• Journal of Animal Environmental Science
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• v.2 no.2
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• pp.147-154
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• 1996

In an attempt to recycle as feed or fertilizer, broiler litter containing rice hull was manually composted under the control of peak temperature of piles(uncontrolled or controlled below $70^{\circ}C$ or below $60^{\circ}C$) in each of three $1.0\;{\times}\;1.0\;{\times}\;1.2m$ dimensional facilities. Changes of nutritional and microbiological parameters were evaluated throughout the 8 weeks of processing period. The initial content of crude protein(29.6%) decreased to 17.8% after 8 weeks of composting. The rapid nitrogen(N) loss observed in the early phase was attributed mainly to non-protein-N(NPN) loss. The initial content of ash(19.1%) increased to $26{\sim}29%$ after 8 weeks. For toxic heavy metals, Cr, Pb, and Hg contents of final composts were far less than the maximum tolerance levels allowed in food or compost. Bacterial growth was rather depressed until the second week, increased thereafter, and reached to peak($10^{12}cfu$ level) at the 4th week of composting. With composting, actinomycetes were active at the level of $10^7\;to\;10^9$. Fungi were active during the first to third week of composting. In general, control of pile temperature below $70^{\circ}C$ did not remarkably alter the nutritional and microbiological parameters of broiler litter compost, compared to that of pile temperature below $60^{\circ}C$. Further researches on prevention from the rapid loss of NPN in the early phase of composting are required for more effective recycling of broiler litter.

• Environmental Engineering Research
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• v.11 no.1
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• pp.14-27
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• 2006

The proper management of discarded electronic devices (often called electronic-waste) is an emerging issue for solid waste professionals throughout the world because of the large growth of the waste stream, and the content of toxic metals in them, most notably heavy metals such as lead. Notebook computers are becoming one of the major components of discarded computer devices and will continue to increase in the waste stream in the future. While the computers hold great promise for recycling, a substantial amount of this waste is often disposed in municipal solid waste (MSW) landfills. The toxicity characteristic leaching procedure (TCLP) is commonly used to simulate worse case leaching conditions where a potentially hazardous waste is assumed to be disposed along with municipal solid waste in a landfill with actively decomposing materials overlying an aquifer. The objective of this study was to examine leaching potential of lead from discarded notebook computers using the scale-up TCLP, other standard leaching tests such as California waste extraction test (Cal WET), and the synthetic precipitation leaching procedure (SPLP) and actual landfill leachates as leaching solution. The scale-up TCLP is a modified TCLP (where the device was disassembled and leached in or near entirety) to meet the intent of the TCLP. The results showed that the scale-up TCLP resulted in relatively high lead found in the leachate with an average of 23.3 mg/L. The average level was less than those by the standard TCLP and WET (37.0 mg/L and 86.0 mg/L, respectively), but much greater than those by the SPLP and the extractions with the landfill leachates (0.55 mg/L and 1.47 mg/L, respectively). The pH of the leaching solution and the ability of the organic acids in the TCLP and WET to complex with the lead were identified as major factors that controlled the amount of lead leached from notebook computers. Based on the results obtained by a number of leaching tests in this study, notebook computers may present a potential leaching risk to the environment and human health upon land disposal. However, further investigation is still needed to assess the true risk posed by the land disposal of discarded notebook computers.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.215-220
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• 2016

A new immobilization technique of nanoscale $TiO_2$ powder to expanded polystyrene (EPS) balls with temperature-controlled melting method was developed, and the photocatalytic activity of $TiO_2$ powder-embedded EPS balls were evaluated using methylene blue (MB) solution under ultraviolet irradiation (${\lambda}=254nm$). Based on the scanning electron microscope (SEM) images and associated energy-dispersive X-ray spectroscopy (EDX) analysis, the components of the intact EPS balls were mainly carbon and oxygen, whereas those of $TiO_2$-immobilized EPS balls were carbon, oxygen, and titanium, indicating that relatively homogenous patches of $TiO_2$ and glycerin film were coated on the surface of EPS balls. Based on the comparison of degradation efficiencies of MB between intact and $TiO_2$-immobilized EPS balls under UVC illumination, the degradation efficiencies of MB can be significantly improved using $TiO_2$-immobilized EPS balls, and surface reactions in heterogeneous photocatalysis were more dominant than photo-induced radical reactions in aqueous solutions. Thus, $TiO_2$-immobilized EPS balls were found to be an effective photocatalyst for photodegradation of organic compounds in aqueous solutions without further processes (i.e., separation, recycling, and regeneration of $TiO_2$ powder). Further study is in progress to evaluate the feasibility for usage of buoyant $TiO_2$-immobilized EPS to inhibit the excessive growth of algae in rivers and lakes.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.4
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• pp.265-275
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• 2012

