• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.2
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• pp.135-143
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• 2020

Natural drought is a three-dimensional phenomenon that simultaneously evolves in time and space. To evaluate the link between meteorological and hydrological droughts, we defined a drought event from a three-dimensional perspective and analyzed the propagation characteristics in time and spaces. Overall results indicated that 77 % of the total cases of spatio-temporal droughts was propagated based on the single category relationship between meteorological and hydrological drought events, while 23 % was affected by multiple meteorological drought events to the occurrence of hydrological drougts. Especially, it turned out that the hydrological drought was caused by the spatio-temporal effects of the propagation of four meteorological drought events generated due to long-term lack of precipitation in 1994-1995. In addition, the meteorological drought caused by the lack of precipitation in the summer of 2001 lasted for several months, and was propagated to the hydrological drought in April 2002.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.308-308
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• 2022

가뭄은 지구 대기 형성만큼이나 오래된 현상으로 생태계, 수문학, 농업 및 경제에 중대한 영향을 주며 세계 어디에서나 발생할 수 있는 자연재해 중 하나이다. 가뭄에 의한 사회·경제적 피해를 줄이고 가뭄 위험을 관리하기 위해서는 가뭄의 시공간적 특성을 이해하는 것이 중요하다. 하지만, 기존의 가뭄 감시는 가뭄 지표를 계산하여 산정된 결과 값을 바탕으로 해당 지역의 가뭄 유무의 정보를 제공하는 1차원적 방법으로 가뭄 감시 및 관리를 위해서는 시·공간적 정보제공이 필요하다. 본 연구에서는 시·공간적 가뭄 전이 분석을 위해 GPM(Global Precipitation Measurement) 자료를 활용하여 2000년부터 2020년까지 표준강수지수(Standardized Precipitation Index, SPI)를 산정하였으며, 산정된 SPI를 Spatial drought tracking (S-TRACK) 방법을 적용하여 가뭄의 대륙규모(continetal scale) 시공간적 변화와 전이현상을 살펴보고자 하였다. 본 연구를 결과를 바탕으로 가뭄의 시·공간적 변화에 대한 이해 및 광역규모에서의 가뭄현상의 이동과정을 알아볼 수 있으며, 더 나아가 본 연구의 성과는 기존의 국지적 가뭄 감시 및 예측 방법에 적용하여 가뭄에 대한 효율적인 대응방안을 마련하는 기초자료로 활용될 수 있을 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.111-111
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• 2020

하천환경과 기후의 변화로 인해 수질오염 과정의 메커니즘이 더욱 복잡해짐에 따라 다양한 요인을 고려한 불확실성 평가 연구가 요구되고 있다. 하천 수질 중에서도 부영양화 문제는 특히 개발로 인한 하천환경 변화 이후 사회 정치적 논점이 되어왔다. 본 연구에서는 지난 7년 동안의 수질 변화의 전반적인 양상을 조사하였으며, 클로로필-a(Chl-a, chlorophyll-a) 농도의 시공간적 의존성의 효과적으로 고려하기 위해 기계학습 기반 분류(classification) 접근법인 다변량 은닉 마코프 모형(MHMM, multivariate hidden Markov model)을 사용하였다. 월 단위 수질 및 수문 자료를 사용하여 Chl-a의 변동성을 군집화하여 수질 상태의 익월 천이확률을 효과적으로 추정하였다. Chl-a와 수질 및 수문기상 조건의 관계를 평가하였으며, 결과적으로 수질 상태의 시공간적 전이가 정확하게 식별되었고 이의 잠재적 원인에 대하여 논의하였다.

