• Title, Summary, Keyword: various function

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Non-Equilibrium Green Function Method in Spin Transfer Torque

  • You, Chun-Yeol
    • Journal of Magnetics
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    • v.12 no.2
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    • pp.72-76
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    • 2007
  • We investigate the spin transfer torque in metallic multilayer system by employing Keldysh non-equilibrium Green function method. We study the dependences of the spin transfer torque on the detailed energy configuration of ferromagnetic, spacer, and lead layers. With Keldysh non-equilibrium Green function method applied to a single band model, we explore spin transfer torque effect in various layer structures and for various material parameters.

Brightness Function on TV Viewing Condition (TV 시청 조건에서의 Brightness Function)

  • 최성호;김희철;장수욱;김은수;한찬호;송규익
    • Proceedings of the IEEK Conference
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    • pp.2403-2406
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    • 2003
  • When viewing images, the relative luminance of the surround has a profound impact on the apparent contrast of the image. The dark surround causes the image elements to appear lighter than those viewed in an illuminated surround. For this reason, it is worthwhile to briefly review the general results of brightness sealing under a various viewing condition. Two of the most often cited parers on the topic of brightness scaling are Stevens-stevens and Bartleson-Breneman's function. There are, however, significant differences between the perceptual functions for simple-field and complex-field viewing. In this paper, we research the relationship between Steven's power law and Bartleson-Breneman's function. We present an appropriate brightness perception function due to TV system viewing conditions. Highlight luminance peak and absolute brightness threshold value in various adaptation levels are obtained from the proposed brightness function . Also, the luminance value of black level to produce the same contrast ratio with variety of display highlight luminance peak is obtained from the proposed brightness function.

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Extraction of Shape Information of Cost Function Using Dynamic Encoding Algorithm for Searches(DEAS) (최적화기법인 DEAS를 이용한 비용함수의 형상정보 추출)

  • Kim, Jong-Wook;Park, Young-Su;Kim, Tae-Gyu;Kim, Sang-Woo
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.8
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    • pp.790-797
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    • 2007
  • This paper proposes a new measure of cost function ruggedness in local optimization with DEAS. DEAS is a computational optimization method developed since 2002 and has been applied to various engineering fields with success. Since DEAS is a recent optimization method which is rarely introduced in Korean, this paper first provides a brief overview and description of DEAS. In minimizing cost function with this non-gradient method, information on function shape measured automatically will enhance search capability. Considering the search strategies of DEAS are well designed with binary matrix structures, analysis of search behaviors will produce beneficial shape information. This paper deals with a simple quadratic function contained with various magnitudes of noise, and DEAS finds local minimum yielding ruggedness measure of given cost function. The proposed shape information will be directly used in improving DEAS performance in future work.

Effects of Fuel Composition on Flame Transfer Function in Lean Premixed Combustor (희박 예혼합 연소기에서 연료 조성이 화염전달함수 특성에 미치는 영향)

  • Kim, Jinah;Kim, Jihwan;Lee, Jeongwon;Kim, Daesik
    • Journal of ILASS-Korea
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    • v.20 no.3
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    • pp.135-140
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    • 2015
  • Flame transfer function is used to determine the relationship between flow fluctuations and heat release perturbations in a lean premixed gas turbine combustor. The characteristics of flame transfer function are known to depend greatly on flame geometries in addition to other various flow conditions. However, it is not easy to experimentally measure the flame transfer function under various actual combustor operating conditions in terms of time and cost. The current research tries to model the flame transfer function using CFD(Computational Fluid Dynamics). From the results, it is shown that the calculated steady flame geometry can be exactly captured with consideration of the wall heat transfer and radiations. Also, unsteady analysis results show the close characteristics of the flame transfer function to the measured one in both gain and phase.

A Study on Deriving The Diversion Curve of I.C.s (I. C. 유형별 전환곡선식의 도출에 관한 연구)

  • 손진현;이용재
    • Journal of Korean Society of Transportation
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    • v.8 no.2
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    • pp.77-97
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    • 1990
  • Compared to modal split, the methods of forecasting traffic volumes diverted in various types of I.C.s have not been sufficiently studied. The purpose of this study is to derive a new diversion function that can represent the directional traffic volume in accordance with various geometrics of I.C.s. In general, knowing various traffic impedances and the amount of traffic production and attraction, one can estimate proper traffic volumes associated with directions by using a well-defined diversion function. This function is usually made by a series of process such as surveying directional traffic volumes on several I.C.s, analyzing with a regression method and verifying those results by statistical approaches. The function has been developed by rigorous statistical testings, mainly a regression analysis. This paper presents an effective method in planning and designing new roads, I.C.s and route choice of subway. Finally, some comparisons and improvements and suggested when one uses different types of relevant models and functions.

