• 한국해양공학회지
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• 제21권3호
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• pp.46-51
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• 2007

A multi-purpose environmental monitoring system has been developed as a commercially available standard using the technique of hetero-core spliced fiber optic sensors, for the purposes of monitoring large-scale structures and preserving natural environments. The monitoring system has been tested and evaluated in a possible outdoor condition, in view of the full-scale operation at actual sites to be monitored. Additionally, the developed system in this work conveniently provides us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. Two channels of optical fiber line were monitored in each channel, three displacement sensor modules were connected in series, in order to examine the performance to a pseudo-cracking experiment in the outdoor situation and to clarify temperature influences an the system, in terms of the coupling of optical connectors and the OTDR stability. The results from the pseudo-cracking experiment agreed with the actual cracks, by means of calculation, based an the detected displacement values and their geometrical arrangement of the used sensor modules. The temperature change, ranging from 10 to $20^{\circ}C$ resulting from the 10-days free running operation, was found to influence the system stability of ${\pm}10{\mu}m$, primarily due to the coupling instability of the used optical connectors. It was found that fusion splicing, rather than the use of connectors, reduced the fluctuation dawn to ${\pm}2{\mu}m$. The specification and performance of various option modules have been demonstrated to show the capability of inspecting various physical quantities by use of the single system, which would be suitable for multi-purpose environmental monitoring.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.731-748
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• 2010

Impact detection and health monitoring are very important tasks for civil infrastructures, such as bridges. Piezoceramic based transducers are widely researched for these tasks due to the piezoceramic material's inherent advantages of dual sensing and actuation ability, which enables the active sensing method for structural health monitoring with a network of piezoceramic transducers. Wireless sensor networks, which are easy for deployment, have great potential in health monitoring systems for large civil infrastructures to identify early-age damages. However, most commercial wireless sensor networks are general purpose and may not be optimized for a network of piezoceramic based transducers. Wireless networks of piezoceramic transducers for active sensing have special requirements, such as relatively high sampling rate (at a few-thousand Hz), incorporation of an amplifier for the piezoceramic element for actuation, and low energy consumption for actuation. In this paper, a wireless network is specially designed for piezoceramic transducers to implement impact detection and active sensing for structural health monitoring. A power efficient embedded system is designed to form the wireless sensor network that is capable of high sampling rate. A 32 bit RISC wireless microcontroller is chosen as the main processor. Detailed design of the hardware system and software system of the wireless sensor network is presented in this paper. To verify the functionality of the wireless sensor network, it is deployed on a two-story concrete frame with embedded piezoceramic transducers, and the active sensing property of piezoceramic material is used to detect the damage in the structure. Experimental results show that the wireless sensor network can effectively implement active sensing and impact detection with high sampling rate while maintaining low power consumption by performing offline data processing and minimizing wireless communication.

• 한국통신학회논문지
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• 제36권12B호
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• pp.1708-1721
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• 2011

최근 구제역과 같은 가축질병으로 인한 살 처분된 가축매몰지의 적절한 모니터링 시스템의 필요성이 대두되고 있다. 그러나 현재 사용되는 모니터링 시스템은 살 처분된 매몰지 현장에서의 시료를 채취한 후 1~2주간의 모니터링 기간을 필요로 함으로 실시간 감시가 필요로 하는 매몰지에 대한 연속측정이 불가능하다. 이에 본 논문에서는 이런 실시간 모니터링을 가능하게 하는 우선 센서네트워크 기반의 가축매몰지 환경정보 모니터링 시스템 설계 및 구현을 제안한다. 제안된 시스템의 무선 센서노드는 환경센서(Dust, Co2, NH3, H2s, Temperature, Humidity)와 위치확인을 위한 GPS센서로 구성된다. 제안된 시스템은 게이트웨이를 통해 원격지 서버에 전송된 매몰지 환경정보를 분석함으로 언제 어디에서나 유해환경 모니터링이 기능하고 위치확인을 통한 상황에 따른 능동적인 대응을 가능케한다. 따라서 제안된 시스템의 유효성 검증을 위해 규정된 가스 배출관에 센서를 설치하였고, 통합 모니터링이 가능한 테스트 베드에서 실시간으로 수신된 데이터를 수집, 분석하여 시간의 변화에 따른 매몰지 위치의 악취환경변화를 모니터링 하였다. 이를 통한 상황에 따른 실시간 대응을 함으로 유사시 환경오염의 사전예방이 가능 한 것을 확인할 수 있었다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.11-13
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• 2005

