• Journal of the Korean Society for Nondestructive Testing
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• v.3 no.1
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• pp.19-25
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• 1983

Some studies have been made on the effects of the attenuation on the result of ultrasonic examination of austenitic stainless steel weldment and also on the cause of false indications. The differences in the amplitudes and the metal paths of the ultrasonic examinations have been measured experimentally, for two kinds of waves, one passed through only the parent material and the other one through the weldment. The effect of probe angles and frequency on the examination data have been investigated using the shear wave. It has been found that the false indications were caused by back reflection from the weld metal surface due to the characteristics of ultrasonic wave propagation. It has been confirmed that the probe of $2.25\;MHz\;and\;60^{\circ}$ is the best choice in the ultrasonic examination and that the correction of amplitude for attenuations is necessary.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.475-482
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• 2005

The iterative calculation by least square method was used to determine the source location of acoustic emission in rock, as so called "traditional method". The results were compared with source coordinates infered from the application of neural network system for new input data, as so called "new method". Input data of the neural network were based on the time differences of longitudinal waves arrived from acoustic emission events at each transducer, the variation of longitudinal velocities at each stress level, and the coordinates of transducer as in the traditional method. The momentum back propagation neural network system adopted to determine source location, which consists of three layers, and has twenty-seven input processing elements. Applicability of the new method were identified, since the results of source location by the application of two methods were similarly concordant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.481-484
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• 2004

A form of measured temperature distribution to estimate condition of a electrical apparatus is a absolute reference for condition of the apparatus, time rate of transition, and difference between reference and currently temperature. Because passive thermography which has not injection of external thermal stimulation shows difference of temperature being on surface of a structure and temperature difference between the structure and back ground, the result could apply only to estimation or monitor for condition of terminal relaxation and overload related with temperature rising. However, a thermal flow in active thermography is differently generated by structure and condition of surface and subsurface. This paper presents the nondestructive testing using the properties and includes the results by heat injection and cooling to the apparatus. The buried discontinuity of subsurface could be detected by these techniques.

• Structural Engineering and Mechanics
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• v.22 no.1
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• pp.53-70
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• 2006

The paper summarizes the dynamic-based assessment of a reinforced concrete arch bridge, dating back to the 50's. The outlined approach is based on ambient vibration testing, output-only modal identification and updating of the uncertain structural parameters of a finite element model. The Peak Picking and the Enhanced Frequency Domain Decomposition techniques were used to extract the modal parameters from ambient vibration data and a very good agreement in both identified frequencies and mode shapes has been found between the two techniques. In the theoretical study, vibration modes were determined using a 3D Finite Element model of the bridge and the information obtained from the field tests combined with a classic system identification technique provided a linear elastic updated model, accurately fitting the modal parameters of the bridge in its present condition. Hence, the use of output-only modal identification techniques and updating procedures provided a model that could be used to evaluate the overall safety of the tested bridge under the service loads.

• Physical Therapy Korea
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• v.22 no.3
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• pp.1-11
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• 2015

The purpose of this study was to investigate the effect of lumbar stabilization training and additional thoracic mobilization on pain, proprioception and static balance in patients with chronic low back pain. The subjects of this study were 48 chronic low back pain patients who were randomly allocated to an experimental group 1 ($n_1=16$, lumbar stabilization and thoracic mobilization, thoracic hypomobility), experimental group 2 ($n_2=16$, lumbar stabilization and thoracic mobilization, thoracic normal mobility), and a control group ($n_3=16$, lumbar stabilization, thoracic hypomobility) after a thoracic mobility test. Both experimental groups underwent lumbar stabilization training and additional thoracic mobilization. The control group underwent only lumbar stabilization training. The intervention was performed 3 times per week, 30 minutes each time, for a total of 6 weeks. Thoraco-lumbar joint reposition error was measured using an electrogoniometer and static balance ability was measured using the Tetrax posture analysis system. Subjects' pain level was measured using a 100 mm visual analogue scale. Statistical analyses were performed using a one-way analysis of variance and a paired t-test. Post-hoc testing was carried out with a Bonferroni test. The pain level was significantly lower in both experimental groups compared to the control group. Both experimental groups showed significant reductions in joint reposition error angle (flexion, extension, and side bending) compared to the control group. The static balance level was significantly lower in both experimental groups than in the control group. In summary, lumbar stabilization exercises and additional thoracic mobilization significantly improved the pain level, proprioception, and static balance in patients with chronic low back pain.

