• Geomechanics and Engineering
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• 제16권4호
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• pp.375-384
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• 2018

Unconfined compressive strength (UCS) of high plasticity clayey soil mixed with 5 and 10 % of Portland cement and four chemical agents such as sodium hexametaphosphate, aluminum sulfate, sodium carbonate, and sodium silicate with 0, 5, 10, and 20% concentrations was comparatively evaluated. The individual and combined effects of the cement and chemical agents on the UCS of the soil mixture were investigated. The strength of the soil-cement mixture generally increases with increasing the cement content. However, if the chemical agent is added to the mixture, the strength of the cement-chemical agent-soil mixture tends to vary depending on the type and the amount of the chemical agent. At low concentrations of 5% of aluminum sulfate and 5% and 10% of sodium carbonate, the average UCS of the cement-chemical agent-soil mixture slightly increased compared to pure clay due to increasing the flocculation of the clay in the mixture. However, at high concentrations (20%) of all chemical agents, the UCS significantly decreased compared to the pure clay and clay-cement mixtures. In the case of high cement content, the rate of UCS reduction is the highest among all cement-chemical agent-soil mixtures, which is more than three times higher in comparison to the soil-chemical agent mixtures without cement. Therefore, in the mixture with high cement (> 10%), the reduction of the USC is very sensitive when the chemical agent is added.

• Elastomers and Composites
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• 제51권1호
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• pp.24-30
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• 2016

Sole in the footwear usually modified with foaming agent on the polymer resin to improve the lightweightness and crush-cushion effect. In this study, we investigated rheological properties for polymer resin filled with the different type and concentration of foaming agent, capsule type foaming agent and organo-chemical foaming agent, under the time sweep test. Curing times of each polymer resin with different kind of foaming agent are delayed than reference material (epoxy resin with curing agent). In case of adding capsule type foaming agent, however, there is appropriate concentration to reduce the curing time, relatively. When foaming agent is activated, foaming force inflates the sample in contrast to condensation force of curing and then axial normal force develop to the (+) direction. Interestingly, by increase concentration of foaming agent, there is a specific point to break down the axial normal force development. The reason for this phenomenon is that coalescence of foams induce the blocking of axial normal force development.

• Elastomers and Composites
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• 제49권3호
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• pp.239-244
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• 2014

용매를 사용하지 않고 실리카와 실란커플링제의 반응을 투과 방식 휴리에 변환 적외선 분광법(FTIR)과 열중량 분석법(TGA)을 이용하여 조사하였다. 실란커플링제로 bis[3-(triethoxysilylpropyl) tetrasulfide] (TESPT)를 사용하였다. 미반응 TESPT를 제거한 후, FTIR로 화학 결합 형성을 분석하였고 TGA로 반응한 TESPT 함량을 결정하였다. 커플링제의 함량이 증가할수록 실리카에 결합한 커플링제의 양이 증가하였으나, 커플링제를 과량으로 첨가하면 커플링제 간의 축합반응에 의해 올리고머를 형성하였다. 실리카와 커플링제 그리고 고무의 결합을 확인하기 위하여 개질 실리카와 저분자량 액상 BR을 반응시켜 실리카-커플링제-BR 모델 복합체를 제조하여 화학 결합 형성을 조사하였다. 미반응 고무는 용매를 사용하여 제거하였고 FTIR과 TGA로 분석하였다. BR은 개질 실리카의 커플링제와 반응하여 화학 결합을 형성하였다. 실리카-커플링제-BR의 화학 결합 형성으로 인해 실리카 표면의 극성은 크게 낮아졌고 실리카 입자 크기는 커지는 효과를 보였다.

• 한국군사과학기술학회지
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• 제10권1호
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• pp.123-129
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• 2007

A 2-step process for the safe destruction of chemical wafare agents(agent hydrolysis followed by supercritical water oxidation) was studied to obtain kinetic data for the pilot plant design. This process is simple to operate by using commercial equipments and could be applied as an alternative technology to incineration. Sarin(GB) and sulfur mustard(HD) were hydrolysed in sodium hydroxide and water respectively and their hydrolysates and OPA, which is binary agent for GB were oxidized in a continuous flow supercritical water oxidation system. Destruction efficiencies of the materials were above 99.99% in supercritical water.

• 한국군사과학기술학회지
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• 제10권1호
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• pp.116-122
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• 2007

A 2-step process for the safe disposal of chemical warfare agents(agent hydrolysis followed by incineration In the submerged-quench incinerator) was studied to obtain basic data for the design of pilot plant in the future. Sample materials used for the hydrolysis reaction were sarin(GB), sulfur mustard (HD), and methylphosphonic difluoride(DF). The hydrolysates of these materials were thermally destroyed in a submerged-quench incineration system. Experimental conditions for achieving destruction efficiency of 99.99% in both steps were established and phosphoric acid was recovered from the waste water when destroying DF hydrolysate in the incinerator. Treated water could be reused as process water for the agent hydrolysis.

