Kim Seong Joon , Kwon Hyung Joong , Park Geun Ae , Lee Mi Seon

DOI: JKWST Vol.47(No.7) 3-9, 2005

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A computer system for crop information was developed using Visual Basic and ArcGIS VBA. The system is operated on ArcGIS 8.3 with Microsoft Access MDB. Landsat +ETM, KOMPSAT-1 EOC, ASTER VNIR and IKONOS panchromatic (Pan) and multi-spectral (MIS) images were included in the system to extract agricultural land use items identifiable at various spatial resolutions of images. Agriculture related data inventories using crop cover information such as texture and average pixel value of each band based on crop cultivation calendar were designed and implemented. Three IKONOS images were loaded in the system to show crop cover characteristics such as rice, pear, grape, red pepper, garlic, and surface water cover of reservoir with field surveys. GIS layers such as DEM (Digital Elevation Model), stream, road, soil, land use and administration boundary were prepared to understand the related characteristics and identify the location easily.

Park Mee Jeong , Lee Joon Gu , Lee Jeong Jae

DOI: JKWST Vol.47(No.7) 13-22, 2005

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Main purpose of this article is to classify reservoirs corresponding to their physical characteristics, for example, dam height, dam width, age, repair-works history. First of all, data set of 13,976 reservoirs was analyzed using k means and self organized maps. As a result of these analysis, lots of reservoirs have been classified into four clusters. Factors and their critical values to classify the reservoirs into four groups have been founded by generating a decision tree. The path rules to each group seem reasonable since their survivor function showed unique pattern.

Kim Young Ik , Sung Chan Yong

DOI: JKWST Vol.47(No.7) 25-33, 2005

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This study was performed to develop environment-friendly porous polymer concrete utilizing recycled aggregates [RPPC] for permeable pavement of uniform quality with high permeability and flexural strength as well as excellent freezing and thawing resistance. The void ratios of RPPC are in the range of 15~24%, showing the tendency that it is reduced to a great extent as the mixing ratio of the binder increases. The compressive and flexural strength of RPPC are in the range of 19~26 MPa and 6.2~7.4 MPa, respectively. Also, it shows a tendency to increase as the mixing ratio of the binder and filler increases. The permeability coefficients of RPPC are in the range of 6.3×10^-1~1.5×10^-2cm/s. The flexural loads of RPPC are in the range of 18~32 KN. The weight reduction ratios obtained from the test for freezing and thawing resistance are in the range of 1.1~2.4% after 300 cycles of repeated freezing and thawing of the specimen for all mixes. The relative compressive strengths of RPPC after 300 cycles of freezing and thawing against the compressive strength before freezing and thawing test are in the range of 89~96%.

Yu Chan , Yoon Chun-gyeong

DOI: JKWST Vol.47(No.7) 37-45, 2005

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In this study, R/S analysis which was proposed by Mandelbrot & Wallis (1969) was applied to evaluate the presence of the fractal property in the cone tip resistance of in-situ CPT data. Hurst exponents (H) were evaluated in the range of 0.660~0.990 and the average was 0.875. It was confirmed that a cone tip resistance data had the characteristic of fractals and it was expected that cone tip resistance data sets are well approximated by a fBm process with an Hurst exponent near 0.875. It was also observed that the boundary between layers were obviously identified as a result of R/S analysis and it will be usage in practices.

Chung Sang-ok , Park Ki-jung , E. W. Christen

DOI: JKWST Vol.47(No.7) 49-56, 2005

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Contamination in the drainage channels and creeks with pesticides used in agriculture is of a major concern in many countries. In this study the stream pesticide model RIVWQ (chemical transport model for riverine environments) was assessed for its applicability in simulating pesticide fate in drainage channels. The model was successfully calibrated against field data collected on flows and pesticide concentrations for a drainage channel from a small catchment in the Murrumbidgee Irrigation Area of southwestern New South Wales. The effects of different pesticide loading scenarios from farm fields on channel water quality were analysed by the calibrated model. The model simulated the flow rates and the pesticide concentrations in the drainage channel well. The results of the model simulation suggest that the RIVWQ model can be effectively used for predicting pesticide fate in the drainage channels and exposure assessment of pesticide in the agricultural environment.

Ji-hong Jeon , Chun G. Yoon , Kwang-wook Jung , Jae-ho Jang

DOI: JKWST Vol.47(No.7) 57-66, 2005

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The Hydrological Simulation Program - FORTRAN (HSPF) was modified to simulate nonpoint pollutant loadings from paddy fields using a field experimental data collected during 2001-2002. The concept of a “dike height” was added in a modified HSPF code, named HSPF-Paddy, to consider the function of retaining water by a weir at the field outlet. The effect of fertilization on the variances of nutrients on the soil surface and shallow soil layer was described mathematically with a Dirac delta function (or first-order kinetics). As confirmed through model verification, the HSPF-Paddy modifications were shown to represent the function of retaining water, varied ponded water, and surface runoff by forced drain during both rainy and non-rainy seasons and reasonably predicted the water balance and nutrients behavior in paddy fields. It is a distributed watershed model which, with the paddy modifications, can now simulate nonpoint pollutant loadings where paddy fields are dominant, and it can be used to evaluate the effects of paddy fields on the water quality at a basin scale, and assess the impacts of proposed BMPs applied to paddy fields.

Shin Yongchul , Heo Sunggu , Lim Kyoungjae , Choi Joongdae

DOI: JKWST Vol.47(No.7) 67-75, 2005

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It has been well-known that the Nonpoint Source (NPS) pollutions are the primary contributors to water quality degradation in the receiving water bodies as well as the Point Source (PS) pollutions. To develop an effective management practice for water quality improvement, pollutant loads must be first estimated. In many studies, the Numeric Integration (NI) method has been used because of its ease of application, irrespective of the total number of samples collected for each storm event. Thus, there have been needs for more accurate pollutant load estimation with a limited number of water quality samples. In this study, NI method and regression method using the USGS ESTIMATOR model were comparatively used to calculate the pollutant loads for the Wolgokri watershed, Gangwon Province. The NO₃-N, T-N, and T-P loads using NI method and ESTIMATOR model were 13.85 kg/ha, 45.92 kg/ha, and 1.887 kg/ha, and 11.93 kg/ha, 43.20 kg/ha, and 1.650 kg/ha, respectively. The estimated loads using ESTIMATOR model were lower than those using NI method by 86%, 94%, and 87%. These discrepancies in the estimated loads using a different load estimation method could be explained in that the total number of samples were not sufficient enough for NI method. Thus, ESTIMATOR model is recommended for the frequently stream discharge and less frequently measured water quality data.