• Title, Summary, Keyword: testing and calibration

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Development of Calibration System for Contact Transducer (초음파 탐촉자의 교정 시스템 개발)

  • Nam, Y.H.;Seong, U.H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.19 no.4
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    • pp.294-299
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    • 1999
  • In this paper, the calibration system for contact transducer has been developed to improve the reliability of the inspection result of ultrasonic testing on rotors. This system consists of signal processing parts: (oscilloscope, spectrum analyzer, pulser/receiver), standard block, and user interface program. Signal processing for the calibration system was performed quickly with high accuracy. The developed system has been applied to a practical calibration of probe using the non-destructive testing on rotors, and demonstrated high sensitivity and precision.

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Experimental method and evaluation of the calibration capability for the national calibration centers using the platinum resistance temperature sensors (백금저항온도센서를 이용한 국가교정기관의 교정능력 평가 및 실험방법)

  • Gam, Kee-Sool;Yoo, Sung-Ho;Kim, Sung-Min;Lee, In-Sick
    • Journal of Sensor Science and Technology
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    • v.14 no.4
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    • pp.231-236
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    • 2005
  • Calibration capability was evaluated using the reference-grade platinum resistance thermometer (PRT) in the temperature range of $-50^{\circ}C$ to $250^{\circ}C$ for the national calibration centers. The reference-grade PRT was calibrated at the several fixed points, which was composed by the freezing points of Sn, In, the melting point of Ga and the triple point of water and Hg, before and after the round-robin test (RRT) experiments. The temperature scale of reference-grade PRT was compared to the local standard PRT's using the system of the national calibration centers. $E_{n}$ values was calculated by the temperature difference between the reference-grade PRT and the local standard PRT, and the best measurement capability. Finally, the capability of the national calibration centers was evaluated by the $E_{n}$ values.

Level Calibration of Ultrasonic Nondestructive Testing Considering Flaw Position (불연속부의 위치를 고려한 초음파비파괴검사 등급보정)

  • Shin, Byoung-Chul;Song, Ho-San;Jeong, Hwa-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.5 no.4
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    • pp.155-160
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    • 2001
  • KS-code(KS B 0896) for nondestructive ultrasonic testing classifies the quality level by relative flaw size only. But flaw position is more important than the flaw size. Test blocks having artificial holes near surface show lower yield load than the blocks having deeply located holes from the surface. So, level calibration table was proposed for classifying the quality level of welded steel structures.

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A Study for the Effect on the Uncertainty of Power Performance Testing of Windturbine by a Site Calibration (Site calibration이 풍력발전시스템 성능시험 불확도에 미치는 영향 연구)

  • Kim, Keon-Hoon;Hyun, Seung-Gun
    • Journal of the Korean Solar Energy Society
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    • v.31 no.2
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    • pp.107-112
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    • 2011
  • A comparison study between two performance testing results, one is on the site calibration not needed and the other is needed, was proceeded for the understanding on the effect of site calibration on the complex terrain. As a result, it is revealed that all of uncertainty components is effected by the topographical features dramatically. And the maximum difference of uncertainty reached at around 8% of rated capacity of wind turbine. So, the site calibration is an effective method to remove the variable wind effect by the ground complexity and must be proceeded before the power performance testing of a wind turbine.

Application of Bender Element Tests for the Estimation of Maximum shear Modulus in Calibration Chamber (모형 지반의 최대 전단탄성계수 평가를 위한 벤더 엘리먼트 시험의 적용)

  • Kwon, Hyung-Min;Ko, Young-Ju;Chung, Choong-Ki
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1278-1284
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    • 2008
  • This study carried out bender element tests in a calibration chamber in order to estimate the characteristics of soil specimen prepared in a calibration chamber. Basically, the purpose of bender element test is to measure the shear wave velocity. Bender element test cannot only confirm the status of soil specimen deposited in a chamber, but also estimate the consolidation process indirectly. In order to carry out bender element test in a calibration chamber, a pair of bender elements was installed inside the chamber, using the 'ㄷ' shaped frame. For the sandy soils having various relative densities in various stress conditions, the maximum shear modulus was estimated. From the comparison with bender element test results in a triaxial testing device, testing device and procedure was validated.

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Testing and Self Calibration of RF Circuit using MEMS Switches

  • Kannan, Sukeshwar;Kim, Bruce;Noh, Seok-Ho;Park, Se-Hyun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.882-885
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    • 2011
  • This paper presents testing and self-calibration of RF circuits using MEMS switches to identify process-related defects and out of specification circuits. We have developed a novel multi-tone dither test technique where the test stimulus is generated by modulating the RF carrier signal with a multi-tone signal generated using an Arbitrary Waveform Generator (AWG) with additive white Gaussian noise. This test stimulus is provided as input to the RF circuit and peak-to-average ratio (PAR) is measured at the output. For a faulty circuit, a significant difference is observed in the value of PAR as compared to a fault-free circuit. Simulation is performed for various circuit conditions such as fault-free as well as fault-induced and their corresponding PARs are stored in the look-up table. This testing and self-calibration technique is exhaustive and efficient for present-day communication systems.

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Self-Calibration of High Frequency Errors of Test Optics by Arbitrary N-step Rotation

  • Kim, Seung-Woo;Rhee, Hyug-Gyo
    • International Journal of Precision Engineering and Manufacturing
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    • v.1 no.2
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    • pp.115-123
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    • 2000
  • We propose an extended version of multi-step algorithm of self-calibration of interferometric optical testing instruments. The key idea is to take wavefront measurements with near equal steps in that a slight angular offset is intentionally provided in part rotation. This generalized algorithm adopts least squares technique to determine the true azimuthal positions of part rotation and consequently eliminates calibration errors caused by rotation inaccuracy. In addition, the required numbers of part rotation is greatly reduced when higher order spatial frequency terms are of particular importance.

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Study of statistical distribution for four-port TEM cell

  • Jeon, Sangbong;Kwon, Jong-Hwa
    • Journal of Multimedia Information System
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    • v.1 no.2
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    • pp.127-132
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    • 2014
  • The transverse electromagnetic (TEM) cells are widely used for electromagnetic compatibility (EMC) testing and field probe calibrations. We propose the verification of TEM mode with statistical method using a four-port TEM cell. The verification results are compared with Normal, Rayleigh, and Gamma distribution. As a result, the 75 % quantile of the Rayleigh distribution is excellent agreement with the true quantiles for a number of calibration points.

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Development of Calibration Target for Infrared Thermal Imaging Camera (적외선 열화상 카메라용 캘리브레이션 타겟 개발)

  • Kim, Su Un;Choi, Man Yong;Park, Jeong Hak;Shin, Kwang Yong;Lee, Eui Chul
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.3
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    • pp.248-253
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    • 2014
  • Camera calibration is an indispensable process for improving measurement accuracy in industry fields such as machine vision. However, existing calibration cannot be applied to the calibration of mid-wave and long-wave infrared cameras. Recently, with the growing use of infrared thermal cameras that can measure defects from thermal properties, development of an applicable calibration target has become necessary. Thus, based on heat conduction analysis using finite element analysis, we developed a calibration target that can be used with both existing visible cameras and infrared thermal cameras, by implementing optimal design conditions, with consideration of factors such as thermal conductivity and emissivity, colors and materials. We performed comparative experiments on calibration target images from infrared thermal cameras and visible cameras. The results demonstrated the effectiveness of the proposed calibration target.