• Resources Recycling
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• v.10 no.3
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• pp.51-59
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• 2001

Impurities removal from waste carbon black was carried out to produce high-grade carbon black. A large amount of hydrophilic carbon black is produced as a byproduct of the hydrogen production process by flame decomposition of water. Due to its impurities content such as sulphur, iron, ash, etc., it can only be used as low-grade carbon or burnt out. High-grade hydrophilic carbon black is 3~5 times more expensive than oil-based carbon black because of high production cost associated with process complexly and pollutant treatment. Hydrophilic carbon is normally used for conductive materials for batteries, pigment for plastics, electric wire covering, additives for rubber, etc. In these applications, impurity content must be blow 1 fe. In this study, magnetic separation, froth flotation and ultrasonic treatment were employed to remove impurities from the low-grade hydrophilic carbon black. Results showed that the ash, iron and sulphur content of product decreased to less than 0.01 wt.%, 0.01 wt.% and 0.3 wt % respectively and the surface area of product was about 930 $m^2$/g for conductive materials.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.291-299
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• 2018

The purpose of this study was to review the government's policy on the enhancement of sports facilities for community residents regarding the lack of knowledge surrounding the infrastructure of sports facilities. The government has invested approximately 2.4 trillion won to establish 220 community sports centers, 385 billion won for 194 multi-purpose indoor centers, and 1.3 trillion won for rebuilding 1,870 school outdoor fields. On the other hand, there are problems with the link between the crumb rubber infill on sports fields and cancer, a lack of availability of indoor sports centers, and an increased federal budget deficit. It is the responsibility of government to plan and construct outdoor fields that are large enough to accommodate all people and allow them to play activities. In addition, the guidelines should ensure that the indoor space required for physical activities at each teaching station is large enough to accommodate all students in the class and handle two classes. The government should suggest the federal government guidelines based on a good understanding of the concept of infrastructure in sports facilities. The government also should make efforts to reduce the regulatory powers and provide the community with an autonomous right to plan and construct sports facilities.

• Journal of Digital Convergence
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• v.16 no.4
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• pp.195-203
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• 2018

This study was conducted to investigate the types and methods of dental impression materials used in dental clinics in south Korea, the questionnaire was surveyed by a self-administered method for one dentist in a one dental clinic, the collected data were statistically analyzed using SPSS 20. The most frequently used addition silicone impression materials were used in most dental treatment. It was confirmed that the method of taking impression materials having different flow properties(light body and heavy body) was most preferred at one time, also, the implant impression taking method was the most preferred for two rubber impression materials with different flow properties, both direct and indirect. There were statistically significant differences in age and clinical experience between the methods of impression taking of casting restorations and prosthetic according to general characteristics. These results are expected to be helpful for the development of theoretical and practical work based on the basic data for impression material development and research and the preference of impression materials required for dental professional in clinical practice.

• Elastomers and Composites
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• v.47 no.1
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• pp.2-8
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• 2012

In this study, in order to develop renewable bio-based nanocomposites, multi-functional nanocomposites from soybean resins (AESO, MAESO) and nanoclay were prepared. Photoelectrodes for environmental friendly dye-sensitized solar cell using soybean resin were also prepared. Organo-modified nanoclay was directly dispersed in functionalized soybean resins after mixing with styrene as a comonomer and radical initiator was used to copolymerize the nanocomposites. The observed morphology was a mixture of intercalated/exfoliated structure and the physical properties were improved by adding nanoclay. A nanocomposite using MAESO, which added COOH functional group to the soybean resin, showed better dispersibility than AESO composites. Ultrasonic treatment of the nanocomposites also improved the physical properties. Nanoporous $TiO_2$ photoelectrode was also prepared using soybean resins as a binder, after acid-treatment of $TiO_2$ surface using nitric acid. Dye-sensitized solar cells were prepared after adsorbing dye molecules on it. The $TiO_2$ photoelectrode prepared using soybean binder had high current density because of increased surface area by improved dispersibility. The photoelectrochemical properties and conversion efficiency of the solar cell were significantly improved using the soybean binder.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.8
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• pp.711-719
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• 2016

