• Title/Summary/Keyword: Phase Effect

Search Result 7,751, Processing Time 0.039 seconds

Effect of Phase Error on the Lateral Resolution of Reconstruction Image in Incoherent Triangular Holography (인코히어런트 삼각 홀로그래피에서 위상오차가 횡축방향의 해상도에 미치는 영향에 관한 연구)

  • Kim, Soo-Gil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.27 no.11
    • /
    • pp.1-6
    • /
    • 2013
  • It is introduced the phase error sources of a incoherent hologram in incoherent triangular holography and derived the reconstruction image of point-source including the phase error in the lateral direction. From the reconstruction image of point-source, we analyzed the effect of phase error on the lateral resolution. When the phase retardation errors and azimuth angle error of a wave plate and a polarizer range from 0 to $2{\pi}/15$, the normalized intensities of reconstructed images are down by about 0.1% and 2.3%, respectively.

Effect of Impurities in Grain Boundary Phases on Wear Behavior of $Si_3N_4$ (질화규소의 입계상에 존재하는 불순물이 마모에 미치는 영향)

  • 오윤석;임대순;이경호
    • Journal of the Korean Ceramic Society
    • /
    • v.33 no.3
    • /
    • pp.277-284
    • /
    • 1996
  • The water test results indicated that the impurities had detrimetal effect on the wear resistance of silicon nitride and the effects were getting severe as the temperature increased. Especially when Ca existed as an impurity the detrimental effects was the most severe. These results were resulted from the fact that impurities lowered the mechanical properties of the grain boundary phase of silicon nitride. The wear test results of glass/glass-ceramic specimens having a similar composition to the grain boundary phase of silicon nitride revea-led that the specimen containing CaO showed the lowest wear resistance. The existence of Fe and Ca at the grain boundary phase assisted forming a grain boundary phase with relatively low refractoriness. Therefore at a given wear condition the removal of deformed layer would be easier. The results showed that the glass phases could be modified by heat-treatment and this modification improved tribological characteristics of the silicon nitride.

  • PDF

Effect of Silica Addition on Phase Transformation Characteristics of Heat-Treated Combustion-Synthesized TiO2 Nanoparticles (실리카가 첨가된 연소합성 TiO2 나노입자의 열처리에 따른 상변환 특성)

  • Kim, Min-Su;Lee, Gyo-Woo
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.33 no.3
    • /
    • pp.186-193
    • /
    • 2009
  • In this article, the effect of silica addition on the phase transformation characteristics of $TiO_2$ nanoparticles synthesized by using an $O_2$-enriched coflow, hydrogen, diffusion flame was investigated. TTIP(titanium tetra-isopropoxide) and TEOS(tetraethyl-orthosilicate) were used as precursors for $TiO_2$ and $SiO_2$ nanoparticles, respectively. Based on the results from TEM and XRD analysis, it is believed that the silica addition on the flame synthesis of $TiO_2$ nanoparticles reduces the particle size distribution and raises the temperature of the phase transition from anatase to rutile. But the reduced sizes of the synthesized particles due to the silica addition made the sintering and phase transformation of particles more easily.

PERFORMANCE ANALYSIS OF NREL PHASE VI WIND TURBINES UNDER VARIOUS SCALE CONDITIONS (스케일 변화에 따른 NREL PHASE VI 풍력터빈의 성능해석)

  • Park, Y.M.;Chang, B.H.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2006.10a
    • /
    • pp.155-158
    • /
    • 2006
  • In the present paper, the scale effects of two-dimensional airfoil and three-dimensional wind turbine were investigated by using FLUENT software. For two dimensional analysis, flow around S809 airfoil with various Reynolds No. and Mach No. conditions were simulated. For three dimensional analysis, scaled NREL Phase VI wind turbine models from 6% to 1,600% were simulated under the same tip speed ratio condition. Finally, aerodynamic comparisons between two-dimensional flow and three dimensional wind turbine flow are made for the feasibility study of scale effect corrections. Currently, KARI(Korea Aerospace Research Institute) is preparing for the wind tunnel test of 12% NREL Phase VI wind turbine and the performance analysis of the scaled NREL wind turbine model will be validated by the wind tunnel test.

  • PDF

Experimental and Numerical Study on Characteristics of Air-assisted Spray and Spray Flames (2유체 분무의 연소특성에 관한 실험 및 수치 해석적 연구)

  • Kim, Dong-Il;Oh, Sang-Huen
    • Journal of the Korean Society of Combustion
    • /
    • v.3 no.2
    • /
    • pp.51-63
    • /
    • 1998
  • Air-assisted atomizer flames are investigated numerically to study spray structures in nonburning and burning conditions based on experimental data. A PDA is used to measure droplet size, velocity, and number density for both nonburning and burning spray. Computations utilize time-averaged gas-phase equations and $k-{\varepsilon}$ turbulence model for simplicity. The major features of the liquid-phase model are that a SSF approach is used to represent the effect of gas-phase turbulence on droplet trajectories and vaporization, an infinite-diffusion model is employed to represent the transient liquid-phase process. Computation and experiment results show that the droplet acceleration and evaporation proceed quickly in near the atomizer, characterizing high number densities and a strong convective effect. The primary combustion zone, however, is dorminated by the gas phase reaction and exhibits a sheath combustion.

