• Journal of Powder Materials
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• v.10 no.1
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• pp.51-56
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• 2003

To investigate the effect of the parameters of the plasma arc discharge process on the particle formation and particle characteristics of the iron nano powder, the chamber pressure, input current and the hydrogen volume fraction in the powder synthesis atmosphere were changed. The particle size and phase structure of the synthesized iron powder were studied using the FE-SEM, FE-TEM and XRD. The synthesized iron powder particle had a core-shell structure composed of the crystalline $\alpha$-Fe in the core and the crystalline $Fe_3O_4$ in the shell. The powder generation rate and particle size mainly depended on the hydrogen volume fraction in the powder synthesis atmosphere. The particle size increased simultaneously with increasing the hydrogen volume fraction from 10% to 50%, and it ranged from about 45nm to 130 nm.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.110-110
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• 2001

By the state transformation including independent outputs functions, a nonlinear process model can be decomposed into two subsystems; the one(design model) is described in output variables as new states and used for control system synthesis and the other(disturbance model) is described in the original unavailable states and its couplings with the design model are treated as uncertain time-varying parameters in the design model. Its existence with respect to the design model is ignored. So, the design model is and uncertain time-variant system. Control synthesis based on a reduced design model is a combined form of a time-variant input-output linearization with parameter estimation. The parameter estimation is also based on the design model and it gives the parameter estimates such that the estimated outputs follow the actual outputs in a specified way. The disturbances form disturbance model and as well all the other uncertainties affecting the outputs will be reflected into the estimated parameters used in the linearizing control law.

• Journal of the Korean Institute of Telematics and Electronics
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• v.18 no.1
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• pp.41-50
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• 1981

The human speech contains many redundancies. To economize communication channel or memory size for a computerized synthesis of human voices, it is necessary to compress the data before sending. We have treated human speech organ as an eighth order dynamic system which is time varying as the person speaks. Using an anaylyzer of our design, each eight parameters are obtained for the vowels [아], [어], [오], [우], [으], [이], [애], and (외) of korean language with considerable discrepancies between persons. Supplying those parameters to a synthesizer which we have made, we have sucoeeded in the simulation of human speech for the above mentioned vowels of Korean language and observed that they bear all the features of the original speakers.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.7
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• pp.1025-1035
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• 1995

In this paper, we realize a real time digital FM synthesizer based on genetic algorithm using a general purpose digital signal processor. Especially, we synthesize diverse music sounds nicely using a synthesis model consisting of a single modulator and multiple carriers. Also we present genetic algorithm-based technique which determines optimal parameters for reconstruction through FM synthesis of a sound after analyzing the spectrum of PCM data as a standard music sound using FFT. Using the suggested parameter extractiuon algorithm, we extract parameters of several instruments and then synthesize digital FM sounds. To verify the validity of the parameter extraction algorithm as well as realization of a real time digital music synthesizer, the evaluation is first done by listening the sound directly as subjective test. Secondly, to evaluate the synthesized sound objectively with an engineering sense, we compare the synthesized sound with an original one in a time domain and a frequency domain.

• Speech Sciences
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• v.8 no.1
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• pp.7-19
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• 2001

The acoustic parameters of nine Korean numbers were analyzed by Praat, a speech analysis software, and synthesized by SenSynPPC, a Klatt formant synthesizer. The overall intensity, pitch and formant values of the numbers were modified dynamically by a step of 1 dB, 1 Hz and 2.5% respectively. The study explored the sensitivity of listeners to changes in the three acoustic parameters. Twelve subjects (male and female) listened to 390 pairs of synthesized numbers and judged whether the given pair sounded the same or different. Results showed that subjects perceived the same sound quality within the range of 6.6 dB of intensity variation, 10.5 Hz of pitch variation and 5.9% of the first three formant variations. The male and female groups showed almost the same perceptual ranges. Also, an asymmetrical structure of high and low boundary was observed. The ranges may be applicable to the development of a speaker identification system while the method of synthesis modification may apply to its evaluation data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.136-145
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• 2002

In this paper, we facilitate the analysis of 1D PBG structure using a ABCD matrix formulation after converting field parameters into circuit parameters. Dispersion diagrams for an infinite 1D PBG structure are derived and compared with the frequency responses for a finite structure (N=10). When the proposed method is adopted, the analysis and synthesis of 1D PBG structures become very convenient.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.420-421
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• 2006

In the present study, ultrafined Zr-V-Fe based alloy powder prepared by a plasma arc discharge process with changing process parameters. The chemical composition of synthesized powder was strongly influenced by the process parameters, especially the hydrogen volume fraction in the powder synthesis atmosphere. The synthesized powder had an average particle size of 50 nm. The synthesized Zr-V-Fe based particles had a shell-core structure composed of metal in the core and oxidse in the shell.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.126-126
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• 2000

In this paper, we provide an approach of controller synthesis for input-saturated linear systems by a linear parameter varying (LPV) framework. Using directly the saturation nonlinearity as scheduling parameters, we propose an LPV-stabilizer with parameter-dependent dynamic state-feedback controller concept. Especially, the synthesis conditions are formulated in terms of linear matrix inequalities (LMIs) that can be solved very efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.99-102
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• 2002

The BSCCO superconductor materials of using Self-propagating High-temperature Synthesis (SHS) were studied. Mechano-chemical activation - as a pre-treatment of the reactants mixture - strongly influences the kinetic parameters, the reaction mechanism, and the composition and structure of the final product. In this paper as an effort for fabricating the SHSed BSCCO superconductor powder SHS method was considered to application in the synthesis of superconducting materials.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.87.2-87
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• 2001

By the state transformation including independent outputs functions, a nonlinear process model can be decomposed into two subsystems; the one(design model) is described in output variables as new states and used for control system synthesis and the other(disturbance model) is described in the original unavailable states and its couplings with the design model are treated as uncertain time-varying parameters in the design model. Its existence with respect to the design model is ignored. So, the design model is an uncertain time-variant system. Control synthesis based on a reduced design model is a combined ...