• International Journal of Oral Biology
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• v.36 no.3
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• pp.123-128
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• 2011

The notion that dental amalgam is a potential source of mercury exposure remains a controversial issue. However, there are few epidemiological analyses that have addressed whether this occurs in children. We aimed in our current study to identify the relationship between dental amalgam filling surfaces and the blood mercury levels in a cohort of 711 South Korean children aged between 8-9 years. Oral examinations were conducted to detect the number of amalgam filling surfaces on the teeth of these individuals. Blood samples were also taken from these children to assess the levels of mercury accumulation in the body. The amalgam filling surfaces were classified into four groups based on their number: 0 (n = 368), 1-5 (n = 219), 6-10 (n = 89), and 11+ (n = 35). The blood mercury levels in the children with more than 10 amalgam surfaces was 0.47 ${\mu}g$/L higher on average than those with no amalgam surfaces after adjusting for the frequency of fish or seafood consumption, age, and gender (P < 0.05). We found from our data that a higher number of dental amalgam fillings correlated with a higher blood mercury level in Korean children. Further studies are needed to investigate whether these elevated mercury levels exert neurotoxic or nephrotoxic effects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.140-146
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• 2000

Even though coix (Coix lachryma-jobi L. var. ma-yuen) has many physiological effects, since it has been known to cause sterility, farmers avoid using coix bran as a forage for their livestock. Therefore, as the consumption of coix increases, coix bran, which is a by product of pounding process, becomes a serious issue of environmental problem. Present study examined the physiological effects of coix bran in normal and diabetic rats for its possible use as a functional material. The effects of coix bran supplementation on plasma and hepatic lipid profile were evaluated in rats fed one of the following diet for 12 weeks : chow diet ; chow-bran diet (chow diet＋25% coix bran), high fat diet and high fat-bran diet (high fat diet＋25% coix bran). Additionally, glucose challenge and lipid metabolism in streptozotocin-diabetic rats were also examined. In normal rats, consumption of coix bran remarkably reduced body weight gain in chow or high fat diet fed rats. Additionally, consumption of coix branreduced blood TG, TC and atherogenic index (26%, 24% and 72%, respectively) in chow diet fed rats. Liver TG and cholesterol concentrations were reduced (43% and 49%, respectively) in high fat fed rats by coix bran supplementation. In diabetic rats, fasting blood glucose level was reduced about 25% by coix bran consumption. Also, glucose challenge pattern was improved and resembled normal pattern : it reaches to peak 15~30 minutes after glucose administration and get back to fasting blood glucose level after 90 minutes. Plasma concentrations of TG were elevated in diabetic rats and were reduced to normal level by coix bran supplementation. Liver TG and cholesterol concentrations were also elevated in diabetic rats and reduced to normal level by consumption of coix bran. These results suggest that coix bran may have beneficial effects on blood lipid and glucose level in normal and diabetic rats.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.99-100
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• 2015

Digital image blur occurs due to various environmental conditions at the time of shooting. Blur produces the low-frequency component in the image. This problem worsens the quality of the digital image. To address this issue, contrast improvement methods has been widely studied. 2D filter to enhance the edges is a simple structure with a fast processing speed. However, the sensitivity of the human visual system is different depending on the surrounding brightness locally. Thus, in this paper, we proposed feature-based contrast enhancement method for the digital image using 2D filter to enhance the edges and JND(Just Noticeable Difference) according to the surrounding brightness. We confirmed the result image of proposed method and identified that the contrast is improved.

• Journal of the Korean Institute of Gas
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• v.21 no.6
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• pp.70-80
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• 2017

According with annual report by the OECD (Organization for Economic Co-operation and Development), South Korea is at the top of the list of countries with bad air pollution (fine dust particles) and the South Korean government announced the cause to be due to the particle emissions of large and old diesel vehicles. To solve this issue, the government (jointly with related ministries), promoted the "Special Measures for Comprehensive Fine Dust Management Program" as a way to improve environmental pollution by reducing the overall output of fine dust particles emitted by public vehicles. The measure implemented a gas subsidy system to convert eco-friendly vehicles of city and chartered buses throughout the country. In this study, we take a look at the economical evaluation, comparison and analysis of the conversion of diesel vehicles to natural gas (CNG) vehicles. This report represent the basis for the need to expand the funds of the subsidy program and reviews the feasibility of the policy by taking into consideration the social and economical benefits and the effect in the environment when converting diesel fuel to natural gas vehicles through the type-specific fuel conversion scenarios.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.356-360
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• 2014

