• The Journal of Engineering Geology
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• v.33 no.3
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• pp.489-502
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• 2023

Urban floods pose significant challenges to cities worldwide, driven by the interplay between urbanization and climate change. This review examines recent studies of urban floods to understand their causes, impacts, and potential mitigation strategies. Urbanization, with its increase in impermeable surfaces and altered drainage patterns, disrupts natural water flow, exacerbating surface runoff during intense rainfall events. The impacts of urban floods are far-reaching, affecting lives, infrastructure, the economy, and the environment. Loss of life, property damage, disruptions to critical services, and environmental consequences underscore the urgency of effective urban flood management. To mitigate urban floods, integrated flood management strategies are crucial. Sustainable urban planning, green infrastructure, and improved drainage systems play pivotal roles in reducing flood vulnerabilities. Early warning systems, emergency response planning, and community engagement are essential components of flood preparedness and resilience. Looking to the future, climate change projections indicate increased flood risks, necessitating resilience and adaptation measures. Advances in research, data collection, and modeling techniques will enable more accurate flood predictions, thus guiding decision-making. In conclusion, urban flooding demands urgent attention and comprehensive strategies to protect lives, infrastructure, and the economy.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.398-398
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• 2020

대도시 상류부에 위치한 댐의 과도한 방류 또는 급작스러운 붕괴는 대규모의 인명 또는 재산피해를 야기할 수 있으며, 다양한 댐 유입량 조건에 따른 침수양상을 파악하는 것은 수재해 대응능력 향상에 필수적이다. 그러나 다양한 과다한 댐 방류 또는 붕괴유량에 따른 침수 범위는 도시의 내수침수와 달리 매우 넓은 지형조건을 고려하며 침수 범위가 광범위하게 나타날 수 있다. 이는 다양한 댐 유입량 조건에 따른 침수 지도를 생성 및 파악하는데 어려움을 가중시키며, 특히 댐 운영에 따른 침수양상을 실시간으로 파악하는데 어려움을 가중시킨다. 본 연구에서는 저빈도부터 PMF(Probable Maximum Flood) 조건까지의 다양한 댐 유입량자료를 바탕으로, 1차원 하천홍수해석을 실시하였다. 연구 대상으로 팔당댐에 대한 댐 해석을 실시하였으며, 팔당댐 하류에 위치한 서울시에 대한 영향을 분석하였다. 1차원 해석 결과로 산정되는 각하도 단면 별 홍수위자료와 GIS을 연계하여 다양한 발생빈도를 나타내는 유입량에 대한 침수지도를 생성하였으며, 기존에 제시된 발생빈도에 따른 침수지도 외에 임의 빈도의 침수지도를 실시간으로 생성할 수 있는 랜덤포레스트 회귀 모형을 구축하였다. 위의 과정들을 통해 다양한 유입량 조건에 따른 연구대상 지역에서의 침수예상도를 분석할 수 있었으며, 서울시 전반적으로 나타날 수 있는 침수심의 공간적 분포를 파악할 수 있었다. 주어진 침수 지도를 이용하여 서울시에 대한 인구 및 건축물의 경제적 가치 자료를 이용하여 추가적인 홍수 위험도 분석이 가능할 것으로 보이며, 임의 빈도에 대하여 실시간으로 침수를 예측할 수 있는 랜덤포레스트와 연계할 수 있다. 제시된 방법론은 댐의 과다한 방류량과 붕괴 현상을 재현하며, 도시의 수재해 대응능력 향상을 위한 기초자료를 제공할 수 있을 것으로 보인다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.155-162
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• 2009

Univariate frequency analyses are widely used in practical hydrologic design. However, a storm event is usually characterized by amount, intensity, and duration of the storm. To fully understand these characteristics and to use them appropriately in hydrologic design, a multivariate statistical approach is necessary. This study applied a Gumbel mixed model to a bivariate storm frequency analysis using hourly rainfall data collected for 46 years at the Seoul rainfall gauge station in Korea. This study estimated bivariate return periods of a storm such as joint return periods and conditional return periods based on the estimation of joint cumulative distribution functions of storm characteristics. These information on statistical behaviors of a storm can be of great usefulness in the analysis and assessment of the risk associated with hydrologic design problems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2D
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• pp.191-198
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• 2010

