• Title/Summary/Keyword: roe

Search Result 475, Processing Time 0.03 seconds

A Study on Selection of Strategic Export Items in Fisheries Sector for Korea-China FTA (한·중 FTA 대응 수산분야 전략적 수출품종 선정에 관한 연구)

  • Hwang, Su-Yeon;Kim, Do-Hoon
    • Journal of Fisheries and Marine Sciences Education
    • /
    • v.27 no.1
    • /
    • pp.170-183
    • /
    • 2015
  • The objectives of this study is to analyze the competitiveness of fisheries trade between Korea and China, and to estimate strategic seafood export products for Korea-China FTA in fisheries sector. The results of analyses indicate that Korea has comparative advantages in export items such as spanish mackerel, flatfish, cod, roe in frozen fish(0303), and squid, sea cucumber, oyster in molluscs(0307). In addition, tuna in prepared or preserved fish(1604), sea cucumber in crustacean, molluscs and other aquatic invertebrates(1605) have comparative advantage in exporting to China.

Numerical Prediction of Unsteady Flows through Whole Nozzle-Rotor Cascade Channels with Partial Admission

  • Sasao, Yasuhiro;Monma, Kazuhiro;Tanuma, Tadashi;Yamamoto, Satoru
    • International Journal of Fluid Machinery and Systems
    • /
    • v.2 no.3
    • /
    • pp.248-253
    • /
    • 2009
  • This paper presents a numerical study for unsteady flows in a high-pressure steam turbine with a partial admission stage. Compressible Navier-Stokes equations are solved by the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe's approximate Riemann solver, and the LU-SGS scheme. The SST-model is also solved for evaluating the eddy-viscosity. The unsteady two-dimensional flows through whole nozzle-rotor cascade channels considering a partial admission are numerically investigated. 108 nozzle passages with two blockages and 60 rotor passages are simultaneously calculated. The influence of the flange in the nozzle box to the lift of rotors is predicted. Also the efficiency of the partial admission stage changing the number of blockages and the number of nozzles is parametrically predicted.

Flexure hinge mechanism having amplified rectilinear motion for confocal scanning microscopy using optical section

  • Kwon, Oh-Kyu;Park, Poo-Gyeon
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 2001.10a
    • /
    • pp.162.6-162
    • /
    • 2001
  • Confocal scanning microscopy (CSM) is an important instrument in a wide variety of imaging applications because of its ability to provide three-dimensional images of thick, volume specimens. The mechanism for two-dimensional beam scanning and optical sectioning has an important roe in CSM as the three-dimensional profiler. This optical sectioning property arises from the use of a point detector, which serves to attenuate the signals from out-of-focus. The intensity profile for the open loop scanning should be matched with its response for the standard. The non-linearity can be minimized with the optical sectioning or the optical probe of the closed loop control. This paper shows the mathematical expression of the light such as the extinction curve in the optical fields of system using AO deflector, the axial/lateral response experimentally when the error sources change, and the methods of optical sectioning. Thorough design of optical sectioner is crucial to the success of CSM in the field ...

  • PDF

Implicit Incompressible flow solver on Unstructured Hybrid grids (비구조 혼합 격자에서 내재적 방법을 이용한 비압축성 유동해석)

  • Kim J.;Kim Y.M;Maeng J.S
    • 한국전산유체공학회:학술대회논문집
    • /
    • 1998.11a
    • /
    • pp.48-54
    • /
    • 1998
  • Three-dimensional incompressible Navier-Stokes equations have been solved by the node-centered finite volume method with unstructured hybrid grids. The pressure-velocity coupling is handled by the artificial compressibility algorithm and convective fluxes are obtained by Roe's flux difference splitting scheme with linear reconstruction of the solutions. Euler implicit method is used for time-integration. The viscous terms are discretised in a manner to handle any kind of grids such as tetrahedra, prisms, pyramids, hexahedra, or mixed-element grid. The numerical efficiency and accuracy of the present method is critically evaluated for several example problems.

  • PDF

Calculation of Turbulent Flows Using an Implicit Scheme on Two-Dimensional Unstructured Meshes (2차원 비정렬 격자에서의 내재적 기법을 이용한 난류 유동 재산)

  • Kang Hee Jung;Kwon Oh Joon
    • Journal of computational fluids engineering
    • /
    • v.2 no.2
    • /
    • pp.26-34
    • /
    • 1997
  • An implicit viscous turbulent flow solver is developed for two-dimensional geon unstructured triangular meshes. The flux terms are discretized based on a cell-centered formulation with the Roe's flux-difference splitting. The solution is advanced in time us backward-Euler time-stepping scheme. At each time step, the linear system of equation approximately solved wi th the Gauss-Seidel relaxation scheme. The effect of turbulence is with a standard k-ε two-equation model which is solved separately from the mean flow equation the same backward-Euler time integration scheme. The triangular meshes are generated advancing-front/layer technique. Validations are made for flows over the NACA 0012 airfoil. Douglas 3-element airfoil. Good agreements are obtained between the numerical result experiment.

