• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.33-46
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• 2007

HWAW (Harmonic Wavelet Analysis of Wave) method, which is non-destructive method using body and surface waves, has the advantages of obtaining 2D subsurface imaging because it uses a short receiver spacing to obtain the $V_s$ profile of whole depth. Even though the reliability of HWAW method has already been verified by using the numerical simulation in the various layered models, it is very difficult to evaluate the reliability of HWAW in the field because the exact $V_s$ values of the experimental site are unknown. In this study, a model testing site where the material properties and layer information could be controlled was constructed to verify the reliability of HWAW method. The detailed geometry of the testing site was strictly measured by surveying, and 140 vertical and horizontal geophones were established at the boundary of each layer to evaluate the dynamic material properties. Using the interval travel times between the upper and lower geophones, the body wave velocities of each layer were 2 dimensionally obtained as reference data, and comparative study using HWAW method was performed. By comparing 2D Vs profile obtained by HWAW method to the reference data, the reliability of HWAW method was verified.

• Magazine of the Korea Concrete Institute
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• v.6 no.6
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• pp.159-172
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• 1994

The relmund hammer test and ultrasonic pulse velocity test methods are commonly used to determine the in-situ compressive strength of concrete. One of the special feature of these methods is that they cannot give consistent and reliable results for variety of structures. In particular, very old existing structures have been generally received sreious environmental affectsand thus the strength prediction will be different from normal structures. The purpose of the present study is, therefore, to propose realistic equations to predict the in-situ strengths of actual old concrete structures. The rebound hammer and ultrasonic pulse velocity tests, carbonation depth measurments and core compressive strength measurements have been carried out for very old hydraulic and seacoast concrete structures spanning from one to about seventy years in age. From these test results, the strength-rebound number relations, the strength-pluse velocity relatinns and the strength-rebound number-pluse velocity relations have been obtained through multiple regression analysis. The present study indicates that the existing equations by nondestructive tests give quite different results from the present data. The proposed equations reasonably well predict the measured data for old concrete structures, especially for low strength concrete. The prediction equations proposed here can be efficiently used in determining the in-situ strength of old concrete structures.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.3
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• pp.266-276
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• 2020

The purpose of this study was to compare the remineralization effect of 38% silver diamine fluoride (SDF) and 5% sodium fluoride (NaF) varnish on artificially induced enamel caries. The present study standardized the physiochemical characteristics of the tooth structure using bovine teeth, realized the wash-off action of agents using a saliva, reproduced an environment similar to mouth through pH-cycling, and comparatively assessed the remineralization effect of 38% SDF and 5% NaF varnish in a non-destructive method using micro-CT. And the remineralized enamel surface structure was analyzed by scanning electron microscopy (SEM) and energy dispersive X-Ray spectroscopy (EDS). In both SDF and NaF varnish, mineral density (△Hounsfield unit value) and the volume of enamel restored to normal mineral density through remineralization gradually increased with time. And the SDF showed a much higher level of increase in mineral density at all depths and remineralized volume than NaF varnish. According to SEM analysis, the surface roughness decreased in the order of artificial saliva, NaF varnish and SDF. In addition, EDS analysis showed that silver ion was precipitated on the enamel surface in SDF group. In conclusion, SDF had a greater remineralization effect than NaF varnish on demineralized enamel.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.77-90
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• 2009

Near Infrared Reflectance Spectroscopy(NIRS) is a quick, accurate, and non-destructive method to measure multiple nutrient components in plant leaves. This study was to acquire a liner regression equation by evaluating the nutrient contents of 'CY2' creeping bentgrass rapidly and accurately using NIRS. In particular, nitrogen fertility is a primary element to keep maintaining good quality of turfgrass. Nitrogen, moisture, carbohydrate, and starch were assessed and analyzed from 'CY2' creeping bentgrass clippings. A linear regression equation was obtained from accessing NIRS values from NIR spectrophotometer(NIR system, Model XDS, XM-1100 series, FOSS, Sweden) programmed with WinISI III project manager v1.50e and ISIscan(R) (Infrasoft International) and calibrated with laboratory values via chemical analysis from an authorized institute. The equation was formulated as MPLS(modified partial least squares) analyzing laboratory values and mathematically pre-treated spectra. The accuracy of the acquired equation was confirmed with SEP(standard error of prediction), which indicated as correlation coefficient($r^2$) and prediction error of sample unacquainted, followed by the verification of model equation of real values and these monitoring results. As results of monitoring, $r^2$ of nitrogen, moisture, and carbohydrate in 'CY2' creeping bentgrass was 0.840, 0.904, and 0.944, respectively. SEP was 0.066, 1.868, and 0.601, respectively. After outlier treatment, $r^2$ was 0.892, 0.925, and 0.971, while SEP was 0.052, 1.577, and 0.394, respectively, which totally showed a high correlation. However, $r^2$ of starch was 0.464, which appeared a low correlation. Thereof, the verified equation appearing higher $r^2$ of nitrogen, moisture, and carbohydrate showed its higher accuracy of prediction model, which finally could be put into practical use for turf management system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.63-70
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• 2017

In this paper, a magnetic flux leakage(MFL) based steel bar damage detection was first researched to quantify the signals from damages on the wire rope. Though many researches inspecting damages using a MFL method was proceeded until the present, the researches are at the level that diagnose whether damages are or not. This has limitation to take measures in accordance with the damage level. Thus, a MFL inspection system was modeled using a finite element analysis(FEM) program dealing with electromagnetism problems, and a steel bar specimen was adopted as a ferromagnetic object. Then, an experimental study was also carried out to verify the simulation results with a steel bar which has same damage conditions as the simulation. The MFL signals was nearly not affected by the increase of the inspection velocity, and the magnitudes of the signals are not identical according to the change of the defect width even the defects have same depth. On the basis of the analysis, the signal properties from the damages were extracted to classify the type of damages, and it could be confirmed that classification of damages using extracted signal properties is feasible.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.4
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• pp.410-417
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• 2012

