전상민 Jun Sang Min , 송인홍 Song Inhong , 김계웅 Kim Kyeung , 황순호 Hwang Soon Ho , 강문성 Kang Moon Seong

DOI: JKWST Vol.57(No.3) 1-7, 2015

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The objective of this study was to compare fecal microbes survival in soil between compost surface application and soil incorporation. The survival experiment was conducted in six styrofoam beds (510 × 325 × 305 (mm) in size) filled with sandy loam soil. A half of six boxes were received by compost surface application, while the other half were treated with compost-soil mixture. Duplicated surface and surbsurface soil (20 cm depth) samples were collected at various interval up to 50 days and analyzed for the determination of fecal coliforms and E. coli numbers. As expected, surface applied beds demonstrated two to three magnitudes order greater in both the study microorganisms as compared to soil incorporated beds. Microbial inactivation rate of soil surface was twice as great as subsurface soil condition probably due to exposure to sun light and environmental conditions including moisture loss. When rainfall occurred, microbes on the surface were transported into soil along with water movement. It was concluded that surface compost application may be easier to apply but pose higher risk of human exposure to microbes. Winter compost application may be favorable in alleviating health risk by giving some time for inactivation compared to spring application.

홍세운 Hong Se Woon , 문애경 Moon Ae Kyung , 리송 Li Song , 이인복 Lee In Bok

DOI: JKWST Vol.57(No.3) 9-19, 2015

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Internal air temperature of greenhouse is an important variable that can be influenced by the complex interaction between outside weather and greenhouse inside climate. This paper focuses on a data-based model approach to predict internal air temperature of the greenhouse. External air temperature, solar radiation, wind speed and wind direction were measured next to an experimental greenhouse supported by the Electronics and Telecommunications Research Institute and used as input variables for the model. Internal air temperature was measured at the center of three sections of the greenhouse and used as an output variable. The proposed model consisted of a transfer function including the four input variables and tested the prediction accuracy according to the sampling interval of the input variables, the orders of model polynomials and the time delay variable. As a result, a second-order model was suitable to predict the internal air temperature having the predictable time of 20-30 minutes and average errors of less than ±1K. Afterwards mechanistic interpretation was conducted based on the energy balance equation, and it was found that the resulting model was considered physically acceptable and satisfied the physical reality of the heat transfer phenomena in a greenhouse. The proposed data-based model approach is applicable to any input variables and is expected to be useful for predicting complex greenhouse microclimate involving environmental control systems.

조재필 Cho Jaepil , 허용구 Her Younggu , 보쉬데이비드 Bosch David

DOI: JKWST Vol.57(No.3) 21-39, 2015

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허용구 Her Younggu

DOI: JKWST Vol.57(No.3) 41-54, 2015

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임성윤 Seongyoon Lim , 송창섭 Changseob Song , 김명환 Myeonghwan Kim

DOI: JKWST Vol.57(No.3) 55-63, 2015

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Embankment of agricultural reservoir started by four major rivers project. Most agricultural reservoirs must insure the agricultural water, they need must be ensured stability of embankment. Recently, there is a growing interest in seismic stability of structure by earthquake. Results of evaluation of the structural stability through seismic vibration test and numerical analysis, maximum displacement and the maximum acceleration is a similar trends. Appeared by increasing occurrence of the value of the displacement and acceleration of the structure with the result long period wave type in accordance with the seismic wave in the case of seismic waves, which shows the results of similar tendency as long period wave type consists of waveform seismic acceleration. Model test and numerical analysis results with in order to increase embankment agricultural reservoir, the displacement was found to ensure it is displayed within one percentage structural stability of the embankment.

홍은미 Hong Eun-mi , 남원호 Nam Won-ho , 최진용 Choi Jin-yong

DOI: JKWST Vol.57(No.3) 65-76, 2015

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Estimating water requirements for upland crops are characterized by standing soil moisture condition during the entire crop growth period. However, scarce rainfall and intermittent dry spells often cause soil moisture depletion resulting in unsaturated condition in the fields. Changes in rainfall patterns due to climate change have significant influence on the increasing the occurrence of extreme soil moisture depletion. Therefore, it is necessary to evaluate agricultural drought for upland crop water planning and management in the context of climate change. The objective of this study is to predict the impacts of climate change on agricultural drought for upland crops and changes in the temporal trends of drought characteristics. First, the changes in crop evapotranspiration and soil moisture in the six upland crops, such as Soybeans, Maize, Potatoes, Red Peppers, Chinese Cabbage (spring and fall) were analyzed by applying the soil moisture model from commonly available crop and soil characteristics and climate data, and were analyzed for the past 30 years (1981-2010), and Representative Concentration Pathways (RCP) climate change scenarios (2011-2100). Second, the changes on the temporal trends of drought characteristics were performed using run theory, which was used to compare drought duration, severity, and magnitude to allow for quantitative evaluations under past and future climate conditions.

이상현 Lee Sang-hyun , 최진용 Choi Jin-yong , 유승환 Yoo Seung-hwan

DOI: JKWST Vol.57(No.3) 77-86, 2015

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The agricultural water management generally has focused on water resources for crop production but it could be affected by the food consumption pattern. The aim of this study is to estimate virtual water consumption for food consumption and calorie supply using the water footprint and virtual water concept. In addition, we estimated the virtual water requirements for increasing the food and calorie self-sufficiency adjusted by the government for food security. About 330.0 m³/cap/yr of virtual water was consumed for the main foods consumption in 1985, and it was increased to 450.0 m³/cap/yr in 2010. The rate of virtual water consumption by meats consumption was 28 % in 1985 but it was increased to 54 % in 2010. In other words, the total virtual water consumption by foods consumption was increased from 1985 to 2010 with the high rate of meats consumption. The average 1.29 m³ of virtual water was consumed for supplying 1 calorie per capita in 2010 but about 10.1 m³/cal of virtual water was consumed by only bovine meats consumption. The food self-sufficiency is the main factor for food security in Korea. About 46.5 Mm³ and 393.9 Mm³ of virtual water were required in order to increase the food and calorie self-sufficiency of wheat by 1 % individually. This study showed the water consumption was related to food consumption and calorie supply pattern, and these results could be used as the indices for the agricultural water management considering the change of eating habit and food security.

