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폐기물의 퇴비화 과정중 물질 변화 : 3. C/N 율 변화 3. Changes of C/N Ratios in Compost
서정윤 한국환경농학회 1989 한국환경농학회지 Vol.8 No.1
퇴비중의 정확한 C/N율은 미생물이 이용할 수 있는 탄소와 비로서 결정하여야 하기 때문에 본 시험에서는 일반적으로 C/N율을 결정하기 위하여 사용하는 Kjeldahl방법과 아질산과 질산도 동시에 분석되는 질소 분석방법인 Forster 방법으로 병행하여 질소 함량을 분석하고 이들 함량으로 부터 얻어진 퇴비 중의 ,C/N율 변화를 조사하였으며 그 결과는 다음과 같다. 1. 퇴비화 기간에 따라 두 질소 분석 방법에서 얻어진 C/N율이 모두 점차 감소하였으며 퇴비화 초기 2주까지 급격히 감소한 후 2주와 6주사이에 약간 증가 내지 일정하게 유지하다가 이후부터 완만하게 감소하는 경향이었다. 2. 퇴비화 기간에 따라 두 질소 분석 방법에서 분석된 퇴비 종류의 질소와 탄소로부터 얻어진 모든 C/N율을 비교할 때 Kjeldahl 방법에 의한 C/N율이 Fo¨rster 방법에 의한 C/N율 보다 높았다. 3. 통상 퇴비 중 C/N율 계산을 위하여 질소 분석 방법으로 사용하는 Kjeldahl 방법에서 얻은 총 질소와 총 탄소로 부터 얻어진 C/N율이 Fo¨rster방법에 의한 미생물이 이용할 수 있는 질소와 미생물이 이용할 수 있는 탄소로 부터 얻어진 C/N율보다 C/N율로서 5백분율로 36% 높았다. 4. 총 찬소와 Kjeldahl 방법에 의한 총 질소 간의 C/N율, 미생물이 이용할 수 있는 탄소와 Kjeldahl 방법에 의한 미생물이 이용할 수 있는 질소간의 C/N율, 총 탄소와 Fo¨rster 방법에 의한 총 질소간의 C/N율 및 미생물이 이용할 수 있는 탄소와 Fo¨rster 방법에 의한 미생물이 이용할 수 있는 질소간의 C/N율간에 서로 서로 고도의 유의적인 정(+)의 상관이 있었다. To determine the accurate C/N ratio of compost, biodegradable carbon and nitrogen in compost must be analyzed. In biodegradable nitrogen analyzed by Kjeldahl Method, nitrate and nitrite which are available for microbes can not be detected at all. By means of Fo¨rster Method, nitrate and nitrite can be detected. Therefore, various nitrogens in compost were analyzed by Kjeldahl and Fo¨rster Method to investigate the seasonal changes of various C/N ratios of compost. C/N ratios in compost analyzed by Kjeldahl and Fo¨rster Method were decreased rapidly within 2 weeks after composting, then were not changed to 6 weeks, and thereafter were decreased slowly with the lapse of composting time. C/N ratios analysed by Kjeldahl Method were higher than those analyzed by Fo¨rster Method. C/N ratios of total carbon/total nitrogen analyzed by Kjeldahl Method were higher(5 as C/N ratio or 36% ) than those of biodegradable carbon/biodegradable nitrogen analyzed by Fo¨rster Method. Highly positive correlations were observed among C/N ratios of total carbon/total nitrogen analyzed by Kjeldahl Method total carbon/total nitrogen analyzed by Fo¨rster Method and biodegradable carbon/biodegradable nitrogen analyzed by Fo¨rster Method one another.
Strain Sensor with Self-healing Ability Using a Dry-Resistant Hydrogel-Based Conductive Composite
서정윤,이화성 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
Self-healing hydrogels have attracted great attention for applications as electronic skin and flexible strain sensors due to their excellent flexibility and strain-sensitivity. In particular, poly(vinyl alcohol) (PVA)-based hydrogels are widely used for devices that require self-healing ability. However, PVA-based hydrogels are made based on water, so the moisture evaporates easily and cannot be used for a long time. Here, 1,2,3,4-butanetetracarboxylic acid (BTCA) and sodium(polyacrylate) were added to the PVA-based hydrogel to increase drying resistance. Dry resistance (Wt/Wt = 0) was measured by weighing hydrogels while storing them at 25 and 40 ℃. As BTCA and SPA were added, the drying resistance changed from 0.88 to 0.95 at room temperature and from 0.33 to 0.77 at 40 ℃ Then, the hydrogel was given conductivity by adding CNT and the strain sensor was able to detect various human motions.
Strain Sensor with Self-healing Ability Using a Dry-resistant Hydrogel-based Conductive Composite
서정윤,이화성 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Poly(vinyl alcohol) (PVA) based hydrogel is widely used in devices requiring self-healing abilities. However, agarose/PVA-based hydrogels are made based on water, so moisture evaporates easily and has the disadvantage that it cannot be used for a long time. In this study, 1,2,3,4-butane tetracarboxylic acid (BTCA) and sodium (polyacrylate) (SPA) were added to a PVA-based hydrogel to increase drying resistance. Drying resistance was measured by measuring the weight of the hydrogel while storing the hydrogel at 25 °C and 40 ℃ for 24 hours. As a result, the drying resistance (W<sub>t</sub>/W<sub>t</sub> = 0) of the agarose/PVA-based hydrogel using water as a single solvent changed from 0.84 at 25 °C to 0.34 at 40 °C. However, Hydrogels added with BTCA and SPA changed to 0.95 at 25 °C and 0.69 and 0.73 at 40 °C, respectively. Then, CNT was added to the produced hydrogel to give conductivity, and it was applied as a strain sensor based on the stretchability and self-healing ability of the hydrogel.