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        검색결과 6

        2.
        2013.06 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        This field study was performed to investigate indoor concentrations of 22 odorous compounds, which are regulated by the domestic act, emitted from poultry buildings through on-site visit per month from July, 2011 to June, 2012. Of 22 odorous compounds, the highest concentration was found in ammonia with ppm unit, followed by hydrogen sulfide, methyl ethyl ketone, propionic acid and butylic acid with ppb unit of approximate hundred level. The other odorous compounds were detected below ppb unit of approximate ten level. A remarkable finding is that there is no poultry building which showed the airborne levels of five aldehyde- based odorous compounds (acetaldehyde, propionaldehyde, butyraldehyde, n-valeraldehyde and i-valeraldehyde). Generally there was no consistent concentration distribution of odorous compounds between poultry building applied with forced ventilation and poultry building applied with natural ventilation. It was found, however, that there was considerable concentration difference among odorous compounds. In temporal distribution of odorous compounds, their concentrations in summer season (June to August) when ventilation rate in poultry building decreased relatively were generally higher than those in winter season (December to February) when ventilation rate in poultry building is relatively high. The seasons of spring (March to May) and autumn (September to November) showed middle levels of odorous compounds between summer and winter. The limit of this study is that unexpected conditions such as clearance of poultry building, poultry shipment and disorder of air pump were not controlled intentionally on the on-site investigation days.
        4,600원
        3.
        2001.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        1980년대 말 시점과 1990년대 말 시점을 비교구간으로 설정하여 서울 한남동지역에 대한 대기중 수은의 농도분포변화양상을 비교해 보았다. 긴 시간 동안 발생원과 소멸원이 지닌 관계의 변화와 같은 영향에 의해, 양 기간대의 농도분포는 절대적 및 상대적 관점에서 모두 뚜렷한 차이를 보여 주었다. 80년대말 시점의 농도가 14.4±9.56 ngm-3인데 반해, 90년대 말 시점에는 이보다 1/3 가까이 감소한 5.34±3.92ngm-3를 유지하였다. 두 기간대에 관측된 농도 및 주변환경변수를 여러 가지 주기별로 수은의 농도분포양상을 비교해 보았다. 24시간 주기 또는 계절별로도 양기간대의 농도분포는 뚜렷한 차이를 보여 주었다. 과거 시점에는 낮 시간대에 고농도가 발생하는 현상이 빈번한데 반해, 현 시점에서는 이러한 양상을 확인하기가 어려웠다. 또한 계절적으로 겨울철에 고농도가 집중되는 현상은 과거나 현재나 유사하지만, 과거의 경우 겨울철 고농도가 여타 계절에 비해 확연했던데 반해, 최근의 분석결과는 계절간 차이가 상당 수준 줄어 들었다는 것을 보여 주었다. 이들 자료를 이용하여, 여러 가지 통계분석을 실시한 결과, 양 기간대에 현저하게 차이가 나는 농도분포는 주로 각 기간대별로 수은의 농도를 조절하는 주생성원의 성격이 현저하게 다른 데 따른 가능성이 강할 것으로 사료된다.
        4,200원
        4.
        2012.06 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 주어진 호우사상을 베타분포로 적절히 표현하기 위한 매개변수의 결정 방법을 제시하였다. 이를 위해 첨두에 대한 고려를 추가한 경우와 그렇지 않은 경우, 실제 우량주상도 및 첨두를 중심으로 재배열된 수정 우량주상도를 사용하는 경우 등을 고려하여 그 특성을 비교 검토하였다. 본 연구는 서울 지점의 2010년 독립 호우사상과 1961∼2010년 사이의 연 최대치 독립 호우사상을 대상으로 베타분포를 적용하고, 그 결과를 분석하였다. 그 결과를 정리하면 다음과 같다. 첫째, 베타분포를 이용하여 실제 호우사상의 우량주상도 형태를 유사하게 표현하기 위해서는 첨두에 대한 추가적인 고려가 필요한 것으로 확인되었다. 둘째, 첨두를 중심으로 시간강우를 좌우 순차적으로 재배열한 수정 우량주상도를 이용하는 경우가 실제 우량주상도를 이용하는 경우보다 실제 강우의 시간분포 특성에 보다 가까운 베타분포를 유도함을 확인하였다.
        5.
        2007.07 KCI 등재 서비스 종료(열람 제한)
        In order to understand the temporal distribution of pico- and nanoplankton and facters controlling its distribution at a station in Okkye Bay of Masan Bay located in the southern part of Korea, this study was conducted on two weeks interval from April 2005 to April 2006, and several abiotic and biotic factors were measured. During the study, picoplankton consisted of picoflagellates, cyanobacteria and heterotrophic bacteria, and nanoplankton consisted of nanoflagellates excluding dinoflagellates. The concentration of chlorophyll-a(chl-a) was a mean of 4.33㎍/L, and the nanoplanktonic(<20㎛) chl-a size fraction was a mean of 39.5% and significantly correlated with water temperature. The abundances of cyanobacteria and photosynthetic flagellates(PF) were means of 24.4×10³cells/mL and 2.87×10³cells/mL, respectively. The contribution of picoflagellates to the PF abundance varied among the sampling occasions and was a mean of 29%, but to the PF carbon biomass was 2.6% only. The PF abundance had significant relationships with water temperature, and silicate and TIN concentrations, suggesting that the PF abundance seemed to be primarily bottom-up regulated. The abundance of heterotrophic bacteria was a mean of 3.18×10⁶cells/mL and unlike other ecosystems it did not have relationships with chl-a and heterotrophic flagellates(HF), suggesting that bacterial abundance did not seem to be bottom-up or top-down regulated. HF mostly consisted of cells less than 5㎛ and its abundance was a mean of 2.71×10³cells/mL. Of the HF abundance, picoflagellates occupied about 31%, and occupied about 9% of the HF carbon biomass. HF grazing activity on heterotrophic bacteria was relatively low and removed about 10% of bacterial abundance, suggesting that HF might not be major consumers of bacteria and there seems to be other consumers in Okkye Bay. These results suggest that Okkye Bay may have a unique microbial ecosystem.
        6.
        2000.12 KCI 등재 서비스 종료(열람 제한)
        In this study, the distribution characteristics of volatile organic compounds (VOCs) were investigated on the seasonal basis across spring, summer, and fall during the year of 1998. According to this analysis, most VOC species investigated exhibited strong temporal trends. Over diurnal scale, there distribution characteristics were affected by seasonal factors strongly. While they showed high day/night ratio pattern during spring, the pattern was reversed during fall. When the seasonal mean values were compared between the two seasons, the spring values were systematically higher than their counterparts in most cases. In addition when our VOC measurement data were compared with those reported from elsewhere, we were able to conclude that the VOC levels in the study area are comparable to the level weakly impacted by the regional emissions of VOCs. Although our data are not sufficient enough to systematically explain the atmospheric distribution and behavior of VOCs, the findings of strong correlations among some of VOC species suggests strong need for investigating their interactions in the earth's atmosphere.