• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.87-91
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• 2019

The diagnosis of the failure for the existing electrical facilities was based on regular preventive maintenance, but this preventive maintenance was limited in preventing a lot of cost loss and sudden system failure. To overcome these shortcomings, fault prediction and diagnostic techniques are critical to increasing system reliability by monitoring electrical installations in real time and detecting abnormal conditions in the facility early. As the performance and quality deterioration problem occurs frequently due to the increase in the number of users of the motor pump, the purpose is to build an intelligent control system that can control the motor pump to maximize the performance and to improve the quality and reliability. To this end, a vibration sensor, temperature sensor, pressure sensor, and low water level sensor are used to detect vibrations, temperatures, pressures, and low water levels that can occur in the motor pump, and to build a system that can identify and diagnose information to users in real time.

• 한국컴퓨터정보학회논문지
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• 제12권5호
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• pp.321-326
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• 2007

냉동 컨테이너의 내용물들은 적정 온도를 유지하지 못하면 화물의 파손이 발생할 수 있다. 현재 냉동 컨테이너는 전담 관리원이 주기적이고 수동적으로 컨테이너의 내부 온도를 감시한다. 그래서 컨테이너 내부 온도를 실시간으로 감시할 수 없기 때문에 화물에서 문제가 발생하면 즉각적으로 대응하지 못한다. 본 논문은 무선 센서 네트워크를 이용하여 냉동 컨테이너에 센서 노드를 탑재하여 컨테이너 내부 온도를 실시간으로 감시하는 시스템을 제안한다. 무선 센서 네트워크는 독립된 센서들을 물리적 공간에 배치하여 주위의 온도, 빛 가속도 등의 정보를 감지하여, 무선으로 전송할 수 있는 기술이다. 제안된 시스템은 냉동 컨테이너의 상태를 실시간으로 감시하기 때문에 컨테이너의 적정 온도를 유지함으로써 화물을 효율적으로 관리할 수 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제10권4호
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• pp.160-166
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• 2006

본 연구에서는 광섬유 FBG 센서를 이용, 곡률반경을 고려한 이 방향 변위(Two-Way Displacement)를 측정하여 변형각을 환산함으로써 상대좌표를 구하는 알고리즘을 정립하였으며 이를 이용하면 작은 변형에 대해서도 매우정확하게 상대변위를 구할 수 있음을 알 수 있었다. 이를 확인하기 위해 4.5m높이의 H형강에 고안된 이 방향 광섬유센서를 부착하여 횡 방향으로 외력을 가해서 발생한 변위를 수준측량과 일반적인 전자식 변위계로 동시에 측정하여 각각의 측정성능을 비교분석하였다. 그 결과, 광섬유센서의 분해능은 다른 센서시스템에 비해 월등하였으며 이차원 상대좌표의 측정이 가능함을 확인하였다.

• 한국안전학회지
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• 제36권5호
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• pp.71-78
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• 2021

There are regularly planned overhaul periods in thermal power plants, which involve the maintenance of the boiler of the power plants. However, thermal power plants workers are always exposed to risk during overhaul periods owing to the narrow space and significant dust inside the boiler. Therefore, it is essential to develop a safety monitoring system that is suitable for operating in this type of environment. In this study, we developed not only a worker three-dimensional (3D)-location monitoring system that can monitor and record the entry/exit of workers, their 3D-location, and fall accidents but also a method to secure the working environment and operation efficiency. This system comprises of a worker tag, which was equipped with an inertial measurement unit, a barometric pressure sensor, and a Bluetooth low energy (BLE), and the tags were given to each worker. In addition, the location of workers inside the boiler was measured using a pedestrian dead reckoning (PDR) method and BLE beacons. The location data of the workers tag were transmitted to the integrated database (DB) server through a gateway, and to the administrator monitoring system. The performance of the system was demonstrated inside an actual thermal power plant boiler, and the accuracy and reliability of the system were verified through a number of repeated tests. These results provide insights on designing a new system for monitoring enclosed spaces.

