• Journal of IKEEE
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• v.6 no.2 s.11
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• pp.111-118
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• 2002

In this paper, we present a variable block method to reduce additive computational requirements in determining step-size of variable step-size LMS (VS-LMS) algorithms. The block length is inversely proportional to the changing of step-size in VS-LMS algorithm. The technique reduces computational requirements of the conventional VS-LMS algorithms without a degradation of performance in convergence rate and steady state error. And a method for deriving initial step-size, when the input is zero mean, white Gaussian sequence, is proposed. For demonstrating the good performances of the proposed method, simulation results are compared with the conventional variable step-size algorithms in convergence speed and computational requirements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1121-1127
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• 2014

In this paper, a planar frequency reconfigurable antenna is proposed with variable capacitors. The proposed one is designed with a planar monopole, and varies resonant frequencies by variable capacitive loading of a varactor diode. The equivalent circuit and electromagnetic(EM) simulation are utilized for the analysis at the variable characteristic design of the antenna, and the same radiation performance. The implemented frequency variable monopole antenna has been verified by comparing prototypes with designed capacitors and ones with biased varactor diodes. The proposed antenna has presented the resonant frequency variations from 2.25 GHz to 2.42 GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1053-1060
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• 2016

This paper proposes an adaptive equalizer with the digitally controlled active variable capacitor. An equalizing amplifier consists of a main amplifier and a source degeneration RC filter which is implemented using the digitally controlled active variable capacitor for area efficiency and linear loss compensation. The active capacitor changes its capacitance by the amplifier gain control, which is based on miller effect. In the simulated results, the proposed equalizer compensates the high frequency loss and extends the data eye width from 0.31 UI to 0.64 UI.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.1-5
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• 2006

Birds and insect in nature morph their mean camberline shapes to obtain both lift and thrust simultaneously. Previous unsteady thin airfoil theories were derived mainly for a rigid flapping airfoil. An extended unsteady thin airfoil theory for a deformable airfoil is required to analyze the unsteady two-dimensional aerodynamic characteristics of a biomorphing wing. Theodorsen's approach is extended to calculate the unsteady aerodynamic characteristics of a biomorphing airfoil. The mean camberline of the airfoil is represented as a polynomial. The unsteady aerodynamic characteristics of the morphing airfoil are represented as noncirculatory and circulatory terms. Present theory can be applied to the unsteady aerodynamic analysis of a flapping biomorphing airfoil and the aeroelastic analysis of a morphing wing.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.127-134
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• 2015

In this note, a continuous sliding surface transformed variable structure systems by the saturation function is presented for MIMO uncertain linear plants. A discontinuous sliding surface transformed VSS is proposed theoretically. The closed loop exponential stability together with the MIMO existence condition of the sliding mode on the predetermined sliding surface is investigated. For practical applications, a continuous approximation of the discontinuous VSS is made by means of the saturation function. The discontinuity of the control input as the inherent property of the VSS is much improved in view of the practical aspects. Through a design example and simulation studies, the usefulness of the proposed continuous transformed VSS controller is verified.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.23-32
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• 2012

The present study is aimed to develop an integrated performance analysis approach for the application of a compressor with variable inlet guide vane (VIGV) and vairable stator vane (VSV) in a small turbofan engine. For the integrated analysis approach, an engine performance analysis program, NPSS and a computer program used for predicting of axial flow compressor performance based on stage stacking method, STGSTK were linked with an optimisation package, Isight. This enables off-design performance analysis for the turbofan engine with VIGV and VSV hence provides the capability to predict stable operation condition of the engine with acceptable surge margin.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.9
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• pp.235-242
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• 2021

Most data scrambling schemes generate pure random codes. Unlike these schemes, we propose a variable density scrambling scheme (VDSC) that differentiates densities of generated codes. First, we describe conditions and methods to translate plain codes to cipher codes with different densities. Then we apply the VDSC to flash memory such that preferred cell states occur more than others. To restrain error rate, specifically, the VDSC controls code densities so as to increase the ratio of center state among all possible cell states in flash memory. Scrambling experiments of data in Windows and Linux systems show that the VDSC increases the ratio of cells having near-center states in flash memory.

• Journal of Adhesion and Interface
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• v.24 no.2
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• pp.41-53
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• 2023

The deformable devices refer to the devices that can maintain their initial performance even when stretched or bent. Among the materials used as conductor in deformable devices, Ga-based liquid metal is one of the most promising materials because it can provide not only high conductivity and deformability but also low toxicity. In this paper, we introduce Ga-based liquid metals and then discuss the recent research trend in deformable devices composed of Ga-based liquid metal.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.2 s.314
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• pp.27-36
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• 2007

Changeable biometrics identify a person using transformed biometric data instead of original biometric data in order to enhance privacy and security in biometrics when biometric data is compromised. In this paper, a novel scheme which generates changeable face templates for statistical appearance-based face recognition is proposed. Two different original face feature vectors are extracted from two different appearance-based approaches, respectively, each original feature vector is normalized, and its elements are re-ordered. Finally a changeable face template is generated by weighted addition between two normalized and scrambled feature vectors. Since the two feature vectors are combined into one by a two to one mapping, the original two feature vectors are not easily recovered from the changeable face template even if the combining rule is known. Also, when we need to make new changeable face template for a person, we change the re-ordering rule for the person and make a new feature vector for the person. Therefore, the security and privacy in biometric system can be enhanced by using the proposed changeable face templates. In our experiments, we analyze the proposed method with respect to performance and security using an AR-face database.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.115-127
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• 2008

The component for satisfying several domain requirements must be developed to support variety. But, when the application is developed using the component, it happens other requirements. So, it is difficult to design component to satisfy severaldomain requirements. Also, it is impossible to support the special business logic. As this problem, the component must provide to the white-box component, it is not the black-box component. So, in this paper, we propose the variability design technique and the customization technique using the design technique that can support the various requirements. This technique is not focus on designing the component to analyze various domains. The variability of the component is designed to the initial variability in the component development phase and we use the customization technique for applying the variability to developing application. The variability can be re-designed during developing the application to use the component applying the variability. The variability of the component is evolved and the generation of the component is increased via the iteration Generally, the range of the component variability is classified the function modification within the component and the component internal structure modification as requirements in the component outside. As the range of the variability, we propose the variability design technique of the behavior and the message flow. This paper proposes a message flow design technique for modifying function call.