• Title, Summary, Keyword: Decay Function

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An empirical study on the effect of distance decay for the relocated firms using distance-decay function by industrial types in the Seoul Metropolitan Area (거리조락함수를 이용한 수도권 지역간 기업이동 거리감쇄효과 실증 연구)

  • An, Youngsoo;Lee, Seungil
    • Journal of the Korean Regional Science Association
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    • v.31 no.2
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    • pp.47-61
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    • 2015
  • The purpose of this study to empirical analysis of the effects of distance-decay for the relocated firms in the Seoul Metropolitan Area(SMA). In addition, this study was constructed distance-decay function for the relocated firms by industrial types using a general distance-decay function. The data of relocated firms in the SMA extracted from the spatial database which was constructed in an previous research. The industrial type divided into 3 parts which are construction, manufacturing, and service. The result of empirical analysis by each industrial type of the effect of distance-decay, the explanatory power($R^2$) of the each function were all high. In the construction, the adjusted $R^2$ of the distance-decay function was 0.728, the manufacturing was 0.802 and the service was 0.812. It means the effect of distance decay for the relocated firms in construction industrial type more big than the effects of distance decay for the manufacturing and service industrial types.

Study on the Formulation of Two Dimensional Infinite Elements (이차원 무한요소 형성에 관한 연구)

  • 신용태;임장근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.5
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    • pp.1066-1073
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    • 1993
  • Using regular finite elements and infinite elements simultaneously, elastic boundary value problems with infinite domain can be analyzed more effectively and accurately. In this paper, two dimensional infinite elements have been formulated by means of applying the derived mapping function to the coordinates and multiplying the regular displacement shape functions by a decay function. Orders(m, n) of the mapping and decay functions are found for the purpose of obtaining the convergent solutions without respect to the various decay lengthes. As a result of numerical tests for an infinite plate with a hole under internal pressure, two sets of function orders are obtained as follows. (a) n=0, m=1.5 (b) n=m=0.65

Mechanical degradation kinetics of poly(ethylene oxide) in a turbulent flow

  • Sung, Jun-Hee;Lim, Sung-Taek;Kim, Chul-Am;Heejeong Chung;Park, Hyoung-Jin
    • Korea-Australia Rheology Journal
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    • v.16 no.2
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    • pp.57-62
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    • 2004
  • Turbulent drag reduction (DR) efficiency of water soluble poly(ethylene oxide) (PEO) with two different molecular weights was studied as a function of polymer concentration and temperature in a turbulent flow produced via a rotating disk system. Its mechanical degradation behavior as a function of time in a turbulent flow was also analyzed using both a simple exponential decay function and a fractional exponential decay equation. The fractional exponential decay equation was found to fit the experimental data better than the simple exponential decay function. Its thermal degradation further exhibited that the susceptibility of PEO to degradation increases dramatically with increasing temperature.

GLOBAL EXISTENCE AND STABILITY FOR EULER-BERNOULLI BEAM EQUATION WITH MEMORY CONDITION AT THE BOUNDARY

  • Park, Jong-Yeoul;Kim, Joung-Ae
    • Journal of the Korean Mathematical Society
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    • v.42 no.6
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    • pp.1137-1152
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    • 2005
  • In this article we prove the existence of the solution to the mixed problem for Euler-Bernoulli beam equation with memory condition at the boundary and we study the asymptotic behavior of the corresponding solutions. We proved that the energy decay with the same rate of decay of the relaxation function, that is, the energy decays exponentially when the relaxation function decay exponentially and polynomially when the relaxation function decay polynomially.

A Study of a Decay Parameter for the Dark Adaptation Function on the retina (망막에서 암순응 함수의 Decay parameter 연구)

  • Kim, Yong Geun
    • Journal of Korean Ophthalmic Optics Society
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    • v.5 no.2
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    • pp.145-150
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    • 2000
  • The adaptation for a right source on the retina consists of the light-dark adaptation's two curves for a time by the rod-cone receptor. We obtained the adaptation for a time to measure the threshold intensities, it was two decay curves by the center of a rod-cone break. It could be represented the dark adaptation by a exponential decay function consisting of $T_{min}$, $a_r$, $a_c$, $T_{0(r)}$, $T_{0(c)}$, $t_b$, $t_c$'s parameters. The curves of a $t_b$ below and a $t_b$ above showed the adaptation sensitivity of the cone and the rod. The exponential decay function was well applied to the dark adaptation in difference retinal positions, in contrally fixated fields, in luminous, as age etc. It could be used the decay parameter as the index because of representing the properties of the dark adaptation's function.

