• Structural Engineering and Mechanics
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• 제66권6호
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• pp.737-748
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• 2018

The current study presents a new technique in the framework of the nonlocal elasticity theory for a comprehensive buckling analysis of Euler-Bernoulli nano-beams made up of bidirectional functionally graded material (BDFGM). The mechanical properties are considered by exponential and arbitrary variations for axial and transverse directions, respectively. The various circumstances including tapering, resting on two-parameter elastic foundation, step-wise or continuous variations of axial loading, various shapes of sections with various distribution laws of mechanical properties and various boundary conditions like the multi-span beams are taken into account. As far as we know, for the first time in the current work, the buckling analyses of BDFGM nano-beams are carried out under mentioned circumstances. The critical buckling loads and mode shapes are calculated by using energy method and a new technique based on calculus of variations and collocation method. Fast convergence and excellent agreement with the known data in literature, wherever possible, presents the efficiency of proposed technique. The effects of boundary conditions, material and taper constants, foundation moduli, variable axial compression and small-scale of nano-beam on the buckling loads and mode shapes are investigated. Moreover the analytical solutions, for the simpler cases are provided in appendices.

• 한국정보통신학회논문지
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• 제9권8호
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• pp.1774-1779
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• 2005

본 논문에서는 그래프 이론에 기초를 둔 GFDD를 사용하여 디지털논리시스템을 구성하는 한가지 방법을 제안하였다. 제안한 방법은 먼저 유한체와 그래프 이론의 수학적 성질을 논의하였으며, 단일변수에 대한 동작영역과 함수영역간의 변환을 용이하게 하기 위한 변환행렬 $\psi$GF(P)(1)과 $\xi$GF(P)(1)을 논의하였다. 그리고 디지털스위칭함수를 구하기 위한 Reed-Muller 확장을 논의하였으며, 이를 다변수인 경우로 확장하기 위해 Kronecker Product를 논의하였다.

• 한국재료학회지
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• 제21권7호
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• pp.377-383
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• 2011

Thermoelectric power, dc conductivity, and the dielectric relaxation properties of $La_2NiO_{4.03}$ are reported in the temperature range of 77 K - 300 K and in a frequency range of 20 Hz - 1 MHz. Thermoelectric power was positive below 300K. The measured thermoelectric power of $La_2NiO_{4.03}$ decreased linearly with temperature. The dc conductivity showed a temperature variation consistent with the variable range hopping mechanism at low temperatures and the adiabatic polaron hopping mechanism at high temperatures. The low temperature dc conductivity mechanism in $La_2NiO_{4.03}$ was analyzed using Mott's approach. The temperature dependence of thermoelectric power and dc conductivity suggests that the charge carriers responsible for conduction are strongly localized. The relaxation mechanism has been discussed in the frame of the electric modulus and loss spectra. The scaling behavior of the modulus and loss tangent suggests that the relaxation describes the same mechanism at various temperatures. The logarithmic angular frequency dependence of the loss peak is found to obey the Arrhenius law with activation energy of ~ 0.106eV. At low temperature, variable range hopping and large dielectric relaxation behavior for $La_2NiO_{4.03}$ are consistent with the polaronic nature of the charge carriers.

• 펄프종이기술
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• 제31권3호
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• pp.19-25
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• 1999

Effects of the process variable in Condebelt press drying including drying temperature, pressure , drying time, and moisture content of the sheets on the paper properties were examined. The experiment was performed with a static rig and Korean OCC was used as raw material. Significant improvement in sheet density, compression strength, tensile strength, surface smoothness ,etc. was obtained when condebelt drying was applied. Control of pressure and inlet dryness was found to be two most critical variables in improving sheet properties.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.211-216
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• 2003

Coated bars are protecting reinforcing bars from corrosion and enhancing durabilities of reinforced concrete structures are tested to evaluate corrosion protection properties. Tests are performed based on the relevant standards of ACI and ASTM, such as chemical resistance, salt water spray, salt crack test and chloride permeability test with the main variable of the coating thickness. Three type materials are tested by Polyethylene, epoxy and bare bar. Test results show good chemical protection property and chloride permeability. Polyethylene coated bar is good coating material than any other materials.

• Journal of the Korean Data and Information Science Society
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• 제20권4호
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• pp.741-747
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• 2009

Properties of multivariate Shewhart and EWMA (Exponentially Weighted Moving Average) control charts for monitoring variance-covariance matrix of quality variables are investigated. Performances of the proposed charts are evaluated for matched fixed sampling interval (FSI) and variable sampling interval (VSI) charts in terms of average time to signal (ATS) and average number of samples to signal (ANSS). Average number of swiches (ANSW) of the proposed VSI charts are also investigated.

• Journal of applied mathematics & informatics
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• 제38권1_2호
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• pp.145-157
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• 2020

In this article, we define a generating function of the generalized (p, q)-poly-Bernoulli polynomials with variable a by using the polylogarithm function. From the definition, we derive some properties that is concerned with other numbers and polynomials. Furthermore, we construct a special functions and give some symmetric identities involving the generalized (p, q)-poly-Bernoulli polynomials and power sums of the first integers.

• Communications for Statistical Applications and Methods
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• 제13권3호
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• pp.657-667
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• 2006

The concept of entropy, introduced in communication theory by Shannon (1948) as a measure of uncertainty, is of prime interest in information-theoretic statistics. This paper considers the minimum variance unbiased estimation for the maximum entropy of the transformed inverse Gaussian random variable by $Y=X^{-1/2}$. The properties of the derived UMVU estimator is investigated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.299-304
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• 1988

This paper describes the application of the variable structure control(VSC) concept for the position control of electro-hydraulic servomtor system. The basic philosopy of VSC is that the structure of the feedback control is altered as the state crosses discontinuity surfaces in the state surface with the result that certain desirable properties are achieved. The switching of the control function yields total(or selective) invariance to system parameter variations and disturbances, and closed loop eigen value placement in time-varing and uncertain systems.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.137-140
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• 2003

In this paper, we propose a new construction algorithm for the reversible variable-length code (RVLC) using a simplified average length function of the optimal Huffman code. RVLC is introduced as one of the error resilience tools in H.263+ and MPEG-4 owing to its error-correcting capability. The proposed algorithm demonstrates an improved performance in terms of the average codeword length over the existing HVLC algorithms.