• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.739-742
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• 2008

Surface Image Velocity (SIV) is a technique which measures the surface velocity of river by using the principle of Paticle Image Velocimetry (PIV). The technique is economical and efficient way to measure velocity in rivers. The present paper aims to apply the technique to three rivers in Korea. It uses pairs of river surface images taken with two digital-cameras and reference points and cross section data which were acquired through plane survey. The performance of SIV was verified with automatic cart on an experimental flume. The test revealed that average error was less than 10 %, which assures that SIV can be used to measure velocity accurately. When it was applied to rivers with low water levels or rough weather condition, however, it showed the error about 20 %. If the problems of SIV technique are settled down, it can be one of the most convenient and economical ways to measure water discharge anytime and anywhere. And then it would be helpful to river management as developing a real-time river information system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.63-72
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• 2020

As the design complexity and performances are increased in satellite electronic board, noise related problems are also increased. To minimize the noise issues, various design improvements are performed by power integrity and signal integrity analysis in this research. Static power and dynamic power design are reviewed and improved by DC IR drop and power impedance analysis. Signal integrity design is reviewed and improved by time domain signal wave analysis and PCB(Printed Circuit Board) design modifications. And also power planes resonance modes are checked and mitigation measures are verified by simulation. Finally, it is checked that radiated noise is reduced after design improvements by EMC(Electro Magnetic Compatibility) RE(Radiated Emission) measurement results.

• Advances in environmental research
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• v.6 no.1
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• pp.67-81
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• 2017

Mining activities play a significant role in environmental pollution by producing large amounts of tailings which comprise heavy metals. The impressive increase in mining activities in recent decades, due to their high influence on the industry of developing countries, duplicates the need for a substantial effort to develop and apply efficient measures of pollution control, mitigation, and abatement. In this study, our objective was to investigate the effect of simulation of the leachate, pH and inflow intensity of transport of $Pb^{2+}$, $Zn^{2+}$, and $Cd^{2+}$ through Lakan lead and zinc plant tailings, in Iran, and to evaluate the modeling efficiency by comparing the modeling results and the results obtained from previous column studies. We used the HP1 model and the PHREEQC database to simulate metals transport through a saturated soil column during a 15 day time period. The simulations assumed local equilibrium. As expected, a lower pH and inflow intensity increased metal transport. The retardation of heavy metals followed the order $Zn^{2+}$ > $Pb^{2+}$ > $Cd^{2+}$ and the removal concentrations of Cd, Pb, and Zn at the inflow intensity critical scenario, and Cd and Pb at inflow acidity critical scenario exceeded the allowable EPA and Iranian's 1053 standard thresholds. However, although the simulation results generally agreed well with the results of the column study, improvements are expected by using multi-dimensional models and a kinetic modeling approach for the reactions involved. The results of such investigations will be highly useful for designing preventative strategies to control reactive transport of hazardous metals and minimize their environmental effects.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.429-429
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• 2011

우리나라는 연중 강우량의 계절적 편중이 심하여 약 2/3이 6월-9월에 집중하는 기상학적 요인과, 국토의 약 70%가 산악지역으로 되어있는 지형학적 요인 등 홍수에 취약한 자연특성을 갖고 있으며, 특히 하천, 도시 저지대, 해안 및 산지에서는 홍수범람, 내부배제 불량, 해일, 산사태 등으로 매년 많은 인명피해와 재산상의 손실이 크게 발생하고 있다. 또한 최근 발생하고 있는 이상기후 현상과 각종 개발사업으로 인한 불투수면적의 증가 등으로 인해서 극한 홍수의 발생빈도가 높아가고 있으나, 기존 수방시설물의 홍수배제능력 부족 등으로 매년 많은 피해를 입고 있는 실정으로, 구조적인 대책만으로는 재해피해를 경감시키는데 한계가 있음을 인식하여 구조적 대책과 더불어 토지이용규제 및 개발규제, 홍수터관리, 홍수예경보 등 비구조적 재해대 비능력 향상이 시급한 현황이다. 우리나라의 경우, 구조적 수방기술의 발전은 비교적 높은 수준에 도달해 있지만, 구조적 대책에 비해 비구조적 대책의 개발 및 적용은 미흡한 형편이므로, 비구조적 홍수대책의 종합적 정비 및 효율적 운영방법 필요하다. 따라서 본 연구에서는 홍수유형별 발생원인별 대표적인 비구조적 홍수대책을 국내외 적용사례를 조사하여 분석하고, 비구조적인 홍수방어대책들에 대한 장단점 및 적용성 등의 정성적 평가를 실시하였다. 국내 여건에 적합한 홍수위험구역 설정방안을 제시하고자, 국내의 다양한 하천공간 확보를 위한 관련규정인 하천구역, 홍수관리구역, 수변구역, 상수원보호구역, 친수구역, 홍수위험구역, 자연재해위험지구, 방재지구 등에 대하여 조사하였으며, 국외 사례로 영국의 홍수위험구역 평가제도, 미국의 홍수터 관리 프로그램, 호주의 하천공간 분류 기준, 일본의 하천공간 설정 기준 등에 대한 고찰을 수행하였다. 또한 국내 홍수보험 제도의 문제점 분석 및 제고방안을 제시하고자, 현재 소방방재청 주관으로 시행되고 있는 풍수해보험제도에 대한 조사 및 분석을 실시하였으며, 미국에서 시행되고 있는 국가홍수보험프로그램, 프랑스의 자연재해보험, 스위스의 자연재해보험풀 제도, 일본의 홍수보험제도에 대하여 심층적인 고찰을 수행하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.561-568
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• 2019

