• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.577-588
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• 2017

There are many constraints, both economically and ethically that experimenting human evacuation behavior in situations such as fire. Therefore, the evacuation behavior is simulated based on the existing studies. In recent years, the foundation has been established as computer performance advances, models closer to reality can be studied. In this study, the evacuation time in the subway platform was analyzed from modeling human behavior and smoke propagation in a fire. The evacuation efficiency was also examined by dividing the shape of the subway station platform by the stair position and comparing the evacuation times for each platform. As a result, it was found that the side platform was longer than the island platform by 36.82% more time to evacuation. The shape of the stairs is most advantageous in terms of evacuation form side type platform was 210 seconds and island type platform was 186 seconds, when a fire occurs in the center of the platform. And most favorable in location of evacuation stairs were located at 2/5 point and 4/5 from depending on the step location.

• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.75-87
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• 2004

Along the seashore regions in Korea, though strong winds with very large strength are frequently witnessed, no system which can provide appropriate speed information for driving vehicle has been introduced. The driving against strong winds could be very dangerous because of the high possibility of accidents such as rollover and collision. These accidents usually resulted from driver's forced driving try even in difficult situation for steering vehicle, and sometimes overspeed without consideration of wind impact to the vehicles. To reduce accident caused by strong winds, it is important to inform drivers of appropriate driving speeds by perceiving strong winds. By setting up WIS at the main points where strong winds frequently appear and using the variable message sign(VMS) connected to the on-line whether information system, it tis possible to provide desired speed information, which can maintain vehicles' tractive force and maximum running resistance. The case study is conducted on the case of Mokpo-Big-Bridge, which is under construction at Mokpo city. The result show that in case the annual average direction of wind is South and the wind speed is over 8m/hr, the desired speed, which is required in order for vehicles running to South direction to maintain the marginal driving power, is 60km/hr. In addition, for the case of a typhoon such as Memi generated in 2003 year, if wind speed had been 18m/sec in Mokpo city at that time, the running resistance at the speed of 40km/hr is calculated as 1131N. This resistance can not be overcome at the 4th gear(1054N) level, therefore, the gear of vehicles should be reduced down to the 3rd level. In this case, the appropriate speed is 40km/h, and at this point the biggest difference between running resistance and tractive force is generated.

• Ecology and Resilient Infrastructure
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• v.4 no.2
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• pp.75-82
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• 2017

This study was executed to know the effect of the habitat size on huanren brown frog (Rana huanrensis) larvae's growth. We've conducted the study on Mt. Surak in Sanggye-dong, Nowon-gu, Seoul. Our study site was discriminated the huanren brown frog larvae's habitat into the three different areas, such as small area (S1, $3.91m^2$), middle area (S2, $4.42m^2$), and large area (S3, $38.37m^2$) in the same water channel. We measured two times per a week the 15 huanren brown frog larvae's body length, and developmental stages (foreleg, hind leg, tail length) including the environmental factors (humidity, air temperature and water temperature) of the study site from March 30 to June 28 in 2016. The only hatching rate was measured for the three egg sacs at the S2 study site. We found that the average hatching rate was $76.84{\pm}18.23(%)$ at S2. Generally, because of less precipitation during our study periods, all habitat areas for our study site were gradually decreased. The middle area, S2, was not reduced, the small area, S1, was reduced more than a fourth, and the largest area, S3, was drastically reduced more than half from initial area. There was no statistically difference among the three study sites for the three environmental factors (average humidity, average air temperature, and average water temperature) by F-test, but there were significant difference among the three site for the larvae's body length (F-test p< 0.05). Therefore, the larger of habitat areas, the larger of the larvae length as well as the faster of the larvae's developmental stages. When we measured the body lengths of immature huanren brown frogs, the immature frog of S1 was smallest, the immature frog of S3 was middle lenght, and the immature frog of S2 was largest. There were statistically different among the three study sites for the immature huanren brown frogs (F-test, p< 0.05). Because the S2 study site was relatively stable without rarely changing the study area, it meant that huanren brown frog was sensitive to habitat areas. Based on the results of this study, if we study on the effect of the altitude on the growth rate of huanren brown frog, it must be helpful in understanding the habitat environment of the population of huanren brown frog.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1135-1139
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• 2006