The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) concluded that many collective observations gave a aspect of a global warming and other changes in the climate system. Future earth observation using satellite data should monitor global climate change, and should contribute to social benefits. Especially, human activities has given the big impacts to earth environment This is a very complex affair, and nature itself also impacts the clouds, namely the seasonal variations. JAXA (former NASDA) has the plan of the Global Change Observation Mission (GCOM) for monitoring of global environmental change. SGLI (Second Generation GLI) onboard GCOM-C (Climate) satellite, which is one of this mission, is an optical sensor from Near-UV to TIR. This sensor is the GLI follow-on sensor, which has the various new characteristics. Polarized/multi-directional channels and 250m resolution channels are the unique characteristics on this sensor. This sensor can be contributed to clarification of coastal change in sea surface. This paper shows the introduction of the unique aspects and characteristics of the next generation satellite sensor, SGLIIGCOM-C, and shows the preliminary research for this sensor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.439-441
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• 2007

The seoul metropolitan subway has installed 8 lines and about 500 stations to transport 5 million passengers everyday. The underground air pollution level in the subway stations is very severe status, which is very harmful to the commutators and its personals. Although subway roles as such a massive and huge transportation system, the subway doesn't adapt yet any real-time air monitoring system. They have only some hand-held type detector equipments for monitoring air pollution. Therefore subway passengers are exposed to the harmful air pollution environment. The most harmful environmental parameters among the air pollution are known as the dust and sound noise dB level in the subway station. Because the dust is consisted of very small particles, we can't see them easily in dark condition on the platform, but it is very harmful. The monitoring system for air pollution is developed using embedded system attached with 6 different environmental sensors. This system monitors air pollution of dust sound noise, gas, temperature, humidity, inflammable gas, toxic gas in the subway ?station. The sensor unit of the ARM-CPU board and sensor transmits real time environmental data to the main server using Zigbee wireless communication module and TCP/IP network. The main control server receives and displays the real-time environmental data, and it send alarms to the personals when high level value.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.250-252
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• 2002

The goals of environmental monitoring are to locate and quantify the significant contamination, estimate the fate and transport, estimate the potential exposure and risks to humans and the environment, and track the performance of various remedial technologies. In this study, ceramic gas sensor system is proposed to enhance the effectiveness of soil vapor extraction (SVE) process by monitoring the effluent gas. SVE is a technique that is widely used to remediate unsaturated soils contaminated with volatile organic contaminants. The sensor response for benzene, toluene, and xylene, the representative effluent gas compositions of SVE process, was evaluated using the proposed sensor system. As a result, it was verified that the response of sensor was increased or decreased very sensitively according to the change of the effluent gas concentration. Besides, the sensor could detect the difference over a wide range of concentration and it was more sensitive in order of xylene, toluene, and benzene. It is expected that this VOC analysis method results in field monitoring costs saying and appropriate immediate action for process control. More detailed experiments are being conducted in our research group.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.711-730
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• 2010

This study presents the design of autonomous smart sensor nodes for damage monitoring of tendons and girders in prestressed concrete (PSC) bridges. To achieve the objective, the following approaches are implemented. Firstly, acceleration-based and impedance-based smart sensor nodes are designed for global and local structural health monitoring (SHM). Secondly, global and local SHM methods which are suitable for damage monitoring of tendons and girders in PSC bridges are selected to alarm damage occurrence, to locate damage and to estimate severity of damage. Thirdly, an autonomous SHM scheme is designed for PSC bridges by implementing the selected SHM methods. Operation logics of the SHM methods are programmed based on the concept of the decentralized sensor network. Finally, the performance of the proposed system is experimentally evaluated for a lab-scaled PSC girder model for which a set of damage scenarios are experimentally monitored by the developed smart sensor nodes.

