신민환 Shin Min Hwan , 신용철 Shin Yong Chul , 허성구 Heo Sung Gu , 임경재 Lim Kyoung Jae , 최중대 Choi Joong Dae

DOI: JKWST Vol.49(No.6) 3-9, 2007

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Stream flow and water quality were measured and analyzed with respect to flow-weighted mean concentrations (FWMCs) of 21 rainfall events from a forested watershed (Forest Research Watershed: FRW) and two mixed watersheds of agriculture and forest (YuPo-Ri Watershed: YPW and WolGog-ri Watershed: WGW) located in the middle of the North Han River basin. The monitoring of each watershed was one year and conducted between 2004 and 2006. YPW showed more intensive agricultural practices than WGW where traditional practices were common. The average of the 21 FWMCs were in the order of YPF>WGW>FRW and were significantly different from each other at the level of 0.05. It was shown that the land use with intensive agricultural practices produced and discharged more NPS pollutants than that with traditional practices and forest. Specially, SS concentrations from the mixed watersheds were significantly higher than those from FRW. Influencing factors on runoff were analyzed rainfall and watershed area. And rainfall intensity was greater impact on runoff than daily rainfall. Measured water quality indices were shown positive correlations among them in general. However, no significant correlation was shown between COD and nutrients(T-N and T-P).

김태철 Tai-cheol Kim , 이덕주 Duk-joo Lee , 문종필 Jong-pil Moon , 이재면 Jae-myun Lee , 구희진 Hui-jin Gu

DOI: JKWST Vol.49(No.6) 11-20, 2007

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In order to make the way to determine the instream flow more practically, we have investigated many case studies and reviewed reports and papers. To validate instream flow level suggested by the case studies, DAWAST and HEC-RAS model were applied to the Gap-stream watershed in Daejeon city. Flow-duration analysis was performed both with the stream flow data gauged in the Indong, Boksu, and Hoeduck stations, and with the stream flow data estimated by the DAWAST model and the specific discharge method. Instream flow was determined among the flow-duration analysis, DAWAST, HEC-RAS model and mass balance approach. It was satisfied with various factors such as target water quality, water depth for eco-system and resorts, water surface width, flow velocity for landscape in dry season. The study suggested that the mean low flow could be replaced into the instream flow for the preliminary study because the instream flow considering ecosystem, landscape, water-friendly environment and water quality was generally close to the mean low flow.

장민원 Jang Min-won , 유승환 Yoo Seung-hwan , 최진용 Choi Jin-yong

DOI: JKWST Vol.49(No.6) 21-33, 2007

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Different vegetation indices from satellite images have been used for monitoring drought damages, and this study aimed to develop a drought index using NOAA/AVHRR NDVI(Normalized Difference Vegetation Index) and to analyze the temporal and spatial distribution of spring drought severity in North Korea from 1998 to 2001. A new drought index, DevNDVI(Deviation of NDVI), was defined as the difference between a monthly NDVI and average monthly NDVI at the same cover area, and the DevNDVI images at all years except for 2001 demonstrated the drought-damaged areas referred from various domestic and foreign publications. The vegetation of 2001 showed high vitality despite the least amount of rainfall among the target years, and the reason was investigated that higher temperature above normal average would shift the growing stages of plants ahead. Therefore, complementary methods like plant growth models or ground survey data should be adopted in order to evaluate drought-induced plant stress using satellite-based NDVI and to make up for the distortion induced by other environments than lack of precipitation.

이형진 Lee Hyung Jin , 최원 Choi Won , 이정재 Lee Jeong Jae

DOI: JKWST Vol.49(No.6) 37-46, 2007

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In designing the structure, the stress path is the basic data. But the stress path is not standardized to analysis the structure. So the one-dimensional frame element structure model with the triangle irregular network is used to solve the problem. And the refined evolutionary structural optimization(RESO) used in structural topology optimization is applied to this study. Through this process, the search method of the stress path is advanced and the burden of the calculation. is reduced.