In this study, we derived an theoretical equation, using a simplified spring-mass model for the rolling stock, to obtain the overriding behavior of a leading vehicle, which is considered as the main factor in train accidents. To verify the derived equation, we created a simple 2D model based on the theoretical model, and a simple 3D model considering the characteristics of the power bogie. We then compared the theoretical results with the simulation results obtained using LS-DYNA. The maximum relative derivations in the vertical displacements at the first end-buffer, which is the most important point in overriding, were 3.5 [%] and 1.7 [%] between the two results. Further, we evaluated collision-induced overriding displacements using the theoretical equation for a rubber draft gear, a hydraulic buffer under various collision conditions. We have suggested a theoretical approach for the realization of overriding collision accidents or the energy absorption design of the front end of trains.

• The Research Journal of the Costume Culture
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• v.9 no.1
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• pp.61-72
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• 2001

Chunghahk-dong is located in a retired spot, Jiri Mountain and has been built up its won religion and culture without any exchange outside world. People in Chunghahk-dong believe in a religion called Genjungyutaosim. Forming a trinity on which mind is Taoism, body is Buddhism, and behavior is confucianism. These are the principle elements to form a village. They made their own unique cultural factor such as longhaired boys and girls, wearing traditional cloths and hat, a monastic life, folk mores and family rituals, and private school system. This shows a great deal of affection on their life style and organization and is closely connected with community and culture. Grasping a culture and behavior on clothing, it has propose to understand Chunghahk-dong properly according to this study. A method of study has a purpose to understand culture and clothing behavior precisely in Chunghahk-dong. I inquire ito clothing behavior with investigation and study of picture script. The results are as followed; People in Chunghahk-dong show unique clothing and hair style behavior based on Genjungyutao. First, men and women wear a white cloth called HanBok(Korean costume) and footwear made of rubber. Only men wear a blue vest. A grown up men wear a long coat when they go out. They are dressed in tractional cloth for a ceremonial occasion. The reason why they put on the HanBok(Korean costume) is a belief on our traditional cloth becomes a standard dress in the future. They believe Korea becomes a standard dress in the future. They believe Korea becomes a standard dress in the future. They believe Korea become a leading country in the world. This clothing behavior is symbol of Genjungyutao and has a role of delivery system for expressing their split. Second, In sign of being a Genjungyutao men, they let their grow hair. Cutting hair is not to be a Genjungyutao men any more. There is few reason that people in Chunghahk-dong let grow their hair : First, because of importance in TanGun's ideology, they believe Korea is a first nation in the world and can't cut their hair which has grown from TanGun (The founding father of the Koran nation) Chosun traditionally. Second, Cutting their hair runs counter to the principle of nature. Third, They value their body for confucianism. They don't want to damage their body because of body from their parents. Boys and girls braid and tie up their hair and adult tie a topknot and a chignon. Wearing a YouGun(A horsehair skullcap) at home and Kat(A Korean top hat) when going out, they express as a Genjungyutao. Hemp cloth and synthetic fibers are main clothes. Also, they wear an improved HanBok(Korean costume) these days on influence outside.

