• Structural Monitoring and Maintenance
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• v.11 no.1
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• pp.41-55
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• 2024

This study aims to determine the characteristics of concrete as identified by Rebound Hammer and Ultrasonic Pulse Velocity (UPV) tests, focusing particularly on their efficacy in estimating compressive strength of concrete material. The study involved three concrete samples designed to achieve a target strength of 29 MPa, comprising normal concrete, instant concrete, and concrete with additives. These were cast into cube specimens measuring 150×150×150 mm. Compressive strength values were determined through both destructive and non-destructive testing on the cubic specimens. As a result, the non-destructive methods yielded varying outcomes for each correlation approach, influenced by the differing constituent materials in the tested concretes. However, normal concrete consistently showed the most reliable correlation, followed by concrete with additives, and lastly, instant concrete. The study found that combining Rebound Hammer and UPV tests enhances the prediction accuracy of compressive strength of concrete. This synergy was quantified through multivariate regression, considering UPV, rebound number, and actual compressive strength. The findings also suggest a more significant influence of the Rebound Hammer measurements on predicting compressive strength for BN and BA, whereas UPV and RN had a similar impact on predicting BI compressive strength.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.61-71
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• 2004

The performance evaluation and deflection of 3 spans concrete simplicity slab bridge analyzed by non-destructive and loading test. Compressive strength of slab and pier appeared in the range of each 353∼366 kgf/$cm^2$ and 152∼215 kgf/$cm^2$ in rebound number test. Also, it appeared that concrete quality of slab was good after performance improvement. The average compressive strength of slab by core picking appeared 229 kg/$cm^2$. In reinforcing bar arrangement test of span and member, it appeared that horizontal and vertical reinforcing bar was arranged to fixed interval. The value of calculation deflection that carried structural analysis with deflection analysis wave in static loading test appeared higher than that of experimental deflection and it appeared that hardness of this bridge was good. Maximum impact factor that estimated from deflection by running speed in dynamic loading test appeared by 0.216 in 10 km/hr running speed.

• Journal of Auto-vehicle Safety Association
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• v.13 no.2
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• pp.50-56
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• 2021

The purpose of this study is to investigate vulnerable parts of tower crane structures by analyzing extensive non-destructive test data. Approximately ten percent of domestically registered tower cranes were inspected by using magnetic particle inspection. The testing was carried out as advised in KS B 0213. The non-destructive results was analyzed with respect to jib types, age and crane size. As a result, the number of crack occurrences were the largest in mast parts, followed by main jib part. Moreover, it was found that turntables were important parts deserved to be noticed at the perspective of safe maintenance.

• Journal of Korean Society of Disaster and Security
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• v.15 no.4
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• pp.11-20
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• 2022

The general non-destructive inspection method for anchor bolts in Korea applies visual inspection and hammering inspection, but it is difficult to check corrosion or fatigue cracks of anchor bolts in the part included in the foundation or in the part where the nut and base plate are installed. In reality, objective investigation is difficult because inspection is affected by the surrounding environment and individual differences, so it is necessary to develop non-destructive inspection technology that can quantitatively estimate these defects. Inspection of the anchor bolts of domestic road facilities is carried out by visual inspection, and since the importance of anchor bolts such as bridge bearings and fall prevention facilities is high, the life span of bridges is extended through preventive maintenance by developing non-destructive testing technology along with existing inspection methods. Through the development of this technology, non-destructive testing of anchor bolts is performed and as a technology capable of preemptive/active maintenance of anchor bolts for road facilities, practical use is urgently needed. In this paper, the possibility of detecting defects in anchor bolts such as corrosion and cracks and reliability were experimentally verified by applying the ultrasonic test among non-destructive inspection techniques. When the technology development is completed, it is expected that it will be possible to realize preemptive/active maintenance of anchor bolts by securing source technology for improving inspection reliability.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.37-44
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• 2001

Ultrasonic testing has a characteristics such as excellent permeability, high-sensitivity to find defect and an almost exact measurement for position. size and direction of inner defect, which differ from other non-destructive testing. In the study, we developed program into optimal testing condition, to distinguish obstacle echo and defect position. This program shows generation and processing of ultrasonic pulse. We compared simulation with ultrasonic test in 45$^\circ$, 60$^\circ$and 70$^\circ$transducer. Test results were in accordance with simulation within 0.1~7.2%.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.13-16
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• 2005

