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        검색결과 28

        22.
        2000.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        실리콘 고무(고무상고분자)와 폴리스틸렌(유리상고분자)을 이용하여 true-IPN을 합성하였다. 합성방법은 단계(sequential) IPN(interpenetrating polymer net- work) 제조방법이며, 이때 IPN 내의 폴리스틸렌 함량을 10-70 wt%로 변화시켜 폴리스틸렌의 함량에 따른 산소/질소의 투과특성을 조사하였다. FTIR과 NMR의 결과 단계IPN 합성법으로 실리콘고무-폴리스틸렌의 IPN분리막이 제조되었음을 확인하였으며, 열분석 결과 폴리스틸렌의 함량이 증가할수록 실리콘고무와 폴리스틸렌의 혼합도(degree of mixing)가 증가한다는 것을 알 수 있었다. 기체투과특성 조사에서는 폴리스틸렌의 함량이 증가할수록 산소투과도는 감소하는 경향이 있었으나, 50wt% 폴리스틸렌이 함유된 분리막에서 일시적인 증가를 보여주었다. 또한 선택도는 폴리스틸렌의 함량이 증가하면서 약간 증가하다, 50wt% 폴리스틸렌이 함유된 분리막에서 20.6% 향상된 최대 값을 얻을 수 있었다. 이것은 폴리스틸렌이 50wt%인 분리막에서 IPN의 상호보완적인 성질이 가장 잘 나타난 결과라고 할 수 있다
        4,000원
        23.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        연속배양방식으로 서낙동강 저서층의 영양염 용출 및 이에 미치는 환경요인의 영향을 분석하였다. 희석율 감소는 배양기 수층의 영양염 농축을 초래하여 저서층에서 용출되는 N과 P의 용출율을 저하시켰으며, NH4 +와 PO4 3-의 용출은 저산소 조건에서 촉진되었다. 미생물의 활성을 저해하는 저온과 중금속은 NH4 +와 PO4 3-의 용출에는 큰 영향을 미치지 않았지만 NO3 -의 농도에 많은 영향을 미쳐 NH4 +와 PO4 3-의 용출은 무생물학적 요인에 의해서도 많은 영향을 받지만 NO3 -는 질화세균에 의한 용출 NH4 +의 산화로 대부분 생성됨을 알 수 있었다. 낮은 희석율과 용존산소 조건에서 측정한 서낙동강 저서층의 NH4 +와 PO4 3-의 용출율은 각각 평균 20.4 mg-N m-2 day-1, 8.1 mg-P m-2 day-1로, 서낙동강의 평균 수면적과 저수량 및 체류시간을 고려하면 저서층의 영양염 용출이 서낙동강 수층의 NH4 +와 PO4 3- 농도의 6.6~39.8, 63.0~100%에 해당하여 서낙동강의 부영양 화에 상당한 영향을 미치는 것으로 추정된다.
        4,000원
        24.
        2017.06 서비스 종료(열람 제한)
        Despite the expectation that small green spaces provide high cooling effects, making air temperatures drop such effect in urban areas has been less explored in comparison to larger parks and urban forests. These knowledge gap has required advanced techniques to record spatial and temporal data and analysis small green spaces cooling effects. A temperature-sensing unit with ventilated double cylinder shelter (TVC) meets the needs and is known as an advanced device to record temperature data more accurately using a T-type thermocouple with a ventilator. This device also can be useful to develop guidance to describe thermal environment with a finer scale and an experimental research design for identifying air temperature data with spatial analysis using TVC. However, how we would conduct transect survey with this device and make a thermal map based on the collected data is not well known. The purpose of the study was to find out the usage of TVCs in collecting air temperature data and was to produce a thermal map of the study site and analyze temperature mitigation effect of each green space. The processes to create a thermal map required complicating, endeavoring and time-consuming works as well as skills to use computer programs for space drawing and spatial analysis. The overview of all the processed to get a thermal map should be helpful for researchers and students. Collected air temperature data and recorded time of them were downloaded, converted to Excel file (XLS) and ready to be analyzed through ArcGIS 9. In the mean time, recorded transect routes were drawn on the site map as polylines and made into spatial points through AutoCAD 2007. The routes consisted of five routes classified into the lawn, the rain garden, the residence, the prairie, and the forest. Separately, each route was drawn because it should reflect its spatial and temporal specification as for when the measurement was conducted. The spatial points of each route created by AutoCAD were converted to shape files (*.shp) and added fields of air temperature and time data in their attribute tables through ArcGIS. This work was done in each measurement hour and day. To create a thermal map, were shape files of each measurement time and the boundary of the site required. IDW (Inverse Distance Weighted) in ArcGIS was analyzed for each measurement hour (10h, 13h, 16h and 19h (20h)). In each analysis, the spatial points of measured air temperature were calculated to get an isotherm distribution for the measurement hour which we call a thermal map. The thermal maps show the air temperature distribution at 10h, 13h, 16h, and 20h. They also can show how land covers have an impact on the change of air temperature on their point and the surrounding areas. The air temperature of the prairie raises up in the morning (21℃) and continues to be cool during the day and after sunset. Meanwhile, the lawn starts at lower air temperature and goes to hotter. The residence is kept lower in its air temperature by big trees. The rain garden and the forest seem to have more time to discuss on why they are not sure their cooling effects.
