• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.105-108
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• 2011

The cycling behavior of $Li_4Ti_5O_{12}$ electrode in the ionic liquid (IL)-based electrolytes containing 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide and a small amount of additive (vinylene carbonate, ethylene carbonate, fluoroethylene carbonate) was investigated. The $Li_4Ti_5O_{12}$ electrode in the IL electrolyte with an additive exhibited reversible cycling behavior with good capacity retention. Electrochemical impedance spectroscopy and FTIR studies revealed that an electrochemically stable solid electrolyte interphase was formed on the $Li_4Ti_5O_{12}$ electrode in the presence of vinylene carbonate and ethylene carbonate during cycling.

• Food Science and Biotechnology
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• 제14권3호
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• pp.334-339
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• 2005

An instrument using thermal probe method was designed to measure thermal conductivity of liquid and solid foods. Thermal conductivity probe was designed with diameter to length ratio of 100 and diameter of 0.51 mm to minimize axial flow effect on thermal conductivity measurement. Thermal conductivities of distilled/deionized water, glycerin, and beef frankfurter meat were measured at $20-80^{\circ}C$. Mean thermal conductivity values of water showed less than 2.0% difference from several reference values without using time correction factor or probe calibration constant. For glycerin, difference was less than 0.7% from reference values at $20-50^{\circ}C$. Mean values of thermal conductivity for beef frankfurter meat ranged from 0.389 to $0.350\;W/m{\cdot}K$ at $20-80^{\circ}C$.

• 소성∙가공
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• 제7권4호
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• pp.364-374
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• 1998

It is the objective of this study to analyze the effect of various process variables on the quality of extruded product and extrusion force for semi-solid extrusion of Al2024 with solid phase structure of globular type by the finite element method. Process variables are initial solid fraction, ram speed, semi-angle of die, and reduction in area. The results of experiment are compared with those of simulation in order to verify the usefulness of the developed finite element program. The flow and deformation of semi-solid alloy are analyzed by coupling by coupling the deformation of porous skeleton and the flow of liquid phase. It is also assumed that initial solid fraction is homogeneous.

• Korean Chemical Engineering Research
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• 제59권2호
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• pp.180-185
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• 2021

한-미 미사일지침 개정으로 우주발사체에 대한 고체추진제 사용 제한이 완전히 해제 됐다. 고체추진제는 1단형 과학로켓 KSR-1과 같이 고체추진제 로켓으로 활용 가능하고, 액체연료 발사체의 추력증강 부스터로도 활용 가능하다. 고체추진제는 액체추진제에 비하여 폭발 위험성이 낮은 장점이 있지만 브라질 알칸타라 발사장 폭발사고와 같이 사고가 일어나면 대형 인명사고로 이어질 수 있다. 이와 같은 대형 인명사고를 예방하기 위해서는 고체추진제의 저장 및 시험 시 최소한의 안전거리에 대한 검토가 사업의 기획단계 부터 검토되고 반영 되어야 한다. 본 논문에서는 발사체 고체추진제를 안전하게 사용하기 위한 최소한의 안전거리를 저장시설과 시험 시로 구분하여 산정 기준 및 사례를 제시하였다.

• 소성∙가공
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• 제8권4호
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• pp.399-406
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• 1999

It is more appropriate to treat that the semi-solid mixture as a single phase material that obeys incompressibility in the global sense and to analyze the liquid flow only locally than the approach based on compressible yield criteria. In the present study, a numerical algorithm of updating the solid volume fraction based on mixture theory has been developed. Finite element analysis of simple upsetting was carried out using the proposed algorithm to investigate the degree of macro-segregation according to friction conditions and compressive strain rates under the isothermal condition. The simulation results were compared to experimental results available in reference to test the validity of the currently proposed algorithm. Since the comparison results show a good agreement it is construed that the proposed algorithm can contribute to the development of numerical analysis of determining the solid volume fraction semi-solid processing.

• 한국세라믹학회지
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• 제49권2호
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• pp.197-203
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• 2012

In this study, in order to improve densification of $La_{0.8}Ca_{0.2}Cr_{0.9}Co_{0.1}O_{3-\delta}$ (LCCC), which is known for one of the most proper candidate interconnector materials in the solid oxide fuel cells, $CaCrO_4$ was prepared via solid oxide synthesis route and added to the LCCC with different amount and particle sizes. As the amount of the $CaCrO_4$ increased, porosity of the sintered samples increased, and the pore size was proportional to the particle size of the $CaCrO_4$. This supports the fact that the $CaCrO_4$ phase forms liquid during sintering and permeate into the matrix leaving behind large pores. Then the liquid reacts with the matrix through the solid solution. However, when the samples were sintered with a slow ramp up rates, the porosity decreased. This is thought to be caused by the progressive solid solution of $CaCrO_4$ before the temperature reach to the melting temperature and forms a fluent amount of liquids. The sintering behavior of the LCCC with the addition of $CaCrO_4$ was analyzed through the transient liquid phase sintering on the basis of the microstructure observation and phase identification by x-ray diffraction.

