이은정 Lee Eun Jeong , 강문성 Kang Moon Seong , 박정안 Park Jeong An , 최진영 Choi Jin Young , 박승우 Park Seung Woo

DOI: JKWST Vol.52(No.5) 1-9, 2010

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Evapotranspiration (ET) is one of the basic components of the hydrologic cycle and is essential for estimating irrigation water requirements. In this study, artificial neural network (ANN) models for reference crop evapotranspiration (ET0) estimation were developed on a monthly basis (May～October). The models were trained and tested for Suwon, Korea. Four climate factors, daily maximum temperature (Tmax), daily minimum temperature (Tmin), rainfall (R), and solar radiation (S) were used as the input parameters of the models. The target values of the models were calculated using Food and Agriculture Organization (FAO) Penman-Monteith equation. Future climate data were generated using LARS-WG (Long Ashton Research Station-Weather Generator), stochastic weather generator, based on HadCM3 (Hadley Centre Coupled Model, ver.3) A1B scenario. The evapotranspirations were 549.7 mm/yr in baseline period (1973-2008), 558.1 mm/yr in 2011-2030, 593.0 mm/yr in 2046-2065, and 641.1 mm/yr in 2080- 2099. The results showed that the ANN models achieved good performances in estimating future reference crop evapotranspiration.

이현우 Lee H. W , 심상연 Sim S. Y. , 김영식 Kim Y. S.

DOI: JKWST Vol.52(No.5) 11-17, 2010

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This study was conducted to provide design data for deciding covering method in double layers greenhouse. The variation of photosynthetic photon flux (PPF) and heat flow in air inflated and conventional double layers greenhouse was analyzed. The PPF of air inflated double covering greenhouse was less than that of conventional greenhouse during summer season because the more PPF comes into conventional greenhouse through roof vent which was rolled up for ventilation. The air inflated double layers covering greenhouse was superior to conventional type in the aspect of controlling inside temperature down owing to lower irradiation. The PPF of air inflated greenhouse was greater than that of conventional greenhouse during winter season because the transmittance of conventional greenhouse decreased by dust collected on inside plastic film nearly closed for insulation. Considering the PPF not sufficient for tomato growing in winter, the air inflated double covering system with the greater transmittance was better than conventional covering system. When the inside air of air inflated greenhouse was injected into space between the double layers of covering, the PPF of air inflated greenhouse was much less than the conventional greenhouse because the transmittance of air inflated double covering decreased due to condensation of highly humidified inside air. It was concluded that the more dried outside air should be used for inflating double layers covering. The heat insulation performance of air inflated double covering system was superior to conventional double covering system when comparing the overall heat transfer coefficients for each covering method. However the differences among the overall heat transfer coefficients depending on difference between inside and outside temperatures of greenhouse were great, it is necessary to conduct additional experiment for investigating the overall heat transfer coefficient to design the double layers covering.

김종옥 Kim Jong Ok , 박찬기 Park Chan Gi , 차상선 Cha Sang Sun

DOI: JKWST Vol.52(No.5) 19-26, 2010

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This study was conducted to find out the reasonable optimum design method of agricultural reinforced concrete structures. Selected design variables are the dimension of concrete section, reinforced steel area, and objective function is formulated by cost fuction. To test the reliability, efficiency, possibility of application and reasonability of optimum design method, both continuous optimization method and mixed-discrete optimization method were applied to the design of reinforced concrete superstructure of aqueduct and application results were discussed. It is proved that mixed-discrete optimization method is more reliable, efficient and reasonable than continuous optimization method for the optimum design of reinforced concrete agricultural structures.

전지홍 Jeon Ji-hong , 최동혁 Choi Donghyuk , 임경재 Lim Kyung Jae , 김태동 Kim Tae-dong

DOI: JKWST Vol.52(No.5) 27-35, 2010

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The characteristics of delivered nutrient loads were analyzed and the regression equations to estimate delivery ratios of nutrients (TN and TP) were developed using HSPF simulation results at six subwatersheds within the Bochung A unit watershed during 1998-2007. TN delivery ratio was higher than TP delivery ratio because significant amounts of TP was considered to be attached at soil as PO₄ ^- during delivery process from discharged point of nutrient source to main stream. As a results of correlation analysis, factors related to geomorphic characteristics had not statistical correlation with TN and TP delivery ratios. TN loading rate from living and specific stream flow had statistical negative and positive correlation, respectively, with TN delivery ratio. TP loading rates from all sources and from land cover and specific stream flow had statistical negative, negative and positive correlation, respectively. The specific stream flow represents the most strong correlation with nutrient delivery ratios. The regression equations to estimate delivery ratios for TN and TP were developed by including statistical correlated factors and showed high efficiency of 0.98 and 0.95 of coefficient of determination for TN and TP, respectively.