  • PDF

Effect of Phase Transformation and Grain-size Variation on the Dry Sliding Wear of Hot-pressed Cobalt

  • Kim, Yong-Suk;Lee, Jong-Eun;Kang, Suk-Ha;Kim, Tai-Woong
    • Proceedings of the Korean Powder Metallurgy Institute Conference
    • /
    • 2006.09b
    • /
    • pp.879-880
    • /
    • 2006
  • Effect of phase transformation and grain-size variation of hot-pressed cobalt on its dry sliding wear was investigated. The sliding wear test was carried out against glass (83% $SiO_2$) beads at 100N load using a pin-on-disk wear tester. Worn surfaces, cross sections, and wear debris were examined by an SEM. Phases of the specimen and wear debris were identified by an XRD. Thermal transformation of the cobalt from the hcp $\varepsilon$ phase to the $\gamma$ (fcc) phase during the wear was detected, which was deduced as the wear mechanism of the sintered cobalt.

  • PDF

Numerical Simulation for an Air-Solid Two-Phase Flow in a Vertical Pipe (기체 흐름에 고체입자가 섞인 파이프 내의 이상유동에 대한 수치 해석)

  • Pak S. I.;Chang K. S.
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2002.10a
    • /
    • pp.41-46
    • /
    • 2002
  • A numerical simulation was made to determine the motion of particles in the fluid. The simulation is based on the Eulerian-Lagrangian method. The fluid motion was solved using a PISO-based finite-element method and a $\kappa-\epsilon$ model of turbulence. In the Lagrangian method for the solid phase, the trajectories of particles are calculated by integrating the equations of motion of a single Particle, and the collision between particles are taken into account. The influence of particles on the fluid phase is taken into account by introducing source terms in the Eulerian equations govering the fluid flow. It is known as the particle-source-in-cell (PSIC) method. Also, the turbulent effect in the particles and fluid notion is considered. The numerical results were compared with the experiment for a two-phase flow in a vertical pipe.

  • PDF

Phase Peak Ambiguity According to Illumination in White-Light Phase-Shifting Interferometry (백색광 간섭계의 위상 정점 알고리즘에서 조명에 따른 위상 정점 모호성에 관한 연구)

  • Kim, Gee-Hong;Lee, Hyung-Seok
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.25 no.1
    • /
    • pp.85-91
    • /
    • 2008
  • White light scanning interferometry has gotten a firm position in 3D surface profile measuring field. Recently, the LCD industry gave a chance for this technology to enter into real industry fields. It is known that white-light phase-shifting algorithm give a best resolution compare to other algorithms, but there are some problems to be resolved. One of them is 300nm jump in height profile, called bat-wing effect. The main reason of this problem is an ambiguity of phase-peak detection algorithm, and some solution has been proposed, but it didn't work perfectly. In this paper, I will show the cases when these effects are occurred, and these height discrepancies will be almost disappeared when broad-band illuminators are used.

Numerical Simulation of Two-Phase Flow field and Performance Prediction for Solid Rocket Motor Nozzle

  • Wahab, Shafqat;Kan, Xie;Yu, Liu
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2008.03a
    • /
    • pp.275-282
    • /
    • 2008
  • This paper presents numerical investigation of multi-phase flow in solid rocket motor nozzle and effect of multi-phases on the performance prediction of the Solid Rocket Motor. Aluminized propellants are frequently used in solid rocket motors to increase specific impulse. An Eulerian-Lagrangian description has been used to analyze the motion of the micrometer sized and discrete phase that consist of the larger particulates present in the Solid Rocket Motor. Uniform particles diameters and Rosin-Rammler diameter distribution method has been used for the simulation of different burning of aluminum droplets generating aluminum oxide smokes. Roe-FDS scheme has been used to simulate the effects of the multi-phase flow. The results obtained show the sensitivity of this distribution to the nozzle flow dynamics, primarily at the nozzle inlet and exit. The analysis also provides effect of two phases on performance prediction of Solid Rocket Motor.

  • PDF

Effect of gravity on a micropolar thermoelastic medium with voids under three-phase-lag model

  • Alharbi, Amnah M.;Othman, Mohamed I.A.;Al-Autabi, Al-Anoud M.Kh.
    • Structural Engineering and Mechanics
    • /
    • v.76 no.5
    • /
    • pp.579-590
    • /
    • 2020
  • This paper's objective is to investigate the effect of gravity on a micropolar thermoelastic medium with voids. The problem is assessed according to the three-phase-lag model. An analysis of the resulting non-dimensional displacement, temperature variation, and internal stress of the study material is carried out and presented graphically. The non-dimensional displacement, temperature, micro-rotation, the change in the volume fraction field and stress of the material are obtained and illustrated graphically. Comparisons are made with the results predicted by different theories for different values of gravity, the phase-lag of the heat flux and the phase-lag of the temperature gradient. The numerical results reveal that gravity and relaxation times have a significant influence on the distribution of the field quantities. Some notable insights of interest are deduced from the investigation.