• 디지털융복합연구
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• 제14권2호
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• pp.217-225
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• 2016

본 연구에서는 배회가능성이 있는 치매환자의 실종예방을 위하여 웨어러블 디바이스(Wearable Device) 형식의 블루투스 비콘을 활용한 치매환자의 실내위치기반 모니터링시스템을 제안하였다. 이 시스템은 치매환자의 관리범위내 존재유무를 확인해 주며 치매환자가 비콘의 신호수신 설정거리를 이탈하면 즉, 지정된 관리구역을 벗어나면 비상메시지가 보호자와 관리자의 스마트 디바이스로 전달되는 시스템이다. 이 시스템의 주요 특성은 비콘을 착용한 치매환자를 특정장소에 설치된 비콘 신호수신용 스마트 기기(AP)에서 신호를 감지하여 환자의 위치를 파악하는 가역적 방법을 적용한 것이다. 본 논문에서 제안하는 블루투스 비콘을 활용한 실내위치기반 치매환자 모니터링 시스템은 요양병원, 재가요양시설 등에서 생활하는 배회가능성이 있는 치매환자의 실종예방에 기여하는 효과적 시스템으로 생각된다.

• Smart Structures and Systems
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• 제32권4호
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• pp.195-205
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• 2023

The contact acoustic emission (AE) monitoring system is time-consuming and costly for monitoring concrete structures in large scope, in addition, the great difference in acoustic impedance between air and concrete makes the detection process inconvenient. In this work, we broaden the conventional AE source localization method for concrete to the non-contact (air-coupled) micro-electromechanical system (MEMS) microphones array, which collects the energy-rich leaky Rayleigh waves, instead of the relatively weak P-wave. Finite element method was used for the numerical simulations, it is shown that the propagation velocity of leaky Rayleigh waves traveling along the air-concrete interface agrees with the corresponding theoretical properties of Lamb wave modes in an infinite concrete slab. This structures the basis for implementing a non-contact AE source location approach. Based on the experience gained from numerical studies, experimental studies on the proposed air-coupled AE source location in concrete slabs are carried out. Finally, it is shown that the locating map of AE source can be determined using the proposed system, and the accuracy is sufficient for most field monitoring applications on large plate-like concrete structures, such as tunnel lining and bridge deck.

• Smart Structures and Systems
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• 제13권1호
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• pp.155-171
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• 2014

Various monitoring techniques are now available for structural health monitoring and Acoustic Emission (AE) is one of them. One of the major advantages of the AE technique is its capability to locate active cracks in structural members. AE crack locating approaches are affected by the signal attenuation and dispersion of elastic waves due to inhomogeneity and geometry of reinforced concrete (RC) members. In this paper, a novel technique is described based on signal processing and sensor arrangement to process multisensory AE data generated by the onset and propagation of cracks and is validated with experimental results from an in-situ load test. Considering the sources of uncertainty in the AE crack location process, a methodology is proposed to capture and locate events generated by cracks. In particular, the relationship between AE events and load is analyzed, and the feasibility of using the AE technique to evaluate the cracking behavior of two RC slab strips during loading to failure is studied.

• 한국멀티미디어학회논문지
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• 제24권12호
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• pp.1682-1692
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• 2021

Digital Twin, one of the core technologies of the Fourth Industrial Revolution, is attracting attention as a very suitable technology for disaster monitoring such as fires and earthquakes. In this paper, we implement a system equipped with UWB RTLS(Ultra-Wideband Real Time Location System), real-time remote control, and video streaming, which are element technologies for disaster monitoring digital twin. Since the proposed system structure is based on a cloud server, the actual location of the UWB indoor positioning-based client is transmitted to the user device in real time and stored on the cloud server for statistical and data analysis. In addition, we demonstrate through experiments that outliers occurs when the value of RSSI(Received Signal Strength Indicator) decreases due to communication collisions between UWB Tags, and propose an RSSI outlier correction algorithm to solve this problem.

• 산업공학
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• 제25권1호
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• pp.114-126
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• 2012

This study describes a real-time location monitoring system developed for efficient operation of workplace in plant equipment maker. This monitoring system can be applied for indoor and outdoor working environment respectively. By using the real-time tracking system based on RTLS, it is possible to track worker's movement and location of working object under indoor working environment. For outdoor working environment, the real-time monitoring system based on IDGPS is applied for work safety and balanced workload. A case study is provided to evaluate the performance of the real-time monitoring system.

