• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.5
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• pp.12-25
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• 1994

A two dimensional constant geometry FFT algorithms and architectures with shuffled inputs and normally ordered outputs are presented. It is suitable for VLSI implementation because all buterfly stages have identical, regular structure. Also a methodology using shuffled FFT inputs and outputs to halve the number of butterfly stages connected by a global interconnection which requires much area is presented. These algorithms can be obtained by shuffling the row and column of a decomposed FFT matrix which corresponds to one butterfly stage. Using non-recursive and recursive pipeline, the degree of serialism and parallelism in FFT computation can be adjusted. To implement high performance high radix FFT easily and reduce the amount of interconnections between stages, the method to build a high radix PE with lower radix PE 's is discussed. Finally the performances of the present architectures are evaluated and compared.

• The Journal of the Acoustical Society of Korea
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• v.25 no.1E
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• pp.1-7
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• 2006

This study examines the reflection characteristic of a thin transition layer of the ocean bottom showing variability with respect to depth. In order to model the surficial sediment simply, we reduce the Biot model to the depth dependent wave equation for the pseudo fluid using the fluid approximation (weak frame approximation). From the reduced equation, the difference between the inherent frequency dependency of the reflection and the frequency dependency resulting from a thin transition layer is investigated. Using Tang's depth porosity profile model of the surficial sediment [D. Tang et al., IEEE J. Oceanic Eng., vol.27(3), 546-560(2002)], we numerically simulated the reflection loss and investigated the contribution from both frequency dependencies. In addition, the effects of different sediment type and varying depth structure of the sediment are discussed.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.8
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• pp.108-114
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• 1997

A simple and efficient method is presented for the dynamics of interconnected flexible beams having large rigid body rotations. A simple mass matrix is obtained by interpolating the displacements in the global inertia frame, and the elastic force is also simply computed by using linear finite element technique with the moving frame attached to the beam. For the beams connected by revolute joints, kinematic constraints and relative rotations between the beans are not required and the equations of motions are time integrated by a simple ODE technique. Numerical simulations are conducted to demonstrate the accuracy and efficiency of the present technique.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.528-530
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• 1998

This paper addresses analysis and design of a fuzzy model-based-controller for the control of uncertain SISO nonlinear systems. In the design procedure, we represent the nonlinear system by using a Takagi-Sugeno fuzzy model and construct a global fuzzy logic controller via parallel distributed compensation and sliding mode control. Unlike other parallel distributed controllers. this globally stable fuzzy controller is designed without finding a common positive definite matrix for a set of Lyapunov equations, and has good tracking performance. Furthermore, stability analysis is conducted not for the fuzzy model but for the real underlying nonlinear system. A simulation is included for the control of the Duffing forced-oscillation system, to show the effectiveness and feasibility of the proposed fuzzy control method.

• Structural Engineering and Mechanics
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• v.50 no.1
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• pp.73-88
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• 2014

Vibration characteristics of columns are influenced by their axial loads. Numerous methods have been developed to quantify axial load and deformation in individual columns based on their natural frequencies. However, these methods cannot be applied to columns in a structural framing system as the natural frequency is a global parameter of the entire framing system. This paper presents an innovative method to quantify axial deformations of columns in a structural framing system using its vibration characteristics, incorporating the influence of load tributary areas, boundary conditions and load migration among the columns.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2005-2007
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• 2001

A controller design problem for a discrete-time Takagi-Sugeno (TS) fuzzy systems is discussed. The switching-type controller is employed in this study. A switching-type fuzzy-model-based controller is constructed based on the spirit of "devide and conquer". The design condition of this controller is formulated in terms of linear matrix inequalities (LMIs), which guarantees the global stability of the controlled TS fuzzy systems. An example is included for ensuring the effecienct of the proposed control method.

• Journal of Engineering Education Research
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• v.13 no.5
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• pp.41-48
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• 2010

In this paper, we proposed "Future Design and Success Engineering in Global Society by Self-Innovation" (an abbreviated name: FDSE). We started to make a small experiment between Korea Maritime University and Yamagata University at the current year. After inspecting the results, especially, successful and unsuccessful points in our lecture, we have to develop the strong points and amend the week points, through making the analysis of success-failure, which is his favorite management method. We have to level up the contents of our work in the future. The students for this lecture would learn from experiences of "the common knowledge (common field of discussion)", held common languages, common thought, common system. They filled up the blanks of "The Matrix Frame" which is mentioned in the previous report, and they expressed their own way of life (work, study). As a matter of course, their personal private affairs must not be made public. It is quite happy that the cultural, economical exchanges between Korea and Japan are now in full flourish and people do a lot of traveling each other. However, if this project will start on the educational global standard, we have a world-wide significance. Moreover, we can promote goodwill between Korea and Japan, and also we can contribute to a better international understanding and the peace of the world by students in both Universities. We hope that candidates for this lecture will have a rounded personality and be a life worthy of human being for realizing Self-Actualization in "Motivation and Personality" by Abraham Maslow.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.251-256
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• 2019

In this paper we proposed system and algorithm to recognize hand gestures based on the millimeter wave that is in 65GHz bandwidth. The proposed system is composed of millimeter wave radar board, analog to data conversion and data capture board and notebook to perform gesture recognition algorithms. As feature vectors in proposed algorithm. we used global and local zernike moment descriptor which are robust to distort by rotation of scaling of 2D data. As Experimental result, performance of the proposed algorithm is evaluated and compared with those of algorithms using single global or local zernike descriptor as feature vectors. In analysis of confusion matrix of algorithms, the proposed algorithm shows the better performance in comparison of precision, accuracy and sensitivity, subsequently total performance index of our method is 95.6% comparing with another two mehods in 88.4% and 84%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.635-643
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• 1998

A spectral element method(SEM) is introduced for the vibration analysis of a rectangular plate subject to dynamic concentrated loads. First, the spectral plate element is derived from the relations between the forces and displacements along the two opposite edges of plate element. The global spectral matrix equation is then formulated by assembling two spectral plate elements so that the dynamic concentrated load is located at the connection nodal line between two plate elements. the concentrated load is then spatially Fourier transformed in the direction of the connection nodal line to transform the two-dimensional plate problem into a simplified equivalent one-dimensional beam-like problem. We may benefit from these procedures in that the spectral results from the present SEM is compared with the exact analytical solutions to prove the remarkable accuracy of the present SEM, while this is not true for conventional finite element solutions, especially at high frequency.

• Smart Structures and Systems
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• v.13 no.3
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• pp.389-406
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• 2014

Optimal sensor placement techniques play a significant role in enhancing the quality of modal data during the vibration based health monitoring of civil structures, where many degrees of freedom are available despite a limited number of sensors. The literature has shown a shift in the trends for solving such problems, from expansion or elimination approach to the employment of heuristic algorithms. Although these heuristic algorithms are capable of providing a global optimal solution, their greatest drawback is the requirement of high computational effort. Because a highly efficient optimisation method is crucial for better accuracy and wider use, this paper presents an improved simulated annealing (SA) algorithm to solve the sensor placement problem. The algorithm is developed based on the sensor locations' coordinate system to allow for the searching in additional dimensions and to increase SA's random search performance while minimising the computation efforts. The proposed method is tested on a numerical slab model that consists of two hundred sensor location candidates using three types of objective functions; the determinant of the Fisher information matrix (FIM), modal assurance criterion (MAC), and mean square error (MSE) of mode shapes. Detailed study on the effects of the sensor numbers and cooling factors on the performance of the algorithm are also investigated. The results indicate that the proposed method outperforms conventional SA and Genetic Algorithm (GA) in the search for optimal sensor placement.