• Title/Summary/Keyword: Mismatch Sensor

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Quantification of Acoustic Pressure Estimation Error due to Sensor Position Mismatch in Spherical Acoustic Holography (구형 음향 홀로그래피에서 측정위치 부정확성에 의한 음압 추정 오차의 정량화)

  • Lee, Seung-Ha;Kim, Yang-Hann
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.11a
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    • pp.1325-1328
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    • 2007
  • When we visualize the sound field radiated from a spherical sound source, spherical acoustic holography is proper among acoustic holography methods. However, there are measurement errors due to sensor position mismatch, sensor mismatch, directivity of sensor, and background noise. These errors are amplified if one predicts the pressures close to the sources: backward prediction. The goal of this paper is to quantitatively examine the effects of the error due to sensor position mismatch on acoustic pressure estimation. This paper deals with the cases of which the measurement deviations are distributed irregularly on the hologram plane. In such cases, one can assume that the measurement is a sample of many measurement events, and the cause of the measurement error is white noise on the hologram plane. Then the bias and random error are derived mathematically. In the results, it is found that the random error is important in the backward prediction. The relationship between the random error amplification ratio and the measurement parameters is derived quantitatively in terms of their energies.

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Quantification of Acoustic Pressure Estimation Error due to Sensor and Position Mismatch in Planar Acoustic Holography (평면 음향 홀로그래피에서 센서간 특성 차이와 측정 위치의 부정확성에 의한 음압 추정 오차의 정량화)

  • 남경욱;김양한
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1023-1029
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    • 1998
  • When one attempts to construct a hologram. one finds that there are many sources of measurement errors. These errors are even amplified if one predicts the pressures close to the sources. The pressure estimation errors depend on the following parameters: the measurement spacing on the hologram plane. the prediction spacing on the prediction plane. and the distance between the hologram and the prediction plane. This raper analyzes quantitatively the errors when these are distributed irregularly on the hologram plane The sensor mismatch and inaccurate measurement location. position mismatch. are mainly addressed. In these cases. one can assume that the measurement is a sample of many measurement events. The bias and random error are derived theoretically. Then the relationship between the random error amplification ratio and the parameters mentioned above is examined quantitatively in terms of energy.

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Analyses of additive Crypto-module Architecture for a Sensor Network (센서 네트워크를 위한 부가적인 암호모듈의 구조 분석)

  • Kim, Jung-Tae
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.795-798
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    • 2005
  • In this paper, we analyses of additive crypto-module architecture for a sensor network. Recent research in sensor networks has raised security issues for small embedded devices. Security concerns are motivated by the development of a large number of sensor devices in the field. Limitations in processing power, battery life, communication bandwidth and memoryconstrain devices. A mismatch between wide arithmetic for security and embedded data buscombined with lack of certain operations. Then, we compared the architecture of crypto-module in this paper.

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Crystallinity and Internal Defect Observation of the ZnTe Thin Film Used by Opto-Electronic Sensor Material (광소자로 사용되는 ZnTe박박의 결정성에 따른 결함 관찰)

  • Kim, B.J.
    • Journal of the Korean institute of surface engineering
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    • v.35 no.5
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    • pp.289-294
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    • 2002
  • ZnTe films have been grown on (100) GaAs substrate with two representative problems. The one is lattice mismatch, the other is thermal expansion coefficients mismatch of ZnTe /GaAs. It claims here, the relationship of film thickness and defects distribution with (100) ZnTe/GaAs using hot wall epitaxy (HWE) growth was investigated by transmission electron microscopy (TEM). It analyzed on the two-sort side using TEM with cross-sectional transmission electron microscopy (XTEM) and high-resolution electron microscopy (HREM). Investigation into the nature and behavior of dislocations with dependence-thickness in (100) ZnTe/ (100) GaAs hetero-structures grown by transmission electron microscopy (TEM). This defects range from interface to 0.7 $\mu\textrm{m}$ was high density, due to the large lattice mismatch and thermal expansion coefficients. The defects of low density was range 0.7$\mu\textrm{m}$~1.8$\mu\textrm{m}$. In the thicker range than 1.8$\mu\textrm{m}$ was measured hardly defects.

Parameter Mismatches and its Biases in Ocean Matched Field Processing (해양 정합장처리에서 매개변수 오정합과 바이어스)

  • Park Jae-Eun;Kim Jea-Soo;Shin Kee-Cheol
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.2
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    • pp.87-96
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    • 2005
  • In matched field processing (MEP), the observed acoustic field data is basically correlated with the replica produced by the modeling. therefore the results of source localization and correlation is limited by the mismatch of the environment and sensor location. In this paper. the effects of mismatch in environment and system on the bias in estimating the source location are investigated in the context of source localization. In the Pekeris waveguide, the simulation shows that the mismatches in environment and system, can cause a significant biases in the source localization and a degradation in MFP correlation. Mismatch caused by uncertainties in array tilt and depth, bottom depth, bottom sound speed, etc. causes degradation in source localization performance.

