• Magazine of the Korean Society of Agricultural Engineers
• /
• v.31 no.2
• /
• pp.82-91
• /
• 1989

This study was carried out to get the basic information of irrigation plans for the red pepper, such as optimum irrigation level and irrigation requirement in Taegu and Kyungpook province. In this study, red peppers were cultivated in 6 PVC pot lysimeters filled with 60cm deep clay loam soil. Four tensiometers were installed in each plot to measure the soil water pressure head. Field measurements were made during the period June 6 to October 31, 1988 at the experimental farm of Kvungpook National University. Six levels of irrigation were used. They were PF 1.8-2.0, PF 2.2-2.4, PF 2.8-3.0, FC-PF.1.7, FC-PF 2.2, and FC-PF 2.7. The results obtained from this study are summarized as follows : 1. In case of irrigation levels of narrow ranges of water contents, the higher the soil water content was, the larger the ET was. Hut in case of the irrigation levels returning to the field capacity, the lager the PF value of irrigation point was, the larger the ET was. Considering ET, yield and weight per fruit, the latter is much better than the former irrigation method. 2. The mean daily ET and mean ET ratio for each 10-day period showed that the maximum value occured in the last of August. The ranges of those were 3.74-14.64 mm/day and 0.87-3.40, respectively. These values showed that small during the early stage of growth, large during the middle stage and getting smaller in the last stage. 3. In case of irrigation levels of narrow ranges of water contents, the increase of irrigation water supplied increased the ET. The relationship between the two showed nearly straight line. Most of irrigated water was consumed as ET and the rest as percolation. But, in case of irrigation levels returning to the field capacity, the higher the PF value of irrigation point was, the larger the ET ratio was. However, their relationship didn't show straight line. 4. The irrigation level of PC - PP 2.7 was found to be the optimum irrigation level with respect to the yield, the weight per fruit, stem length, irrigation requirement and percolation quantity. In this case, mean daily ET and mean ET ratio were 6.79 mm/day (total 10052 mm) and 1.67, respectively. The maximum mean daily ET and mean ET ratio for 10-day period were 14.64 mm/day and 3.40, respectively, in the last of August, and the maximum daily ET was 2126 mm/day on August 24. 5. In case of PC - PP 2.7 which is found the optimum irrigation level, mean irrigation water required, mean ET and mean percolation water quantity were 7.44 mm/day, 6.79 mm/day(91.3% of irrigation water), and 0.38 mm/day (5.5% of it), respectively.

• Journal of Bio-Environment Control
• /
• v.6 no.3
• /
• pp.205-215
• /
• 1997

An accurate transpiration model for greenhouse tomato crop, which is liable to transpiration depression and yield loss because of low solar radiation and high humidity, could be an efficient tool for the optimum control of greenhouse climate and for the optimization of Irrigation scheduling. The purpose of this study was to develop transpiration model of greenhouse tomato and to carry out the experimental verification. The formulas to calculate the canopy transpiration and temperature simultaneously were derived from the energy balance of canopy. Transpiration and microclimate variables such as net radiation, solar radiation, humidity, canopy and air temperature, etc. were simultaneously measured to estimate parameters of model equations and to verify the suggested model. Leaf boundary layer resistance was calculated as a function of Nusselt number and stomatal diffusive resistance was parameterized by solar radiation and leaf-air vapor pressure deficit. The equation for stomatal diffusive resistance could explain more than 80％ of its variation and the calculated stomatal diffusive resistance showed good agreements with the measured values in situations independent of which the constants of the equation were estimated. The canopy net radiation calculated by Stanghellini's model with slight modification agreed well with the measured values. The present transpiration model, into which afore-mentioned component equations were assembled, was found to predict the canopy temperature, instantaneous and daily transpiration with considerable accuracy in greenhouse climates.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.4
• /
• pp.1151-1159
• /
• 2014

