• Journal of Korean Association for Spatial Structures
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• v.15 no.1
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• pp.8-13
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• 2015

본 기사에서는 실 사회기반시설물 및 건축물에 적용 가능한 무선 센싱 시스템을 소개하였다. 이는 실용성 및 적용성을 높이기 위해 일방향의 계층형 무선 통신 네트워크 형태를 가지며, 절전 기능을 사용한다. 또한 웹-기반의 관리 프로그램을 통해 원거리에 위치한 구조물의 구조반응을 언제, 어디서든 확인할 수 있다. 이는 자동 계측 및 무선 통신 기법을 사용하기 때문에 설치가 용이하고, 시공 작업의 방해가 적으며, 설치 이후의 유지관리 비용을 절감할 수 있는 이점이 있다. 그러나 실 구조물의 정확한 SHM을 위해서는 계측값의 분석 및 건전도평가 등에 관한 신뢰할 만한 기술 개발이 여전히 요구된다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.125-128
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• 2008

Studies for structure design has conducted in many research institutions. A basic concept of Performance-Based Design for structures was presented in seismic fields. Hereafter, Demand were defined to communicate owner's demand to designer by several research institution. Performance-Based Design is guaranteed by an accurate analysis from hazard affected to structures and from social, economical and environmental effects. It is essential to define Performance Level and Performance Objective to grasp accurate demand for structures. In this study, Performance Level and Performance Objective in ATC-40, FEMA-273 and Eurocode were defined to introduce Performance-Based Design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.19-25
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• 2016

Engineering structures including civil infrastructures require a life-cycle cost and benefit during their service lives. The service life of a structure can be extended through appropriate inspection and maintenance actions. In general, this service life extension requires more life-cycle cost and cumulative benefit. For this reason, structure managers need to make a rational decision regarding the service life management considering both the cost and benefit simultaneously. In this paper, the probabilistic decision tool to determine the optimal service life based on cost-benefit analysis is presented. This decision tool requires an estimation of the time-dependent effective cost-benefit under uncertainty to formulate the optimization problem. The effective cost-benefit is expressed by the difference between the cumulative benefit and life-cycle cost of a deteriorating structure over time. The objective of the optimization problem is maximizing the effective cost-benefit, and the associated solutions are the optimal service life and maintenance interventions. The decision tool presented in this paper can be applied to any deteriorating engineering structure.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.6 s.52
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• pp.125-132
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• 2006

This paper presents the feasibility of a lateral mode piezoelectric oscillator to detect damages in civil infrastructures. The lateral mode oscillator sensor is composed of an electronic feedback oscillator circuit and a piezoelectric lateral mode vibrator to be attached to a structure of interest. Damage to the structure causes a change in the impedance spectrum of the structure, which results in a corresponding change of a resonant frequency of the structure. The oscillator sensors can instantly detect the frequency change in a very simple manner. Feasibility of the piezoelectric oscillator sensor was verified in this work with a sample aluminum plate where artificial cracks of different lengths and number were imposed in sequence. Validity of the measurement was confirmed through comparison of the experimental data with the results of finite element analyses of a plate with cracks.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.134-141
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• 2011

There have been increased economic and societal demands to continuously monitor the integrity and long-term deterioration of civil infrastructures to ensure their safety and adequate performance throughout their life span. However, it is very difficult to continuously monitor the structural condition of the pipeline structures because those are placed underground and connected each other complexly, although pipeline structures are core underground infrastructures which transport primary sources. Moreover, damage can occur at several scales from micro-cracking to buckling or loose bolts in the pipeline structures. In this study, guided wave measurement can be achieved with a self-sensing circuit using a piezoelectric active sensor. In this self sensing system, a specific frequency-induced structural wavelet response is obtained from the self-sensed guided wave measurement. To classify the multiple types of structural damage, supervised learning-based statistical pattern recognition was implemented using the damage indices extracted from the guided wave features. Different types of structural damage artificially inflicted on a pipeline system were investigated to verify the effectiveness of the proposed SHM approach.

• The Science & Technology
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• v.35 no.6 s.397
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• pp.34-37
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• 2002

[Information Technology의 세계] 연산의 혁명 가져올 양자컴퓨터/[Bio Technology의 세계] 효소는 바이오산업 활로의 촉매/[Nano Technology의 세계] 나노복합재료는 미래 구조물의 기반/[Environmental Technology의 세계] 경유자동차 매연 후처리장치 기술개발ㆍ보급 시급

• Composites Research
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• v.18 no.3
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• pp.59-64
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• 2005

• The Journal of the Korea Contents Association
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• v.16 no.3
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• pp.11-21
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• 2016

Recently, structure safety management techniques using cutting-edge technology(Displacement senor, sensor of acceleration) has emerged as an important issue owing to the aging of infrastructure such as bridge and building. In general, the structural monitoring system for structure safety management is based on IT technology and it is expensive to install. In this paper developed an image-based structure dynamic characteristic analysis system prototype to assess the damage of structure in a more cost-effective way than traditional structure health monitoring system. The inspector can take a video of buildings or other structures with digital camera or any other devices that is passible to take video, and then using NCC calculation for image processing technique to get natural frequency. This system is analysis of damage of the structure using a compare between the frequency response ratio and functions when problems are occurs send alarm to administrator. This system is easier to install and remove than previous monitoring sensor in economical way.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.421-428
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• 2020

Recently, excellent thermal and electrical performance of cementitious composites by mixing nano materials are being studied. The purpose of this study is to research the heat generation and power consumption of rapid hardening nano-cementitious composites. The experiment was carried out after setting the rapid hardening cementitious material, curing day, and supply voltage as parameters. Rapid hardening nano-cementitious materials were classified into cement paste, mortar, and concrete The heat performance of all rapid hardening nano-cementitious composites in curing 1 day has increased over 10℃. The rapid hardening nano-cementitious composites can exhibit heat performance within 1 day. The heat performance of the rapid hardening nano-cementitious composites is maintained after 28 days.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.117-125
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• 2016

Current cities encounter various types of water problems due to rapid urbanization and climate change. The increasing significance of urban water problems calls for the establishment of resilient alternatives to prevent and minimize social loss that results from these phenomena. As a background research for establishing resilient infrastructures for the mitigation of urban water problems, we evaluated the robustness of structural alternatives for urban flood as a representative case. Combining the robustness index (RI) and the cost index (CI), we suggested the robustness-cost index (RCI) as an indicator of the robustness of structural alternatives, and applied the index to assess the existing infrastructures and structural alternatives (i.e., sewer network expansion, additional storage tank construction, and green roof construction) at a site prone to floods located around Gangnam-station, Seoul, Korea. At a rainfall intensity frequency range of 2 to 20 years, the usage of a storage tank and a green roof showed relatively high RCI value, with a variation of an alternative showing greater RCI between the two depending on the size of design rainfall. For a rainfall intensity frequency of 30 years, installing a storage tank with some green roofing was the most resilient alternative based on the RCI value. We proposed strategies for establishing resilient infrastructures for the mitigation of urban floods by evaluating the robustness of existing infrastructures and selecting optimal structural alternatives with the consideration of scales of design disaster.