• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.372-380
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• 2012

The optical method Digital Speckle Correlation Measurement (DSCM) has been extensively applied due its capability to measure the entire displacement field over a body surface. A formula of displacement measurement errors by the gradient-based DSCM method was derived. The errors were found to explicitly relate to the image grayscale errors consisting of sub-pixel interpolation algorithm errors, image noise, and subset deformation mismatch at each point of the subset. A power-law dependence of the standard deviation of displacement measurement errors on the subset size was established when the subset deformation was rigid body translation and random image noise was dominant and it was confirmed by both the numerical and experimental results. In a gradient-based algorithm the basic assumption is rigid body translation of the interrogated subsets, however, this is in contradiction to the real circumstances where strains exist. Numerical and experimental results also indicated that, subset shape function mismatch was dominant when the order of the assumed subset shape function was lower than that of the actual subset deformation field and the power-law dependence clearly broke down. The power-law relationship further leads to a simple criterion for choosing a suitable subset size, image quality, sub-pixel algorithm, and subset shape function for DSCM.

• Coupled systems mechanics
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• 제11권1호
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• pp.15-32
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• 2022

The comprehensive understanding of the fiber reinforced polymer behavior requires the use of advanced non-destructive testing methods due to its heterogeneous microstructure and anisotropic mechanical proprieties. In addition, the material response under load is strongly associated with manufacturing defects (e.g., voids, inclusions, fiber misalignment, debonds, improper cure and delamination). Such imperfections and microstructures induce various damage mechanisms arising at different scales before macrocracks are formed. The origin of damage phenomena can only be fully understood with the access to underlying microstructural features. This makes X-ray Computed Tomography an appropriate imaging tool to capture changes in the bulk of fibrous materials. Moreover, Digital Volume Correlation (DVC) can be used to measure kinematic fields induced by various loading histories. The correlation technique relies on image contrast induced by microstructures. Fibrous composites can be reinforced by different fiber architectures that may lead to poor natural contrast. Hence, a priori analyses need to be performed to assess the corresponding DVC measurement uncertainties. This study aimed to evaluate measurement resolutions of global and regularized DVC for glass fiber reinforced polymers with different fiber architectures. The measurement uncertainties were evaluated with respect to element size and regularization lengths. Even though FE-based DVC could not reach the recommended displacement uncertainty with low spatial resolution, regularized DVC enabled for the use of fine meshes when applying appropriate regularization.

• 한국전자파학회논문지
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• 제29권7호
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• pp.491-499
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• 2018

잡음지수분석기의 일반적인 교정방법은 잡음전원을 이용하는 방법이다. 이 방법은 교정 시 잡음전원과 잡음지수분석기의 부정합을 고려하지 않기 때문에 측정결과에서 심각한 불규칙 리플을 동반한다. 본 논문에서는 잡음전원과 잡음지수분석기의 부정합을 모두 고려한 새로운 잡음지수분석기의 교정 및 이를 이용한 새로운 잡음상관행렬 측정방법을 제안한다. 제안하는 방법은 uncorrected 잡음전력을 이용, 교정하지 않은 잡음지수분석기의 이득과 잡음상관행렬을 결정하였다. 그리고 결정된 이득과 잡음상관행렬을 이용, DUT에 대한 잡음상관행렬 측정결과에서 잡음지수분석기의 영향을 교정하였다. 제안된 방법을 통해, 측정된 DUT의 잡음파라미터는 상대적인 잡음비를 이용한 측정 결과와 같은 정도의 불규칙 리플을 보였다.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.173-178
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• 2016

