• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.4
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• pp.115-124
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• 2007

The material compressions in the vertical composting reactor affect to the biodegradation rates of the organic wastes. This study investigated the variations of physical properties of the composting materials according to the height of reactor due to affect to the settlement in the vertical composting reactor. The variations of decreased temperature after peak temperature showed the different patterns depending on the reactor heights. The variation width of re-increased temperature after peak temperature was reduced as the mixing operations were increased, and increased as the height of reactor elevated. The moisture content and the variation width of the moisture content were increased higher as the height of the reactor became higher. The variations of the bulk density at each height of vertical reactor showed the same tendency comparing with those of the moisture content. The relationship between bulk density and moisture content had shown the quadratic equation (r2=0.94). The dry solid contents at each reactor height were decreased as the height of reactor were increased. The results of the variation of the physical properties during the composting process were caused by the downward compression of the material into the reactor. Settlement rate in the vertical composting reactor was estimated about 2.184cm/day. To increase the biodegradation efficiency in the vertical reactor, the conditions of air path in the composting material matrix have to be investigated afterwards.

• Journal of dental hygiene science
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• v.13 no.1
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• pp.97-104
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• 2013

This study investigated the safety management behavior of dental professionals to minimize exposure to harmful elements of amalgam and resin. As for the use of amalgam and resin, 85.8% of them used amalgam. 100% of used composite resin 100%. 97.8% used acryl resin, and 95.7% used tray resin. 95.2% and 36.5% of them were aware of the harm of amalgam and resin respectively. When using resin, their safety management behavior score was 1.99 on average, and the lowest score was 2.50 on average for 'ventilate the indoor air when handling resin'. Their average score of the safety management behavior was 1.83 when using amalgam. The lowest score was 2.89 on average for 'use the rubber dam for patients when handling amalgam'. As a result of the safety management behavior based on general characteristics, all characteristics were significant with regard to amalgam, and my position at work and work experience were significant with regard to resin (p<0.05). The correlation between the safety management behavior and general characteristics was analyzed when dental amalgam and resin are used. Amalgam was statistically correlated with academic background (p<0.05) and position at work (p<0.05), whereas resin was statistically significantly correlated with age (p<0.05) and position at work (p<0.05). Accordingly, education about the harm of dental materials must be continuously provided for dental professionals when they handle dental materials so that safety management behavior will be conducted correctly, and active efforts to protect the health of dental professionals from harmful chemicals must be made.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.329-336
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• 2006

Iron manufacturing process involves production of various by-product including slag, sludge, sintering and EAF(Electric Arc furnace dust). Some of the by-products such as EAF and sintering dust are disposed of as waste due to their high heavy metal contents. It has been notice for many years that the EAF dust also contain about 65% of Fe(0) and Fe(II) and then the possible utilization of the iron. One possibility is to apply the EAF as a lining material in conjunction with clay or HDPE liners, in waste landfill. The probable reaction between the leachate containing toxic elements such as TCE, PCE dioxine and $Cr^{6+}$ is reduction of the toxic materials in corresponding to the oxidation of the reduced iron and therefore diminishing the toxicity of the leachate. It is, however, prerequisite to evaluate the leaching characteristics of the EAF dust before application. Amelioration of the leachate would be archived only when the level of toxic elements in the treated leachate is less than that of in the untreated leachate. Several leaching techniques were selected to cover different conditions and variable environments including time, pH and contact method. The testing methods include availability test, pH-stat test and continuous column test. Cr and Zn are potentially leachable elements among the trace metals. The pH of the EAF dust is highly alkaline, recording around 12 and Zn is unlikely to be leached under the condition. On the contrary Cr is more leachable under alkaline environment. However, the released Cr should be reduced to $Cr^{3+}$ and then removed as $Cr(OH)_3$. Removal of the Cr is observed in the column test and further study on the specific reaction of Cr and EAF dust is underway.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.4
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• pp.227-235
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• 2005