        25.
        2017.06 서비스 종료(열람 제한)
        Research to reduce urban temperatures and mitigate the Urban Heat Island (UHI) effect has focused primarily on the role of large urban green spaces as cool islands (Oke, 2004;Park et al., 2017). However, the role of small green spaces (SGs) such as street trees and pocket parks has not been fully investigated. The purpose of this research is to assess the mitigating effect of SGs on micro-UHI through a comparative analysis of air temperatures of SGs and non-green spaces (NGs), that include building-shaded spaces (BS) and non-shaded, impervious, paved spaces (PS) completely exposed to sunlight. Six urban blocks were the study site and in a highly developed area, Jongnogu and Junggu, Seoul, 37°34′N 126°58′E, South Korea and also located in the same micro-climatic zone. They had SGs which were vegetation patches presented as distinct areas of tree cover. And they were mapped through aerial images analysis and field survey. The experiment was conducted across six urban blocks in a highly developed area in Seoul, South Korea during daytime in summer. Two researchers at each block simultaneously recorded air temperatures at 1.5 m above the ground level using mobile loggers at one-minute intervals for an hour. Measurements were repeated three times, and 1,296 temperature readings were collected in total and made 174 mean temperature data. ArcGIS was used to perform solar radiation analysis to highlight SGs, BSs, and PSs on a thermal map. The highest air temperatures and the lowest air temperatures of each block were extracted and classified. ANOVA and Kruskal-Wallis H test utilizing SPSS statistics were used to verify the significant differences in mean air temperatures between SGs (TSG), PSs (TPS), and BSs (TBS). As a result, ΔTPS-B (the thermal effect of PSs on a block‘s air temperature) ranged from –1.38 ℃ to 2.28 ℃ with fifty-six points, ΔTBS-B (the thermal effect of BSs on a block’s air temperature) ranged from –2.38 ℃ to 2.38 ℃ with fifty-eight points and ΔTSG-B (the thermal effect of SGs on a block’s air temperature) ranged from –1.98 ℃ to 1.62 ℃ with sixty points. 68% (N = 41) of SGs were a negative number of ΔTSG-B while 50% of BSs shows a negative number. The result means that SGs contribute to reducing microscopic UHI than BSs which have much more shade area than SGs have. The results showed that SGs contributed to significantly reducing TBi up to 2.9 ℃ while BS reduced TBi up to 2.7 ℃. The highest TBi was on a PS. The air temperature difference between SGs and NGs over all the blocks ranged from 0.9 ℃ to 2.9 ℃. The air temperature difference between PS and SG was significant and ranged from 0.2 ℃ to 2.0 ℃, while the difference between BS and SG was significant and ranged from 0.1 ℃ to 1.2 ℃.
        26.
