• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.133-140
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• 2008

The purpose of this study is to provide response methods to minimize the damage from chemical terrorism in a naturally ventilated indoor system using several types of dispersion simulations. Three chemical warfare agents such as sarin(GB), phosgene and chlorine gas which have high potential to be used in terror or to be involved with accidents were selected in this simulation. Fire dynamic simulation based on Large Eddy Simulation which is effective because of less computational effort and detailed expression of the dispersion flow was adopted to describe the dispersion behavior of these agents. When the vent speed is 0.005m/s, the heights of 0.1 agent mass fraction are 0.9m for sarin, 1.0m for phosgene and 1.1m for chlorine gas, and the maximum mass fraction are 0.27 for all three agents. However, when the vent speed is increased to 0.05m/s, the heights of 0.1 agent mass fraction become 1.6m for all three agents and maximum mass fraction inside the room increase to 0.70 for sarin, 0.58 for phosgene and 0.53 for chlorine gas. It is shown that molecular weight of the agents has an important role for dispersion, and it is important to install ventilation system with height less than 1.6m to minimize the damage from chemical toxicity.

• Macromolecular Research
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• v.10 no.2
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• pp.127-134
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• 2002

Microporous polypropylene hollow fiber membrane was fabricated from isotactic polypropylene-soybean oil system by melt spinning process. Addition of nucleating agent accelerated the crystallization rate and elevated the crystallization temperature. Nucleating agent increased the number of nuclei and spherulites, which offered more inter-spherulitic amorphous sites for stretching. Benzoic acid, adipic acid, and dibenzylidene sorbitol were selected as nucleating agents, and their characteristics and effects were investigated by thermal and optical analyses. Spherulite growth and micropore formation characteristics were correlated with the kind of nucleating agent. Benzoic acid and adipic acid showed the remarkable nucleating effect, while dibenzylidene sorbitol was less effective than those. Nucleating agents also helped the sample have uniform microporous structure. Increase of nucleating agent composition enhanced the nucleation effect to some extent. Nucleating agents played very important roles in enhancing the membrane porosity and water flux.

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.81-86
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• 1995

Some weight loss accelerating agents, dodecyltrimethylammonium chloride(DTAC), dodecyltrimethylammonium bromide(DTAB), dodecyldimethylammonium chloride(DDBAC), polyoxyethylene(2) dodecylbenzylammonium chloride(PDBAC), and 1-(2-hydroxyethyl)-1-benzyl-2-undecylimidazolinium chloride(AEUIC), were synthesized. As a result of weight loss treatment of the weight loss accelerating agents with NaOH to PET fiber, the increase of weight loss was the order of PDBAC > DDBAC > DTAC > DTAB > AEUIC. Among the weight loss accelerating agents, AEUIC hardly showed weight loss effect, and it was separated into two layer in the NaOH solution at the treatment concentration above 6g/L, but POBAC showed good weight loss effect of 21% that approach almost to a theoretical weight loss, 21.6%, at the concentration above 8g/L.

• Clean Technology
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• v.16 no.3
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• pp.162-171
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• 2010

The objective of this study is to develop cleaning agents for the indoor water supply pipe which is environmentally friendly and suitable for removing scale by using various organic acids, inorganic acids, and some additives. Among various organic acids, oxalic acid, citric acid, and malic acid showed good cleaning efficiency of iron oxides which were main components of the indoor water supply pipe scale. Several cleaning agents were formulated by adding chemical additives into these organic acids and evaluated for removal of iron oxides. In this study, it was found that nonionic surfactants were excellent for the removal of iron oxide scale among various additives. Two types of cleaning agents($F_1$, $F_2$) with comparatively high solvent power for iron oxides were formulated in this study. The cleaning agents $F_1$ made by organic acids and some additives were formulated to be safe and environmentally friendly, but seemed to have disadvantage due to their comparatively low cleaning efficiency of iron oxide than $F_2$. But, the cleaning agents $F_2$ prepared by adding inorganic acid a little to $F_1$ showed comparatively good cleaning efficiency of iron oxide and could be recommended for removing hard scale of iron oxides in the indoor water supply pipe. Thus, it is considered that the formulated cleaning agents should be selected based on the extent of scale in the indoor water supply pipe.

