tool hire cost and machine expense-calculation criteria. Field studies were conducted to categorize the pipes according to their features, in addition to identifying the use of lifting heavy equipment and light equipment. In addition, excavation and testing work conducted in connection to pipe laying, as well as the use of skilled labor, were investigated. The current study clarified the work scope through new common items, provides an organization based on the pipe material, adjusted the workforce ratio to focus more on skilled labor, and developed grounds for calculating machine expenses. These revisions were estimated to save approximately 1.28% of the construction costs in each project according to an analysis of the construction cost impact study. truction costs in each project, according to an analysis of construction cost impact study.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.76-83
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• 2017

Biogas, combine with ever-increasing natural gas demand, has been on the center stage in South Korea for the early part of twenty first century in an effort to reduce the emission of global warming gases. With the passage of legal system of City Gas Business Law in 2014, the biogas has its place of production and distribution to consumers. However, it has a room for its technological improvements in terms of enrichment, by separating carbon dioxide and removing impurities efficiently. For these improvements, four different methane enrichment processes were tested in this study; membrane separation, water absorption, Chemical Absorption and Adsorption. A variety of operation scenarios were applied to the processes and the best practices were drawn out. The optimum process was selected based on case study results. Methane produced in this study showed 97% purity and 98% recovery rate, which meets the requirements of the City Gas quality standards.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.449-455
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• 2009

In Hansan Geojeman area, 2,050 ha of shellfish growing area has been designated as shellfish production area for export. The main shellfish species from the designated area is oysters. For the sanitary management of the designated area established in Hansan Geojeman area, bacteriological examination of sea water and shellfish at the sampling stations inside and outside of the designated area were performed from January 2006 to December 2008. The range of fecal coliform of 756 sea water samples at 21 stations located in the designated area were <1.8~>1,600 MPN/100mL. And the range of geometric mean and the estimated 90th percentile of fecal coliform were 1.8~2.9 and 2.7~15.8 MPN/100mL, respectively. Sanitary conditions of the current designated area in Hansan Geojeman meets the required standards of the Fisheries Product Quality Control and National Shellfish Sanitation Program (NSSP, USA) criteria for the approved area. Also, the sanitary status of the shellfish harvested from the designated area met the Korean Shellfish Sanitation Program (KSSP) fecal coliform criterion (<230 MPN/100g). And the human pathogen such as Salmonella spp. and Shigella spp. were not detected from the examined shellfish samples.