• Journal of Korea Water Resources Association
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• v.43 no.7
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• pp.667-679
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• 2010

The distributed hydrologic model has been considerably improved due to rapid development of computer hardware technology as well as the increased accessibility and the applicability of hydro-geologic information using GIS. It has been acknowledged that physically-based distributed hydrologic model require significant amounts of data for their calibration, so its application at ungauged catchments is very limited. In this regard, this study was intended to develop a distributed hydrologic model (S-RAT) that is mainly based on conceptually grid-based water balance model. The proposed model shows advantages as a new distributed rainfall-runoff model in terms of their simplicity and model performance. Another advantage of the proposed model is to effectively assess spatio-temporal variation for the entire runoff process. In addition, S-RAT does not rely on any commercial GIS pre-processing tools because a built-in GIS pre-processing module was developed and included in the model. Through the application to the two pilot basins, it was found that S-RAT model has temporal and spatial transferability of parameters and also S-RAT model can be effectively used as a radar data-driven rainfall-runoff model.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.46-46
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• 2023

돌발가뭄 (Flash drought)은 일반적인 가뭄과 달리 기후변화에 따른 기상 이상으로 인해 단기간 급속하게 발생하는 가뭄이다. 짧은 기간에 식생 스트레스가 증가하며, 작물생산량의 감소로 인해 농업 생태계에 피해를 야기하며, 과도한 증발 수요 및 급격한 토양수분의 감소는 수문학적 영향을 미치게 된다. 본 연구에서는 최근 개발된 Flash Drought Intenisty Index (FDII, 2021)를 활용하여 2014년부터 2018년까지 5년간 발생한 돌발가뭄에 분석하였다. FDII는 가뭄 심화속도, 평균 심각도의 두 가지 요소를 곱하여 나타내며, 일반적으로 가뭄 및 비가뭄에 대한 정도를 나타내는 아노말리 (Anomaly) 대신 백분위수 (Percentile)를 활용한다. 국내 돌발가뭄 분석을 위하여 Gravity Recovery and Climate Experiment (GRACE) 위성영상 기반 근역층 토양수분 자료를 활용하였다. 2014년부터 2018년까지 전국 8도 (경기, 강원, 충남, 충북, 전남, 전북, 경남, 경북)를 대상으로 돌발가뭄 사상에 대하여 토양수분 백분위수의 월별 공간분포 및 FDII를 산정하여 국내 돌발가뭄의 강도를 정량화하였다. 지역 및 시기별로 다르게 발생하는 돌발가뭄을 대상으로 FDII를 활용하여 돌발가뭄의 초기 발생, 가뭄 전이 현상 등 시공간적 특성을 분석하고자 한다. 향후 대상 지역의 세분화 및 장기적인 관점에서의 FDII 적용으로 신뢰성 높은 국내 돌발가뭄 모니터링 및 분석 기술로 활용할 수 있을 것으로 기대된다.

• Journal of Korea Water Resources Association
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• v.45 no.10
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• pp.1069-1079
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• 2012

In this study, to analyze travelling route and transition characteristics which is a spatial time interpretation method now actively progressed in domestic as well as abroad, it was intended to develop new drought interpretation technique which can decide the centroid and orbit of drought through assuming ellipse using Mass Moment concept. First of all, after estimating Standard Precipitation Index (SPI) per different precipitation observatory station to extract drought events, by selecting precipitation sites where drought starting and end point are same, these were categorized as CASE. As a results, with various CASE selections falling in specific duration for monthly drought analysis, it is possible to find out drought area that additionally occurred, and drought reliving process could be confirmed more definitely. Therefore, if the research methods adopted in this study for drought monitoring are utilized, not only accurate spatio-temporal drought analysis is possible, also pattern of drought centroid movement can be analyzed by establishing statistically significant spatial characteristics data after separating all the drought events that occurred sporadically in Korea Peninsula.

• Informatization Policy
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• v.26 no.4
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• pp.36-61
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• 2019

While smart devices can have a positive impact on work efficiency and productivity by reducing time-space constraints and enabling rapid processing of tasks, side effects can arise from the imbalances between work and personal life. In recent years, as smart devices are increasingly used in work environments, it is more necessary than ever to understand the related phenomenon, find the cause of negative effects, and search for appropriate solutions. This study has developed and verified a theoretical model that shows how the technical characteristics known as the utility of smart devices are converted into negative results such as work-life conflict. As a result of analyzing the collected data from the employees, our study provides significant implications for the researchers, as well as the practitioners and policy makers, regarding various relationships among IT-enabled work flexibility, after-hours work connectivity and work-life conflict, and the new knowledge about the important role of segmentation supplies from the organization.