  • PDF

Numerical Analysis of Aerodynamic Performance for Tilt Rotor Aircraft in Cruise Mode Using Chimaera Grid Method (겹침격자 기법을 이용한 틸트로터의 순항모드에 대한 공력성능 수치해석)

  • Ko S. H.;Ahn S. W.;Kim B. S.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2004.10a
    • /
    • pp.87-90
    • /
    • 2004
  • A numerical analysis was made for the unsteady flow fields of rotor system of a Tilt-Rotor aircraft in cruise mode. The Reynolds-averaged thin-layer Navier-Stokes equations were discretized by Roe's upwind differencing scheme and integrated in time by the LU-SGS algorithm. The computational domain of the rotor system was constructed by six multi-block Chimera grids. Simulated unsteady flow fields of rotating blades were studied in several different view points.

  • PDF

STUDY ON FLUX FUNCTIONS FOR THE EULER EQUATIONS (Euler 방정식의 Flux Function 특성 비교 연구)

  • Chae, E.J.;Lee, S.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2006.10a
    • /
    • pp.36-40
    • /
    • 2006
  • A comparative study on flux functions for the 2-dimensional Euler equations has been conducted. Explicit 4-stage Runge-Kutta method is used to integrate the equations. Flux functions used in the study are Steger-Warming's, van Leer's. Godunov's, Osher's(physical order and natural order), Roe's, HILE, AUSM, AUSM+ and AUSMPW+. The performance of MUSCL limiters and MLP limiters in conjunction with flux functions are compared extensively for steady and unsteady problems.

  • PDF

Numerical Visualization of the Shock Wave System Discharged from the Exits of Two-Parallel Ducts (두 평행한 관 출구로부터 방출되는 충격파시스템의 수치해석적 가시화)

  • Jung Sung Jae;Kweon Yong Hun;Kim Heuy Dong;Kang Chang Soo
    • 한국가시화정보학회:학술대회논문집
    • /
    • 2004.11a
    • /
    • pp.72-75
    • /
    • 2004
  • The present study describes a computational work to investigate detailed behaviors of the twin shock waves discharged from the exits of two-parallel ducts. In computations, the Yee-Roe-Davis's TVD scheme was used to solve the unsteady, three-dimensional, inviscid, compressible, Euler equations. The distance between two ducts is varied and the Mach number of the incident shock wave is changed below 2.0. The results obtained show that on the symmetric axis between two-parallel ducts, the maximum pressure achieved by the merge of twin shock waves and its location strongly depend upon the distance between two-parallel ducts and the Mach number of the incident shock wave. It is also found that the twin shock waves discharged from the exits of two-parallel ducts leads to the complicated flow fields, such as Mach stem, spherical waves, and vertical structures.

  • PDF

Pilot-Scale Testing of a Vibrating Electrostatic Separator for Fly Ash Decarbonization

  • Yoon, Roe-Hoan;Eric Yan;Han, Oh-Hyung;Park, Byung-Wook
    • Proceedings of the IEEK Conference
    • /
    • 2001.10a
    • /
    • pp.644-649
    • /
    • 2001
  • A new electrostatic separator has been developed for the removal of unburned carbon from fly ash. In this separator, a flowing film of fly ash is created on the surface of a vibrating electrode. Conducting particles such as unburned carbon acquire electrostatic charges and jump out of the flowing film so that they can be removed from the non-conducting fly ash particles moving forward. The new separator has been tested successfully using a pilot-scale test unit at 0.5 tons/hr capacity. Based on the successful test results, a larger unit is being constructed at the present time.

  • PDF

Sol-Gel Synthesis and Transport Properties of $La_{2/3}Sr_{1/3}Mn_{0.99}{^{57}}Fe_{0.01}O_3$Granular Thin Films

  • Shim, In-Bo;Kim, Sung-Baek;Ahn, Geun-Young;Yun, Sung-Roe;Cho, Young-Suk;Kim, Chul-Sung
    • Journal of Magnetics
    • /
    • v.6 no.1
    • /
    • pp.1-4
    • /
    • 2001
  • We have used acetic acids ethanol and distilled water as a solvent to synthesize $La_{2/3}Sr_{1/3}Mn_{0.99}{^{57}}Fe_{0.01}O_3$(LSMFO) precursor. Crack-free LSMFO granular polycrystalline thin films have been deposited on thermally oxidized silicon substrates by spin coaling. The dependence of crystallization, surface morphology, magnetic and transport properties on annealing temperature was investigated. With increasing annealing temperature, the metal-semiconductor (insulator) transition temperature and the magnetic moment decrease while the resistivity increases. The lattice constants remain almost unchanged. For LSMFO thin films, spin-dependent interfacial tunneling and/or scattering magnetoresistance were observed. Our results indicate that the annealing temperature is very important in determining the intrinsic and extrinsic magnetotransport properties.

  • PDF