• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.350-363
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• 2009

Inter- and intra-specific differences in removal activities, filtering rates (FR) and production of feces-and pseudo-feces (PF) between a native freshwater bivalve in Korea, Anodonta woodiana Lea and Unio douglasiae Griffith et Pidgeon, were compared using a continuous removal of organic matters (CROM) system. The CROM system comprised five steps; input of polluted water, control of water flow, mussel treatment, analysis of water quality and discharge of clean water. The study was designed to compare the removal activity of organic matters between A. woodiana and U. douglasiae, and the intra-specific differences between density and length in A. woordiana. Results clearly indicate that two kinds of mussels had obvious removal activities of seston in the eutrophic reservoir. First, if both are similar in shell length, there were no significant inter-specific differences in removal activity between A. woordiana and U. douglasiae (P>0.5), but FRs of U. douglasiae was relatively high due to low ash-fee dry weight. Second, if both are same in animal density, the smaller mussels (1$\sim$2 years old) showed a higher filtering rate and production of feces- and pseudo-feces and less release of ammonium than the larger mussels. Third, if both are same in biomass, FRs and PF of mussels were higher in the low-density tank than the high-density tank, While the Concentration of $NH_4$-N and $PO_4$-P released WRS similar to each other (P>0.5). Therefore, these results suggest that CROM system using a young bivalve A. woordiana can be applied to control the nuisance seston in eutrophic lake system, if a relevant species and density were selected. Additional pilot tests to optimize the age and density of domestic bivalves were needed for the generalization of CROM operation.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.36-43
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• 2020

BACKGROUND: Wicheon watershed has the largest irrigation area among the mid-watershed of Nakdong river. However, no investigation of irrigation water quality has been conducted on the Wicheon watershed, which evaluates the effects on the soil quality and crop cultivation. Therefore, this study aims to provide various assessments of water quality of Wicheon watershed as the scientific basic data for efficient agricultural activities. METHODS AND RESULTS: Water sampling was performed in five locations of the first tributaries of Wicheon. Wicheon watershed showed clean water quality with very low organic matters and safe water quality from metals at all points of investigation. It was estimated that the natural chemical components of Wicheon watershed were originated from water-rock interaction in Gibbs diagram. All samples were concentrated in the type of Ca-HCO₃-Cl in the Piper diagram. The quality of irrigation water was evaluated with sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), and percent sodium (%Na). The values of these water quality indices were in the range of 0.37-0.67, -2.11--0.24, 41.13-84.52% and 11.28-21.84%, respectively, and were classified as good grades at all sites. CONCLUSION: The water quality of Wicheon watershed was very low in salt, indicating good irrigation water suitable for growing agricultural products. We hope that the results of this study will be used as the basic data for the cultivation of agricultural products and promotion of their excellence.

• Journal of Korean society of Dental Hygiene
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• v.8 no.4
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• pp.19-30
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• 2008

This study reached the following conclusions as a result of carrying out the questionnaire survey of self-descriptions for the satisfaction after the citizens of Daejon uses the dental clinics, in order to identify the factors of satisfaction to the medical services of such dental clinics to be utilized in the patient management by dental hygienists, provide the basic data to provide the medical services desired by patients. 1. 43.9% men responded to the facilities and 56.1% women to the atmosphere for the standards of selection of dental clinics by general characteristic, and the college graduates or more to the kindness (38.2%), high-school graduates (43.2%) and middle-school graduates (25.9%) or less to the close distance for the level of educational attainment (p=0.009), which was meant to have a statistical significance. 2. The execution of reservation system for the dental clinics showed 54.7%, the reserved time was observed upon the execution of such reservation system, the dental clinics where they practice such system were 40.6%, and the confirmation methods was done through the telephone with 62.5%. 3. The experience of fear upon the dental treatment showed 74.6%. The type of fear showed the machine sound (48.7%) for men and cry of others for women (70.8%) at the highest. 70% of those under 30 at the age responded to the sharp instruments at the highest. 83.3% of Yousung-gu showed the highest by responding to the cry of others for the residential areas. The statistically significant difference was shown in both the age and residential area (p=0.000). 4. Women showed higher in the distribution of gender for the sterilization of instruments for the external satisfaction of dental clinics(p=0.000) and those under 30 at the age showed the highest with 2.98${\pm}$0.95(p=0.001). Seo-gu (3.48${\pm}$0.77) was the highest for the residential area (p=0.000), and there was statistically significant differences in the gender, age and residential area. 5. Men showed higher satisfaction than women in the clean state and the statistically significant differences were shown (p=0.000) at the age as the high satisfaction was shown for those under 30 at the age (2.35${\pm}$0.79), those having the income not less than 10 million won and not more than 20 million won (2.43${\pm}$0.78), and Seo-gu (2.63 ${\pm}$0.69) for the residential area. 6. For the internal satisfaction of dental clinic by users for the medical services in the dental clinics, 61.1% women responded to no in the ability of solving the inconvenience in the service process, and showed low ability of solving the inconvenience from 30 at the age (26.2%) and by responding to Dong-gu (22.1%) for the residential area, showing statically significant differences(p=0.000). For the re-use of dental clinics, 46.6% men (p=0.043) for the gender, 24.3% under 30 at the age and 22.9% of Dong-gu for the residential area responded to the re-use, showing statistically significant differences for the gender and residential area (p=0.000). 7. The dissatisfaction showed a high rate of 69.5% for the satisfaction to the medical services of dental clinics. 46.2% men responded to the pain and women to the feeling of foreign substance for the reason of dissatisfaction while those under 30 at the age showed 55.6% for others, those between 50 and 59 41.7% for the feeling of foreign substance. 86.3% carried out the education for cautions after the treatments and most people turned out that they do not carry out the continuous health management of mouth as 20.5% responded to that they carry out such health management.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.400-420
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• 1998

