• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.3A
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• pp.196-204
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• 2002

The Sinusoidal Transform Coding(STC) is a vocoding scheme based on a sinusoidal model of a speech signal. The low bit-rate speech coding based on sinusoidal model is a method that models and synthesizes speech with fundamental frequency and its harmonic elements, spectral envelope and phase in the frequency region. In this paper, we propose the 2.4kbps low-rate speech coding algorithm using the sinusoidal model of a speech signal. In the proposed coder, the pitch frequency is estimated by choosing the frequency that makes least mean squared error between synthetic speech with all spectrum peaks and speech synthesized with chosen frequency and its harmonics. The spectral envelope is estimated using SEEVOC(Spectral Envelope Estimation VOCoder) algorithm and the discrete all-pole model. The phase information is obtained using the time of pitch pulse occurrence, i.e., the onset time, as well as the phase of the vocal tract system. Experimental results show that the synthetic speech preserves both the formant and phase information of the original speech very well. The performance of the coder has been evaluated in terms of the MOS test based on informal listening tests, and it achieved over the MOS score of 3.1.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.3
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• pp.27-32
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• 2008

Bone is a self-assembly material. It is known that the low amplitude and high frequency mechanical stimulus, which is much less amplitude but higher frequency than those induced by the normal activity, can induce new bone formation. The vibrating resonance is employed to elucidate why new bone is formed by this kind of mechanical stimulus. For example, as 30 Hz and $5{\mu}{\epsilon}$ mechanical stimulus is applied at the wall of canaliculus (the tiny tube type pathway of bone fluid flow and the diameter of canaliculus is less than 200nm), the osteocytic cell membrane experiences $1,000{\mu}{\epsilon}$ strain due to the vibrating resonance. Two experiments will follow after this pilot study; (1) observing the MAPK pathway of osteocytes by using in-vitro cell culture and (2) visualizing the actin filament network in the osteocytes by using the imaging technique, such as confocal laser scanning microscope.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5135-5142
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• 2011

A flexible mechanism is proposed in this paper to improve the dynamic response performance of a traffic flow control system in an urban area. The roads, vehicles, and traffic control systems are all modeled as intelligent systems, wherein a wireless communication network is used as the medium of communication between the vehicles and the roads. The necessary sensor networks are installed in the roads and on the roadside upon which reinforcement learning is adopted as the core algorithm for this mechanism. A traffic policy can be planned online according to the updated situations on the roads, based on all the information from the vehicles and the roads. This improves the flexibility of traffic flow and offers a much more efficient use of the roads over a traditional traffic control system. The optimum intersection signals can be learned automatically online. An intersection control system is studied as an example of the mechanism using Q-learning based algorithm, and simulation results showed that the proposed mechanism can improve the traffic efficiency and the waiting time at the signal light by more than 30% in various conditions compare to the traditional signaling system.

• Journal of the Institute of Convergence Signal Processing
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• v.22 no.2
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• pp.51-56
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• 2021

The brachial systolic blood pressure and pulse pressure are the predictors of cardiovascular disease in individuals over 50 years of age. As the stiffness increases, the reflex amplitude and pressure in the late systole increase, resulting in an increase in left ventricular load and myocardial oxygen demand. Therefore, it is necessary to study how stiffness affects blood pressure. In this study, the blood pressure pulse waves were measured before and after taking the drug, and the blood pressure pulse wave was measured before and after myocardial heart transplantation in patients with heart failure. The correlation between R, L, and C components of the Windkessel model was estimated by increasing blood pressure. As a result of modeling the parameters of the Windkessel model using the curve fitting method, the increase in blood pressure and decrease in systolic rise time were due to the increase in the L component in the RLC Windkessel model. Among the various mechanical characteristics of blood vessels, the most important parameter affecting high BP waveform is the inertance.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.1
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• pp.15-20
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• 2022

An improvement of computational resources with a large scale cluster service is available to the individual person, which has been limited to the original industry and research institute. Therefore, the application of powerful computational resources to the engineering design has been increased fast. In naval and marine industry, the application of Computational Fluid Dynamics, which requires a huge computational effort, to a design of ship and offshore structure has been increased. Floating bodies such as the ship or offshore structure is exposed to ocean waves, current and wind in the ocean, therefore the precise modelling of those environmental disturbances is important in Computational Fluid Dynamics. Especially, ocean waves has to be nonlinear rather than the linear model based on the superposition due to a nonlinear characteristics of Computational Fluid Dynamics. In the present study, a fast reconstruction technique is suggested and it is validated from a series of simulations by using the Computational Fluid Dynamics.

• Journal of the Institute of Convergence Signal Processing
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• v.24 no.4
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• pp.186-191
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• 2023

Data processing techniques play a critical role in decision-making, including handling missing and outlier data, prediction, and recommendation models. This requires a clear explanation of the validity, reliability, and accuracy of all processes and results. In addition, it is necessary to solve data problems through explainable models using decision trees, inference, etc., and proceed with model lightweight by considering various types of learning. The multi-layer mining classification method that applies the sixth principle is a method that discovers multidimensional relationships between variables and attributes that occur frequently in transactions after data preprocessing. This explains how to discover significant relationships using mining on transactions and model the data through regression analysis. It develops scalable models and logistic regression models and proposes mining techniques to generate class labels through data cleansing, relevance analysis, data transformation, and data augmentation to make explanatory decisions.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.9
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• pp.107-114
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• 2004

This paper presents block and timing diagrams of the DWA(Data Weighted Averaging) to optimize a feedback time delay of the sigma-delta modulator. Through the MATLAB modeling, the optimized coefficients of the integrators are obtained to design the modulator. The fully differential SC integrators, feedback DAC, 9-level quantizer, and DWA are designed by considering the nonideal characteristics of the modulator. The designed third-order multibit modulator is fabricated in a 0.35${\mu}{\textrm}{m}$ CMOS process. The modulator achieves 75dB signal-to-noise ratio and 74dB dynamic range at 1.2Vp-p 825kHz input signal and 52.8MHE sampling frequency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6B
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• pp.1042-1047
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• 1999

In this paper, two kinds of digital predistorters are proposed and their performances are analyzed in order to minimize ACI and SNR degradation caused by nonlinearly amplified TC-16QAM signal and to transmit high speed data in power and bandwidth limited land mobile satellite channel. Our simulation results show that LUT predistorter reduces the out-of-band ACI more efficiently as compared to intersymbol interpolated predistorter. Regarding the reduction of in-band SNR and total power intersymbol interpolated predistorter outperforms LUT predistorter. In the simulation mobile satellite channel and nonlinear HPA are modeled by Rician channel and Fujitsu SSPA, respectively.

• Korean Journal of Optics and Photonics
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• v.12 no.3
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• pp.205-211
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• 2001

We propose a constant inversion black box model of erbium-doped fiber amplifiers (EDFAs) for exact performance predictions for EDFAs operated in the gain-flattened condition. The validity of the newly proposed model was experimentally verified by predicting the performance of EDFAs for the L band, within 1.9% required pump power discrepancy. The role of ion pairing effects on the power conversion efficiency is also discussed. ussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.161-166
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• 2005

The synthesis procedure of Marchand balun using planar coupled-line is presented. The design limitations of this type of balun have been described before its synthesis procedure. The balun has equi-ripple passband responses and balanced output without fourth balanced transmission line which is difficult to implement with conventional planar topology. As an example, 2:1 Marchand balun is designed and its momentum simulation result show good verification fur this methodology.