• Title/Summary/Keyword: dicA

Search Result 221, Processing Time 0.026 seconds

Application of Digital Image Correlations (DIC) Technique on Geotechnical Reduced-Scale Model Tests

  • Tong, Bao;Yoo, Chungsik
    • Journal of the Korean Geosynthetics Society
    • /
    • v.21 no.1
    • /
    • pp.33-48
    • /
    • 2022
  • This paper presents illustrative examples of the application of advanced digital image correlation (DIC) technology in the geotechnical laboratory tests, such as shallow footing test, trapdoor test, retaining wall test, and wide width tensile test on geogrid. The theoretical background of the DIC technique is first introduced together with fundamental equations. Relevant reduced-scale model tests were then performed using standard sand while applying the DIC technique to capture the movement of target materials during tests. A number of different approaches were tried to obtain optimized images that allow efficient tracking of material speckles based on the DIC technique. In order to increase the trackability of soil particles, a mix of dyed and regular sand was used during the model tests while specially devised painted speckles were applied to the geogrid. A series of images taken during tests were automatically processed and analyzed using software named VIC-2D that automatically generates displacements and strains. The soil deformation field and associated failure patterns obtained from the DIC technique for each test were found to compare fairly well with the theoretical ones. Also shown is that the DIC technique can also general strains appropriate to the wide width tensile test on geogrid, It is demonstrated in this study that the advanced DIC technique can be effectively used in monitoring the deformation and strain field during a reduced-scale geotechnical model laboratory test.

2D Image Numerical Correction Method for 2D Digital Image Correlation (2차원 DIC 기법 적용을 위한 2D 이미지 보정 수치 해석 기법)

  • Kim, Wonseop;Hong, Seokmoo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.18 no.4
    • /
    • pp.391-397
    • /
    • 2017
  • Recently, digital image correlation (DIC) techniques have been used to measure dynamic deformation during tensile testing. The standard tensile test method measures the average displacement of the relevant specimen to calculate the true stress-strain curve. Therefore, the validity of the true stress curve is restricted to the stress incurred within the uniform stretching interval, i.e., the maximum stress corresponds to the starting point of the necking deformation. Alternatively, if DIC is used, the effective range of the strain and strain rate can be extended to the breaking point of the tensile specimen, because of the feasibility of measuring the local strain over the entire area of interest. Because of these advantages, many optical 3D measurement systems have been introduced and used in research and industry. However, the conventional 3D measurement systems are exceedingly expensive and time consuming. In addition, these systems have the disadvantage of a very large equipment size which makes their transport difficult. In this study, a 2D image correction method employing a 2D DIC measurement method in conjunction with a numerical analysis method is developed using a smartphone. The results of the proposed modified 2D DIC method yielded higher accuracy than that obtained via the 3D measurement equipment. In conclusion, it was demonstrated that the proposed 2D DIC and calibration methods yield accurate measurement results with low time costs.

Comparing Financial Portfolios and Housing Wealth Effects of Single Income and Dual Income Couples (외벌이와 맞벌이 부부가구의 자산포트폴리오 특성 및 주택자산효과 차이 비교)

  • Lee, Hyunjeong
    • Journal of the Korean housing association
    • /
    • v.27 no.6
    • /
    • pp.95-104
    • /
    • 2016
  • The purpose of this research is to compare housing wealth effects of home-owning single income couples (SIC) and dual income couples (DIC) on their non-durable consumption and to assess the effects by location, age groups, housing structure type, debt-to-asset ratio and employment status. Using the Korean Labor and Income Panel Study (KLIPS) of 2014, this empirical study identified 1,198 SIC households and 1,044 DIC households, and employed multiple regression analysis. The main results reveal that the difference of financial portfolios between SIC and DIC households was little but housing wealth effects were stronger among SIC households than DIC counterpart. It's evident that housing wealth effects were conspicuous for SIC and DIC households who were headed by wage earners aged over 40s, and resided in apartment outside the Seoul Metropolitan Area. However, household debt became a determinant in contradicting housing wealth effects of SIC and DIC households. While the household financial dimension was in proportion to income, DIC households didn't gain much financial security due to increasing expenditure. Further, this research imply that liquidity constraints explicitly posed a more serious threat to SIC households whose dependence on housing asset is larger than their counterpart.

