• Title/Summary/Keyword: Difference

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The Study on Detecting Scheme of Voltage Sag using the Two Difference Voltage (이중 차 전압을 이용한 전압 새그 검출 기법에 관한 연구)

  • Lee, Woo-Cheol
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.12
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    • pp.65-73
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    • 2014
  • In this paper, the detection scheme of the voltage variation using a two difference voltage is proposed. The conventional sag detector is from a single-phase digital phase-locked loop (DPLL) that is based on a d-q transformation using an all-pass filter (APF). The APF generates a virtual q-axis voltage component with $90^{\circ}$ phase delay but the APF cannot generate the virtual q-axis voltage depending on the phase of the grid voltage. To overcome the problem, q-axis voltage component is generated from difference between the current and previous value of d-axis voltage component in the stationary reference frame. However, the difference voltage around the zero crossing is not enough to detect the voltage sag. Therefore, the new detection scheme using the two difference voltage which can detect the sag around the zero crossing voltage is proposed.

A Current Differential Relay for Transformer Protection with a Blocking Method Using the Difference-Function of a Differential Current (차전류 차분 블로킹 변압기 보호용 전류차동 계전기)

  • 강용철;원성호;김대성;양성채
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.12
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    • pp.691-697
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    • 2003
  • This paper proposes a current differential relay for transformer protection that operates in accordance with a blocking method based on the difference-function of a differential current. For magnetic inrush and over-excitation, discontinuities in the first-difference function of the differential current arise at the points of inflection, which correspond to the start and end of each saturation period of the core. These discontinuities are converted into the pulses in the second- and third-difference functions of the differential current. The magnitudes of the pulses are large enough to detect saturation of the core. A blocking signal is issued if the magnitude of the third-difference function exceeds the threshold and is maintained for three quarters of a cycle. The performance of the relay is assessed under various conditions with magnetic inrush, internal faults and external faults. The proposed blocking method can improve significantly the operating time of a relay and achieve high sensitivity of a relay.

Pointing position detection of capacitive touch screen panel using phase-difference method (위상차 방식을 사용한 용량방식 터치 스크린 패널의 접촉 위치 검출)

  • Jo, Yeong-Cheol;Jang, Rae-Hyeok;Gwon, Uk-Hyeon
    • Journal of Institute of Control, Robotics and Systems
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    • v.4 no.3
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    • pp.406-412
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    • 1998
  • This paper describes a contact position detection method of a capacitive touch screen panel. The proposed method is composed of a circuited compensating algorithm generating an output signal having phase difference to an input signal associated with contact position, converts both input and output signals into digital waveform (5V logic), and calculates the phase difference. Finally, position information with the phase difference is obtained by using a low-cost microprocessor, which is convenient to compensate non-linearity error. The proposed method, that computes phase difference directly, has advantages in feasibility and cost because it minimizes the use of analog devices; rather, it utilizes, cost effective digital circuit. Analytical results are also given.

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Characteristics of Ultrasonic Motor using Voltage Control and Phase Difference Control (초음파 모터의 전압 및 위상차 제어 특성)

  • Shin, Duk;Kim, Dong-Ok;Ko, Nak-Yong;Choi, Han-Soo;Kim, Young-Dong
    • Proceedings of the KIEE Conference
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    • 1996.07b
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    • pp.949-952
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    • 1996
  • The ultrasonic motor(USM) has good characteristics such as compact size, silent motion, low speed, high torque and high speed response. The USM is driven by 2-phase AC electricity. The control parameters of USM are voltage, phase difference, frequency of input power, etc. In this paper, we propose voltage difference control. And we designed USM controller to adjust voltage and phase using pLSI(programmable Large Scale Integration). Voltage difference control has many advantages that are lower current, lower power than phase difference control. Especially there is nearly zero ampere at the zero point of speed and torque. we can apply this voltage difference control to the compliance control of DD manipulator.

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Biomechanical Analysis of Soccer Shoes According to the Difference of Stud (스터드 차이에 따른 축구화의 운동역학적 변인 비교)

  • Jin, Young-Wan
    • Korean Journal of Applied Biomechanics
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    • v.24 no.4
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    • pp.455-461
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    • 2014
  • The purposes of this study were to reveal the kinematic and kinetic difference of hard ground soccer shoe, firm ground soccer shoe and soft ground soccer shoe. Soccer players were shoes of varying stud designs with some preferring the bladed studs while others opting for the conventional studded stud. Statistics were used one way-ANOVA and Tukey's Honestly Significant Difference Method. Seven healthy college soccer players were attended a test. All parameters were recorded using the Zebris system. Spatio-temporal variables were no significant difference. Lateral symmetry was statistically significant differences (p<.05). Vertical GRF parameters were no significant difference. Medial midfoot pressure, lateral midfoot pressure and central forefoot pressure were statistically significant differences (p<.05). This study demonstrates that playing surface significantly affects difference soccer shoes during soccer game. Furthermore, epidemiological investigation is warranted to determine the effects of playing surfaces on sport specific injury mechanisms.

