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집시형 태양열 흡수기의 Transient 열전달 특성에 대한 수치해석 연구
이주한(Juhan Lee),서주현(Joohyun Seo),오상준(Sangjune Oh),이진규(Jinkyu Lee),서태범(Taebeom Seo) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
A numerical and experimental studies are carried out to investigate the transient heat transfer characteristics of 5㎾th dish-type solar air receiver. Measured solar radiation and temperatures at several different locations are used as boundary conditions for numerical simulation. Many parameters' effects (reflectivity of the reflector, the thermal conductivity of the receiver body, transmissivity of the quartz window, etc.) on the thermal performance are investigated. Discrete Transfer Method is used to calculate the radiation heat exchange in the receiver. A transient heat transfer model is developed and the rate of radiation, convection and conduction heat transfer are calculated. Comparing the experimental and numerical results, good agreement is obtained. Using the numerical model, the transient heat transfer characteristics of volumetric air receiver for dish-type solar thermal systems are known and the transient thermal performance of the receiver can be estimated.
마이크로파 추출공정에 의한 옥수수속대 생리활성물질 추출조건 최적화
정현진(Hyunjin Jung),민보라(Bora Min),김승기(Seungki Kim),조재민,서주현(Joohyun Seo),김진우(Jin Woo Kim) 한국생물공학회 2018 KSBB Journal Vol.33 No.1
This study investigated the optimization of extraction of bioactive compounds from corncob using various microwave extraction conditions. The central composite design (CCD) was applied to optimize microwave power, extraction time, and sulfuric acid concentration. Among tested variables, microwave power and extraction time showed significant effects on total polyphenol compounds (TPC) as well as flavonoid contents. However, the change in concentration of sulfuric acid only had a significant effect on extraction of flavonoid. The optimum conditions of microwave-assisted extraction (MAE) were 644 w, 66.3 sec, and 0.03 mol of sulfuric acid, and in this condition, maximum concentrations of 7.91 mg GAE/g DM of TPC and 0.79 mg QE/g DM of flavonoid were extracted. Antimicrobial activity of extracts from MAE, hotwater extraction (HWE), and ultrasound-assisted extraction (UAE) were measured by disk diffusion assay. HWE and UAE had no antimicrobial effects, whereas the antimicrobial effect of MAE has been identified. In conclusion, MAE was found to be effective in extracting bioactive compounds, including TPC and flavonoid from corncob despite short extract time and low extraction under 84 sec and 120℃, respectevely.