• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.183-194
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• 2003

We will explain a new method for obtaining the nearly optimal domain for optimal shape design problems associated with the solution of a nonlinear wave equation. Taking into account the boundary and terminal conditions of the system, a new approach is applied to determine the optimal domain and its related optimal control function with respect to the integral performance criteria, by use of positive Radon measures. The approach, say shape-measure, consists of two steps; first for a fixed domain, the optimal control will be identified by the use of measures. This function and the optimal value of the objective function depend on the geometrical variables of the domain. In the second step, based on the results of the previous one and by applying some convenient optimization techniques, the optimal domain and its related optimal control function will be identified at the same time. The existence of the optimal solution is considered and a numerical example is also given.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.58-66
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• 2001

GPC has been reported as a useful self-tuning control algorithm for systems with unknown time-delay and parameters. GPC is easy to understand and implement, and thus has won popularity among many practicing engineers. Despite its success, GPC does not guarantee is nominal stability. So, in this paper, GPC is rederived in frequency domain instead of in the time domain to guarantee its nominal stability. Derivation of GPC in frequency domain involves spectral factorization and Diophantine equation. Frequency domain GPC control law is stable because the zeros of characteristic polynomial are strictly Schur. Recursive least square algorithm is used to identify unknown parameters. To see the effectiveness of the proposed controller, the controller is simulated for a numerical problem that changes in dead-time, in order and in parameters.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1605-1607
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• 2000

In this paper, the design of class AB BiCMOS log-domain filter for low-voltage and low-power was proposed. This filter is consist of a log-domain integrator using folded junctions with capacitor connected to emitter and it's class AB structure. A comparison between the proposed class AB BiCMOS log-domain filter and classical class A BiCMOS log-domain filter is drawn on the basis of SNR, THD and the frequency response. This comparison shows proposed filter are more than good SNR, THD and frequency characteristics than more class A log-domain filter for low voltage and low power.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.634-637
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• 2005

A subjective index of sound quality when it hit him is required since human listening is very sensitive and complex. Sound quality evaluation it leads consequently rightly in each situation and it composes a sound quality factor. But one of the levels in interest frequency range is substitute we cannot see the tendency of frequency substitute at whole that is executes a clear voice evaluation. Design of experiment is used and dividing 12 equally in frequency domain, the sound quality using sharpness and annoyance is performed by modifying each of frequency domains. Design of experiment method reduces much number experiment very effectively and each main effect of domain solution analysis, such as a case of sharpness and annoyance, the change of domain (increase and decrease of sound pressure level, or change nil) can grasp a type of effect should have influenced to a sound quality, and it will be able to select the objective frequency domain which hits to the sound quality. Through these obtained results the physical changes of level at arbitrary frequency domain sensitivity can be adapted.

• The Research Journal of the Costume Culture
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• v.26 no.1
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• pp.45-55
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• 2018

The purpose of this study was to investigate the changes in perception and attitude of fashion major college students before and after receiving their design copyright education. A questionnaire survey was distributed to 200 fashion major college students in Seoul. The results of this study were as follows: First, 46.0% of fashion major students had an experience of purchasing counterfeit fashion goods. Out of those, 81.5% students acknowledged that the product was counterfeit and still purchased it. Categories of counterfeit goods purchased were bags, clothes, and accessories, in order of popularity. The students reported purchasing counterfeit goods twice and three times, in order of popularity. The prices of the counterfeit products were 100,000 to under 200,000 won, and under 100,000 won, in order of popularity. Second, the cognitive domain, the practical domain, and the value domain all showed significant differences between before and after the copyright education. Among these, the differences in the practical domain were the most distinctive. Third, prior to receiving their copyright education, most of the students had no perception about the design copyright system and so most of the students gained helpful information from the education. For future design copyright education, the students want to learn about how to protect their own designs, how to apply copyright in a fashion company, how to avoid invading other people's designs, and categories of design copyright.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.4 s.175
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• pp.1016-1023
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• 2000