Objectives: The aim of this study was to investigate the distribution patterns and exposure concentrations of biological hazards in waste handling industries. Methods: We selected 3 recyclable waste sorting plants(RWS), 2 food recycling plants(FR), 1 landfill area(LA) and 1 waste incineration plant(WI). Total airborne bacteria and fungi were measured with single stage impactor and gelatin filters. Endotoxin and glucan were measured with polycarbonate filters in total and respirable dust. Results: The geometric mean of airborne bacterial concentration was the highest in FR($3,273CFU/m^3$), followed by LA, RWS, and WI as 1,334, 934, and $860CFU/m^3$. The fungal concentrations were 6,031, 5,052, 3,307, and $713CFU/m^3$ in RWS, WI, FR, and LA, respectively. By process, WI pit showed the highest concentrations of bacteria, fungi, and endotoxin, followed by inside of bulldozer in LA. The indoor to outdoor ratios of bacteria, fungi, endotoxin and glucan were 2.3, 4.0, 2.3, and 5.0 in RWS, 29.5, 4.9, 7.6, and 5.0 in FR, 5.3, 8.7, 26.8, and 9.5 in WI, respectively. Conclusions: We found that biological hazards, specifically bacteria in FR, fungi in RWS and endotoxin in WI pit and bulldozer at LA, should be controlled to prevent worker's respiratory diseases.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.3
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• pp.40-46
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• 2015

For some Korean newsprint mill, addition level of aluminum sulfate has been reduced because sulfur from aluminum sulfate has detrimental effect on the efficiency of anaerobic water treatment. At this moment, an unexpected decrease in sizing degree of TMP mixed newspaper was occurred. The phenomena means that hydrophobic substance usually originated from TMP cannot be fixed on the paper. This study focused on effect of alum and PAC on sizing of paper and contamination. Also, substitutability of PAC was discussed as a possible alternatives of aluminum sulfate under anaerobic condition of water treatment. Evaluation of sizing degree and pitch deposit potential were performed at the varied addition level of PAC and aluminum sulfate. Hydrophobic substance mainly derived from TMP could be fixed on the surface of fiber by PAC. Fines retention was not changed by replacing aluminum sulfate with PAC. Additionally, fixing of hydrophobic substance without excessive agglomeration can be enhanced by PAC with low molecular weight. Consequently, sizing degree of newspaper and contamination of recycling process of ONP can be controlled by low molecular weighted PAC.

• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.441-448
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• 2020

In this study, the engineering characteristics of CLSM mixed with GBFS and GF were identified to review the applicability as a replacement material and further evaluate the recharge and field applicability as a joint filler material. This study has resulted in the following findings. First, Using more than 30% of GBFS to replace FA enabled bleeding control through improved fluidity. Moreover, it has been confirmed that effective strength and proper quality can be achieved when it was applied as a refiller and joint filler material with higher early strength than the base material. Second, When using more than 30% of FNS to replace sand, it was found that adding 0.3~0.35 of the AE agent is effective for bleeding control through improved fluidity. Third, When using more than 30% of both GBFS and FNS in combination, it was found that adding 0.3~0.35 of the AE agent is effective for bleeding control through improved fluidity. Also, it was confirmed that proper mixing of 15~60% of GF secured the effective strength and desired quality as a refiller and joint filler material. Fourth, The relationship between the superficial level and internal micro pores of CLSM from the curing process needs to be discussed and reviewed in more detail through further research studies.

• Composites Research
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• v.35 no.4
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• pp.242-247
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• 2022

This study has a different direction from the existing technology of applying recycled carbon fiber obtained by recycling waste CFRP to CFRP again. A study was conducted to utilize recycled carbon fiber as a raw material for manufacturing a carbon/carbon (C/C) composite material comprising carbon as a matrix. First, it was attempted to recycle a commonly used epoxy resin composite material through a thermal decomposition process. By applying the newly proposed oxidation-inert atmosphere conversion technology to the pyrolysis process, the residual carbon rate of 1~2% was improved to 19%. Through this, the possibility of manufacturing C/C composite materials utilizing epoxy resin was confirmed. However, in the case of carbon obtained by the oxidation-inert atmosphere controlled pyrolysis process, the degree of oxygen bonding is high, so further improvement studies are needed. In addition, short-fiber C/C composite material specimens were prepared through the crushing and disintegrating processes after thermal decomposition of waste CFRP, and the optimum process conditions were derived through the evaluation of mechanical properties.

