• Title/Summary/Keyword: Difference Time Gap

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Time Difference Characteristics of GPS Carrier Phase (GPS 반송파의 시각차분 특성)

  • You, Ho;Lee, Eun-Sung;Lee, Young-Jea;Jee, Gyu-In;Nam, Gi-Wook;Jun, Hyang-Sig
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.9
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    • pp.66-72
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    • 2005
  • As one of the methods that determine position using GPS carrier phase without the resolution of integer ambiguity, the characteristics of the time difference is analyzed in this paper. When determining position by the needed accuracy, the difference time gap becomes an important factor. It is said that accuracy is improved as the difference time gap is getting large, and finally the centimeter level accuracy is achieved after a certain difference time gap. In this paper, the characteristics of the time difference is analyzed using real data and a new parameter is proposed to predict the resulting position accuracy. The difference time gap when position error is converged to the centimeter level is estimated with the proposed parameter.

Effective Sensing Volume of Terahertz Metamaterial with Various Gap Widths

  • Park, Sae June;Yoon, Sae A Na;Ahn, Yeong Hwan
    • Journal of the Optical Society of Korea
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    • v.20 no.5
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    • pp.628-632
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    • 2016
  • We studied experimentally and theoretically the vertical range of the confined electric field in the gap area of metamaterials, which was analyzed for various gap widths using terahertz time-domain spectroscopy. We measured the resonant frequency as a function of the thickness of poly(methyl methacrylate) in the range 0 to 3.2 μm to quantify the effective detection volumes. We found that the effective vertical range of the metamaterial is determined by the size of the gap width. The vertical range was found to decrease as the gap width of the metamaterial decreases, whereas the sensitivity is enhanced as the gap width decreases due to the highly concentrated electric field. Our experimental findings are in good agreement with the finite-difference time-domain simulation results. Finally, a numerical expression was obtained for the vertical range as a function of the gap width. This expression is expected to be very useful for optimizing the sensing efficiency.

Differential in Married Women's Perceived Time Pressure by Employment : Testing the Effects of Couple Time Use and Housework Outsourcing (기혼여성의 취업여부에 따른 시간압박감과 관련요인의 차이 : 아내의 시간, 남편의 시간, 그리고 가사노동 사회화의 효과)

  • Cha, Seung-Eun
    • Journal of Families and Better Life
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    • v.33 no.5
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    • pp.37-53
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    • 2015
  • The purpose of this study is to examine the differences in perceived time pressure between employed and non-employed married women in Korea. The sample of married couple from the Korean Time Use Survey 2009 (n = 6,948 couple diaries) was used to examined the difference in the level of perceived time pressure over the life cycle of two group. This study also investigated the married women's time use, husband's time use as well as hour of domestic outsourcing and whether such factors are associated with lowering perceived time pressure of married women. Results showed employed wives felt almost 3 times more time pressed than non-employed wives, and the gap mostly remained over different life cycles. Total work hours were associated with increasing the time pressure of both groups of women, while regenerating time was associated with ameliorating time pressure. The result suggests that the time pressure gap between employed and non-employed wives can be partly due to the relative length of total labor hours and regenerating time among the two groups. Ordered logit analysis revealed that husband's paid work hours were not associated with wive's feeling rushed, but husband' unpaid work hours were positively linked with time pressure of their wives. Results indicated if employed or non-employed wives are feeling very busy, there is a high chance that husband might give them some help. We found employed wives spend more hours on housework outsourcing, and purchasing goods for housework was not associated with lowering the feeling of pressure of employed wives. There were both similarity and difference in factors associated with women's feeling pressed among employed and non-employed wives. It implies that social process and it's strategies to alleviate the time pressure can be different by women's employment status.

Developement of 3-D Vision Monitoring System for Tailored Blank Welding (맞춤판재 용접용 3차원 비젼 감시기 개발)

  • Jang, Young-Gun;Lee, Keung-Don
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.12
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    • pp.17-23
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    • 1997
  • A 3-D vision system is developed to evaluate blanks' line up and monitor gap and thickness difference between blanks in tailored blank welding system. A structured lighting method is used for 3-D vision recognition. Images of sheared portion in blanks are irregular according to roughness of blank surface, shape of sheared geometry and blurring. It is difficult to get accurate and reliable informations in the case of using binary image processing or contour detection techniques in real time for such images. We propoe a new energy integration method robust to blurring and changes of illumination. The method is computationally simple, and uses feature restoration concept, different to another digital image restoration methods which aim image itself restoration and may be used in conventional applications using structured line lighting technique. Experimental results show this system measuring repeatability is .+-. pixel for gap and thickness difference in static and dynamic tests. The data are expected to be useful for preview gap control.