In this study, two global simple indices are used to investigate climate variability and change in observations. Land-Ocean Contrast (LOC) is an index of area-averaged surface temperature contrast between land and ocean. Meridional Temperature Gradient (MTG) is defined as the mean meridional temperature gradient in the Northern Hemisphere from mid to high latitude and sub-tropical zonal bands. These indices have direct or indirect effects on changing in atmospheric circulations and atmospheric moisture transport from north-south or east-west into East Asia (EA). In addition, warm season hydrometeorology in EA is highly associated with water supplies for coupled human and natural systems including drinking water, irrigation, hydropower generation as well as fisheries. Therefore, in this study, we developed an empirical separation approach for summer rainfall from typhoon and monsoon. An exploratory analysis was also conducted to identify the regional patterns of summer monsoon precipitation over the Korean peninsula within the context of changes in different types of temperature gradients. The results show significant and consistent changes in summer monsoon rainfall during the summer season (June-September) in South Korea.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.2
• /
• pp.128-133
• /
• 2000

This study was conducted to investigate the adsorptive characteristics with cadmium in different levels of organic matter and lime in soil. And in order to identify the effect of soil ameliorators on cadmium uptake in rice plants, compost and lime were treated. Plants were grown at two soil textures(sandy loam and clay loam) with irrigation water containing $0.01\;mg\;L^{-1}$ of cadmium and treatments of two irrigation systems(intermittent irrigation and continuous submersion). The adsorption capacity of cadmium by soil was increased in proportion to initial concentration of solution, and it was higher at clay soil compared to loamy soil. The adsorption rate of cadmium by soil was increased with increasing the concentration of organic matter and lime in soil, highly increased at the both organic matter and lime treatment. Soil pH was negatively correlated with the cadmium contents of the both shoot and brown rice while Eh was positively correlated with those. In the harvest season, cadmium contents in the both leaves and brown rice were lower in the clay sail plots than sandy soil plots, and the continuous submersion plots were lower than intermittent irrigation plots. Cadmium uptake was highly reduced at the compost and lime mixture plot compared to other treatments among the continuous submersion plots. The cadmium content of shoot was positively correlated with that of brown rice in the harvest season.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2007.05a
• /
• pp.241-245
• /
• 2007

