• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.3
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• pp.281-285
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• 2008

Eigenvalue reduction schemes approximate the lower eigenmodes that represent the global behavior of the structures. In the previous study, we proposed a two-level condensation scheme (TLCS) for the construction of a reduced system. And we have improved previous TLCS with combination of the iterated improved reduced system method (IIRS) to increase accuracy of the higher modes intermediate range. In this study, we apply previous improved TLCS to multi-level sub-structuring scheme. In the first step, the global system is recursively partitioned into a hierarchy of sub-domain. In second step, each uncoupled sub-domain is condensed by the improved TLCS. After assembly process of each reduced sub-eigenvalue problem, eigen-solution is calculated by Lanczos method (ARPACK). Finally, Numerical examples demonstrate performance of proposed method.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.129-134
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• 1994

A Laser Cutter is designed for the precise fabrications in the shipyards recently. The cutter is a gantry type one with specified functions of movability and strength in order to satisfy the workability. The gantry frame should move with a certain velocity in a relatively short time for the proper cutting of the object materials. The gantry is fitted with ball screw and the acceleration field is formed by actuating this ball screw. The relative displacement should be within the allowable design criteria to make sure the precise cutting of the materials by the laser. In this paper, modal and structural analysis for a Laser Cutter which is commonly used in the shipyards, is carried out to check the design criteria of the system. The system is modeled by placing the proper shell and soils finite elements and fictitious mass properties to represent the real one. The way how to extract the loading conditions based on the given velocity criteria of the system is presented. Static structural analysis is performed and the results came out as expected. Modal analysis for finding eigen-values and mode shapes of the system is performed and it is shown that the time dependent dynamic analysis is unnecessary for this system for its operating circumstances.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.403-408
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• 2005

The techniques of estimating angle of arrival(AOA) have played a key role for enhancement of wireless communications using array antennas. Among those techniques, the superresolution algorithms, such as MUSIC and ESPRIT, calculate the covariance matrix of the array output vectors which are observed at the array antennas, and then by using eigen-decomposition of the covariance matrix, they estimate AOAs of the received signals with high accuracy. However, superresolution algorithms based eigenvalue decomposition fails to estimate AOAs under multipath environments. Under multipath environments, it is difficult to estimate AOAs of the received signals due to coherency and high-correlation. To resolve coherent signals, the covariance matrix is calculated by using the conventional spatial smoothing technique, and then the techniques based on eigen-descomposition is applied. The result of the conventional spatial smoothing technique, however, is obtained at the cost of losing effective spatial aperture. Moreover, the conventional technique ignores any information in the cross-correlations of the array outputs the subarrays. As the result, the performance for AOA estimation is degraded. In this paper, we propose a new spatial smoothing technique, which consider the cross-correlation for subarrays. By computer simulation, the AOA estimation performance of the proposed method is compared with the conventional method and evaluated.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.34-40
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• 2012

A pressure control law to regulate pressure of gas generator is suggested. To design a model based control law, the governing equation which consists of Robert and conservation equation is built and verified through the ground burning test. PID and nonlinear adaptive control laws are designed to analyze the loop response characteristics under the system which has varying eigen properties arisen from combustion volume change. It is suggested that new approach, gain scheduling design, is required to overcome the defects identified from numerical simulation results of the two control laws. The newly suggested scheme shows good control performance even under disturbances and measurement noise.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.6
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• pp.267-275
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• 2020

In the event of an earthquake, non-structural components require seismic performance to ensure evacuation routes and to protect lives from falling non-structural components. Accordingly, the seismic design code proposes horizontal force for the design and evaluation of non-structural components. Ground motion observed on each floor is affected by a building's eigen vibration mode. Therefore, the earthquake damage of non-structural components is determined by the characteristics of the non-structural component system and the vibration characteristics of the building. Floor response spectra in the seismic design code are estimated through time history analysis using seismic waves. However, it is difficult to use floor response spectra as a design criterion because of user-specific uncertainties of time history analysis. In addition, considering the response characteristics of high-rise buildings to long-period ground motions, the safety factor of the proposed horizontal force may be low. Therefore, this study carried out the horizontal force review proposed in the seismic design code through dynamic analysis and evaluated the floor response of seismic waves considering buildings and predominant periods of seismic waves.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1439-1446
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• 2011

This paper describes the algorithm that lowers the dimension, maintains the object recognition and significantly reduces the eigenspace configuration time by combining the higher correlation feature information and Principle Component Analysis. Since the suggested method doesn't require a lot of computation than the method using existing geometric information or stereo image, the fact that it is very suitable for building the real-time system has been proved through the experiment. In addition, since the existing point to point method which is a simple distance calculation has many errors, in this paper to improve recognition rate the recognition error could be reduced by using several successive input images as a unit of recognition with K-Nearest Neighbor which is the improved Class to Class method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.618-623
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• 2011

A pressure control law to regulate pressure of gas generator is suggested. To design a model based control law, the governing equation which is consisted of Robert and conservation equation is built and verified through the ground burning test. PID and nonlinear adaptive control laws are designed to evaluate the loop response characteristics under the system which has varying eigen properties as combustor volume is increased. It is suggested that new approach, gain scheduling design, is required to overcome the defects identified from numerical simulation results of the two control laws. The newly suggested scheme showed good control performance even under disturbances and measurement noise.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.137-142
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• 2013

Direction of arrival is estimating for desire signal direction among received signal on antenna in spatial. In this paper, we were an estimation a receiving signal direction of arrival using multi beam forming in radar. We proposed, by signal direction of arrival estimation method, an algorithm which combine spatial correlation matrix weight value and beam steering algorithm in this paper. Through simulation, we were analysis a performance to compare general algorithm and proposal algorithm. In direction of arrival estimation, proposed algorithm is effectivity to decrease processing time because it is not doing an eigen decomposition. We showed that proposal algorithm improve more target estimation than general algorithm.

• 전자공학회논문지 IE
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• v.45 no.3
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• pp.42-49
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• 2008

This paper proposes a new beamforming algorithm to select beamforming gain or/and diversity gain in CDMA2000, W-CDMA, W-LAN channel according to signal environment on the multipath. In this paper, we present the criteria to obtain deversity gain at any point that based on quantized experimental value. Proposed method proposes represents a performance better than conventional algorithm adopting the largest two eigenvector when angle spread is exit. From the results of performance analysis through various simulation, it is confirmed that proposed method is far superior about $3{\sim}4$ times compare to conventional method in signal environment.

• Journal of Families and Better Life
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• v.6 no.1
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• pp.205-221
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• 1988

The purpose of this study is to classify several variable which were assumed to have relationship with the college students behavior of Hyo, to see their possible correlation with demographic characteristics, and to proved some useful data for their possible correlation with demographic characteristics. and to provide some useful data for their sound value system. The data for this study was obtained form the survey of the 477 students who reside in the city of Seoul by using questionnaire methods. The frequency of variables was statistically analyzed to see the general character of the samples and factor analysis was made for classification of the college student's behavior of Hyo. In order to study th characteristic of demographic variables, t-test and ANOVA were conducted The major findings of this study can be summarized as follows. 1) As the result of factor analysis about behavior of Hyo, six factors (Which Eigen value was above 1.0) out of 64 questions were extracted : 'respect' familiarity' 'family consciousness' 'serve' self-preservation, establishmence of them-selves in life' and 'self-reliance' were selected. 2)In general, it can be said that the college students' behavior of Hyo varies by demographic variables. 3) By surveying the level of actualizing Hyo of the college students' all of factors ranged from 'the middle' to 'the high level'. The result confirmed that students fulfilled the behavior of Hyo to their parents in all items.