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자외선에 의해 자외선 차단 효율이 상승하는 선크림 제형 개발
최민성 ( Minsung Choi ),조형진 ( Hyeongjin Cho ),송경희 ( Kyunghee Song ),송승진 ( Seungjin Song ),강내규 ( Nae-gye Kang ),박선규 ( Sun-gyoo Park ) 대한화장품학회 2019 대한화장품학회지 Vol.45 No.2
자외선에 의해 자외선 차단 효율이 상승하는 선크림에 대한 연구를 수행하였다. Ethylhexyl methoxycinnamate (OMC)는 가장 널리 쓰이는 자외선 차단제이고, OMC에 대한 광안정성 연구는 오랫동안 수행되어왔다. OMC는 자외선에 의해 trans구조가 cis구조로 변하거나, dimer를 비롯한 광반응물을 생성하여 자외선 차단효율이 떨어진다고 알려져 왔다. 하지만 본 연구에서는 OMC나 isoamyl p-methoxycinnamate (IMC)와 같이 메톡시신나메이트 구조를 공유하는 자외선 차단제들이 실제 사용조건과 유사한 조건에서 자외선에 노출 시키고 잘 설계된 실험 방법으로 in vitro SPF 수치를 측정하였을 때 오히려 자외선 차단 효율이 증가하는 것을 발견하였다. 이것은 자외선에 의해서 생성된 광반응물과 OMC간의 π-π stacking을 통한 π-π* 전이 에너지 변화(UV activated transition) 때문인 것으로 생각된다. 이 발견을 선크림 개발에 적용하기 위해서는 함께 사용되는 에몰리언트의 극성 및 상용성을 적절히 고려해야 한다. 상용성이 좋은 극성 에몰리언트를 포함하면 자외선에 의해 OMC가 광반응물을 생성하지 않기 때문에 발견의 효과가 감소하는 것으로 보인다. 이러한 작용 기전(UV activated SPF boosting)을 바탕으로 상업용 수준의 선크림을 제조하여 평가해보았다. 그 결과 자외선(2 MED)에 노출되었을 때 in vitro SPF 수치는 50.69에서 72.33으로 42.69%로 증가하였고 in vivo SPF 평가에서는 53.7을 얻어 같은 조건의 대조군의 선크림(SPF 34.4 이하) 대비 56.10% 이상 높게 측정되었다. 따라서 OMC와 IMC가 특정 조건에서 UV sensor처럼 작용하여, 자외선에 노출 되었을 때 자외선 차단 효율을 높일 수 있는 선크림을 제조할 수 있었다. This study is investigated sunscreen formulation that enhances UV absorption efficiency by UV light. Ethylhexyl methoxycinnamate (OMC) is one of the most common UV filters. Many studies have been conducted about photostability of OMC. It is well known that under the UV exposure, trans-OMC could turn to cis-OMC, or produce various photoproducts including its dimers. Those chemical structure changes were understood as the reason of a decrease in UV absorption efficiency upon UV exposure. However, it was found that OMC and isoamyl p-methoxycinnamate (IMC) could even enhance its UV absorption efficiency when it was exposed to UV light in an environment similar to actual use. In order to develop sunscreen formulation that enhances UV absorption efficiency by UV light, emollient with high polarity and compatibility should be avoided from the formular. Those emollient seemed to prevent OMC or IMC from producing photoproducts under UV light. Finally, a sunscreen formulation (UV sensing SPF boosting formular) enhancing UV absorption efficiency by UV was developed by the UV activated SPF boosting technology, and the effect of the sunscreen was evaluated. in vitro SPF of the sunscreen was increased from 50.69 to 72.33 when it was exposed to UV light and its in vivo SPF (53.7) was 56.10% higher than that of the control sunscreen (below 34.4).
