• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.42-50
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• 2019

As the industry develops in Korea, the use of hazardous chemicals is increasing rapidly and chemical accidents are increasing accordingly. Most of the chemical accidents are caused by leaks of hazardous chemicals, but there are also accidents in which all the substances are released instantaneously due to sudden high temperature/pressure or defection of the storage tanks. This is called catastrophic failure and its frequency is very low, but consequence is very huge when it occurs. In Korea, there were 15 casualties including three deaths due to catastrophic rupture of water tank in 2013, and 64 instances of failures from 1919 to 2004 worldwide. In case of catastrophic failure, it would be able to overflow outside the bund that reduces the evaporation rate and following consequence. This incident is called overtopping. Overseas, some researchers have been studying the amount of external overflow depending on bund conditions in the event of such an accident. Based on the previous research, this study identified overtopping fraction by condition of bund in accordance with Korea Chemicals Controls Act Using CFD simulation. As a result, as the height increases and the distance to the facility decreases while meeting the minimum standard of the bund capacity, the overtopping effect has decreased. In addition, by identifying the effects of overtopping according to atmospheric conditions, types of materials and shapes of bunds, this study proposes the design of the bund considering the effect of overtopping caused by catastrophic failure with different bund conditions.

• 재활복지
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• v.20 no.1
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• pp.1-22
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• 2016

This research aimed to examine the problems in a current national emergency management system that does not consider the disabled in the face of manmade catastrophes and natural disasters, and to conduct an expert opinion survey to explore the direction of disabled-inclusive public disaster management system. As a result of the analysis, the respondents of the survey revealed a need for a designated government department for disaster management systems for the disabled and the experts preferred the Ministry of Public Safety and Security (50%) than the Ministry of Health and Welfare (37.5%). However, 12.5% of the surveyed experts perceived cooperation between the two Ministries, rather than selecting a certain ministry, as necessary to establish a disaster management system for the disabled. Additionally, the experts recognized the response period (43.8%) of the disaster management life cycle to be the most important phase. Thus, at the disaster response period, the experts suggested utilizing an emergency alarm system to effectively rescue the disabled in the face of disaster. Based on this discussion, the paper explores ways to establish a disabled-inclusive public disaster management system.

• Ecology and Resilient Infrastructure
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• v.6 no.2
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• pp.109-119
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• 2019

Eutrophication has occurred due to the inflow of various water pollutants in many Korean reservoirs with low depth, and algal blooms of surface layer and low oxygenation of deep layer have repeated every year. There are several existing technologies to alleviate the stratification of reservoirs, but it is difficult to apply them in field sites due to the necessity of electric power and low economic efficiency. In this study, a non-powered water circulation system using natural energy of wind and water flow has been developed, and two test-beds constructed in the reservoirs with different conditions and examined its field applicability. Through computational fluid dynamics (CFD) simulation, it has been shown that the water circulation system could induce the downward flow to mitigate the stratification between surface and deep layers, and its influence radius could reach about 30 m. As a result of long-term monitoring of the test-beds, various water quality improvement effects have been observed such as moderation of DO fluctuation by water circulation, reduction of DO supersaturation and prevention of excessive pH rising. In order to improve the applicability of the water circulation system, it is considered necessary to review countermeasures against flood and depth conditions of each reservoir.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.541-552
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• 2018

The implementation of drought measures in the upstream areas of river basins is seldom considered with respect to water supply. However, the demand for such measures is increasing rapidly owing to the occurrence of severe droughts, and interventions on streams and the water supply are needed. Physical interventions are an option to prevent streams from becoming dry and to maintain stream water flow, but dam construction is challenging because of environmental and ecological considerations. Here, a feasibility study was conducted to assess the potential effects of sand dams, which are widely used in arid regions in Africa. The SWAT-K model, which is a hydrologic model used for Korean watersheds, is used to estimate the flow rate of water in an ungauged watershed. The changes in water storage of the sand-dammed reservoir and in downstream flow rates are estimated for two types of sand dam (natural and dredged). The results show that sand dams are capable of increasing the downstream flow rate during normal conditions and of mitigating water supply problems caused by the withdrawal of water during drought periods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.3
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• pp.381-389
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• 2019