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The Effect of Ground Plane Gap on the Radiated Emission (PCB 접지면 갭이 불요전자파 방사에 미치는 영향)

  • 하재경;김형훈;김형동
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.9 no.5
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    • pp.648-658
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    • 1998
  • In this paper, the effect of the gap in the ground plane on the electromagnetic interference (EMI) is analyzed quantitatively. Because of a lot of advantages compared to other numerical techniques, the FDTD (finite difference time domain) is applied to the EMI effect modeling. The analyzed model is the simplified PCB (printed circuit board) which has a microstrip and ground plane. The inductance induced by the gap is modeled and calculated by gridding the whole PCB based on the FDTD algorithm. When external cables are attached to the PCB, the common-mode current is induced along the attached cable and the resulting electric field strength is calculated and presented along with the FCC and CISPR EMI limits. The results show that the radiated field strength highly depends on the size of the ground plane gap. The numerical simulation results can be used as a reference in the practical PCB design with the ground plane gap.

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A Study on the Application of Macro Air-gap Element for Magnetic Flux Distribution Analysis of Electric Machinery by F.E.M. (유한요소법에 의한 전기기계의 자속분포해석을 위한 MACRO 공선요소 적용에 관한 연구)

  • Dal-Ho Im
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.35 no.11
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    • pp.479-486
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    • 1986
  • It is necessary to consider a rotor movement in dynamic analysis on the flux distribution of electric machinery by FEM. Therefore, if air-gap domain was subdivided into triangular elements, computation results contain errors due to variation of element shape in air-gap because the nodal points corresponding to the rotor are displaced in analyzing domain for the time difference. In order to reduce this errors, the paper presents a application of a Macro Air-gap Element that interpolation function is obtained analytically and a means to join it with linear triangular elements in the rotating machine or in the linear machine. At the end of paper, setting up analytic domain model, it compares analytic solution with the computation results of Macro Air-gap Element appliction and that of linear triangular element subdivision only to each cases of nodal displacement. And it carries out that errors due to variation of element shape are reduced effectively by application of a Macro air-gap element.

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A Comparative Study on Interrelation between FDTD Source Models for Coaxial-Probe Feeding Structures (동축 프로브 급전구조에 대한 FDTD 전원 모델들의 상호 관계에 관한 비교 연구)

  • Hyun, Seung-Yeup
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.25 no.1
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    • pp.114-122
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    • 2014
  • For an efficient finite-difference time-domain(FDTD) analysis of coaxial-probe feeding structures in radio frequency(RF) and microwave bands, an interrelation between equivalent source modeling techniques is investigated. In existing literature, equivalent source models with delta-gap or magnetic-frill concepts have been developed by many researchers. It is well known that FDTD implementation and computational accuracy of these source models are slightly different. In this paper, the interrelation between FDTD equivalent source models for coaxial feeding structures under the quasi-static approximation(QSA) is presented. As a function of FDTD equivalent source models, time-domain and frequency-domain responses of a coaxial-probe fed conical monopole antenna are calculated numerically. And comparison results of computational accuracy and efficiency are provided.

Air Gap Measurement in Homogeneous Material by Non-contact and Non-destructive Method (비접촉 비파괴에 의한 균일물질 내부의 공극 측정)

  • 전태인
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 1999.05a
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    • pp.47-49
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    • 1999
  • The air and impurity gaps generated by a defect in homogeneous material have a difference index of refraction compare to the homogeneous material. Therefore an electromagnetic wave has a multiple reflection between the two indices of refraction. If the gap has a small thickness, it is difficult to know the gap in time domain. However, the presence of the gaps can be known in frequency domain by total transmission and phase difference. Also, the thickness and index of refraction can be measured by well known Febry-Perot theory.

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Design and Analysis of Gap Coupled Microstrip Patch Antenna using the FDTD method (유한차분 시간영역법을 이용한 갭 결합 마이크로 스트립 패치안테나의 설계 및 해석)

  • Shin, Ho-Sub
    • Journal of Digital Contents Society
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    • v.10 no.3
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    • pp.389-393
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    • 2009
  • In this paper, the single patch microstrip antenna and gap coupled broadband microstrip patch antenna using FDTD(Finite Difference Time Domain method) are analyzed. Mur's 2nd absorbing boundary condition to minimize reflected wave is applied. Return loss, voltage standing wave ratio, and input impedance by the length and width of driving patch, the length and width of parasitic patch, and the distance between driving patch and parasitic patch have been analyzed. Design parameters and radiation patterns of broadband antenna have been also shown.

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A Study of the Characteristics on the Vacuum Interrupter with Axial Magnetic Field Type using 3 Dimension Finite Element Analysis (3차원 유한요소해석을 이용한 종자게형 진공 인터럽터의 특성고찰)

  • 하덕용;강형부
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.5
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    • pp.460-467
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    • 2002
  • This paper deals with the distribution characteristics of the current density and axial magnetic flux density on the vacuum interrupter with axial magnetic field type using 3 dimension finite element analysis. An axial magnetic field parallel to the current flow in the arc column can improve the current breaking capacity of vacuum interrupter by affecting the arc mode. The axial magnetic flux density on the contact electrode surface is analyzed by inputting external current as a function of the transient time for sine half wave. And it also is analyzed within the gap distance of the contact electrode. The peak value of current but is decreased with the descending current on the contact electrode surface and within the gap distance of the contact electrode. The residual magnetic field is generated on the contact electrode surface and within the gap distance in the instant of zero current, which is due to the influence of eddy currents. The phase shift due to eddy currents, defined as time difference between the maximum value of current and axial magnetic field, is about 1ms in the center point of gap distance.