• Journal of Korean Institute of Industrial Engineers
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• v.23 no.1
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• pp.235-247
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• 1997

In this study, the performance of ATM multiplexer with MPEG(Motion Pictures Experts Group) video is analyzed by considering the effect of the MPEG GOP(Group of Pictures) structure. By assuming that frame starting times are synchronized, aggregated traffics are considered to be transmitted at the beginning of each frame time units. The aggregated number of cells generated during a frame time unit is, therefore, derived from distributions of individual sources. The stationary probability of buffer occupancy can be easily obtained by using a property of the periodicity of aggregated traffics. Simulation approach is also used to determine the traffic load for a given probability of satisfying QoS(Quality of Service).

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.217-230
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• 2017

In this paper we deal with the difference equation $$y_{n+1}=\frac{ay_{n-1}}{by_ny_{n-1}+cy_{n-1}y_{n-2}+d}$$, $$n{\in}\mathbb{N}_0$$, where the coefficients a, b, c, d are positive real numbers and the initial conditions $y_{-2}$, $y_{-1}$, $y_0$ are nonnegative real numbers. Here, we investigate global asymptotic stability, periodicity, boundedness and oscillation of positive solutions of the above equation.

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.267-276
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• 2017

The purpose of this paper is to investigate the local asymptotic stability of equilibria, the periodic nature of solutions, the existence of unbounded solutions and the global behavior of solutions of the fractional difference equation $$x_{n+1}=\frac{^{{\alpha}x}n-1(k+1)}{{\beta}+{\gamma}x^p_{n-k}x^q_{n-(k+2)}}$$, $$n=0,1,{\dots}$$ where the parameters ${\alpha}$, ${\beta}$, ${\gamma}$, p, q are non-negative numbers and the initial values $x_{-(k+2)}$,$x_{-(k+1)}$, ${\dots}$, $x_{-1}$, $x_0{\in}\mathb{R}^+$.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.529-532
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• 2002

This research treated development of real time pitch tracer for training of musical tune of speech signal and pre-processing and post-processing technics were proposed to get higher accuracy in extraction of pitch. Autocorrelation Function was used to get pitch frequency from 64Hz to 980Hz in real time. Half Rectifier method and Envelop extraction method as a pre-processing was used to get higher accuracy in pitch detection, and improved results were obtained on noised speech signal. Post-processing method using periodicity of Autocorrelation was proposed to get higher accuracy in the high frequency region.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.884-890
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• 1996

We have investigated a structural change of Si(100)-($2 \times 1$)-Sb surface caused by atomic hydrogen adsorption at room temperature using time-of-flight impact collision ion scattering spectroscopy (TOF-ICISS) and low energy electron diffraction (LEED). We found that when atomic hydrogen adsorbs on the Si(100)-($2 \times 1$)-Sb surface, (1) the partial desorption of Sb atoms from the Si(100) surface occurs even at room temperature, (2) the rest Sb atoms are displaced from their original positions and form an almost two-dimensional layer with dispersive distribution of Sb atoms, and (3) the structural transformation into the Si(100)-($1 \times 1$)-H periodicity is induced by the formation of the $1 \times 1$-H dihydride phase on the Si substrate.

• Journal of Astronomy and Space Sciences
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• v.2 no.2
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• pp.69-99
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• 1985

The UBV observations of the Brightest RS CVn-type eclipsing binary star AR Lac were made at four observatories, two in Korean and two in the U.S. in the 1980-81 and 1981-82 seasons. As a result of the cooperation, two light curves in the yellow and in the blue were completed for each observing seasons. Ultraviolet observations were also made at three of the four observatories. The orbital period of AR Lac apparantly decreased around 1977. An analysis of our yellow light curves together with five other yellow curves available in the literature since 1975 shows that there seems no periodicity in the migration of the distortion waves. There is a gradual decrease of at least 0.m1 between 1976 and 1982 in the brightness of the cooler component if one assumes that the hotter component is constant.

• Journal of Astronomy and Space Sciences
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• v.3 no.1
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• pp.15-27
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• 1986

Variation of radius vector was computed by Cowell's method. Perturbations due to the Sun, moon, and earth's asymmetrical potential are considered. We summarize our results as follows : I) $J_2$ term does not affect the equatorial orbit. ii) Large perturbation and secular variation on the above orbit are caused by tesseral harmonics. iii) The other perturbations have small effect and periodicity.

• The Korean Journal of Applied Statistics
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• v.5 no.1
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• pp.59-80
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• 1992

This paper is concerned with the development and application of a stochastic model for winter air-temperature of Seoul area. The annual and interannual flucturations of the regression trend, periodicity and dependence of the air-temperature are analyzed based on the data during the past 30 years(1959-1989). A statistical procedure for using the stochastic model to predict the air-temperature is proposed. Some statistical characteristics of winter air-temperature including unusual air-temperature and Samhansaon are also discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.361-364
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• 2011

In this paper, This work demonstrates a experimental evaluation for vehicle road noise NVH performance from the component-level NVH measurements of Tire. The power unit noise from tire emitted by cars has been reduced. It has been found that tire noise dominates noise produced by the power train when vehicles are driven at high constant speed. Therefore tire pattern noise is affected by pattern and vehicle and transmission loss. Tire noise mechanism is generated by several mechanisms. The sound of tire can propagate either through the air or through the structure of vehicle. Pattern noise is the result of pressure variations through the air to the interior side of vehicle. Especially, smooth asphalt, the periodicity of tread design, groove depth is important factor, which have an influence on the reduction of tire pattern noise.

• Journal of KSNVE
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• v.10 no.6
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• pp.985-990
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• 2000

The signals that can be obtained from rotating machines often convey the information of machine. For example, if the machine under investigation has faults, then these signals often have pulse signals, embedded in noise. Therefore the ability to detect the fault signal in noise is major concern of fault diagnosis of rotating machine, In this paper, minimum variance cepstrum (MV cepstrum) . which can easily detect impulse in noise, has been applied to detect the type of faults of ball bearing system. To test the performance of this technique. various experiments have been performed for ball bearing elements that have man made faults. Results show that minimum variance cepstrum can easily detect the periodicity due to faults and also shows the pattern of excitation by the faults.