• Title/Summary/Keyword: Time Scales

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Transient Evolution of Overlapped EDL Fields in a Microfluidic Channel (미소유동 채널에서 중첩된 전기이중층 구조의 과도 형성과정)

  • Kwak, Ho-Sang;Hasselbrink, Jr., Ernest F.
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1528-1533
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    • 2004
  • A numerical investigation is made of transient evolutionary prcocess of electroosmotic flow in a two-dimensional microchannel connected to a reservoir. The channel height is very small so that two electric double layers forming on the charged surfaces are overlapped. Transient transports of ions in the electrolyte solution are computed by integrating the Nernst-Planck equation together with the Poisson equation for electric potential. The numerical results illustrate that there are two distinct transient phases. The physical mechanisms and relevant time scales for the transient evolution are described.

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Developement of Measuring System of Circular Motion Accuracy in Machining Center (머시닝 센터에서 원운동정도 측정시스템의 개발)

  • 김영석
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.4 no.3
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    • pp.58-66
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    • 1995
  • It is very important to test motion accuracy and performance of NC machine tools as they affect that of all other machines machined by them in industry. In this paper, in has become possible to detect errors of linear displacement of radial direction for circular motion test using newly assembled magnetic type of linear scales so called Magnescale ball bar system, and to calculate time interval getting error motion data and revolution angle of circular motion in machining center using tick pulses come out from computer. And a set of error data gotten from test is expressed to a plot by computer treatment and to numerics of error motion by statistical treatment and results of test are compared with those of Renishaw ball bar system.

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Patterns of Vertical Distribution and Diel Vertical Migration of Zooplankton in the East Sea of Korea (Sea of Japan)

  • Park, Chul;Lee, Chang-Rae;Hong, Sung-Yun
    • Journal of the korean society of oceanography
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    • v.32 no.1
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    • pp.38-45
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    • 1997
  • To find out the changes in vertical distribution patterns over the 24-h period, a key and the first step to tackle the problem of adaptive significance of diel vertical migration (DVM), vertically stratified time series samplings with multiple opening/closing plankton samplers were done in the East Sea of Korea (Sea of Japan). Sampling was done almost every 4 h for one day period following the same water parcel in Nov. 1995 and May 1996, respectively. Resultant patterns of vertical distribution showed that some species such as most abundant taxa Metridia pacifica and Scolecithyicella minor, both Copepoda, performed DVM even in the study area of strong thermal stratification. Their patterns of DVM such as distance scales and timing of movements were not the same each other, and they were separated from other taxa in the dendrogram obtained by the cluster analyses, Most minor taxa grouped in one, however, seemed not to do DVM in the study area of strong thermal stratification. They usually preferred the warmer surface layer where the foods were probably more abundant.

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A Survay of Satisfaction of Physical Therapy Patients in Kwang-ju (광주지역내 물리치료실 이용 환자의 물리치료 만족도 조사)

  • Kwon Mi-Ji;Kim Seok Hwan
    • The Journal of Korean Physical Therapy
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    • v.15 no.2
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    • pp.1-11
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    • 2003
  • Patients satisfaction continues to receive attention as a measure of the outcome of physical therapy intervention. This study measures patient satisfaction among physical therapists' patients and clients and to identify factors of patient satisfaction that will affect patients decision. The instrument developed by Goldstein et. al(2000) was used. PAtients' opinions of service in each domain were measured using 5-point Likert-type scales. A 20-item instrument designed to measure the domains of patient satisfaction and 8 additional items were included. Data were collected at 8 hospital in Kwang-ju city Descriptive statistics, reliability, ANOVA, cross-tabs and regression analysis were computed. A total 365 individuals completed the instrument. Waiting time, treatment and cost domain predicted the satisfaction of physical therapy

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Drought Analyses of 1994 Using Standardized Precipitation Index (SPI를 이용한 1994년 가뭄분석)

  • 김상민;박승우;김현준
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • 1998.10a
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    • pp.92-98
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    • 1998
  • Among several indices that have been proposed and adopted in different disciplines of sciences, standardized precipitation index, SPI by McKee et al. (1993) was applied to evaluate drought severity for historical rainfall records. Monthly SPI in Seoul station was reviewed in this study, in an effort to characterize the drought intensities during 1994. The SPI drought frequency decreases inversely with monthly time scales of different spans, while the drought duration increases. March, 1994 was found to be the most severe for the three month period, and was recognized as the beginning month of the historical drought spans. Drought intensities became less severe during May and June. SPI becomes greater from July to September particularly in eastern parts of the country.