• Smart Structures and Systems
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• 제29권1호
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• pp.251-266
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• 2022

Structural Health Monitoring (SHM) of critical infrastructure comprises a major pillar of maintenance management, shielding public safety and economic sustainability. Although SHM is usually associated with data-driven metrics and thresholds, expert judgement is essential, especially in cases where erroneous predictions can bear casualties or substantial economic loss. Considering that visual inspections are time consuming and potentially subjective, artificial-intelligence tools may be leveraged in order to minimize the inspection effort and provide objective outcomes. In this context, timely detection of sensor malfunctioning is crucial in preventing inaccurate assessment and false alarms. The present work introduces a sensor-fault detection and interpretation framework, based on the well-established support-vector machine scheme for anomaly detection, combined with a coalitional game-theory approach. The proposed framework is implemented in two datasets, provided along the 1st International Project Competition for Structural Health Monitoring (IPC-SHM 2020), comprising acceleration and cable-load measurements from two real cable-stayed bridges. The results demonstrate good predictive performance and highlight the potential for seamless adaption of the algorithm to intrinsically different data domains. For the first time, the term "decision trajectories", originating from the field of cognitive sciences, is introduced and applied in the context of SHM. This provides an intuitive and comprehensive illustration of the impact of individual features, along with an elaboration on feature dependencies that drive individual model predictions. Overall, the proposed framework provides an easy-to-train, application-agnostic and interpretable anomaly detector, which can be integrated into the preprocessing part of various SHM and condition-monitoring applications, offering a first screening of the sensor health prior to further analysis.

• 한국재난관리표준학회지
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• 제1권3호
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• pp.77-81
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• 2008

본 논문에서는 기존 광파이버센서가 갖는 문제점을 보완할 수 있는 새로운 형태의 광파이버 센서에 대해 소개한다. 저자 등이 개발한 헤테로코어형 광파이버센서는 비교적 간단하면서도 큰 곡률 반경에 있어서 전달손실이 발생하며 민감한 손실특성을 나타내는 원리를 이용한 것이다. 또한 원리상 온도의존성이 거의 없어 온도보상이 필요 없고, 마크로벤딩에 의한 광량변화를 검출하는 방식이므로 파단우려가 없는 것도 가장 큰 장점 중의 하나이다. 이러한 특징을 갖는 센서에 대한 내환경특성을 분석하고 평가하기 위해, 본 논문에서는 헤테로코어 형 광파이버센서를 이용하여 각종 환경정보를 모니터링하는 광네트워크형 멀티환경 모니터링 시스템을 구성 할 경우 고려해야 할 특성에 대해 검토하였다. 즉, 온도변화에 대한 센싱 시스템의 강인성을 실험을 통해 확인하였다. 이것은 실용적 관점에서 계측시스템 전체의 환경변화에 대한 종합적인 평가를 수행하는 것을 의미하며 그 결과를 본 논문에 소개한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권5호
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• pp.1516-1539
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• 2022

This article shows a set of physical information fusion IoT systems that we designed for smart buildings. Its essence is a computer system that combines physical quantities in buildings with quantitative analysis and control. In the part of the Internet of Things, its mechanism is controlled by a monitoring system based on sensor networks and computer-based algorithms. Based on the design idea of the agent, we have realized human-machine interaction (HMI) and machine-machine interaction (MMI). Among them, HMI is realized through human-machine interaction, while MMI is realized through embedded computing, sensors, controllers, and execution. Device and wireless communication network. This article mainly focuses on the function of wireless sensor networks and MMI in environmental monitoring. This function plays a fundamental role in building security, environmental control, HVAC, and other smart building control systems. The article not only discusses various network applications and their implementation based on agent design but also demonstrates our collaborative information fusion strategy. This strategy can provide a stable incentive method for the system through collaborative information fusion when the sensor system is unstable in the physical measurements, thereby preventing system jitter and unstable response caused by uncertain disturbances and environmental factors. This article also gives the results of the system test. The results show that through the CPS interaction of HMI and MMI, the intelligent building IoT system can achieve comprehensive monitoring, thereby providing support and expansion for advanced automation management.