• Clean Technology
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• v.9 no.1
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• pp.9-21
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• 2003

CFC-113 and 1,1,1-TCE which are ozone destruction substances are not used any more in the advanced countries because of Montreal protocol. MC and TCE are now used restrictively at small part of industrial fields in most of countries since they are known to be hazardous or carcinogenic materials. Thus, it is indispensible that the alternative cleaning agents which are environmental-friendly and safe, and show good cleaning ability should be developed or utilized for replacement of the halogenated cleaning agents. Aqueous cleaning agents are evaluated to be promising alternative ones among various alternatives in environmental and economical view point. This study has been carried out as a part of development program of aqueous cleaning agent. First of all, several types of surfactants which are the most important component in aqueous cleaning agents were chosen, and the physical properties, foaming ability, cleaning ability and oil-water separation efficiency of their aqueous solutions were measured and compared for selection of proper type of surfactant in aqueous cleaning agents.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.36-54
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• 1992

The purpose of this study was to compare the shear bond strengths to ground dentin surfaces of four dentinal bonding agents in 193 teeth. Various dentin surfaces treated with four dentin bonding agents were attached with two restorative composite resins. The effectiveness of the bonding were tested by the monitoring the shear bond strength. The shear bond strengths were measured after 2 hours and 24 hours after surface conditioning with four dentin bonding agents. Effects of EDTA, the additive illumination, and sealer treatments without primer on bond strength to dentin surfaces were assessed. In addition the effects of the thickness of specimens ranging from 0.65 mm to 1.95 mm and the ratio of catalyst and base paste on the bond strength of chemical cure composite resin were estimated. The shear bond strength was determined by testing specimens in the Instron universal testing machine (Model No. 1122) at a crosshead speed of 1.0 mm/min. Following condusions were drawn: 1. The highest mean shear bond strengths of chemical cure composite resin to dentin conditioning with dentin bonding agents aged 2 hours were obtained, and then that was decreased with time followed by EDTA treatment. 2. In light cure composite resin, the shear bond strength was increased following dentin conditioning with bonding agents with time, irradiation time and EDTA treatment except in SB group. 3. The thicker the composite resin specimen was, the less the shear bond strength in chemical cure composite resin was. 4. In light cure composite resin, there was a little change in shear bond strength following dentin conditioning with bonding agents. 5. In chemical cure composite resin, the shear bond strength was the highest in the ratio of 1/1 of catalyst and base part. 6. Without a dentin primer, shear bond strength to dentin conditioned only with UB sealer was the highest among four sealers in light cure composite resin.

• Journal of the Korean Society of Safety
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• v.24 no.4
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• pp.40-46
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• 2009

The early identification of thermal hazards associated with a process such as the heats of reaction, exothermic decompositions, and the understanding of thermodynamics before any large scale operations are undertaken. The evaluation of reaction factors and thermal behavior on esterification process in manufacture of concrete mixture agents are described in the present paper. The experiments were performed in the differential scanning calorimetry(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). The aim of the study was to evaluate the thermal stability of single material and mixture in esterification process. We provided the thermal data of chemical materials to present safe operating conditions through this study.

• Archives of Pharmacal Research
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• v.12 no.4
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• pp.276-281
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• 1989

Selective inhibition of seven new PDE inhibitors on cyclic nucleotide PDE isozymes was investigated. Three PDE isozymes (PDE I, II and III) of guinea pig left ventricular muscles were used. All tested agents inhibited cyclic AMP hydrolysis by PDE III IN A concentration-dependent manner. Some agents represented more potent and selective inhibitory effect on PDE III than that of imazodan.

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1027-1028
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• 2005

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1463-1464
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• 2010