Background: In situ gamma spectrometry has been used to measure environmental radiation, assumptions are usually made about the depth distribution of the radionuclides of interest in the soil. The main limitation of in situ gamma spectrometry lies in determining the depth distribution of radionuclides. The objective of this study is to develop a method for subsurface characterization by in situ measurement. Materials and Methods: The peak to valley method based on the ratio of counting rate between the photoelectric peak and Compton region was applied to identify the depth distribution. The peak to valley method could be applied to establish the relation between the spectrally derived coefficients (Q) with relaxation mass per unit area (${\beta}$) for various depth distribution in soil. The in situ measurement results were verified by MCNP simulation and calculated correlation equation. In order to compare the depth distributions and contamination levels in decommissioning KRR site, in situ measurement and sampling results were compared. Results and Discussion: The in situ measurement results and MCNP simulation results show a good correlation for laboratory measurement. The simulation relationship between Q and source burial for the source layers have exponential relationship for a variety depth distributions. We applied the peak to valley method to contaminated decommissioning KRR site to determine a depth distribution and initial activity without sampling. The observed results has a good correlation, relative error between in situ measurement with sampling result is around 7% for depth distribution and 4% for initial activity. Conclusion: In this study, the vertical activity distribution and initial activity of $^{137}Cs$ could be identifying directly through in situ measurement. Therefore, the peak to valley method demonstrated good potential for assessment of the residual radioactivity for site remediation in decommissioning and contaminated site.

• 대한치과보철학회지
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• 제44권3호
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• pp.314-324
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• 2006

Statement of problem. Osseointegration is important mechanism of dental implant but it is not easy to evaluate. Indirect measurement is non-invasive and clinically applicable but they need more study about correlation between indirect values and degree of osseointegration. Purpose. The aims of this study were to evaluate the coefficient of correlation between indirect measurement and direct measurement under different healing time, and assessment of effect of initial insertion torque to the implant stability. Material and Methods. 20 rabbits received 3 implants on each side of tibia. Three kinds of implants (machined surface implant, Sandblasted with Large grit and Acid etched implant, Resorbable Blast Media treated implant) were used. During the surgery implant insertion torque were measured with $Osseocare^{TM}$. After the 1, 4, 8, 12 weeks of healing time, animals were sacrificed and stability values (Implant Stability Quotient with $Osstell^{TM}$, removal torque with torque gauge) were measured. Results. The Bone quality of rabbit tibia was classified into 2 groups according to the insertion torque. Resonance frequency analysis (ISQ) and removal torque showed positive correlation until $4^{th}$ week (r=0.555, p=0.040). After $8^{th}$ week (r=0.011, p=0.970) the correlation became weak and it turned negative at $12^{th}$ week (r=-0.074, p=0.801). Insertion torque and ISQ showed changing correlation upon the healing time ($1^{st}$ week: r=0.301, p=0.033, $4^{th}$ week: r=-0.429, p=0.018, $8^{th}$ week: r=0.032, p=0.865, $12^{th}$ week: r=-0.398, p=0.029). Insertion torque and removal torque has positive correlation but it was not statistically significant ($1^{st}$ week: r=0.410, p=0.129, $4^{th}$ week: r=0.156, p=0.578, $8^{th}$ week: r=0.236, p=0.398, $12^{th}$ week: r=0.260, p=0.350). Conclusion. In this study, bone quality may affect the degree of osseointegration positively during healing time and correlation between ISQ and degree of osseointegration can be different according to the healing time and bone quality.

• 한국전문물리치료학회지
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• 제7권1호
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• pp.38-45
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• 2000

Tape measurement for evaluating edema is frequently used by clinicians. The primary purpose of this study is to determine the intertester and intratester reliability of tape measurement carried out by two physical therapists on lower extremities. The intertester and intratester reliability of six anatomical landmarks measurements were determined in six healthy subjects. The measurements were taken in five sessions by each tester. The intraclass correlation coefficients (2,1) were between .87 and .99 for intertester reliability. Intratester reliability was .93 and .99 for A tester and .82 and .99 for B tester. The average range of variation was .13 to .54 in six landmarks. The reliability of six volume measurements was very high. These results support the use tape measurement as a reliable tool for measuring limb girth.