Variation Pattern of ${\delta}^{13}C_{DIC}$ of the Odaecheon Stream Water

  • Shin, Woo-Jin;Chung, Gong-Soo
    • 한국지구과학회:학술대회논문집
    • /
    • 2005.02a
    • /
    • pp.115-125
    • /
    • 2005
  • Carbon isotopic composition of a stream (Odaecheon Stream) monitored over 7 months from July 2004 to January 2005 in Gangweon Province ranges from -9.24 to -4.69‰. Strong negative correlation between ${\delta}^{13}C_{DIC}$ and water temperature suggests that temperature is a dominant factor controlling ${\delta}^{13}C_{DIC}$ in the Odaecheon Stream. The variation pattern of ${\delta}^{13}C_{DIC}$ was thought to be caused by fractionation of C isotope between stream water and atmosphere and more fractionation at reduced temperature. More fractionation of C isotope between stream water and atmosphere at reduced temperature resulted in increase of ${\delta}^{13}C_{DIC}$ of stream water in winter compared to summer. Photosynthesis and respiration of aqueous biota seem to affect little in ${\delta}^{13}C_{DIC}$ as indicated by little variation of dissolved oxygen and reverse variation pattern of Eh in the stream and scarce aqueous biota in stream water. pH seems to be controlled by $CO_2{2}$ exchange between stream water and atmosphere. During summer more $CO_2{2}$ exchange between stream water and atmosphere resulted in decrease in pH value.

  • PDF

Measuring displacements of a railroad bridge using DIC and accelerometers

  • Hoag, Adam;Hoult, Neil A.;Take, W. Andy;Moreu, Fernando;Le, Hoat;Tolikonda, Vamsi
    • Smart Structures and Systems
    • /
    • v.19 no.2
    • /
    • pp.225-236
    • /
    • 2017
  • Railroad bridges in North America are an integral but aging part of the railroad network and are typically only monitored using visual inspections. When quantitative information is required for assessment, railroads often monitor bridges using accelerometers. However without a sensor to directly measure displacements, it is difficult to interpret these results as they relate to bridge performance. Digital Image Correlation (DIC) is a non-contact sensor technology capable of directly measuring the displacement of any visible bridge component. In this research, a railroad bridge was monitored under load using DIC and accelerometers. DIC measurements are directly compared to serviceability limits and it is observed that the bridge is compliant. The accelerometer data is also used to calculate displacements which are compared to the DIC measurements to assess the accuracy of the accelerometer measurements. These measurements compared well for zero-mean lateral data, providing measurement redundancy and validation. The lateral displacements from both the accelerometers and DIC at the supports were then used to determine the source of lateral displacements within the support system.

Evaluation of Volatile Organic Compounds Levels in Industrial Complex and Nearby Residential Areas of Daegu (대구지역 공단과 인근 주거지역의 휘발성유기화합물질 오염도 평가)

  • Jo, Wan Geun;Lee, Jin U
    • Journal of Environmental Science International
    • /
    • v.13 no.6
    • /
    • pp.519-525
    • /
    • 2004
  • Air pollution from the Daegu industrial complex (Die) in Korea has been a common nuisance and cause of complaints for nearby residents. The current study measured the indoor and outdoor levels of six VOC (benzene, toluene, ethylbenzene, and three isomeric xylenes) at two residential areas with a different proximity to the ODIC, plus the ambient levels at two industrial areas within the boundary of the DDIC. The QA/QC program included the range of correlation coefficient (0.94-0.99) for calibration curves, within the permissible range. Toluene was the most abundant VOC in the ambient air both in residential and industrial areas. Both indoor and outdoor air concentrations of all target VOC except benzene were higher in residential area near the DIC compared to that further away from the DIC. Moreover, the ambient air concentrations of all target VOC except benzene for two industrial sites (A and B) were significantly higher than the outdoor or indoor air concentrations in the two residential areas. The findings further suggested that VOC ambient levels measured in a residential area near the DIC be used as a potential indicator of odor-causing unidentified air pollutants transported from the DIC. Moreover, it was found that the elevated ambient toluene levels outweighed the indoor sources with respect to the environmental exposure of residents nearby the DIC. However, in the residential area further away from the DIC, the toluene indoor sources outweighed the outdoor sources.