• 유기물자원화
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• 제22권3호
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• pp.23-32
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• 2014

최근 들어 유기성폐기물의 혐기소화를 이용한 처리(에너지화)가 증가하고 있다. 이에 따라서 혐기소화 후 발생하는 혐기소화폐액의 처리방안에 대한 연구도 증가하고 있다. 그러나, 혐기소화폐액의 특성상 문제로 고액분리에 매우 어려움이 있다.이에 본 연구에서는 CST와 TTF를 이용하여 혐기소화폐액에 대한 응집에 따른 고액분리 특성을 파악하였다. 또한 이러한 문제를 해결하기 위하여 실험실수준의 멤브레인 필터프레스를 제작하고, 혐기소화폐액에 적용하였다. 고분자 응집제는 7192PLUS와 1T60가 가장 적합한 것으로 확인되었으며, 최소 7192PLUS (200 mg/L), 1T60 (100 mg/L)이상의 투입이 필요하였다. 탈수효율을 평가하기 위하여 탈수케이크의 함수율과 탈리여액의 입자성 고형물을 이용하였다. 결과적으로, 멤브레인 필터프스를 이용하여 고액분리 시 입자성 고형물의 제거효율은 97.4%로 높게 나타났으며, 탈수케이크의 함수율은 65%이하로 나타났다.

• 한국대기환경학회지
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• 제34권4호
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• pp.534-541
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• 2018

Concentrations of total particulate matter (TPM), $PM_{10}$ and $PM_{2.5}$ were measured at three different sites based on each different fuel type (solid, liquid and gas) used in thermal power plants operating in Yeosu and Gwangyang National Industrial Complexes during 2017. The highest concentrations of TPM, $PM_{10}$, and $PM_{2.5}$ were observed at the solid fuel facility, and these values were $3.356mg/Sm^3$, $2.342mg/Sm^3$ and $1.834mg/Sm^3$, respectively. The ratio of $PM_{2.5}$ to TPM was the highest value of 54.6% in solid fuel case, and the lowest was 35.7% found in liquid fuel case. As a result of analyzing 9 kinds of metal compound with respect to each particle size, the metal concentration of TPM is higher than those of $PM_{10}$ and $PM_{2.5}$ in all fuel types. Total concentrations of metal elements in TPM by fuel difference are $1.2702mg/Sm^3$ in solid fuel, 0.0603 mg/Sm3 in liquid fuel, and $0.0733mg/Sm^3$ in gas fuel, respectively. Relatively higher total metal concentration in gas fuel than in liquid fuel was found; and this could be higher Cr and Al concentrations in use of gas fuel. As a result of estimating the emission factors of each facility, in case of solid fuel, TPM emissions per electricity production were found to be 0.7080 kt/PJ, followed by liquid fuel and gas fuel. $PM_{10}$ and $PM_{2.5}$ emissions per hour of electricity production were similar to those of TPM.

• 한국레이저가공학회지
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• 제11권1호
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• pp.12-18
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• 2008

Laser micromachining is a promising technique to fabricate the micro-scale devices. However, there remains important challenges to reducethe redeposition of ablated materials around the laser irradiated zone and to get a smooth surface, especially for metal and semiconductor materials. To achieve the high-quality micromachined devices, various methods have been developed. Liquid-assisted micromachining can be a good solution to overcome the previously mentioned problems. During the laser ablation process, the liquid around the solid sample dramatically changes the ablation characteristics, such as ablation rate, surface profile, formation of debris, and so on. In this investigation, we conducted the laser micromachining of Si in various liquid environmental conditions, such as liquid types, liquid thickness. In addition, using nanoscale time-resolved shadowgraphy technique, we observed the ablation process in liquid environments to understand the mechanism of liquid-assisted laser micromachining.

• 생명과학회지
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• 제31권5호
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• pp.502-510
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• 2021

자가 나노유화 약물전달시스템(SNEDDS)은 오일, 계면활성제, 공계면활성제의 균질한 혼합물로서 가벼운 교반에 의해도 에멀전 형성이 가능하고 분산 시 200 nm 이하 범위의 입자 크기를 갖는 나노 에멀전을 형성하는 약물 수송체를 말한다. SNEDDS는 난용성이며 생체이용률이 낮은 소수성약물의 흡수율을 높일 수 있는 뛰어난 가용화 방법으로 알려져 있다. 본 연구에서는 난용성인 티카그렐러에 대한 용해도가 높은 유상으로 MCT oil과, 계면활성제로 Tween 80, 공계면활성제로 Labrafil M1944CS를 사용하여 SNEDDS를 개발하고, 분무건조기술을 이용하여 다양한 다공성의 캐리어에 흡착시켜 고형의 SNEDDS를 제조하였다. 제조된 고형의 SNEDDS에 대하여 물리화학적 특성 및 분말특성을 평가한 후 용출시험을 진행하였다. 본 연구를 통해 얻어진 다공성의 캐리어에 흡착시켜 만들어진 다양한 고형 SNEDDS에서 티카그렐러의 결정형은 무정형으로 변환된 것을 확인할 수 있었다. 또한 제조된 고형의 SNEDDS 조성물들은 모두 원료에 비하여 우수한 용출양상을 나타내는 것을 확인할 수 있었다. 특히 이산화규소를 통해 얻어진 고형의 SNEDDS 조성물의 입자크기와 다분산지수가 제일 작았으며 흐름성과 압축성도 제일 우수하였다. 따라서 이산화규소를 통해 얻어진 고형의 SNEDDS 조성물은 난용성인 티카그렐러의 경구 고형제제화 연구에 적합한 약물 전달 시스템인 것을 확인할 수 있었다.