가뭄은 홍수와 함께 인류역사상 가장 큰 재해로 인식되어 있다. 미해양대기청의 발표에 따르면 20세기 최대 자연재해의 상위 5위 안에 4개의 가뭄이 포함되어 있다. 이러한 기록은 가뭄이 동서고금을 막론하고 국가의 흥망성쇠를 좌우할 만큼 막대한 피해를 입혀왔음을 의미한다. 그러나 가뭄의 해석은 가뭄의 정의 자체가 확실하지 않고 서서히 찾아오는 자연재해이기 때문에 그 시작과 끝을 인식하기 어렵다. 아울러 그 진행속도도 굉장히 느리며 또한 장기간에 걸쳐 지속되는 특성을 가지고 있고 시공간적으로 전파된다. 따라서 가뭄의 해석은 굉장히 까다로운 것이라 할 수 있으며 그 해석방법 또한 다양할 수 밖에 없다. 본 연구에서는 우리나라 전역 59개 지점의 표준강수지수(Standard Precipitation Index) 시계열 자료에 대한 공간적 패턴분석과 시간적인 자료확장을 시도하였다. 경험적 직교함수(Emperical Orthogonal function) 해석을 이용하여 자료의 공간적인 패턴을 확인하였고 EOF 해석에서 나타난 EOF Coefficient Time Series를 추계학적 모형에 적용하여 시간적인 자료 확장을 수행하였다. 이렇게 확장된 긴 기간의 자료를 이용하면 재현기간에 대한 평균적인 가뭄심도를 추출할 수 있으며 실제 나타난 사상의 재현기간이 어느 정도인지 평가할 수 있다. 또한 이렇게 나타난 가뭄심도를 강수부족량으로 환산하여 우리나라 대권역별 물부족량을 평가하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.167-167
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• 2022

최근 빅데이터에 관련된 연구에 있어 데이터의 품질관리에 대한 논의가 꾸준히 이뤄져 오고 있다. 특히 이미지 처리 및 분석에 활용되어온 딥러닝 기술의 경우, 분류 작업 및 패턴인식 등으로부터 데이터의 특징을 추출함으로써 비지도학습(Unsupervised Learning)을 가능하게 한다는 장점이 있음에도 불구하고 빅데이터를 다루는 과정에 있어 용량, 다양성, 속도 및 신뢰성 측면에서의 한계가 있었다. 본 연구에서는 CCTV 영상을 활용한 강수량 산정 모델 개발에 있어 예측 정확도 향상 및 성능 개선을 도모할 수 있는 데이터 전처리 방법을 제안하였다. 서울 근린 AWS 4개소 지역(김포장기, 하남덕풍, 강동, 성남) 및 중앙대학교 지점 내 CCTV를 설치한 후, 최대 9개월의 영상을 확보하여 강수량 산정을 위한 딥러닝 모델을 개발하였다. 배경분리, 조도조정, 영역설정, 데이터증진, 이상데이터 분류 등이 가능한 알고리즘을 개발함으로써 데이터셋 자체에 대한 전처리 작업을 수행한 후, 이에 대한 결과를 기존 관측자료와 비교·분석하였다. 본 연구에서 제안한 전처리 방법들을 적용한 결과, 강수량 산정 모델의 예측 정확도를 평가하는 지표로 선정한 평균 제곱근 편차(Root Mean Square Error; RMSE)가 약 30% 감소함을 확인하였다. 본 연구의 결과로부터 CCTV 영상 데이터를 활용한 강수량 산정의 가능성을 확인할 수 있었으며 특히, 딥러닝 모델 개발시 필요한 적정 전처리 방법들에 대한 기준을 제시할 수 있을 것으로 판단된다.