• Journal of Environmental Science International
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• v.27 no.2
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• pp.91-97
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• 2018

This study carried out first a component survey on the domestic waste shipped into a waste disposal facility in B city, and then heavy metal analysis of each component according to the SRF standards. Based on this, this study explored the problems with domestic waste and measures to improve them. The results are as follows. The result of the survey of physical components show that paper accounted for the largest proportion with 20.5 %~59.9 %, metals (including batteries) among incombustibles accounted for 0.0~8.3 %, other inorganic substances, glass and ceramics accounted for 0.0~43.7 % and 0.0 %~19.6 % respectively. However, the proportion of coated viny and plastics, which have high lead and cadmium content, was rather high with 2.9 %~30.9 %. This suggests the possibility that actual concentration of lead and cadmium within SRF is likely to be higher. Among the 15 components contained in the waste brought into the waste disposal facility, 10 components (food waste, textiles, vinyl, plastics, wood, rubber and leather, paper, metals, electronic substrates, and nail polish) were analyzed according to assay samples (approximately 0.1 g and 0.3 g). The result of analysis shows that the amount of Cd and Pb detected in coated vinyl for 0.109 g of assay sample was 98.6 mg/kg and 20.6 mg/kg respectively; 117.0 mg/kg and 29.0 mg/kg respectively for 0.313 g of assay sample. This is high contents exceeding the Cd standard. As for wooden component, the amount of Pb was 480.0 mg/kg for 0.3 g of assay sample. This suggests that there always exists the possibility of exceeding the exposure level of heavy metals (Cd and Pb) in SRF as long as coated wood and vinyl plastics with high contents of Pb and Cd are shipped into the waste disposal facility; and the local government and the residents need to work hard to improve the situation including development of the machine to sort electronic substrates and batteries for separate collection of the waste of coated vinyl and plastics within domestic waste.

• Elastomers and Composites
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• v.46 no.1
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• pp.37-44
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• 2011

Effect of organo nanoclay (Cloisite 30B) on the polyesterification of adipic acid (AA) with diethylene glycol(DEG) was investigated with p-toluene sulfonic acid (p-TSA) (Br${\phi}$nsted acid) and butylchlorotin dihydroxide (Lewis acid) catalyst at 383 and 423 K. The initial [OH]/[COOH] molar ratio was two and the concentration of the catalysts in the reactants was 0.14 mol% based on the total reactants. The kinetics of the polyesterification was interpreted with the conversion data that was calculated from the acid values of the reactant-product mixture. The reaction rate of the polyesterification, which was catalyzed with p-TSA, exhibited the second-order dependency on AA concentration. When Butylchlorotin dihydroxide was used, the reaction rate revealed the first-order dependency on AA concentration. The activation energy of the reactions catalyzed with p-TSA and Butylchlorotin dihydroxide were calculated at 42.2 and 63.8 kJ/mol, respectively. Addition of 5 wt% Cloisite 30B to the reactant significantly diminished the activity of p-TSA, so the reaction rate decreased and the activation energy was calculated at 72.9 kJ/mol. Butylchlorotin dihydroxide catalyst maintained its activity regardless of the addition of Cloisite 30B to the reactant and the activation energy was calculated to 61.8 kJ/mol. Lewis acid catalyst, butylchlorotin dihydroxide, was more effective than Br${\phi}$nsted acid catalyst for the esterification of AA with DEG.

• 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.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.195-201
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• 2022

This study aims to evaluate the feasibility of the disinfection of clinical ultrasound probes using the vapor fumigation method, which can quickly achieve high-level disinfection. Upon the inspection of the microbial contamination level of clinically used ultrasound probes, nine different types of bacteria were detected. The disinfection efficacy of 7.5% and 35% hydrogen peroxide (H₂O₂) was comparatively tested for the detected microbes. The 35% H₂O₂ demonstrated superior efficacy per disinfection duration. No significant change was observed in the rubber component of the ultrasound probes as a result of the 35% H₂O₂ disinfection treatment. The probes were contaminated with the microbes detected in the microbial contamination level inspection and subsequently disinfected using the novel medical disinfector that utilizes the vapor fumigation method. As a result, the disinfection using the novel device achieved 100% eradication of the microbes from the probes.This study demonstrates that the novel vapor fumigation method-based disinfector provides a faster and more powerful means of disinfection than the conventional disinfection methods. Therefore, the novel disinfector has the potential to be used as a convenient ultrasound probe disinfector in clinical settings.