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        검색결과 6

        2.
        2011.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        구조모델의 하나인 Maxwell-Eucken(ME) 모델을 이용하여 불포화 다공성 매질의 유효열전도도를 예측할 수 있는 새로운 모델을 제시하였다. 제시된 모델은 기질, 물 그리고 공기가 각각 연속상으로 존재하는 경우에 해당하는 3개 ME모델의 선형조합으로 표현되며, 매질 내에서 각 성분의 상대적 연속성 정도를 나타내는 '연속성계수'의 개념을 도입하여 선형방정식의 계수로 이용하였다. 기질의 연속성계수는 공극률과 선형의 관계를, 물과 공기의 연속성계수는 포화도와 선형 또는 비선형의 관계를 갖는 것으로 가정하였다. 공극구조가 알려진 3개 시료에 대한 열전달 모사 결과와 3개 시료의 열전도도 실험 결과를 이용하여 제시된 모델의 신뢰성을 평가하였다. 6개 시료에 대한 모델 예측값의 결정계수(R2)는 선형모델의 경우 0.86-0.98, 비선형모델의 경우 0.88-0.99로 나타나 모델의 예측 신뢰도가 매우 높은 것으로 분석되었다. 또한, 6개 시료에 대한 분석 결과를 이용하여 기질의 연속성계수와 공극률과의 관계식을 제시하였다. 따라서 본 예측모델은 기질의 열전도도, 공극률 및 포화도로부터 불포화 다공성 매질의 유효열전도도를 계산하는 데 이용될 수 있다.
        4,200원
        4.
        2008.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The density characteristics of aldehydes in Kumi electronic Industrial Complex are measured in the summer and autumn in this study. Considering the characteristics of Kumi, five representative monitoring sites in Kumi are selected. According to fair Korean odor method, samples are collected and analyzed from July 26th, 2005 to October, 10th. Investigation objects include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, iso-valeraldehyde, n-valeraldehyde. 40 samples in summer and 45 samples in autumn are measured and analyzed, respectively. The results show that the mean concentrations in residential area and industrial area are both obey the below sequence: acetaldehyde>formaldehyde>propionaldehyde>butyraldehyde>iso-valeraldehyde>n-valeraldehyde. For acetaldehyde, its monitored concentration in industrial areas and residential areas close to industrial areas is higher than other areas. However, for formaldehyde, its concentration in the residential area 3 in tends to be higher than that in industrial areas. Based on seasons, concentrations in summer with long sunshine duration are higher than those in autumn. It can be seen that the density distribution of aldehyde in Kumi industrial complexes is closely related with the widely use of alcohol-type additives for automobiles and alcohol-type fuels. Meanwhile, most of the researches on aldehyde concentrate on capital areas or petrochemical industrial areas, taking the chance of odor prevention and control law implementing, the management scheme and reduction strategies on aldehyde ought to be carried out, which are also suitable to the enterprise characteristics in other industrial areas of this study.
        4,000원
        5.
        2015.04 KCI 등재 서비스 종료(열람 제한)
        Groundwater level hydrographs from observation wells in Jeju island clearly illustrate distinctive features of recharge showing the time-delaying and dispersive process, mainly affected by the thickness and hydrogeologic properties of the unsaturated zone. Most groundwater flow models have limitations on delineating temporal variation of recharge, although it is a major component of the groundwater flow system. Recently, a convolution model was suggested as a mathematical technique to generate time series of recharge that incorporated the time-delaying and dispersive process. A groundwater flow model was developed to simulate transient groundwater level fluctuations in Pyoseon area of Jeju island. The model used the convolution technique to simulate temporal variations of groundwater levels. By making a series of trial-and-error adjustments, transient model calibration was conducted for various input parameters of both the groundwater flow model and the convolution model. The calibrated model could simulate water level fluctuations closely coinciding with measurements from 8 observation wells in the model area. Consequently, it is expected that, in transient groundwater flow models, the convolution technique can be effectively used to generate a time series of recharge.
        6.
        2014.04 KCI 등재 서비스 종료(열람 제한)
        Temporal variation of groundwater levels in Jeju Island reveals time-delaying and dispersive process of recharge, mainly caused by the hydrogeological feature that thickness of the unsaturated zone is highly variable. Most groundwater flow models have limitations on delineating temporal variation of recharge, although it is a major component of the groundwater flow system. A new mathematical model was developed to generate time series of recharge from precipitation data. The model uses a convolution technique to simulate the time-delaying and dispersive process of recharge. The vertical velocity and the dispersivity are two parameters determining the time series of recharge for a given thickness of the unsaturated zone. The model determines two parameters by correlating the generated recharge time series with measured groundwater levels. The model was applied to observation wells of Jeju Island, and revealed distinctive variations of recharge depending on location of wells. The suggested model demonstrated capability of the convolution method in dealing with recharge undergoing the time-delaying and dispersive process. Therefore, it can be used in many groundwater flow models for generating a time series of recharge.