• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.310-323
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• 1990

A three-noded, with three degree-of-freedom at each node, in-plane curved beam element is formulated and employed in eigen-analysis of constant curvature beam. The conventional quadratic shape functions used in a three noded C .deg. type curved beam element produce such an undesirable large stiffness that a significant error is introduced in displacements and stresses. These phenomena are called 'Stiffness Locking Phenomena', which result from spurious strain energy due to inappropriate assumptions on independent isoparametric quadratic interpolation functions. Stiffness locking phenomena can be alleviated by using modified interpolation functions which get rid of spurious constraints of conventional interpolation functions. Eigenvalues and their modes as well as displacements and stresses may be locked because they are related to stiffness. Using modified curved beam element in eigenvalue problem of cantilever and arch, the property and performance of modified curved beam element are examined by numerical experimentations. In these eigen-analyses, mass matrices are calculated by using both modified and unmodified curved beam element, are compared with theoretical solutions. These comparisons show that the performance of the modified curved beam element is better than that of the unmodified curved beam element.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.4
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• pp.582-591
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• 2001

It is known that the reduced integration, modified shape function, anisoparametric and non-conforming element can reduce the error induced by stiffness locking phenomenon in the finite element analysis. In this study, we propose new anisoparametric curved beam element. The new element based on reduced minimization theory is composed of different shape functions in each displacement field. By the substitution of this modified shape function, the unmatched coefficient that cause stiffness locking in the constraint energy is eliminated. To confirm the availability of this new model, we performed numerical tests for a simple model. As a result of numerical test, the undulate stress patterns are disappeared in static analysis, and displacements and stresses are close to exact solution. Not only in the static analysis but also in the eigen analysis of free vibrated curved beam model, this element shows successful convergent results.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.6
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• pp.439-445
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• 2005

The stud bolt is one of crucial parts for safe operation of reactor vessels in nuclear power plants, Crack initiation and propagation were reported in stud bolts that arc used for closure of reactor vessel and head, Stud bolts are inspected by ultrasonic technique during overhaul periodically for the prevention of stud bolt failure which could induce radioactive leakage from nuclear reactor, In conventional ultrasonic testing for inspection of stud bolts, cracks are detected by using shadow effect It takes too much time to inspect stud bolts by using conventional ultrasonic technique. In addition, there were numerous spurious signals reflected from every oblique surfaces of thread, In this study, the signal processing technique for enhancing conventional ultrasonic technique was introduced for inspecting stud bolts. The signal processing technique provides removing spurious signal reflected from every oblique surfaces of thread and enhances detectability of defects. Detectability for small crack was enhanced by using this signal processing in ultrasonic inspection of stud bolts in Nuclear Power Plants.

• The Korean Journal of Applied Statistics
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• v.29 no.6
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• pp.999-1005
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• 2016

The advent of big data brings the opportunity to answer many open scientic questions but also presents some interesting challenges. Main features of contemporary datasets are the high dimensionality and massive sample size. In this paper, we give an overview of major challenges caused by these two features: (1) noise accumulation and spurious correlations in high dimensional data; (ii) computational scalability for massive data. We also provide applications of big data in various fields including forecast of disasters, digital humanities and sabermetrics.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.76-80
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• 2010

It is floating to security of information and the early assignment that it is important it processes and to transmit in inundations of information that I changed suddenly. I used the encryption/decryption process that applied simple substitution and mathematical calculation algorithm at theory and encryption transmission steps protective early information. Hardware and financial loss are using spurious random number to be satisfied with the random number anger that isn't real random number to size so much perfect information protection using One-time pad for applying this. I was transformed into serial test under a test to prove spurious random number anger, and it is into random number anger stronger, and the transformation serial test that proposes is proving it in algorithm speed and efficiency planes.