• The Journal of Korean Physical Therapy
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• v.26 no.5
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• pp.344-350
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• 2014

Purpose: The purpose of this study was to translate and culturally adapt the International Classification of Functioning, Disability and Health (ICF) into the Korean language. Methods: The process of translation and adaptation of the ICF used here followed the translation guidelines of WHO. Implementation of this procedure comprised of four steps; forward translation, expert panel back-translation, pre-testing and cognitive interviewing, and final adaptation. The translators included health professionals with knowledge of ICF and non-health professionals blinded to the ICF. Clinical academics with significant experience in the use of disability survey, medical doctors, special educators, related policy makers, clinicians, architecture professionals, and international experts in ICF were invited to integrate all versions of the ICF for testing; 151 clinicians volunteered from 19 medical institutes across the country. Four different core-sets and a questionnaire were used for testing its practical usability and adaptation. Results: All translations were reviewed and a consensus was reached on any discrepancy from the earlier versions. Over 90% of the newly translated version of K-ICF was found to be different from the 2004 K-ICF version in the ICF language. Understanding of K-ICF language was responded difficult and very difficult by 50% of participants, whereas its practical use was responded 'useful' by more than 50% of subjects. Conclusion: It can be suggested that the new version of K-ICF should be widely used for final adaptation in the field of areas. Future studies will be required for implementation of K-ICF.

• Journal of KIISE
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• v.44 no.6
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• pp.595-600
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• 2017

Android applications are composed of one or more components. The components within an application or several applications may interact with each other primarily through intents. Such interactions may cause security and reliability issues such as broadcast theft, activity hijacking, and intent spoofing. These problems need to be resolved through testing techniques using various interaction test scenarios before an application gets launched. However, with the existing test scenario generation approach, some infeasible test scenarios may be generated since they do not consider the re-execution order based on activity setting when pressing the back button. This paper proposes a test case generation technique which removes infeasible interaction paths by utilizing the activity stack information.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.497-502
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• 2010

Many forces are pressuring utilities to reduce operating and maintenance costs without cutting back on reliability or availability. Many utility managers are re-evaluating maintenance strategies to meet these demands. To utilities how to reduce maintenance costs and extent the effective operating life of equipment, predictive maintenance technique can be adapted. Predictive maintenance has three types program which arc in-house program, engineering company program and mixed program. We can approach successful predictive maintenance program with "smart trust" concept.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.187-192
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• 2009

Telecommand & telemetry control equipment is needed for the testing of the transponders during the development of satellite. This equipment must have a loopback function to perform the self testing without satellite. The fabrication of the designed system is easier and cheaper than the conventional testing system using direct modulation method. The measured results of fabricated equipment are satisfied with required specifications. A overall path loss of uplink and downlink is 47.8 dB and 42.6 dB, respectively. Also, IMD3 of uplink has measured 60.68 dBc at an output of -50 dBm.

• Current Optics and Photonics
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• v.8 no.2
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• pp.127-137
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• 2024

The distribution of tags is an important factor that affects the performance of radio-frequency identification (RFID). To study RFID performance, it is necessary to obtain RFID tags' coordinates. However, the positioning method of RFID technology has large errors, and is easily affected by the environment. Therefore, a new method using optical measurement is proposed to achieve RFID performance analysis. First, due to the possibility of blurring during image acquisition, the paper derives a new image prior to removing blurring. A nonlocal means-based method for image deconvolution is proposed. Experimental results show that the PSNR and SSIM indicators of our algorithm are better than those of a learning deep convolutional neural network and fast total variation. Second, an RFID dynamic testing system based on photoelectric sensing technology is designed. The reading distance of RFID and the three-dimensional coordinates of the tags are obtained. Finally, deep learning is used to model the RFID reading distance and tag distribution. The error is 3.02%, which is better than other algorithms such as a particle-swarm optimization back-propagation neural network, an extreme learning machine, and a deep neural network. The paper proposes the use of optical methods to measure and collect RFID data, and to analyze and predict RFID performance. This provides a new method for testing RFID performance.