• 전자공학회논문지A
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• 제31A권6호
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• pp.9-17
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• 1994

ATM (Asynchronous Transfer Mode) has a fixed-length packet transport scheme. It is one of the promising proposals in B-ISDN.Since the packet length is fixed, it can be potentially to perform the various service to users. In this paper, a queueing model for an ATM multip`exer loaded by CBR and ON/OFF input sources is considered, and the two-queue system which each type of input sources has a queue with a finite capacity is analyzed. The cell loss probabilities for a performance measures of ATM multiplexer are derived, and are also evaluated through numerical examples. As a result, the cell loss probability of ON/OFF sources for the queue size is rapidly decreased when the multiplexed number and burstiness are increased. Since cells of the CBR source have lower priority than cells of the ON/OFF source, cell loss probabilities of CBR sources are accordingly high independently of CBR cell arrival rate when the number of CBR sources is large.

• 산업공학
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• 제18권4호
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• pp.494-503
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• 2005

This paper considers the problem of performance analysis for the multiplexer, when homogeneous periodic on-off sources are statistically multiplexed. Periodic on-off source model is defined that on-period and off-period are repeated by once in a deterministic periodic time and in on-period, cell arrives with deterministic time interval. In order to reflect periodicity of source model, we consider two multiplexing situation, such as random multiplexing and synchronized multiplexing. In both case, we obtain the overload-period distribution in the multiplexer, and an approximate method using the overload period distribution is suggested for obtaining the CLP(Cell Loss Probability) in the buffer of the multiplexer. A numerical example using MPEG-I real traffic samples and the results are also presented.

• 한국통신학회논문지
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• 제24권10B호
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• pp.1861-1866
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• 1999

ISDN은 사용자에게 mB+1D의 channel을 제공한다. AO/DI기능은 D-channel을 통하여 저속의 지속적인 연결을 제공하며 고속의 통신이 필요한 경우에는 B-channel을 통하여 고속의 대역폭을 제공한다. 본 논문에서는 ISDN 환경에서의 다중 ON-OFF 소스에 대한 AO/DI기능의 성능분석을 수행한다. 다중 ON-OFF 소스가 하나의 mB+1D ISDN 링크를 통하여 연결되어 있는 상황을 가정한다. AO/DI 기능이 구현안된 경우 요구되는 대역폭은 모든 소스의 피크 대역폭의 합으로 주어지나 AO/DI 기능이 구현된 경우에는 실제로 사용되어지는 대역폭에 근접하게 대역폭이 할당된다.

• 산업공학
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• 제12권2호
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• pp.312-318
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• 1999

This paper considers the cell loss probability(CLP) in a multiplexer with the superposition of heterogeneous ON/OFF sources. The input traffic is composed of k classes. Traffic of class i is the superposition of M_(i) ON/OFF sources. Recently, the method based on the Markov modulated deterministic process(MMDP) is presented. Basically, it is the discretized model of stochastic fluid flow process(SFFP) and gives the CLP very fast, but under-estimates the CLP especially when the value of estimated CLP is very low. This paper develops the discretized model of Markov modulated Poisson process(MMPP). It is a special type of switched batch Bernoulli process(SBBP). Combining the transition probability matrix of MMDP and SBBP according to the state which is characterized by the arrival rate, this paper presents hybrid algorithm. The hybrid algorithm gives better estimate of CLP than that of MMDP and faster than SBBP.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1999년도 추계학술대회 및 정기총회 : 정보통신기술의 활용과 21세기 전자상거래
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• pp.23-23
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• 1999

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권6호
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• pp.223-227
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• 2005

Insulation failure of traction motor stator coil depends on the continuous stress imposed on it and knowing its insulation condition is an issue of significance for proper safety operation. In this paper, application of the NN (Neural Network) as a scheme of the off-line PD (partial discharge) diagnosis method that occurs at the stator coil of a traction motor was studied. For PD data acquisition, three defective models were made; internal void discharge model, slot discharge model and surface discharge model. PD data for recognition were acquired from a PD detector. Statistical distributions and parameters were calculated to perform recognition between model discharge sources. These statistical distribution parameters are applied to classify PD sources by the NN with a good recognition rate on the discharge sources.

• 대한산업공학회지
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• 제22권3호
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• pp.387-398
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• 1996

In this study the cell arrival processes from pre-buffer into multiplexer for MPEG(Motion Picture Experts Group) coding video sources are analyzed with consideration of the traffic periodicity in frame level. The analysis is performed by introducing the two arrival models, that is, periodic on/off source model and periodic uniform arrival model. Modulated $N^*D$/D/1 queueing system is utilized in periodic on/off source model, while ${\Sigma}{N_i}^*D_i$/D/1 queueing system is used in periodic uniform arrival model. The presented models are validated by comparing with computer simulations. Numerical results for periodic uniform arrival model are shown to be very accurate, but those of periodic on/off source model are shown to be inaccurate as the number of sources are increased.

• 한국소음진동공학회논문집
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• 제25권8호
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• pp.539-545
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• 2015

Intense acoustic load is generated when a launch vehicle lifts off, causing the damaging vibrations at the launch vehicle or satellite within the fairing. This paper is concerned with the prediction of lift-off acoustic loads for a launch vehicle. As a test example, the lift-off acoustic load on the Korean launch vehicle, NARO, is predicted by the existing calculation tool, the modified Eldred's second method. Although the acoustic sources, assumed as point sources, are to be located along the center line of the exhaust plume when using the Eldred's prediction method, the exact location of the deflected center line of exhaust gas flow is not usually known. To search for the most appropriate source positions, six models of source line distribution are suggested and the acoustic load prediction results from these models are compared with the actual measurements. It is found that the predicted sound pressure spectrum of the Naro is the most similar to the measured data when the centerline of the turbulent kinetic energy contour is used as the source line.

• 한국통신학회논문지
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• 제18권6호
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• pp.889-894
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• 1993

ATM은 음성, 비데오, 벌크 데이타등과 같은 다양한 형태의 버스트 트래픽을 수용할 수 있다. ATM망에서 트래픽 소오스를 효과적으로 처리하거나 가능한한 대역폭 사용율을 증가시키기 위해서는 통계적 다중화 구조가 채택되어야 한다. 본 논문은 독립적인 입력 소오스를 갖고 유한개의 버퍼 크기를 갖는 큐잉 시스템에서 큐 상태분포를 계산하기 위한 효과적인 계산 절차를 논의하고, 이러한 반복적인 계산방법을 통해 셀 손실율을 정확하게 계산한다. 또한 동질의 ON-OFF 소오스를 갖는 ATM 다중화기에 대해 몇가지의 수치계산 예를 통해 셀 손실율의 특성을 조사해 본다.

• 한국전기전자재료학회논문지
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• 제18권8호
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• pp.766-771
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• 2005

In this study, PD(partial discharge) signals which occur at stator coil of traction Motor are acquired these data are used for classifying the PD sources. NN(neural network) has recently applied to classify the PD pattern. The PD data are used for the learning process to classify PD sources. The PD data come from normal specimen and defective specimens such as internal void discharges, slot discharges and surface discharges. PD distribution parameters are calculated from a set of the data, which is used to realize diagnostic algorithm. NN which applies distribution parameters is useful to classify the PD patterns of defective sources generating in stator coil of traction motor.