• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.425-427
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• 2018

As the urban scale changes and the living space changes in three dimensions, the Ministry of Land, Infrastructure and Transport continuously builds various and high quality spatial information such as three-dimensional spatial information, indoor spatial information, underground spatial information and precision road map. However, although various disasters and safety accidents are rapidly increasing due to the enlargement and complexity of cities, safety management using spatial information is relatively insufficient. In this paper, we propose a data model for comparing and analyzing typical domestic and international spatial information construction cases and providing disaster safety services based on spatial information standards.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.197-200
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• 2005

도로에는 많은 종류의 지하시설물이 매설되어 있어 이에 대한 효율적인 관리를 위해 1995 년부터 국가적으로 국가지리정보체계 (NGIS:National Geographic Information System) 구축사업을 시작하였고, 많은 지방자치단체에서도 지하시설물 전산화를 통하여 시설물에 대한 DB 를 구축하여 전반적인 관리시스템을 갖추어 놓았다. 아울러 지하시설물 기관별로도 별도의 유지관리시스템을 구축하여 운용하고 있다. KT 에서도 TOMS(선로도면시설관리시스템: Telephone Outside-plant Management System)를 이용하여 도면전산 DB로 활용하고 있으며 이를 기반으로 TOPS (선로시설설계시스템:Telephone Outside Plant Design System)로 공사 설계를 하고 있다. 하지만 지하시설물로써 원초적인 관로에 대한 설계시스템은 도면의 hand drawing 작성방식으로 도시 한후 MS windows 환경의 excel로 설계함에 따라 설계시간이 많이 소요 되는 실정이다. 따라서, 본 프로그램의 개발은 KT 통신 network 구축에 필요한 맨홀 및 관로등의 지하시설물에 대한 공사설계의 툴로써 전산화 설계를 가능하게 하고 공사감리업무 종사자들의 업무환경 개선을 위해 개발 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1045-1052
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• 2011

Recently, because of complex cultural space, underground space are becoming larger. Therefore, the demand for location-based services is growing. VLC (Visible Light Communication) is based on the LED lighting infrastructure so that suitable LBS (Location-based service) is possible for the targeted places in indoor space. To experiment with indoor LBS by VLC, we measure the identification distance according to variable angles between LED and photo diode. We send the different ASCII code for each LED light, then we found the maximum identification distance is 1.75m from LED lights. From the results of this experiment, we show that indoor navigation is possible.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1796-1803
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• 2015

Unlike commercial LTE network, LTE-R railway network is arranged along a railroad track and the base stations of the network (RUs) are also installed on the waysides. For urban railway systems that are composed of underground tunnels, the leakage coaxial cables are widely used due to the radio propagation characteristics in tunnels. In theory, the tunnel sections are interpreted as the waveguide with blank spaces and for this reason, the tunnel sections are expected to be better than open ground sections in terms of the radio propagation characteristics. In this paper, we analyze the radio propagation characteristics based on this theory by replacing the leakage coaxial cables in the network with Yagi antennas. The test has been carried out in the 2.2km tunnel in the Daebul test track of KORAIL with 2.6GHz LTE-R Network. The LTE-R applicability in urban railways has been tested through the analysis on the radio propagation characteristics with the unmanned train operation system in Daebul tunnel.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.248-248
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• 2007

Demands for electricity are growing, whereas the rate of electricity infrastructure's construction declines gradually. To keep the balance of the demand and supply, the share of underground transmission line will be increased from 8.3% to 10.5% in 2020 but it will be accompanied with enormous public expenses. A great concern in high capacity transmission is on the increase so as to maximize the spacial efficiency. High Temperature Superconducting (HTS) cable is in the lime light which has the merits of environment-friendly, low transmission loss and high transmission with low voltage, but the reliability verification as a power system is yet to be solved. KEPCO completed the installation and acceptance of $3{\phi}$, 22.9kV, 1250A class HTS cable system in 2006 and the long term test is in progress. The test results focusing on long term reliability are presented in this paper.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.10a
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• pp.33-41
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• 2008

The longest tunnel has been halted at Daekwanryung by the failure of the host country of the Winter Olympiad in 2014, but modern High-Power TBM will come to Korea to excavate these long tunnels to establish the better horizontal connection between the western and eastern countries to improve the strong powerful logistic strategy of Korean peninsula. Train operation provides a key function of air movements in a long underground tunnel, and heat generation from transit vehicles may account of the most heat release to the ventilation and emergency systems. This paper indicates the optimal fire suppress services and safety provision for the long railway tunnel which is designed twin tunnel with length 22km in Gangwon province of Korea. The design of the fire-fighting systems and emergency were prepared by the operation of the famous long-railway tunnels as well as the severe lessons from the real fires in domestic and overseas experiences. Designers should concentrate the optimal solution for passenger's safety at the emergency state when tunnel fires, train crush accidents, derailment, and etc. The optimal fire-extinguishing facilities for long railway tunnels are presented for better safety of the comfortable operation in this hard rock tunnel of eastern mountains side of Korea. Since year 1900, hard rock tunnel construction has been launched for railway tunnels in Korea, tunnels have been built for various purposes not only for infrastructure tunnels including roadway, railway, subway, and but also for water and power supply, for deposit food, waste, and oils etc. Most favorable railway tunnel system was discussed in details; twin tunnels, distance of cross passage, ventilation systems, for the comfortable train operations in the future.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.269-277
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• 2020

