• Geophysics and Geophysical Exploration
• /
• v.10 no.4
• /
• pp.229-240
• /
• 2007

In this study, seismic anisotropic tomography algorithm was developed for imaging the seismic velocity anisotropy of the subsurface. This algorithm includes several inversion schemes in order to make the inversion process stable and robust. First of all, the set of the inversion parameters is limited to one slowness, two ratios of slowness and one direction of the anisotropy symmetric axis. The ranges of the inversion parameters are localized by the pseudobeta transform to obtain the reasonable inversion results and the inversion constraints are controlled efficiently by ACB(Active Constraint Balancing) method. Especially, the inversion using the Fresnel volume is applied to the anisotropic tomography and it can make the anisotropic tomography more stable than ray tomography as it widens the propagation angle coverage. The algorithm of anisotropic tomography is verified through the numerical experiments. And, it is applied to the real field data measured at limestone region and the results are discussed with the drill log and geological survey data. The anisotropic tomography algorithm will be able to provide the useful tool to evaluate and understand the geological structure of the subsurface more reasonably with the anisotropic characteristics.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.5
• /
• pp.7-15
• /
• 2022

Since the direct and indirect damage caused by the fire in the underground utility tunnel will cause great damage to society as a whole, it is necessary to make efforts to prevent and control it in advance. The most of the fires that occur in cables are caused by short circuits, earth leakage, ignition due to over-current, overheating of conductor connections, and ignition due to sparks caused by breakdown of insulators. In order to find the cause of fire at an early stage due to the characteristics of the underground utility tunnel and to prevent disasters and safety accidents, we are constantly managing it with a detection system using image analysis and making efforts. Among them, a case of developing a fire detection system using CCTV-based deep learning image analysis technology has been reported. However, CCTV needs to be supplemented because there are blind spots. Therefore, we would like to develop a high-performance acoustic-based deep learning model that can prevent fire by detecting the spark sound before spark occurs. In this study, we propose a method that can collect sound in underground utility tunnel environments using microphone sensor through development and experiment of prototype module. After arranging an acoustic sensor in the underground utility tunnel with a lot of condensation, it verifies whether data can be collected in real time without malfunction.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.4 no.3
• /
• pp.195-205
• /
• 2002

Most tunnel damage such as cracks or leakage which exist in tunnel liner commonly, is caused by the cavities that exist behind the tunnel liner, through the tunnel safety inspections. These cavities were analysed to check if they affect the stability of tunnels. This study is on the development of the controlled low-strength and flowable filling material which an be applied to the cavity behind the tunnel lining. The backfilling material studied here is crushed sand and stone-dust which is in cake-state and is a by-product obtained in the producing process of aggregate. Varying the compound mixing ratio, laboratory tests of compression test and chemical analyses were carried out. In addition, the material was applied to an old tunnel for the performance assessment.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2011.07a
• /
• pp.157-159
• /
• 2011

현재는 국토해양부의 "도로터널 방재시설 설치 지침"에 따라 1종 도로 터널 내 아날로그 AM/FM 라디오 재난방송시스템이 설치되어 운영 중이나 T-DMB의 경우 관련 시스템이 개발이 되어 있지 않았다. T-DMB는 개인용, 휴대용, 이동형의 디지털방송매체로서의 특징을 가지고 있으며 최근들어 수신기 보급 증가로 새로운 재난방송 매체로 부상하고 있는 현실을 감안하면 터널 및 지하공간에서 T-DMB 방송망과 수신기를 활용한 국지적 재난방송 기술 개발은 매우 필요하다. 이에 본 논문은 기존 T-DMB 방송서비스 권역 내에서 터널 및 지하공간 등 T-DMB 수신환경이 열악한 지역에서 평상시에는 T-DMB 방송을 중계하여 수신환경을 개선하고 재난발생 시에는 기존 T-DMB 단말기로 수신 가능하며 각 재난상황에 맞는 맞춤형 재난경보방송을 송신하는 T-DMB 재난방송시스템 및 관련기술을 소개한다.

