• Title, Summary, Keyword: Rectangular cell

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A Study on Lohmann Type Computer Generated Holograms Using a Circular Cell (원형 셀을 이용한 Lohmann형 컴퓨터 형성 홀로그램에 관한 연구)

  • Seo, Choon-Su;Jeong, Man-Ho
    • Korean Journal of Optics and Photonics
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    • v.17 no.6
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    • pp.519-524
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    • 2006
  • In general, the Lohmann-type binary hologram represents its amplitude and phase by using the rectangular cell. In this paper, we adapts a circular cell to represents the amplitude and phase of holograms. In order to compare the characteristics of the circular cell with the rectangular one, we analyzed the results based on the computer simulations and various optical experiments. The results show that a clearer reconstructed image can be obtained by dividing one cell into many pixels. In the case of a uniform reconstructed image, the rectangular cell is better than the circular cell. However, as for the brightness of the reconstructed image, the circular cell is better than the rectangular one.

Dispersion Analysis for Rectangular Coaxial Line and TEM Cell (네모 동축선과 TEM 셀의 분산관계 해석)

  • Cho, Yong-Heui
    • The Journal of the Korea Contents Association
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    • v.7 no.1
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    • pp.124-130
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    • 2007
  • A rectangular coaxial line is mainly utilized as a transition structure from a coaxial line to a rectangular waveguide. A TEM cell is also widely used to measure the EMC characteristics of a DUT. In order to understand the operations of a rectangular coaxial line and a TEM cell, it is essential to analyze the dispersion relations of a rectangular coaxial line and a TEM cell. In this paper, we present simple yet accurate dispersion relations of the TE and TM higher modes based on the TEM mode. Manipulating a mode-matching technique and a Green's function approach allows us to obtain the analytic dispersion equations of a rectangular coaxial line and a TEM cell. In our approach, a rectangular coaxial line is divided into four L-blocks and its electromagnetic fields representations are easily obtained with a superposition. To verify the convergence of our dispersion relations, we perform numerical computations and compare our results with those of FDTD.

Triangular Cell Map Based Complete Coverage Navigation Method for Cleaning Robot

  • Oh, Joon-Seop;Park, Jin-Bae;Park, Yoon-Ho
    • 제어로봇시스템학회:학술대회논문집
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    • pp.129.3-129
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    • 2001
  • In this paper, a novel navigation method is presented for the cleaning robot in the unknown workspace. In order to do this, we propose a new map representation method and a complete coverage navigation method. First, we discuss a triangular cell map representation which makes the cleaning robot navigate with shorter path and increased flexibility than a rectangular cell map representation. Then we proposed a complete coverage navigation and map construction method which the cleaning robot can navigate the complete workspace although it has perfectly no information about environment. Finally, we evaluate the performance of our proposed triangular cell map comparing to that of the rectangular cell map via the existing ...

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Analysis of the TEM Cells Having arbitrary Rectangular Septum by Using Moment Method (모멘트법을 이용한 임의의 구형 내부도체를 갖는 TEM Cell의 특성 분석)

  • 윤재훈;최익권
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.15 no.11
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    • pp.898-908
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    • 1990
  • This paper applies the moment method to analyze the transverse electromagnetic(TEM) cell with an inner conductor (septum) of arbitrary rectangular shape and location by employing quast static approximation. The EM field and the characteristic impedance so obtained are shown to be in good agreement with the available data from the previously published papers about the typical TEM cell structure with center septum of zero thickness.

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Mixed Convection Heat Transfer in a Rectangular Enclosure with Various Outlets (좁은 환기구를 가진 사각공간에서의 혼합대류 열전달)

  • Lee, C.J.;Chung, H.S.;Kwon, S.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.2
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    • pp.207-216
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    • 1995
  • Flow and heat transfer characteristics of mixed convection heat transfer in a rectangular en-closure with various outlets are numerically investigated. The parameters considered here include Reynolds number, Grashof number and the position of outlet. The results show streamlines, isotherms, Nusselt numbers, velocity and temperature distributions. It has been shown that as Reynolds number increases, the size of cell decreases at Re$\leq$100 and increases at Re>100 for $Gr=10^4$. There is a minimum size of cells at Re=100, $Gr=10^4$. The maximum mean Nusselt number occurs at Re=400, $Gr=10^4$ and one right outlet. The mean Nusselt numbers can be formulated by the correlation equation $Nu=C{\cdot}Gr^a{\cdot}Re^b$.

