• Smart Structures and Systems
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• v.4 no.4
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• pp.449-464
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• 2008

An array based, outward monitoring, ultrasonic guided wave based SHM technique using a single transmitter and multiple receivers (STMR), with a small footprint is discussed here. The previous implementation of such SHM arrays used a phase-reconstruction algorithm (that is similar to the beam-steering algorithm) for the imaging of reflectors. These algorithms were found to have a limitation during the imaging of defects/reflectors that are present in the "near-field" of the array. Here, the "near-field" is defined to be approximately 3-4 times the diameter of the compact array. This limitation is caused by approximations in the beam-steering reconstruction algorithm. In this paper, a migration-based reconstruction algorithm, with dispersion correction in the frequency domain, is discussed. Simulation and experimental studies are used to demonstrate that this algorithm improves the reconstruction in the "near-field" without decreasing the ability to reconstruct defects in the "far-field" in both isotropic and anisotropic plates.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.295-298
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• 2007

Recently, various problems have been occurred in Apartment reconstruction process. Such as, delaying schedule, additional cost increasing, etc. Those were caused by decision making which is lack of professionality in early phase of reconstruction process. Therefore, in this study proposed improvement plan by application of project management and construction management process in Apartment reconstruction project.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.251-256
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• 2001

After the late 70's, the apartment housing have been constructed numerously, but the apartment housing has been deteriorated and the maintenance cost has been increasingly upward as time goes by. Because of that, the reconstruction of the apartment housing is widespread in the late 90's. But as the owner, the congregation, is not an expert, there are many problems in the reconstruction projects. Thus, the necessity of the CM in the reconstruction project is getting higher, but the appropriate method for the application of the CM is not established yet. In this study, the CM work scope that is applicable in the reconstruction project is developed through the inquiry and interview to the experts. Especially, The work scope developed in this study is established to be adapted easily in the practical use for each project phase.

• Korean Journal of Construction Engineering and Management
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• v.23 no.2
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• pp.76-84
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• 2022

Recently, as the frequency of natural disasters has increased, causing enormous human and material damage, the importance of managing disasters is emphasized. In particular, as the concept of Build Back Better becomes meaningful, it has appeared that considering it during Post-disaster Reconstruction is a necessity. Therefore, in this study, the relative importance evaluation and correlation analysis were performed for each influencing factor through the derivation of the influencing factors that should be considered during the reconstruction approach stage of reconstruction after disasters, and a survey of overseas disaster-related experts. As a result of the analysis, 'Adaptability to the environment changes in the future was derived as the most significant influencing factor. It seems that the results of this study can be used as basic data when carrying out the reconstruction project.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.107-107
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2016.11a
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• pp.33-33
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• 2016

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.105-114
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• 1997

The phase retrieval problem is concerned with the reconstruction of a signal or its fourier transform phase form the fourier transform magnitude of the signal. This problem does not have a unique solution, in general. If, however, the desired signal is minimum-phase, then it can be decided uniquely. This paper shows that we can make a minimum-phase signal by adding a delta function having a large value at the origin of an arbitrary one-dimensional signal, and a two-dimensional signal can be uniquely specified from its fourier transform magnitude if it is added by a delta function having a large value at the origin, and finally we can solve a two-dimensional phase retrieval problem by decomposing it into several ine-dimensional phase retrieval problems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1186-1192
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• 2015

This paper proposes an economical method that the phase currents can be measured and reconstructed by means of the leg-shunt resistors in the 3-leg 2-phase vector-controlled inverter for 2-phase induction motor. In general, the phase currents of 2-phase induction motor have been measured using two Hall current sensors. However, because Hall current sensors are expensive, economically disadvantageous to apply in low power applications. The proposed method is verified by computer simulations and experiments to show the good performance of the vector control.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1275-1280
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• 2018

We demonstrated transmission direct phase-measuring deflectometry (DPMD) with a specular phase object having discontinuous surfaces by using two displays and a two-dimensional array detector for display and by recording the distorted fringe patterns. Three-dimensional (3D) information was obtained by calculating the height map directly from the phase information. We developed a mathematical model of the phase-height relationship in transmission DPMD. Unlike normal transmission deflectometry, this method supports height measurement directly from the phase. Compared with other 3D measurement techniques such as interferometry, this method has the advantages of being inexpensive and easy to implement.

• Journal of Digital Convergence
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• v.13 no.10
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• pp.287-293
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• 2015

This study proposed signal processing techniques and neural network with weighted fuzzy membership functions(NEWFM) to detect epileptic seizure from EEG signals. This study used wavelet transform(WT), sequential increment method, and phase space reconstruction(PSR) as signal processing techniques. In the first step of signal processing techniques, wavelet coefficients were extracted from EEG signals using the WT. In the second step, sequential increment method was used to extract peaks from the wavelet coefficients. In the third step, 3D diagram was produced from the extracted peaks using the PSR. The Euclidean distances and statistical methods were used to extract 16 features used as inputs for NEWFM. The proposed methodology shows that accuracy, specificity, and sensitivity are 97.5%, 100%, 95% with 16 features, respectively.