The present work is concerned with three-dimensional finite element analysis of the hollow section extrusion process using a porthole die. The effects of related design parameters are discussed through the finite element simulation for extrusion of a triply-connected rectangular tubular section. For economic computation, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain, is implemented. In order to obtain the uniform flow at the outlet, design parameters such as the hole size and the hole position are investigated and compared through the numerical analysis. Comparing the velocity distribution with that of the original design, it is concluded that the design modification enables more uniform flow characteristics. The analysis results are then successfully reflected on the industrial porthole die design.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.10
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• pp.1936-1941
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• 2009

This paper deals with a new methodology for topology optimization in which the topology of the design domain may change during the shape optimization process. To achieve this, the concept of the topological gradient is introduced to compute the sensitivity of an objective function when a small hole is drilled in the domain. Based on shape and topological sensitivity values, the shape and topology of the design domain may be simultaneously changed during design iterations if necessary. To verify the advantages and also to facilitate understanding of the method itself, two electrostatic design problems have been tested by using 2D finite element analysis: the first is the inverse problem of a simple dielectric model and the second is the rotor design of a MEMS actuator.

• Earthquakes and Structures
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• v.5 no.2
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• pp.129-142
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• 2013

Linear and nonlinear time history analyses have been becoming more common in seismic analysis and design of structures with advances in computer technology and earthquake engineering. One of the most important issues for such analyses is the selection of appropriate acceleration time histories and matching these histories to a code design acceleration spectrum. In literature, there are three sources of acceleration time histories: artificial records, synthetic records obtained from seismological models and accelerograms recorded in real earthquakes. Because of the increase of the number of strong ground motion database, using and scaling real earthquake records for seismic analysis has been becoming one of the most popular research issues in earthquake engineering. In general, two methods are used for scaling actual earthquake records: scaling in time domain and frequency domain. The objective of this study is twofold: the first is to discuss and summarize basic methodologies and criteria for selecting and scaling ground motion time histories. The second is to analyze scaling results of time domain method according to ASCE 7-05 and Eurocode 8 (1998-1:2004) criteria. Differences between time domain method and frequency domain method are mentioned briefly. The time domain scaling procedure is utilized to scale the available real records obtained from near fault motions and far fault motions to match the proposed elastic design acceleration spectrum given in the Eurocode 8. Why the time domain method is preferred in this study is stated. The best fitted ground motion time histories are selected and these histories are analyzed according to Eurocode 8 (1998-1:2004) and ASCE 7-05 criteria. Also, characteristics of both near fault ground motions and far fault ground motions are presented by the help of figures. Hence, we can compare the effects of near fault ground motions on structures with far fault ground motions' effects.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.6
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• pp.676-682
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• 1999

A study which develops a controller design methodology that has flexibility of eigenstructure assignment within the stability-robustness contraints of LQR is requried and has been performed. The previously developd control design methodology, namely, EALQR(Eigenstructure Assignment/LQR) has better performance than that of conventional LQR or eigenstructure assignment but has a constraint for the weitgting matrix in LQR, which could be indefinite for high-order system. In this paper, the effects of the indefinite Q in EALQR on the frequency domain properties are analyzed. The robustness criterion and quantitative frequency domain properties are also resented. Finally, the frequency domain properties of EALQR has been analyzed by applying to a flight control system design example.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.228-233
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• 2006

This paper introduces design method for air pump system using bond graph and genetic programming to maximize outflow subject to a constraint specifying maximum power consumption. The air pump system is a mixed domain system which includes electromagnetic, mechanical and pneumatic elements. Therefore an appropriate approach for a better system for synthesis is required. Bond graphs are domain independent, allow free composition, and are efficient for classification and analysis of models. Genetic programming is well recognized as a powerful tool for open-ended search. The combination of these two powerful methods, BG/GP, was tested for redesign of air pump system.