국내 홍수빈도 분포의 매개변수 추정에서 지점추정(at-site estimate) 방법은 유량 자료의 부족으로 발생하는 표본오차(sampling error)가 크기 때문에 충분한 유량 자료를 보유한 지점에 한하여 제한적으로 사용되고 있다. 대안으로 동질성을 가진 유역의 유량 자료를 모아 지역 매개변수를 추정하는 지수홍수법(Index Flood Method)이 제안되기도 하였으나, 이질성이 큰 우리나라의 유역특성 때문에 적용이 쉽지 않다. Stedinger와 Tasker가 1986년 제안한 GLS(Generalized Least Square) 기법은 유역을 동질지역으로 구분할 필요가 없으며 지점들간의 상관관계와 이분산성을 고려할 수 있어, 국내 홍수빈도 해석을 위해서 꼭 도입해야할 기법으로 생각된다. 본 연구에서는 기존의 GLS 기법의 단점을 보완한 Bayesian-GLS 기법을 이용하여, 국내 대유역에 골고루 위치하며 댐의 영향을 받지 않는 31개 지점의 연최대 일유량 시계열의 L-변동계수(L-moment coefficient variation)와 L-왜도계수(L-moment coefficient skewness)를 추정할 수 있는 회귀모형을 제안하였다. 위 회귀모형을 구성하기 위한 유역특성으로는 유역면적, 유역경사, 유역평균강우 등을 사용하였다. Bayesian-GLS (B-GLS) 적용 결과를 OLS(Ordinary Least Square) 및 Bayesian-GLS 기법에서 지점간의 상관관계를 고려하지 않는 Bayesian-WLS(Weighted Least Square)와 비교 평가하여 그 우수성을 입증하였다. 따라서 본 연구에서 제안된 B-GLS에 의한 지역회귀모형은 국내의 미계측유역이나 또는 관측 길이가 짧은 계측유역의 홍수빈도분석을 위해 매우 유용할 것으로 기대된다.년 홍수 피해가 발생하고 있지만, 다른 한편 인구밀도가 높고 1인당 가용 수자원이 상대적으로 적기 때문에 국지적 물 부족 문제를 경험하고 있다. 최근 국제적으로도 농업용수의 물 낭비 최소화와 절약 노력 및 타 분야 물 수요 증대에 대한 대응 능력 제고가 매우 중요한 과제로 부각되고 있다. 2006년 3월 멕시코에서 개최된 제4차 세계 물 포럼에서 국제 강 네트워크는 "세계 물 위기의 주범은 농경지", "농민들은 모든 물 위기 논의에서 핵심"이라고 주장하고, 전 프랑스 총리 미셀 로카르는 "...관개시설에 큰 문제점이 있고 덜 조방적 농업을 하도록 농민들을 설득해야 한다. 이는 전체 농경법을 바꾸는 문제..."(segye.com, 2006. 3. 19)라고 주장하는 등 세계 물 문제 해결을 위해서는 농업용수의 효율적 이용 관리가 중요함을 강조하였다. 본 연구는 이러한 국내외 여건 및 정책 환경 변화에 적극적으로 대처하고 물 분쟁에 따른 갈등해소 전략 수립과 효율적인 물 배분 및 이용을 위한 기초연구로서 농업용수 수리권과 관련된 법 및 제도를 분석하였다.. 삼요소의 시용 시험결과 그 적량은 10a당 질소 10kg, 인산 5kg, 및 가리 6kg 정도였으며 질소는 8kg 이상의 경우에는 분시할수록 비효가 높았으며 특히 벼의 후기 중점시비에 의하여 1수영화수와 결실율의 증대가 크게 이루어졌다. 3. 파종기와 파종량에 관한 시험결과는 공시품종선단의 파종적기는 4월 25일부터 5월 10일경까지 인데 이 기간중 일찍 파종하는 경우에 파종적량은 10a당 약 8${\ell}$이고 늦은 경우에는 12${\ell}$ 정도였다. 여기서 늦게 파종한 경우 감수의 가장 큰 원인은 1수영화수가 적어지기 때문이었다. 4. 건답직파에 대한 담수상태로 관수를 시작하는 적기는 파종후

• Journal of Biosystems Engineering
• /
• v.8 no.1
• /
• pp.61-69
• /
• 1983

A system dynamic model was developed to predict food grain production under the dynamic consideration of the production circumstance and inputs such as farm population, investment on agriculture, arable land, extensive technology and weather. By using the model, the variation of the food grain production from 1978 to 2008 was examined. The results of the model output says it is desirable that the persistent and long-term program should be studied to get necessary food grain production under the variational inputs and circumstances.

• Korean Journal of Agricultural Science
• /
• v.14 no.1
• /
• pp.68-80
• /
• 1987

This study was carried out to investigate the evapotranspiration and variations of soil moisture contents for soybeans. The relationship between actual evapotranspiration obtained by the water balance equation and estimated evapotranspiration obtained by the soil moisture model was analyzed. The results obtained were summarized as follows; 1. The total amount of actual evapotranspiration of soybeans during growing season was 405.7mm. The total amount of reference crop evapotranspiration of soybeans that was estimated by Pan evaporation and Hargreaves method were 547.8 mm and 586.8 mm, respectively. Crop coefficient during growing season were shown on Table 1. 2. Measured actual evapotranspiration of soybean during growing season was 405.7 mm and estimated actual evapotranspiration by pan evaporation and Hargreaves method were 424.7 mm, and 426.1mm, r3 respectively. 3. The variations of soil moisture content for soybeans were high at 10cm layer, as compared with those at 30cm and 50cm layers. Because discrepancy between the variations of soil moisture content predicted by model and observed by soil moisture meter was still great, it is required to study the consumptive types of soil moisture at each root depth.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.18 no.4
• /
• pp.348-356
• /
• 2016