• Archives of design research
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• v.13 no.1
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• pp.121-130
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• 2000

This study can be expressed by gathered and formed into the exhibition space's structure practical progress/ application. For the one model of fascinating exhibition's space thru inter-space's pertinent adjustment, production between spactator and exhibition constituent on an exhibition story-line, I adjusted the focus to follow mentioned methods systematically for the example; An exhibition space is completed to be very impressive and attractive space by proper adjustment and production of M-M/C interface in exhibition storyline. Quantity space is transfered into quality space through the transmission of an exhibition which can be define as the point of an exhibition structure. And also could de transferd into a bodily sensation space that inherent full of interactive constituent. Changeable exhibition constituents (exhibition item and text) that sporadically expatiated (not trimed, the original form) in the process of an exhibition structure draw much higer quality of the optimal solution in optimize process which is given when aggregate again to contextual flow of synthetic exhibition scenario. Reconstruction of individual exhibition constituents to the new story, that is, transference of exhibition text to exhibition context is inspirit to an exhibition by maximize the exhibition effect in connection can be systematized through carrying out an outcentripetalpart. However, since pattern of an exhibition structure that consequtively meet variety spacetime of an exhibittion environmental can't be exist, this study presents centralizing the exhibition plan of Korea communication pavilion of the annual Expo Comm Wireress Korea, sustained process from design proposal, research and analysis to synthesis, development, transmission and management to an example of an applying crystallization.

• Journal of Soil and Groundwater Environment
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• v.12 no.3
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• pp.75-80
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• 2007

This study evaluated groundwater quality around an uncontrolled landfill in W sity, Korea, which was monitored for about two years (2005-2006). Parameters of concern include redox-sensitive indicators such as pH, DO, EC, ORP, DOC (dissolved organic carbon), NH3, NO3 and SO4. About 10 years have elapsed after closing dumping of municipal wastes in the landfill. Leachates showed widely varying concentrations in COD(136${\sim}$263 mg/L), T-N(121${\sim}$186 mg/L), and NH3-N(14${\sim}$369 mg/L). Groundwater at the immediate downgradient of the landfill showed weakly acidic pH condition but very high levels of EC (3,000-4,000 ${\mu}S/cm$), which indicated that the groundwater was largely affected by the landfill leachate. Cl, a conservative ion, showed over 200 mg/L at the landfill border, but a gradually decreasing level with distance from the landfill, representing dispersion and dilution (natural attenuation) due to mixing with surrounding groundwater and replenished rainwater. Redox potential showed negative value at the landfill border but it increased up to 350 mV at downgradient wells, which indicated conversion of redox condition from reducing oxic ones. Ammonia, was largely enriched at most of the monitoring wells and its level greatly exceeded drinking water standard. In summary, all the parameters evidenced occurrence of natural attenuation with distance and with time but further monitoring is still required.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.246-260
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• 2014

A 90-m horizontal-resolution numerical model was configured to study the micrometeorological features of local winds in the valley of Gwangneung KoFlux (Korea Flux network) Sites (GDK: Gwangneung Deciduous forest site in Korea, GCK: Gwangneung Coniferous forest site in Korea) during summer days. The U. S. Geological Survey (USGS) Shuttle Radar Topography Mission (SRTM) data were employed for high-resolution model terrain height. Model performance was evaluated by comparing observed and simulated near-surface temperature and winds. Detailed qualitative analysis of the model-simulated wind field was carried out for two selected cases which are a clear day (Case I) and a cloudy day (Case II). Observed winds exhibited that GDK and GCK, as well as Case I and Case II, had differences in timing, duration and strength of daytime and nighttime wind direction and speeds. The model simulation results strongly supported the existence of the drainage flow in the valley of the KoFlux tower sites. Overall, the simulated model fields realistically presented the diurnal cycle of local winds in and around the valley, including the morning drainage-upslope transition and the evening reversal of upslope wind. Also, they indicated the complexity of local winds interactions by presenting that daytime westerly winds in the valley were not always pure mountain winds and were often coupled with larger-scale wind systems, such as synoptic-scale winds or mesoscale sea breezes blowing from the west coast of the peninsula.