Stitching Method of Videos Recorded by Multiple Handheld Cameras (다중 사용자 촬영 영상의 영상 스티칭)

  • Billah, Meer Sadeq;Ahn, Heejune
    • Journal of Korea Society of Industrial Information Systems
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    • v.22 no.3
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    • pp.27-38
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    • 2017
  • This Paper Presents a Method for Stitching a Large Number of Images Recorded by a Large Number of Individual Users Through a Cellular Phone Camera at a Venue. In Contrast to 360 Camera Solutions that Use Existing Fixed Rigs, these Conditions must Address New Challenges Such as Time Synchronization, Repeated Transformation Matrix Calculations, and Camera Sensor Mismatch Correction. In this Paper, we Solve this Problem by Updating the Transformation Matrix Using Time Synchronization Method Using Audio, Sensor Mismatch Removal by Color Transfer Method, and Global Operation Stabilization Algorithm. Experimental Results Show that the Proposed Algorithm Shows better Performance in Terms of Computation Speed and Subjective Image Quality than that of Screen Stitching.

Submodule Level Distributed Maximum Power Point Tracking PV Optimizer with an Integrated Architecture

  • Wang, Feng;Zhu, Tianhua;Zhuo, Fang;Yi, Hao;Shi, Shuhuai
    • Journal of Power Electronics
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    • v.17 no.5
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    • pp.1308-1316
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    • 2017
  • The distributed maximum power point tracking (DMPPT) concept is widely adopted in photovoltaic systems to avoid mismatch loss. However, the high cost and complexity of DMPPT hinder its further promotion in practice. Based on the concept of DMPPT, this paper presents an integrated submodule level half-bridge stack structure along with an optimal current point tracking (OCPT) control algorithm. In this full power processing integrated solution, the number of power switches and passive components is greatly reduced. On the other hand, only one current sensor and its related AD unit are needed to perform the ideal maximum power generation for all of the PV submodules in any irradiance case. The proposal can totally eliminate different small-scaled mismatch effects in real-word condition and the true maximum power point of each PV submodule can be achieved. As a result, the ideal maximum power output of the whole PV system can be achieved. Compared with current solutions, the proposal further develops the integration level of submodule DMPPT solutions with a lower cost and a smaller size. Moreover, the individual MPPT tracking for all of the submodules are guaranteed.

Study of Magnetic Sensor Harmonic Reduction to Improve Direct Driven Motors Performance Applied to Platform Screen Doors (스크린도어용 다이렉트 드라이브 모터 성능개선을 위한 자기식 센서의 고조파 저감 연구)

  • Kim, Yun-Soo;Lee, Ju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.11
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    • pp.1645-1650
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    • 2015
  • This paper presents the 3-dimensional electromagnetic field analysis method and correction of sensor distortion that is used by a motor speed sensor. The magnetic sensors are being expanded due to lower price than the other speed sensors such as resolver and encoder. Magnetic sensor generates sine and cosine waves when the motor rotates. However, the sine and cosine signals are distorted due to magnetic noise, which makes the angle error of the sensor, generated near by the Hall element. This paper defines an optimal design variables by using the Taguchi method to minimize output distortion of the magnetic sensor and permanent magnet. To enhance reliability of the magnetic position sensor from sensitivity error, assembly amplitude mismatch and the electrical angle, 3-Dimensional electromagnetic finite element method and correction algorithm errors were performed in due of the magnetic sensor in order to improve the quality of the initial production model.

A Study on Development of Automatic Weld-Seam Tracking System using Vision Sensor (시각센서를 이용한 용접선 자동추적시스템의 개발에 관한 연구)

  • 배강열;이지형
    • Journal of Welding and Joining
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    • v.14 no.4
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    • pp.79-88
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    • 1996
  • For improvement in productivity and weld quality, weld seam tracking and welding parameter control are very essential in the welding of a structure which can not be cxactly fit-up due to mismatch, discontinous gap, deflection, etc.. In this study, an automatic weld seam tracking system is developed for I-butt joint structure, and the system consists of XYZ working table, vision sensor and user interface program. In the developed vision sensor system, an image projection algorithm for weld-line detection and an adaptive current control algorithm for gap variation were implemented. The user interface program developed in this study by basing on the objct oriented concept could provide very convenient way to utilize the tracking system with the pull-down menu driven structure. The developed system showed a good seam tracking and weld quality control capability corresponding to deflected weld lines and gap variations.

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An implementation of a magnetic-field measurement system based on optical sensor (광센서를 이용한 자기장 계측 장치 구현)

  • Kim, Young-Soo;Park, Byung-Seok;Kim, Myong-Soo;Lim, Yong-Hun;Hyun, Duck-Hwa
    • Proceedings of the KIEE Conference
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    • 2002.11a
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    • pp.219-222
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    • 2002
  • In this paper, some parameters are studied for the performance improvement of a bulk optical magnetic-field sensor. The performance of optical magnetic-field sensor is influenced by optical intensity change and wavelength change of light source, and phase shift so called optical bias mismatch. A magnetic field measuring system based on optical Faraday sensor is implemented and tested in the current range from 10 ampere to 200 ampere. The test result shows implemented system has goof linearity.

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