• Proceedings of the Korean Statistical Society Conference
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• 2000.11a
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• pp.235-240
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• 2000

In this paper a test of fit for exponentiality and we propose the estimator of Kullback-Leibler Information functions using the data from accelerated life tests. This acceleration model is assumed to be a tampered random variable model. The procedure is applicable when the exponential parameter based on the data from accelerated life tests is or is not specified under null hypothesis. Using Simulations, the power of the proposed test based on use condition of accelerated life test under alternatives is compared with that of other standard tests in the small sample.

• The Journal of the Acoustical Society of Korea
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• v.16 no.2E
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• pp.14-20
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• 1997

The future teleconferencing systems will need an appropriate system which controls properly the acoustic echo for the convenient communication. The conventional acoustic echo cancellation algorithms involve large adaptive filters identifying the impulse response of the echo path. The use of adaptive IIR filters appears to be a reasonable way to reduce computational complexity. Effective cancellation of acoustic echo presented in teleconferencing system requires that adaptive filters have a rapid convergence speed. One of the main problems of acoustic echo cancellation techniques is that the convergence properties degrade for an highly correlated signal input such as speech signals. By the way, the introduction of linear prediction filers onto the structure of the acoustic echo cancellation represents one approach to decorrelate the speech signal. And variable step-size LMS algorithm improves the convergence speed through a little increasing of computational complexity. In this paper, we applied these two methods to the acoustic echo canceller(AEC) and showed that these methods have better performances than the conventional AEC.

• The Korean Journal of Applied Statistics
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• v.13 no.2
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• pp.563-573
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• 2000

In this paper, we propose three estimators of Kullback-Leibler Information functions using the data from accelerated life tesb. This acceleration model is assumed to be a tampered random variable model. Some asymptotic properties of proposed estimators are proved. Simulations are performed for comparing the small sample properties of the proposed estimators under use condition of accelerated life test.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.70-72
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• 2009

In this paper, nonlinear active noise control(ANC) of a 3rd-order Volterra system, which is robust to background noise variation, is proposed along with a variable step-size Gauss-Seidel pseudo affine projection(VSSGS-PAP) algorithm. Simulation results demonstrate that the proposed approach yields better nonlinear ANC performance in a background noise variation environment, compared with the conventional methods for the nonlinear ANC.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.369-373
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• 2005

This paper proposes a variable step size parameter method in frequency domain ICA (FDICA). The FDICA and the temporal analysis (TA) algorithm are experimented for blind source separation (BSS). This paper will compare the separation qualities of these two algorithms in various reverberation environments. Furthermore, it is shown that the proposed technique has the better separation performance than those of two methods especially in recorded data.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.2
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• pp.121-128
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• 2018

This work proposes a simple control method of a buck-type active power decoupling circuit that can minimize the ripple values in the dc link voltage. The proposed method utilizes a simplified duty calculation method and an optimal compensation gain tracking algorithm with variable-step approach. Thus, the dc link voltage ripple can be effectively reduced through the proposed method along with rapid response in tracking the optimum compensation gain. Moreover, the proposed method has better dynamic responses in the load fluctuation or abnormal situation. MATLAB/Simulink simulation and hardware-in-the-loop-simulation(HILS)-based experimental results are presented to validate the effectiveness of the proposed control method.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.267-268
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• 2016

This study aimed to examine the therapeutic effects of backward walking. The subjects were randomly assigned to an experimental group of 16 subjects and a control group of 17 subjects. All subjects walked barefoot for twenty minutes on the treadmill (HM50EX, Daeho, Korea) for five times per week for total four weeks. The average gait velocities of subjects were 3 km/h on a slope of 10%. The experimental group walked back and the control group walked forward. The experimental group showed significant increments in variable of medial-lateral, anterior-posterior, step length, velocity compared to the pre-intervention results. In addition, the control group showed significant increments in the anterior-posterior, velocity compared to the pre-intervention results. Significant differences in the post-training gains in variable of anterior-posterior, step length, velocity were observed between the experimental group and the control group. There were positive effects of backward walking on their gait and balance ability after intervention.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.3
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• pp.96-105
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• 1992

The use of fixed-point digital signal processors, such as the TMS 320C25, requires scaling of data at each arithmetic step to prevent overflows while keeping the accuracy. A software which automatizes this process is developed for TMS 320C25. The programmers use a model of a hypothetical floating-point digital signal processor and a floating-point format for data representation. However, the program and data are automatically translated to a fixed-point version by this software. Thus, the execution speed is not sacrificed. A fixed-point variable has a unique binary-point location, which is dependent on the range of the variable. The range is estimated from the floating-point simulation. The number of shifts needed for arithmetic or data transfer step is determined by the binary-points of the variables associated with the operation. A fixed-point code generator is also developed by using the proposed automatic scaling software. This code generator produces floating-point assembly programs from the specifiations of FIR, IIR, and adaptive transversal filters, then floating-point programs are transformed to fixed-point versions by the automatic scaling software.

• Journal of the Korea Society of Computer and Information
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• v.22 no.6
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• pp.95-100
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• 2017

Recently, as stress has become a major threat to people's health, there is a growing interest in wearable stress management services for stress relief. In this paper, we developed a wearable device(Care-on) capable of extracting changeable human voice information at each site and a Healthcare App(S-Manager) that enables stress management in real time using the wearable device. It collects and analyzes variable real-time voice information for each part of the person's body. And It also provides the ability to monitor stress conditions in a mobile environment and provide feedback on the analysis results in step by step in the mobile environment. We tested the developed wearable devices and app in a mobile environment and analyzed the results to confirm their usefulness.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.227-230
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• 1995

This paper presents continuous control concept of unsymmetrical 2 phase induction machine(I.M.). For 2 phase driving of the unsymmetrical I.M., variable voltage and variable frequency inverter is needed. In this paper, a new 12 step PWM 2 phase inverter was proposed. And then, proposed inverter fed 2 phase driving of unsymmetrical I.M. was studied, expecially on average torque and pulsation torque. This system has merits like higher fundamental component and better harmonic characteristics. The simulation was done on this issue and experimental research is on the way.