• Title/Summary/Keyword: non-destructive method

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Time dependent numerical simulation of MFL coil sensor for metal damage detection

  • Azad, Ali;Lee, Jong-Jae;Kim, Namgyu
    • Smart Structures and Systems
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    • v.28 no.6
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    • pp.727-735
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    • 2021
  • Recently, non-destructive health monitoring methods such as magnetic flux leakage (MFL) method, have become popular due to their advantages over destructive methods. Currently, numerical study on this field has been limited to simplified studies by only obtaining MFL instead of induced voltage inside coil sensor. In this study, it was proposed to perform a novel numerical simulation of MFL's coil sensor by considering vital parameters including specimen's motion with constant velocity and saturation status of specimen in time domain. A steel-rod specimen with two stepwise cross-sectional changes (i.e., 21% and 16%) was fabricated using low carbon steel. In order to evaluate the results of numerical simulation, an experimental test was also conducted using a magnetic probe, with same size specimen and test parameters, exclusively. According to comparative results of numerical simulation and experimental test, similar signal amplitude and signal pattern were observed. Thus, proposed numerical simulation method can be used as a reliable source to check efficiency of sensor probe when different size specimens with different defects should be inspected.

Determination of Regression Model for Estimating Root Fresh Weight Using Maximum Leaf Length and Width of Root Vegetables Grown in Reclaimed Land (간척지 재배 근채류의 최대 엽장과 엽폭을 이용한 지하부 생체중 추정용 회귀 모델 결정)

  • Jung, Dae Ho;Yi, Pyoung Ho;Lee, In-Bog
    • Korean Journal of Environmental Agriculture
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    • v.39 no.3
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    • pp.204-213
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    • 2020
  • BACKGROUND: Since the number of crops cultivated in reclaimed land is huge, it is very difficult to quantify the total crop production. Therefore, a non-destructive method for predicting crop production is needed. Salt tolerant root vegetables such as red beets and sugar beet are suitable for cultivation in reclaimed land. If their underground biomass can be predicted, it helps to estimate crop productivity. Objectives of this study are to investigate maximum leaf length and weight of red beet, sugar beet, and turnips grown in reclaimed land, and to determine optimal model with regression analysis for linear and allometric growth models. METHODS AND RESULTS: Maximum leaf length, width, and root fresh weight of red beets, sugar beets, and turnips were measured. Ten linear models and six allometric growth models were selected for estimation of root fresh weight and non-linear regression analysis was conducted. The allometric growth model, which have a variable multiplied by square of maximum leaf length and maximum leaf width, showed highest R2 values of 0.67, 0.70, and 0.49 for red beets, sugar beets, and turnips, respectively. Validation results of the models for red beets and sugar beets showed the R2 values of 0.63 and 0.65, respectively. However, the model for turnips showed the R2 value of 0.48. The allometric growth model was suitable for estimating the root fresh weight of red beets and sugar beets, but the accuracy for turnips was relatively low. CONCLUSION: The regression models established in this study may be useful to estimate the total production of root vegetables cultivated in reclaimed land, and it will be used as a non-destructive method for prediction of crop information.

A Study for Automatic Analysis of Qualysis of Quality Components in Tabacco Leaves Using Non-destructive Analytical Method (근적외 분광분석법에 의한 잎담배의 품질측정 자동화)

  • Cho, Rae-Kwang;Lee, Kyung-Hee;Lee, Jung-Hwan;Kwon, Yong-Kil
    • Applied Biological Chemistry
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    • v.37 no.5
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    • pp.349-355
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    • 1994
  • The present study was conducted to develop the automatic analytical method for determining moisture, nicotine, reducing sugar and total nitrogen contents and color(L, a, b) value in domestic tobacco leaves using near infrared(NIR) spectroscopy. The results of multiple linear regression analysis between chemical and NIR data showed that NIR spectro-scopy can determine those quality components of tobacco samples in 30 seconds, non-destructively. The results using developed calibrations are summarized as follows; The standard error of prediction(SEP) for moisture, nicotine. total nitrogen, reducing sugar contents and color(L, a, b) value in domestic tobacco leaves was 0.28%, 0.25%, 0.07%, 0.75%, 1.25, 0.44 and 1.07, respectively. In addition, The possibility of developing the cheaper filter type NIR instrument, for quality evaluation in the procurement from leaf tobacco cultivators and process control was investigated.

