• Resources Recycling
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• v.30 no.2
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• pp.53-60
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• 2021

Leaching experiments from single metal and metallic mixtures were conducted to develop a process for the recovery of cobalt, copper, and nickel in spent lithium ion batteries. Inorganic and organic acid solutions without oxidizing agents were employed. No copper was dissolved in the absence of an oxidizing agent in the leaching solutions. The leaching condition to completely dissolve single metal of cobalt and nickel was determined based on acid concentration, reaction temperature and time, and pulp density. The leaching condition to dissolve all of cobalt and nickel from the metallic mixtures was also obtained. Leaching of the metallic mixture with methanesulfonic acid led to selective dissolution of cobalt at low temperatures.

• Polymer(Korea)
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• v.34 no.4
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• pp.289-293
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• 2010

Periodic mesoporous organosilicas (PMO) were synthesized using bis(triethoxy silyl) ethane (BTEE) as the precursor and dodecyl trimethyl ammonium bromide(DTMA), cetyl trimethyl ammonium bromide(CTMA), and octadecyl trimethyl ammonium bromide(ODTMA) as the templating agents. The surface area and pore volume of PMO decrease with the increasing of chain length of templating agents. However, the chain length of templating agents almost has no effect on the pore diameter of PMO. From the XRD and the DSC experiments, we found that the chain length of surfactants using as the templating agents has an effect on the melting transition of polyethylene. But it has no effect on the melting transition of poly(ethylene oxide). The results of TGA prove that the thermal decomposition temperature of polymer which was penetrated into PMO was increased.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.232-234
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• 2012

높은 투명성과 우수한 자외선 차단성을 갖는 금속산화물 나노입자와 유기계 자외선 차단제 및 폴리머와의 하이브리드화를 통한 고기능 입자를 합성하기 위하여 산화티탄(TiO2)에 유기 자외선차단제를 도입 하였다. 그 결과 UVB영역과 UVA영역을 동시에 차단할 수 있는 유무기 하이브리드화 자외선차단제를 제조하였다.

• Biomedical Science Letters
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• v.12 no.4
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• pp.451-455
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• 2006

It is demonstrated that inorganic mercury has cytotoxic effect on glial cells. Recently, oxygen radicals is involved in methylmercuric chloride (MMC)-induced cytotoxicity. But, the toxic mechanism of MMC is left unknown. The purpose of this study was to examine the cytotoxicity of MMC on $C_6$ glioma cells. The cytotoxicy was measured by cell viability using XTT assay in $C_6$ glioma cells. Colorimetric assay is regarded as a very sensitive screening method for the determination of the cell viability on various agents. In this study, MMC decreased cell viability according to the dose- and time dependent manners after $C_6$ glioma cells were grown with various concentrations of MMC for 48 hours. In the protective effect of allopurinol on MMC-induced cytotoxicity, allopurinol was effective in the prevention of MMC-induced cytotoxicity in these cultures. These results suggest that MMC has highly cytotoxic effect on $C_6$ glioma cells by the decrease of cell viavility, and free radical scavenger such as allopurinol was effective on organic mercury-induced cytotoxicity in these cultures.

• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.8
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• pp.1060-1068
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• 1998

The effects of various catalysts and softners on the anti-crease finish of ramie with glyoxal were investigated. A number of metal salts commonly used as Lewis acid catalysts in DP finishing of cotton with formaldehyde and N-methylol agents were screened for glyoxal treatment of ramie fabric. Various organic and inorganic acids were mixed with Lewis acid catalyst as co-catalysts to improve catalytic activity. As a result, the combination of aluminum sulfate and citric acid was proven highly effective in catalyzing the crosslinking of ramie cellulose by glyoxal under lower curing temperature. With a mixed catalyst, performance properties, such as whiteness and tearing strength as well as wrinkle recovery of treated ramie fabric were improved as compared with that treated with aluminum sulfate alone. Additional improvement of tearing strength and wrinkle recovery was achieved by applying silicons softner in the treatment bath.

• Tuberculosis and Respiratory Diseases
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• v.71 no.5
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• pp.317-321
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• 2011

Occupational lung disease (OLD) is a group of lung diseases caused and/or aggravated by organic and inorganic inhaled dust, fumes, and mist. OLD can develop under various occupational situations. Therefore, occupational history should be considered when evaluating respiratory symptoms. Once OLD is developed, it may not be treated and may even progress after exposure to the causative agents has stopped. The best ways to treat OLD are prevention and early detection by controlling the working environment and conducting regular surveillance of workers. Common OLDs in Korea are coal worker's pneumoconiosis, asbestos-related diseases, and occupational asthma. Recent aspects of these common OLDs in Korea will be described based on recently published studies.

