• Journal of Climate Change Research
• /
• v.3 no.1
• /
• pp.25-37
• /
• 2012

This research proposes the direction for the assessment of local government infrastructure vulnerabilities relating to climate change driven flood and analyzes the assessment result. In this research, the local government infrastructures are evaluated by three indices such as exposure, infrastructure sensitivity, adaptive capacity and each index is calculated by selected alternative variable. Climate change scenario(A1B) developed on National Institute of Environmental Research is used to calculate present and future(2020, 2050, 2100s) exposure. As the result of infrastructure vulnerability assessment on present, the infrastructures in Seoul, Northern Gyeonggi-do, Gangwon-do, coastal area of Gyeongsangnam-do are vulnerable to flooding. For future, although the spatial pattern of flooding vulnerable infrastructure are similar, the flooding vulnerabilities of infrastructure in Gyeonggido and Ganwon-do would be increased as close to 2100s. It is expected that this research can be utilized as the preliminary analysis for climate change adaptation in local government infrastructure because this research propose the method for the assessment of local government infrastructure vulnerability relating to climate change driven flood and the result such as a trend of infrastructure vulnerability to flooding and the level of contribution of each index and alternative variable.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.5B
• /
• pp.273-285
• /
• 2012

Current TMDL based on the 'Polluter Pays Principle' in Republic of Korea is individually operated by each local government for the designed allocated pollution load of unit watershed and unit district. However, unlike the motion of the air contaminants, the polluted contaminants in a river move from upstream to downstream, and a river can affect to districts more than two. In addition, a decision making on the construction of a sewage treatment facilities follows the concept of 'economy of scale'. These reasons support the collaboration among local governments in order to reduce the costs in improving water quality. This study suggested a method to reduce water quality management cost by redistributing reduction load considering cost-effectiveness for an entire watershed. The assessment on the suggested method is conducted in Youngsan river watershed. Without variation in total load, reduction load assigned for unit watershed and unit district is retributed in the region where pollutant source is concentrated, and then water quality and cost reduction improved from the redistribution of reduction load is analyzed. The results show that the cost saved by the suggested method is KRW 124 billion for scenario-1 and 172 billion for scenario-2 considering total cost of KRW 788 billion for the existing plan. We expect that the suggested method is a good example to reduce water quality management cost in local governments for TMDL.

• Journal of the Korea Society for Simulation
• /
• v.22 no.4
• /
• pp.67-82
• /
• 2013

This paper presents multi-fidelity modeling and simulation (M&S) methodology to enhance simulation performance of engineering-level defense models. In this approach, a set of models with varying degrees of fidelity is exercised to reduce computational expense maintaining a similar level of system effectiveness. For multi-fidelity M&S principles, this paper defines model fidelity from two perspectives (i.e., model behavior and execution), and suggests the Fidelity Change Point (FCP) to specify the fidelity conversion. With these concepts, this paper centers on three ideas: 1) two models' structure which are the Behavioral-Fidelity Interchangeable Model (B-FIM) and the Executional-Fidelity Interchangeable Model (E-FIM), 2) modeling formalism, and 3) a simulation algorithm to support them. From an abstract case study regarding a target tracking scenario with the utilization of the proposed method, we can gain interesting experimental results regarding the enhancement of simulation performance. Finally, we expect that this work will serve various M&S-based analysis areas for enhancing simulation performance.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2006.05a
• /
• pp.312-317
• /
• 2006