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Comparison of X-ray computed tomography and magnetic resonance imaging to detect pest-infested fruits: A pilot study

  • Kim, Taeyun;Lee, Jaegi;Sun, Gwang-Min;Park, Byung-Gun;Park, Hae-Jun;Choi, Deuk-Soo;Ye, Sung-Joon
    • Nuclear Engineering and Technology
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    • v.54 no.2
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    • pp.514-522
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    • 2022
  • Non-destructive testing (NDT) technology is a widely used inspection method for agricultural products. Compared with the conventional inspection method, there is no extensive sample preparation for NDT technology, and the sample is not damaged. In particular, NDT technology is used to inspect the internal structure of agricultural products infested by pests. The introduction and spread of pests during the import and export process can cause significant damage to the agricultural environment. Until now, pest detection in agricultural products and quarantine processes have been challenging because they used external inspection methods. However, NDT technology is advantageous in these inspection situations. In this pilot study, we investigated the feasibility of X-ray computed tomography (X-ray CT) and magnetic resonance imaging (MRI) to identify pest infestation in agricultural products. Three kinds of artificially pest-infested fruits (mango, tangerine, and chestnut) were non-destructively inspected using X-ray CT and MRI. X-ray CT was able to identify all pest infestations in fruits, while MRI could not detect the pest-infested chestnut. In addition, X-ray CT was superior to the quarantine process than MRI based on the contrast-to-noise ratio (CNR), image acquisition time, and cost. Therefore, X-ray CT is more appropriate for the pest quarantine process of fruits than MRI.

Energy Spectrum Measurement of High Power and High Energy (6 and 9 MeV) Pulsed X-ray Source for Industrial Use

  • Takagi, Hiroyuki;Murata, Isao
    • Journal of Radiation Protection and Research
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    • v.41 no.2
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    • pp.93-99
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    • 2016
  • Background: Industrial X-ray CT system is normally applied to non-destructive testing (NDT) for industrial product made from metal. Furthermore there are some special CT systems, which have an ability to inspect nuclear fuel assemblies or rocket motors, using high power and high energy (more than 6 MeV) pulsed X-ray source. In these case, pulsed X-ray are produced by the electron linear accelerator, and a huge number of photons with a wide energy spectrum are produced within a very short period. Consequently, it is difficult to measure the X-ray energy spectrum for such accelerator-based X-ray sources using simple spectrometry. Due to this difficulty, unexpected images and artifacts which lead to incorrect density information and dimensions of specimens cannot be avoided in CT images. For getting highly precise CT images, it is important to know the precise energy spectrum of emitted X-rays. Materials and Methods: In order to realize it we investigated a new approach utilizing the Bayesian estimation method combined with an attenuation curve measurement using step shaped attenuation material. This method was validated by precise measurement of energy spectrum from a 1 MeV electron accelerator. In this study, to extend the applicable X-ray energy range we tried to measure energy spectra of X-ray sources from 6 and 9 MeV linear accelerators by using the recently developed method. Results and Discussion: In this study, an attenuation curves are measured by using a step-shaped attenuation materials of aluminum and steel individually, and the each X-ray spectrum is reconstructed from the measured attenuation curve by the spectrum type Bayesian estimation method. Conclusion: The obtained result shows good agreement with simulated spectra, and the presently developed technique is adaptable for high energy X-ray source more than 6 MeV.

Program Development for Material Degradation Evaluation Using Grain Boundary Etching Method (입계부식법을 이용한 열화도 평가 프로그램 개발)

  • Yu, Hyo-Seon;Baek, Seung-Se;Na, Seong-Hun;Kim, Jeong-Gi;Lee, Hae-Mu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.7
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    • pp.1064-1072
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    • 2001
  • It is very important to evaluate material degradation like temper and carbide embrittlements to secure the reliable and efficient operational conditions and to prevent brittle failure in service. The extent of material deterioration can be accurately evaluated by mechanical test such as impact test or creep test. But it is almost impossible to sample a large specimen from in-service plants. Thus, the material degradation evaluation by a non-destructive method is earnestly required. Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However the program for material degradation evaluation using the grain boundary etching method(GEM) in Windows 98 domain doesnt be developed now. The aims of this paper are to develop the program and to complete the new master curve equations for the evaluation of material degradation on in-serviced high temperature components.

