• Journal of The Korean Society of Agricultural Engineers
• /
• v.63 no.3
• /
• pp.47-57
• /
• 2021

Drought monitoring over paddy field area is an important role as the frequency and intensity of drought due to climate change increases. This study analyzed the applicability of drought monitoring on paddy crops using MODIS-based field surveys. As a satellite-based drought index using evapotranspiration for quantitative drought determination, ESI (Evaporative Stress Index), was applied and calculated through the ratio of MODIS- based actual and potential evapotranspiration. For the irrigated areas of Idong, Gosam, Geumgwang, and Madun reservoirs the availability of irrigation water supply, ponding depth, precipitation, paddy growth were investigated for the paddy field within one grid of MODIS. In addition, the percentile-based ESI drought severity was calculated to compare the growth process of paddy and changes in the drought category of ESI. The Idong area was irrigated about a week later than other reservoirs for the period of water supply, transplanting, and water drainage and the ESI drought category tended to be different. The Gosam, Geumgwang, and Madun area expressed moderate drought prior to the farming season, and indicated normal as the water was supplied. During the water drainage, the drought category intensified, indicating that the water available on land was decreasing. These results demonstrated that the MODIS-based ESI could be an effective tool for agricultural drought monitoring over paddy field area.

• Journal of Animal Science and Technology
• /
• v.65 no.1
• /
• pp.258-270
• /
• 2023

Climate change has worsened droughts and floods, and created conditions more likely to lead to pathogen contamination of surface water and groundwater. Thus, there is a growing need to disinfect livestock water. Ultraviolet (UV) irradiation is widely accepted as an appropriate method for disinfecting livestock water, as it does not produce hazardous chemical compounds and kills pathogens. However, UV-based disinfection inevitably consumes electricity, so it is necessary to improve UV disinfection effectiveness. Aluminum-based reflective nanolens arrays that enhanced the effectiveness of a continuous-flow UV water disinfection system were developed using electrochemical and chemical processes, including electropolishing and two-step anodization. A continuous UV disinfection system was custom designed and the parts were produced using a three-dimensional printer. Electropolished aluminum was anodized at 40 and 80 V in 0.3 M oxalic acid, at 120 and 160 V in 1.0 M phosphoric acid, and at 200 and 240 V in 1.5 M citric acid. The average nanolens diameters (D) of the aluminum-based reflective nanolens arrays prepared using 40, 80, 120, 160, 200, and 240 V anodization were 95.44, 160.98, 226.64, 309.90, 296.32, and 339.68 nm, respectively. Simple UV reflection behind irradiated water disinfected Escherichia coli O157:H7 in water more than did the non-reflective control. UV reflection and focusing behind irradiated water using an aluminum-based reflective nanolens array disinfected E. coli O157:H7 more than did simple UV reflection. Such enhancement of the UV disinfection effectiveness was significantly effective when a nanolens array with D 226.64 nm, close to the wavelength of the irradiated UV (254 nm), was used.

• Journal of Korean Society on Water Environment
• /
• v.26 no.2
• /
• pp.243-251
• /
• 2010

Evapotranspiration and rainfall-runoff are the major components of hydrological cycle and thereby the changes of them can directly affect the wetness/dryness or runoff characteristics of basins. In this study the wetness/dryness in Geum river basin are classified by dint of cumulative probability density function of monthly moisture index and the long term changes of them are analyzed based on climatic water balance concept. The drought events in Geum river basin are selected through evaluation of monthly moisture index and the various hydrological properties of them are investigated in detail. Also the trends of time-series of climatic water balance components are examined by Seasonal Kendall test and the variability of hydrological cycle in Geum river basin during the recent decade is inquired. It is judged that the results of this study can be contributed to establishment of the counter plan against the future drought events as the fundamental information.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.11
• /
• pp.1322-1331
• /
• 2004

This paper presents studies on the design of water hydraulic system and components to replace oil with tap-water as the pressure transmission medium in hydraulic systems. In order to improve the performance of water hydraulic system, the thermal and hydraulic properties of tap-water are first investigated. Based on these characteristics, the design parameters, such as the clearances of the moving parts, the cross-sectional area of pipes and relative roughness, are proposed so that the performance of water hydraulic system is the same as that of oil. In addition, the operating ranges, which show the possibility of using water hydraulic system, are examined.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.2
• /
• pp.37-46
• /
• 2012

The change of rainfall pattern and hydrologic factors due to climate change increases the occurrence probability of agricultural reservoir water shortage. Water supply assessment of reservoir is usually performed current reservoir level compared to historical water levels or the simulation of reservoir operation based on the water budget analysis. Since each reservoir has the native property for watershed, irrigation district and irrigation water requirement, it is necessary to improve the assessment methods of agricultural reservoir water capability about water resources system. This study proposed a practical methods that water supply vulnerability assessment for an agricultural reservoir based on a concept of probabilistic reliability. The vulnerability assessment of water supply is calculated from probability distribution of water demand condition and water supply condition that influences on water resources management and reservoir operations. The water supply vulnerability indices are estimated to evaluate the performance of water supply on agricultural reservoir system, and thus it is recommended a more objective method to evaluate water supply reliability.

