• Management Science and Financial Engineering
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• 제4권2호
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• pp.43-58
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• 1998

Packet switch is a key component in high speed digital networks. This paper investigates congestion phenomena in the packet switching with input buffers. For large value of switch size N, mathematical models have been developed to analyze asymptotic maximum switch throughput under nonuniform traffic. Simulation study has also been done for small values of finite N. The rapid convergence of the switch performance with finite switch size to asymptotic solutions implies that asymptotic analytical solutions approximate very closely to maximum throughputs for reasonably large but finite N. Numerical examples show that non-uniformity in traffic pattern could result in serious degradation in packet switch performance, while the maximum switch throughput is 0.586 when the traffic load is uniform over the output trunks. Window scheduling policy seems to work only when the traffic is relatively uniformly distributed. As traffic non-uniformity increases, the effect of window size on throughput is getting mediocre.

• 전기학회논문지
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• 제65권12호
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• pp.2177-2182
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• 2016

Using the existing exact but quite complicated symbol error rate (SER) expressions for M-ary phase shift keying (M-PSK) and M-ary differential phase shift keying (M-DPSK), we derive effective and concise closed-form asymptotic SER formulas especially in Rician-Nakagami fading channels. The derived formulas can be utilized to efficiently verify the achievable error rate performances of M-PSK and M-DPSK systems for the Rician-Nakagami fading environments. In addition, by exploiting the modulation gains directly obtained from the asymptotic SER formulas, we also theoretically demonstrate that M-DPSK suffers an asymptotic SER performance loss of 3.01dB with respect to M-PSK for a given M in Rician-Nakagami fading channels at high signal-to-noise ratio (SNR).

• Journal of the Korean Statistical Society
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• 제28권1호
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• pp.57-72
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• 1999

Falk(1994) showed that the asymptotic efficiency of the Pickands estimator of the extreme value index $\beta$ can considerably be improved by a simple convex combination. In this paper we propose an alternative estimator of $\beta$ which is as asymptotically efficient as the optimal convex combination of the Pickands estimators but has a better finite-sample performance. We prove consistency and asymptotic normality of the proposed estimator. Monte Carlo simulations are conducted to compare the finite-sample performances of the proposed estimator and the optimal convex combination estimator.

• Journal of the Korean Statistical Society
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• 제34권2호
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• pp.99-107
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• 2005

In this paper we consider the asymptotic mean squared error of positive part James-Stein estimators. In the normal-normal example, estimators of the mean squared error of these estimators are provided which are correct asymptotically up to O($m^{-l}$). Asymptotic estimators of the MSE's which correct up to O($m^{-l}$) are also provide. Here, m denotes the number of strata. A simulation study is undertaken to evaluate the performance of these estimators.

• Journal of Communications and Networks
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• 제5권2호
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• pp.96-103
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• 2003

Asymptotic theorems are very commonly used in probability. For systems whose performance depends on a set of n random parameters, asymptotic analyses for n${\to}{\infty}$ are often used to simplify calculations and obtain results yielding useful hints at the behavior of the system for finite n. These asymptotic analyses are especially useful whenever the convergence to the asymptotic results is so fast that even for moderate n they yield results close to the true values. This tutorial paper illustrates this principle by applying it to capacity calculations of multiple-antenna systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.37-42
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• 1992

The main purpose of the paper is to derive asymptotic formulae for performance characteristics(throughput, delay) of large-scale token-passing network with buffered stations and to optimize the buffer capacity with respect to the probability of data generation. We consider two versions of token-passing network: uniform and nonuniform token-passing time interval. All results obtained are supported by simulations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.519-522
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• 1990

This paper formulates a problem of analysis and design of serial production lines, closed with respect to the number of carriers available in the system for parts transportation between operations. For two machines - two buffers systems, the paper gives an asymptotic solution and shows that optimization of the system with respect to the number of carriers available and the capacity of the feedback buffer may lead to substantial improvements of system's performance.

• Smart Structures and Systems
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• 제2권4호
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• pp.313-320
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• 2006

The reliability analysis of structures subjected to stochastic loading involves evaluation of time and probability of the system's residence in a reference domain. In this paper, we derive an asymptotic estimate of exit time for multi-degrees-of-freedom structural systems. The system's dynamics is governed by the Lagrangian equations with linear dissipation and fast additive noise. The logarithmic asymptotic of exit time is found explicitly as a sum of two terms dependent on kinetic and potential energy of the system, respectively. As an example, we estimate exit time and an associated structural performance for a rocking structure.

• 제어로봇시스템학회논문지
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• 제10권1호
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• pp.15-21
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• 2004

This paper deals with asymptotic stabilization problems for linear systems with time-varying input disturbances. In order to eliminate the influence of a disturbance on the system, a disturbance observer is designed and the time-varying disturbance can be rejected using its estimated value. Since the disturbance observer is kind of low-pass filter, it has inevitably estimation errors. To eliminate the inflences on the performance due to these errors, the additional control is designed based on these estimation errors using a well-known min-max control method. It is shown that the asymptotic stability of the closed-loop system is guaranteed. In general, the min-max control method requires the switching of control inputs and the switching magnitude of the control input is determined by the disturbance estimation error bounds. As the error bounds can be made arbitrarily small by choosing the high gain for the disturbance observer, the control method suggested in this paper can reduce the chattering phenomena as small as possible. Therefore, it has superior performance to the existing ones.

• 한국통신학회논문지
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• 제23권6호
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• pp.1454-1460
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• 1998

이 논문에서는 중앙값을 움직인 부호를 바탕으로 한 검파기를 제안하고 그 점근 성능과 우한 표본 성능을 살펴본다. 이 검파기를 중앙값을 움직인 부호 검파기라 부르는데, 이는 고전적인 부호 검파기를 확장한 것이다. 먼저, 점근 최적 이동 중앙값들과 그들의 특성을 알아보고, 이 검파기의 점근 상대효율을 생각해 본다. 확률밀도함수를 알고 있는 잡음환경에서 알려진 신호를 검파하는 문제와 분포를 거의 알 수 없는 잡음에서 알려진 신호를 검파하는 문제를 다룬다.