남원호 Nam Won-ho , Tsegaye Tadesse , Brian D. Wardlow , 장민원 Jang Min-won , 홍석영 Hong Suk-young

DOI: JKWST Vol.57(No.4) 1-9, 2015

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The development of drought index that provides detailed-spatial-resolution drought information is essential for improving drought planning and preparedness. The objective of this study was to develop the concept of using satellite-based hybrid drought index called the Vegetation Drought Response Index in South Korea (VegDRI-SKorea) that could improve spatial resolution for monitoring local and regional drought. The VegDRI-SKorea was developed using the Classification And Regression Trees (CART) algorithm based on remote sensing data such as Normalized Difference Vegetation Index (NDVI) from MODIS satellite images, climate drought indices such as Self Calibrating Palmer Drought Severity Index (SC-PDSI) and Standardized Precipitation Index (SPI), and the biophysical data such as land cover, eco region, and soil available water capacity. A case study has been done for the 2012 drought to evaluate the VegDRI-SKorea model for South Korea. The VegDRI-SKorea represented the drought areas from the end of May and to the severe drought at the end of June. Results show that the integration of satellite imageries and various associated data allows us to get improved both spatially and temporally drought information using a data mining technique and get better understanding of drought condition. In addition, VegDRI-SKorea is expected to contribute to monitor the current drought condition for evaluating local and regional drought risk assessment and assisting drought-related decision making.

남기성 Nam Ki Sung , 성찬용 Sung Chan Yong

DOI: JKWST Vol.57(No.4) 11-19, 2015

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The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.

손영권 Son Yeong Kwon , 이한필 Rhee Han-pil , 김해도 Kim Haedo , 최선화 Choi Sun Wha , 김정대 Kim Jeong Dae

DOI: JKWST Vol.57(No.4) 21-29, 2015

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Safety of reclaimed wastewater irrigation needs to be evaluated to promote public health. Quantitative microbial and toxic risk assessment was conducted to identify the level of risk for farmland workers who use reclaimed wastewater and groundwater in Jeju island. Microbial risk through inhalation and ingestion exposure was below acceptable level (less than 10^-3) of 7.07×10^-6 for reclaimed wastewater and 9.99×10^-8 for groundwater irrigation worker. Aggregate exposure risk of Ni, As and Cu was most contributable to overall risk in both reclaimed wastewater and groundwater irrigation plot. High cumulative exposure risk was estimated through non-dietary soil ingestion and dermal contact of soil, due to the high concentration of As, Cu and Ni in farmland soil. Overall toxic risk was 2.68×10^-4 for reclaimed water and 2.39×10^-4 for groundwater irrigation, which could not meet acceptable toxic risk level of 10^-6. Further efforts, such as provide personal protective equipments or public health education, need to be implicated to reduce adverse health risk.

강구 Kang Ku , 박성직 Park Seong-jik

DOI: JKWST Vol.57(No.4) 31-38, 2015

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This study aims to assess the effectiveness of limestone, zeolite, and crushed concrete as capping material to block the release of heavy metals (As, Cu, Cr, Ni, and Pb) and reduce the sediment oxygen demand. The efficiency of limestone, zeolite, and crushed concrete was evaluated in a reactor in which a 1-cm thick layer of capping materials was placed on the sediments collected from Inchon north harbor. Dissolved oxygen concentration and heavy metal concentration in seawater above the uncapped sediments and capping material were monitored for 17 days. The sediment oxygen demand was in the following increasing order: crushed concrete (288.37 mg/m²·d) < zeolite (428.96 mg/m²·d) < limestone (904.53 mg/m²·d) < uncapped (981.34 mg/m²·d). The capping materials could reduce the sediment oxygen demand by blocking the release of biochemical matters consuming dissolved oxygen in seawater. It was also shown that zeolite and crushed concrete could effectively block the release of Cu, Ni, and Pb but those were not effective for the interruption of As and Cr release from marine contaminated sediments.

김솔희 Kim Solhee , 김태곤 Kim Taegon , 서교 Suh Kyo

DOI: JKWST Vol.57(No.4) 39-49, 2015

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Since most medical facilities and medical personnel are concentrated in urban areas in South Korea, an imbalance of access to medical facilities causes a gap in medical resource availability between urban and rural areas. Accessibility to medical facilities is a means of assessment that evaluates a measure of inequality in utilization of medical resources. The evaluation of accessibility uses Euclidean distance, in general; however, this method has its limits in that Euclidean distance cannot reflect actual distance. This study aims to estimate real road distance from village halls to medical facilities in rural areas using Open Application Programming Interface (Open API) of an internet portal site. Using real road distance, we evaluated medical accessibility and compared it with Euclidean distance. The accessibility to primary medical institutions was valued relatively well, but secondary and tertiary medical institutions were vulnerable in Pyeonchang-gun. Comparing Euclidean distance with real road distance from village halls to medical facilities, real road distance appeared to be approximately 1.4 times that of Euclidean distance. This calculation is similar to the circuity factor of Gangwon-do in Korea that estimated to fix the limits of Euclidean distance and assumed real road distance.

