표준강수증발산지수를 활용한 미래 가뭄특성의 시계열 변화전망

남원호,Michael J. Hayes,Donald A. Wilhite,Mark D. Svoboda 한국농공학회 2015 한국농공학회논문집 Vol.57 No.1

Recent droughts in South Korea have had large economic and environmental impacts across the country. Changes in rainfall and hydrologic patterns dueto climate change can potentially increase the occurrence of extreme droughts and affect the future availability of water resources. Therefore, it isnecessary to evaluate drought vulnerability for water resources planning and management, and identify the appropriate mitigation actions to conduct adrought risk analysis in the context of climate change. The objective of this study is changes in the temporal trends of drought characteristics in SouthKorea to examine drought impacts under climate change. First, the changes of drought occurrence were analyzed by applying the StandardizedPrecipitation Evapotranspiration Index (SPEI) for meteorological data on 54 meteorological stations, and were analyzed for the past 30 years(1981-2010), and Representative Concentration Pathways (RCP) climate change scenarios (2011-2100). Second, the changes on the temporal trends ofdrought characteristics were performed using run theory, which was used to compare drought duration, severity, and magnitude to allow for quantitativeevaluations under past and future climate conditions. These results show the high influence of climate change on drought phenomenon, and will contributeto water resources management and drought countermeasures to climate change.

가뭄대응 의사결정을 위한 공공참여 및 아웃리치 프로그램: 가뭄 토너먼트

남원호,( Michael J. Hayes ),( Nicole Wall ),윤동현 한국농공학회 2017 韓國農工學會誌 : 전원과 자원 Vol.59 No.1

기후변화대응을 위한 국립가뭄경감센터의 가뭄관리 및 정책방안

남원호 ( Nam Won-ho ),( Michael J Hayes ),( Donald A Wilhite ),( Tsegaye Tadesse ),( Mark D Svoboda ),( Cody L Knutson ) 한국농공학회 2014 韓國農工學會誌 : 전원과 자원 Vol.56 No.2

표준강수증발산지수를 활용한 미래 가뭄특성의 시계열 변화전망

Nam, Won-Ho,Hayes, Michael J.,Wilhite, Donald A.,Svoboda, Mark D. 한국농공학회 2015 한국농공학회논문집 Vol.57 No.1

Recent droughts in South Korea have had large economic and environmental impacts across the country. Changes in rainfall and hydrologic patterns due to climate change can potentially increase the occurrence of extreme droughts and affect the future availability of water resources. Therefore, it is necessary to evaluate drought vulnerability for water resources planning and management, and identify the appropriate mitigation actions to conduct a drought risk analysis in the context of climate change. The objective of this study is changes in the temporal trends of drought characteristics in South Korea to examine drought impacts under climate change. First, the changes of drought occurrence were analyzed by applying the Standardized Precipitation Evapotranspiration Index (SPEI) for meteorological data on 54 meteorological stations, and were analyzed for the past 30 years (1981-2010), and Representative Concentration Pathways (RCP) climate change scenarios (2011-2100). Second, the changes on the temporal trends of drought characteristics were performed using run theory, which was used to compare drought duration, severity, and magnitude to allow for quantitative evaluations under past and future climate conditions. These results show the high influence of climate change on drought phenomenon, and will contribute to water resources management and drought countermeasures to climate change.

관개취약성 평가모형 및 군집분석을 활용한 용수공급 위험도 평가

남원호,김태곤,홍은미,Michael J. Hayes,Mark D. Svoboda 한국농공학회 2015 한국농공학회논문집 Vol.57 No.1

Because reservoirs that supply irrigation water play an important role in water resource management, it is necessary to evaluate the vulnerability of thisparticular water supply resource. The purpose of this study is to provide water supply risk maps of agricultural reservoirs in South Korea using irrigationvulnerability model and cluster analysis. To quantify water supply risk, irrigation vulnerability indices are estimated to evaluate the performance of thewater supply on the agricultural reservoir system using a probability theory and reliability analysis. First, the irrigation vulnerability probabilities of 1,346reservoirs managed by Korea Rural Community Corporation (KRC) were analyzed using meteorological data on 54 meteorological stations over the past30 years (1981-2010). Second, using the K-mean method of non-hierarchical cluster analysis and pre-simulation approach, cluster analysis was appliedto classify into three groups for characterizing irrigation vulnerability in reservoirs. The morphology index, watershed area, irrigated area, and ratiobetween watershed and irrigated area are selected as the clustering analysis parameters. It is suggested that the water supply risk map be utilized as a basisfor the establishment of risk management measures, and could provide effective information for a reasonable decision making on drought risk mitigation.

