• KSBB Journal
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• v.17 no.1
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• pp.80-87
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• 2002

Laboratory scale aerobicfanaerobic biofilm reactor was used for simultaneous and stable removal of organics, N and P components to investigate optimum design and operation parameters and to analyze the microbial distribution and consortium structure of nitrification and denitrification bacteria in aerobic and anaerobic biofilm systems. The biofilm reactor was successfully operated for 143 days to show $COD_{cr},\;BOD_5$, SS removal efficiencies of 88, 88, and 97%, respectively. During the experiment period, almost complete nitrification efficiency of 96% was achieved. Denitrification efficiency was about 45% without addition of any external carbon sources. In case of total phosphorus removal, 74% of the inlet phosphorus was removed. Fluorescence in situ hybridization (FISH) results showed that most of the ammonia oxidizing bacteria in the aerobic nitrification zone was found to be Nitrosomonas species while Nitrospira was the representative nitrite oxidizing bacteria. For the denitrification, Rhodobacter, Rhodovulum, Roseebacter and Paracouus were the dominant denitrification bacteria which was 10 to 20% of the total bacteria in numbers.

• Korean Journal of Construction Engineering and Management
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• v.17 no.4
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• pp.12-19
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• 2016

Recently, The importance of modular construction method has increased by market environmental change. However, it's application in the actual project is restricted due to the lack of understanding of modularization and the absence of utilization system. To overcome this problem, this study propose the decision-making model for selecting modular or conventional (stick-built) construction method at early stage. First the needs of modular method in plant project is derived and the benefits and barriers of modular construction are analyzed through literature review. Based on this analysis, 6 decision-making factors covered project and modular characteristics are derived and the decision-making model is developed. Finally, 12 actual overseas project cases is evaluated by this model for verifying its applicability. This proposed model can provide the guideline to select the construction method in early stage for successful execution of plant project.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.44-53
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• 2005

In this paper, a improved moving object detection algorithm for stable performance of surveillance system in case of iterative moving in limited area and rapidly illuminance change in background scene is proposed. The proposed algorithm is that background scenes are sampled for initializing background image then the sampled fames are divided by block and sum of graylevel value for each block pixel was calculated, respectively. The initialization of background image is that background frame is respectively reconstructed with selecting only the maximum graylevel value and the minimum graylevel value of blocks located at same position between adjacent frames, then reference images of background are set by the reconstructed background images. Moving object detecting is that the current image frame is divided by block then sum of graylevel value for each block pixel is calculated. If the calculated value is out of graylevel range of the initialized two reference images, it is decided with moving objects block, otherwise it is decided background. The evaluated results is that the error rate of the proposed method is less than the error rate of the existing methods from $0.01{\%}$ to $20.33{\%}$ and the detection rate of the proposed method is better than the existing methods from $0.17{\%}\;to\;22.83{\%}$.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.106-111
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• 2008

Polypropylene (PP)/corn starch master batch (starch-MB)/silicate composites with different corn starch compositions of 10, 20, 30, 40 and 50 were prepared by melt compounding at $200^{\circ}C$, using lab scale Brabender mixer. The content of silicate was fixed at 5 wt%. The composition of starch-MB in composites was confirmed by the existence of hydroxy group and peak intensity in fourier-transform-infrared (FT-IR) spectrum. The thermal properties of the PP/starch-MB/silicate composites were investigated by differential scanning calorimetry (DSC), and thermogravimetric analyzer (TGA). There was no district change in melting temperature, and TGA curve indicates a decrease in degradation temperature with the increase of starch-MB content. The silicate dispersion of the composites was measured by X-ray diffraction (XRD) and transmission electron microscope (TEM). The degree of silicate dispersion in PP/starch-MB/silicate composites depended on the content of starch-MB. There was detectable change in d-spacing and peak intensity of the composite when the content of starch-MB was higher than 20 wt%. The rheological behavior of the composites was explained by both shear thinning effect and elastic property with the starch-MB amount. These effects were remarkable when the content of starch-MB was higher than 20 wt%. These were confirmed by an oscillatory viscometer at $200^{\circ}C$.

• KDI Journal of Economic Policy
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• v.14 no.2
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• pp.3-27
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• 1992

In 1988, the government provided to the low income people 34.1% of the stocks of Pohang Iron & Steel Company through the People's Share Program of Privatization for the first time, and then in 1989 21% of the share of the Korea Electric Power Corporation were also provided to the low income classes through the same way. The purpose of the People's Share Program was known to be to support the low income classes through participating the profit of public enterprises, and also to expand the capital market through the diversification of stock holding structure. Initially, the government planned that the government share of enterprises such as the Citizens National Bank, the Korea Telecommunication Authority would be sold to the low income classes through the People's Share Program step by step. The income support policy, however, was no longer driven after 1989 when the overall stock prices started to decline. In this paper we tried to measure the effect of the privatization scheme of the public enterprises through the People's Share Program. The problems of the People's Share Program of the Pohang Iron & Steel Commpany and the Korea Electric Power Corperation were also identified. Several implications of the privatization scheme of the public enterprise through the People's Share Program by stages were found. The People's Share Program was found to be a non-stable policy measure for the income support of low income classes. The efficiency impact of the privatization through the People's Share Program was found to be non-significant.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.294-301
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• 2008