오경윤 Oh Kyung Yoon , 조진구 Cho Jin Goo , 최수명 Choi Soo Myung , 홍종현 Hong Chong Hyun

DOI: JKWST Vol.49(No.6) 47-54, 2007

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This paper is on the research of the special character of the dynamic response according to a design of the clamped reinforced concrete slab. In this study, the 20-node solid element has been used to analyze the dynamic characteristics of RC slabs with clamped edges. The elasto-visco plastic model for material non-linearity and the smeared crack model have been adopted in the finite element formulation. The design factor, which affect the dynamic response of the reinforced concrete slab, are the steel layer thickness, steel layer depth, steel layout method, steel layout angle and the slab thickness and span ratio. The main purpose of this study was to find out the dynamic response of the reinforced concrete slab according to above variables. The reduction of deflection/thickness ratio appeared less than 2% when the slab thickness between 20 and 21cm. It is desirable that the slab thickness must be above 20-21cm. The reduction ratio of deflection is appeared greatly when the value of the span/thickness ratio is between 25 and 30. In conclusion, the steel layer depth and thickness had a little effect on deflection of the dynamic response, but had no effect on the steel layout angle.

남상운 Nam Sang-woon , 김대식 Kim Dae-sik

DOI: JKWST Vol.49(No.6) 55-62, 2007

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Actual states of energy utilizations were investigated and analyzed on three representative rural villages in Chungcheongnam-Do. Rural residents were almost using the ondol boiler as a heating facility and oil(diesel, kerosene) and electricity(night thermal-storage power service) as a heating energy. There were a few households using briquette or firewood in a fuel hole with Korean hypocaust. Most of their cooking facilities were gas ranges using LPG. The most popular hot-water supply system was an oil boiler and the next was an electricity boiler. The amount of energy use in a rural household generally showed 20,000 to 40,000 won/month of the electric power rate, 400 to 800 liter/year of the oil and 60 to 120 kg/year of the LPG. Prompt measures should be taken to promote the spread of new and renewable energy such as solar heat, biomass and wind power, etc.

오윤경 Oh Yun-gyeong , 최진용 Choi Jin-yong , 배승종 Bae Seung-jong , 장민원 Jang Min-won

DOI: JKWST Vol.49(No.6) 65-76, 2007

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Studies in landscape ecology have emphasized on the relationship between landscape patterns and shapes. A variety of landscape metrics has been developed so far to quantify landscape structures. Therefore, their developments and widespread applications become possible with the advent of spatial information systems including geographic information systems(GIS) and remote sensing. This study is to grasp the change of land use and landscape ecology indices, and to analyze the change of landscape structure in a part of Gyeonggi-do during 15 years from 1985 to 2000. Green-area distribution maps and agricultural-area distribution maps for the analysis were reconstructed from land cover maps constructed by WAMIS(Water Management Information System). And then, 4 landscape ecology indices(TA, LPI, SHAPE_AM, CAI_MN) for the green-area and 5 landscape ecology indices(TA, PD, LPI, LSI, CAI_MN) for the agricultural-area were selected by using pearson correlation analysis. According to the spatio-temporal change analysis using landscape ecology indices, the green-area fragmentation of Yongin was the most severe of the study area and the agricultural-area fragmentation of Gwangju and Namyangju was more severe than any other regions.