This study aimed at suggesting management policy directions for the uninhabited islands of Korea which are national land resources with economic potential for tourism and development and strategic value for boundary delineation of territorial waters and exclusive economic zone as well as their unique ecological status. Review of existing management arrangements related to the uninhabited islands revealed six management issues to be addressed: insufficient data and their low reliability, lack of management policy directions, increase in ecosystem deterioration and perturbation by human activities, lack of policy measures for meeting utilization and development demands, weak management base with insufficient personnel and budget, and legal measures not taking Into account their unique ecological and socioeconomic characteristics. The management policy directions to improve the management of the uninhabited islands of Korea include management directions and strategies, and suggestions for legal improvement. Considering the unique ecological value of the uninhabited islands, management directions suggested are anti-degradation in which current and future demands for their utilization and development do not degrade the ecological potential of the uninhabited islands and integration in which land and sea areas are managed as an integrated management unit. Four strategies proposed to follow the management directions are enhancement of the knowledge base through a comprehensive survey, development and legislation of guidelines for the rational management of utilization and development demands, establishment of the comprehensive island debris collection and disposal system, and enhancement of management capacity. Legal improvement for the effective implementation of the management policy directions should include comprehensive uninhabited islands survey, legal utilization restraints and management guidelines based on classification of the islands, management boundary, and improvement of regulations on designated islands.

• Journal of Life Science
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• v.31 no.7
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• pp.617-625
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• 2021

To enhance the applications of apple pomace, which is a by-product of apple, this study analyzed the nutritional components, ursolic acid content, and antioxidant activity of different solvent (distilled water, fermented alcohol, and methanol) extracts. The samples included hot air-dried and freeze-dried apple pomace. The moisture, protein, fat, ash, and total dietary fiber contents of hot air-dried apple pomace were 3.2%, 3.9%, 2.4%, 2.0%, and 28.5%, respectively, and those of freeze-dried apple pomace were 8.2%, 3.4%, 2.4%, 1.8%, and 33.0%, respectively. Ursolic acid was not detected in the distilled water extract of either sample. However, in hot air-dried apple pomace, the methanol extract was 1,753.32 ㎍/ml, and the fermented alcohol extract was 1,532.94 ㎍/ml. In freeze-dried apple pomace, the methanol extract was 1,407.04 ㎍/ml, and the fermented alcohol extract was 1,221.81 ㎍/ml. The total polyphenol and flavonoid contents were 306.7 ㎍/ml and 950.1 ㎍/ml, respectively in methanol extracts of hot air-dried apple pomace and 277.6 ㎍/ml and 925.0 ㎍/ml, respectively in methanol extracts of freeze-dried apple pomace. 2, 2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities of hot air-dried apple pomace were 73.3% in methanol extract and 59.4% in fermented alcohol extract, and those of freeze-dried apple pomace were 76.1% in methanol extract and 66.0% in fermented alcohol extract. Both samples had the lowest antioxidant activity in distilled water extracts. Similar to DPPH radical scavenging activity, both samples showed increasing 2,2'-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS) radical scavenging activity in the order of methanol, fermented alcohol, and distilled water. All samples had stronger reducing power than ascorbic acid (311.5 ㎍/ ml) as a positive control.

• Resources Recycling
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• v.31 no.5
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• pp.67-76
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• 2022

The furniture industry has a high possibility to create value-added and a high potential to create new occupations due to the characteristics of the industry, which mainly consists of small and medium-sized enterprises (SMEs). However, the used furniture, which has sufficient reuse value, is also crushed and used as solid refuse fuel (SRF) recently. Besides, the number of waste treatment companies continues to decrease, and it occurs congestion of wood waste. As a way to solve the issue, a business model development of remanufacturing used furniture can be suggested as an alternative due to its high circular economic efficiency. Remanufacturing business including furniture industry creates positive effects in various aspects such as economic, environmental and job creation. In other words, remanufacturing is an effective recycling way to reduce input resources and energy in the production process. The results of economic analysis show that the expected annual revenue from the single worker furniture remanufacturing site was 104 million won which is 3.11 times more than the average income of a single-worker household in Korea and its B/C ratio was estimated about 30 which means high business feasibility. Revenue through furniture remanufacturing also showed 320 times higher than that of SRF production from the perspective of weight. In addition, it is shown that the GHGs reduction from the furniture remanufacturing is 2.2 ton CO₂-eq. per year, which is similar to the amount of GHGs absorption effect of 937 pine trees or 622 Korean oak trees annually. Thus the results of this study demonstrate that it is important to adopt an appropriate recycling method considering the economic and environmental effects at the end-of-life stage.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.3
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• pp.153-161
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• 2023