We already know that it is very difficult to obtain an "isolated field" for direct bonding during the surgical exposure of unerupted teeth. The aim of this in-vitro study is to simulate the clinical situation of forced eruption and to evaluate the tensile strengths of preligatured button with several types of contamination which can happen during the surgical exposure of unerupted teeth. Four orthodontic direct bonding systems were used. ($Ortho-One^{TM}$, $Rely-a-Bond^{(R)}$, $Ortho-Two^{TM}$, Phase $II^{(R)}$) Each material was divided into four groups(n=20) : Group 1. (Control, no contamination), Group 2. (Rinse etching agent with saline instead of water), Group 3. (Blood contamination of etched surface for 30 seconds), Group 4. (Blood contamination of primed surface for 30 seconds) 320 bovine anterior permanent teeth were divided into the above mentioned 16 groups. Enamel surface was flattened and ground under water coolant. Pre-ligatured buttons were prepared to the same form. (Cut 0.25 ligature wire 10 cm in length. Twist the ligature wire 30 times clockwise. Mark the wire 15mm and 35mm points from button. Make a loop sticking two points together and twist the loop 6 times counterclockwise.) The bonded specimens were stored at $37^{\circ}C$ saline solution for 3 days. Then the tensile strength of each sample was measured with Instron universal testing machine, crosshead speed of 0.5mm/min. The following results were obtained: 1. As compared to control groups (Group 1) of each material, Rely-a-Bond had a significantly lower mean tensile strengths than other material. (p<0.01) 2. In Group 2. of Ortho-One and Rely-a-Bond, the mean tensile strengths decreased about 7.7% and 11.1%, respectively with statistical significances. (p<0.05) 3. In Group 2. of Ortho-Two and Phase II, the mean tensile strengths did not decrease. 4. In Group 3. of Ortho-One, Rely-a-Bond, Ortho-Two, and Phase II, the mean tensile strengths decreased about 60.8%, 56.1%, 60.2%, and 46.0%, respectively with statistical significances. (p<0.01) 5. In Group 4. of Ortho-One and Rely-a-Bond, the mean tensile strengths did not decrease. 6. In Group 4. of Ortho-Two and Phase II, the mean tensile strengths were decreased about 20.95% and 22.28%, respectively with statistical significances. (p<0.01) There were formations of a hump shaped mass from bonding resin under blood contamination which disturbed direct bonding procedure. According to Reynolds, the proper bond strength for clinical manipulation should be at least 45N or about 4.5Kg.F. According to these results, it can be concluded that Ortho-One could be used during surgical exposure of unerupted teeth. In any case, blood contamination of the etched surface should be avoided, but the blood contamination of primed surface of Ortho-One may not decrease bond strength. Just 'blowing-out' is enough to remove blood from primed surface of Ortho-One. You can verify the clean surface of the primer of Ortho-One after blowing out the blood contamination.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.62-72
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• 2007

