• International Journal of Aeronautical and Space Sciences
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• v.16 no.2
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• pp.264-277
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• 2015

This article investigates various transcription techniques for the Legendre pseudospectral (PS) method to compare the pros and cons of each approach. Eight combinations from four different types of collocation points and two discretization methods for dynamic constraints, which differentiate Legendre PS transcription techniques, are implemented to solve a carefully selected test set of nonlinear optimal control problems (NOCPs). The convergence property and prediction accuracy are compared to provide a useful guideline for selecting the best combination. The tested NOCPs consist of the minimum time, minimum energy, and problems with state and control constraints. Therefore, the results drawn from this comparative study apply to the solution of similar types of NOCPs and can mitigate much debate about the best combinations. Additionally, important findings from this study can be used to improve the numerical efficiency of the Legendre PS methods. Three PS applications to the aerospace engineering problems are demonstrated to prove this point.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.6
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• pp.616-621
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• 2003

There are various Non-Destructive Evaluation (NDE) techniques used for measurement of residual stresses in material, such as magnetic methods, X-ray diffraction, Ultrasonic velocity measurement etc. The capabilities, applications and limitations of these techniques for evaluation of cold work/plastic deformation were studied and compared. Mild steel plates were subjected to different degree of cold deformation and were analyzed by Magneto-mechanical Acoustic Emission (MAE), Barkhausen Noise (BN) and magnetic properties (hysteresis loop parameters analysis). Further, these specimens were analyzed by X-ray diffraction and ultrasonic velocity measurements. The microhardness measurement and microstructure studies of these cold worked plates were also carried out. The results of all these studies and comparison of different techniques are discussed in this paper.

• Journal of the Korean Society for Library and Information Science
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• v.9
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• pp.99-118
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• 1982

This paper first reviews various techniques proposed for automatic indexing with special emphasis placed on statistical techniques. Frequency-based statistical techniques are categorized into the following three approaches for further investigation on the basis of index term selection criteria: term frequency approach, document frequency approach, and probabilistic approach. In the experimental part of this study, Pao's technique based on the Goffman's transition region formula and Harter's 2-Poisson distribution model with a measure of the potential effectiveness of index term were tested. Experimental document collection consists of 30 agriculture-related documents written in Korean. Pao's technique did not yield good result presumably due to the difference in word usage between Korean and English. However, Harter's model holds some promise for Korean document indexing because the evaluation result from this experiment was similar to that of the Harter's.

• Journal of KSNVE
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• v.8 no.6
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• pp.1121-1129
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• 1998

This research is concerned with the multiple PPF and the modified LQG controller design for active vibration control of intelligent structures. The intelligent structure is defined as the structure equipped with smart actuators and sensors. Various control techniques aimed for the piezoceramic sensors and actuators have been proposed for the active vibration control of smart structures and some of them prove their effectiveness experimentally. In this paper, the multiple PPF controller and the modified LQG controller are developed and applied to the smart grid structure. The multiple PPF control and the modified LQG control can be classified as the classical and the modern control techniques. respectively. The experimental results show that both control techniques are effective in suppressing vibrations. Two control techniques are compared with respect to the design process. the ease of implementation and the effectiveness

• Journal of Electrical Engineering and Technology
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• v.6 no.2
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• pp.182-191
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• 2011

Genetic algorithms (GA) and particle swarm optimization (PSO) are the most famous optimization techniques among various modern heuristic optimization techniques. These two approaches identify the solution to a given objective function, but they employ different strategies and computational effort; therefore, a comparison of their performance is needed. This paper presents the application and performance comparison of the PSO and GA optimization techniques for a static synchronous series compensator-based controller design. The design objective is to enhance power system stability. The design problem of the FACTS-based controller is formulated as an optimization problem, and both PSO and GA optimization techniques are employed to search for the optimal controller parameters.

• Mass Spectrometry Letters
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• v.6 no.4
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• pp.85-90
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• 2015

This article reviews recent analytical techniques using inductively coupled plasma-mass spectrometry (ICP-MS) immunoassay for clinical and bio analysis. We classified the techniques into two categories, direct and indirect analysis, which depend upon a guideline of whether tagging materials are used or not. Direct analysis is well known, and generally used in conjunction with various other techniques, such as laser ablation, chromatographic separations, etc. Recently, indirect analysis using tagging elements has intensively been discussed because of its importance in future applications to bio and clinical analysis, including environmental and food industries. The method has shown advantages of multiplex detection, excellent sensitivity, and short analysis time owing to signal amplification and magnetic separation. Now, it expands the application field from small biomolecules to large cells.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.53-63
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• 2013

It is well known that problem for contaminated soil with heavy metals is mainly produced from agricultural land around abandoned metal mine and the cost to solve them is much higher than those of water and air pollution in addition, it takes much more time to clarify the contaminated soil. Until now, economical and practical many techniques to remediate contaminated soils with heavy metals have been developed and proposed. Therefore, in this study, characteristic, merit and weakness for various techniques which are developing and commercializing recently in domestic/foreign country will be reviewed.

• Structural Engineering and Mechanics
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• v.32 no.4
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• pp.489-500
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• 2009

The aim of this paper is to compare wavelet, kurtosis and pseudofractal based techniques for structural health monitoring in the presence of measurement noise. A detailed comparison and assessment of these techniques have been carried out in this paper through numerical experiments for the calibration of damage extent of a simply supported beam with an open crack serving as an illustrative example. The numerical experiments are deemed critical due to limited amount of experimental data available in the field of singularity based detection of damage. A continuous detectibility map has been proposed for comparing various techniques qualitatively. Efficiency surfaces have been constructed for wavelet, kurtosis and pseudofractal based calibration of damage extent as a function of damage location and measurement noise level. Levels of noise have been identified for each technique where a sudden drop of calibration efficiency is observed marking the onset of damage masking regime by measurement noise.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1456-1458
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• 1999

As the system reliability of power supply is highly increased, we need distribution maintenance techniques without any power interruption. To meet such an increasing demand, a groat deal of hot line work on the high voltage overhead distribution lines has been carried out. In this regard, Hot line work techniques has being applied widely. However, hot line work techniques can not cover all kinds of work without interruption. To cope with those problems, the temporary power supply work technique such as bypass cable truck technique, temporary switch technique and mobile transformer technique was developed and applied. This paper presents the most optimal method according to distribution work contents through the comparison and analysis the characteristis and problems of the existing various work techniques. Also this paper suggested the countermeasers of the prsent problems.

• The KIPS Transactions:PartB
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• v.10B no.2
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• pp.157-162
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• 2003

In this paper, in-depth considerations are given to various techniques suggested for photographic 3D modelling and possible enhancements of the techniques are discussed. It is found that both the improvement of fundamental matrix estimation techniques and the stereo image rectification processing stage are necessary for more accurate 3D modelling.