• 한국유체기계학회 논문집
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• 제17권6호
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• pp.69-73
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• 2014

To predict flow fields and chemical agent dispersion in urban area, wind tunnel experiments was performed. The agent was adopted MS (methyl salicylate) because the real chemical agent is unsafe. The exact concentration of methyl salicylate was generated by the commercial gas generator (STI-2500) and three different obstacle shapes were applied (i.e., rectangular, cylinder and pyramid). The concentration was measured with the qualified ion mobility sensor and gas chromatography. The data necessary for virtual test method of the real chemical agent were obtained.

• Macromolecular Research
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• 제17권10호
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• pp.750-756
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• 2009

Stable, spherical, polystyrene particles were synthesized in ab initio dispersion polymerization by using the poly(methacrylic acid)[PMAA] macro-RAFT agent. The presence of the PMAA macro-RAFT agent on the polystyrene (PS) particles was confirmed by NMR and FTIR spectroscopy. The PS particle size was influenced by the concentration of the RAFT agent and monomer due to the initial nucleation. When the concentration of the PMAA macro-RAFT agent was increased from 2 to 10 wt% relative to the monomer, the average particle size decreased from 2.31 to 1.36 ${\mu}m$, the conversion decreased from 93.3 to 88.9%, the weight-average molecular weight increased from 46,300 to 150,200 g $mol^{-1}$ and the PDI decreased from 2.79 to 1.94, respectively. In particular, the incorporation of 10 wt% of PMAA macro-RAFT agent produced monodisperse PS spheres of 1.36 ${\mu}m$ with a coefficient of variation (CV) of 6.44%. Thus, the PMAA macro-RAFT agent worked as a reactive steric stabilizer providing monodisperse, micron-sized, PS particles.

• 대한방사선기술학회지:방사선기술과학
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• 제43권4호
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• pp.273-280
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• 2020

In this study, the P contrast agent of Iopamidol, which is a nonionic iodide contrast agent most commonly used as a vascular contrast agent in medical institutions, and the O contrast agent of Ioversol, were studied. The physicochemical changes according to the temperature change were compared and analyzed using the Bruker Avance 500MHz Nuclear Magnetic Resonance Spectrometer owned by the Korea Basic Science Institute (KBSI). There was no physical or chemical change in the O contrast medium of Ioversol formulation in temperature change. However, in the P contrast agent of Iopamidol, a doublet peak began to appear in the 1.1 ppm region of the sample at 60℃, and the doublet peak was clearly observed in the sample at 80℃. As a result of this study, 1H-NMR analysis revealed that the P contrast agent of the Iopamidol formulation was dissociated from chemical bonds as it rose to a high temperature of 60℃ or higher, resulting in the formation of foreign substances. It was evaluated that the O contrast agent of Ioversol formulation had physico-chemical stability than the P contrast agent of Iopamidol formulation. As shown in this study, it is necessary to analyze the physical and chemical changes of contrast agents according to various environmental factors.

• 한국식생활문화학회지
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• 제27권6호
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• pp.751-758
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• 2012

This study examined the optimum conditions for producing Jeung-pyun in a faster and efficient way by replacing Takju (traditional way) with a chemical leavening agent for fermentation using dry rice powder instead of wet rice powder. The optimum amount of leavening agent for Jeung-pyun was examined by comparing the moisture content, spring ratio, pore ratio, texture, color value, scanning electron microscopy images and appearance characteristics of Jeung-pyung (con) prepared using traditional fermentation method with those prepared with 4, 5, 6, 7, 8% of the chemical leavening agent. As a result, the 6% leavening agent-added Jeung-pyun showed closest quality results with the traditional Jeung-pyun, and was most preferred. Therefore, 6% leavening agent is the optimum amount for making Jeung-pyun.

• 한국염색가공학회지
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• 제32권1호
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• pp.51-56
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• 2020

This study aims to pursue the multi-functional textile finishing method to detoxify chemical warfare agent by simply treating the well-known antimicrobial agent, chitosan, to cotton fabric. For this purpose, DFP(diisopropylfluorophosphate) was sele cted as a chemical warfare agent simulant and cotton fabric was treated with 0.5, 1.0, and 2wt% chitosan solution in 1wt% acetic acid. DFP decontamination properties of the chitosan treated cotton fabrics were evaluated and compared with the untreated cotton fabric. The chitosan treated cotton fabrics showed better DFP decontamination than the untreated cotton. Decontamination properties of the chitosan treated cotton fabrics improved with the increased chitosan solution used. Especially, the cotton fabrics treated with 2wt% chitosan solution showed 5 times more DFP decontamina tion than the untreated cotton fabrics. This suggested that the chitosan treated fabric has potential to be used as a material for protective clothing with chemical warfare agent detoxifying and antimicrobial properties.