A phenomenological approach to suspensions with viscoelastic matrices

  • Tanner Roger I.;Qi Fuzhong
    • Korea-Australia Rheology Journal
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    • v.17 no.4
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    • pp.149-156
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    • 2005
  • A simple constitutive model for viscoelastic suspensions is discussed in this paper. The model can be used to predict the rheological properties (relative viscosity and all stresses) for viscoelastic suspensions in shear and elongational flow, and the constitutive equations combine a 'viscoelastic' behaviour component and a 'Newtonian' behaviour component. As expected, the model gives a prediction of positive first normal stress difference and negative second normal stress difference; the dimensionless first normal stress difference strongly depends on the shear rate and decreases with the volume fraction of solid phase, but the dimensionless second normal stress difference (in magnitude) is nearly independent of the shear rate and increases with the volume fraction. The relative viscosities and all the stresses have been tested against available experimental measurements.

A Study about Direction Estimate Device of the Sound Source using Input Time Difference by Microphones′ Arrangement (마이크로폰 배열로 발생되는 입력 시간차를 이용한 음원의 방향 추정 장치에 관한 연구)

  • 윤준호;최기훈;유재명
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.5
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    • pp.91-98
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    • 2004
  • Human uses level difference and time difference to get space information. Therefore this paper shows that method to presume direction of sound source by time difference and to mark presumed position. The position means direction from geometrical center of sensors to the sound source. To get the time difference of microphones input level, we will be explained about arrangement of microphones which used for the sensor to take the sound signal. It is included distance among the 3 microphones and distance between microphones and sound source. Secondly, input signals are transmitted to CPU througth digital process. CPU is used to DSP(Digital Signal Processor) for manage the signal by real time. Finally, the position of sound source is perceived by an explained algorithm in this paper.

ENTIRE SOLUTIONS OF DIFFERENTIAL-DIFFERENCE EQUATION AND FERMAT TYPE q-DIFFERENCE DIFFERENTIAL EQUATIONS

  • CHEN, MIN FENG;GAO, ZONG SHENG
    • Communications of the Korean Mathematical Society
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    • v.30 no.4
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    • pp.447-456
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    • 2015
  • In this paper, we investigate the differential-difference equation $(f(z+c)-f(z))^2+P(z)^2(f^{(k)}(z))^2=Q(z)$, where P(z), Q(z) are nonzero polynomials. In addition, we also investigate Fermat type q-difference differential equations $f(qz)^2+(f^{(k)}(z))^2=1$ and $(f(qz)-f(z))^2+(f^{(k)}(z))^2=1$. If the above equations admit a transcendental entire solution of finite order, then we can obtain the precise expression of the solution.

New approach method of finite difference formulas for control algorithm (제어 알고리즘 구현을 위한 새로운 미분값 유도 방법)

  • Kim, Tae-Yeop
    • Journal of IKEEE
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    • v.23 no.3
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    • pp.817-825
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    • 2019
  • Difference equation is useful for control algorithm in the microprocessor. To approximate a derivative values from sampled data, it is used the methods of forward, backward and central differences. The key of computing discrete derivative values is the finite difference coefficient. The focus of this paper is a new approach method of finite difference formula. And we apply the proposed method to the recursive least squares(RLS) algorithm.

SOME NEW CLASSES OF ZERO-DIFFERENCE BALANCED FUNCTIONS AND RELATED CONSTANT COMPOSITION CODES

  • Sankhadip, Roy
    • Bulletin of the Korean Mathematical Society
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    • v.59 no.6
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    • pp.1327-1337
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    • 2022
  • Zero-difference balanced (ZDB) functions can be applied to many areas like optimal constant composition codes, optimal frequency hopping sequences etc. Moreover, it has been shown that the image set of some ZDB functions is a regular partial difference set, and hence provides strongly regular graphs. Besides, perfect nonlinear functions are zero-difference balanced functions. However, the converse is not true in general. In this paper, we use the decomposition of cyclotomic polynomials into irreducible factors over 𝔽p, where p is an odd prime to generalize some recent results on ZDB functions. Also we extend a result introduced by Claude et al. [3] regarding zero-difference-p-balanced functions over 𝔽pn. Eventually, we use these results to construct some optimal constant composition codes.