위성기반 Climate Hazards Group InfraRed Precipitation with Station (CHIRPS)를 활용한한반도 지역의 기상학적 가뭄지수 적용

문영식,남원호,전민기,김태곤,홍은미,Michael J. Hayes,Tsegaye Tadesse 한국농공학회 2019 한국농공학회논문집 Vol.61 No.2

Remote sensing products have long been used to monitor and forecast natural disasters. Satellite-derived rainfall products are becoming more accurateas space and time resolution improve, and are widely used in areas where measurement is difficult because of the periodic accumulation of imagesin large areas. In the case of North Korea, there is a limit to the estimation of precipitation for unmeasured areas due to the limited accessibility andquality of statistical data. CHIRPS (Climate Hazards Group InfraRed Precipitation with Stations) is global satellite-derived rainfall data of 0.05 degreegrid resolution. It has been available since 1981 from USAID (U.S. Agency for International Development), NASA (National Aeronautics and SpaceAdministration), NOAA (National Oceanic and Atmospheric Administration). This study evaluates the applicability of CHIRPS rainfall products forSouth Korea and North Korea by comparing CHIRPS data with ground observation data, and analyzing temporal and spatial drought trends using theStandardized Precipitation Index (SPI), a meteorological drought index available through CHIRPS. The results indicate that the data set performed wellin assessing drought years (1994, 2000, 2015 and 2017). Overall, this study concludes that CHIRPS is a valuable tool for using data to estimateprecipitation and drought monitoring in Korea.

Developing the vegetation drought response index for South Korea (VegDRI-SKorea) to assess the vegetation condition during drought events

Nam, Won-Ho,Tadesse, Tsegaye,Wardlow, Brian D.,Hayes, Michael J.,Svoboda, Mark D.,Hong, Eun-Mi,Pachepsky, Yakov A.,Jang, Min-Won TaylorFrancis 2018 International journal of remote sensing Vol.39 No.5

<P>South Korea has experienced severe droughts and water scarcity problems that have influenced agriculture, food prices, and crop production in recent years. Traditionally, climate-based drought indices using point-based meteorological observations have been used to help quantify drought impacts on the vegetation in South Korea. However, these approaches have a limited spatial precision when mapping detailed vegetation stress caused by drought. For these reasons, the development of a drought index that provides detailed spatial-resolution information on drought-affected vegetation conditions is essential to improve the country's drought monitoring capabilities, which are needed to help develop more effective adaptation and mitigation strategies. The objective of this study was to develop a satellite-based hybrid drought index called the vegetation drought response index for South Korea (VegDRI-SKorea) that could improve the spatial resolution of agricultural drought monitoring on a national scale. The VegDRI-SKorea was developed for South Korea, modifying the original VegDRI methodology (developed for the USA) by tailoring it to the available local data resources. The VegDRI-SKorea utilizes a classification and regression tree (CART) modelling approach that collectively analyses remote-sensing data (e.g. normalized difference vegetation index (NDVI)), climate-based drought indices (e.g. self-calibrated Palmer drought severity index (PDSI) and standardized precipitation index (SPI)), and biophysical variables (e.g. elevation and land cover) that influence the drought-related vegetation stress. This study evaluates the performance of the recently developed VegDRI-SKorea for severe and extreme drought events that occurred in South Korea in 2001, 2008, and 2012. The results demonstrated that the hybrid drought index improved the more spatially detailed drought patterns compared to the station-based drought indices and resulted in a better understanding of drought impacts on the vegetation conditions. The VegDRI-SKorea model is expected to contribute to the monitoring of drought conditions nationally. In addition, it will provide the necessary information on the spatial variations of those conditions to evaluate local and regional drought risk assessment across South Korea and assist local decision-makers in drought risk management.</P>

관개취약성 평가모형 및 군집분석을 활용한 용수공급 위험도 평가

Nam, Won-Ho,Kim, Taegon,Hong, Eun-Mi,Hayes, Michael J.,Svoboda, Mark D. 한국농공학회 2015 한국농공학회논문집 Vol.57 No.1

Because reservoirs that supply irrigation water play an important role in water resource management, it is necessary to evaluate the vulnerability of this particular water supply resource. The purpose of this study is to provide water supply risk maps of agricultural reservoirs in South Korea using irrigation vulnerability model and cluster analysis. To quantify water supply risk, irrigation vulnerability indices are estimated to evaluate the performance of the water supply on the agricultural reservoir system using a probability theory and reliability analysis. First, the irrigation vulnerability probabilities of 1,346 reservoirs managed by Korea Rural Community Corporation (KRC) were analyzed using meteorological data on 54 meteorological stations over the past 30 years (1981-2010). Second, using the K-mean method of non-hierarchical cluster analysis and pre-simulation approach, cluster analysis was applied to classify into three groups for characterizing irrigation vulnerability in reservoirs. The morphology index, watershed area, irrigated area, and ratio between watershed and irrigated area are selected as the clustering analysis parameters. It is suggested that the water supply risk map be utilized as a basis for the establishment of risk management measures, and could provide effective information for a reasonable decision making on drought risk mitigation.