• 응용통계연구
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• 제33권4호
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• pp.467-482
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• 2020

본 논문은 이분산성을 갖는 위치-척도 시계열 모형에서 모수의 변화에 대한 모니터링 절차를 연구한다. 모니터링 절차에서 수정된 잔차의 누적합을 이용한 탐지기를 소개하고 귀무가설과 대립가설 하에서 각각 모니터링 절차에 대한 점근적 성질을 규명한다. 그리고 모의실험과 사례 분석을 통하여 제안한 모니터링 방법의 성능이 우수함을 확인한다.

• Journal of information and communication convergence engineering
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• 제5권4호
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• pp.382-388
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• 2007

Indoor location system using wireless sensor network technology was applied for the status evaluation and activity monitoring of elderly person or chronic invalid at home. Location awareness application is transparent to the daily activities, while providing the embedded computing infrastructure with an awareness of what is happening in this space. To locate an object, the active ceiling-mounted reference beacons were placed throughout the building. Reference beacons periodically publish location information on RF and ultrasonic signals to allow application running on mobile or static nodes to study and determine their physical location. Once object-carried passive listener receives the information, it subsequently determines it's location from reference beacons. By using only the sensor nodes without any external network infrastructure the cost of the system was reduced while the accuracy in our experiments. was fairly good and fine grained between 7 and 15 cm for location awareness in indoor environments. Passive architecture used here provides the security of the user privacy while at the server the privacy was secured by providing the authentication using Geopriv approach. This information from sensor nodes is further forwarded to base station where further computation is performed to determine the current position of object and several applications are enabled for context awareness.

• 한국환경과학회지
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• 제20권1호
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• pp.81-91
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• 2011

Air quality monitoring networks are very important facilities to manage urban air pollution control and to set up an environmental policy. Since air quality monitoring network of Daegu was allocated from 1980s to mid-90s, there is need to reevaluate it and relocated its site. This study was evaluated the position of Daegu air quality monitoring station by unit environmental sensitivity index, grid emission rate, CAI (Comprehensive Air-quality Index) point. The investigation domain covered an area of 16 $\times$ 24 km centered at the metropolitan area of Daegu with grid spacing of 2 km. The location of alternative air quality monitoring networks was selected through optimization and quintiles analysis of total score. The result showed that all things considered, new air quality monitoring network need to install grid numbers 10, 28, 36, 37, 46. We also recommand three scenarios of alternative air quality monitoring network when considering unit environmental sensitivity index, emission rate and CAI point.

• 한국산학기술학회논문지
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• 제12권1호
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• pp.351-356
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• 2011

본 논문에서는 애완동물의 생활 패턴과 습성을 연구하기 위해, 초음파, 온도, 습도와 조도 센서를 이용한 애완동물 위치추적 및 원격모니터링 시스템을 설계하였다. 애완동물의 위치를 파악하기 위해 초음파를 사용하여 거리 계산을 하였고, WSN(Wireless Sensor Network)을 이용하여 애완동물이 위치하는 장소의 온도, 습도와 조도 같은 센싱데이터들은 싱크모트로 전송하였다. 애완동물 모니터링 시스템에서는 수신된 센싱데이터들을 실시간으로 데이터베이스에 저장하고, 실제 공간에서 애완동물의 위치를 파악하였다. 송신모트들 사이의 간섭(interference) 문제는, 싱크모트의 비콘을 기준으로 송신모트들 간에 순차적으로 전송함으로써 해결하였다. 탐색된 위치를 시간별로 분석하여 애완동물의 이동패턴과 이동영역, 온도, 습도와 조도 등을 GUI(Graphical User Interface) 형태로 나타내는 애완동물 모니터링 시스템을 실험실 모델로 구현 및 실험하였다.

• 상하수도학회지
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• 제33권5호
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• pp.389-394
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• 2019

In order to determine the location of average concentration and distribution status of dissolved oxygen in the rectangular aeration tank of the sewage treatment plant was analyzed and the difference of dissolved oxygen concentration was remarkable at each location. Compared with the computational fluid dynamics analysis, it was found that the results were consistent with the measurement results by showing the difference of dissolved oxygen concentration between the locations. Based on the measured data, the representative location of dissolved oxygen in aeration tank was selected by using statistical analysis method and the representative location was expressed in three-dimensional coordinates(LWH : 25%, 50%, 33%) from flow direction and left wall. Also the difference between the dissolved oxygen concentration at the actual measurement location and the average concentration value of the entire aeration tank was founded, and the equations for calibrating the automatic measurement data considering the actual measurement location were calculated.