This study is aimed to investigate the strength variation of fire-damaged reinforced concrete column by non-destructive test. It is studied to infer the recovery degree of residual strength of fire-damaged concrete. For measuring the surface hardness of RC columns. Schmidt hammer test is used. Testing is performed three-times: before fire test, directly after fire test and after 20 days.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.63-70
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• 2017

As the Non Destructive Test (NDT) for the welded structure, PT(Penetration Test). MT(Magnetic Test), RT (Radioisotope Test) and UT(Ultrasonic Test) methods are widely used in practice. These NDT methods have been developed toward high efficiency, low cost, real time, and high precise new NDT. For example, RT methods are developed to CT(Computed Tomography)and DR(Digital Radiography), and UT metheds are developed into Phased array, Guide wave, TOFD method. Moreover, the Infrared thermography and Laser ultrasonic technique are newly developed for applying in high temperature objects as the non-contact NDT methods. In this review paper the new high efficiency NDT methods for the welded structure are introduced and the trend of NDT rules applying in welded structure are described.

• Korean Journal of Agricultural Science
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• v.39 no.1
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• pp.111-116
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• 2012

Nondestructive evaluation of seed viability is one of the highly demanding technologies for seed production industry. Conventional seed sorting technologies, such as tetrazolium and standard germination test are destructive, time consuming, and labor intensive methods. Near infrared spectroscopy technique has shown good potential for nondestructive quality measurements for food and agricultural products. In this study, FT-NIR spectroscopy was used to classify normal and artificially aged lettuce seeds. The spectra with the range of 1100~2500 nm were scanned for lettuce seeds and analyzed using the principal component analysis(PCA) method. To classify viable seeds from nonviable seeds, a calibration modeling set was developed with a partial least square(PLS) method. The calibration model developed from PLS resulted in 98% classification accuracy with the Savitzky-Golay $1^{st}$ derivative preprocessing method. The prediction accuracy for the test data set was 93% with the MSC(Multiplicative Scatter Correction) preprocessing method. The results show that FT-NIR has good potential for discriminating non-viable lettuce seeds from viable ones.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.601-609
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• 2018

Steel bolts are used in the construction industry for a large variety of applications that range from fixing permanent installations to temporary fixtures. In the past much research has been focused on developing destructive testing techniques to estimate their pull-out load carrying capacity with very little attention to develop non-destructive techniques. In this regards the presented research work details the combined use of ultrasonic pulse velocity and Schmidt hammer tests to identify anchor bolts with faculty installation and to estimate their pull-out strength by relating it to the Schmidt hammer rebound value. From experimentation, it was observed that the load capacity of bolt depends on its embedment length, diameter, bond quality/concrete strength and alignment. Ultrasonic pulse velocity test is used to judge the quality of bond of embedded anchor bolt by relating the increase in ultrasonic pulse transit time to the presence of internal pours and cracks in the vicinity of steel bolt and the surrounding concrete. This information combined with the Schmidt hammer rebound number, R, can be used to accurately identify defective bolts which resulted in lower pull-out strength. 12 mm diameter bolts with embedment length of 70 mm and 50 mm were investigated using constant strength concrete. Pull-out load capacity versus the Schmidt hammer rebound number for each embedment length is presented.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.487-496
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• 2022

Most of the pile's vertical static load tests in construction sites are the proof load tests, which is difficult to accurately estimate the ultimate bearing capacity and analyze the reliability of piles. Therefore, a reliability analysis method based on the proof load-settlement (Q-s) data is proposed in this study. In this proposed method, a simple ultimate limit state function based on the hyperbolic model is established, where the random variables of reliability analysis include the model factor of the ultimate bearing capacity and the fitting parameters of the hyperbolic model. The model factor M = R_uR / R_uP is calculated based on the available destructive Q-s data, where the real value of the ultimate bearing capacity (R_uR) is obtained by the complete destructive Q-s data; the predicted value of the ultimate bearing capacity (R_uP) is obtained by the proof Q-s data, a part of the available destructive Q-s data, that before the predetermined load determined by the pile test report. The results demonstrate that the proposed method can easy and effectively perform the reliability analysis based on the proof Q-s data.