지역규모의 기후변화 모의결과를 이용하여 금강유역 용담댐의 홍수기 치수안전도에 대한 민감도분석을 수행하였다. 기후변화 모의에 사용된 SNURCM(Seoul National University Regional Climate Model)은 미국 National Center for Atmospheric Research의 Community Climate System Model의 전지구모형을 기반으로 spectral nudging 기법을 사용한 공간해상도 30 km, 연직 21층의 지역기후모형이다. 기후변화 시나리오로는 SRES 'B1'이 사용되었으며 과거 control run에 대한 기후모의 정확도 분석을 통하여 SNURCM 기상자료를 관측치와 비교한 결과 면적강우량을 다소 과소추정하였고 이점을 감안하여 SNURCM의 일 모의결과에 보정 계수를 적용하였다. 하천유출량은 SSARR 모형을 이용하여 SNURCM 모의가 수행된 전체기간을 $1980{\sim}1999$년과 $2000{\sim}2019$년으로 20년씩 나누어 용담댐 일 유입량을 산정하여 통계분석을 실시하였고 과거와 미래 20년 동안을 비교하여 본 결과 (1) 유량의 평균보다는 분산이 미래 20년 동안 증가하여 가뭄과 홍수에 대한 위험도가 증가함을 알 수 있었고, (2) 특히 연최대유량 또한 미래 20년 동안 상당히 증가하여 홍수기 치수대책이 더욱 중요해질 것으로 판단되었다. 마지막으로 용담댐 운영은 범용 시스템분석 도구인 STELLA(System Thinking Experimental Learning Laboratory with Animation) 상에서 GUI로 구현하여 유입량 변화에 따른 용담댐 치수안전도 변화를 모의해 보았다. 용담댐의 홍수기 운영은 저수지 수위가 제한수위를 초과하기 시작하면 Rigid ROM 발효하여 방류량을 결정하도록 구성하였고, 무효방류(spill)가 일어나는 현상을 실패로 가정하여 이에 대한 신뢰도(reliability), 회복도(resiliency), 그리고 심도(vulnerability)를 치수안전도 지표로 계산하였다. 전체기간을 1980년${\sim}$1999년, 2000년${\sim}$2019년, 2000년${\sim}$2009년, 그리고 2010년${\sim}$2019년까지 총 4구간으로 나누어 결과를 도출하였으며 예상한 바와 같이 후반기 20년 동안에 세 가지 지표가 취약해 지는 것을 확인할 수 있었고, 특히 2000년부터 2009년까지 10년 동안에는 더욱 취약해짐을 확인할 수 있었다.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.9 no.4
• /
• pp.60-67
• /
• 2010

Delay reduction of vehicles at the intersection is highly dependent on the signal operation method. Most previous traffic operations have focused on minimizing delay by adjust traffic offset. However, these methods have limitation in solving traffic problem if the volume reaches or exceeds the capacity. In this paper, it was analyzed that the effectiveness of various signal operation methods such as left-turn prohibition, and using protected mixed with permitted left turn using the traffic data from Daejeon city. In case of the left-turn prohibition of a intersection, the control delay reduced from 54.2 seconds to 22.7 seconds and especially, the delay of the southbound was drastically reduced. In addition, the delay was highly reduced from 27.0 seconds to 12.1 seconds when the operation system was changed to use protected mixed with permitted left turn.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.6B
• /
• pp.456-468
• /
• 2008

In this paper, we design Input/Output modules as a preference work for implementation of hybrid two stage AWG based WDM-PON and verify operations of each function modules through the logic simulation. This WDM-PON system provides service to 128 ONUs through 32 wavelength and one wavelength is shared for upstream transmission with four ONU while each wavelength is allocated to each ONU for downstream transmission. The designed WDM-PON MAC chip is based on sub-MAC which consists of one control unit and reception unit and four transmission unit. To design the reception and transmission unit of sub-MAC, we define the functions of the sub-MAC, pins of the modules, control signal and timing of each signal. We intend to design MAC chip with 1Gbps transmission rate. Thus the designed MAC chip is worked on 125MHz clock rate. We define FSM and design Input/Output modules with VHDL. The logic simulation of the modules is executed by the ModelSIM simulator.