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Development of Algorithms for Sorting Peeled Garlic Using Machnie Vison (I) - Comparison of sorting accuracy between Bayes discriminant function and neural network - (기계시각을 이용한 박피 마늘 선별 알고리즘 개발 (I) - 베이즈 판별함수와 신경회로망에 의한 설별 정확도 비교 -)

  • 이상엽;이수희;노상하;배영환
    • Journal of Biosystems Engineering
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    • v.24 no.4
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    • pp.325-334
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    • 1999
  • The aim of this study was to present a groundwork for development of a sorting system of peeled garlics using machine vision. Images of various garlic samples such as sound, partially defective, discolored, rotten and un-peeled were obtained with a B/W machine vision system. Sorting factors which were based on normalized histogram and statistical analysis(STEPDISC Method) had good separability for various garlic samples. Bayes discriminant function and neural network sorting algorithms were developed with the sample images and were experimented on various garlic samples. It was showed that garlic samples could be classified by sorting algorithm with average sorting accuracies of 88.4% by Bayes discriminant function and 93.2% by neural network.

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An Accurate and Efficient Method of the Spray Paint Simulation for Robot OLP (로봇 Off-Line Programming을 위한 페인트 스프레이 시뮬레이션 방법론 개발)

  • Lee, Seung-Chan;Song, In-Ho;Borm, Jin-Hwan
    • Korean Journal of Computational Design and Engineering
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    • v.13 no.4
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    • pp.296-304
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    • 2008
  • Recently, various attempts are being done to apply off-line programming system to field of paint robot. But most commercial simulation softwares have problems that are slow simulation speed and not support various painting paramenters on simulation. This paper proposes enhanced paint simulation method for off-line programming system. For these, this method used the mathematical model of flux field from a previous research. The flux field has the flux distribution function, which reflects on the feature of paint spray. A previous research derived this flux distribution function for an integral function and calculated paint thickness function for an integral function. But if flux distribution function is defined as an integral function, it is inadequate to use for real-time simulation because a number of calculation is needed for estimation of paint thickness distribution. Therefore, we defined the flux distribution function by numerical method for reducing a mount of calculation for estimation of paint thickness. We derived the equation of paint thickness function analytically for reducing a mount of calculation from the paint distribution function defined by numerical method. In order to prove proposed paint simulation method this paper compares the simulated and measured thickness. From this comparison this paper show that paint thickness distribution is predicted precisely by proposed spray paint simulation process.

SOME τ-EXTENSIONS OF LAURICELLA FUNCTIONS OF SEVERAL VARIABLES

  • KALLA, SHYAM LAL;PARMAR, RAKESH KUMAR;PUROHIT, SUNIL DUTT
    • Communications of the Korean Mathematical Society
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    • v.30 no.3
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    • pp.239-252
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    • 2015
  • Motivated mainly by certain interesting extensions of the ${\tau}$-hypergeometric function defined by Virchenko et al. [11] and some ${\tau}$-Appell's function introduced by Al-Shammery and Kalla [1], we introduce here the ${\tau}$-Lauricella functions $F_A^{(n),{\tau}_1,{\cdots},{\tau}_n}$, $F_B^{(n),{\tau}_1,{\cdots},{\tau}_n}$ and $F_D^{(n),{\tau}_1,{\cdots},{\tau}_n}$ and the confluent forms ${\Phi}_2^{(n),{\tau}_1,{\cdots},{\tau}_n}$ and ${\Phi}_D^{(n),{\tau}_1,{\cdots},{\tau}_n}$ of n variables. We then systematically investigate their various integral representations of each of these ${\tau}$-Lauricella functions including their generating functions. Various (known or new) special cases and consequences of the results presented here are also considered.

SOME IDENTITIES INVOLVING THE LEGENDRE'S CHI-FUNCTION

  • Choi, June-Sang
    • Communications of the Korean Mathematical Society
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    • v.22 no.2
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    • pp.219-225
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    • 2007
  • Since the time of Euler, the dilogarithm and polylogarithm functions have been studied by many mathematicians who used various notations for the dilogarithm function $Li_2(z)$. These functions are related to many other mathematical functions and have a variety of application. The main objective of this paper is to present corrected versions of two equivalent factorization formulas involving the Legendre's Chi-function $\chi_2$ and an evaluation of a class of integrals which is useful to evaluate some integrals associated with the dilogarithm function.

The study of Method for the Diagnosis of Transformers Trouble

  • Song, Jae-Tae;Jeong, Seung-Cheol;Choi, Hyun-Seob;Park, Poo-Gyeon
    • 제어로봇시스템학회:학술대회논문집
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    • pp.118.1-118
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    • 2001
  • In this paper, we suggest a new distribution model for a single phase transformer which is different from the existing model which was modeled for only primary parts, but new distribution model is modeled for primary and secondary parts. Using this model, we simulate various faults of the transformer to know how the transfer function vary from the normal one, i.e., the trend of the variation of transfer function. As an another approach, we measure the voltage and current of a three phase transformer while various faults are made at the transformer. From the simulation of the model and experiment, we fine some trends of the variation of transfer function.

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