The displacement of slope is a key factor in predicting the risk of a landslide. Therefore, the slope displacement should be continuously observed with high accuracy. Recently, high-tech equipment such as optical fiber sensor, GPS, total station and measuring instrument have been used. However, such equipment is poorly used in fields due to economics, environment, convenience and management. Because of this, development of substantial observational techniques for varied slope observation and field applications is needed. This study analyzed the possibility of terrestrial LiDAR for slope monitoring and suggested it as information-obtaining technique for slope investigation and management. For that, this study evaluated the monitoring accuracy of terrestrial LiDAR and performed GRID analysis to read the displacement area with the naked eye. In addition, it suggested a methodology for slope monitoring.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.12 no.4
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• pp.145-157
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• 2017

SMEs play an important role in the domestic economy. Regarding competency to respond flexibly to unpredictable changes, agility of SMEs is more emphasized. Entrepreneurship orientation is an important factor in the source of SMEs that enable such competency. Entrepreneurial orientation refers to the tendency of a CEO or a member of a corporation to be innovative, risk-taking, and active in the face of various market opportunities. In other words, it refers to the tendency to be expressed in the activities of the entire company without regard to specific technologies or industries. Entrepreneurial orientation has a direct or indirect effect on business performance. Therefore, in this study, we conducted theoretical and empirical studies on the effect of entrepreneurial orientation of SME managers on business performance. Research hypotheses were derived through theoretical research. We focused on the mediating effect of innovation activity and tried to identify the mechanism that entrepreneurial orientation leads to business performance through product innovation and service innovation activity. We investigated whether innovativeness, proactiveness, and risk-taking, which are sub-variables of entrepreneurial orientation, affect business performance through product innovation and service innovation. We conducted a survey of SMEs in Busan and Kyungnam regions to examine the research hypotheses. The results show that product innovation and service innovation have mediating effects. The results of the study are as follows. Product innovation has mediating effect of innovativeness and risk-taking on business performance. Service innovation has been found to mediate innovativeness, proactiveness, and risk-taking on business performance. There was a difference in the mediation effect between the two innovations. Product innovation showed a low mediating effect and a large direct effect. On the other hands, service innovation is relatively more mediating than product innovation. The implications of the research results are derived in relation to the essential differences between product innovation and service innovation. Limitations of the study and directions for future research are presented.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.55-64
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• 2019

The flowering seasons can be advanced due to climate change that would cause an abnormally warm winter. Such warm winter would increase the frequency of crop damages resulted from sudden occurrences of low temperature before and after the vegetative growth stages, e.g., the period from germination to flowering. The degree and pattern of freezing damage would differ by the development stage of each individual fruit tree even in an orchard. A critical temperature, e.g., killing temperature, has been used to predict freeze damage by low-temperature conditions under the assumption that such damage would be associated with the development stage of a fruit flower bud. However, it would be challenging to apply the critical temperature to a region where spatial variation in temperature would be considerably high. In the present study, a phenological model was used to estimate major bud development stages, which would be useful for prediction of regional risks for the freeze damages. We also derived a linear function to calculate a probabilistic freeze risk in spring, which can quantitatively evaluate the risk level based solely on forecasted weather data. We calculated the dates of freeze damage occurrences and spatial risk distribution according to main production areas by applying the spring freeze risk function to apple, peach, and pear crops in 2018. It was predicted that the most extensive low-temperature associated freeze damage could have occurred on April 8. It was also found that the risk function was useful to identify the main production areas where the greatest damage to a given crop could occur. These results suggest that the freezing damage associated with the occurrence of low-temperature events could decrease providing early warning for growers to respond abnormal weather conditions for their farm.

• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.981-992
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• 2023

Due to recent global climate change, the scale of flood damage is increasing as rainfall is concentrated and its intensity increases. Rain on a scale that has not been observed in the past may fall, and long-term rainy seasons that have not been recorded may occur. These damages are also concentrated in ASEAN countries, and many people in ASEAN countries are affected, along with frequent occurrences of flooding due to typhoons and torrential rains. In particular, the Bandung region which is located in the Upper Chitarum River basin in Indonesia has topographical characteristics in the form of a basin, making it very vulnerable to flooding. Accordingly, through the Official Development Assistance (ODA), a flood forecasting and warning system was established for the Upper Citarium River basin in 2017 and is currently in operation. Nevertheless, the Upper Citarium River basin is still exposed to the risk of human and property damage in the event of a flood, so efforts to reduce damage through fast and accurate flood forecasting are continuously needed. Therefore, in this study an artificial intelligence-based river flood water level forecasting model for Dayeu Kolot as a target station was developed by using 10-minute hydrological data from 4 rainfall stations and 1 water level station. Using 10-minute hydrological observation data from 6 stations from January 2017 to January 2021, learning, verification, and testing were performed for lead time such as 0.5, 1, 2, 3, 4, 5 and 6 hour and LSTM was applied as an artificial intelligence algorithm. As a result of the study, good results were shown in model fit and error for all lead times, and as a result of reviewing the prediction accuracy according to the learning dataset conditions, it is expected to be used to build an efficient artificial intelligence-based model as it secures prediction accuracy similar to that of using all observation stations even when there are few reference stations.

• Sleep Medicine and Psychophysiology
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• v.16 no.2
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• pp.85-90
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• 2009

Introduction: There has been an increasing interest in the relationship between sleep and suicidality. In addition, suicidal patients habitually report their sleep problems. Although sleep-related complaints and electroencephalographic changes are generally encountered in psychiatric disorders, sleep complaints such as insomnia, hypersomnia and nightmares are more common in suicidal patients. In current study, we aimed at investigating the relationship between self-reported sleep duration and suicidality in general population. Methods: One thousand general population (male:female=500:500, mean age=$39.6{\pm}11.6$ years, ranged age=20-77 years) completed Center for Epidemiologic Study-Depression (CES-D), Beck Suicide Intent scale (BSI), Spielberger State-Trait Anger Expression Inventory (STAXI), Barratt Impulsiveness Scale (BIS), Morningness-Eveningness Scale (MES) and brief questionnaire of sleep habits. Results: After controlling for age and sex, score of BSI was correlated positively with the score of CES-D, STAXI and BIS on partial correlation analysis ($r_p$=0.251; p<0.001, $r_p$=0.352; p<0.001, and $r_p$=0.175; p<0.001, respectively). In addition, score of BSI was inversely correlated with the score of MES (rp=-0.066; p=0.037). However, score of BSI showed no significant correlation with sleep duration. However, regression analysis revealed that short (<6 hrs) or long (>10 hrs) sleep duration, the family history of psychiatric illness, the score of CES-D, and the score of STAXI predicted higher score of BSI significantly in total subjects (F=17.837, adjusted $R^2$=0.166; p=0.003, p=0.003, p<0.001, and p=0.003, respectively). This model was explained better in depressed subjects with 16 or higher score of CES-D (F=9.920, adjusted $R^2$=0.298). Conclusion: Current result suggested that not only short sleep duration (<6 hrs) but also long sleep duration (>10 hrs) might be related to suicidality.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.57-70
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• 2015

Recently, soil erosion have been thickening from heavy rainfall according to climate change. These soil erosion is main reason to cause landslide, the water quality, agricultural counterproductivity and so on. Therefore, it is important to find out the main source area to cause soil erosion using geospatial data including DEM, soil map and land cover those are very sensitive to soil erosion modeling. This study evaluated soil erosion using RUSLE model. Hyoja 4-Dong and Pyonghwa 2-Dong among Wansan-Gu showed high as 10,869 ton/yr and 10,477 ton/yr respectively and Ua 2-Dong of Deokjin-Gu showed high as 17,603 ton/yr in soil erosion. And Hyoja 1-Dong and Pyonghwa 1-Dong among Wansan-Gu showed high as $1,485.7ton/km^2$ and $1,297.0ton/km^2$ respectively and Inhu 3-Dong of Deokjin-Gu showed high as $2,557.7ton/km^2$ in unit soil erosion that was applied to the evaluation of soil erosion potential. It is anticipated that achievement of this study can apply to forecast and prepare the risk of soil erosion and debris flow in urban area.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.337-341
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• 2009