Application of Digital Image Correlation Method for Measurement of Rock Pillar Displacement and Vibration Due to Underground Mine Blasting (지하 광산발파에 따른 암반광주의 변위 및 진동 측정을 위한 이미지 영상 상관법 적용연구)

  • Ko, Young-Hun;Seo, Seung-Hwan;Lim, Hyun-Sung;Jin, Tai-Lie;Chung, Moon-Kyung
    • Explosives and Blasting
    • /
    • v.37 no.4
    • /
    • pp.1-9
    • /
    • 2019
  • In this study the applicability of a Digital Image Correlation (DIC) method was investigated by measuring the displacement and vibration of rock pillar due to underground mining blasting. When combined with a high speed photography technology, the DIC method provides an excellent photographic image processing ability that can be used to convert the evolving full-field surface properties of structures to 2D or 3D set of coordinate values. The measured coordinate sets are then used to calculate the displacement, strain, and velocity of the target structure. This technique is widely used in science and engineering, and continuously finds its new application areas. In this study, the DIC system and the conventional seismograph were compared for their ability to measure the displacement and vibration produced by blasting. In the field test both methods showed similar results. Thus, it is concluded that the DIC method is feasible to measure the ground displacements and vibrations from blasting.

QR code as speckle pattern for reinforced concrete beams using digital image correlation

  • Krishna, B. Murali;Tezeswi, T.P.;Kumar, P. Rathish;Gopikrishna, K.;Sivakumar, M.V.N.;Shashi, M.
    • Structural Monitoring and Maintenance
    • /
    • v.6 no.1
    • /
    • pp.67-84
    • /
    • 2019
  • Digital Image Correlation technique (DIC) is a non-contact optical method for rapid structural health monitoring of critical infrastructure. An innovative approach to DIC is presented using QR (Quick Response) code based random speckle pattern. Reinforced Cement Concrete (RCC) beams of size $1800mm{\times}150mm{\times}200mm$ are tested in flexure. DIC is used to extract Moment (M) - Curvature (${\kappa}$) relationships using random speckle patterns and QR code based random speckle patterns. The QR code based random speckle pattern is evaluated for 2D DIC measurements and the QR code speckle pattern performs satisfactorily in comparison with random speckle pattern when considered in the context of serving a dual purpose. Characteristics of QR code based random speckle pattern are quantified and its applicability to DIC is explored. The ultimate moment-curvature values computed from the QR code based random speckled pattern are found to be in good agreement with conventional measurements. QR code encrypts the structural information which enables integration with building information modelling (BIM).

Tensile Tests for Copper Thin Foils by Using DIC Method (DIC 법을 이용한 구리박막의 인장시험)

  • Kim, Chung Youb;Song, Ji Ho;Park, Kyung Jo
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.36 no.12
    • /
    • pp.1529-1534
    • /
    • 2012
  • In this study, tensile tests for 12-${\mu}m$-thick copper thin foils were performed by using the DIC method. The DIC method provided precise stress-strain curves for thin film materials, and a commercial inkjet printer can be simply and effectively used for printing speckle patterns on the specimen of Cu thin films whose surface contrast is too low to apply the DIC method. The mechanical properties of Cu thin foils obtained in this study are as follows: elastic modulus E = 89.2 GPa, 0.2% offset yield stress $S_{0.2%}$= 232.8 MPa, tensile strength $S_u$= 319.2 MPa, elongation at fracture ${\varepsilon}_f$=16.8 %, and Poisson's ratio ${\nu}$= 0.34.

Stereo-digital image correlation in the behavior investigation of CFRP-steel composite members

  • Dai, Yun-Tong;Wang, Hai-Tao;Ge, Tian-Yuan;Wu, Gang;Wan, Jian-Xiao;Cao, Shuang-Yin;Yang, Fu-Jun;He, Xiao-Yuan
    • Steel and Composite Structures
    • /
    • v.23 no.6
    • /
    • pp.727-736
    • /
    • 2017
  • The application of carbon fiber reinforced polymer (CFRP) in steel structures primarily includes two categories, i.e., the bond-critical application and the contact-critical application. Debonding failure and buckling failure are the main failure modes for these two applications. Conventional electrometric techniques may not provide precise results because of the limitations associated with single-point contact measurements. A nondestructive full-field measurement technique is a valuable alternative to conventional methods. In this study, the digital image correlation (DIC) technique was adopted to investigate the bond behavior and buckling behavior of CFRP-steel composite members. The CFRP-to-steel bonded joint and the CFRP-strengthened square hollow section (SHS) steel column were tested to verify the suitability of the DIC technique. The stereo-DIC technique was utilized to measure continuous deformation. The bond-slip relationship of the CFRP-to-steel interface was derived using the DIC data. Additionally, a multi-camera DIC system consisting of four stereo-DIC subsystems was proposed and applied to the compressive test of CFRP-strengthened SHS steel column. The precise buckling location and CFRP delamination of the CFRP-strengthened SHS steel column were identified. The experimental results confirm that the stereo-DIC technique can provide effective measurements for investigating the behaviors of CFRP-steel composite members.