Efficiency Evaluation of Vegetative Filter Strip for Non-point Source Pollutant at Dense Upland Areas - Focused on Non-point Source Management Area Mandae, Gaa, and Jaun Basins -
정연지 Jeong Yeonji , 이동준 Lee Dongjun , 강현우 Kang Hyunwoo , 장원석 Jang Won Seok , 홍지영 Hong Jiyoung , 임경재 Lim Kyoung Jae
Efficiency Evaluation of Vegetative Filter Strip for Non-point Source Pollutant at Dense Upland Areas - Focused on Non-point Source Management Area Mandae, Gaa, and Jaun Basins -
정연지 Jeong Yeonji , 이동준 Lee Dongjun , 강현우 Kang Hyunwoo , 장원석 Jang Won Seok , 홍지영 Hong Jiyoung , 임경재 Lim Kyoung Jae
A vegetative filter strip (VFS) is one of the best management practices (BMPs) to reduce pollutant loads. This study aims to assess the effectiveness of VFS in dense upland field areas. The study areas are agricultural fields in the Maedae (MD), Gaa (GA), and Jaun (JU) watersheds, where severe sediment yields have occurred and the Korean government has designated them as non-point management regions. The agricultural fields were divided into three or four clusters for each watershed based on their slope, slope length, and area (e.g., MD1, MD2). To assess the sediment trapping (STE) and pesticide reduction efficiency (PRE) of VFS, the Vegetative Filter Strip Modeling System (VFSMOD) was applied with three different scenarios (SC) (SC1: VFS with rye vegetation; SC2: VFS with rye vegetation and a gentle slope in VFS range; and SC3: VFS with grass mixture). For SC1, there were relatively short slope lengths and small areas in the MD1 and GA3 clusters, and they showed higher pollutant reduction (STE>50%, PRE>25%). For SC2 and SC3, all clusters in GA and some clusters (MD1 and MD3) in MD show higher pollutant reduction (>25%), while the uplands in JU still show a lower pollutant (<25%). With correlation analysis between geographic characteristics and VFS effectiveness slope and slope length showed relative higher correlations with the pollutant efficiency than a area. The results of this study implied that slope and slope length should be considered to find suitable upland conditions for VFS installations.
Improvement of Drought Operation Criteria in Agricultural Reservoirs
문영식 Mun Young-sik , 남원호 Nam Won-ho , 우승범 Woo Seung-beom , 이희진 Lee Hee-jin , 양미혜 Yang Mi-hye , 이종서 Lee Jong-seo , 하태현 Ha Tae-hyun
Currently, the operation rule of agricultural reservoirs in case of drought events follows the drought forecast warning standard of agricultural water supply. However, it is difficult to preemptively manage drought in individual reservoirs because drought forecasting standards are set according to average reservoir storage ratio such as 70%, 60%, 50%, and 40%. The equal standards based on average water level across the country could not reflect the actual drought situation in the region. In this study, we proposed the improvement of drought operation rule for agricultural reservoirs based on the percentile approach using past water level of each reservoir. The percentile approach is applied to monitor drought conditions and determine drought criteria in the U.S. Drought Monitoring (USDM). We applied the drought operation rule to reservoir storage rate in extreme 2017 spring drought year, the one of the most climatologically driest spring seasons over the 1961-2021 period of record. We counted frequency of each drought criteria which are existing and developed operation rules to compare drought operation rule determining the actual drought conditions during 2016-2017. As a result of comparing the current standard and the percentile standard with SPI6, the percentile standard showed severe-level when SPI6 showed severe drought condition, but the current standard fell short of the results. Results can be used to improve the drought operation criteria of drought events that better reflects the actual drought conditions in agricultural reservoirs.
Integral Design and Structural Analysis for Safety Assessment of Domestic Specialized Agrivoltaic Smart Farm System
이상익 Lee Sang-ik , 김동수 Kim Dong-su , 김태진 Kim Taejin , 정영준 Jeong Young-joon , 이종혁 Lee Jong-hyuk , 손영환 Son Younghwan , 최원 Choi Won
Renewable energy systems aim to achieve carbon neutrality and replace fossil fuels. Photovoltaic technologies are the most widely used renewable energy. However, they require a large operating area, thereby decreasing available farmland. Accordingly, agrivoltaic systems (AVSs)―innovative smart farm technologies that utilize solar energy for crop growth and electricity production―are attracting attention. Although several empirical studies on these systems have been conducted, comprehensive research on their design is lacking, and no standard model suitable for South Korea has been developed. Therefore, this study created an integral design of AVS reflecting domestic crop cultivation conditions and conducted a structural analysis for safety assessment. The shading ratio, planting distance, and agricultural machinery work of the system were determined. In addition, national construction standards were applied to evaluate their structural safety using a finite element analysis. Through this, the safety of this system was ensured, and structural considerations were put forward. It is expected that the AVS model will allow for a stable utilization of renewable energy and smart farm technologies in rural areas.
