• Structural Engineering and Mechanics
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• v.54 no.6
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• pp.1075-1095
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• 2015

The use of acoustic emission (AE) technique for detecting and monitoring damages and the progress on damages in different structures is widely used and has earned a reputation as one of the most reliable and well-established technique in non-destructive testing (NDT). Acoustic Emission is a very efficient and effective technology used for fracture behavior and fatigue detection in metals, fiberglass, wood, composites, ceramics, concrete and plastics. It can also be used for detecting faults and pressure leaks in vessels, tanks, pipes, as well as for monitoring the progression of corrosion in welding. This paper reviews major research developments over the past few years in application of acoustic emission in numerous engineering fields, including manufacturing, civil, aerospace and material engineering.

• Journal of Korean Society for Quality Management
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• v.28 no.3
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• pp.59-67
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• 2000

In analysis of resolution IV fractional factorial experiments, the main effects only are analyzed, even though we can get some useful information on the confounded 2-factor interactions. In this paper, we introduce an exploiting method of the confounded structure of interactions, especially for the near minimal resolution IV 3$^{t}$ fractional factorial designs developed by Anderson and Thomas (1979). Moreover, in this paper the application way of the proposed method is also discussed by analyzing some simulated data.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.906-907
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• 2011

본 논문은 3D 타원형 결함을 가진 알루미늄 판에 대하여 와전류 탐상 프로브 중 Impedance, T/R, T/T 프로브를 설계하여 결함에서의 특성을 파악하였다. 특성 파악을 위해 세 가지의 결함에 대하여 프로브 코일 임피던스의 실수, 허수 변화에 따른 와전류 센서의 특성을 비교하였다.

• Journal of the Korea Society of Computer and Information
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• v.20 no.9
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• pp.97-104
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• 2015

Recently, the need for real-time systems which are providing various types of information that occur in large quantities in IoT environment is increasing. In this paper, we propose a middleware system which can monitor in real time on a web environment. The proposed system is designed to be integrated by using communication functions provided by a network operating system and external sensors. The proposed system is compared with an existing system and analysed by the server performance testing tool.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.56-62
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• 2005

Because of the wide plane and the curved field of CRT rear projection high definition television, its MTF(modulation transfer function) can't be easily measured by the usual forward testing method. Then we propose a backward testing method for the MTF so that the object plane and the image analyzer of forward testing are located at positions opposite each other. We prefer to use the backward testing method because the forward testing method has poor accuracy caused by very small numerical aperture, low spatial resolutions, and long depth of focus. We found that the backward testing method was very easy to align and had high repeatability. We confirmed the confidence of results obtained by the backward testing method in comparison with designed results.

• Proceedings of the KIEE Conference
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• 1983.07a
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• pp.93-94
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• 1983

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.43-47
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• 1999

Recently, standardization organizations including ITU, ATM Forum, etc. have much interested in the interoperability issues between telecommunications products or services. Because interoperability issues are directly related to the improvement of qualities of telecommunications standards or services. Thus, this paper analyzes the trends of interoperability testing polices for quality improvement of telecommunications standards in major standardization organizations, for example ITU-T, ATM Forum, DAVIC, BC-lT 226(Europe), HATS Conference(Japan), including Korea. In addition this paper suggests the desirable national interoperability testing policies and directions for quality improvement of telecommunications standards or services.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.133-141
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• 2008

In this study, a new method for estimating the undrained shear strength $s_u$ of saturated clays using piezocone penetration test (CPTu) result is proposed. This is to develop more effective CPTu-based $s_u$ estimation method at lower cost with less uncertainty. For this purpose, a marine clay deposit is selected and tested through extensive experimental testing program including both in-situ and fundamental laboratory tests. The proposed method is based on a correlation between the undrained shear strength $s_u$ and the cone resistance $q_t$, without introduction of the total overburden stress into the $s_u-q_t$ correlation. As a result, no additional testing procedure for collecting undisturbed soils samples is required, which can reduce overall testing cost. To verify the proposed method, 4 test sites, which consist of a variety of soil conditions, are selected and used for comparison between measured and predicted undrained shear strength. From comparison, it is seen that predicted values of $s_u$ using the proposed method match well those from measured results.

• The Journal of the Korea Contents Association
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• v.11 no.8
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• pp.198-203
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• 2011

The BMD difference depending on QCT and QUS, whose usages are recently being increased for the test of BMD, was accessed for 106 subjects of a general health examination who were aged between 24~69 year-old and results were derived as follows. The measured value of BMD by QCT and QUS showed significant correlation in general (p>0.05). In terms of the difference generated between the measurement methods depending on sexes, the female subjects showed significantly low T-score in the test made through QUS (p<0.05). Depending on ages, there was T-score difference among the subjects aged more than 40 year-old within significant range (p<0.05). When it came to the effect depending on heights and on weights, no group showed significant difference and in a group with less than 22.9 of BMI value, the T-score was measured significantly low when testing it through QCT while other groups were not affected by any testing methods. Likewise, it may require a different measurement method when it comes to the measurement of bone mineral density depending on sex, age, height, and BMI among patients. Thus, it suggests obtaining accurate data by conducting various testing methods in case of a special occasion.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.49-55
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• 2010

In this paper, the stability of cracked cantilever T-beams subjected to subtangential follower force is investigated. Also, the effect of subtangential coefficient and crack on the natural frequency of T-beams is presented. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by the energy expressions using extended Hamilton's Principle. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. The values of critical follower force and the stability maps of cantilever T-beams are obtained according to the subtangential coefficient and crack severity. The results of this study will contribute to the safety testing and the stability estimation of cracked T-beams subjected to follower force.