        2017.06 서비스 종료(열람 제한)
        Urban green spaces can mitigate negative impacts of urban heat island effect by creating cooling buffer zones. These cooling areas improve micro-climatic conditions and human health. Green space is important to reducing urban air temperature maxima and variation. Thus, there is an expectation that small green spaces (SGs) provide high cooling effects and thus make air temperatures drop. Meanwhile, such an effect in urban areas has been under-explored and needs more detailed spatial and temporal data. The purpose of the study was to develop a measurement method to detect temperature of various SGs with TVC and find the effect of TVC on accuracy of measured air temperature data in comparison with other non ventilation devices. We updated the cad file of the study site through comparing it with Google Map and conducting field surveys on the site. Transect survey was required to build a measurement route. We toured the study site by walk repeatedly to get the optimistic route which would have enough data points. One of considered routes which were inside of the forest and could make us get significantly influencing data was not founded for no trails so excluded in our study. After the field survey, we observed the study routes through a digital camcorder (Gopro) and recorded them on the cad file of the site because these data points should include air temperature and time data in their attribute table. As for transect survey, a researcher walked through the defined routes and collected air temperature data with two TVCs every second and two Testo loggers covered by aluminum foil every minute at the height of 1.5m from the ground. Stationary survey was conducted with two TVCs in every second data collection and two Testo loggers covered by aluminum foil in every minute data collection on the resting area at the entrance of the site. One of TVCs and one of Testo loggers were set at the height of 0.5m while the others of TVCs and Testo loggers were at the height of 1.5m. On the stationary point, other microclimate variables such as wind velocity, wind direction and solar irradiance were also measured and recorded every minute. We repeated the measurement for one day or two days a month (November, 2016 ~ May, 2017) and four times a day. The measuring days were selected when they were clean and calm. As a result, air temperature from TVCs was entirely lower than that from Testo loggers on the stationary survey. This trend was shown during the day rather than after sunset. The difference of air temperature from between TVCs and Testo loggers ranged from 2 ℃ after sunset to 5 ℃ at 16h. At the height of 0.5m, a Testo logger's data showed much higher than a TVC's data. These results show that Testo loggers tend to be easily influenced by the change of solar radiation. Moreover, there was the ventilation effect at the stationary. So no ventilation could be the main reason why Testo loggers' data were high. However, TVCs' lower temperature explains how effectively these devices block the solar radiation and ventilate air inside the cylinder.
        27.
        2016.10 KCI 등재 서비스 종료(열람 제한)
        Little attention has been paid to the functional aspect of the flower petal of Paeonia lactiflora, compared to that of its root. To determine the components of flower petal of Paeonia lactiflora, we conducted the Fourier transform ion cyclotron resonance (FT-ICR) MASS spectrophotometric analysis. We detected the 24 different types of ingredients from the 70% ethanol extracts of flower petal of peonia lactiflora cv. ‘Red Charm’. The main compounds were quercetin glucopyranosides, methyl gallate, paonioflolol and kaemperol glucopyranosides. We further tested its functional activity. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of the extracts was 87.9-90.4% at 0.1mg/ml. This result showed that these flower extracts have approximately 5-fold stronger antioxidant potential than a previous report with root extracts (Bang et al. 1999). The result of tyrosinase inhibition assay of Paeonia lactflora extract was almost similar to that of arbutin except significantly higher effect in the coral sunset extract at 0.1% concentration. Hyaluronidase inhibition assay showed 76.5% inhibition at 5% concentration of this flower extract, indicating that Peaonia lactiflora flower extracts have the major anti-inflammatory, anti-oxidant and brightening effects. Taken together, these results suggest these three Paeonia lactiflora species extracts might provide the basis to develop a new natural brightening agent.
        28.
        2012.02 서비스 종료(열람 제한)
        구조물과 지반상호간의 동적 특성을 보다 신뢰성 있게 분석하여 지진재해로부터 구조물을 효과적으로 보호하기 위해 지반의 증폭특성은 반드시 고려되어야 하는 요소이다. 지반증폭 특성을 분석할 때 여러 가지 방법이 제시되어 있으나 본 연구에서는 Nakamura(1989)에 의해 제시된 방법을 적용하였다. 본 방법은 얕은 지반의 상시미동의 표면파 특성을 이해하기 위해 제시되었으나. 최근 S파 및 Coda파 등에 적용되어 지반의 동적인 증폭 특성연구에 많이 이용되고 있어 본 연구에서 S파 에너지에 적용하였다. 2005년 3월 20일 발생한 후쿠오카 본진을 포함하여 규모 3.0이상의 모두 12개 중규모의 후속 지진으로부터 국내 관측소에 관측된 255 여개의 지반진동 자료를 분석하였다. 이를 이용하여 8개 주요 국내 지진관측소 지반의 동적인 증폭특성을 분석하였다. 각각의 지진관측소마다 저진동수, 고진동수 특성, 관측소 고유의 우월진동수기 서로 상이하여 관측소 고유의 증폭특성을 보여주었다. 본 연구의 결과를 다른 분석방법을 적용하여 얻어진 결과와 비교하면 국내 지반의 동적 특성 및 지반분류 연구에 많은 정보를 줄 수 있다.
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