• Journal of the Korean Society of Tobacco Science
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• v.5 no.1
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• pp.73-78
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• 1983

In order to investigate the relation between weather factors, soil water, and tobacco yield grown by nonnulching and mulehing cultivations, a regression analysis was conducted for data collected from 8 years (1971 to 1978) for a flue-cured variety of Hicks. The soil water was calculated by Smith's method. 1 . Tobacco yield was largely correlated to soil water deficit during draught time for nonmulclung cultivation; $Y=6.146+8.6185\times-0.0925$\times2(R=0.935)^{***})$ 2. Tobacco yield was more largely correlated to soil water in flexible draght time interval than in fixed time interval during maximum growing phase.3. This field test was supposed that the optimal soil water condition was 65%field caps city. In this condition tobacco yield was 197. 1-216.5kg/10a for non-mulching cultivation. But the soil water deficit in draught season was little matter for mulching cultivation. The relation between xield and evaporation during May to June was Y: -1199.55+9.4 353$\times$:O. 0155$\times$2 (R=0.904") Maximum tobacco yield was expected to 223.6-251.4kg/10a for mulching cultivation. 5 . Tobacco required high temperature and light even in drying season (maximum growing phase) for mulching cultivation.tion.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.1
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• pp.64-79
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• 2016

The purpose of this study is to find the relationship between precipitation deficit, SPI(standardized precipitation index)-12 month, agricultural reservoir water storage deficit and agricultural drought-related big data, and to evaluate the usefulness of agricultural risk management through big data. For the long term drought (from January 2014 to September 2015), each data was collected and analysed with monthly and Provincial base. The minimum SPI-12 and maximum reservoir water storage deficit compared to normal year were occurred at the same time of July 2014, and August and September 2015. The maximum frequency of big data was occurred at June and July of 2014, and March and June to September of 2015. The maximum big data was occurred 1 month advanced in 2014 and 2 months advanced in 2015 than the maximum reservoir water storage deficit. The occurrence of big data was sensitive to spring drought from March, late Jangma of June, dry Jangma of July and the rainfall deficit of September 2015. The big data was closely related with the meteorological drought and agricultural drought. Because the big data is the in situ feeling drought, it is proved as a useful indicator for agricultural risk management.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.81-90
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• 1995

In order to provide the basic information for the water quality modeling, the water pollution indicators of Sin stream and Keumho river flowing through Taegu city were measured, and the Periodical variations of these indicators were studied under the condition of stagnating for 19 days. For this experiment, three sampling sites(Sungpook bridge, Mutae bridge and Gangchang bridge) were selected. Sungpook bridge is located most down the Sin stream, Mutae bridge and Gangchang bridge are located on the lower Keumho river. The results were as follows. 1. The values of water pollution indicators measured at Mutae bridge were pH 8.7, TSS 51mg/1, TS 383mg/1, Cl- 60.68mg/1, turbidity 32FTU, DO 8.58mg/1, oxygen deficit 2.02mg/1, COD 16.32mg/1, organic carbon 13.60mg/1. 2. At Gangchang bridge located down more than Mutae bridge, the values of these indicators were pH 8.0, TSS 26mg/1, TS 737mg/1, Cl- 90.59mg/1, turbidity 37FTU,DO 3.49mg/1, oxygen deficit 7.11mg/1, COD 28.02mg/1, organic carbon 14.28mg/1. 3. At Sungpook bridge, the values of these indicators were pH 8.3, TSS 145mg/1, TS 344mg/1, Cl- 32.51mg/1, turbidity 60FTU, DO 6.53mg/1, oxygen deficit 4.07mg/1, COD 43.79mg/1, organic carbon 11.03mg/1. 4. At Mutae bridge and Sungpook bridge of which initial DOs were high, DOs have decreased under the condition of stagnating for 7 days and increased after that time. On the contrary, at Gangchang bridge of which oxygen deficit was very high(7.11mg/l), DO have increased under the condition of stagnating for 13 days and decreased after that time 5. All the samples showed the quick decrease of CODs and organic carbons under the condition of stagnating for 19 days. Nevertheless, at Sungpook bridge ·of which initial COD was yeW high(43.79mg/1), the value of COD measured at the last day of experiment was still high(21.35mg/1) because of a large quantity of reducing inorganic matters. 6. All the samples didn't show the distinct decrease of turbidities because of a large quantity of nonbiodegradable inorganic solids.

• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.875-886
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• 2018

This study evaluated drought severity by bivariate frequency analysis using drought magnitude and precipitation deficit. A drought event was defined by Standardized Precipitation Index (SPI) and the precipitation deficit was estimated using reference precipitation corresponding to the SPI -1. In previous studies, drought magnitude and duration were used for bivariate frequency analysis. However, since these two variables have a largely linear relationship, extensibility of drought information is not great compared to the univariate frequency analysis for each variable. In the case of drought in 2015, return periods of 'drought magnitude-precipitation deficit' in the Seoul, Yangpyeong, and Chungju indicated severe drought over 300 years. However, the result of 'drought magnitude-duration' showed a significant difference by evaluating the return period of about 10, 50, and 50 years. Although a drought including the rainy season was seriously lacking in precipitation, drought magnitude did not adequately represent the severity of the absolute lack of precipitation. This showed that there is a limit to expressing the actual severity of drought. The results of frequency analysis for 'drought magnitude-precipitation deficit' include the absolute deficit of precipitation information, so which could consider being a useful indicator to cope with drought.

• Journal of Wetlands Research
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• v.19 no.3
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• pp.345-352
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• 2017

The average global temperature on Earth has increased by about $0.85^{\circ}C$ since 1880 due to the global warming. The temperature increase affects hydrologic phenomenon and so the world has been suffered from natural disasters such as floods and droughts. Therefore, especially, in the aspect of water deficit, we may require the accurate prediction of water demand considering the uncertainty of climate in order to establish water resources planning and to ensure safe water supply for the future. To do this, the study evaluated future water balance and water deficit under the climate change for Anseong river basin in Korea. The future rainfall was simulated using RCP 8.5 climate change scenario and the runoff was estimated through the SLURP model which is a semi-distributed rainfall-runoff model for the basin. Scenario and network for the water balance analysis in sub-basins of Anseong river basin were established through K-WEAP model. And the water demand for the future was estimated by the linear regression equation using amounts of water uses(domestic water use, industrial water use, and agricultural water use) calculated by historical data (1965 to 2011). As the result of water balance analysis, we confirmed that the domestic and industrial water uses will be increased in the future because of population growth, rapid urbanization, and climate change due to global warming. However, the agricultural water use will be gradually decreased. Totally, we had shown that the water deficit problem will be critical in the future in Anseong river basin. Therefore, as the case study, we suggested two alternatives of pumping station construction and restriction of water use for solving the water deficit problem in the basin.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.313-321
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• 2013

The Average daily PET (Potential evapotranspiration), evaluated based on the last 30 years meteorological data and the lysimeter experiment carried out by RDA during 11 years, of 9 regions in Korea for the tomato cultivated in greenhouse, was $3.41mm\;day^{-1}$. Two kinds of water saving irrigation standard (WSIS), deficit irrigation standard (DIS) and partial root-zone drying irrigation standard (PRDIS) that include the irrigation interval and the amount of irrigation water according to the region, soil texture and growing stage, were established. According to the DIS and PRDIS, the cultivator can save water up to 29.2% and 53.7%, respectively, for tomato cultivation in greenhouse compared to the full irrigation standard (FIS) which established in 1999. WSIS can be used easily by the cultivator without complicate procedures such as soil sampling and measurement of soil water status by expensive sensors. But the cultivator should care about irrigation method such as PRDI (partial root-zone drying irrigation) without yield decrease.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.6
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• pp.19-28
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• 2012

This study carried out farmland suitability analysis for southern-type garlic cultivation considering soil and temperature as well as water deficit conditions. The spatial extent was limited within the area derived by Kim et al. (2012) using just soil and temperature constraints. Daily soil moisture was simulated using a one-layer soil water balance model at a $100{\times}100m$ grid unit, and then annual water deficit was calculated from 2000 to 2010. The farmland suitability was classified as four steps: best suitable, suitable, possible, and low productive. As a result, total area of best suitable or suitable farmland was about 375,900 ha, and Gimje-si and Haenam-gun were appeared as the largest favorable area for southern-type garlic cultivation. The best suitable or suitable area at Haenam-gun, Goheung-gun, Shinan-gun, Namhae-gun, and Muan-gun, major production regions of southern-type garlic, were extracted as 20,187 ha, 13,018 ha, 4,715 ha, 1,319 ha, and 349 ha, respectively. On the other hand, the result showed that the adoption of sprinkler irrigation systems might be critical in cultivating the southern-type garlic at some regions having poor water balance.

