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미세먼지로 인한 온실 피복재 투과율 저하 실험모델 개발
이종혁 ( Jonghyuk Lee ),정영준 ( Youngjoon Jeong ),이상익 ( Sangik Lee ),서병훈 ( Byunghun Seo ),김동수 ( Dongsu Kim ),홍은미 ( Eunmi Hong ),이승재 ( Seungjae Lee ),이재한 ( Jaehan Lee ),최원 ( Won Choi ) 한국농공학회 2020 한국농공학회 학술대회초록집 Vol.2020 No.-
최근 국내외로 급속한 산업화로 인해 황사 및 미세먼지 발생 횟수가 증가하고 있으며, 이러한 미세먼지는 비닐온실의 투과율을 저하시켜 시설 작물의 생육 환경을 저해한다. 본 연구에서는 미세먼지 발생으로 인한 온실 피복재 투과율 저하도를 구명하고, 온습도 환경에 따른 미세먼지 흡착율을 평가하기 위해 축소실험모델을 개발하였다. 모델은 1개의 미세먼지 발생환경 재현 챔버와 미세먼지 발생장치, 온습도 및 미세먼지 측정 모니터링 센서를 포함한 컨트롤러로 구성되었다. 미세먼지 발생장치의 시료 투입구에 공압펌프를 활용하여 일정 간격으로 미세입자가 주입되며, 정량 투입을 위한 물리적 장치가 고안되었다. 또한 미세먼지 발생장치 내 싸이클론 발생기와 필터를 설치하여 챔버 내 미세먼지의 입경별 투입을 고려하였다. 미세먼지 시료는 입경 분포가 0.97 - 22.00 ㎛로 이루어진 Arizona test dust (A1 Ultrafine)을 사용하였으며, 온실 설계 시 가장 많이 활용되는 폴리에틸렌 (PE) 피복재를 대상으로 투과율 저하도를 분석하였다. 챔버내 온·습도 환경을 조절하며 미세먼지 흡착율에 따른 비닐시편의 투과율 저하도를 비교하였다.
The properties of porous silicon as a therapeutic agent <i>via</i> the new photodynamic therapy
Lee, Chongmu,Kim, Hojin,Cho, Youngjoon,Lee, Wan In Royal Society of Chemistry 2007 Journal of materials chemistry Vol.17 No.25
<P>Photodynamic therapy (PDT) is a very useful approach for cancer treatment, but it has a few short-term and long-term side effects arising from reactive oxygen species (ROS) generation. Recently a new photodynamic therapy (PDT) based not on the ROS generation capability of photosensitizers but on the heat generation capability of carbon nanotubes (CNT) combined with a near-infrared (NIR) light irradiation technique has received significant attention. Our experimental results show that PSi can also be utilized as a therapeutic agent that generates sufficient heat to kill cancer cells without toxicity. The surface temperature of PSi increases as high and as quickly as that of CNT, but PSi was found to produce a smaller amount of ROS than CNT during NIR light irradiation. In addition, we developed a new method to effectively measure the amount of the ROS produced by nanomaterial photosensitizers including porous silicon (PSi) and CNT. The analysis results show that this method is reliable and reproducible.</P> <P>Graphic Abstract</P><P>Porous silicon can be utilized as a therapeutic agent that generates sufficient heat to kill cancer cells with minimal reactive oxygen species generation upon exposure to near-infrared light. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b700892a'> </P>
Proliferation Resistance Features for Molten SR Using 233U-232Th Fuel Cycle
Youngjoon Lee,Sunyoung Chang 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
Liquid-fueled Molten Salt Reactors (MSRs) do not contain their fuel in assemblies. It is then not possible to perform traditional item counting and visual accountability of the salt fuel. These facilities are closer to bulk accounting facilities, such as reprocessing plants, and require inventory determinations based on measurements of the actinide content of salts. This can be problematic due to the difficulty of sampling and the destructive analysis of actinide-containing molten salts. Some problems arise from the unique combination of high temperature and high radiation environments present in molten salt fuels. Another challenge is the continuous change in the isotopic concentration of fuel salts due to burn-up, conversion, plating out, and online chemical processing. There is a potential for fuel stocks outside the reactor containment vessel in on-site salt processing. In terms of proliferation resistance of 233U-232Th fuel cycle, the nuclide 232U is an important nuclide in thorium fuel cycle from the standpoint of proliferation resistance, because its daughter Thallium (208Tl) is a strong gamma (2.6 MeV) emitter. The hard gamma ray is not only barrier from to nuclear material theft, but also an effective means of detecting lost fissile material. However, there is a theoretical weakness in obtaining pure 233U at the core of the initial two weeks with a concentration of 232Pu less than 1,000 ppm. Therefore, Pu separation process is one of the most sensitive parts in online reprocessing facility. The decision to use a fertile blanket should also be based on proliferation risk considerations in addition to operational parameters. MSRs can be designed without a separate fertile blanket, which should be considered. In the case of the MSFR, even if fertile blankets are used, the production of 232U is large enough to make difficult the utilization of blankets for proliferation purpose. For the liquid-fueled MSRs without fissile materials separations, many of the observations from the previous section apply, except salt processing is minimized. The reactors will still need some method of estimating total actinide content. These reactor designs reduce proliferation risk for the reactor by not separating any actinides during operation.