김선주 Sun Joo Kim , 이주용 Joo Yong Lee , 김필식 Phil Shik Kim

DOI: JKWST Vol.47(No.2) 3-12, 2005

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The objective of this study is securement of upland irrigation water using storage level management of small dams. However, it is not new development of water resources but securement of water using storage level management of existing dam. This study has enhanced the water utilization coefficient of dam, after extra available water had been calculated by application of periodical management storage level and this water is used to other water like the upland irrigation water demand. As the result of application, it can secure extra available water except the water requirement. Minimum extra available water except flood is about 20,000,000㎥ and crop irrigation water demand of 10yr frequency is about 2,033,000㎥ in Seongju. The utilization of crop irrigation water can be possible. And extra available water is about 3,102,000㎥ in 2000, 1,959,000㎥ in 2001 except flood period and crop irrigation water demand of 10yr frequency is about 2,270,000㎥ in Donghwa. It is judged that extra available water cannot be used to crop irrigation water during the dry season in Dongwha. Consequently, when management storage level is determined and more efficient use of water is gotten like this study, water utilization coefficient will be enhanced.

박근애 Park Geun Ae , 이미선 Lee Mi Seon , 김현준 Kim Hyeon Jun , 김성준 Kim Seong Joon

DOI: JKWST Vol.47(No.2) 15-21, 2005

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This study is to trace the change of stream shape using the past series of aerial photographs, and to compare the land use changes of riparian area along the stream. For the Gyeongan national stream, aerial photographs of 1966, 1981 and 2000 were selected and ortho-photographs were made with interior orientation and exterior orientation, respectively. Apparent changes of the stream were found that the consolidated reaches of stream by levee construction became straight together with widening of their stream widths. Especially the stream width of inlet part of Paldang lake widened almost twice because of the rise of water level by dam construction in 1974. The land use of riparian areas of three selected years were classified into six categories (water, forest, agricultural land, urban area, road, sandbar) by digitizing method. The forest and agricultural lands decreased and urban area increased as the stream maintenance had been performed.

나준엽 Na Joon Yeup , 정남수 Jung Nam Su , 이정재 Lee Jeong Jae

DOI: JKWST Vol.47(No.2) 25-32, 2005

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In evaluation of public works, its components related with benefit and cost in feasibility analysis can be classified to quantative and qualitative elements, To evaluate qualitative components which can not be calcu-lated by numerical value, several methods are used to assess relative importance. AHP (Analytic Hierarchy Process) is representative method which can evaluate importance, but it has difficulties in organization of expert group, execution of question, and subjective decision of questioner. Information measure technique can be used to evaluate these qualitative importance of environmental and social components in public works planning. In result of comparing importances of AHP and information measure technique, it has statistical significance in of road project.

서교 Kyo Suh , 이정재 Jeong Jae Lee

DOI: JKWST Vol.47(No.2) 35-44, 2005

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While the need for analyzing and interpreting agricultural logistics are becoming more and more prominent with the rapid changes within the agricultural environment, previously mathematical models have been proved to have its limitations due to the unpredictable traits of agriculture itself and finding the adequate simulation model is not easy. Therefore, in this research, the tank model that has been used to analyze the rainfall-runoff in watersheds, was used to develop a logistics model for estimating shipment by agricultural production. The model was certified by wholesale market data of garlic.

홍성구 Hong Seonggu

DOI: JKWST Vol.47(No.2) 45-52, 2005

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Biomass is one of the most competitive renewable energy resource and can be used for heating for rural applications. A economic assessment was made of biomass heating, using the tool BIOH2000 from RETScreen^® International Clean Energy Decision Support Centre. For a 260kW heating system for 50 farm houses, the assessment showed a very promising results. Internal rate of return was 19.7% and year-to-positive cash flow was 5.1 years. Relative price of biomass over fossil fuel significantly affected the economic feasibility of the project. Heating demand was directly related to annual demand of biomass and economic feasibility. Relative cost of distribution pipe over the total initial costs also affected the economic feasibility of the project. The economic feasibility was expected to be improved by the probable greenhouse emission reduction credit and reduction of initial costs through utilizing existing heating system for peak or back up heating system.