The worldwide effects of COVID-19 have led to a surge in online shopping and contactless services. The consumption pattern has caused the issues such as the environmental pollution together with the increase of plastic waste. Reducing the reliance on the petroleum based plastic use for the package and replacing it with environmentally friendly material are the simple ways in order to solve those problems. Paper is an eco-friendly product with high recyclability as the food packaging materials but has still poor barrier properties. A barrier coating on surface of the paper can be achieved with the proper packaging materials featuring water, gas and grease barrier. Polyethylene (PE) or polypropylene (PP) coatings which are generally laminated or coated to paper are widely used in food packaging applications to protect products from moisture and provide water or grease resistance. However, recycling of packaging containing PE or PP matrix is limited and costly because those films are difficult to degrade in the environment. This study investigated the recyclability of modified acrylic emulsion coating papers compared to PE and PP polymer matrixes as well as their mechanical and gas barrier properties. The results showed that PE or modified acrylic emulsion coated papers had better mechanical properties compared to the uncoated paper as a control. PE or PP coating papers showed strong oil resistance property, achieving a kit rating of 12. Those papers also had a significantly higher percentage of screen reject during the recycling process than modified acrylic coated paper which had a screen rejection rate of 6.25%. In addition an uncoated paper had similar value of a screen rejection rate. It may suggest that modified acrylic emulsion coating paper can be more easily recycled than PE or PP coating papers. The overall results of the study found that modified acrylic emulsion coating paper would be a viable alternative to suggest a possible solution to an environmental problem as well as enhancing the weak mechanical and poor gas barrier properties of the paper against moisture.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.36-43
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• 2024

Fishing net waste (FNW) constitutes over half of all marine plastic waste and is a major contributor to the degradation of marine ecosystems. While current treatment options for FNW include incineration, landfilling, and mechanical recycling, these methods often result in low-value products and pollutant emissions. Importantly, FNWs, comprised of plastic polymers, can be converted into valuable resources like syngas and pyrolysis oil through pyrolysis. Thus, this study presents a process for generating high-purity hydrogen (H₂) by catalytically pyrolyzing FNW in a CO₂ environment. The proposed process comprises of three stages: First, the pretreated FNW undergoes Ni/SiO₂ catalytic pyrolysis under CO₂ conditions to produce syngas and pyrolysis oil. Second, the produced pyrolysis oil is incinerated and repurposed as an energy source for the pyrolysis reaction. Lastly, the syngas is transformed into high-purity H₂ via the Water-Gas-Shift (WGS) reaction and Pressure Swing Adsorption (PSA). This study compares the results of the proposed process with those of traditional pyrolysis conducted under N₂ conditions. Simulation results show that pyrolyzing 500 kg/h of FNW produced 2.933 kmol/h of high-purity H₂ under N₂ conditions and 3.605 kmol/h of high-purity H₂ under CO₂ conditions. Furthermore, pyrolysis under CO₂ conditions improved CO production, increasing H₂ output. Additionally, the CO₂ emissions were reduced by 89.8% compared to N₂ conditions due to the capture and utilization of CO₂ released during the process. Therefore, the proposed process under CO₂ conditions can efficiently recycle FNW and generate eco-friendly hydrogen product.