Recently, Korea has suffered from severe droughts due to climate change. Therefore, we need to pay attention to the change of drought risk to develop appropriate drought mitigation measures. In this study, we investigated the changes of hydrologic risk of extreme drought using the current observed data and the projected data according to the RCP 4.5 and 8.5 climate change scenarios. The bivariate frequency analysis was performed for the paired data of drought duration and severity extracted by the threshold level method and by eliminating pooling and minor droughts. Based on the hydrologic risk of extreme drought events Jeonbuk showed the highest risk and increased by 51 % than the past for the RCP 4.5 scenario, while Gangwon showed the highest risk and increased by 47 % than the past for the RCP 8.5 scenario.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.154-154
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• 2018

To interpret the climate projections for the future as well as present, recognition of the consequences of the climate internal variability and quantification its uncertainty play a vital role. The Korean Peninsula belongs to the Far East Asian Monsoon region and its rainfall characteristics are very complex from time and space perspective. Its internal variability is expected to be large, but this variability has not been completely investigated to date especially using models of high temporal resolutions. Due to coarse spatial and temporal resolutions of General Circulation Models (GCM) projections, several studies adopted dynamic and statistical downscaling approaches to infer meterological forcing from climate change projections at local spatial scales and fine temporal resolutions. In this study, stochastic downscaling methodology was adopted to downscale daily GCM resolutions to hourly time scale using an hourly weather generator, the Advanced WEather GENerator (AWE-GEN). After extracting factors of change from the GCM realizations, these were applied to the climatic statistics inferred from historical observations to re-evaluate parameters of the weather generator. The re-parameterized generator yields hourly time series which can be considered to be representative of future climate conditions. Further, 30 ensemble members of hourly precipitation were generated for each selected station to quantify uncertainty. Spatial map was generated to visualize as separated zones formed through K-means cluster algorithm which region is more inconsistent as compared to the climatological norm or in which region the probability of occurrence of the extremes event is high. The results showed that the stations located near the coastal regions are more uncertain as compared to inland regions. Such information will be ultimately helpful for planning future adaptation and mitigation measures against extreme events.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.725-744
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• 2022

As the construction of infrastructure using the underground tunnel in urban area have been rapidly increased, various accidents and collapses of tunnel including structure have been occurred in deep urban tunnelling. The concern and worry relating to the risk and safety of the tunnel during excavation is becoming the key issues in deep urban tunnelling. In this study, it was conducted for deep urban tunnel at GTX (Great Train Express) line which was located in Seoul metropolitan area to determine the risk characteristics for tunnel according to urban tunnelling. Also, it was reviewed the risk analysis and evaluation of the tunnel, shaft and station. And after a review of risk analysis and evaluation for risk register and hazard identification by using a risk matrix method, safety management of the tunnel according to excavation was evaluated to be secured. This study is expected to be applied as useful approach in deep urban tunnelling if you need to review the risk and safety management system of tunnel according to mitigation measures in complex urban tunnelling.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.5
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• pp.157-171
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• 2021

As smartphones spread and ICT technologies develop, taxi services have changed from hovering to platform-based calls and reservations. This has improved the mobility and accessibility of taxi users but caused problems, such as digital observing (no-responses to calls) for either short-distance services or services during the peak-demand periods. Digital Observing means ignoring and not accepting calls when they occur, which require improvement. Therefore, this study aims to derive measures to mitigate discrepancies in taxi supply and demand by adjusting the expected revenue of each taxi service using reinforcement learning based on the Taxi operation data. The results confirmed that the average complete response rate to calls would increase from 50.29% to 54.24% when incentives are applied, and an improvement of 5.86% can be achieved in short-distance sections of less than 5,000 won incentives. It is expected that the improvement will increase profitability for drivers, reduce the waiting time for passengers, and improve satisfaction with taxi services overall.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.5
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• pp.49-63
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• 2019

Crowdedness management at subway platforms is essential to improve services, including the prevention of train delays and ensuring passenger safety. Establishing effective crowdedness mitigation measures for platforms requires accurate estimation of the congestion level. There are temporal and spatial constraints since crowdedness on subway platforms is assessed at certain locations every 1-2 years by hand counting. However, smart cards generate real-time big data 24 hours a day and could be used in estimating congestion. This study proposes a model based on data from transit cards to estimate crowdedness dynamically. Crowdedness was defined as demand, which can be translated into passengers dynamically moving along a subway network. The trajectory of an individual passenger can be identified through this model. Passenger flow that concentrates or disperses at a platform is also calculated every minute. Lastly, the platform congestion level is estimated based on effective waiting areas for each platform structure.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.1
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• pp.145-159
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• 2019

A good number of drought indices have been introduced and applied in different regions for monitoring drought conditions, but some of those are region-specific and have limitations for use under other climatic conditions because of the inherently complex characteristics of drought phenomenon. Standardized Precipitation Index (SPI) indices are widely used all over the world, including Bangladesh. Although newly developed, studies have demonstrated The Effective Drought Index (EDI) to perform better compared to SPIs in some areas. This research examined the performance of EDI to the SPI for detecting drought events throughout 35 years (1981 to 2015) in Bangladesh. Rainfall data from 27 meteorological stations across Bangladesh were used to calculate the EDI and SPI values. Results suggest that the EDI can detect historical records of actual events better than SPIs. Moreover, EDI is more efficient in assessing both short and long-term droughts than SPIs. Results also indicate that SPI3 and the EDI indices have a better capability of detecting drought events in Bangladesh compared to other SPIs; however, SPI1 produced erroneous estimates. Therefore, EDI is found to be more responsive to drought conditions and can capture the real essence of the drought situation in Bangladesh. Outcomes from this study bear policy implications on mitigation measures to minimize the loss of agricultural production in drought-prone areas. Information on severity level and persistence of drought conditions will be instrumental for resource managers to allocate scarce resources optimally.