The purpose of present study was to determine whether different kinds of curing lights can alter microtensile bond strength(MTBS) of class I cavity pulpal and axial wall specimens in primary molar. Thirty clean mandibular 2nd primary molar's occlusal enamel were removed and class I cavity, size of $2{\times}4{\times}2mm$ was prepared. Dentin bonding agent was applied according to manufacturer's manual. Each group was cured with Halogen Curing Unit, Plasma Curing Unit and LED Curing Unit. Composite resin was bulk filled and photo cured with same curing unit. MTBS specimens which size is $0.7{\times}0.7{\times}4mm$ were prepared with low speed saw. Specimens were coded by their curing lights and wall positions (Halogen - Axial wall group, Halogen - Pulpal wall group, Plasma - Axial wall group, Plasma - Pulpal wall group, LED - Axial wall group, LED - Pulpal walt group). MTBS were tested at 1 mm/min cross Head speed by Universal Testing Machine. Fractured surface and bonding surface was observed with SEM. T-test between axial and pulpal specimens in each curing lights, one-way ANOVA among different curing light specimens in each wall positions were done. Weibull distribution analysis was done. The results were as follows : Mean MTBS of pulpal wall specimens were significantly greater than that of axial wall specimens at each curing units(p<.05). There was no significant difference in the MTBS among three curing units at axial wall and pulpal wall. In Weibull distribution, pulpal wall specimens were more homogeneous than axial wall specimens.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.882-888
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• 2005

Procedure for analysis of methylmercury in fish was developed, involving addition of HCl, extraction with toluene, and clean-up using L-cystein solution. Obtained extract is analyzed by gas chromatography with electron capture detector using Ulbon HR-Thermon-Hg column. Detection limit and recovery of the method were 0.005mg/kg (expressed as Hg), 98-107 (103%), respectively. Total mercury and methylmercury concentrations in 175 commercial fish samples ranged from [mean-max (mean), unit: mg/kg]: 0.014-1.200 (0.270) and 0.006-0.901 (0.168) in tuna-fish, 0.020-0.934 (0.323) and 0.012-0.553 (0.149) in martin-fish, 0.082-0.782 (0.391) and 0.040-0.436(0.201) in shark, 0,023-0.031 (0.026) and 0,013-0.018 (0.015) in salmon, 0.098-0.193 (0.133) and 0.031-0.015(0.090) in tilefish, and 0,031-0.214 (0.089) and 0.016-0.093 (0.042) in canned tuna respectively. No sample of analyzed fish exceeded 1.0mg/kg wet wt., limit for methylmercury established by Codex. In all species examined, estimated weekly intake was lower than Provisional Tolerable Weekly Intake recommended by the JECFA (the Joint FAO/WHO Expert Committee on Food Additives).

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.2
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• pp.1-9
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• 2011

This study concerns the Baekje Traditional Garden, one of the open spaces in the Lotte Resort in the Baekje Historical Reappearance Complex, which is part of the comprehensive plan for specific areas in the Baekje cultural area. The Baekje Traditional Garden has historic value, and its excellent garden style influenced the ancient Japanese gardens. This study dealt with three issues: (1) The context in which Lotte Buyeo Resort accepted the Baekje Traditional Garden, particularly the background and process of such; (2) The original form of the Baekje Traditional Garden; and (3) How the Baekje Traditional Garden should be represented in the open space of the resort. Representation is accomplished in two ways: using the structure of the original garden and in the borrowing of elements. For representation using the structure of the original garden, Imrugak was used as the main entrance space, and Wolsunjung was represented from the Ganbuklee remains. In the rear garden are wave watercourses and other garden facilities of the Wanggungri site in Iksan. Borrowing of elements, on the other hand, was accomplished in the plant plan and detailed development. In addition, mountaintops (three mountains and five mountain summits), a clean stream between mountains, and a pine forest are visualized in the garden. This is the representative landscape of the Taoist hermit world that appeared in the Baekje Gilt Bronze Incense Burner and Landscape pattern. The significance of this study is twofold. First, the Baekje Traditional Garden is a fresh trail because there has been no previous research concerning it. Second, while past research concerning traditional spaces focused on the results of representation, this study focused on the process of representation. This means that this research work tried to extend the study concerning the representation of traditional spaces from the conceptual to the practical approach. This study, however, also has its limitations. The authenticity of the representation suggested in this study may be questioned later because efforts have been made to preserve the original Baekje Traditional Garden. In addition, this study should seek a balance between authenticity on one hand and amusement and diversity of experience on the other, because the site is a resort.