홍은미 Hong Eun Mi , 최진용 Choi Jin-yong , 유승환 Yoo Seung-hwan , 남원호 Nam Won Ho , 여진기 Yeo Jin Kie , 최인규 Choi In Gyu

DOI: JKWST Vol.52(No.5) 37-45, 2010

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Manure recycling as fertilizer is one of solutions for the environmental problem related with livestock manure treatment as well as the ocean dumping ban act prohibiting manure disposal to the ocean. For the manure disposal, forest area can be a candidate place because the area has a wide range of applicable sites. However, the manure application to the forest has a possibility of causing environmental impacts including water quality problems due to nutrient loading. Therefore it is necessary to investigate water quality impact from manure disposal to the forestry plantation. In this study, ground and soil water quality had been monitored in the bio-circulation experimental forest where low concentration liquid manure (LCLM) was applied. Soil and groundwater samples were collected and analyzed weekly from April to October in 2008 and 2009. The mean and variation of NO₃-N concentration in soil water of LCLM treatment places showed higher concentration than the reference places declining during growing season. In the case of groundwater from monitoring well in the downstream of disposal site, the NO₃-N concentration was 3.59 mg/L in 2008 and 3.26 mg/L in 2009 in average showing higher concentration than the reference well although the concentration was not exceed the national drinking water standard. To investigate the source of nitrate, δ¹⁵N isotope analysis was also implemented. Its result showed that the LCLM application could be the nitrate source requiring further long-term monitoring soil and water quality.

김영현 Kim Young Hyeon , 김진수 Kim Jin Soo , 장훈 Jang Hoon

DOI: JKWST Vol.52(No.5) 47-52, 2010

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The purpose of this study is to investigate characteristics of total phosphorus (TP) and phosphate phosphorous (PO₄-P) concentrations in ponded water and redox potential (Eh) in paddy soil during the growing season. The TP and PO₄-P concentrations showed twice peak values after basal dressing and tillering fertilization. The ratio of PO₄-P to TP showed low values (0.07～0.18), indicating that most of phosphorus is particlulate. The PO₄-P concentrations significantly decreased with dissolved oxygen (DO) concentrations. The Eh showed high values (179～636 mV) under non-ponded aerobic condition, but low values (74～112 mV) under ponded anaerobic condition The TP and PO₄-P concentrations in ponded water increased shortly after tillering fertilization even if phosphorus was not applied. This may be due to the release of dissolved phosphorus from the bottom sediment and its associated algal and water flea blooms under anaerobic condition. Therefore, proper water management should be needed shortly after tillering fertilization.

이진형 Lee Jin Hyung , 박찬기 Park Chan Gi

DOI: JKWST Vol.52(No.5) 53-60, 2010

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The effects of blast furnace slag, hwang-toh, and reinforcing fiber on the physical and mechanical properties of porous concrete using blast furnace slag coarse aggregates have been evaluated in this study. The effect of the depending on replacement ratio of blast furnace slag to cement was investigated such that the replacement ratio was varied to 0 %, 25 % and 50 %. Also, the replacement ratios of hwang-toh were 0, 20 and 30 %. The polyvinyl alcohol fiber was used for the reinforcing fiber. A series of pH, unit mass, and void ratio tests have been performed to study the physical properties of the porous concrete using blast furnace slag coarse aggregates with the polyvinyl alcohol fiber and the replacement ratios of blast furnace slag, hwang-toh, while a series of compressive tests have been performed to evaluate the strength property depending on polyvinyl alcohol fiber and the replacement ratios of blast furnace slag, hwang-toh. The test results indicated that the physical and mechanical properties of porous concrete using blast furnace slag coarse aggregates is affected by the replacement ratio of blast furnace slag, and the fiber contents. According to the tests with polyvinyl alcohol fiber contents, the void ratio was decreased and the compressive strength was upgraded.

노재경 Noh Jaekyoung

DOI: JKWST Vol.52(No.5) 61-68, 2010

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Jangchan reservoir is located in Okcheon county, Chungbuk province, of which watershed area is 29.4 km² from outside, and 5.1 km² from inside watershed, effective storage capacity is 392×10⁴ m³, paddy area to be irrigated is 474 ha. To determine inflows from Keumcheon weir located in outside watershed on an optimum level, a repeated procedure which is composed of simulation of inflows to Keumcheon weir, setting of range of water taking at Keumcheon weir, simulation of inflows to Jangchan reservoir, estimation of paddy water from Jangchan reservoir, and simulation of water storages in Jangchan reservoir was selected. Parameters of DAWAST model for simulating inflows to Jangchan reservoir were determined to UMAX of 315 mm, LMAX of 21 mm, FC of 130 mm, CP of 0.018, and CE of 0.007 with absolute sum of errors in reservoir water storages minimized using unconstrained Simplex method because of no inflows data. Inflows to Keumcheon weir were simulated to 2,132×10⁴ m³ on an annual average. Optimal range of water taking at Keumcheon weir to transfer to Jangchan reservoir were 0.81～50 mm/km²/d, which were summed up to 1,397×10⁴ m³ in 66% of total on an annual average. Inflows to Jangchan reservoir were simulated to 1,739×10⁴ m³ on an annual average of which were 80 % from Keumcheon weir of outside watershed. Requirements to paddy water from Jangchan reservoir were estimated to 543×10⁴ m³ on an annual average.