It is important to estimate flood overflow because adverse weather phenomena are frequently occurring in recent years. In order to cope with such abnormal floods, it is essential to perform flood inundation simulations for constructing flood inundation maps as nonstructural countermeasures. However, there is no quantitative evaluation method and criterion for flood inundation prediction. In this study, the Receiver Operation Characteristics (ROC) and Lee Sallee Shape Index (LSSI) were employed to quantitatively evaluate the accuracy of flood inundation maps for 10 administrative districts. Comparing predicted inundation maps with actual inundation trace maps, the ROC score was 0.631 and the LSSI was 25.16 %. Using the ROC and the LSSI, we proposed an evaluation criterion for flood inundation map. The average score was set as an intermediate score and distributed into 5 intervals. The validity of the evaluation criterion was investigated by applying to the XP-SWMM model, which has been verified and corrected. The ROC analysis result was 0.8496 and the LSSI was 51.92 %. It is considered that the proposed evaluation criteria can be applied to flood inundation maps.

• Korean Journal of Construction Engineering and Management
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• v.22 no.5
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• pp.29-38
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• 2021

Governments and companies are trying to reduce occupational accidents in the construction industry; however, the number of disasters are not decreasing significantly. This study aims to identify the correlation between factors affecting construction disasters quantitatively. To this end, 1,197 cases of serious disasters provided by Korea Occupational Safety and Health Administration (KOSHA) were analyzed using affinity analysis, one of the data mining techniques. The data from KOSHA were preprocessed and analyzed with variables of accident type, project type, activity type, original cause materials, sensory temperature, time of the accident, and fall height, and the association rules were derived for fall accidents and the others. For fall accidents, 64 association rules with lift ratios of 1.38 or greater were derived, and for the other accidents, 59 association rules with lift ratios of 1.54 or greater were derived. After analyzing the derived association rules focusing on the relationship among accident factors, this study presented the significance of applying the affinity analysis to address the study's limitations. The significance of this study can be found in that the correlation among factors affecting construction accidents is presented quantitatively.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.248-248
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• 2018

새만금 종합개발계획(정부, 2011)에 따른 내부개발의 완료시점은 2030년이며, 방수제 공사와 준설 등과 같이 만경강 및 동진강 유역 내 흐름을 변화시킬 수 있는 공사를 포함하고 있으므로 현재와 2030년의 하천 및 호의 수리특성은 다를 것이라 예상된다. 2030년까지 준설상황 등을 예측하여 반영하는 것은 사실상 불가능하기 때문에 새만금 종합개발계획에서 제시하고 있는 내부개발의 완료시점을 기준으로 홍수사상을 모의하였다. 새만금 호의 물리적인 변화는 수리특성의 변화로 이어질 수 있으며, 이는 상류지역으로 전파가 될 수 있으므로 호내 뿐만 아니라 만경강과 동진강 전역에 대한 홍수시의 수리특성을 검토하였다. 새만금 호와 연결된 만경강과 동진강의 설계홍수량은 대부분의 구간에서 100년 빈도이기 때문에 본 연구에서는 100년 빈도 홍수사상에 대한 분석을 기초로 홍수위 검토를 수행하였고, RCP8.5 시나리오를 적용한 100년 빈도 홍수량과 500년 빈도 홍수량에 대한 추가적인 연구를 수행하였으며, 이 결과를 토대로 취약지구 분석 및 대책 등을 제시하였다. 수치모의는 Delft3D를 이용하였으며, 새만금 유역의 동진강 지구의 실측치와 비교함으로써 모델의 적용성을 검증하였다. 서해안 조위 특성상 새만금 방조제는 조위 영향이 크므로, 이에 본 연구에서는 외조위의 특성을 고려하기 위해 새만금 유역 주변의 12개 조화상수(tidal harmonic constant)를 이용하여 조위에 대한 모의를 별도로 수행하고, 이 결과를 배수갑문의 경계조건으로 이용하였다. 상류 경계조건은 하천기본계획상에 제시된 하천은 이를 이용하였으며, 그 외의 소하천은 유역면적을 이용한 계산법을 사용하여, 선형적 면적 비유량(Specific Discharge, SD) 방법을 적용하여 본류의 유량에 부가하는 방식으로 수행하였다. 수치해석 결과, 준설 구간의 수위는 전반적으로 저하되었으며, 거리에 따른 수면의 경사를 분석한 결과 기존의 하천구역이 준설 등으로 인하여 호수의 특성으로 변화된 것으로 확인하였다. 본 연구에서 취약지구는 홍수위가 제방고의 약 80% 이상 되는 지역으로 결정하였으며, 이를 토대로 취약지구 분석을 수행한 결과 기존 100년 빈도에서 1지점, RCP 8.5 시나리오가 적용된 100년 빈도에서 88지점, 500년 빈도에서 125지점이 잠재적인 치수 위험이 있는 것으로 파악되었다. 기존의 1차원 연구결과와는 차이가 있는 부분은, 다수의 취약지구가 만곡부 또는 합류부 인근에 위치한 것이다. 향후 이러한 상대적인 치수 취약지점에 대해 정밀하고 국부적인 연구를 수행하여 정확한 홍수위 예측을 수행해야 할 것이다.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.238-247
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• 2020