• Journal of electromagnetic engineering and science
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• v.11 no.2
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• pp.105-112
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• 2011

In phase-locked frequency synthesizers, a fast-lock technique is frequently employed to overcome the trade-off between a lock-time and a spurious response. The function of fast-lock in a conventional PLL (Phased Lock Loop) IC (Integrated Circuit) is limited by a factor of 16, which is usually implemented by a scaling of charge pumper, and consequently a lock time improvement of a factor of 4 is possible using the conventional PLL IC. In this paper, we propose a novel external active fast-lock loop filter. The proposed loop filter provides, conceptually, an unlimited scaling of charge pumper current, and can overcome conventional trade-off between lock-time and spur suppression. To demonstrate the validity of our proposed loop-filter, we fabricated an X-band frequency synthesizer using the proposed loop filter. The loop filter in the synthesizer is designed to have a loop bandwidth of 100 kHz in the fast-lock mode and a loop bandwidth of 5 kHz in the normal mode, which corresponds to a charge pumper current change ratio of 400. The X-band synthesizer shows successful performance of a lock-time of below 10 ${\mu}sec$ and reference spur suppression below -64 dBc.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.2
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• pp.301-314
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• 2015

Aiming at accurately distinguishing modeless component and natural vibration mode terms from data series of nonlinear and non-stationary processes, such as Vortex-Induced Vibration (VIV), a new empirical mode decomposition method has been developed in this paper. The key innovation related to this technique concerns the method to decompose modeless component from non-stationary process, characterized by a predetermined 'maximum intrinsic time window' and cubic spline. The introduction of conceptual modeless component eliminates the requirement of using spurious harmonics to represent nonlinear and non-stationary signals and then makes subsequent modal identification more accurate and meaningful. It neither slacks the vibration power of natural modes nor aggrandizes spurious energy of modeless component. The scale of the maximum intrinsic time window has been well designed, avoiding energy aliasing in data processing. Finally, it has been applied to analyze data series of vortex-induced vibration processes. Taking advantage of this newly introduced empirical decomposition method and mode identification technique, the vibration analysis about vortex-induced vibration becomes more meaningful.

• Nuclear Engineering and Technology
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• v.17 no.4
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• pp.302-316
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• 1985

Small break LOCA caused by a stuck-open PORV is one of the important contributors to nuclear power plant risk. This paper deals with the design of a pressurizer surveillance system using microcomputer to prevent the malfunction of system and has assessed the effect of this improvement through Probabilistic Risk Assessment (PRA) method. Micro-computer diagnoses the malfunction of system by a process checking method and performs automatically backup action related to each malfunction. Owing to this improvement, we can correctly diagnose “Spurious Opening”, “Fail to Reclose” and “Small break LOCA” which are difficult for operator to diagnose quickly and correctly and reduce the probability of a human error by an automatic backup action.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2819-2827
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• 1997

A dielectric waveguide structure using rectangular dielectic strip is analyzed directly in terms of the wave equation for quasi TE and quasi TE and quasiTM modes. This problem can be solved, with no approximation in the wave equation for the electric field $\vec{E}$ and magnetic field $\vec{H}$ inside and outside the dielectric rectangular waveguide matching the boundary conditions between interfaces. This leads to an eigenvalue problem where spurious modes do not appear. Dispersion characeristic examples are presented for square and rectangular waveguides. The formulation is general and can be used for compuarison with ogher methods such as FDM or FEM in various structures.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.8-12
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• 2016

A planar, light-weight, and low-cost notch filter structure is required for the KSTAR ECEI (Electron Cyclotron Emission Imaging) system to protect the mixer arrays from spurious plasma heating power. Without protection, this heating power can significantly degrade or damage the performance of the mixer array. To protect mixer arrays, a frequency selective surface (FSS) structure is the suitable choice as a notch filter to reject the spurious heating power. The FSS notch filter should be located between the lenses of the ECEI system. This paper presents a 170 GHz FSS notch filter for the KSTAR ECEI sensor application. The design of such an FSS notch filter is based on the single-sided square loop geometry, because that makes it relatively insensitive to the incident angle of incoming wave. The FSS notch filter exhibits high notch rejection with low pass-band insertion loss over a wide range of incident angles. This paper also reviews the simulated and measured results. The proposed FSS notch filter might be implemented in other millimeter-wave plasma devices.