Al–Mg co-doped ZnO thin films were fabricated by a sol–gel spin-coating process to investigate the effect of dopant ratio on their structural, electrical, and optical properties. The total dopant concentration was fixed at 3 mol%, while the Al-to-Mg ratio was systematically varied in AlxMg0.03-xZn0.97O (0 ≤ x ≤ 0.03). X-ray diffraction analysis showed that the films maintained a hexagonal wurtzite structure with a preferred (002) orientation up to an Al concentration of 1.5 mol%, whereas higher Al contents resulted in a degradation of crystallinity due to exceeding the solid solubility limit of Al in the ZnO lattice. Hall effect measurements revealed a decrease in carrier mobility with increasing Al content, attributed to enhanced ionized impurity scattering, while the carrier concentration and electrical conductivity reached optimal values at an Al–Mg co-doping ratio of 1.5 mol%–1.5 mol%. All films exhibited high optical transmittance in the visible region, with the highest average transmittance of approximately 83% observed at the same composition. These results demonstrate that controlling the Al/Mg dopant ratio is crucial for optimizing the performance of ZnO-based transparent conducting oxide thin films.

In this study, numerical modeling on the gas flow and off-gases in the low temperature carbonization furnace for carbon fiber was analyzed. The furnace was designed for testing carbonization process of carbon fibers made from various precursors. Nitrogen gas was used as a working gas and it was treated as an incompressible ideal gas. Three-dimensional computational fluid dynamics for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The off-gas mass fraction and cumulative emission gas of species were incorporated into the CFD analyses by using the user defined function(UDF). As a results, during the carbonization process, the emission of CO2 was the dominant among the off-gases, and tow moving made the flow in the furnace be uniform.

In this study, gas flow pattern and temperature distribution in a laboratory scale low temperature furnace for carbonization were numerically analyzed. The furnace was designed for testing carbonization process of carbon fibers made from polyimide(PI) precursor. Nitrogen gas was used as a working gas and it was treated as an ideal gas. Three-dimensional computational fluid dynamics analysis for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The results showed that more uniform velocity profile and axisymmetric temperature distribution could be obtained by varying mass flow rate at the inlets.

산업장에서 사용되는 산업용 세척제는 대부분 합성계면활성제를 사용하기 때문에 사람에게 장기간 노출될 경우 피부 갑작자극 면역기 저하를 통해서 비염, 천식, 아토피 등을 유발할 수 있으며, 기계에는 부식성에 의해 기계의 이상을 가져올 수 있다. 가정이나 제조업체에서 대량으로 방출되는 폐식용유를 이용하여 산업용 세척제를 만들 경우 폐자원의 재활용과 수계유입시 발생하는 환경오염을 차단할 수 있다. 또한, 폐식용유는 식물성유지가 대부분의 성분으로 유해화학물질이 거의 없으며 pH가 약알칼리성이기 때문에 산업용 계면활성제로 제조할 경우 인체에 무해하고 기계에 대한 부식성도 없는 특징을 가질 수 있다. 따라서, 본 연구의 목적은 산업용 세척제의 재료로 폐식용유를 사용하여 에스테르의 가수 분해에 의해 카르복실산과 알코올을 생성하는 비누화 반응을 촉진하고 유용성 미생물과 발효기술 등을 접목하여 산업용 세척제를 개발하는 것이다. 이렇게 개발된 세척제는 평가 항목으로 표면장력, pH, 수분 및 휘발성 물질, 메틸알콜, 형광증백제, 석유 에테르 가용성분, 생분해성, TOC, 중금속(As, Pb 등), 부식성 등에 대한 성능을 분석 및 평가하고 생산된 시제품을 산업현장에서 사용하여 제품의 현장 적용성을 확인함으로써 성능의 우수성과 단점을 보완하여 제품에 반영하고자 하였다.