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Simulation of chlorine decay by waterhammer in water distribution system based on hypothetical water demand curve (가상의 물 수요곡선에 따른 수충격에 의한 염소농도변동 모의연구)

  • Baek, Dawon;Kim, Hyunjun;Kim, Sanghyun
    • Journal of Korean Society of Water and Wastewater
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    • v.32 no.2
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    • pp.107-113
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    • 2018
  • Maintaining adequate residual chlorine concentration is an important criteria to provide secure drinking water. The chlorine decay can be influenced by unstable flow due to the transient event caused by operation of hydraulic devices in the pipeline system. In order to understand the relationship between the transient event and the chlorine decay, the probability density function based on the water demand curve of a hypothetical water distribution system was used. The irregular transient events and the same number of events with regular interval were assumed and the fate of chlorine decay was compared. The chlorine decay was modeled using a generic chlorine decay model with optimized parameters to minimize the root mean square error between the experimental chlorine concentration and the simulated chlorine concentration using genetic algorithm. As a result, the chlorine decay can be determined through the number of transients regardless of the occurrence intervals.

A Preparation of Copper Phthalocyanine Photoreceptor by an Aqueous Coating Method and Study of Dark Decay and Photoinjection Efficiency (신규 제작법을 이용한 Copper Phthalocyanine 전자사진 감광체의 개발과 Dark Decay와 Photoinjection Efficiency에 관한 연구)

  • 이상남
    • Journal of the Korean Printing Society
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    • v.11 no.1
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    • pp.103-122
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    • 1993
  • A cause and counterplan of the increase in dark decay rate of$\varepsilon$-CuPc/PVCz photoreceptor which is consist of the carrier generation layer (CGL) of$\varepsilon$type copper phthalocyanine ($\varepsilon$-CuPc) thin film by an aqueous coating method and the carrier transport layer (CTL) of polyvinylcarbazol (PVCz) by spin coating, are studied in this paper. Electrochemical deposition of CGL was accompanied by an increase in work function of the aluminium substrate during the processes and the enhanced work function 5.3 eV rose above the ionization potential 5.16 eV of $\varepsilon$-CuPc. This resulted in the increased injection of holes from substrate into CGL and a fast dark decay rate. Improved photoreceptor, an electron-transport $\varepsilon$-CuPc/TNF photoreceptor, led to lowing of dark decay rate and increasing of photosensitivity. The carrier generation efficiency (ηg), carrier injection efficiency (ηi) and xerographic gain (G) of the $\varepsilon$-CuPc/TNF photoreceptor were obtained by XTOF method and PIDC.

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A Comparative Study on Coupling of Element-free Galerkin Method and Infinite Element by IE's Shape Function (무한요소 형상함수에 따른 무요소법과의 조합 방법 비교 연구)

  • 이상호;김명원;윤영철
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.279-287
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    • 2003
  • This paper deals with a comparative study on coupling of Element-free Galerkin(EFG) method and Infinite Element(IE) by IE's shape function. In this study, mapped infinite elements(mapped IE) and decay function infinite elements(decay IE) are coupled with the EFG method. A coupling procedure of EFG-Mapped IE is much easier to be integrated than a coupled EFG-Decay IE. A coupled EFG-IE method used well-defined functions to preserve the continuity and linear consistency on the interface of the EFG region and IE region. Several benchmark problems are solved to verify the effectiveness and accuracy of the coupling algorithms by IE's shape function. The numerical results show that the developed algorithms work well for the elastic problems with infinite boundaries.

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Application of the Projection Operator Technique to the Study of NMR Line Shape and Free Induction Decay Curve (NMR 吸收線 모양과 誘導磁氣自由減衰曲線 硏究에의 投影演算子法의 應用)

  • Lee Jo W.;Sung Nak Jun
    • Journal of the Korean Chemical Society
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    • v.21 no.5
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    • pp.362-371
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    • 1977
  • In this paper application of the projection operator technique to the study of NMR absorption line shape and free induction decay curve is explored. It is found that the projection operator technique can provide a convenient means for deriving a set of hierarchy equations which may serve as a good starting point for theoretical calculation of the absorption line and free induction decay function by successive approximation or by an appropriate decoupling approximation. A brief review of linear response theory of NMR line shape and the relation between the absorption line shape and free induction decay function are also described.

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ULTRAFAST INTERFACIAL ELECTRON TRAPPING AND RECOMBINATION IN PHOTOEXCITED COLLOIDAL CADMIUM SULFIDE

  • Kim, Seong-Kyu
    • Journal of Photoscience
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    • v.4 no.1
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    • pp.11-16
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    • 1997
  • We measured, using femtosecond pump-probe experiment, the time evolution of transient absorption in aqueous CdS colloids. The signal rises within the time resolution (= 0.5 ps) of the experiment and decays with two exponential time constants, 4.8 ps and 132 ps. The ultrafast rise of the transient absorption is considered to be for shallowly trapped conduction band electrons after photoexcitation. The amplitude ratio of the two decaying components varies with the pump intensity and the decay times increase in the presence of hole scavengers. Even though a biexponential function fits the decay well, we object hat two independent first order processes (geminate and nongeminate recombinations) are responsible for the decay. A function with an integrated rate equation for second order nongeminate recombination plus a long background fits the decay well. The long background is considered to be for deeply trapped charges at the CdS particle.

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