The Measurement Method of Small Deformation by using Holographic Interferometry (홀로그래픽 산섭법을 이용한 미소변형 측정법)

  • 강영준;문상준;최장섭
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.10a
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    • pp.273-278
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    • 1993
  • Conventional measurement methods for non-destructive testing(NDT) in nuclear power plants other industrial plants have been performed as the methods of contact with objects to be inspect, but those methods have been taken relatively much time to be inspected. Holographic interferometry which is a non-contact optical measurement method using a coherent light can overcome these demerit, and also has an advantage that the quantitative measurement of small deformation for large areas can be accomplished at a time with high precision. In this paper the comparisons of the experimental results from holographic interferometry with those form the finite element method(FEM) and the analytical solutions of elastic equation are discussed.

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An Algorithm for the Characterization of Surface Crack by Use of Dipole Model and Magneto-Optical Non-Destructive Inspection System

  • Lee, Jin-Yi;Lyu, Sung-Ki;Nam, Young-Hyun
    • Journal of Mechanical Science and Technology
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    • v.14 no.10
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    • pp.1072-1080
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    • 2000
  • Leakage magnetic flux (LMF) is widely used for non-contact detection of cracks. The combination of optics and LMF offers advantages such as real time inspection, elimination of electrical noise, high spatial resolution, etc. This paper describes a new nondestructive evaluation method based on an original magneto-optical inspection system, which uses a magneto-optical sensor, LMF, and an improved magnetization method. The improved magnetization method has the following characteristics: high observation sensitivity, independence of the crack orientation, and precise transcription of the geometry of a complex crack. The use of vertical magnetization enables the visualization of the length and width of a crack. The inspection system provides the images of the crack, and shows a possibility for the computation of its depth.

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Determination of Mode Dispersion Curves of Surface Wave Using HWAW Method (HWAW(Harmonic Wavelet Analysis of Wave)방법을 이용한 표면파 모드 분산곡선의 결정)

  • Park, Hyung-Choon;Kim, Dong-Soo;Bang, Eun-Seok
    • Journal of the Korean Geotechnical Society
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    • v.22 no.12
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    • pp.15-24
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    • 2006
  • The evaluation of shear modulus is very important in various fields of civil engineering. Non-destructive seismic methods can be used to determine shear wave velocity ($V_s$) profile. Non-destructive seismic methods geneally consist of three steps: field testing, evaluation of dispersion curve, and determination of Vs profile by inversion process. Non-destructive seismic methods can be divided into two categories according to the number of receivers used for data reduction: two-channel tests and multi-channel tests. Two channel tests use apparent velocity dispersion curve and multi-channel tests use mode dispersion curves. Multi-channel tests using mode dispersion curve can reduce calculation time to determine soil profile and uncertainties in inversion process. So far, only multi-channel tests can determine mode dispersion curves but multi-channel test needs many receivers to determine reasonable mode dispersion curves. In this paper, HWAW (Harmonic Wavelet Analysis of Wave) method is applied to determine mode dispersion curves. HWAW method uses short test setup which consists of two receivers with a spacing of 1 to 3 m. Through numerical simulations and field application, it is shown that HWAW can determine resonable mode disperson curves.

Estimation of the Number of Physical Flaws Using Effective POD (유효 POD를 이용한 물리적 결함 수의 추정)

  • Lee, Jae-Bong;Park, Jae-Hak;Kim, Hong-Deok;Chung, Han-Sub
    • Journal of the Korean Society of Safety
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    • v.21 no.4 s.76
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    • pp.42-48
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    • 2006
  • The strategies of maintenance and operation are usually established based on the number of flaws and their size distribution obtained from nondestructive inspection in order to preserve safety of the plant. But non destructive inspection results are different from the physical flaws which really exist in the equipments. In case of a single inspection, it is easy to estimate the number of physical flaws using the POD curve. However, we may be faced with some difficulties in obtaining the number of physical flaws from the periodic in-service non destructive inspection data. In this study a simple method for estimating the number of physical flaws from periodic in-service nondestructive inspection data was proposed. In order to obtain the flaw growth history, the flaw growth was simulated using the Monte Carlo method and the flaw size and the corresponding POD value were obtained for each flaw at each periodic inspection time. The flaw growth rate used in the simulation was statistically calculated from the in-service inspection data. By repeating the simulation numerous flaw growth data could be generated and the effective POD curve was obtained as a function of flaw size. From the effective POD curve the number of physical flaws was obtained. The usefulness and convenience of the proposed method was evaluated from several applications and satisfactory results were obtained.