• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.4 s.112
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• pp.44-51
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• 2005

Paper mills use and discharge lots of water. And so now the papermaking industry could be classified into major water consuming industry In order to analyze the process water network and to establish the mass, water balance of duplex board mill, computer aided simulation was made using water pinch method. Based on the pinch analysis results, reuse of process water, after regenerating by microfilter as much as $140\;m^3/hr$, could be suggested without significant accumulation of contaminants in process water. According to this suggestion about $3000\;m^3/day$ of recycled process water could be sub stituted by regenerated water and consequently $30\%$ of energy cost is expected to be reduced.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.2 s.120
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• pp.9-16
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• 2007

Biological treatment using the activated sludge method and biofilm process has been developed for paper wastewater treatment. It is known that a water treatment using biofilm process has a high efficiency be-cause a great deal of microorganism could adhere to media. It is also known that various plastics such as polyurethane and polyethylene have been used as the media. In this study polyethylene was used as a media and rice straw an additive agent to improve porous and hydrophilic properties of the media for waste water treatment. Porosity and hydrophilic characteristics of polyethylene was increased as rice straw was added to polyethylene. Paper wastewater was then treated with newly developed environment materials. Rice straw showed excellent results in waste water treatment in various media. This environmentally friendly material prepared by polyethylene and rice straw could show similar results to those of a commercial porous polyurethane foam in wastewater treatment.

• Journal of Applied Reliability
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• v.7 no.1
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• pp.31-43
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• 2007

The function of O-ring seals is to prevent leakage during the service life of the components in which they are installed. The life prediction of O-ring is very important at various industry fields. Generally, to evaluated the long-term performance of O-ring in severe environments has applied a life prediction technique based on accelerated life test (ALT). In this work, Accelerated thermal aging test(l20, 130, 140, $150^{\circ}C$) of O-ring was applied for life prediction of O-ring. The property changes after thermal aging test was measured using TGA, DSC, FT - IR, Video Microscope and SEM. Shape parameter and life prediction were obtained using MINITAB program.

• Prospectives of Industrial Chemistry
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• v.17 no.2
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• pp.8-20
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• 2014

나노세공체는 고표면적, 균일한 다공성, 분자크기의 세공구조, 높은 흡착용량, 이온교환 특성, 높은 촉매활성, 분자크기의 형상선택성 등의 특징을 갖기 때문에 촉매 및 흡착제로 나노소재 분야에서 가장 오랫동안 활용되어 왔던 중요한 물질 가운데 하나로 정유 및 석유화학 산업을 비롯한 화학산업과 환경 산업에 광범위하게 사용되고 있다. 본 고찰에서는 결정성 나노세공체 가운데 가장 중요한 제올라이트와 최근 연구가 활발한 하이브리드 나노세공체의 산업적 응용 및 기술개발 동향과 향후 발전 전망에 대해 간략히 기술하였다.

• Toxicological Research
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• v.13 no.1_2
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• pp.95-101
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• 1997

Ethyl carbamate (EC) is a potent teratogen in rodents and is present at low concentration in fermented foods and alcohol beverages. It has been well hypothesized that some metabolic products are responsible for the teratogenic effects of the compound. In the present study, the effects of phenobarbital (PB) on EC-induced embryotoxicity were investigated in SD rats. Six groups were constructed: EC 300 (EC 300 mg/kg/day), EC 600 (EC 600 mg/kg/day), EC 600+PB (EC 600 mg/kg/day and PB 80 mg/kg/day), PB (PB 80 mg/kg/day), DR (dietary restriction, 8 g/day/rat) and a control group. Rats of the EC 600+PB group were pretreated with phenobarbital intraperitoneally for three days to induce cytochrome P450 enzymes, followed by oral administration of EC for two consecutive days. The incidence of fetal deaths in the EC 600+PB group was higher than that of the EC 600 group(42.7 vs. 14.3%). The incidence of fetal realformations in the EC 600+PB group was higher than that of the EC 600 group (external; 7.0 vs. 4.1%, visceral; 31.4 vs. 11.3%, skeletal; 11.1 vs. 6.5%). There was no embryotoxicity in the control, EC 300, PB and DR groups. These results show that the pretreatment with phenobarbital augments EC-induced embryotoxicity in rats, indicating an evidence that metabolic activation by cytochrome P450 may be the major pathway of EC to its embryotoxic forms.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.36-42
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• 2020