• Advances in materials Research
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• v.4 no.4
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• pp.207-214
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• 2015

It has been reported in the technical literature that orotic acid can be used in order to induce improved crystallization of biodegradable and biocompatible polymers like poly(L-lactic acid), polyhydroxybutyrate and poly(hydroxybutyrate-co-hydroxyhexaonat). The expected advantage of the changed crystalline structure is a reinforcing effect of the polymers. A lot of papers reported about the application of inorganic and organic agents for acceleration of heterogeneous nucleation. This study reports on an attempt to use orotic acid as appropriate non-toxic nucleating agent for improving mechanical properties of isotactic polypropylene. Special attention is given to demonstrate the effect of nucleation in a typical melt spinning process in order to improve the mechanical properties. The effects were demonstrated using rheology, thermal analysis and tensile testing.

• Journal of the Korea Organic Resources Recycling Association
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• v.5 no.2
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• pp.17-28
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• 1997

To study the possibility of agricultural utilization of industrial wastewater sludge, the changes of the substances, such as temperature, pH, inorganic and organic matter, the form of nitrogen, fatty acid and the population number of microorganisms during composting periods were investigated. Temperature and $CO_2$ generation were the highest in the second day of composting peroids, and then were gradually fallen. And they were similar to room temperature after the sixth day of composting periods. C/N ratio was a little increased as time went by. pH value was not changed in early composting periods and then pH had been gradually decreased since it was rapidly increased. It was in the range of 8.7~8.8 in late composting periods. The contents of $P_2O_5$, $K_2O$, CaO, MgO and Fe were a little increased and that of ${SO_4}^{2-}$ was increased with 62~67% in late in comparing with early composting periods. The contents of ether extracted materials, water soluble polysaccharides, hemicellulose and cellulose were decreased but that of resins and lignin were not changed during composting periods. The contents of total and organic nitrogen were decreased but that of inorganic nitrogen was increased during composting periods. The population number of microorganism during composting periods was too much changed according to the kinds of bulking agents and microorganisms, and the composting periods.

• Journal of Soil and Groundwater Environment
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• v.14 no.1
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• pp.78-82
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• 2009

In this study, the feasibility of soil washing and soil flushing was investigated to treat Zn-contaminated railroad soil. Various organic acids including ethylene diamine tetraacetic acid (EDTA) and citric acid as well as inorganic acids such as hydrochloric acid (HCl) and phosphoric acid were tested to evaluate washing efficiency. Generally, inorganic acid showed higher removal efficiency compared to organic acids. Particularly, EDTA, well known as the most effective washing agent for removal of heavy metals from soil, was not efficient to remove zinc in this study. Among washing agents tested in this study, HCl was the most effective. However, it is not effective to use HCl solution over 0.1 M concentration. Sequential process using HCl was effective to enhance the removal efficiency of zinc. In column test, the removal efficiency of Zn was 27%. Accordingly, it is feasible to treat Zn-contaminated railroad soil using soil washing or flushing with HCI.

• Composites Research
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• v.36 no.2
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• pp.126-131
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• 2023

Growing environmental concerns regarding pollution caused by conventional plastics have increased interest in biodegradable polymers as alternative materials. The purpose of this study is to develop a 100% biodegradable nanocomposite material by introducing organic nucleating agents into the biodegradable and thermoplastic resin, poly(lactic acid), to improve its properties. Accordingly, cellulose nanofibers, an eco-friendly material, were adopted as a substitute for inorganic nucleating agents. To achieve a uniform dispersion of cellulose nanofibers (CNFs) within PLA, the aqueous solution of nanofibers was lyophilized to maintain their fibrous shape. Then, they were subjected to primary mixing using a twin-screw extruder. Test specimens with double mixing were then produced by injection molding. Differential scanning calorimetry was employed to confirm the reinforced physical properties, and it was found that the addition of 1 wt% CNFs acted as a reinforcing material and nucleating agent, reducing the cold crystallization temperature by approximately 14℃ and increasing the degree of crystallization. This study provides an environmentally friendly alternative for developing plastic materials with enhanced properties, which can contribute to a sustainable future without consuming inorganic nucleating agents. It serves as a basis for developing 100% biodegradable green nanocomposites.