• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1217-1233
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• 2015

The paper studies characteristics of the minimum mean-square error symmetric scalar quantizers for the generalized gamma, Bucklew-Gallagher and Hui-Neuhoff probability density functions. Toward this goal, asymptotic formulas for the inner- and outermost thresholds, and distortion are derived herein for nonuniform quantizers for the Bucklew-Gallagher and Hui-Neuhoff densities, parallelling the previous studies for the generalized gamma density, and optimal uniform and nonuniform quantizers are designed numerically and their characteristics tabulated for integer rates up to 20 and 16 bits, respectively, except for the Hui-Neuhoff density. The assessed asymptotic formulas are found consistently more accurate as the rate increases, essentially making their asymptotic convergence to true values numerically acceptable at the studied bit range, except for the Hui-Neuhoff density, in which case they are still consistent and suggestive of convergence. Also investigated is the uniqueness problem of the differentiation method for finding optimal step sizes of uniform quantizers: it is observed that, for the commonly studied densities, the distortion has a unique local minimizer, hence showing that the differentiation method yields the optimal step size, but also observed that it leads to multiple solutions to numerous generalized gamma densities.

• Journal of IKEEE
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• v.21 no.3
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• pp.185-194
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• 2017

In this paper, a modular platform for wearable devices is proposed which can be easily assembled by exchanging functions according to various field and environment conditions. The proposed modular platform consists of a 32-bit RISC CPU, a 32-bit symmetric multi-core processor, and a 16-bit DSP. It also includes a plug & play features which can quickly respond to various environments. The sensing and communication modules are connected in the form of a chain. This work is implemented in a standard 130 nm CMOS technology and the proposed modular wearable platforms are verified with temperature and humidity sensors.

• Structural Engineering and Mechanics
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• v.48 no.3
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• pp.291-308
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• 2013

Structural health monitoring is crucial to maintain the structural performance safely. Moreover, the Kullback-Leibler divergence (KLD) is applied usually to asset the similarity between different probability density functions in the pattern recognition. In this study, the KLD is employed to detect the damage. However the asymmetry of the KLD is a shortcoming for the damage detection, to overcoming this shortcoming, two other divergences and one statistic distribution are proposed. Then the damage identification by the KLD and its three descriptions from the symmetric point of view is investigated. In order to improve the reliability and accuracy of the four divergences, the gapped smoothing method (GSM) is adopted. On the basis of the damage index approach, the new damage index (DI) for detect damage more accurately based on the four divergences is developed. In the last, the grey relational coefficient and hypothesis test (GRCHT) is utilized to obtain the more precise damage identification results. Finally, a clear remarkable improvement can be observed. To demonstrate the feasibility and accuracy of the proposed method, examples of an isotropic beam with different damage scenarios are employed so as to check the present approaches numerically. The final results show that the developed approach successfully located the damaged region in all cases effect and accurately.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.94-101
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• 2009

This paper presents scalable modeling of spiral inductors for RFIC design based on $0.13{\mu}m$ RF CMOS process. For scalable modeling, several inductor patterns are designed and fabricated with variations of width, number of turns and inner radius. Feeding structures are optimized for accurate de-embedding of pad effects. After measuring the S parameters of the fabricated patterns, double-$\pi$ equivalent circuit parameters are extracted for each device and their geometrical dependences are modeled as scalable functions. The inductor library provides two types of models including standard and symmetric inductors. Standard and symmetric inductors have the range of $0.12{\sim}10.7nH$ and $0.08{\sim}13.6nH$ respectively. The models are valid up to 30GHz or self-resonance frequency. Through this research, a scalable inductor library with an error rate below 10% is developed for $0.13{\mu}m$ RF CMOS process.

• Journal of Korean Society of Steel Construction
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• v.10 no.3 s.36
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• pp.509-523
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• 1998

A consistent finite element formulation and analytic solutions are presented for stability of thin-walled circular arch. The total potential energy is derived by applying the principle of linearized virtual work and including second order terms of finite semitangential rotations. As a result, the energy functional corresponding to the semitangential moment is newly derived. Analytic solutions for the out-of-plane buckling of symmetric thin-walled curved beam subjected to pure bending or uniform compression with simply supported boundary conditions are obtained. For finite element analysis, the cubic Hermitian polynomials are utilized as shape functions and $16{\times}16$ stiffness matrix for curved beam elements and $14{\times}14$ stiffness matrix for straight beam elements are evaluated, respectively. In order to illustrate the accuracy of this study, analytical and numerical results for lateral buckling problems of circular arch are presented and compared with available analytical solutions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.12
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• pp.35-41
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• 2011

In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite-Difference Time-Domain(FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Parameters of symmetric coupled MIS transmission line with various gaps between crossbars for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency-dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.169-175
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• 2008

The existing block encryption algorithms have been designed for the encryption key value to be unchanged and applied to the round functions of each block. and enciphered. Therefore, it has such a weak point that the plaintext or encryption key could be easily exposed by differential cryptanalysis or linear cryptanalysis, both are the most powerful methods for decoding block encryption of a round repeating structure. Dynamic cipher has the property that the key-size, the number of round, and the plaintext-size are scalable simultaneously. Dynamic network is the unique network satisfying these characteristics among the networks for symmetric block ciphers. We analyze the strength of Dynamic network for meet-in-the-middle attack, linear cryptanalysis, and differential cryptanalysis. Also, In this paper we propose a new network called Dynamic network for symmetric block ciphers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.3
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• pp.321-328
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• 2000

An improved formulation of thin-wailed curved beams with variable curvatures based on displacement field considering the second order terms of finite semitangential rotations is presented. From linearized virtual work principle by Vlasov's assumptions, the total potential energy is derived and all displacement parameters and the warping functions are defined at cendtroid axis. In developing the thin-walled curved beam element having eight degrees of freedom per a node, the cubic Hermitian polynomials are used as shape functions. In order to verify the accuracy and practical usefulness of this study, free vibrations and buckling analyses of parabolic and elliptic arche shapes with mono-symmetric sections are carried out and compared with the results analyzed by ABAQUS' shell element.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1653-1660
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• 2010

The user information stored in database have been leaked frequently. To protect information against malevolent manager on the inside or outside aggressor, it is one of the most efficient way to encrypt information and store to database. It is better to destruct information than not to use encrypted information stored in database. The encrypted database search system is developed variously, and used widely in many fields. In this paper, we implemented the scheme that can search encrypted document without exposing user's information to the untrusted server in mobile device. We compared and analyzed the result embodied with DES, AES, and ARIA based on symmetric key by searching time.

• ETRI Journal
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• v.27 no.5
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• pp.563-568
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• 2005

A motion-control chip contains major functions that are necessary to control the position of each motor, such as generating velocity command profiles, reading motor positions, producing control signals, driving several types of servo amplifiers, and interfacing host processors. Existing motion-control chips can only generate velocity profiles of fixed characteristics, typically linear and s-shape smooth symmetric curves. But velocity profiles of these two characteristics are not optimal for all tasks in industrial robots and automation systems. Velocity profiles of other characteristics are preferred for some tasks. This paper proposes a motion-control chip to generate velocity profiles of desired acceleration and deceleration characteristics. The proposed motion-control chip is implemented with a field-programmable gate array by using the Very High-Speed Integrated Circuit Hardware Description Language and Handel-C. Experiments using velocity profiles of four different characteristics will be performed.