• 제목/요약/키워드: H-plane

검색결과 1,299건 처리시간 0.029초

Influences of seepage force and out-of-plane stress on cavity contracting and tunnel opening

  • Zou, Jin-Feng;Chen, Kai-Fu;Pan, Qiu-Jing
    • Geomechanics and Engineering
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    • 제13권6호
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    • pp.907-928
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    • 2017
  • The effects of seepage force and out-of-plane stress on cavity contracting and tunnel opening was investigated in this study. The generalized Hoek-Brown (H-B) failure criterion and non-associated flow rule were adopted. Because of the complex solution of pore pressure in an arbitrary direction, only the pore pressure through the radial direction was assumed in this paper. In order to investigate the effect of out-of-plane stress and seepage force on the cavity contraction and circular tunnel opening, three cases of the out-of-plane stress being the minor, intermediate, or major principal stress are assumed separately. A method of plane strain problem is adopted to obtain the stress and strain for cavity contracting and circular tunnel opening for three cases, respectively, that incorporated the effects of seepage force. The proposed solutions were validated by the published results and the correction is verified. Several cases were analyzed, and parameter studies were conducted to highlight the effects of seepage force, H-B constants, and out-of-plane stress on stress, displacement, and plastic radius with the numerical method. The proposed method may be used to address the complex problems of cavity contraction and tunnel opening in rock mass.

관 유동과 Blasius 유동에서 가장 불안정한 교란에 관하여 (On the Most Unstable Disturbance of Channel Flows and Blasius Flow)

  • 최상규;정명균
    • 대한기계학회논문집B
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    • 제27권6호
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    • pp.766-772
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    • 2003
  • The pseudospectral method for stability analysis was used to find the most influential disturbance mode for transition of plane channel flows and Blasius flow at their critical Reynolds numbers. A number of various oblique disturbance waves were investigated for their pseudospectra and resolvent norm contours in each flow, and an exhaustive search method was employed to find the disturbing waves to which the flows become most unstable. In plane Poiseuille flow an oblique disturbance with a wavelength of 3.59h (where h is the half channel width) at an angle $28.7^{\circ}$ was found to be the most influential for the flow transition to turbulence, and in plane Couette flow it is an oblique wave with a wavelength of 3.49h at an angle of $19.4^{\circ}$. But in Blasius flow it was found that the most influential mode is a normal wave with a wavelength of $3.44{\delta}_{999}$. These results imply that the most influential disturbance mode is closely related to the fundamental acoustic wave with a certain shear sheltering in the respective flow geometry.

Heat Treatment of Carbonized Photoresist Mask with Ammonia for Epitaxial Lateral Overgrowth of a-plane GaN on R-plane Sapphire

  • Kim, Dae-sik;Kwon, Jun-hyuck;Jhin, Junggeun;Byun, Dongjin
    • 한국재료학회지
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    • 제28권4호
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    • pp.208-213
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    • 2018
  • Epitaxial ($11{\bar{2}}0$) a-plane GaN films were grown on a ($1{\bar{1}}02$) R-plane sapphire substrate with photoresist (PR) masks using metal organic chemical vapor deposition (MOCVD). The PR mask with striped patterns was prepared using an ex-situ lithography process, whereas carbonization and heat treatment of the PR mask were carried out using an in-situ MOCVD. The heat treatment of the PR mask was continuously conducted in ambient $H_2/NH_3$ mixture gas at $1140^{\circ}C$ after carbonization by the pyrolysis in ambient $H_2$ at $1100^{\circ}C$. As the time of the heat treatment progressed, the striped patterns of the carbonized PR mask shrank. The heat treatment of the carbonized PR mask facilitated epitaxial lateral overgrowth (ELO) of a-plane GaN films without carbon contamination on the R-plane sapphire substrate. Thhe surface morphology of a-plane GaN films was investigated by scanning electron microscopy and atomic force microscopy. The structural characteristics of a-plane GaN films on an R-plane sapphire substrate were evaluated by ${\omega}-2{\theta}$ high-resolution X-ray diffraction. The a-plane GaN films were characterized by X-ray photoelectron spectroscopy (XPS) to determine carbon contamination from carbonized PR masks in the GaN film bulk. After $Ar^+$ ion etching, XPS spectra indicated that carbon contamination exists only in the surface region. Finally, the heat treatment of carbonized PR masks was used to grow high-quality a-plane GaN films without carbon contamination. This approach showed the promising potential of the ELO process by using a PR mask.