미분탄 이중 스월화염에서 스월강도 및 석탄 입경 변화 영향 연구
최민성(Minsung Choi),성연모(Yonmo Sung),이상민(Sangmin Lee),문철언(Cheoreon Moon),최경민(Gyungmin Choi),김덕줄(Duckjool Kim) 한국연소학회 2014 KOSCOSYMPOSIUM논문집 Vol.2014 No.11
The present work focuses on the analysis of the pulverized coal combustion aerodynamics of the dual swirl burner by the control of the swirl-modes such as the outer swirl intensity (OSI). The detailed structure of pulverized coal swirling flames with swirl-mode was studied experimentally by particle image velocimetry and local flame colors based on OH<SUP>*</SUP>, CH<SUP>*</SUP>, and C₂<SUP>*</SUP> radicals. For all co-swirling conditions, the internal recirculation zone (IRZ) was observed near the inner shear layer with respect to the processing vortex core structure. Furthermore, a co-rotating vortex in the outer shear layer and the exhaust tube vortex (ETV) along the central axis were observed. The intensity of CH<SUP>*</SUP> signal was higher with small coal particle size, conversely, the size of the distribution of the CH<SUP>*</SUP> signal becomes larger. Therefore, the control of the aerodynamics with changing swirl intensities may play an important role in improving both environmental and combustion performances.
미분탄 스월버너에서 석탄/바이오매스 혼소시 바이오매스 입자 크기가 화염구조 및 연소특성에 미치는 영향
박예슬(Yeseul Park),최민성(Minsung Choi),리신줘(Xinzhuo Li),정찬호(Chanho Jeong),이지훈(Lee Jihoon),최경민(Gyungmin Choi) 한국연소학회 2020 한국연소학회지 Vol.25 No.4
The flame structure and combustion characteristics of co-firing coal and LPG with different sizes of biomass were investigated in a dual swirl pulverized coal burner by using a high-speed camera with bandpass filter and PIV system. Three sizes of spent mushroom compost (<45, 45~90, 90~150 ㎛) were cofired with pulverized coal (45~90 ㎛) at a blending ratio of 20%. When the biomass of the same size with coal was used, the turbulence intensity had the highest uniformity while other cases exhibited locally strong turbulent intensity. The combustion using <45 ㎛ biomass was terminated early compared to other conditions, whereas the reaction region was the widest for 45~90 ㎛ biomass. The flame had uniform turbulent intensity with wide and strong reaction when the biomass size was equal to that of coal. When using 45~90 ㎛ of biomass, high velocity was maintained in the overall region and CH<SUP>*</SUP> radical was observed in a wide region with the highest radical intensity.
미분탄 스월버너에서 PKS와 석탄 혼소가 화염 구조에 미치는 영향
신민호(Minho Shin),성연모(Yonmo Sung),최민성(Minsung Choi),이광수(Gwangsu Lee),최경민(Minsung Choi),김덕줄(Duckjool Kim) 한국연소학회 2016 한국연소학회지 Vol.21 No.4
Flame structure of co-firing coal and palm kernel shell (PKS) was investigated in a pulverized coal swirl burner by particle image velocimetry (PIV). The pulverized coal swirl flame is operated with a PKS blending ratio of 10%, 20%, and 30%. For all operating conditions, flame structures such as internal recirculation zone (IRZ), outer recirculation zone (ORZ), and exhaust tube vortex (ETV) were observed. In the center of flame, the strong velocity gradient is occurred at the stagnation point where the volatile gas combustion actively takes place and the acceleration is increased with higher PKS blending ratio. OH radical shows the burned gas region at the stagnation point and shear layer between IRZ and ORZ. In addition, OH radical intensity increases for a co-firing condition because of high volatile matter from PKS. Because the volatile gas combustion takes place at lower temperature, co-firing condition (more than 20%) leads to oxygen deficiency and reduces the combustibility of coal particle near the burner. Therefore, increasing PKS blending ratio leads to higher OH radical intensity and lower temperature.