Currently domestic thermal and nuclear power plants are comprised of many type's condenser and steam generator tubes to produce the electricity of good quality. There are some methods to inspect these tubes in the event that several defects were discovered in these facilities. Among many non-destructive methods, we used guided wave to inspect the soundness of tubes, because this method is very fast to detect the defect and very simple to install the equipment and also, can inspect up to the long range at a fixed point. Also, this method has a drawback that does not detect a very small size defect. So, we made an effort to overcome this drawback through the experimentation and signal analysis according to the size and shape of the defect through the manufacture of various artificial cracks capable to generate within the small size tube in the study and we anticipate that these detect limits can be overcome along with the development of the signal processing and manufacturing technology of the sensor for the inspection.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.1
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• pp.31-37
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• 2014

The aim of this study was the non-destructive evaluation of bloody eggs using VIS/NIR spectroscopy. The bloody egg samples used to develop the sorting mode were produced by injecting chicken blood into the edges of egg yolks. Blood amounts of 0.1, 0.7, 0.04, and 0.01 mL were used for the bloody egg samples. The wavelength range for the VIS/NIR spectroscopy was 471 to 1154 nm, and the spectral resolution was 1.5nm. For the measurement system, the position of the light source was set to $30^{\circ}$, and the distance between the light source and samples was set to 100 mm. The minimum exposure time of the light source was set to 30 ms to ensure the fast sorting of bloody eggs and prevent heating damage of the egg samples. Partial least squares-discriminant analysis (PLS-DA) was used for the spectral data obtained from VIS/NIR spectroscopy. The classification accuracies of the sorting models developed with blood samples of 0.1, 0.07, 0.04, and 0.01 mL were 97.9%, 98.9%, 94.8%, and 86.45%, respectively. In this study, a novel nondestructive sorting technique was developed to detect bloody brown eggs using spectral data obtained from VIS/NIR spectroscopy.

• Conservation Science in Museum
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• v.19
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• pp.19-40
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• 2018

Most stone monuments in Korea are made from the granitoids found extensively throughout the nation. To identify the provenance of the stone materials, this study carried out comprehensive analyses of the occurrence, physical properties, mineralogy, and chemical composition of Stupa for National Preceptor Wongong at Geodonsa Temple and Five-story Pagoda at Cheonsusa Temple, both located in the Gangwon region. Their features were compared with those of granite from Wonju City near the sites of the two monuments. Stupa for National Preceptor Wongong is composed purely of two-mica granite, whereas Five-story Pagoda was made from both two-mica and biotite granites. The occurrence and magnetic susceptibility of the two granite monuments generally coincide with those of granite from Wonju. When selecting materials for the restoration of stone monuments, it is deemed necessary to carry out a field survey on granite in areas adjacent to the locations of the stone monuments subject to restoration.

• Food Science and Preservation
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• v.24 no.1
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• pp.145-152
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• 2017

In this study, near infrared (NIR) spectroscopy known as a non-destructive analysis technique was applied to investigate peptide cleavage and consequent release of amino acids in soybean lumps as affected by its moisture content and incubation time during fermentation at 25 for 3 weeks. The NIR spectra of the soybean lump semi-dried and soaked in saline water showed that absorption intensity around 1,400 nm originating from hydrogen bonds of water decreased and absorption band shifted to 1,430 nm as moisture content decreased during incubation at 25 for 3 weeks. In addition, absorption around 2,050 nm which was assigned to amino groups increased as incubation time increased. NIR spectra data from 1,000 to 2,250 nm showed higher accuracy in the discriminant analysis between outside and inside parts of fermented soybean lumps than visible spectra result. NIR spectroscopy for the amino acid and moisture contents in traditional fermented soybean lumps showed relatively good accuracy with the multiple correlation coefficient ($R^2$) of 0.91 and 0.81, respectively, and root mean square error of cross validation (RMSECv) of 0.23 and 0.83%, respectively, in partial least square regression (PLSR). These results indicate that NIR spectral observations could be applicable to control the fermentation process for preparation of soybean products.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.1
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• pp.61-66
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• 2022

Sesamin and sesamolin are major lignan components with a wide range of potential biological activities of sesame seeds. Near infrared reflectance spectroscopy (NIRS) is a rapid and non-destructive analysis method widely used for the quantitative determination of major components in many agricultural products. This study was conducted to develop a screening method to determine the lignan contents for sesame breeding. Sesamin and sesamolin contents of 482 sesame samples ranged from 0.03-14.40 mg/g and 0.10-3.79 mg/g with an average of 4.93 mg/g and 1.74 mg/g, respectively. Each sample was scanned using NIRS and calculated for the calibration and validation equations. The optimal performance calibration model was obtained from the original spectra using partial least squares (PLS). The coefficient of determination in calibration (R²) and standard error of calibration (SEC) were 0.963 and 0.861 for sesamin and 0.875 and 0.292 for sesamolin, respectively. Cross-validation results of the NIRS equation showed an R² of 0.889 in the prediction for sesamin and 0.781 for sesamolin and a standard error of cross-validation (SECV) of 1.163 for sesamin and 0.417 for sesamolin. The results showed that the NIRS equation for sesamin and sesamolin could be effective in selecting high lignan sesame lines in early generations of sesame breeding.