반비례적으로 변하는 저항율을 갖는 반평면에 의한 H 분극산란 (H-Polarized Scattering by an Inversely Tapered Resistive Half Plane)

  • 양승인;나정웅
    • 대한전자공학회논문지
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    • 제26권7호
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    • pp.1-7
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    • 1989
  • 가장자리로 부터 역비례로 저항률이 변하는 반평면에 H분극 평면파가 입사되는 경우, 산란파를 Kontorovich-Lebedev 변환을 이용해서 정확한 적분식으로 얻었으며, 이로부터 모든 각도에서 쓸 수 있는 균일 근사식 및 계산된 산란파를 광선적(光線的)으로 해석할 수 있도록 해주는 비균일 근사식도 구했다. 저항율의 상수 여러 값에 대하여 가장자리 회절 패턴을 보였다. 결과들은 물리적으로 타당함을 알 수 있었다.

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팁간극이 고선회각 터빈 동익 평면팁 표면에서의 열전달에 미치는 영향 (Effect of Tip Clearance Height on Heat Transfer Characteristics on the Plane Tip Surface of a High-Turning Turbine Rotor Blade)

  • 문현석;이상우
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2005년도 연구개발 발표회 논문집
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    • pp.173-177
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    • 2005
  • The heat/mass transfer characteristics on the plane tip surface of a high-turning first-stage turbine rotor blade has been investigated by employing the naphthalene sublimation technique. The heat/mass transfer coefficient is measured for four tip clearance height-to-chord ratios of h/c = 1.0%, 2.0%, 3.0%, and 4% at the Reynolds number of $2.09{\times}105$. The result shows that at lower h/c, there exists a strong flow separation/re-attachment process, which results in severe thermal load along the pressure-side comer. As h/c increases, the re-attachment is occurred further downstream of the pressure-side comer with lower thermal load. At higher h/c, a pair of vortices on the tip surface near the leading edge are found along the pressure-side and suction-side comers, and the pressure-side tip vortex have significant influence even on the mid-chord local heat transfer.

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X타 수중함의 유도·제어시스템 설계 (Design of Guidance and Control System for X-plane Submarine)

  • 박종용;유영준;전명준;윤현규
    • 대한조선학회논문집
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    • 제59권5호
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    • pp.306-313
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    • 2022
  • Most submarines use the cross-plane, which is convenient and inexpensive, but the number of submarines equipped with an X-plane is increasing recently. This study focuses on designing the control system of the X-plane submarine with various control methods and analyzing the effect of each controller. First, a maneuvering simulation environment for a subjected submarine is established. The dynamics and the operating range of control surfaces are considered. Second, a depth and heading control system of the submarine, which can be divided into three parts, is designed: guidance, controller, and control allocation. The guidance system generates a smooth desired depth and heading. The controller is designed using Proportional-Integral-Differential (PID), Linear Quadratic Regulator (LQR), and H-infinity (H∞) control methods. A linear control allocation method is used to distribute control moment calculated by the controller to the control surfaces. Finally, the designed control system is applied to a subjected X-plane submarine, and a depth and heading control simulations are performed. Each control method is compared and analyzed under various simulation conditions.

Local Laser Annealing in Exchange-Biased Films with Out-of-Plane and In-Plane Magnetic Anisotropy

  • Choi, S.D.;Kim, S.W.;Jin, D.H.;Yun, D.K.;Lee, M.S.;Ahn, J.H.;Joo, H.W.;Lee, K.A.;Lee, S.S.;Hwang, D.G.
    • Journal of Magnetics
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    • 제11권2호
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    • pp.66-69
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    • 2006
  • Local magnetization reversal in the exchange-biased NiFe/FeMn and $[Pd/Co]_5/FeMn$ multilayers with in-plane and out-of-plane magnetic anisotropy was achieved by using laser annealing. The local annealed NiFe/FeMn film under the opposite magnetic field shows a magnetoresistance (MR) curve having two symmetric peaks at the positive and negative exchange biasing field (${\pm}H_{ex}$). The intensity of the nucleated MR peak rises as the exposed area extends during the laser annealing process, and the peak disappears under the reverse magnetic field. In the case of [Pd/Co]/FeMn films, the local magnetization reversal increased gradually as the laser power increases. The locally reversed magnetization was restored under the opposite magnetic field.