• Title/Summary/Keyword: Time of flight

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Enhancement on Time-of-Flight Camera Images (Time-of-Flight 카메라 영상 보정)

  • Kim, Sung-Hee;Kim, Myoung-Hee
    • 한국HCI학회:학술대회논문집
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    • 2008.02a
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    • pp.708-711
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    • 2008
  • Time-of-flight(ToF) cameras deliver intensity data as well as range information of the objects of the scene. However, systematic problems during the acquisition lead to distorted values in both distance and amplitude. In this paper we propose a method to acquire reliable distance information over the entire scene correcting each information based on the other data. The amplitude image is enhanced based on the depth values and this leads depth correction especially for far pixels.

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Iterative Attenuation Correction and Image Reconstruction Using Time-Of-Flight Positron Emission Tomography (양전자방출단층촬영기의 비행시간정보를 이용한 반복적 감쇠보정 및 영상재구성)

  • Lee, Nam-Yong
    • Journal of Korea Multimedia Society
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    • v.19 no.8
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    • pp.1371-1376
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    • 2016
  • In this paper, an iterative method is proposed to perform attenuation correction and image reconstruction simultaneously for positron emission tomography, by using the time-of-flight information. Numerical simulation results are presented to demonstrate an improved performance of the proposed method in attenuation correction and image reconstruction.

A Study on the Linetic Energy of the Laser-Ablated Cation Using Time-of-Flight Mass Spectrometry

  • 신동남;임훙선;정경훈
    • Bulletin of the Korean Chemical Society
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    • v.18 no.2
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    • pp.171-174
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    • 1997
  • The initial kinetic energy of laser-ablated Zn cation has been investigated via time-of-flight mass spectrometry. The flight times of the ions have been measured with a high voltage pulse on the extract electrode in the mass spectrometer, which has been delayed from the laser pulse. The time-of-flight equation including the initial kinetic energy term of the ion has been derived for the mass spectrometer. The optimum value of the initial kinetic energy has been extracted by fitting the measured flight times into the time-of-flight equation. The initial kinetic energy of the ions generated by Nd:YAG laser (532 nm) at the power density of 5 × 107 W/cm2 has been determined to be 22-44 kJ/mol.

Characterization of a Membrane Interface for Analysis of Air Samples Using Time-of-flight Mass Spectrometry

  • Jang, Yu-Mi;Oh, Jun-Sik;Park, Chang-Joon;Yang, Sang-Sik;Jung, Kwang-Woo
    • Bulletin of the Korean Chemical Society
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    • v.31 no.10
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    • pp.2791-2796
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    • 2010
  • In the present study, we constructed a membrane inlet assembly for selective permeation of volatile airborne organic compounds for subsequent analysis by time-of-flight mass spectrometry. The time-dependent diffusion of analytes through a $75\;{\mu}m$ thick polydimethylsiloxane membrane was measured by monitoring the ion signal after a step change in the sample concentration. The results fit well to a non-steady-state permeation equation. The diffusion coefficient, response time, and sensitivity were determined experimentally for a range of polar (halogenated) and nonpolar (aromatic) compounds. We found that the response times for several volatile organic compounds were greatly influenced by the alkyl chain length as well as the size of the substituted halogen atoms. The detection limits for benzene, ethylbenzene, and 2-propanol were 0.2 ppm, 0.1 ppm, and 3.0 ppm by volume, respectively, with a linear dynamic range greater than three orders of magnitude. These results indicate that the membrane inlet/time-of-flight mass spectrometry technique will be useful for a wide range of applications, particularly for in situ environmental monitoring.

Membrane Inlet-based Portable Time-of-flight Mass Spectrometer for Analysis of Air Samples

  • Kim, Tae-Kyu;Jung, Kyung-Hoon;Yoo, Seung-Kyo;Jung, Kwang-Woo
    • Bulletin of the Korean Chemical Society
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    • v.26 no.2
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    • pp.303-308
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    • 2005
  • A miniaturized time-of-flight mass spectrometer with an electron impact ionization source and sheet membrane introduction has been developed. The advantages and features of this mass spectrometer include high sensitivity, simple structure, low cost, compact volume with field portability, and ease of operation. A mass resolution of 400 at m/z 78 has been obtained with a 25 cm flight path length. Under optimized conditions, the detection limits for the volatile organic compounds (VOCs) studied were 0.2-10 ppm by volume with linear dynamic ranges greater than three orders of magnitude. The response times for various VOCs using a silicone membrane of 127 $\mu$m thickness were in the range 4.5-20 s, which provides a sample analysis time of less than 1 minute. These results indicate that the membrane introduction/time-of-flight mass spectrometer will be useful for a wide range of field applications, particularly for environmental monitoring.

Evaluation of Thickness Reduction in an Aluminum Sheet using SH-EMAT (SH-EMAT를 이용한 알루미늄 박판의 두께감육 평가)

  • Kim, Yong-Kwon;Park, Ik-Kuen
    • Journal of Welding and Joining
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    • v.28 no.2
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    • pp.74-78
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    • 2010
  • In this paper, a non-contact method of evaluating the thickness reduction in an aluminum sheet caused by corrosion and friction using SH-EMAT (shear horizontal, electromagnetic acoustic transducer) is described. Since this method is based on the measurement of the time-of-flight and amplitude change of guided waves caused from the thickness reduction, it provides information on the thinning defects. Information was obtained on the changes of the various wave features, such as their time-of-flight and amplitude, and their correlations with the thickness reduction were investigated. The interesting features in the dispersive behavior of selected guided modes were used for the detection of thinning defects. The measurements of these features using SH waves were performed on aluminum specimens with regions thinned by 7.2% to 29.5% of the total thickness. It is shown that the time-of-flight measurement provides an estimation of the thickness reduction and length of the thinning defects.