• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1555-1565
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• 2010

This paper presents a new method for indentifying the location of impact source in a buried duct. In a gas pipeline, the problem of leakage occurs due to the mechanical load exerted by construction equipment. Such leakage can cause catastrophic disasters in gas supply industries. Generally, the cross-correlation method has been used for indentifying the location of impact source in a pipeline. Since this method involves the use of the dispersive acoustic wave, it derives an amount of error in process of estimating the time delay between acoustic sensors. The object of this paper is to estimate the time delay in the arrival of the direct wave by using the wavelet transform instead of the dispersive wave. The wavelet transform based method gives more accurate estimates of the impact location than the cross-correlation method does. This method is successfully used to identify the location of impact force in an actual buried gas duct.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.96-101
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• 2010

A pulse radar system has been developed recently to detect dormant underground tunnels that are deeply located at depths of hundreds of metres. To check the ability of the radar system to detect an obliquely oriented tunnel, five different borehole pairs in the tunnel test site were chosen so that the horizontal lines-of-sight cut the tunnel axis obliquely, in $15^{\circ}$ steps. The pulse radar signatures were measured over a depth range of 20 m around the centre of the air-filled tunnel. Three canonical parameters, consisting of the arrival time, attenuation, and dispersion time were extracted from the first and second peaks of the measured radar signatures. Using those parameters, the radar system can detect obliquely oriented tunnels at various angles up to 45 from the transmitter-receiver line of sight.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.31-38
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• 2015

Intelligent leak detection is an essential component of a underground water supply pipeline network such as a smart water grid system. In this network, numerous leak detection sensors are needed to cover all of the pipelines in a specific area installed at specific regular distances. It is also necessary to determine the existence of any leaks and estimate its location within a short time after it occurs. In this study, the leak signal properties and feasibility of leak location detection were investigated when concurrent leaks occurred at two points in a pipeline. The straight distance between the two leak sensors in the 100A sized cast-iron pipeline was 315.6 m, and their signals were measured with one leak and two concurrent leaks. Each leak location was described after analyzing the frequency properties and cross-correlation of the measured signals.

• 한국지구물리탐사학회:학술대회논문집
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• 2004.08a
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• pp.118-137
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• 2004

Recently underwater geophysical problems for historical relics or UXO's are raised frequently. This study includes the applicabilities and limitations of the recent underwater metal detector and domestic case stories for underwater survey by electrical and magnetic method. Direct or indirect case stories are electrical and vertical magnetic gradiometry surveys beneath Han-river bottom for planning subway tunnel, electrical exploration on lake-bottom, electrical exploration on the tidal flats using high-power transmitter, and borehole three-component magnetic and electromagnetic surveys for detecting the undersea objects. A design of potable real-time, high-speed measurement system using multi-channel array sensors is also introduced here. Further study will be focussed on practical field applications of the fast water-bottom scanning system which is lately required by actual field.

• Journal of Cadastre & Land InformatiX
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• v.45 no.2
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• pp.131-147
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• 2015

In modern society, as to the underground urban infrastructure facilities(communication electricity water and sewage gas etc.) were contained many risks because of excavating. The exact position of underground facilities and the attribute information should be built in order to prevent accidents. As the result of analyzing the public surveying results from 2004 to 2009, it shows that low detecting rate of water pipeline which is only 52.4%, because the exploration of electromagnetic induction only detect metal pipeline and positioning survey only detect new pipeline before burying. Therefore development and verification of the correct and efficient exploration techniques are needed to improve the detecting rate. In this study, determined based on the location measurement results for the non-metal pipes and metal pipes before burial. It was compared with values that obtained through the ground penetrating radar and electromagnetic induction detecting. As a result, detecting rate of the concrete section showed a 100%, unpaved section showed a 94.7%, asphalt section showed 60%. So it confirmed the applicability of the ground penetrating radar at underground facilities detecting.