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Air-Sea Heat Flux Estimation by Ocean Data Assimilation Using Satellite and TOGA/TAO Buoy Data

  • Awaji, Toshiyuki;Ishikawa, Yoichi;Iida, Masatora;In, Teiji
    • Proceedings of the KSRS Conference
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    • 1999.11a
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    • pp.221-226
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    • 1999
  • A data assimilation system for a 1-dimensional mixed layer model has been constructed using the adjoint method. The classical adjoint method does not work well for the mixed layer variabilities due to the occurrence of spikes in the gradient of the cost function. To solve this problem, the two techniques of scaling the cost function and optimization in the frequency space are used. As a result, the heat flux can be reliably estimated with an accuracy of 8Wm$^{-2}$ rms error in the identical twin experiments. We then applied this system to the tropical Pacific TOGA-TAO buoy data. The air-sea heat flux as well as the mixed layer variability were estimated in close approximation to the buoy data, particularly on time scales longer than the seasonal one.

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The Development of the Design Guideline and the Comparative Evaluation For the Remanufacturing of a Cellular Phone (휴대폰 재제조를 위한 친환경 설계 지침 개발 및 비교 평가)

  • 김찬석;이화조
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.1029-1033
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    • 2004
  • Concern over the negative environmental impacts associated with the production, use and End-of-Life(EoL) of cellular phones is particularly high due to large production volumes and characteristically short time scales of technological and stylistic obsolescence. Therefore we have to research the environment-friendly technologies and the recycling methods. This paper introduces an improvement of cellular phone remanufacturing processes and develops the Directive of DFE(Design for Environment) for the remanufacturing of a cellular phone. Then We discuss the results of the comparative evaluations.

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High-Temperature Oxidation Behavior of Commercial Pure Titanium in Mixed Gases (혼합가스 분위기 중에서 공업용 순 타이타늄의 고온산화 거동)

  • Park, S.H.;Ahn, Y.S.
    • Journal of Power System Engineering
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    • v.11 no.2
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    • pp.44-50
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    • 2007
  • The oxidation behavior of commercial pure titanium is investigated in the temperature range of $727^{\circ}C{\sim}950^{\circ}C$ in mixed gases. The weight change is measured by TGA during oxidation in mixed gases. The oxidation behavior indicated by weight gain or the growth of oxide layer is based on the linear rate law at high temperatures. The structure of the oxide scale formed during oxidation is analysed by optical microscopy, electron probe microanalyzer, scanning electron microscope and x-ray diffraction. Oxide scales have a $TiO_2$ structure, and are constituted with multi-layered or two layered porous external one and a dense internal one. Ti-O solid solution region is formed at the interface of metal and scale layer. The formation of oxide scale is influenced by the oxidation temperature, time, crystal structure and the condition of atmosphere.

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Implementation of an Intelligent Learning Controller for Gait Control of Biped Walking Robot (이족보행로봇의 걸음새 제어를 위한 지능형 학습 제어기의 구현)

  • Lim, Dong-Cheol;Kuc, Tae-Yong
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.59 no.1
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    • pp.29-34
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    • 2010
  • This paper presents an intelligent learning controller for repetitive walking motion of biped walking robot. The proposed learning controller consists of an iterative learning controller and a direct learning controller. In the iterative learning controller, the PID feedback controller takes part in stabilizing the learning control system while the feedforward learning controller plays a role in compensating for the nonlinearity of uncertain biped walking robot. In the direct learning controller, the desired learning input for new joint trajectories with different time scales from the learned ones is generated directly based on the previous learned input profiles obtained from the iterative learning process. The effectiveness and tracking performance of the proposed learning controller to biped robotic motion is shown by mathematical analysis and computer simulation with 12 DOF biped walking robot.

A Singular Perturbation-Like Approach to EDFA Gain Control Based on Observer Techniques

  • Song, Seong-Ho;Chang, Dong Eui;Lee, Kwang Y.;Kim, Ho-Chan
    • Journal of Electrical Engineering and Technology
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    • v.10 no.4
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    • pp.1864-1876
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    • 2015
  • In this paper, we propose a singular perturbation-like approach to EDFA gain controller design and analysis. Considering a three-level model of EDFA, a gain controller containing a state observer and a channel add/drop estimator is designed based on a singular perturbation - like concept. The proposed design methodology is shown to be effective and advantageous not only in theoretically verifying the asymptotic stability of systems with multi-time scales such as EDFA but also in designing an asymptotic estimator for channel add/drops which does not satisfy the matching condition.