• Journal of Korea Multimedia Society
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• v.8 no.6
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• pp.753-760
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• 2005

This paper introduces a variable step-size adaptive algorithm for blind source separation. From the frequency characteristics of mixed input signals, we need to adjust the convergence speed regularly in each frequency bin. This algorithm varies a step-size according to the magnitude of input at each frequency bin. This guarantee of the regular convergence in each frequency bin would become more efficient in separation performances than conventional fixed step-size FDICA. Computer simulation results show the improvement of about 5 dB in signal to interference ratio (SIR) and the better separation quality.

• Journal of the Korean Mathematical Society
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• v.55 no.4
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• pp.897-921
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• 2018

Given bounded pseudoconvex domains in 2-dimensional complex Euclidean space, we derive analytical and geometric conditions which guarantee the Diederich-$Forn{\ae}ss$ index is 1. The analytical condition is independent of strongly pseudoconvex points and extends $Forn{\ae}ss$-Herbig's theorem in 2007. The geometric condition reveals the index reflects topological properties of boundary. The proof uses an idea including differential equations and geometric analysis to find the optimal defining function. We also give a precise domain of which the Diederich-$Forn{\ae}ss$ index is 1. The index of this domain can not be verified by formerly known theorems.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.283-286
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• 2004

This paper refers and implements XML Web services, which supports networked interchanges of moving object information. XML Web services are expected to be fundamental building blocks in the move to distributed computing on the Internet. As an interchange format, GML encodes semantics, syntax, and schema of geospatial and geoprocessing-related information resources. It can give great benefits to utilize raw data easily as an XML encoding format does. This paper proposes a full coverage of interoperable location trajectory services consisting of 3 independent modules: a moving object database, a data processing server, and a web services interface module. For communications, SOAP protocols and WSDL documents are used, which can guarantee an interoperability of a system regardless of different platforms and service channels. This paper also designs a GML data format that represents location information of probe cars.

• International Journal of Control, Automation, and Systems
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• v.3 no.spc2
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• pp.302-307
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• 2005

A novel neuro controller based simple neuro-structure with modified error function is introduced in this paper. This controller consists of two independent controllers, known as the voltage regulator and the angular controller. The voltage regulator is used to modify terminal voltage for the purpose of tracking a reference voltage. The angular controller is utilized to guarantee the stability of the system. In this structure each neuron uses a linear hard limit activation function that depends on the controlled variable and its derivatives. There is no need for parameter identification or any off-line training data. Two proposed controllers are merged by a smooth switch to build a complete controller. The effectiveness of the proposed novel control action is demonstrated through some computer simulations on a Single-Machine Infinite-Bus (SMIB) power system.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.394-396
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• 2005

In this paper, we propose an adaptive tracking control method of a mobile manipulator for contour following with a kinematic model to have several unknown dimension parameters. Moreover, we will use the decentralized control method to design two independent controllers for two subsystems. The proposed controllers in this paper are based on the Lyapunov function in order to guarantee the stability of whole system for contour following task. The updated laws are also designed to estimated the unknown dimension parameters. Finally, the simulation results are presented to show the validity of the proposed controllers in this paper.

• ETRI Journal
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• v.21 no.4
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• pp.29-40
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• 1999

In this paper, we show the robustness of a proposed system using both a frequency diversity and a time diversity effect when the channel assumptions are relaxed such that all sub-bands are not independent fading. We take time-repetition coding with interleaving such that the repetition code symbols are spaced sufficiently far apart to guarantee time diversity. We also incorporate offset multicarriers into a proposed multicarrier DS-CDMA system in a different way compared to that of [10] to reduce the total multiple access interference. When we take a convolutional encoder instead of a time-repetition encoder, and again use both time diversity and frequency offset, then we can obtain the significant performance gain.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.108-111
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• 2004

Structural dynamic characteristics and aeroelastic stability of a small-scale bearingless rotor system have been investigated. A flexbeam is one of the most important component of bearingless hub system. It must have sufficient torsional flexibility as well as baseline stiffness in order to produce feathering motion. In the present paper, a cross-shaped composite flexbeam has been proposed for a guarantee of torsional flexibility and flapwise and lagwise bending stiffness. One dimensional elastic beam model was used for the construction of a structural model. Equivalent isotropic sectional stiffness was used in the blade model, and the flexbeam was regarded as anisotropic; which has ten independent stiffness quantities. CAMRAD II has been used for the analysis of structural dynamic characteristics of the bearingless rotor system. Rotational natural frequencies and aeroelastic stability at hovering have been investigated. Analysis result shows that the cross-shaped flexbeam has the rotational natural frequency tuning capacity.

• The Korean Journal of Community Living Science
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• v.26 no.1
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• pp.191-206
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• 2015

This study investigates the differences in retirement preparation and asset type in the elderly life of employees in their forties and fifties. Retirement preparation showed a score of 3.30, and the emotional preparation dimension of retirement preparations showed a slightly higher score. The retention of guarantee assets(insurance and, national pension) scored higher than other types of assets. There was a high correlation between economic preparation and the type of asset retention. According to the hierarchical regression analysis, economic preparation, monthly income, home ownership, and the education level had significant effects on assets retention, and the explanatory power of these independent variables was 39.7%.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.183-186
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• 2003

In this paper, we propose a DRM(Digital Rights Management) system for streaming media which can not only protect streamed MPEG-4 content but be easily integrated with existing MPEG-4 streaming system. To protect MPEG-4 media more effectively and more securely, encryption should be considered on encoding phase and also streaming server should be designed to support DRM. However that means it cannot support existing streaming system. Our approach is to design a DRM system independent to the streaming server. So, we used an encryption method which can be applied to compressed MPEG-4. The processing time of decryption in client system must be minimized to guarantee the QoS of streaming service. To satisfy this requirement, it is essential to analyze the effect of DRM on performance. We made some performance test and present the result. Also, we apply proposed system to ISMA(The Inter net Streaming Media Alliance) streaming system which is open standard for MPEG-4 media streaming.

• Communications of the Korean Mathematical Society
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• v.14 no.2
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• pp.337-352
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• 1999

In this paper we find a geometric condition for the weaker principle of spatial averaging (PSA) for a class of polyhedral domains. Let \ulcorner be a polyhedron in R\ulcorner, n$\leq$3. If all dihedral angles of \ulcorner are submultiples of $\pi$, then there exists a parallelopiped \ulcorner generated by n linearily independent vectors {\ulcorner}\ulcorner in R\ulcorner containing \ulcorner so that solutions of $\Delta$u+λu=0 in \ulcorner with either the boundary condition u=0 or ∂u/∂n=0 are expressed by linear combinations of those of $\Delta$u+λn=0 in \ulcorner with periodic boundary condition. Moreover, if {\ulcorner}\ulcorner satisfies rational condition, we guarantee the weaker PSA for the domain \ulcorner.