• Korean Journal of Organic Agriculture
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• v.13 no.3
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• pp.315-332
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• 2005

This study was conducted to assess the nutritional value and the safety of the fermented food wastes (FFW) made by adding lactobacillus spp. and bacillus spp. at the ratio of 3:7, respectively to food wastes collected everywhere, and also to determine effects on the performances, carcass characteristics and economical profitability when FFW was fed to pigs. For swine trial, FFW was formulate to pellet by utilizing different feed ingredients, and its formulated FFW pellet was used in this feeding trial. Treatments were consisted of different ratios (T1: $100+0\%$, T2: $75+25\%$, T3: $50+50\%$, T4: $25+75\%$, T5: $0+100\%$) of FFW pellet to commercial diet. A total of 20 male pigs were allotted to treatments of five groups of four pigs per pen. Experimental period lasted for 4 months. The nutritional composition of FFW was 56.7, 19.5 and $19.5\%$ for moisture, crude protein and ether extract, respectively. Salt content was $0.39\%$. Noxious microorganisms such as salmonella and E. coli were not detected in FFW, and contents of heavy metal and aflatoxin B1 were lower than the standard. Nutritional values of FFW pellet satisfied over $100\%$ of requirements presented in official Korean feeding standard for swine. Feeding trial for pigs showed that feed intakes were significantly (P<0.05) decreased with increasing levels of FFW pellet. T2 treatment was ideal ratio under the consideration of economical value of feeds and body weight gain of pigs. For carcass characteristics, dressing rate ($\%$) was highest in T3, and carcass grades for T2, T3 and T4 treatments were estimated as 'A'. Feed cost for FFW per kg was ${\won}167.95$, which implies $52\%$ of commercial feed cost (${\won}350/kg$). Thus, this result implied the decreased feed cost in the swine farm. Conclusively, the utilization of food wastes as feed source may lead to the reduced environmental pollution and the practice of organic livestock farming. However, our results showed that excessive amount of fermented food wastes supplementation to pigs might give rise to their reduced palatability and delayed growth.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.2
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• pp.149-160
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• 2013

The objective of present study was to simultaneously isolate of isoflavone and soyasaponin compounds from the germ of soybean seeds. Soy germ flours were defatted with hexane for 48h at room temperature, and methanolic extracts were prepared using reflux apparatus at $90^{\circ}C$ for 6h, two times. After extraction, extracts were separated with preparative RP-$C_{18}$ packing column ($125{\AA}$, $55-105{\mu}m$, $40{\times}150mm$), and collected 52 fractions were identified with TLC plate (Kieselgel 60 F-254) and HPLC, respectively. Among the identified isoflavone and soyasaponin fractions, isoflavone fractions were re-separated using a recycling HPLC with gel permeation column (Jaigel-W252, $20{\times}500mm$). Final fractions were air-dried, and the purified compounds of two isoflavones (ISF-1-1, ISF-1-2) and four soyasaponins (SAP-1, SAP-2, SAP-3, SAP-4) were obtained. Two isoflavone compounds (ISF-1-1, ISF-1-2) were acid-hydrolyzed for the identification of their aglycones, and confirmed by comparing with 12 types of isoflavone isomers. While the four kinds of soyasaponins were identified by using a micro Q-TOF mass spectrometer in the ESI positive mode with capillary voltage of 4.5kV, and dry temperature of $200^{\circ}C$. Base on the obtained results, it was conclude that ISF-1-1 is the mixture isomers of daidzin (43.4%), glycitin (47.0%), and genistin (9.6%), but ISF-1-2 is the single compound of genistin (99.8% <). On the other hand, soyasaponin SAP-1 is the mixture compounds of soyasaponin A-group (Aa, Ab, Ac, Ae, Af); SAP-2 is soyasaponin B-group (Ba, Bb, Bc) and E-group (Bd, Be); SAP-3 is soyasaponin B-group (Ba, Bb, Bc), E-group (Bd, Be), and DDMP-group (${\beta}g$); SAP-4 is soyasaponin B-group (Ba, Bb, Bc), E-group (Bd, Be), and DDMP-group (${\beta}g$, ${\beta}a$), respectively.