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The study of mixed convection in a rectangular enclosure for indoor air control (실내공기 제어를 위한 사각공간내의 혼합대류에 관한 연구)

  • 이철재;정한식;권순석
    • Journal of Ocean Engineering and Technology
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    • v.10 no.4
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    • pp.109-117
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    • 1996
  • The numerical and experimental studies on the mixed convection of a rectangular enclosure for indoor air control has been studied numerically using the finite volume method and experimentally with holographic interferometry and Laser apparatus. The parameters studied here are Pr= 0.71, $30{\leq}Re{\leq}600$, $700{\leq}Gr{\leq}100000$ and the positions of an outlet. The results show streamlines, isothrems, velocity distributions and photograph of holographic interferometry and streamlines. It is found that the minimum cell occurs at Re=100, Gr=10000. The mean Nusselt numbers can be expressed by the correlation equation $Nu=C{\cdot}Gr^a$ $Re^b.$ The comparison of numerical and experimental results shows a good agreement.

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The Effect of Blank Holding Force on Thickness Variation in Simultaneous Sheet forming process with Circle and Rectangle Shape of AZ31B Magnesium Sheet (AZ31B 마그네슘 판재의 원형 및 사각형 동시변형 공정에서 블랭크 홀딩력이 두께변화에 미치는 영향)

  • Kwon, K.T.;Kang, S.B.;Kim, H.H.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.18 no.7
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    • pp.531-537
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    • 2009
  • The effect of blank holding force on thickness variation in simultaneous sheet forming with rectangular shape and circular has been demonstrated. Because has investigated an effect on formability of magnesium sheet, in this paper, the effect of punch radius on formability have been thinning, various crack phenomena and forming velocity. By simultaneously forming process with circular and rectangular shape, the data of simultaneously forming process with circular and rectangular shape will used to a part development such as notebook computer case, cell phone and bipolar plate of fuel cell.

Effective Longitudinal Shear Modulus of Continuous Fiber-Reinforced 2-Phase Composites (연속섬유가 보강된 2상 복합재료의 종방향 전단계수 해석)

  • Lee, Dong-Ju;Jeong, Tae-Hyeon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.9
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    • pp.2770-2781
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    • 1996
  • Longitudinal shear modulus of continuous fiber reinforced 2-phase composites is predicted by theoretical and numerical analysis methods. In this paper, circular, hexagonal and rectangular shapes of reinforced fiber are considered using unit cell concept. And fiber array is regular rectangular and hexagonal fiber arrangement. Longitudinal shear modulus is a function of fiber distribution pattern and fiber volume change. It is found that the rectangular array has a higher longitudinal shear modulus than the hexagonal one. Also, the rectangular fiber shape in lower fiber volume fraction and the circular fiber shape in higher fiber volume fraction show the higher longitudinal shear modulus. And it has been found that the theoretical and numerical predictions of the longitudinal shear modulus give a good agreement with the experimental data at lower fiber volume fraction. Both the distance and stress transfer between the fibers are discussed as the major determing factors.

STUDY OF THREE-DIMENSIONAL DETONATION WAVE STRUCTURES USING PARALLEL PROCESSING (병렬 처리를 이용한 3차원 데토네이션 파 구조 해석)

  • Cho D.R.;Choi J.Y.
    • 한국전산유체공학회:학술대회논문집
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    • pp.151-155
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    • 2005
  • Three-dimensional structures of unsteady detonation wave propagating through a square-shaped tube is studied using computational method and parallel processing. Inviscid fluid dynamics equations coupled with variable-${\gamma}$ formulation and simplified one-step Arrhenius chemical reaction model were analysed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Results in three dimension show the two unsteady detonation wave propagating mode, the Rectangular and diagonal mode of detonation wave instabilities. Two different modes of instability showed the same cell length but different cell width and the geometric similarities in smoked-foil record.

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NUMERICAL STUDY OF THREE-DIMENSIONAL DETONATION WAVES USING PARALLEL PROCESSING (병렬 처리를 이용한 3차원 테토네이션 파 수치해석)

  • Cho, D.R.;Choi, J.Y.
    • 한국연소학회:학술대회논문집
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    • pp.15-19
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    • 2005
  • Three-dimensional structures of unsteady detonation wave propagating through a square-shaped tube is studied using computational method and parallel processing. Inviscid fluid dynamics equations coupled with variable-${\gamma}$ formulation and simplified one-step Arrhenius chemical reaction model were analysed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Results in three dimension show the two unsteady detonation wave propagating mode, the Rectangular and diagonal mode of detonation wave instabilities. Two different modes of instability showed the same cell length but different cell width and the geometric similarities in smoked-foil record.

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