• Title/Summary/Keyword: Location Sensor

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Effect of the Sensor Location on Magnetocardiography (심자도 센서의 위치 효과에 대한 연구)

  • Lim, Hyun-Kyoon;Kim, Ki-Woong;Kwon, Hyuk-Chan;Lee, Yong-Ho
    • Progress in Superconductivity
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    • v.10 no.1
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    • pp.1-5
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    • 2008
  • Magnetocardiography (MCG) is a non-contact, non-invasive, and harmless diagnostic tool to detect the abnormal electrical conductivities of the heart caused by the various coronary artery disease or cardiac muscular disease. The purpose of this study is to identify whether MCG signals and MCG parameter values vary depending on the location of sensor assembly. It will be an important reference for the standard measurement. Four healthy male subjects (33.3$\pm$6.3 years) participated in this study. Basal recording was made at 20 mm apart from the chest surface. All subjects were requested to take a regular breathe while MCG was taken. The gap between the chest surface and the bottom of the sensor assembly was 20, 40, 60, and 80 mm. Recording was made using 64 channel MCG system (Axial type, first order gradiometer) developed by Korea Research Institute of Standards and Science (KRISS). After resting for two minutes in a supine position on the bed in magnetically shielded room, MCG were recorded for 30 s. As the sensor location is getting away from the chest surface signal, the amplitude of R and T wave peak decreases to 70% (at 40 mm gap), 50% (at 60 mm), and 37% (at 80 mm) of the reference strength measured (y = $1.3903e^{-0.0169x}$, $R^2$ = 0.99; where y=amplitude remained after reduction, x=distance between chest surface and sensor location). The regression equations may be used as a good reference to calculate how much strength will be decreased by the distance. In MCG parameters, most values of parameters were decreased as the gap was increased. As an example, the current moment at T-wave peak reduced to 52% (at 40 mm gap), 33% (at 60 mm), and 19% (at 80 mm). However, the difference caused by the gap could be reduced by considering the distance when the MCG parameters were calculated. The study results can be used as a useful reference to design the baseline and the sensor location.

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Indoor Location Estimation and Navigation of Mobile Robots Based on Wireless Sensor Network and Fuzzy Modeling (무선 센서 네트워크와 퍼지모델을 이용한 이동로봇의 실내 위치인식과 주행)

  • Kim, Hyun-Jong;Kang, Guen-Taek;Lee, Won-Chang
    • Journal of the Korean Institute of Intelligent Systems
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    • v.18 no.2
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    • pp.163-168
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    • 2008
  • Navigation system based on indoor location estimation is one of the core technologies in mobile robot systems. Wireless sensor network has great potential in the indoor location estimation due to its characteristics such as low power consumption, low cost, and simplicity. In this paper we present an algorithm to estimate the indoor location of mobile robot based on wireless sensor network and fuzzy modeling. ZigBee-based sensor network usually uses RSSI(Received Signal Strength Indication) values to measure the distance between two sensor nodes, which are affected by signal distortion, reflection, channel fading, and path loss. Therefore we need a proper correction method to obtain accurate distance information with RSSI. We develop the fuzzy distance models based on RSSI values and an efficient algorithm to estimate the robot location which applies to the navigation algorithm incorporating the time-varying data of environmental conditions which are received from the wireless sensor network.

Development of 3-D viewer for indoor location tracking system using wireless sensor network

  • Yang, Chi-Shian;Chung, Wan-Young
    • Journal of Sensor Science and Technology
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    • v.16 no.2
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    • pp.110-114
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    • 2007
  • In this paper we present 3-D Navigation View, a three-dimensional visualization of indoor environment which serves as an intuitive and unified user interface for our developed indoor location tracking system via Virtual Reality Modeling Language (VRML) in web environment. The extracted user's spatial information from indoor location tracking system was further processed to facilitate the location indication in virtual 3-D indoor environment based on his location in physical world. External Authoring Interface (EAI) provided by VRML enables the integration of interactive 3-D graphics into web and direct communication with the encapsulated Java applet to update position and viewpoint of user periodically in 3-D indoor environment. As any web browser with VRML viewer plug-in is able to run the platform independent 3-D Navigation View, specialized and expensive hardware or software can be disregarded.

2D Location Estimation of a Magnetized Tip Using Arrayed GMR Sensors (GMR센서 배열을 이용한 자석팁의 2D 위치 추정)

  • Lee, S.C.;Kim, J.K.;Ahn, J.H.;Kim, H.Y.
    • Journal of Sensor Science and Technology
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    • v.28 no.6
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    • pp.395-401
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    • 2019
  • This paper proposes a method for estimating the location of a magnetized tip that is inside a non-transparent space or body by using arrayed giant magnetoresistance (GMR) sensors. In general, an object located in such an opaque space can be detected using X-rays, magnetic fields, ultra-sonic sensors, etc., depending on its characteristics. X-ray is mostly used for medical purposes but frequent exposure to it could cause harm to patients as well as doctors. In this study, how well a GMR sensor is applicable instead of an X-ray is investigated. The sensor's voltage output is experimentally fitted to distance with a relationship of 3rd degree polynomial. To detect a small magnetized tip with 900 Oe inside a human body, a 2×2 arrayed GMR sensor and a location estimation algorithm based on information acquired from four sensors is developed. Evaluation tests show that the suggested method is applicable to limited cases with a distance less than 33-55 mm, and the location of a magnet tip is estimated relatively well with an error less than 1.5 mm.