지구의 평균기온이 지속적으로 상승함에 따라 지구온난화로 인한 기후변화는 지구에 분포되어 있는 극지방의 빙하들을 녹임으로써 지구의 물 순환시스템을 교란시켜 집중호우와 태풍, 가뭄, 낙뢰 등 예측을 불허하는 극한 기상변화를 발생시키고 있다. 기후변화로 인해 바다의 수온이 상승함에 따라 빙하가 녹거나 바닷물이 팽창하여 해수면이 상승하게 되는 바, 1990년 대비 2000년대에 동해바다에서는 상승률이 0.07cm/yr이던것이 0.20cm/yr로 나타났으며, 서해바다에서는 0.14cm/yr이던 것이 0.18cm/yr로 나타났고, 남해바다에서는 0.32cm/yr이던 것이 0.34cm/yr 로 평균상승률이 1990년대에 비해 증가하는 것으로 관측되었다. 본 연구에서는 기후변화로 인한 자연재해 피해를 최소화하기 위해 소방방재청의 현행 업무를 중심으로 재해를 예방하기 위한 풍수해 업무별 추진해야할 연구과제들을 조사 제시하고자 하였다. 기후변화에 따른 재난분야의 정책과 관련된 연구적인 측면의 분야를 제시하기 위하여 최근에 나타난 자연재난 피해현상에 대한 원인 및 대책을 기초로 하여, 재난관리분야에서 추진하고 있는 업무를 계승 발전시킴으로써 기후변화로 인한 피해를 예방 또는 최소화 할 수 있는 방향으로 제시하고자 하였다. 기후변화에 따른 소방방재청의 풍수해 재난관리 분야 종합계획을 제시하기 위해 본 연구에서는 기후변화 관련 최근 국내 외의 동향을 먼저 살펴보았다. 1977년부터 2006년까지 우리나라 최근 30년간의 재해연보에 제시되어 있는 시설물별 피해액을 조사하여 시설물 중 피해액이 많은 순으로 주요피해 시설물을 파악하였다. 여기에서 주요피해 시설물로는 하천, 도로, 소하천, 수리, 농경지, 사방 등의 순으로 나타났다. 이러한 주요시설물에 대한 피해현황을 파악하기 위하여 대규모 풍수해 피해에 대한 현황, 원인분석 및 대책이 제시되어 있는 각종 피해조사 보고서, 연구보고서 및 전문 학술지 기사들을 수집 분석하였으며, 수집된 자료를 토대로 각각의 재해피해현상에 대하여 시설물의 피해현상, 원인 및 대책을 분류하여 분석하고자 한다. 재난관리 분야 중 우수유출저감시설 관련 제시된 업무방향을 보면 침투 저류를 위한 우수유출저감시설의 개발연구, 침수위험지구의 지정기준 등급별 방재대책 방안연구, 유역별 재해위험 저감능력의 평가기준 개발, 단위구역별 우수유출저감시설의 확보기준 연구, 우수유출저감시설의 국내 표준화 방안 연구, 우수유출저감시설 설치자에 대한 인센티브 도입방안 연구, 피해지역의 매입을 통한 저류지화 방안 연구, 우수유출저감시설 설치효과의 교육 홍보 및 우수유출저감시설의 국제 표준화 기준 제정 추진 등이 필요할 것으로 조사되었다. 여기에서 제시된 재난관리 업무분야별 많은 연구과제들이 향후 연구할 수 있는 재원확보로 이어져 재난관리의 업무발전에 도움이 될 수 있도록 하여야 하겠으며, 주요 결론으로는 다음과 같다. 첫째, 우리나라는 기후변화에 대해서는 기존에 소극적으로 대응하였으나 기후변화대책기획단을 만들어 적극적으로 대처하고 있으므로 기후변화와 관련된 여러분야가 활성화 될 것으로 판단된다. 둘째, 국외의 기후변화 대응사례에서 보면 시설물의 규모를 볼 때 큰 규모의 예산을 투입하는 것으로 판단되는바, 이는 향후의 불확실한 기후변화에 대비하는 선진적인 판단으로 검토되어야 할 것이다. 셋째, 풍수해 관련 주요업무 8가지에 대하여 추진해야할 업무방향 48개를 선정 제시하였다.