• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.938-947
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• 2003

In this paper, we derived the formula for estimating the power of the electric motors needed to operate the Decanter-type centrifuge. In the derivation of the formula the sludge-removal torque is to be supplied from the formula derived in the first paper. The intricate nature of the transmission mechanism in the planetary gear trains of the sludge-removal power and torque has been clarified in this second paper. In particular we considered two-motor system, where the main motor drives the machine while the differential-speed control motor plays the role of braking in adjusting the differential speed. Sample calculation for the specific design treated in the first paper showed that the selection criterion for the main motor depends on the lower limit of the differential speed; when the lower limit is set low, it should be selected based on the steadily operating power, while it should be selected based on the starting power when the lower limit is set high. The total power required by both the main motor and the differential-speed control motor increases as the differential speed is decreased. It is suggested that the power loss in the differential-speed control motor could be minimized by attaching an electric generator to it.

• Journal of Educational Research in Mathematics
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• v.8 no.2
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• pp.495-507
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• 1998

This article intends to review what problems the terms in calculus have and how those problems are caused. For this purpose We make examinations on the considerations in the analysis of mathematical terminology, which includes the problems of general and technical terms, the meaning and the boundary of words, their consistency, the name and meaning, concept and their concept images, translations and qwerty effects. And in chapter 3, We analyse the textbook which are currently used, through which I was able to find out that the terms in calculus have some problems, In other words, the key terms such as "differentiable", "differential coefficient", "differential" have their roots in the term "differential" but the term "derived function" is very distinct from other terms and thus obstructs the consistency of terms. And the central term "differential" is being used without clear definition. In particular, the fact that "differential", when used in its arbitrary definition, has the image of "splitting minutely" can be an obstacle to understanding the exact concepts of calculus. In chapter 4, We make a review on the history of calculus and the term "differential" currently used in modern mathematics so that I can identify the origin of the problem connected with the usage of the term "differential". We should recognize the specified problems and its causes and keep their instructional implications in mind. Furthermore, following researches and discussions should be made on whether the terminology system of calculus should be reestablished and how the reestablishment should be made.e terminology system of calculus should be reestablished and how the reestablishment should be made.

• Communications of the Korean Mathematical Society
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• v.26 no.4
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• pp.709-720
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• 2011

We obtain special type of differential equations which their solution are random variable with known continuous density function. Stochastic differential equations (SDE) of continuous distributions are determined by the Fokker-Planck theorem. We approximate solution of differential equation with numerical methods such as: the Euler-Maruyama and ten stages explicit Runge-Kutta method, and analysis error prediction statistically. Numerical results, show the performance of the Rung-Kutta method with respect to the Euler-Maruyama. The exponential two parameters, exponential, normal, uniform, beta, gamma and Parreto distributions are considered in this paper.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.387-395
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• 1991

Large deflection behavior of cylindrically orthotropic thin circular plates is investigated by the numerical technique of differential quadrature. Governing equations are derived in terms of transverse deflection and stress function and a Newton-Raphson technique is used to solve the nonlinear systems of equations. For small values of degree of differential quadrature (N.leq.13), as the degree of differential quadrature increases, the center deflection converges. However, as N increases further, the center deflection diverges by ill-conditioning in the weighting coefficients. As the orthotropic parameter increases, the center deflection decreases and behaves linear for the loads. At center, the stress is affected mainly by orthotropic parameter, while the stress is affected mainly by boundary condition at edge.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.73-82
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• 2017

Vertical shortening in tall buildings would be of little concern if all vertical elements shortened evenly. However, vertical elements such as walls and columns may shorten different amounts due to different service axial stress levels. With height, the differential shortening may become significant and impact the strength design and serviceability of the building. Sometimes column transfers or other vertical structural irregularities may cause differential shortening. If differential shortening is not addressed properly, it can impact the serviceability of the building. This paper takes the perspective of a structural engineer in planning the design, predicting the shortening and its effects, and communicating the information to the contractor.

• Structural Engineering and Mechanics
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• v.52 no.5
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• pp.971-995
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• 2014

The parts of semi-rigid connected and partially embedded piles in elastic soil, above the soil and embedded in the soil are called the first region and second region, respectively. The upper end of the pile in the first region is supported by linear-elastic rotational spring. The forth order differential equations of both region for critical buckling load of partially embedded and semi-rigid connected pile with shear deformation are established using small-displacement theory and Winkler hypothesis. These differential equations are solved by differential transform method (DTM) and analytical method and critical buckling loads of semirigid connected and partially embedded pile are obtained, results are given in tables and graphs are presented for investigating the effects of relative stiffness of the pile and flexibility of rotational spring.

• Structural Engineering and Mechanics
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• v.24 no.2
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• pp.247-268
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• 2006

The parts of pile, above the soil and embedded in the soil are called the first region and second region, respectively. The forth order differential equations of both region for critical buckling load of partially embedded pile with shear deformation are obtained using the small-displacement theory and Winkler hypothesis. It is assumed that the behavior of material of the pile is linear-elastic and that axial force along the pile length and modulus of subgrade reaction for the second region to be constant. Shear effect is included in the differential equations by considering shear deformation in the second derivative of the elastic curve function. Critical buckling loads of the pile are calculated for by differential transform method (DTM) and analytical method, results are given in tables and variation of critical buckling loads corresponding to relative stiffness of the pile are presented in graphs.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.155-158
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• 2008

In 1989, Kocher et al. introduced Differential Power Attack on block ciphers. This attack allows to extract secret key used in cryptographic computations even if these are executed inside tamper-resistant devices such as smart card. Since 1989, many papers were published to improve resistance of DPA. At FSE 2003 and 2004, Akkar and Goubin presented several masking methods to protect iterated block ciphers such as DES against Differential Power Attack. The idea is to randomize the first few and last few rounds(3 $\sim$ 4 round) of the cipher with independent random masks at each round and thereby disabling power attacks on subsequent inner rounds. This paper show how to combine truncated differential cryptanalysis applied to the first few rounds of the cipher with power attacks to extract the secret key from intermediate unmasked values.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.6
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• pp.2005-2013
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• 1996

Particle paths and flow fields in a prototype differential mobility analyzer (DMA) were numerically analyzed solving Navier-Stokes equation, electric field equation and particle motion considering viscous drag force, Coulomb force and polarization force. Analytically predicted particle diameters for the prototype DMA are in good agreement with the measured particle diameters within $\pm$1%. And the analytically predicted particle diameters are also in good agreement with numerical results for the prototype DMA.

• Nonlinear Functional Analysis and Applications
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• v.29 no.2
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• pp.527-543
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• 2024

In the realm of differential games and bioeconomic modeling, where intricate systems and multifaceted interactions abound, we explore the precision and efficiency of the Chebyshev Tau method (CTM). We begin with the Weierstrass Approximation Theorem, employing Chebyshev polynomials to pave the way for solving intricate bioeconomic differential games. Our case study revolves around a three-player bioeconomic differential game, unveiling a unique open-loop Nash equilibrium using Hamiltonians and the FilippovCesari existence theorem. We then transition to numerical implementation, employing CTM to resolve a Three-Point Boundary Value Problem (TPBVP) with varying degrees of approximation.