Estimation and Spatial Distribution of Monthly FDSI Using AMSR2 Satellite Image-based Soil Moisture in South Korea
천범석 Chun Beomseok , 이태화 Lee Taehwa , 정광준 Jeong Kwangjune , 신용철 Shin Yongchul
In this study, we estimated the monthly FDSI (Flash Drought Stress Index) for assessing flash drought on South Korea using AMSR2(Advanced Microwave Scanning Radiometer 2) satellite-based soil moisture footprints. We collected the AMSR2 soil moisture and climate-land surface data from April to November 2018 for analyzing the monthly FDSI values. We confirmed that the FDSI values were high at the regions with the high temperature/evapotranspiration while the precipitation is relatively low. Especially, the regions which satisfied an onset of flash drought (FDSI≧0.71) were increased from June. Then, the most of regions suffered by flash drought during the periods (July to August) with the high temperature and evapotranspiration. Additionally, the impacts of landuse and slope degree were evaluated on the monthly FDSI changes. The forest regions that have the steep slope degree showed the relatively higher FDSI values than the others. Thus, our results indicated that the the slope degree has the relatively higher impact on the onset and increasing of flash drought compared to the others.
An Experimental and Numerical Study on the Behavior Characteristics of Single-span Plastic Greenhouse under Snow Load
송호성 Song Hosung , 김유용 Kim Yu-yong , 유석철 Yu Seok-cheol , 임성윤 Lim Seong-yoon
In this study, the loading test and structural analysis were performed on the snow load and the results were compared. The load plates were loaded on the roof surface of the model, and structural analysis was performed under the same conditions. The result of loading test, the maximum displacement was observed in the center of the top, and the maximum stress was observed near the bottom point. Displacement and stress were found to have a high linear relationship with the load. Comparing the structural analysis results with the loading test results, the maximum displacement difference is 4.5% and the maximum stress difference is 10.2%. It is expected that closer results can be derived if the boundary conditions for the longitudinal direction of the model are clarified during experiments and analysis.
Physical Habitat Assessment of Bokha Downstream Reach Considering Life Cycle Stages of Zacco platypus Using PHABSIM
이혁진 Lee Hyeokjin , 박진석 Park Jinseok , 장성주 Jang Seongju , 홍록기 Hong Rokgi , 송인홍 Song Inhong
The objectives of this study were to assess physical habitat suitability of fish species for different life cycle stages and to suggest appropriate ecological stream flows in a Bokha downstream reach. A dominant species of Zacco platypus was selected as the study fish of which three stages of spawning, juvenile and adult in life cycle were considered into assessment. The stream hydraulic environment was calibrated with HEC-RAS before the PHABSIM simulation. The hydraulics of flow velocity and depth were used to estimate Weighted Usable Area (WUA) by multiplying respective habitat suitability indices with stream area. Overall the WUAs tend to be great in gentle slopes with relatively shallow water depth regions. Maximum WUAs, ie, candidate for ecological flow rates were 1 ㎥/s, 7 ㎥/s and 8 ㎥/s for the respective spawning, juvenile and adult stages of Zacco platypus. Since the ecological flow rates for juvenile and adult stages appeared to be is greater than the abundant flow rate (3.67 ㎥/s) for the study reach, additional water supply may be needed but should be cautious to avoid the spawning period of Apr through May from the stream water management perspective.
Strength Evaluation of Concrete Containing Ferronickel Slag Aggregate
최민건 Choi Min Guen , 손진수 Son Jin-su , 조봉석 Cho Bong Suk , 이진영 Lee Jin-young
For sustainable development in the construction industry, blast furnace slag has been used as a substitute for cement in concrete. In contrast, ferronickel slag, which is the by-product generated during smelting to ferronickel used in the manufacturing of stainless steel and nickel alloys, has a limitation to use as a binder and an aggregate due to its expansive characteristics. Recently, stabilization technology of ferronickel slag has been improved and studies have been carried out to utilize ferronicke slag as fine aggregate in concrete. Therefore, in this study, basic mechanical properties of concrete used in ferronickel slag aggregate was evaluated. The compressive strength (24, 30, 40 MPa) and replacement rate of ferronickel slag aggregate (0, 10, 25, 50%) were considered as experimental variables. As a result of test, concrete replaced fine aggregate with 25% ferronickel slag aggregate showed superior performance in the compressive strength and flexural strength.