Positional Tracking System Using Smartphone Sensor Information

  • Kim, Jung Yee
    • Journal of Multimedia Information System
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    • v.6 no.4
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    • pp.265-270
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    • 2019
  • The technology to locate an individual has enabled various services, its utilization has increased. There were constraints such as the use of separate expensive equipment or the installation of specific devices on a facility, with most of the location technology studies focusing on the accuracy of location verification. These constraints can result in accuracy within a few tens of centimeters, but they are not technology that can be applied to a user's location in real-time in daily life. Therefore, this paper aims to track the locations of smartphones only using the basic components of smartphones. Based on smartphone sensor data, localization accuracy that can be used for verification of the users' locations is aimed at. Accelerometers, Wifi radio maps, and GPS sensor information are utilized to implement it. In forging the radio map, signal maps were built at each vertex based on the graph data structure This approach reduces traditional map-building efforts at the offline phase. Accelerometer data were made to determine the user's moving status, and the collected sensor data were fused using particle filters. Experiments have shown that the average user's location error is about 3.7 meters, which makes it reasonable for providing location-based services in everyday life.

Optimization of Piezoceramic Sensor/Actuator Placement for Vibration Control using Gradient Method (구배법을 이용한 진동제어용 압전 감지기/작동기의 위치 최적화)

  • 강영규;박현철
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.684-688
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    • 1998
  • Optimization of the collocated piezoceramic sensor/actuator placement is investigated numerically and verified experimentally for vibration control of laminated composite plates. The finite element method is used for the analysis of dynamic characteristics of the laminated composite plates with the piezoceramic sensor/actuator. The structural damping index(SDI) is defined from the modal damping. It is chosen as the objective function for optimization. Weights for each vibrational mode are taken into account in the SDI calculation. The gradient method is used for the optimization. Optimum location of the piezoceramic sensor/actuator is determined by maximizing tie SDI. Numerical simulation and experimental results show that the optimum location of the piezoceramic sensor/actuator is dependent upon the outer layer fiber orientations of the plate, and location and size of the piezoceramic sensor/actuator.

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Selection of Optimal Sensor Locations for Thermal Error Model of Machine tools (공작기계 열오차 모델의 최적 센서위치 선정)

  • 안중용
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.10a
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    • pp.345-350
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    • 1999
  • The effectiveness of software error compensation for thermally induced machine tool errors relies on the prediction accuracy of the pre-established thermal error models. The selection of optimal sensor locations is the most important in establishing these empirical models. In this paper, a methodology for the selection of optimal sensor locations is proposed to establish a robust linear model which is not subjected to collinearity. Correlation coefficient and time delay are used as thermal parameters for optimal sensor location. Firstly, thermal deformation and temperatures are measured with machine tools being excited by sinusoidal heat input. And then, after correlation coefficient and time delays are calculated from the measured data, the optimal sensor location is selected through hard c-means clustering and sequential selection method. The validity of the proposed methodology is verified through the estimation of thermal expansion along Z-axis by spindle rotation.

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A Three Dimensional Object Localization Scheme using A Smartphone (스마트폰을 이용한 물체의 3차원 위치 추정 기법)

  • Kwon, Oh-Heum;Joung, Myoung-Hwan;Song, Ha-Joo
    • Journal of Korea Multimedia Society
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    • v.20 no.8
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    • pp.1200-1207
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    • 2017
  • Sensors in a smartphone can be used to measure various physical quantities. In this paper, we propose an object localization scheme in a three dimenstional using a smart phone. The proposed scheme estimates the location of an object by observing it from several different points. The direction to the target object and the locations of the observation points are collected at each observation point using the location sensor and the orientation sensor in the smartphone. Based on these observations, the proposed scheme derives three dimensional line of sight vectors and estimates the location of the target object that minimizes the estimation error. We implemented the proposed scheme on an Android smartphone and tested its performance by estimating the height of a building and characteristics of the proposed approach.

Statistical Location Estimation in Container-Grown Seedlings Based on Wireless Sensor Networks

  • Lee, Sang-Hyun;Moon, Kyung-Il
    • International Journal of Advanced Culture Technology
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    • v.2 no.2
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    • pp.15-18
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    • 2014
  • This paper presents a sensor location decision making method respect to Container-Grown Seedlings in view of precision agriculture (PA) when sensors involved in tree container measure received signal strength (RSS) or time-of-arrival (TOA) between themselves and neighboring sensors. A small fraction of sensors in the container-grown seedlings system have a known location, whereas the remaining locations must be estimated. We derive Rao-Cramer bounds and maximum-likelihood estimators under Gaussian and log-normal models for the TOA and RSS measurements, respectively.

A Novel Hybrid Fault Location Sensor Employable to the Power Transmission Systems (가공 송전선의 사고 및 낙뢰 검출을 위한 새로운 하이브리드 센서)

  • Chang, Yong-Moo;Kang, Moo-Sung;Hwang, Ryul
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.07a
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    • pp.583-584
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    • 2005
  • In this work, a novel hybrid FL sensor consisting of two Rogowski coils has been designed for the installation on the ground wire of the transmission tower. The operation range of these coils is as follows: 30kA for the fault current comingfrom the ground fault or short-circuit and for the lightning current up to 150kA over 500kHz. Thus, two important functions could be provided: one is to detect the fault current and the other one is to find the fault location between towers or the location of induced lightning stroke. The on-site investigation at 800kV test yard has been under progress for its on-site application.

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