이수인 Lee Su In , 원철희 Won Chul Hee , 신민환 Shin Min Hwan , 신재영 Shin Jae Young , 전제홍 Jeon Je Hong , 최중대 Choi Joong Dae

DOI: JKWST Vol.57(No.4) 51-59, 2015

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Various Best Management Practices (BMPs) have been suggested to reduce soil erosion and non point source (NPS) pollutant loads from agricultural fields. However, very little research regarding water quality improvement with No-till (NT) has been performed in Korea. Thus, effects of NT were investigated in this study. The objective of the study was to investigate the effect of NT on the surface runoff and sediment discharge in a field. Eight experimental plots of 5×30 m in size and 3 % or 8 % in slope prepared on gravelly sandy loam soil were treated with Conventional-till (CT) and NT. Runoff and NPS pollution discharge were monitored and compared the treatments. The amounts of rainfall from 13 monitored events ranged from 28.7 mm to 503.5 mm. The runoff amount was reduced by 17.6~59.2 % in 3 % NT and 29.6~53.2 % in 8 % NT. The average NPS pollution loads of the 3 % NT plots and 8 % NT plot were reduced about 45.1~89.2 % and 47.7~98.0 % compared to those of the CT plots, respectively. This research revealed that NT can reduce the NPS pollution loads substantially as well as increase the crop yield. Runoff and NPS pollution loads reduction by NT method could be contribute to improve the water quality of streams in agricultural regions.

김묘정 Kim Myojeong , 김광섭 Kim Gwangseob , 이재응 Yi Jaeeung

DOI: JKWST Vol.57(No.4) 61-71, 2015

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Quantitative variability of AMSR2 (Advanced Microwave Scanning Radiometer 2) soil moisture data shows that the remotely sensed soil moisture is underestimated during Spring and Winter seasons and is overestimated during Summer and Fall seasons. Therefore the bias correction of the remotely sensed data is essential for the purpose of water resource management. To enhance their applicability, the bias of AMSR2 soil moisture data was corrected using ground observation data at Cheorwon Chuncheon, Suwon, Cheongju, Jeonju, and Jinju sites. Test statistics demonstrated that the correlation coefficient R is improved from 0.107~0.328 to 0.286~0.559 and RMSE is improved from 9.46~14.36 % to 5.38~9.62 %. Bias correction using ground network data improved the applicability of remotely sensed soil moisture data.

이재남 Lee Jaenam , 노재경 Noh Jaekyoung

DOI: JKWST Vol.57(No.4) 73-84, 2015

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An embankment raising project on 113 agricultural reservoirs in Korea was implemented in 2009 to increase water supply capacity for agricultural water and instream uses. This study evaluated the future water supply capacity of the Imgo reservoir at which the agricultural reservoir embankment raising project was completed, considering climate change scenarios. The height of the embankment of the reservoir was increased by 4.5 m, thereby increasing its total storage from 1,657.0 thousand to 3,179.5 thousand cubic meters. To simulate the reservoir water storage with respect to climate changes, two climate change scenarios, namely, RCP 4.5 and RCP 8.5 (in which greenhouse gas reduction policy was executed and not executed, respectively) were applied with bias correction for reflecting the climate characteristics of the target basin. The analysis result of the agricultural water supply capacity in the future, after the agricultural reservoir embankment raising project is implemented, revealed that the water supply reliability and the agricultural water supply increased, regardless of the climate change scenarios. By simulating the reservoir water storage considering the instream flow post completion of the embankment raising project, it was found that water shortage in the reservoir in the future is not likely to occur when it is supplied with an appropriate instream flow. The range of instream flow tends to decrease over time under RCP 8.5, in which the greenhouse gas reduction policy was not executed, and the restoration of reservoir storage was lower in this scenario than in RCP 4.5, in which greenhouse gas reduction policy was executed.

이충원 Lee Chung-won , 박성용 Park Sung-yong , 오현문 Oh Hyeon-mun , 김용성 Kim Yong-seong

DOI: JKWST Vol.57(No.4) 85-99, 2015

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It is urgent to redevelop the superannuated reservoir levee through the levee raising for countermeasure to climate change and improvement of storage capacity of reservoir. However, low compaction degree of the raised reservoir levee owing to poor construction condition leads to degradation of the stability of the reservoir levee on seepage and earthquake. In this study, seepage and seismic behavior of raised reservoir levee with low compaction degree was evaluated through numerical simulation. From the simulated results, water level raising possibly induces crack and/or sinkhole on the surface of the poorly-compacted raised reservoir levee owing to the increase of the subsidences at the crown and the front side of that. In addition, relatively larger displacement and acceleration response at the front side of raised reservoir levee in seismic condition may degrade overall stability of reservoir levee. Therefore, reasonable construction management for the compaction of the raised reservoir levee is required for ensuring long-term stability on seepage and earthquake.

신민환 Shin Min Hwan , 이수인 Lee Su In , 장정렬 Jang Jeong Ryeol , 신재영 Shin Jae Young , 박윤식 Park Youn Shik , 임경재 Lim Kyoung Jae , 최중대 Choi Joong Dae

DOI: JKWST Vol.57(No.4) 101-112, 2015

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This study was conducted to predict greenhouse gas (GHG) emission from a radish field by future climate change scenario. A radish field located at Chuncheon-si Gangwon-do was selected, and A1B Special Report on Emission Scenario (SRES) of the IPCC (Intergovernmental panel on climate change) was applied to simulate the future potential climate change. Rainfall and temperature data were predicted to be increased by 8.4 % and 1.9 % in 2040s, 35.9 % and 27.0 % in 2060s, 19.2 % and 30.8 % in 2090s, respectively, compared to the climate data in 2010s. The N₂O, CO₂, and CH₄ emission were estimated to be increased by 0.4 up to 2.4 kg/ha/yr, by 500.5 up to 734.5 kg/ha/year, and by 29.4 up to 160.4 kg/ha/yr, which were resulted from the global warming potential (GWP) of 14.5~21.7 CO₂/ha/year caused by the amount changes of rainfall, temperature, manure amendment, and fertilizer applied in fields. One distinct feature of the study result was that the changes of N₂O-N, CH₄-C and CO₂-C with future potential climate change simulation were varied by soil texture. Therefore it was concluded that there is a need to apply appropriate amount of manure amendment needs and to consider soil texture as well.