• Geophysics and Geophysical Exploration
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• v.21 no.3
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• pp.139-149
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• 2018

The resistivity monitoring is a practical method to resolve changes in resistivity of underground structures over time. With the advance of sophisticated automatic data acquisition system and rapid data communication technology, resistivity monitoring has been widely applied to understand spatio-temporal changes of subsurface. In this study, a new 4D inversion algorithm is developed, which can effectively emphasize significant changes of underground resistivity with time. To overcome the overly smoothing problem in 4D inversion, the Lagrangian multipliers in the space-domain and time-domain are determined automatically so that the proportion of the model constraints to the misfit roughness remains constant throughout entire inversion process. Furthermore, a focusing model constraint is added to emphasize significant spatio-temporal changes. The performance of the developed algorithm is demonstrated by the numerical experiments using the synthetic data set for a time-lapse model.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.11-14
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• 2012

본 논문에서는 임베디드 시스템 기반 NXT 로봇을 제어하여 길찾기, 미로찾기, 장애물오르기 등의 주행을 수행하는 프로그램을 개발하는 것이다. 미로 찾기는 RBG 센서를 통해 트랙의 색을 구분하여 정해진 색을 따라 주행하는 하는 것이며, 장애물 미로구간에서는 NXT 로봇 자신이 장애물을 넘지 못한다는 것을 인식하여 미로를 찾아 빠져나가도록 초음파 센서를 이용한다. 초음파 센서로 자신이 통과할 수 있는 진입로로 판단되면 주행을 계속하며, 그렇지 않은 경우에는 좌우회전을 통해 미로구간을 통과한다. 마지막 계단식 장애물 구간에서는 접촉센서와 초음파 센서를 통해서 물체의 높이를 가늠하여, 접촉센서 값과 초음파 센서 값을 통해 프로그램은 통과 여부와 계단높이를 판단한다. 실험결과 로봇은 제어프로그램 시나리오에 따라 적절하게 수행함을 확인할 수 있었으며, 이와 같은 로봇 제어를 확대하면 사람을 대신하는 재난구조 활동, 전쟁시 지뢰탐지 및 적 정찰활동, 지하공동구 및 지하매설물 안전 점검활동 등을 수행하는 업무로 적용이 가능할 것으로 판단된다. 본 연구에서 사용한 로봇은 I-Brick이라는 마이크로프로세서를 통해 프로그램을 구동되며, 저 전력으로 I-Brick과 그와 연결된 센서와 서브 모터 등을 구동하고 제어하도록 설계하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.427-436
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• 2016

Due to disasters such as earthquakes and landslides in urban areas, persons have been buried inside collapsed buildings and structures. Rescuers have mainly utilized detection equipment by applying sound, video and electric waves, but these are expensive and due to the directional approaches onto the collapsed site, secondary collapse risk can arise. In addition, due to poor utilization of such equipment, new human detection technology with quick and high reliability has not been utilized. To address these issues, this study develops a wireless signal-based human detection module that can be loaded into an Unmanned Aerial Vehicle (UAV). The human detection module searches for the 3D location for buried persons by collecting Wi-Fi signal and barometer sensors data transmitted from the mobile phones. This module can gain diverse information from mobile phones for buried persons in real time. We present a development framework of the module that provides 3D location data with more reliable information by delivering the collected data into a local computer in the ground. This study verified the application feasibility of the developed module in a real collapsed area. Therefore, it is expected that these results can be used as a core technology for the quick detection of buried persons' location and for relieving them after disasters that induce building collapses.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.549-558
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• 2021

In order to keep infrastructures such as tunnels and underground facilities safe, cracks of concrete lining in tunnel should be detected by regular inspections. Since regular inspections are accomplished through manual efforts using maintenance lift vehicles, it brings about traffic jam, exposes works to dangerous circumstances, and deteriorates consistency of crack inspection data. This study aims to provide methodology to automatically extract cracks from tunnel concrete lining images generated by the existing tunnel image acquisition system. Specifically, we train a deep learning based semantic segmentation model with open dataset, and evaluate its performance with the dataset from the existing tunnel image acquisition system. In particular, we compare the model performance in case of using all of a public dataset, subset of the public dataset which are related to tunnel surfaces, and the tunnel-related subset with negative examples. As a result, the model trained using the tunnel-related subset with negative examples reached the best performance. In the future, we expect that this research can be used for planning efficient model training strategy for crack detection.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.31-31
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• 2011