김대식 Kim Dae-sik , 최현성 Choi Hyun-sung

DOI: JKWST Vol.49(No.6) 77-84, 2007

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This study aims to analyze temporal variation of rural tourist potential in village level. In order to analyze the temporal variation, this study applied a green-tourism potential evaluation model(GPEM) to a study area, Namil-myun with 18 villages, which located on county of Kumsan, province of Chungnam. GPEM consists of two factors about human resources, which is quantified by resident population of the village who will be participated in village management for green-tourism, and amenity resources, which is calculated by an evaluation table with 31 criteria and their weighting values. Data surveying for the study area was performed at August 2003 and 2006, respectively, in order to quantity the 31 evaluation criteria of GPEM. From the analysis results, the amenity resources with three sub-classes of industrial, natural, and social resources showed that the evaluation values of 2006 were increased in more than those of 2003, displaying the increase rate of ranging from 108% to 112% in the three sub-classes, except of one village in social resources and three village in natural resources with reduction. In human resources, the evaluation values of 2006 were highly increased more than those of 2003, showing the rate of 556% in the gradient of linear regression line. In green tourism potential in each village, the evaluation results for two time series showed that the potential is increased by time, which the increase rate of the potential is 114%. Ultimately, the results of this study enable us to realize that the green-tourism potential in each village over time is increased, for example, due to developing new facilities in the village by investment of government and participating in rural tourism by resident people over time. From the analysis and results, the methodology of this study can be applied to analyze the temporal variation of the potential for villages having investment from government.

조중기 Cho Joong-ki , 장병욱 Chang Pyeong-wook , 김성필 Kim Seong-pil , 허준 Heo Jun

DOI: JKWST Vol.49(No.6) 87-92, 2007

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Strain-stress behavior of soil is of importance in dealing with geo-techniques which relate to bearing capacity, slope stability, earth pressure and many geo-technical problems. So understanding mechanism of the behavior and reinforcing soil to the required state has been an issue for many years. This paper presents the possibility of magnetic force in enhancing shear strength. To analyze the reinforcing effect, triaxial compression tests were performed on two sets of steel-sand mixtures, one of which is influenced by permanent magnet, NdFeB. With magnetic force under 50 kPa confining pressure, maximum shear strengths increased according to steel percentages but under 100 kPa, no significant changes in maximum shear strengths occurred. Therefore the analysis by Mohr's circles indicates that magnetic force converts the shearing characteristics of sand into those of clay.

김성필 Kim Seong-pil , 손영환 Son Young-hwan , 장병욱 Chang Pyung-wook

DOI: JKWST Vol.49(No.6) 93-101, 2007

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In general, geotechnical properties have many uncertain aspects, thus probabilistic analysis have been used to consider these aspects. It is, however, quite difficult to select an appropriate target probability for a certain structure or construction process. In this study, minimum expected cost design method based on probabilistic analysis is suggested for design of vertical drains generally used to accelerate consolidation in soft clayey soils. A sensitivity analysis is performed to select the most important uncertain parameters for the design of vertical drains. Monte Carlo simulation is used in sensitivity analysis and probabilistic analysis. Total expected cost, defined as the sum of initial cost and expected additive cost, varies widely with variation of input parameters used in design of vertical drain systems. And probability of failure to get the minimum total expected cost varies under the different design conditions. A minimum value of total expected cost is suggested as a design value in this study. The proposed design concept is applicable to unit construction process because this approach is to consider the uncertainties using probabilistic analysis and uncertainties of geotechnical properties.

박근애 Geun-ae Park , 김성준 Seong-joon Kim

DOI: JKWST Vol.49(No.6) 105-114, 2007

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This study is to predict the spatial expansion of urban areas by applying CA (Cellular Automata)-Markov technique considering MCE (multi-criteria evaluation) and MOLA (multi-objective land allocation) of factor analysis. For the 10 administration districts (3677.3 ㎢) including the whole Anseong-cheon watershed, the past six temporal land use data (1973, 1981, 1985, 1990, 1994, 2000) from Landsat satellite images were prepared. During this period, the urban area increased 233.71 ㎢. Using the 36 indices composed of topological characteristics, population and land use change, the final factor map of MOLA was produced through 5 maps of MCE. Using 1990 and 1994 land use data, the 2000 predicted urban area of CA-Markov with factor map showed 0.06 % improvement of absolute error comparing with that of CA-Markov without factor map. By the CA-Markov technique considering factor map, the 2030 and 2060 urban area increased 58.94 ㎢ (0.78 %) and 60.14 ㎢ (0.81 %) respectively comparing with 2000 urban area (313.19 ㎢). The 2030 and 2060 paddy area decreased 93.28 ㎢ (2.54 %) and 93.65 ㎢ (2.55 %) respectively comparing with 2000 paddy area (1383.23 ㎢).