• Journal of Sensor Science and Technology
• /
• v.24 no.5
• /
• pp.331-341
• /
• 2015

In this paper, real-time water quality monitoring system of small water supply facilities based on IEEE 802.15.4e-2012 DSME MAC and IEEE 802.15.4g-2012 PHY standard is presented, which is capable to acquire for highly reliable water quality information in the wide outdoor areas for effective water quality management of small water quality facilities is distributed in the long distance and remote areas. Previously, Long distance transmission is difficult in most water quality sensor module is using RS-485 protocol. But with this system, even in harsh outdoor environment, it is possible to establish a radio wave sensor in a wide area network, and not only water quality sensor shall be connected to the wireless system, but also wireless integrated management system shall provide more effective way of management of the numerous small water supply facilities spread throughout the community, so that the administrator can remotely monitor the data of water turbidity, pH, residual chlorine in the water-supply, water-level, and generate alarm to cope with risks. The management of small water facilities is done by residents will be very effective to notice water quality information of small water facilities to residents.

• Proceedings of the Korea Water Resources Association Conference
• /
• 1992.07a
• /
• pp.443-447
• /
• 1992

This study describes the strategy for advanced decision support system (ADSS) development for integrated management of water resources and quality in reservoir systems. The developed ADSS consists of database that contain hydrologic data, observed operational data, and data to support specific reservoir operations simulation, optimization models, and water quality models. The optimization model, mass balance simulation model and water quality models are used in a general prototype ADSS, menu driven controlling framework that assists the user to specify and evaluate the alternative operational scenarios at one time. These alternative scenarios are evaluated by the models and the results are compared through the use of a graphical based display system. This graphical based system uses an icon based schematic representation of the system to organize the presentation of the results. The ADSS includes the ability to use monthly or weekly time periods of analysis for the models and it can use monthly historical or stochastically generated inflows.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.04a
• /
• pp.302-305
• /
• 2003

The purpose of this study was to assess the effect of surfactant on the rate of NAPLs(non-aqueous phase liquids) solubilization. The experimental variables were surfactant type, NAPLs type and water type. The main experimental designs were consists of two phases. The solubilization rate is sensitive to surfactant type based on this test. Used aqueous surfactants were solubilized and removed 72.77 to 89.90% of toluene, PCE(tetrachloroethylene) from the contaminated water during the test, respectively. T60 has higher and stable recovery ratio than SDS in surfactant type but, the micelle of the T60 is more weaker than that of SDS based on this study's results. And the solubilization rate in used water type was almost same.(deionized water, surface water).

• Ceramist
• /
• v.21 no.4
• /
• pp.416-426
• /
• 2018

Water splitting is regarded as one of the most environmentally benign routes for hydrogen production. Nevertheless, the low energy efficiency to produce the hydrogen has been a critical bottleneck, which is attributable to the multi-electron and multi-step reactions during water splitting reaction. In this respect, the development of efficient, durable, and inexpensive catalysts that can promote the reaction is indispensable. Extensive searching for new catalysts has been carried out for past decades, identifying several promising catalysts. Recently, researchers have found that conventional battery materials; particularly high-voltage intercalation-based cathode materials, could exhibit remarkable performance in catalyzing the water splitting process. One of the unique capabilities in this class of materials is that the valency state of metals and the atomic arrangement of the structure can be easily tailored, based on simple intercalation chemistry. Moreover, taking advantage of the rich prior knowledge on the intercalation compounds can offer the unexplored path to identify new water splitting catalysts.

• Journal of Korea Water Resources Association
• /
• v.45 no.8
• /
• pp.805-814
• /
• 2012

Most hydrologic data are obtained by ground observations. New observation methods are needed for some regions to overcome difficulties in accessibility and durability of long-term observation. In 2002, NASA launched twin satellites named GRACE which were designed to measure the gravitational field of the earth. Using the GRACE monthly gravity level-2 data, we calculated terrestrial water storage change (TWSC) of the Korean peninsula in various spatial smoothing radii (0 km, 300 km, 500 km). For the validation of GRACE-based TWSC, we compared it with land-based TWSC which was obtained using the ground observation data: precipitation and evaporation from WAMIS, and runoff from GLDAS. According to the mean square-error test, GRACE-based TWSC best fits the land-based one at 500 km smoothing radius. The variation of the terrestrial water storage in the Korean peninsula turned out to be 0.986 cm/month, which means that appropriate measures should be prepared for sustainable water resources management.