• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.270-281
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• 2017

In this paper, a vibratory disturbance to the rotor system generated by gyroscopic precession through helicopter rotor is examined. Also, active vibration reduction method is designed and simulated by designing feedback controller. For this purpose, structural analysis is carried out using EDISON's geometric exact beam program which can analyze the rotor with the cantilever condition. And the aeroelastic analysis is performed by coupling it with the simple aerodynamic model. In order to obtain the real-time structural response, the EDISON program analysis results were modeled by nonlinear equations and the Newton-Raphson method was used for the trim analysis.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.2
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• pp.76-82
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• 2002

The objective of this paper is to design a robust controller for a flexible robot arm manipulator using LMI(Linear Matrix Inequality) theory, and confirm its effectiveness through experimentation. We first describe a modeling Process of the flexible arm in order to get a mathematical model, and then discuss how to approximately obtain the uncertainty of the model for robust control. As to the control system design, we adopt the LMI-based H$_{\infty}$ synthesis algorithm which has the merits of eliminating the regularity restrictions attached to the Riccati-based methods. As a result of this, we can cope with the parameter variation (that is, modeling uncertainty) due to the tip-load variation. Finally we confirm the effectiveness of the controller through experiment and simulation.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.87-94
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• 2006

Grid computing has been developed for resolving large-scaled computing problems through geographically distributed heterogeneous resources. In order to guarantee effective and reliable job processing, grid computing needs resource scheduling model. So, we propose a resource performance measurement scheduling model which allocates job to resources with resource performance measurement. We assess resources using resource performance measurement formula, and implement the resource performance measurement scheduling model in DEVS simulation modeling.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.500-506
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• 2006

An optical fiber displacement sensor has the advantages of relatively simplicity, cheap, small probe size and immunity against environmental perturbation. The working principle of the sensor is based on the intensity modulation that is detection light intensity reflecting from the surface being measured. This paper presents the mathematical model of displacement measurement mechanism of this sensor type. The theoretical and experimental data are compared to verify the model in describing the realistic approach to sensor design. Finally, the analysis results show that displacement response characteristics such as sensitivity, measuring range are easily modified by principal design parameters such as magnitude of optical Power, diameter of optical fiber core and distance between transmitting fiber and receiving fiber.

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.319-326
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• 1994

Automatic control has been for the most part applied to linear systems where ti can be approximately formalized. In case that it is not definitely established the mathematical modelling to control objects, it requires manual control strategies which put under the human rule. In this paper, it constructs an FLC (Fuzzy Logic Controller) in order to turn a hand control into an automatic control in the domain of swimming pool that has been almost absolutely dependant on a skilled worker's experience. Genetic algorithms upgrade the knowledge which is acquired from human expert, using by FLC, so as to maintain knowledge in the very optimal way. It also designs an algorithm that modifies the rule base and the membership function at the same time, and ultimately will show that it can get better result than human controllers.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.23-30
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• 2007

The effectiveness of a pogo suppression device (PSD) on the response of piping system simulating the propellant supply lines of the rocket engines was investigated experimentally by other researchers. In this study, the simplified analytical model was made, and the key parameters which are difficult to derive theoretically were identified in combination with the previous experimental work. In other words, the flow transient equations for a PSD system and the key parameters used to decide the instability of the system from the linearized transfer function including inertance, compliance, and resistance were derived. From the analysis, the values of key parameters could be determined from the experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1677-1685
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• 2004

Recently, FD (Frame Dropping)-CD (Coefficient Dropping) transcoding is considered due to the low computational complexity and simple implementation. The conventional FD-CD transcoding schemes have not considered the CD errors that tend to be propagated and accumulated. In this paper, we derive the error characteristics incurred by the CD errors and, through computer simulations, we show that the CD errors are propagated and not negligible to the decoded qualities of the next frames within single GOP. Then, we propose an exponential-decaying model that describes well the characteristics of propagation/accumulation errors. Finally, it is shown that the proposed model can be effectively used for estimating the overall distortions incurred by the CD errors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.94-105
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• 2020

Recently, most studies of 3D printing in construction have focused on the development of 3D printers and materials suitable for construction 3D printers. In comparison, there has been little research on design support tools that enable representative BIM data of building modeling tools to be applied to 3D printing. In addition, existing 3D printing slicing programs are commercialized around manufacturing, showing that they are unsuitable for construction 3D printing. Therefore, this research aims to develop a design support tool for 3D printing for buildings. The developed design support tool was validated based on arbitrary BIM data. Verification showed that wall pattern generation was modeled accurately without errors, and a calculation of the construction period showed that the formula presented in this study was valid. Furthermore, the maximum length of the mesh split was set to 100mm to minimize errors when converting to STL files.

• Journal of Sensor Science and Technology
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• v.6 no.1
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• pp.6-15
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• 1997

This paper presents the multi-objective optimal design of thermopile sensor having beam or membrane structure. The thermopile sensor is composed of $Si_{3}N_{4}/SiO_{2}$ dielectric membrane, Al-polysilicon thermocouples and $RuO_{2}$ thin film for black body. The sensing method is based on the Seebeck effect which is originated from the temperature difference of the two positions, black body and silicon rim. The objective functions of the presented design are sensitivity, detectivity and thermal time constant. The modelling of the sensor is proposed including the package. The multi-objective optimization technique is applied to the design of the sensor not only inspecting the modelling equation but also simulating mathematical programming method. Especially, fuzzy optimization technique is adapted to get the optimal solution which enables the designer to reach the more practical solution. The design constraint of the voltage output originated from the change of the environmental temperature is included for practical use.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.1
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• pp.27-33
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• 2005

In this study, the process parameters in ceramics powder compaction are optimized for getting high relative densities of ceramic products. To find optimized parameters, the analytic models of powder compaction are firstly prepared by 2-dimensional rod arrays with random green densities using a quasi-random multiparticle array. Then, using finite element method, the changes in relative densities are analyzed by varying the size of Al₂O₃ particle, the amplitude of cyclic compaction, and the coefficient of friction, which influence the relative density in cyclic compactions. After the analytic function of relative density associated process parameters are formulated by aid of the response surface method, the optimal conditions in powder compaction process are found by the grid search method. When the particle size of Al₂O₃ is 22.5 ㎛, the optimal parameters for the amplitude of cyclic compaction and the coefficient of friction are 75 MPa and 0.1103, respectively. The maximum relative density is 0.9390.