• Journal of Korea Water Resources Association
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• v.39 no.5 s.166
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• pp.431-440
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• 2006

Recently, water conflicts are rapidly increasing and more serious. So, it needs to establish the reasonable water allocation rules and criteria. This study aims at performing inter-sectoral water allocation with a focus on economic effciency and social utility. To allocate water among the sectoral water uses, water shortage damage functions were estimated and then converged to the utility functions. Finally, each sectoral water uses are allocated by applying 'law equimarginal utility' to maximize social utility. Also weighting factor which reflects scale and characteristic of water demand in a region was estimated to perform the inter-regional water allocation. The water allocation rule was applied to the future water-deficit situation in Han-river basin. As a result, domestic water use was allocated more sufficient agricultural and industrial water use. Also, the water shortage occurs severely in the rural area like Gangwon-do because of its low urbanization and industrialization. This study suggests a alternative view of the economic water allocation which have difficulty under water supply mechanism in Korea.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.35-35
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• 2017

How do plants take up water from soils especially when water is scarce in soils? Plants have a strategy to respond to water deficit to manage water necessary for their survival and growth. Plants regulate water transport inside them. Water flows inside the plant via (i) apoplastic pathway including xylem vessel and cell wall and (ii) cell-to-cell pathway including water channels sitting in cell membrane (aquaporins). Water transport across the root and leaf is explained by a composite transport model including those pathways. Modification of the components in those pathways to change their hydraulic conductivity can regulate water uptake and management. Apoplastic barrier is modified by producing Casparian band and suberin lamellae. These structures contain suberin known to be hydrophobic. Barley roots with more suberin content from the apoplast showed lower root hydraulic conductivity. Root hydraulic conductivity was measured by a root pressure probe. Plant root builds apoplastic barrier to prevent water loss into dry soil. Water transport in plant is also regulated in the cell-to-cell pathway via aquaporin, which has received a great attention after its discovery in early 1990s. Aquaporins in plants are known to open or close to regulate water transport in response to biotic and/or abiotic stresses including water deficit. Aquaporins in a corn leaf were opened by illumination in the beginning, however, closed in response to the following leaf water potential decrease. The evidence was provided by cell hydraulic conductivity measurement using a cell pressure probe. Changing the hydraulic conductivity of plant organ such as root and leaf has an impact not only on the speed of water transport across the plant but also on the water potential inside the plant, which means plant water uptake pattern from soil could be differentiated. This was demonstrated by a computer simulation with 3-D root structure having root hydraulic conductivity information and soil. The model study indicated that the root hydraulic conductivity plays an important role to determine the water uptake from soil with suboptimal water, although soil hydraulic conductivity also interplayed.

• Journal of Korea Water Resources Association
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• v.52 no.5
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• pp.325-335
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• 2019

To characterize historical droughts in the conterminous United States (CONUS), we estimated the actual evapotranspiration ($ET_a$) in the CONUS using the generalized complementary relationship (GCR) for 1895-2016. The $ET_a$ estimates were compared against simulations from the Noah land surface model (LSM). In this study, the evapotranspiration (ET) deficit defined as the difference between the wet-environment ET ($ET_w$) and $ET_a$ was then normalized to calculate the Standardized Evapotranspiration Deficit Index (SEDI) across the CONUS for the years 1895-2016. The SEDI was compared to the Standard Precipitation Index (SPI) at various time scales. The results showed that the GCR $ET_a$ was slightly higher than the Noah LSM-simualted $ET_a$. As time scales increased, the correlation between the SEDI and the SPI was higher. This study suggests that the GCR has promise as a tool in the estimation of $ET_a$ and SEDI can be useful for the drought characterization.