CMIP5 기후모델 및 RCP 8.5 시나리오에 따른 동아시아 미래가뭄 전망

남원호 ( Won-ho Nam ),( Song Feng ),허창회 ( Chang-hoi Ho ),( Michael J. Hayes ),( Mark D. Svoboda ),김태곤 ( Taegon Kim ),홍은미 ( Eun-mi Hong ) 한국농공학회 2017 한국농공학회 학술대회초록집 Vol.2017 No.-

최근 전 지구적인 기상 이변으로 기상재해의 빈도 및 강도가 증가하고 있다. 미국에서는 1930년대 대가뭄(Megadrought) 이래 2012년부터 2017년까지 현재까지 미국 서부지역인 캘리포니아 지역에서 극심한 가뭄이 지속되었으며, 특히 2014 년은 1895 년 이후 최저 강수량을 기록하였다. 미국해양기상청 (National Oceanic and Atmospheric Administration, NOAA)이 발표하는 재해유형별 경제손실액 보고서에 의하면 가뭄에 의한 경제적 손실은 홍수에 비해 2배 이상이며, 1980년 이후 가뭄의 발생빈도는 전체 재해빈도 중 14%에 해당하지만 그 피해액은 전체 재해피해액 25%를 차지하고 있다. 국지적으로 발생한 가뭄으로 인해 미 전역에서 가뭄 피해를 입기 때문에, 대외무역에 의존하는 우리나라는 국내 가뭄전망과 더불어 인접한 동아시아 전역의 가뭄전망을 함께 살펴볼 필요가 있다. 본 연구에서는 기후변화에 관한 정부 간 협의체 (Intergovernmental Panel on Climate Change, IPCC)에서 제공하는 대표농도경로 시나리오 (Representative Concentration Pathways, RCPs)를 사용하여 동북아시아지역 5개 국가(한국, 북한, 중국, 일본, 몽골) 및 동남아시아지역 11개 국가 (인도네시아, 라오스, 말레이시아, 미얀마, 필리핀, 태국, 베트남 등)의 표준강수증발산지수(Standardized Precipitation Evapotranspiration Index, SPEI)를 산정하여 미래가뭄전망을 분석하였다.

Optical stimulation of cardiac cells with a polymer-supported silicon nanowire matrix

Parameswaran, Ramya,Koehler, Kelliann,Rotenberg, Menahem Y.,Burke, Michael J.,Kim, Jungkil,Jeong, Kwang-Yong,Hissa, Barbara,Paul, Michael D.,Moreno, Kiela,Sarma, Nivedina,Hayes, Thomas,Sudzilovsky, Ed National Academy of Sciences 2019 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.116 No.2

<P><B>Significance</B></P><P>Cardiac conduction disorders are potentially fatal illnesses caused by abnormalities in the heart’s electrical conduction system. Current treatments for these disorders, such as pacemakers, are effective but are bulky, rigid, and invasive. Here we develop a method to optically modulate cardiac beating frequency in primary cultured cardiomyocytes and adult rat hearts ex vivo, to a specified target frequency. Specifically, we use a low-irradiance moving laser stimulus and a biocompatible polymer–silicon nanowire composite material to achieve this modulation. This work has implications for future bioelectric studies of the cardiac conduction system as well as therapeutics for cardiac conduction disorders in the clinic.</P><P>Electronic pacemakers can treat electrical conduction disorders in hearts; however, they are invasive, bulky, and linked to increased incidence of infection at the tissue–device interface. Thus, researchers have looked to other more biocompatible methods for cardiac pacing or resynchronization, such as femtosecond infrared light pulsing, optogenetics, and polymer-based cardiac patches integrated with metal electrodes. Here we develop a biocompatible nongenetic approach for the optical modulation of cardiac cells and tissues. We demonstrate that a polymer–silicon nanowire composite mesh can be used to convert fast moving, low-radiance optical inputs into stimulatory signals in target cardiac cells. Our method allows for the stimulation of the cultured cardiomyocytes or ex vivo heart to beat at a higher target frequency.</P>