곽계환 Kwak Kae Hwan , 양동운 Yang Dong Woon , 김호선 Kim Ho Sun , 이호현 Lee Ho Hyun , 윤국현 Yun Kuk Hyun

DOI: JKWST Vol.52(No.5) 69-76, 2010

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The structural material with the highest possibility of new materials that will be used in the future construction field is fiber reinforced polymer. The current studies on FRP members by using such excellent material characteristics mostly focused on stability, composite problem, and durability of FRP members. The initially constructed FRP members secure excellent stability and durability compared to reinforced concrete and steel materials, but measures for defections during the periodical inspection, methods for detecting breakages, and maintenance and reinforcement are not insufficient. Accordingly, this study proposed a measurement system using the FRP sensor to evaluate the safety of the FRP modular box member, and applied the phased array ultrasonic technique to detect the defects and damage likely to occur during the performance period.

전지홍 Jeon Ji-hong , 최동혁 Choi Donghyuk , 임경재 Lim Kyung Jae , 김태동 Kim Tae-dong

DOI: JKWST Vol.52(No.5) 77-86, 2010

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Hydrologic Simulation Program-Fortran (HSPF) coupled with PEST which is optimization program was calibrated and validated at Bochung watershed by using monitoring data of water quantities and nutrient loading. Although the calibrated data were limited, model parameters of each land use type were optimized and coefficient of determinations were ranged from 0.94 to 0.99 for runoff, from 0.89 to 1.00 for TN loading, and from 0.92 to 1.00 for TP loading. The optimized hydrological parameters indicated that the forested land could retain rainfall within soil layer with high soil layer depth and infiltration rate compared with other land use type. Hydrological characteristics of paddy rice field are low infiltration rate and coefficient of roughness. The calibrated parameters related to nutrient loading indicated generation of nutrient pollution from agricultural area including upland and paddy rice field higher than other land use type resulting from fertilizer application. Overall PEST program is useful tool to calibrate HSPF automatically without consuming time and efforts.

현근우 Hyun Geun Woo , 박성빈 Park Sung Bin , 박정희 Park Jeong Hee , 전상호 Geon Sang Ho , 최재완 Choi Jae Wan , 김기성 Kim Ki-sung , 임경재 Lim Kyoung Jae

DOI: JKWST Vol.52(No.5) 87-95, 2010

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The optimum volume of sediment settling pond is determined by the maximum rainfall and surface peak rate runoff from crop field. Based on analysis of measured rainfall and runoff data, it was found that rainfall intensity of 2 mm/min would result in peak rate runoff from the agricultural field of study area. Optimum pond volume under various slope scenarios were determined using the WEPP model calibrated with measured flow and sediment data for the study watershed. For the agricultural field with the slope of 7 % and area of 2,600 m² at the study area, at least 6.4 m³ of sediment settling pond is needed as shown in this study. The results presented in this study could be used as a guide in designing appropriate volume of sediment settling pond at highland agricultural areas because both very detailed field measurement and calibrated WEPP model results are used in the analysis.

배승종 Bae Seung-jong , 윤성수 Yoon Seong-soo , 한이철 Han Yi-cheol , 윤홍일 Yoon Hong-il

DOI: JKWST Vol.52(No.5) 97-108, 2010

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The objective of this study is to develop evaluation indices which can be applied to analyze rational rehabilitation-policy directions of redundant farmlands. To achieve this objective, the main tasks of this research are 1) categorizing the redundant farmlands rehabilitation types 2) developing the evaluation indices of redundant farmlands rehabilitation 3) determining the weights of each index. The redundant farmlands rehabilitation types were classified into agricultural rehabilitation type, non-agricultural rehabilitation type and hybrid type which are called by agricultural income model, rural environment improvement model and hybrid model as development project name, respectively. The 5 parts and 21 indices for evaluation of redundant farmlands rehabilitation directions were extracted by case studies and experts brainstorming. The weights of each index were determined by Analytic Hierarchy Process (AHP). The developed evaluation indices were applied to study areas located on Yanghwa district of Gongju-city and Aewol district of Jeju-city. From the results of this study, it was ascertained that the evaluation indices developed in this study would help the decision-makers in the planning process of redundant farmlands rehabilitation directions.

배승종 Bae Seung-jong

DOI: JKWST Vol.52(No.5) 109-118, 2010

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The objectives of this study are to analyze and compare importance degrees of rural amenity resources for rural development project using AHP and ANP (Analytic Network Process) which can be applied a complex decision making problem. For this study, I chose the 5 rural development project types and the 10 rural amenity resources as major criteria and formed the ANP network from relations with criteria. The importance degree matrix were derived by the results of AHP and several ANP analysis. As the results of this study, the importance degrees of 10 rural amenity resources are determined and the indigenous product resource is identified as the most important resource in general rural development project.