성찬용 Sung Chan Yong , 박일순 Park Il Soon

DOI: JKWST Vol.47(No.2) 55-61, 2005

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This study was performed to evaluate fluidity of super flow concrete using recycled coarse aggregate. The unit weight was 2,246~2,344 kg/㎥, the unit weights of these concrete were decreased with increasing the content of fly ash and recycled coarse aggregate. The slump flow was 58~63㎝, the Box type passing was 3.4~6.8㎝, respectively. The L type compacting was excellent in the fly ash content 10% and 20%, but, it was showed in good in the fly ash content 30%. The super flow concretes using recycled coarse aggregate were improved by substitution in the range of less than the fly ash content 20% and recycled coarse aggregate content 75%. This recycled coarse aggregate can be used for super flow concrete.

윤준노 Youn Joon-no , 성찬용 Sung Chan-yong

DOI: JKWST Vol.47(No.2) 63-72, 2005

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In this study, the physical and mechanical properties of steel fiber reinforced lightweight polymer concrete were investigated experimentally with various steel fiber contents. All tests were performed at room temperature, and stress-strain curve and load-deflection curve were plotted up to failure. The unit weight of steel fiber reinforced lightweight polymer concrete was in the range of 1,020~1,160 kg/㎥, which was approximately 50% of that of the ordinary polymer concrete, The compressive strength, splitting tensile strength, flexural toughness and flexural load-deflection curves after maximum load were shown with increase of steel fiber content. The stress-strain curves of steel fiber reinforced lightweight polymer concrete were bilinear in nature with a small transition zone. Based on these results, steel fiber reinforced lightweight polymer concrete can be widely applied to the polymer composite products.

박찬기 Park Chan-gi , 원종필 Won Jong-pil

DOI: JKWST Vol.47(No.2) 73-84, 2005

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The main objective was to evaluate the tensile and bond properties of FRP rebar and durability performance after exposure of accelerated aging condition. Five types of FRP rebar include CFRP ISO, GFRP Asian, AFRP Technora, CFRP(D) and GFRP(D) rebars used in tensile and bond tests. Tensile test results of CFRP(D) and GFRP(D) were shown to possess acceptable tensile and durability performance compared with CFRP ISO, GFRP Asian, and AFRP Technora, Also, bond test results indicated that CFRP(D) and GFRP(D) rebars showed an ability to improve the bond strength.

이달원 Lee Dal Won , 윤현정 Yoon Hyun Jung

DOI: JKWST Vol.47(No.2) 87-96, 2005

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In this research, an attempt is made to derive the practical estimation of the degree of consolidation in soft clay from field measurements under embankments. For the practical estimation of pore water pressure in soft clay, the elasto-viscous rheological model was proposed, with a transform of parameters and a field geotechnical measurements in southern Korea. By using the rheological properties of soft clays and the dissipation of excess pore water pressure behaviour during step loading, a degree of consolidation or pore water pressure estimation in the future can be performed, and are shown to be generally close to the field measurements of pore water pressure. Finally, a pore water pressure behaviour in soft clay can be explained through measured data in field and the excess pore water pressure data can also be used to estimate settlement.

오승영 Oh Seung Young , 김진수 Kim Jin Soo , 오광영 Oh Kwang Young

DOI: JKWST Vol.47(No.2) 99-110, 2005

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Characteristics of concentrations of total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) pollutant in percolated water at four paddy field sites (Soro, Odong, Munui, and Boeun) were investigated by a nonparametric test. Percolation rate measurement and percolated water sampling were taken during irrigation periods at 5~10 day intervals. The normality of percolation rate and pollutant concentrations were examined using histogram, boxplot, and the Kolmogorov-Smirnov (K-S) test. Pollutant concentrations in percolated water showed positively skewed distribution. The median concentrations of pollutant were 1.91 mg/L for TN, 0.021 mg/L for TP, and 6.6 mg/L for COD, which were lower than its arithmetic mean concentrations by 35% for TN, 36% for TP, and 13% for COD. The median concentrations of TN and TP differed significantly among sample sites according to the Kruskal-Wallis test. However, median concentrations were not significantly different among month except for TN and TP of Soro and COD of Odong. The percolation load of pollutants during irrigation periods in the study area were estimated at 3.12~7.75 kg/ha for TN, 0.033~0.155 kg/ha for TP, and 10.7 kg/ha for COD, which were much lower than respective values reported in Japan.