• Land and Housing Review
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• v.14 no.2
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• pp.137-145
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• 2023

In this study, the characteristics such as flowability, bleeding rate, and strength of the CLSM (Controlled Low Strength Material) according to physical properties such as particle size distribution and particulate content of the pond ash were investigated as part of the practical development of technology for CLSM using pond ash. As a result of analyzing the properties of the collected pond ash, it was found that the density and particle size distribution characteristics were different. And that the bleeding ratio did not satisfy the standard in the case of the specimen with a large amount of fly ash and a lot of addition of mixing water. As a result of the compressive strength test, the strength development of 0.5 MPa or more for four hours was found to be satisfactory for the specimens using hemihydrate gypsum with a unit binder amount of 200 or more, and the remaining gypsum showed poor strength development. Although it was determined that landfill coal ash can be used as a CLSM material, it is necessary to identify and apply the physical and chemical characteristics of coal ash buried in the ash treatment plant of each power generation company.

• Journal of Wellbeing Management and Applied Psychology
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• v.7 no.3
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• pp.31-42
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• 2024

Purpose: Open-air dumping is a significant problem in Gilgit City, with limited research analyzing waste generation and its physicochemical impact on the soil. This study aimed to evaluate the effects of open dumping on soil properties and compare them with a controlled site. Research Design, data, and Methodology: Using ANOVA, the study found significant differences in electrical conductivity (EC), soil organic matter (SOM), soil organic carbon (SOC), sand, silt, and clay between the two sites, except for pH. Pearson correlation revealed that pH negatively correlated with EC, sand, and silt, but positively with SOM, SOC, and clay. The control site's mean EC was 6.06 mS/m, whereas the dumping site recorded 8.5 mS/m. EC is inversely related to SOM, SOC, silt, and clay, but directly to sand. SOC and SOM values varied significantly, with notable differences in soil texture components like clay and silt. Results: The research highlights the detrimental effects of unsystematic waste dumping on soil health and its contribution to greenhouse gas emissions, particularly methane, which exacerbates climate change. Conclusion: The study concluded that waste deposition and decomposition significantly impact EC, SOM, SOC, and soil texture, though pH remains unchanged. The unsystematic dumping of solid waste contributes to climate change through methane production, a potent greenhouse gas. To mitigate these impacts, the study recommends regular monitoring, waste prevention, recycling strategies, and continuous training for stakeholders to achieve sustainable development.

• Journal of Bio-Environment Control
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• v.26 no.1
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• pp.7-12
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• 2017

This experiment was conducted to analyze the effect of drainage reuse rate on the growth and fruiting of summer paprika in closed hydroponic cultivation. The experiment was carried out for 25 weeks from March to September 2015 with 0, 20, 30, 50% mixing ratio of waste nutrient solution using non - recycling hydroponic cultivation as a control. As a result, stem diameter of the test was different in the groups 1 and 2, but no difference showed as the group progressed more than 3 groups. L.A.I tended to decrease with increasing drainage mixing ratio. The number of nodes in the 50% reuse test group was 1.4 compared to the control group, but there was no significant difference. The number of harvested nodes was significantly different in the control group (11.1 nodes) and the 50% reuse test group (8.7 nodes), and the harvested nodes tended to decrease as the drainage was reused. The ratio of harvest was also the same as that of the harvesting node, and the control was the highest at 33.2% and the lowest at the 50% reuse test at 27.6%. Relative yields were reduced by 30%, 35% and 45% in the control group in the first group, and this tendency was also observed in the second and fourth groups. However, in the 3 and 5 groups, the production of 50% test group increased by 13% and 5%. The ratio of unmarketable fruit was increased 2%, 4%, 4%, and 7% in 0%, 20%, 30% and 50% reuse test, respectively. In conclusion, if the decrease in yield due to the decline in early growth is carefully managed, even if the imbalance of inorganic ions occurs after the mid-term growth, the growth of the crop will enter into a stable period and the re-use will not be worried about the growth and the yield decrease.