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철-크롬 산화환원흐름전지에서 Nafion막의 철-크롬 Crossover
김영숙,오소형,김은비,김다영,김성지,추천호,박권필,Kim, Young-Sook,Oh, So-Hyeong,Kim, Eunbi,Kim, Dayoung,Kim, Seongji,Chu, Cheun-Ho,Park, Kwonpil 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.1
산화환원흐름전지(Redox Flow Battery, RFB)는 대용량 에너지 저장장치로 바나듐 산화환원흐름전지가 대표적인 RFB인데, VRFB는 고가인 점이 문제다. 철-크롬RFB는 저가의 활물질을 사용해 경제적인 점이 장점인데, 성능이 낮은 점이 해결해야할 과제다. 낮은 성능의 한 원인이 활물질의 크로스오버인데, 본 연구에서 철과 크롬 이온의 Nafion 막 크로스오버 및 Nafion 막의 안정성에 대해 실험하였다. 철과 크롬이온의 Nafion 막 투과도는 각각 $5.5{\times}10^{-5}$, $6.0{\times}10^{-5}cm^2/min$ 이었다. Nafion 막에서 바나듐 이온의 투과도 $2.9{\times}10^{-6}cm^2/min$ 보다 18.9~20.7배 높아 철과 크롬 이온의 Nafion 막 크로스오버가 성능 저하의 한 원인임을 보였다. 온도 증가에 따라 크로스오버가 급증(활성화 에너지 38.8 kJ/mol)하므로 낮은 온도에서 구동하는 것이 크로스오버에 의한 성능감소를 저하시키는 방법임을 나타냈다. Nafion막은 3M HCl용액에서 비교적 안정적이었다. The redox flow battery (RFB) is a large-capacity energy storage equipment, and the vanadium redox flow cell is a typical RFB, but VRFB is expensive. Iron-chrome RFBs are economical because they use low-cost active materials, but their low performance is a urgent problem. In this study, the crossover of iron and chromium ion through Nafion membrane and the stability of Nafion membrane in HCl solution were investigated. The permeability of iron and chrome ion through Nafion were $5.5{\times}10^{-5}$ and $6.0{\times}10^{-5}cm^2/min$, respectively, which was 18.9~20.7 times higher than that of vanadium ion ($2.9{\times}10^{-6}cm^2/min$). The crossover of iron and chromium ions were shown to be a cause of performance decrease in Iron-chrome RFB. As the temperature increases, the crossover increases rapidly (activation energy 38.8 kJ/ mol), indicating that operation at low temperature is a methode to reduce the performance loss due to crossover. Nafion membranes were relatively stable in 3 M HCl solution.
백반증 환자에서 PUVA 치료후 나타난 부작용에 대한 임상적 고찰
김영숙,강형철 ( Young Sook Kim,Hyung Chul Kang ) 대한피부과학회 1997 大韓皮膚科學會誌 Vol.35 No.4
Background: Oral of topical psoralen photochemotherapy is the most popular arid efficacious treatment, available for repigmentation of vitiliginous patches. However this therapy is often used for prolonged periods and various types of pigmentary changes can be observed and sometimes, may be carcinogenic. The safety of PUVA therapy has been an issue of debate. Objective .' The purpose of the study was to describe in more detail the complications of PUVA treatment and to investigate a possible relation with multiple factors. Patients and Method: We studied 137 vitiligo patients who received PUVA therapy(using oral 8-MOP) for more than six months in our department between March 1990 and June 1996. Resulte . The results are summarized as follows 1. Among 137 cases of vitiligo, the numbers of male and female patients were 40(29.2%) and 97(70.8%) respectively. The mean age at the start of PUVA was 39 years and the mean duration of treatment was 31 months. There were no patients with skin type I and II. Forty cases had skin type III, 68 skin type IV, 29 skin type V. 2. Acute side effects were nausea(35.8%), pruritus(32:8% ), erythema(30.7%), headache(21.2 %), dizziness(18.8%), burning sensation(16.8%), fatigue(8.8%) and the Koebner phenomenon(1.5 %). These are all reversible and disappear on discontinuation of treatment.. 3. PUVA-induced pigmentary changes were PUVA lentigines(39 cases;26.3%), hypopigmented confetti macules(36 cased;26.3%), mottling(31 cases,22.6%), nail pigmentation(8 cases,5.8%) and PUVA keratosis(7 cases;5.1%) 4. The mean cumulative UVA dose was 1833J/cm and the mean number of treatments was 171. In the high-dose group and the patients who had the most number of treatments, we observed an increased number of patients with PUVA lentigiens and mottling. However, no relationship was observed between the development of PUVA-induced pigmentary changes and sex or age at the start, of PUVA or in relation to skin type. 5. We did not see any patients with melanoma, nonmelanoma skin cancer or systemic cancer. Conclusion : Long term exposure to PUVA significantly increases chronic clinical side effects of PUVA. Therefore carefuI clinical follow-up of patients who receive long term PUVA therapy in necessary. This risk shoud be considered in selection of treatment. (Kor J Dermatol 1997;35(4): 684-692)