• 한국초전도ㆍ저온공학회논문지
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• 제25권4호
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• pp.40-44
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• 2023

For high-temperature superconducting power applications that need large current capacity, a large current conductor manufactured using multiple superconducting tape is required. Conductors being studied for large currents capacity such as CORC, TSTC, and RACC have advantages and disadvantages, and in order to use these conductors in coil form and apply them to AC power devices, research on magnetization loss occurring in superconductors due to external magnetic fields is essential. To accurately measure magnetization loss in a conductor that is twisted by stacking straight conductors like TSTC, the correlation between the measuring system and the shape of the sample must be clearly known to accurately measure the loss. In this paper, we will confirm the difference in magnetization loss measurement values according to the correlation between the length of the pickup coil and the twist pitch of the sample in CORC and TSTC shapes, and review considerations for accurate magnetization loss measurement from the results.

• Journal of the Korean Data and Information Science Society
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• 제15권3호
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• pp.515-521
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• 2004

Categorical data are mostly found in oriental medical research. The nonlinear canonical correlation analysis does not assume an interval level of measurement. In this paper, we apply nonlinear canonical correlation analysis to quantification and explain how similar sets of variables are to one another for paralysis disease data.

• 성인간호학회지
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• 제12권4호
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• pp.741-757
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• 2000

This study was undertaken to develop an instrument to be used for measuring the concept of quality of life of Korean patients with cancer multidimensionary and correctly. It can contribute in holistic nursing care for Korean cancer patients and also provide and validate basic data to help oncology nurses measure the outcome of nursing intervention correctly. To develop this instrument, the researchers first estabilished a conceptual framework based on the results of qualitative data analysis and indepth interview method Development of the scale was conducted using a method in which 31 items were assessed by subjects' self report using linear analogue scales. The subjects were 79 D.M. patients, 103 patients with acute illness, and 91 cancer patients residing in Busan, Korea. Data were collected during the period from July, 24 to August 14, 2000. This instrument consisted of 31 items with a self report scale. This instrument covered 4 dimensions of cancer patients : 1) physical wellbeing 2) psychological wellbeing 3) social wellbeing and 4)spiritual wellbeing. Each item had a possible score of 10. The reliability of the scale was tested with Cronbach's alpha. Validity was evaluated by examining the relationships of this scale, Youn's Quality of Life Questionnare scores and the Simple Quality of Life scale. Two separate runs of multiple regression were used to predict scores on the Simple Quality of Life measurement. Further validation was obtained by examining the correlation between the instrument subscores and Youn's Quality of Life measurement subscore for convergence of this scale. Examination of the discriminant. power of the instrument was done using ANOVA test. The results are summarized as follows: 1. The reliability of the instrument for the quality of life was 0.8321(Cronbach's alpha.), physical wellbeing dimension 0.6343, psychological wellbeing dimension 0.6501, spiritual wellbeing dimension 0.5883. 2. This instrument had a high correlation with Youn's Quality of Life measurement(r= 0.636) in cancer patients, whereas it had a low correlation with Simple Quality of Life measurement(r=0.455) in cancer patients. In the D.M. patients, the instrument correlated with both the Youn's Quality of Life measurement and Simple Quality of life measurement(r=0.313, r= 0.407) and in the acute stage patients, the instrument had no correlation. 3. Multiple regression of individual items on the Simple Quality of Life scores accounted for 56.8% of the variance in the Simple Quality of Life measurement, whereas, Youn's Quality of Life measurement scores accounts for 31.7%. 4. The correlations collected from the three group had the same patterns of variations but especially the instrument developed in this study had higher disciminant power than that of Youn's Quality of Life Measurement.

• 한국정밀공학회지
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• 제31권10호
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• pp.889-895
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• 2014

Machine parts and structures of a change in the displacement and strain can be evaluated safety is one of the important factors. Typically the strain gauge has been employed to measure the displacement and strain. However, this contact-type measurement method has disadvantages that are not measured under condition of specific object shape, surface roughness and temperature. In particularly, 3 point bending and 4 point bending test not use strain gauge. So its test used cross head displacement and deflect meter. Digital Image Correlation measurement methods have many advantages. It is non contact-type measurement method to measure the object displacements and strain. In addition, it is possible to measure the Map of full field displacements and strain. In this paper, measured the 3 point bending deflection using the Digital Image Correlation methods. In order to secure the reliability, Digital Image Correlation method and universal test machine were compared.