• Particle and aerosol research
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• v.11 no.3
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• pp.63-75
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• 2015

Atmospheric environment in Korea is influenced by outside, especially China. The concentrations of air pollutants in China have showed decreasing trends since 2000. However, these concentration levels in China are still higher than other developed countries. The Chinese Government has tried several measures to control the air pollution. In this study, the details of the amendments and smog reduction strategies in China, especially for Beijing are reviewed and the strategies for Korean side to promote cooperation in Northeast Asia are suggested and discussed. The Chinese State Council amended the Environmental Protection Provisions and Clean Air Act and announced The Action Plan for Air Pollution Control (2013-2017), focusing on three key regions, Beijing-Tianjin-Hebei area (Jing-Jin-Ji), Yangtze River Delta (YRD) and Pearl River Delta (PRD). These policy actions and plan are mainly for the reducing coal usage and emissions from vehicles. It is suggested that, Korea should actively promote multi-national cooperation in the region to take an initiative role in environmental areas.

• Korean Journal of Plant Resources
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• v.25 no.5
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• pp.624-632
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• 2012

As there have been lately many worldwide resource challenges such as potential exhaustion of fossil fuels, sudden rise of oil price and ever-rising grain pricing due to global food crisis, there have been more interests focused on recycling vegetable oils and fats into clean natural fuel and producing new resources based on waste cooking oil as a part of reusing waste resources. An Experiment was performed by using ratio of 50:50, 75:25 (w/w) mixture of based rapeseed oil, camellia oil, and olive oil. 50:50, 25:75 (w/w) mixture of based palm oil. The result was that the oleic acid ($C_{18:1}$) got the lowest percentage of 42.8%, when we combined the mixture of rapeseed oil and soybean oil. While the highest percentage of 72.1% was when the mixture of camellia oil and rapeseed oil were combined at 50:50 ratio. In 75:25 (w/w) case, mixture of rapeseed oil and soybean oil got the lowest. The highest ratio was the mixture of camellia oil and olive oil. Based on the component of palm oil, the total saturated fatty acid was decreased. It is expected that stabilizing oxidation through controlling of fatty acid after mixture and that liquidity at a low temperature. The acid value indicated that stabilizing oxidation got a range of highest to lowest. Camellia oil ranked as the highest, followed by olive oil, and the oil seeds as the lowest in rank. Controlling iodine value through mixture and improvement of stabilizing oxidation will provide a good quality. The quality of color has no significant change about mixture in ratio and maintenance. The reduction of the cost of refining process is expected by controling of mixture ratio at biodiesel production in the future.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.28 no.3
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• pp.122-130
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• 2010

The Study takes the rivers in Zhouzhuang - traditional Chinese Kangnam watery landscape as the object. The purpose of this study is to grasp the relationships between visual characteristics and the preference. The following is the research process: Firstly, the theoretical study of Zhouzhuang, the traditional Kangnam region in China, is conducted, the watery landscape is taken pictures, and 22 photos are selected. Secondly, in order to grasp the visual preference and landscape characteristics of the watery landscape in Zhouzhuang, 22 pictures and 25 pairs of adjectives are adopted for the questionnaire survey. Thirdly, in order to have a better understanding on the physical properties and effects of physical quantity on the preference, the occupation ratios of buildings and sculptures, natural elements, footpaths, bank revetments and other landscape elements are calculated, and the mean analysis, dispersion analysis and regression analysis are conducted. In order to grasp the landscape characteristics and preference factors, 25 pairs of adjectives are used to conduct the factor analysis. In order to grasp the effects of characteristics of visual factors on the preference, the dispersion analysis and regression analysis are carried out. The results are as follows: From the results of the landscape preference analysis, in the No.22 photo with the top preference, 11 pairs of adjectives, namely, "harmonious-disharmonious", "beautiful-ugly", "rural-urban", "soft-rough", "stable-instable", "romantic-realistic", "cheerful-gloomy", "brilliant-simple", "natural-artificial", "familiar-strange", and "clean-dirty" have positive effects on watery landscape. It can be viewed as the relatively important factor in the visual preference. In terms of the results of visual physical quantity analysis of traditional Chinese Kangnam watery landscape, the landscape with high occupation ratio of buildings and sculptures has positive effects on visual preference. The results of analysis of visual physical quantity and preference show that the preference degree increases as the occupation ratio of footpath area increases. The analysis results of visual characteristics of traditional Chinese Kangnam watery landscape identify four factors, namely psychological factor, cultural factor, condition factor and physical factor. It can be concluded from the results of analysis of the relationships between visual preference and visual characteristics that the return coefficient B of the psychological factor is +0.936. It can significantly affect the watery landscape, so it can be identified as the most important factor among the visual preference factors of Chinese Kangnam watery landscape.