• Structural Monitoring and Maintenance
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• 제6권3호
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• pp.237-254
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• 2019

This paper presents an improved time series based damage detection approach with experimental verifications for detection, localization, and quantification of damage in shear-type structures under varying mass effects using output-only vibration data. The proposed method can be very effective for automated monitoring of buildings to develop proactive maintenance strategies. In this method, Auto-Regressive Moving Average models with eXogenous inputs (ARMAX) are built to represent the dynamic relationship of different sensor clusters. The damage features are extracted based on the relative difference of the ARMAX model coefficients to identify the existence, location and severity of damage of stiffness and mass separately. The results from a laboratory-scale shear type structure show that different damage scenarios are revealed successfully using the approach. At the end of this paper, the methodology limitations are also discussed, especially when simultaneous occurrence of mass and stiffness damage at multiple locations.

• 비파괴검사학회지
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• 제32권6호
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• pp.661-668
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• 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from $2.06m/s^2$ base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

• 한국정보통신학회논문지
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• 제13권1호
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• pp.186-192
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• 2009

최근 유비쿼터스 컴퓨팅에 대한 연구가 활발해지면서 무선 센서 네트워크는 설치의 용이함과 저렴한 구축비용으로 다양한 분야에 널리 사용되고 있다. 현재 상용화 되어 있는 산간 지역에서 사용가능한 균열 예측 시스템은 구축 방법이나 비용면에서 많은 부담이 되고 있다. 이에 대한 대안으로 저비용의 상용화된 무선 센서 네트워크를 이용한 사면 균열 예측 시스템을 제안한다. 제안 시스템은 센서 노드를 절벽이나 사면, 바위, 둑 등에 부착하기 쉽고 지형물의 원형 손상을 최소화 할 뿐만 아니라 설치 및 유지 보수비용이 기존의 시스템에 비하여 약 50% 정도에 불과한 장점을 갖는다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2015년도 춘계 종합학술대회 논문집
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• pp.15-16
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• 2015

Measuring sensor, equipment, ICT facilities and their software have relatively short life time comparing to constructional structure so that we should exchange or fix them continuously in the process of maintenance and management. In this paper, we propose a novel design of integrated maintenance, management, and measuring monitoring system applying the concept of mobile cloud. For the sake of disaster prevention for constructional structures such as bridge, tunnel, and other traditional buildings in the village of local heritage, we analyze status of these structures in the long term or short term period as well as disaster situations. Collecting data based on mobile cloud and analyzing future expectations based on probabilistic and statistical techniques, we implement our integrated monitoring system for constructional structures to solve these existing problems. Final results of this design and implementation are basically applied to the monitoring system for more than 10,000 structures spread over national land in Korea. In addition, we can specifically apply the monitoring system presented here to a bridge of timber structure in Asan Oeam Village and a traditional house in Andong Hahoe Village to watch them from possible disasters. Total procedure of system design and implementation as well as development of the platform LinkSaaS and application services of monitoring functions implemented on the platform. We prove a good performance of our system by fulfilling TTA authentication test, web accommodation test, and operation test using real measuring data.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.217-220
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• 2014

무선 센서 네트워크（Wireless Sensor Network, WSN）수많은 로우 코스트 센서 노드로 구성하고 공동으로 배치된 지역 내에서 정보감지, 수집, 처리 및 전송임무를 수행한다. 광범위하게 국방군사, 지능형 교통, 의료구조, 환경감시, 정밀농업 및 공업 자동화등 방면에 응용할 수 있다. 데이터 유지관리 기술은 센서 네트워크의 핵심 기술 중 하나이다. 본 논문은 현재 무선 센서 네트워크 데이터 관리 기술 분석하고 문제점 지적하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.393-398
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• 2008

With the substantial increase of the size of structure, management and monitoring of excavation for the foundation construction becomes more difficult. Therefore, massive collapses which are related to retaining wall recently increase. However, since the study on measuring and monitoring the pre-stressing force of anchor is insufficient, behavior of anchor may not be predicted and monitored appropriately by the existing strain gauge type monitoring system. FBG Sensor, which is smaller than strain gauge and has better durability and does not have a noise from electromagnetic waves, was adapted to develope a smart anchor. A series of pullout tests were performed to verify the feasibility of smart anchor and find out the load transfer mechanism around the steel wire fixed to rock with grout.