This study was carried out to investigate the protective effects and detoxification of oriental herb extracts mixture (Saururus chinensis, Taraxacum platycarpum, Ulmus macrocarpa, Glycyrrhiza glabra, Rhynchosia nulubilis) on TCDD-induced oxidative stress. Thirty five male rats were divided into 5 groups: normal control group received saline; vehicle control group received DMSO and acetone; only TCDD-treated group received multiple intraperitoneal injection of TCDD ($100{\mu}g/kg$) and saline; post-treated group of OHEM (400 mg/kg/day) received oral administration for 5 weeks after TCDD treatment; and pre-treated group of OHEM (400 mg/kg/day) received oral administration for 6 weeks from 1 week before TCDD treatment. The elevated serum activities of alanine transaminase (AST), aspartate transaminase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and atherorganic index due to TCDD were significantly decreased by the treatment of OHEM (p<0.05); the pre-treatment of OHEM was especially effective. Hydropic lesions and cytoplasmic vacuolizations in the liver of TCDD-treated rats were inhibited by the treatment of OHEM. Also, OHEM treatment reduced edemas in small intestine villus of TCDD-treated rats. These results suggest that OHEM from various oriental herb extracts might be a useful protective and detoxification agent against TCDD.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.791-795
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• 1992

The limiting equivalent conductances of LiCl, NaCl, KCl and KBr have been obtained in water using conductometric method from 1 to 2000 bars at $25^{\circ}C$. From the limiting equivalent ionic conductances (obtained using TATB[Tetraphenyl Arsonium Tetraphenyl Borate]method) of $Li^+$, $Na^+$, $K^+$, $Cl^-$, and $Br^-$ ions and viscosity of water at given pressure, their Stokes radii have been calculated. From the corrected radii caliberated by Nightingale method and the crystallographic radii at a given pressure, the volume of hydration-shell surrounding ion was calculated and hydration numbers of $Li^+$, $Na^+$, $K^+$, $Cl^-$, and $Br^-$ ions were obtained. From the experimental results, it was found that the hydration number of $Li^+$, $Na^+$, $K^+$, $Cl^-$, and $Br^-$ ions slightly decreased with increasing pressure. This trend may be explained by Horne's suggestion[Advances in High Pressure Research]. Comparing results of this study with those of Nakahara's, the hydration numbers of $K^+$ and $Cl^-$ ions were almost twice as large as those of Nakahara's[Rev. Phys. Chem. Japan, 42, 12 (1972)]. By comparing the present results with those of Kollman's [J. Am. Chem. Soc., 113, 2481 (1991)], the hydration number obtained by applying TATB method and Nightingale method may be inferred to be reasonable.

• Journal of the Korean Chemical Society
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• v.56 no.3
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• pp.363-370
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• 2012

The purpose of the study was to classify scientific models in the seventh grade science textbooks of the 2007 revised science curriculum. The three chapters of 'three states of material', 'motion of molecule', and 'change of state and energy' were investigated. There were two types of the scientific model as 'mode of representation' and 'attribute of representation'. The mode of representation was composed of 'action model', 'analogical model', 'symbolic model', and 'theoretical model' and the attribute of representation was composed of 'static model' and 'dynamic model'. The results showed that the action model and the analogical model were used primarily in mode of representation. The dynamic model were widely used in attribute of representation. Area of matters dealt with conception of molecules and aimed for students to understand the arrangement and movement of molecule microscopically about macroscopic state in a daily life. Tis study could help to recognize the limitations of scientific models on current textbooks and offer more useful information in planning lessons and organizing textbooks for the future.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.976-980
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• 2010

A series of arylacetylene resins with siloxane units were synthesized by the condensation reactions of m-diethynylbenzene magnesium reagents with various $\alpha,\omega$-bis(chloro)dimethylsiloxanes. These resins are liquids and are miscible with common organic solvents at room temperature. The structures of the resins were characterized by FT-IR, $^1H$ NMR, $^{13}C$ NMR, $^{29}Si$ NMR, and gel permeation chromatography (GPC). The thermal behaviors of the resins were examined with differential scanning calorimetry (DSC). These resins have good processability. They can be thermally cross-linked through the ethynyl groups to produce cured resins. The thermal and thermooxidative stabilities of the cured resins were studied by thermogravimetric analysis (TGA). The cured resins possess high thermal and thermooxidative stability. Their decomposition occurs at above $500^{\circ}C$ in both $N_2$ and air. With increasing the length of siloxane units in the resins, the thermal stability of the cured resins decreases in $N_2$. When the cured resins were sintered above $1450^{\circ}C$ under argon, hard and glassy SiOC ceramics were obtained. These SiOC ceramics have the decomposition temperatures at 5% weight loss above $800^{\circ}C$ in air.

• Journal of the Korean Chemical Society
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• v.62 no.3
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• pp.203-213
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• 2018

The purpose of this study was to investigate the impact of student assessment activities on claim and evidence formation in argument-based inquiry (ABI) for high school students. The participants of the study were 166 grade 10 students from six different classes in the same high school. The experimental group (84 students) was taught Argument-Based Inquiry with students' self and peer assessment activities. The comparative group (82 students) was taught without the activities. Over one semester students participated in five ABI programs that we developed. According to the analysis of the claim and evidence from groups, the experimental group had a significantly higher mean score than the comparative group. The result of analysis of students' assessment in the experimental group, the frequency about accurate and sufficient evidence revealed to be high and students assessed whether peers' claims fit with the evidence and whether peers' explanations of the evidence's validity was sufficient. Students' answers in the survey and interviews showed that the students though they could improve the accuracy of their ideas, appropriateness of their evidence, and the method of presenting evidence based on the assessment results.