In this study, numerical analyses were conducted to investigate the load transfer mechanisms and dynamic responses between the vertical shaft and the surrounding soil using a dynamic analysis method and a pseudo-static method (called response displacement method, RDM). Numerical solutions were verified against data from the literature. A series of parametric studies was performed with three different transient motions and various surrounding soils. The results showed that the soil stratigraphy and excitation motions significantly influenced the dynamic behavior of the vertical shaft. Maximum values of the shear force and bending moment occurred near an interface between the soil layers. In addition, deformations and load distributions of the vertical shaft were highly influenced by the amplified seismic waves on the vertical shaft constructed in multi-layered soils. Throughout the comparison results between the dynamic analysis method and the RDM, the results from the dynamic analyses showed good agreement with those from the RDM calculated by a double-cosine method.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.547-554
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• 2018

Using crowdsourced sensor data collection technique, it is possible to collect high-density ground vibration data which is difficult to obtain by conventional methods. In this study, we have developed a crowdsourced ground vibration data collection system using MEMS sensors mounted on small electronic devices including smartphones, and implemented client and server based on the proposed infrastructure system design. The system is designed to gather vibration data quickly through Android-based smartphones or fixed devices based on Android Things, minimizing the usage of resource like power usage and data transmission traffic of the hardware.

• Korean Journal of Remote Sensing
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• v.40 no.2
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• pp.141-150
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• 2024

Ground subsidence in urban areas is mainly caused by anthropogenic factors such as excessive groundwater extraction and underground infrastructure development in the subsurface composed of soft materials. Global Navigation Satellite System data with high temporal resolution have been widely used to measure surface displacements accurately. However, these point-based terrestrial measurements with the low spatial resolution are somewhat limited in observing two-dimensional continuous surface displacements over large areas. The synthetic aperture radar interferometry (InSAR) technique can construct relatively high spatial resolution surface displacement information with accuracy ranging from millimeters to centimeters. Although constellation operations of SAR satellites have improved the revisit cycle, the temporal resolution of space-based observations is still low compared to in-situ observations. In this study, we evaluate the extraction of a time-series of surface displacement in Incheon Metropolitan City, South Korea, using the small baseline subset technique implemented using the commercial software, Gamma. For this purpose, 24 COSMO-SkyMed X-band SAR observations were collected from July 12, 2011, to August 27, 2012. The time-series surface displacement results were improved by reducing random phase noise, correcting residual phase due to satellite orbit errors, and mitigating nonlinear atmospheric phase artifacts. The perpendicular baseline of the collected COSMO-SkyMed SAR images was set to approximately 2-300 m. The surface displacement related to the ground subsidence was detected approximately 1 cm annually around a few Incheon Subway Line 2 route stations. The sufficient coherence indicates that the satellite orbit has been precisely managed for the interferometric processing.

• Geomechanics and Engineering
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• v.38 no.5
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• pp.507-515
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• 2024

An accurate estimation of the geotechnical parameters in front of tunnel faces is crucial for the safe construction of underground infrastructure using tunnel boring machines (TBMs). This study was aimed at developing a data-driven model for predicting the rock quality designation (RQD) of the ground formation ahead of tunnel faces. The dataset used for the machine learning (ML) model comprises seven geological and mechanical features and 564 RQD values, obtained from an earth pressure balance (EPB) shield TBM tunneling project beneath the Han River in the Republic of Korea. Four ML algorithms were employed in developing the RQD prediction model: k-nearest neighbor (KNN), support vector regression (SVR), random forest (RF), and extreme gradient boosting (XGB). The grid search and five-fold cross-validation techniques were applied to optimize the prediction performance of the developed model by identifying the optimal hyperparameter combinations. The prediction results revealed that the RF algorithm-based model exhibited superior performance, achieving a root mean square error of 7.38% and coefficient of determination of 0.81. In addition, the Shapley additive explanations (SHAP) approach was adopted to determine the most relevant features, thereby enhancing the interpretability and reliability of the developed model with the RF algorithm. It was concluded that the developed model can successfully predict the RQD of the ground formation ahead of tunnel faces, contributing to safe and efficient tunnel excavation.