1990년 이후 공산체계인 구소련과 동구권이 몰락하고 세계적으로 탈냉전의 변화와 우리의 민주정부 수립 후 햇빛정책 등에도 불구하고 북한은 적화통일을 포기하지 않고 작년 11월에 연평도에 포격을 가하여 민간인과, 군이 2명이 사망하는 사건이 발생 하였다. 또한 북한의 공격은 과거의 포탄공격뿐만 아니라 미사일이나 화생방과 같은 생화학물질 탑재 가능한 공격이 예상된다. 이에 대비 정부에서는 고정시설의 화생방 방호는 일단유사시에 국민의 생명과 재산을 보호하는데 필수요소로서 집단보호개념에 도입하고 있으며, 현재 각 중요 대피시설 및 지자체의 기존 대피시설을 개인방호, 탐지, 제독, 운용절차를 포함한 실태파악 및 재래식 탄을 포함한 통합적인 조치를 마련하고 있다. 작년 2010년 11월 연평도에서의 북한 포격이후 우리는 서해5도나 접경지역 주민과 그리고 근접거리의 서울시민들이 안전하게 포격으로부터 피난 할 수 있는 민방위대피소에 대한 문제점이 대두되고 대책방안을 요구하고 있다. 소방방재청 기준에 따르면 직격(直擊) 핵폭탄을 제외한 화생방, 재래식 무기 공격에 견딜 수 있는 시설은 '1등급 대피시설'인데 서울에는 한 곳도 없다. 고층건물의 지하 2층 이하나 지하철, 터널 같은 2등급 대피시설도 폭격은 견딜 수 있지만 화생방 공격에는 취약하다. 지하상가 등 건축물의 지하층, 지하차도나 보도는 그보다 더 취약한 3등급이며 단독 주택의 지하층처럼 방호 효과가 떨어지는 곳이 4등급이다. 2등급으로 분류된 대피소의 경우 분류만 되어 있을 뿐 장기간 대피시 시민들이 사용 할 수 있는 거주공간이 아닌 임시 대피로서의 역할만 하고 있다. 본 연구에서는 민방위 기본법에 따라 지하에 $3.3m^2$ 당 4명 이상이 대피할 수 있는 규모의 공간을 갖추기만 하면 대피시설로 볼 수 있는 현 문제점과 1등급에서 4등급으로 나뉘어져있는 민방위 대피소와 대피소가 있지만 피난공간으로서의 역할과 구조적으로 안전한가에 대한 국내외 실태 분석을 통하여 분석한 결과 우리는 서해5도 대피시설의 반 이상이 무용지물이고 접경지 또한 피난시에 피난장으로서의 대피소가 난방이나, 구급품과 식구 시설 등이 구비가 되어 있지 않고 대피시설로 지정한곳이 간판이나 안내시설이 없다. 외국의 경우 스위스는 연방정부의 관리책임으로 전쟁이나 핵 확산에 따른 화생방 업무 전담팀을 두고 있으며, 방독면은 개인 방호물자로서 전국민 100% 보유하고, 각가정이나 건축, 시설물의 경우 화생방 표준 대피시설 설치관련 규정 마련 시행하고 있다. 대피시설은 화생방 방호가 가능한 지휘부용 대피시설과 일반 주민대피용 시설을 구분하여 설치운영하고 있으며, 전국에 650만개를 설치하고 있다. 결론은 대피시설이 북한 공경시 피난시설로의 활용방안을 모색 등급구분에 따른 현실적용 수정과 기존 대피소 보강과 재선별이 필요하고, 신축시 설계 표준설계안 그리고 기존의 대피소에 대한 보수, 보강방법 가이드라인과 장기간 거주에 대한 설비구축 등과 국민 대홍보등을 제안하였다.