This study aims to examine the causes of the rapid expansion of riparian vegetation in river channels in recent years. Accordingly, the changes in the monthly rainfall were analyzed at 19 locations over the period of 1984 to 2018. Moreover, the changes in the water levels of the target river sections of Seom River, Cheongmi River, and Naeseong River were analyzed. The results showed that rainfall increased by 30% in April and decreased by up to 49% in the May-September period since 2012. Between 2012 and 2018, when rainfall decreased, the inundation time of the floodplains of the target rivers decreased considerably. The floodplains of Seom River and Cheongmi River were not inundated since 2012 and 2013, respectively. In the case of Naeseong River, the inundation time of the low-water channel drastically decreased since 2013, and there was no inundation in 2015. Consequently, riparian vegetation settled rapidly on the floodplain without any disturbance and continued to expand. The settling and expansion of riparian vegetation reduce the flood capacity of the river channel and can also lead to the loss of the water ecosystem due to terrestrialization.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.649-661
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• 2020

Cut-slope management system (CSMS) has been investigated all slopes on the road of the whole country to evaluate risk rating of each slope. Based on this evaluation, the decision-making for maintenance can be conducted, and this procedure will be helpful to establish a consistent and efficient policy of safe road. CSMS has updated the database of all slopes annually, and this database is constructed based on a basic and detailed investigation. In the database, there are two type of data: first one is an objective data such as slopes' location, height, width, length, and information about underground and bedrock, etc; second one is subjective data, which is decided by experts based on those objective data, e.g., degree of emergency and risk, maintenance solution, etc. The purpose of this study is identifying an data application plan to utilize those CSMS data. For this purpose, logistic regression, which is a basic machine-learning method to construct a prediction model, is performed to predict a judging-type variable (i.e., subjective data) based on objective data. The constructed logistic model shows the accurate prediction, and this model can be used to judge a priority of slopes for detailed investigation. Also, it is anticipated that the prediction model can filter unusual data by comparing with a prediction value.

• Korean Journal of Construction Engineering and Management
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• v.23 no.4
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• pp.15-25
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• 2022

As the incidence and mortality of serious disasters in the construction industry are the highest, various efforts are being made in Korea to reduce them. Among them, risk assessment is used as data for disaster reduction measures and evaluation of risk factors at the construction stage. However, the existing risk assessment involves the subjectivity of the performer and is vulnerable to the domestic construction site. This study established a DB classification system for risk assessment with the aim of early identification and pre-removal of risks by quantitatively deriving risk factors using BIM in the risk assessment field and presents a methodology for risk assessment using BIM. Through this, prior removal of risks increases the safety of construction workers and reduces additional costs in the field of safety management. In addition, since it can be applied to new construction methods, it improves the understanding of project participants and becomes a tool for communication. This study proposes a framework for deriving quantitative risks based on BIM, and will be used as a base technology in the field of risk assessment using BIM in the future.