Carbon dioxide ($CO_2$) gases concentration in atmosphere has been growing since preindustrial times. By sequestering a large amount of atmospheric carbon (C), terrestrial ecosystems are thought to offer a mitigation strategy for reducing global warming. Woody agro-ecosystems such as fruit tree are among the least quantified and most uncertain elements in the terrestrial carbon cycle. $CO_2$ and energy fluxes were measured by the eddy covariance method on a 15-year old apple orchard of South Korea in 2006. Environmental parameters (net radiation, precipitation, etc.) were measured along with fluxes. The results showed that during late June, the ability to sequestrate C was significant at an apple orchard ecosystem and it reached on the peak of $-6.5g\;C\;m^{-2}\;d^{-1}$. We found that in the apple orchard, the daily average of net ecosystem exchange of $CO_2$ (NEE) and cumulative NEE on a yearly basis were $-1.1g\;C\;m^{-2}$ and $-396.9g\;C\;m^{-2}$, respectively. These results reveal that there is high carbon sequestration in the apple orchard of South Korea, which is the same magnitude with repect to that of a natural forested ecosystem of the same biome rank (temperate-humid deciduous forest).

• Journal of the Korean Institute of Landscape Architecture
• /
• v.43 no.4
• /
• pp.98-111
• /
• 2015

Urban environmental problems such as flooding, depletion of ground water, pollution of urban streams and the heat island effect caused by urban development and climate change can be mitigated by the improvement of the urban water cycle. For the effective planning of water cycle management it is necessary to establish aerial Hydrotope Maps, with which we can estimate the status and change of the water allowance for any site. The structure of the German water balance model BAGLUVA, which is based on soil and vegetation, was analyzed and the input data and boundary condition of the model was compared with Korean data and research results. The BAGLUVA Model consists of 5 Input categories (climate, land use, topography, soil hydrology and irrigation). The structure and interconnection of these categories are analyzed and new concepts and implementation methods of topographic factor, maximum evapotranspiration ratio, effective rooting depth and Bagrov n parameter was compared and analyzed. The relation of real evapotranspiration ($ET_a$)-maximum evapotranspiration ($ET_{max}$) - precipitation (P) was via Bagrov n factor represented. The aerial and land use oriented Hydrotope Map can help us to investigate the water balance of small catchment areas and to set goals for volume of rainwater management and LID facilities effectively in the city. Further, this map is a useful tool for implementing water resource management within landscape and urban planning.

• Journal of Korea Water Resources Association
• /
• v.43 no.8
• /
• pp.733-745
• /
• 2010

Seasonality of hydrologic extreme variable is a significant element from a water resources managemental point of view. It is closely related with various fields such as dam operation, flood control, irrigation water management, and so on. Hydrological frequency analysis conjunction with partial duration series rather than block maxima, offers benefits that include data expansion, analysis of seasonality and occurrence. In this study, nonstationary frequency analysis based on the Bayesian model has been suggested which effectively linked with advantage of POT (peaks over threshold) analysis that contains seasonality information. A selected threshold that the value of upper 98% among the 24 hours duration rainfall was applied to extract POT series at Seoul station, and goodness-fit-test of selected GEV distribution has been examined through graphical representation. Seasonal variation of location and scale parameter ($\mu$ and $\sigma$) of GEV distribution were represented by Fourier series, and the posterior distributions were estimated by Bayesian Markov Chain Monte Carlo simulation. The design rainfall estimated by GEV quantile function and derived posterior distribution for the Fourier coefficients, were illustrated with a wide range of return periods. The nonstationary frequency analysis considering seasonality can reasonably reproduce underlying extreme distribution and simultaneously provide a full annual cycle of the design rainfall as well.