• Communications for Statistical Applications and Methods
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• v.21 no.3
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• pp.201-212
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• 2014

We provide a simple basic method to find bounds for higher order moments of unimodal distributions in terms of lower order moments when the random variable takes value in a given finite real interval. The bounds for moments in terms of the geometric mean of the distribution are also derived. Both continuous and discrete cases are considered. The bounds for the ratio and difference of moments are obtained. The special cases provide refinements of several well-known inequalities, such as Kantorovich inequality and Krasnosel'skii and Krein inequality.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.3
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• pp.171-180
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• 1992

This paper proposes a solution approach to linear problems with many constraints of variable upper bound (VUB) type. This type of constraints are commonly found in various scheduling type problems for which tighter bounds are essential to achieve an efficiency in enumeration. An analytical framework based on factorization is adopted to devise a solution approach to the problem and extend it for more generalized VUB problem (GVUB). This research shows why the VUB type constraints are amenable to the factorization and gives a unified approach to generalized upper bound(GUB) problems, VUB problems and GVUB problems. Implementation issues are also included.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11C
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• pp.907-910
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• 2010

This paper presents the design of block lengths for irregular low-density parity-check (LDPC) codes based on the maximum variable degree $d_{{\upsilon},max}$. To design a block length, the performance degradation of belief-propagation (BP) decoding performance from upper bounds on the maximum likelihood (ML) decoding performance is used as an important factor. Since for large block lengths, the performance of irregular LDPC codes is very close to the Shannon limit, we focus on moderate block lengths ($5{\times}10^2\;{\leq}\;N\;{\leq}\;4{\times}10^3$). Given degree distributions, the purpose of our paper is to find proper block lengths based on the maximum variable degree $d_{{\upsilon},max}$. We also present some simulation results which show how a block length can be optimized.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.52-54
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• 1996

A number of algorithm using the VSS(Variable Structure System) for uncertain dynamic system are developed. But, in these algorithms, the assumption that the uncertainties are bounded and their bounds are available to the designer is involved. And bounds on the uncertainties are an important clue to guarantee the stability of the closed loop system. However, sometimes bounds on the uncertainties may not be easily obtained because of the complexity of the structure of the uncertainties. Therefore, a methodology by which the boundary values on the uncertainties can be easily obtained is required. The VSS proposed in this proposal employ the new adaptive VSS scheme for uncertain dynamic system being estimated on line. The resulting control law is simple and easy to apply to on line computer control. It can also suppress chattering and maintain good tracking precision even if unmodeled dynamics are considered. And, a new method using nonlinear switching surface is introduced so that the speed response is improved and the good transient response can be obtained. Simulation results are presented and show the advantage of the proposed adaptive VSS with nonlinear switching surfaces.

• Journal of the Korean Institute of Intelligent Systems
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• v.11 no.9
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• pp.788-792
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• 2001

Although the general sliding model control has the robust property, bounds on the disturbances and parameter variations should be known a prior to the designer of the control system. However, these bounds may not be easily obtained. Fuzzy logic provides an effective way to design a controller of the system with disturbances and parameter variations. Therefore, combination of the best feature of the fuzzy logic control and the sliding mode control is considered. In this paper, the adaptive fuzzy variable structure controller developed for variables of fuzzy logic. A variable length pendulum system is used to demonstrate the availability of the proposed algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.797-808
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• 2000

This paper presents the bit error rate(BER) upper bounds for trellis coded asymmetric 8PSK(TC-A8PSK) system using the Ka-band satellite in the rain fading environment. The probability density function(PDF) for the rain fading random variable can be theoretically derived by assuming that the rain attenuation can be approximated to a long-normal distribution and the rain fading parameters are calculated by using the rain precipitation data from the Crane global model. Furthermore, we analyze the BER upper bounds of TC-A8PSK system according to the number of states in the trellis diagram and the availability of channel state information(CSI). In the past, Divsalar and Simon[9] has analyzed the BER upper bounds of 2-state TCM system in Rician fading channels however this paper is the first to analyze the BER upper bounds of TCM system in the rain fading channels. Finally, we summarize the dominant six factors which are closely related to the BER upper bounds of TC-A8PSK satellite system in the rain fading channel as follows: 1) frequency band, 2) rain intensity, 3) elevation angle, 4) signal to noise ratio, 5) asymmetric angle, and 6) availability of CSI.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1133-1138
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• 1991

A control of nonlinear system is motivated by the fact that all real plants are nonlinear systems and model identification introduces parameter errors. The purpose of this study is to design a Discrete Variable Structure Controller(DVSC) for single-rod hydraulic cylinder system. The model contains uncertain parameters which we known to lie upper and lower bounds. In the design of DVSC, the boundary layer concept was adopted to reduce cattering. The DVSC was evaluated through digital computer simulation and compared with a VSC (analog controller).

• Korean Journal of Mathematics
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• v.30 no.3
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• pp.503-512
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• 2022

In this paper, we are concerned with the problem of locating the zeros of regular polynomials of a quaternionic variable with quaternionic coefficients. We derive new bounds of Eneström-Kakeya type for the zeros of these polynomials by virtue of a maximum modulus theorem and the structure of the zero sets in the newly developed theory of regular functions and polynomials of a quaternionic variable. Our results generalize some recently proved results about the distribution of zeros of a quaternionic polynomial.

• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.449-472
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• 2001

A variety bounds are obtained for the variance and expectation of a continuous random variable whose p.d.f. is defined over a finite interval. Previous results are shown to be particular cases of the current more general development.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1992.04b
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• pp.14-23
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• 1992

본 논문은 스케줄링 문제등 정수계획문제에서 흔히 찾아볼 수 있는 변수상한 제약을 갖는 문제의 효율적인 해법을 위한 분석적인 틀을 마련하기 위한 연구이다. 본 연구에서는 이 문제에 관한 기존의 알고리즘적 해법과 달리 분해기법을 이용하여 일반변수상한 문제에 까지 확장 적용될 수 있음을 분석적으로 보였다.