In order to investigate the effect of the oxidation process on thermal properties of the pitch, the oxidized pitch was prepared by changing the oxidation temperature. Thermal properties of the pitch were analyzed using thermogravimetric analysis (TGA), and it divided into three sections as A (25~100 ℃), B (250~550 ℃) and C (550~800 ℃) by derivative thermogravimetry (DTG) graph behavior. In the A section, the was reduced because the moisture contained in the pitch was removed. In the B section, as the oxidation temperature increased, the thermal stability of the pitch is improved. Because the degree of aromaticity and molecular weight of the pitch increased with increasing oxidation temperature. In contrast, the results of the C section were shown opposite of B section. Because the introduced C-OH, C-O-C, and C=O bonds were decomposed, and the resulting oxygen compounds induced the combustion reaction of the pitch.

• Tribology and Lubricants
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• v.36 no.3
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• Toxicological Research
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• v.23 no.2
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• pp.159-164
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• 2007

Toxicity screening of a newly developed oral heparin derivative were carried out in 6 male cynomolgus monkeys (Macaca fascicularis), composed of a treatment group and vehicle control group. A newly orally active heparin derivative, developed by Seoul National University, was once given to treatment group at dose of 500 mg/kg. A treatment group did not show any change in body weights, hematological parameters including platelet-related varivables (platelet, PDW, PCT, MPV) and serum biochemical parameters (e.g., AST, ALT, BUN, etc.) for 2 weeks compared with those of vehicle control group. We also confirmed the maximum plasma concentration (Cmax, 1.73 IU/ml) and the time (Tmax, 1 hr) to reach Cmax. The present study will be valuable in the proper interpretation for nonclinical study using cynomolgus monkeys in the development of new drug of heparin derivative.

• Tribology and Lubricants
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• v.30 no.4
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• pp.224-233
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• 2014

We prepared polyester-polyamines to improve the effect of carbon black dispersibility for use in thermal transfer ink, and synthesized polymeric dispersing agents by two-step reactions. In the first step, we made polyester by polycondensing 1,6-hexanediol and adipic acid. The resulting polymers had carboxylic acid, which was linked with polyamine via an acid-base reaction. We then characterized the polyester-polyamine structure by NMR spectroscopy and Fourier transform infrared spectroscopy (FT-IR). We also determined the basic characterizations such as total acid numbers (TAN) (5.0-67.5 mgKOH/g), hydroxyl values (27.1-67.5 mgKOH/g), and molar masses ($M_n=1.6-8.4kg\;mol^{-1}$) for the polyester and total base numbers (TBN) (15.3-57.1 mgKOH/g), hydroxyl values (33.0-79.8 mgKOH/g), and nitrogen contents (1.02-3.48%) for the polyester-polyamine polymers. We thus prepared thermal transfer ink using carbon blacks and the polyester-polyamine dispersing agents, and evaluated the resulting mixtures for printability, adhesive force, storage stability, ink appearance, ink gloss, and processability. These mixtures showed significant dispersibility for carbon black in the ink. Thus, we concluded that the dispersibility of the polymeric materials depended on the polyamine structure and the hydrophilicity-hydrophobicity distribution of the polymeric dispersants.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.291-298
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• 2013

Conjugated linoleic acid methylester was synthesized through isomerization of linoleic acid methylester by using heterogeneous catalysts. As for heterogeneous catalysts, Ni supported zeolite type catalysts were used. H zoelite Y (HY) were ion exchanged with KCl aqueous solution to synthesize K zeolite Y (KY), and with impregnation method, Ni supported zeolite catalysts were synthesized. Catalysts were used after pre-treatment by using hydrogen. HY catalysts showed a high conversion at low temperatures; but a low selectivity for conjugation reaction. KY catalysts showed a low conversion at low temperatures; but a similar conversion with HY catalysts at high temperatures while a high selectivity at low temperatures. As a result, 4 wt% Ni/KY720 recorded the high conjugation yield of 63.4% at 220.