• Journal of Korea Water Resources Association
• /
• v.56 no.10
• /
• pp.641-653
• /
• 2023

As climate change and urbanization are causing unprecedented natural disasters in urban areas, it is crucial to have urban flood predictions with high fidelity and accuracy. However, conventional physically- and deep learning-based urban flood modeling methods have limitations that require a lot of computer resources or data for high-resolution flooding analysis. In this study, we propose and implement a method for improving the spatial resolution of urban flood analysis using a deep learning based super-resolution technique. The proposed approach converts low-resolution flood maps by physically based modeling into the high-resolution using a super-resolution deep learning model trained by high-resolution modeling data. When applied to two cases of retrospective flood analysis at part of City of Portland, Oregon, U.S., the results of the 4-m resolution physical simulation were successfully converted into 1-m resolution flood maps through super-resolution. High structural similarity between the super-solution image and the high-resolution original was found. The results show promising image quality loss within an acceptable limit of 22.80 dB (PSNR) and 0.73 (SSIM). The proposed super-resolution method can provide efficient model training with a limited number of flood scenarios, significantly reducing data acquisition efforts and computational costs.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.3
• /
• pp.165-172
• /
• 2016

An experimental study of the thermal-hydraulic characteristics of passive safety systems (PSSs) was conducted using a system-integrated modular advanced reactor-integral test loop (SMART-ITL). The present passive safety injection system for the SMART-ITL consists of one train with the core makeup tank (CMT), the safety injection tank, and the automatic depressurization system. The objective of this study is to investigate the injection effect of the PSS on the small-break loss-of-coolant accident (SBLOCA) scenario for a 0.4 inch line break in the safety-injection system (SIS). The steady-state condition was maintained for 746 seconds before the break. When the major parameters of the target value and test results were compared, most of the thermal-hydraulic parameters agreed closely with each other. The water level of the reactor pressure vessel (RPV) was maintained higher than that of the fuel assembly plate during the transient, for the present CMT and safety injection tank (SIT) flow rate conditions. It can be seen that the capability of an emergency core cooling system is sufficient during the transient with SMART passive SISs.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.6
• /
• pp.439-449
• /
• 2021

The recent reduction in greenhouse gases, interest in environmental pollution such as low-carbon emission policies is increasing. Accordingly, the penetration rate of eco-friendly vehicles, including hydrogen battery vehicles capable of reducing carbon emission, is increasing, and thus it is required for disaster prevention and safety-related measures. In this study, the degree of risk for the concentration distribution of hydrogen when leaking hydrogen fuel vehicles according to ventilation conditions was analyzed through numerical analysis, limited to places in parking lots. As a result, when only one hydrogen tank was released, the combustible volume ratio of hydrogen in the underground parking lot was up to 8.6%, and as ventilation continued, the volume ratio of combustible hydrogen decreased to less than 1% after 150 seconds, indicating that mechanical ventilation is essential. In the case of simultaneous release or stage release of three hydrogen tanks, the final combustible volume ratio of hydrogen is similar, but the increase in the combustible volume ratio of hydrogen in the early stage of release is low, and further research is expected.

• Journal of Korean Society of Forest Science
• /
• v.101 no.3
• /
• pp.509-516
• /
• 2012

In this research, it was intended to examine the vulnerability of Pinus rigida to climate changes, a major planting species in Korea. For this purpose, the distribution of Pinus rigida and its changes caused by climate changes were estimated based on the 'A1B' climate change scenario suggested by IPCC. Current distribution of Pinus rigida was analyzed by using the $4^{th}$Forest Type Map and its potential distribution in the recent year (2000), the near future (2050) and the further future (2100) were estimated by analyzing the optimized ranges of three climate indices - warmth index(WI), minimum temperature index of the coldest month (MTCI) and precipitation effectiveness index(PEI). The results showed that the estimated potential distribution of Pinus rigida declines to 56% in the near future(2050) and 15% in the further future (2100). This significant decline was found in most provinces in Korea. However, in Kangwon province where the average elevation is higher than other provinces, the area of potential distribution of Pinus rigida increases in the near future and the further future. Also the result indicated that the potential distribution of Pinus rigida migrates to higher elevation. The potential distributions estimated in this research have relatively high accuracy with consideration of classification accuracy (44.75%) and prediction probability (62.56%).