김현태 Hyuntai Kim , 서동욱 Donguk Seo , 류찬호 Chanho Yoo , 김석열 Seogyeol Kim

DOI: JKWST Vol.57(No.3) 87-92, 2015

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Cultivation on reclaimed tidal land is often difficult in the problem such as high salinity of soil, bad drainage because of high level of groundwater. Many researches have been made efforts to solve these problems, but effect of improvement is low and practicality is insufficient. In this study, through numerical analysis of the transport properties of salt and water, we suggested underground drainage of the reclaimed land and the desalination promotion methods in the soil. The results of characteristic of desalination and seepage analysis of underdrain show that underdrain is able to increase twice of the underground seepage amount when installing perforated pipe with horizontal filter (width 50cm) more than installing only the perforated pipe. For soil which coefficient of permeability is below 1×10^-4 cm/s that desalination with pond water is not possible, a method to increase the permeability of the soil is necessary. Therefore, it was concluded that application of underdrain using perforated pipe with horizontal filter would be low-cost and practical.

임성윤 Seongyoon Lim , 송창섭 Changseob Song , 김명환 Myeonghwan Kim

DOI: JKWST Vol.57(No.3) 93-100, 2015

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The object of this paper is to study the shear characteristics of the weathered granite soil. To this end, a series of consolidated undrained triaxial compression tests are carried out to investigate the shear parameters-cohesion and internal friction angle-for the degree of saturation and degree of weathering. From the results, it is found that the shear parameters of weathered granite soil are influenced on the degree of saturation, degree of weathering and disturbance. Especially, internal friction angle is more influenced on the upper factors than cohesion. And shear parameters are more acted on the degree of saturation than the degree of weathering in the test range. It is, therefore, recommended that must be considered the conditions of granite soil- degree of saturation, degree of weathering and disturbance etc-in case of the calculation of bearing capacity, stability analysis and other designs with shear parameters.

박진선 Park Jin-seon , 전정배 Jeon Jeong-bae , 윤성수 Yoon Seong-soo

DOI: JKWST Vol.57(No.3) 101-108, 2015

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The purpose of this study was to evaluate the safety of the small reservoir, which is distributed in a rural area, based on systemic reliability. It has been estimated that safety of respective reservoir the calculation of failure probability for individual reservoirs can evaluate the safety of the reservoir of the study area. The change of safety for watershed could be figured out as that result. Probability of failure was increased from 3.90×10^-5 to 1.35×10^-4 in Naesu-inpyung reservoir, from 1.33×10^-5 to 4.77×10^-5 in Buyeon reservoir and from 4.24×10^-5 to 2.55×10^-2 in Dalakmal respectively. From the results, the collapse of the upper stream reservoir was analyzed qualitatively that may affect the safety of the reservoir on the downstream area.

정충길 Jung Chung Gil , 이용관 Lee Yong Gwan , 김성준 Kim Seong Joon , 장철희 Jang Cheol Hee

DOI: JKWST Vol.57(No.3) 109-120, 2015

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Spatial heterogeneous characteristics of solar radiation energy from Climate Change gives rise to energy imbalance in the general ecological system including water resources. This study is to estimate the CO₂ flux of South Korea using Terra MODIS image and to assess the reliability of MODIS data from the ground measured CO₂ flux by eddy covariance flux tower data at 3 locations (two at mixed forest area and one at rice paddy area). The MODIS Gross Primary Productivity (GPP) product (MOD17A2), 8-day composite at 1-km spatial resolution was adopted for the spatial CO₂ flux generation. The MOD17A2 data by noise like cloud and snow in a day were tried to fill by Inverse Distance Weighted (IDW) method from valid pixels and the damping effect of MOD17A2 data were corrected by Quality Control (QC) flag. The MODIS CO₂ flux was estimated as the sum of GPP and Re (ecosystem respiration) by Lloyd and Taylor method (1994). The determination coefficient (R²) between MODIS CO₂ and flux tower CO₂ for 3 years (2011~2013) showed 0.55 and 0.60 in 2 mixed forests and 0.56 in rice paddy respectively. The CO₂ flux generally fluctuated showing minus values during summer rainy season (from July to August) and maintaining plus values for other periods. The MODIS CO₂ flux can be a useful information for extensive area, for example, as a reliable indicator on ecological circulation system.

김학관 Kim Hak Kwan , 정한석 Jeong Han Seok , 배승종 Bae Seung Jong

DOI: JKWST Vol.57(No.3) 121-127, 2015

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The objective of this study is to suggest the water quality criteria of total nitrogen in order to efficiently manage the nutrient pollution in the stream. For this, correlations between water quality parameters were examined using the water quality data collected from the water quality monitoring network in the four rivers between 2003 and 2012. T-N showed positive correlations with T-P (0.636), COD (0.577), BOD (0.574), TOC (0.440), and SS (0.367). The statistical analysis including percentile analysis for the T-N and T-P concentrations was utilized to develop the water quality criteria of T-N. The feasibility of the suggested water quality criteria was evaluated by calculating the achievement rate to water quality target at the representative points in mid-watershed, then the draft water quality standard of T-N was suggested. The suggested water quality standard of T-N in the stream may be used to efficiently control the nutrient pollution in the public water body.