• Journal of Korea Water Resources Association
• /
• v.53 no.4
• /
• pp.273-283
• /
• 2020

Quantitative forecasting of groundwater levels for the assessment of groundwater variation and vulnerability is very important. To achieve this purpose, various time series analysis and machine learning techniques have been used. In this study, we developed a prediction model based on LSTM (Long short term memory), one of the artificial neural network (ANN) algorithms, for predicting the daily groundwater level of 11 groundwater wells in Hankyung-myeon, Jeju Island. In general, the groundwater level in Jeju Island is highly autocorrelated with tides and reflected the effects of precipitation. In order to construct an input and output variables based on the characteristics of addressing data, the precipitation data of the corresponding period was added to the groundwater level data. The LSTM neural network was trained using the initial 365-day data showing the four seasons and the remaining data were used for verification to evaluate the fitness of the predictive model. The model was developed using Keras, a Python-based deep learning framework, and the NVIDIA CUDA architecture was implemented to enhance the learning speed. As a result of learning and verifying the groundwater level variation using the LSTM neural network, the coefficient of determination (R²) was 0.98 on average, indicating that the predictive model developed was very accurate.

• Explosives and Blasting
• /
• v.35 no.3
• /
• pp.31-54
• /
• 2017

In the countries operating nuclear reactors, the development of high-level radioactive waste(HLW) disposal technique is considered as an urgent and important issue for sustainable utilization of nuclear energy. In Korea, in which a low and intermediate radioactive waste repository is already operating, the construction of an underground research laboratory for in situ validation studies became a matter of interest with increasing concerns on the management of HLW. In order to construct and to operate an underground HLW repository safely in deep underground, the stability of rock mass should be guaranteed. As an important factor on rock stability, excavation damaged zone (EDZ) has been studied in many underground research laboratories in foreign countries. For accurate evaluation of the characteristics and effects of EDZ under disposal condition, it is required to use reliable investigation method based on the analysis of previous studies in similar conditions. In this study, status of foreign underground research laboratories in other countries, approaches for investigation the characteristics, size, and effect of EDZ, and major findings from the researches were surveyed and reported. This will help the accomplishment of domestic researches for developing HLW management techniques in underground research laboratory.

• Journal of Korea Water Resources Association
• /
• v.39 no.2 s.163
• /
• pp.121-126
• /
• 2006

Snowmelt effect is identified from the analysis of the relationship between precipitation and groundwater level(GWL) data and Severe drawdown of GWL is observed in drought. Groundwater dam Operation Index (GOI), which is developed for the optimal operation of groundwater dam, is calculated by taking common logarithm of the moving average(MA) of precipitation data for a certain period. The period can vary from watershed to watershed because the period is decided by picking the maximum correlation coefficient between GWL and GOI of several MAs of precipitation. For Ssangchun watershed, the correlation was the strongest when we apply 70 day MA for GOI calculation. Snowmelt effect is considered by applying the temperature change by elevation($0.5^{\circ}C$ decrease per 100m) and examining the areal distribution of the watershed by elevation. Snow event is assumed when the daily average temperature is below $0^{\circ}C$ and snowmelt is assumed when the temperature is above zero degree Celsius. Total snowmelt is assumed for the day. When the snow event is occurred the precipitation data is separated into two components, snow and rainfall. The areal distribution by elevation is used for the calculation in the separation. The correlation between GWL and GOI is higher when we consider snowmelt effect than we neglected it.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.8
• /
• pp.2774-2779
• /
• 2010

In this paper, we develope the bucket driven dredger for sludge treatment in box type culvert. The dreadger is opererated in $2m\;{\times}\;2m$ box type narrow culvert under the road, and controlled using remote controller on the remote zone. In order to operate under dangerous environment, we develope the bucket drived dredger, and we will commercialize the result.

• The Journal of Engineering Geology
• /
• v.4 no.1
• /
• pp.57-77
• /
• 1994

The best management programs(BMP) of groundwater resources is to proted from potential groundwater contanination and to use it as optimal yield. In this paper, the groundwater protection strategies and empirical assessment methodologies using in USA are presented. Those strategies shall be used for future groundwater management program of our country and part of them are alreay utilized for the protection plan of the groundwater resources.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2004.05b
• /
• pp.236-240
• /
• 2004

강변여과수의 과도한 취수는 제내지 지하수위 하강을 발생하게 되며 이로 인해서 제내지 농경지의 토양 건조도가 증가되어 과도한 관계용수의 보충이 필요할 뿐말 아니라 지하수위 하강으로 인한 기존 관정사용이 어려워져 더 깊은 새로운 관정을 개발해야만 한다.. 이러한 기하수위 하강을 저감시키기 위한 방안으로 제내 지측에 인공함양우물을 설치하는 방법 있다. 창원시 강변여과 시설에 적용한 결과 인공함양우물의 최적 위치는 취수정으로부터 세내지 측으로 200m 지점에 위치하며, 함양량을 취수량의 $5\%$를 유지하는 것이 지하수위를 저감하기위한 효과적인 조건으로 판단되었다.