The environmental pollution caused by green-house gases such as $SF_2$ has been becoming the main issue of industrial society. As a part of these efforts, 180 countries signed the Kyoto Protocol in 1997 to cut back on their green-house gas emissions [1]. Therefore, a study on the dielectric characteristics of the $GN_2$ is important for designing a eco-friendly high voltage apparatuses. In this paper, to develop an electrically reliable, stable, and eco-friendly high voltage apparatus, the breakdown voltage and partial discharge inception voltage characteristics in $GN_2$ considering utilization factors are studied for the establishment of insulation design criteria of an high voltage apparatus. Dielectric experiments are performed by using several kinds of sphere-plane electrode systems made of stainless steel. Also, the dielectric characteristics of the $GN_2$ are analyzed by using a Finite Elements Method (FEM) according to various field utilization factors. The results are expected to be applicable to designing the high voltage apparatuses using $GN_2$ as an insulation gas.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.220-224
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• 2017

In this study, we investigated a new recycling method of phenol resin, which is widely used to make electric insulation boards and adhesives, into carbon particles by using supercritical fluids. Because phenol resin is insoluble and infusible, most of the phenol resin wastes are buried in the ground or incinerated, which leads to environmental pollution. Therefore, development of a new method to recycle phenol resin waste is an urgent issue. In this study, phenol resin waste was treated with four sub/supercritical solvents: ethanol, acetone, water, and methanol. For all the sub/supercritical solvents, the phenol resin wastes were broken down into carbon nano particles at much lower temperatures than that required in the existing carbon particle manufacturing processes. We investigated the difference of morphologies and physical properties of recycled carbon particles according to the use of various solvents. As a result, carbon nano particles with the same amorphous structure were obtained from phenol resin waste with the usage of various sub/supercritical solvents at much lower temperature.

• KIEAE Journal
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• v.9 no.5
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• pp.47-52
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• 2009

Currently, the environmental issue is of great urgency and sensitivity to the future of our planet. Global warming caused by increased CO2 concentration has an alarming impact on the earth's fragile environment. Droughts throughout the world are causing crop failures. Wildfires now burn with far greater rage. Melting ice caps and glaciers are causing floods. Sea levels are rising. Warm unseasonable winters are threatening our fragile eco-systems. Global warming is no longer a theory; it is an obvious fact we are confronted with every day, and the only way we can prevent it is to take action now. The need to reduce CO2 emissions and try to become carbon neutral is of national importance and leadership. We have become so reliant on fossil fuels that nearly everything we do generates CO2 emissions; from our modern farming practices to transport, to the electricity used to turn on a light, boil water in a kettle or cook our meals. A reduction of 50% of CO2 emissions can easily be achieved by decreasing the energy amount used. We tracked the carbon footprint throughout the electricity and heating energy use in homes and confirmed the amount of carbon emissions according to its consumptions. In order to reduce the carbon generation from housing constructions, such as Passive House concept of buildings or low energy buildings, we must adjust its applications best fit to our conditions. And technical elements should be applied to improve our conditions, and the methodology should be actively sought. Most of all, each individual's recongnition who uses these elements is more important than any other solutions.

• Resources Recycling
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• v.24 no.4
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• pp.61-66
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• 2015

Cyanidation has been used worldwide to recover gold from primary ore or concentrate. The use of cyanide is however becoming an emerging issue because of the toxic residue and wastewater made from the process. The cyanide-containing wastewater should be treated properly, obeying the environmental standard and regulations. In the present article, the domestic and international uses, regulations, and treatment technologies of cyanide in gold mining were investigated as a feasibility study to develop a cyanide treatment process as well as the cyanidation process. A biological cyanide treatment process to develop a zeroemission gold recovery and wastewater treatment process was also briefly introduced.

• Clean Technology
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• v.18 no.1
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• pp.22-30
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• 2012

Separation of $SO_2$ from the flue gases of fossil fuel power plants are important issue because of its strong environmental impact. Industrially, $SO_2$ is being removed with a slurry of limestone, lime or aqueous caustic soda. However, these scrubbing processes possess several drawbacks such as the generation of huge amount of wastewater and the production of metal salts. Recently, ionic liquids have gained increasing interest as an absorbent for acid gas, $CO_2$ and $SO_2$. In this review, we have introduced the recent progress of ionic liquids as a $SO_2$ absorbent.

• Anxiety and mood
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• v.13 no.1
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• pp.25-31
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• 2017

Objective : The purpose of this study was to evaluate the factors associated with the experience of bullying victimization in school among elementary school students in the Jeju area. Methods : A total of 662 students were recruited from elementary schools for a school-based cross-sectional survey (age range : 11-12 years) in the Jeju area. This study used a self-reported questionnaire concerning the experience of being victimized by bullying, the Korean form of the Children's Depression Inventory (CDI) to assess depressive symptoms, and questions on sociodemographic characteristics, including school- and family-related factors. Results : The prevalence of bullying victimization in school among elementary school students was 10.0% (n=66). The factors associated with bullying victimization were lower socioeconomic status, lower than average academic achievement, more depressive symptoms, and family problems. Conclusion : This study not only indicates that bullying at school is a significant public health issue among elementary school students, but also confirms that children with family problems commonly exhibit bullying behaviors, which highlights the importance of considering family-related environmental factors when managing bullying victimization.