• Journal of the Korean GEO-environmental Society
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• v.15 no.3
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• pp.65-74
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• 2014

Borehole investigation which is mainly used to figure out geotechnical characterizations at construction work has the benefit that it provides a clear and convincing geotechnical information. But it has limitations to get the overall information of the construction site because it is performed at point location. In contrast, geophysical measurements like seismic survey has the advantage that the geological stratum information of a large area can be characterized in a continuous cross-section but the result from geophysics survey has wide range of values and is not suitable to determine the geotechnical design values directly. Therefore it is essential to combine borehole data and geophysics data complementally. Accordingly, in this study, a three-dimensional spatial interpolation of the cross-sectional distribution of seismic refraction was performed using digitizing and geostatistical method (krigring). In the process, digital map were used to increase the trustworthiness of method. Using this map, errors of ground height which are broken out in measurement from boring investigation and geophysical measurements can be revised. After that, average seismic velocity are derived by comparing borehole data with geophysical speed distribution data of each soil layer. During this process, outlier analysis is adapted. On the basis of the average seismic velocity, integrated analysis techniques to determine the three-dimensional geological stratum information is established. Finally, this analysis system is applied to dam construction field.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.11-23
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• 2011

The objective of this paper is to develop a daily pattern clustering algorithm using historical traffic data that can reliably detect under various traffic flow conditions in urban streets. The developed algorithm in this paper is categorized into two major parts, that is to say a macroscopic and a microscopic points of view. First of all, a macroscopic analysis process deduces a daily peak/non-peak hour and emphasis analysis time zones based on the speed time-series. A microscopic analysis process clusters a daily pattern compared with a similarity between individuals or between individual and group. The name of the developed algorithm in microscopic analysis process is called "Two-step speed clustering (TSC) algorithm". TSC algorithm improves the accuracy of a daily pattern clustering based on the time-series speed variation data. The experiments of the algorithm have been conducted with point detector data, installed at a Ansan city, and verified through comparison with a clustering techniques using SPSS. Our efforts in this study are expected to contribute to developing pattern-based information processing, operations management of daily recurrent congestion, improvement of daily signal optimization based on TOD plans.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.8
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• pp.62-69
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• 1999

This paper presents a vision-based real-time traffic surveillance system. Current research in machine vision applied to traffic is due to its potential for more powerful process, its flexibility and its lower cost. Our traffic surveillance system consists of FPA and TSM on the Internet. The FPA provides image data, vehicle speed and vehicle density for the TSM. Traffic parameters, the vehicle speed and density, are extracted over many frames using differences between the sampling points of a background image and those of incoming frames. The FPA works by just processing groups of pixels without any understanding of the image. Although this system has an accuracy limitation, it can be used in applications requiring an approximate vehicle density and vehicle speed in real-time.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.18-23
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• 1984

Spatial variability of 96 laboratory-measured infiltration rates on the Hwadong SiCL was studied using geostatistical concepts. The measurement was made at the nodes of the regular grid consisting of 12 rows and 8 columns. Sample spacing within rows and columns was 3 and 2m, respectively. Kriging was a means of spacial prediction that can be used for the infiltration rate. It was optimal in the sense that it provided estimates at unrecorded places without bias and with minimum and known variance. An attempt has been made with original data to verily the validity of all assumptions (Stationarity, Variogram models, etc.) by Jack-knifing procedure and frequency distribution. Variogram models were not different from other models, such as linear in calculation of both kriged values and variances in justification of its choice for simplicity. Correlation coefficient for a one-to-one relationship between measured and kriged values was found to be 0.308, which was not significantly different at 1% significance level.

• Water for future
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• v.27 no.2
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• pp.111-120
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• 1994

In this experimental research, the maximum scour depth at pier was studied. The model of the pier of San Gye bridge in the Bocheong stream was set for experimental pier scour studies. Several model verification processes were conducted through the roughness comparisons between model and prototype, pursuring scour depth variations with time depending upon channel bed variation, the comparison of the ratio between falling velocities and shear velocities in the model and prototype, and the comparison of pier scour between experimental data and field measuring data. The experiments were conducted in the free flow conditions and pressure flow conditions. The maximum scour depth at piers in the pressure flow conditions is twice as much as compared to the free flow conditions. Also, the maximum scour depth variations are indicated in the figures based on the Froude numbers, opening ratios, water depths and approaching angles in the free surface flow conditions.