• Title/Summary/Keyword: Tex Visualization

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On the Characteristics of the Droplet Formation from an Inkjet Nozzle Driven by a Piezoelectric Actuator (피에조 구동형 잉크젯 노즐에서의 미세 액적 형성 특성)

  • Shin, Pyung-Ho;Sung, Jae-Yong;Lee, Suk-Jong
    • Journal of the Korean Society of Visualization
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    • v.6 no.1
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    • pp.47-52
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    • 2008
  • The present study has focused on the characteristics of droplet formation from an inkjet nozzle driven by a piezoelectric actuator. As an operating fluid, ethylene glycol was used and the physical properties of it such as viscosity, surface tension, contact angle and shear stress were measured. During the experiments, various temperatures and driving voltages are imposed on a capillary tube. These conditions result in a proper drive condition or an overdrive condition. In case of the proper drive condition, an image processing technique is applied to measure the diameter of a single free drop. As a result, the size of droplet is increased when the driving voltage is increased from 160 V to 190 V at 25$^{\circ}C$ In the overdrive condition where temperature or driving voltage becomes higher than the proper drive condition, satellites and the misdirected jets happen.

Comparison Study on Aerodynamic Performance and Wake Flow Field for a MW-Class Wind Turbine Model (대형 풍력터빈 모형의 공력 성능 및 후류 유동장에 대한 비교 연구)

  • Jeong, Duwon;Won, Young Soo;Kang, Seung-Hee
    • Journal of the Korean Society of Visualization
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    • v.17 no.2
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    • pp.32-38
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    • 2019
  • A comparison study between computational-fluid-dynamics simulation and wind tunnel test for a megawatt-class wind turbine is conducted. For the study, flow-field in wake, basic aerodynamic performance, and effect of the yaw error for a 1/86 scaled-down model of the NREL offshore 5 MW wind turbine are numerically calculated using commercial software "FloEFD" with $k-{\varepsilon}$ turbulence model. The computed results are compared to the wind tunnel test performed by the constant-velocity mode for the model. It is shown that discrepancy are found between the two results at lower tip-speed ratio and higher yaw angle, however, the velocity-defection distribution in the wake, the torque coefficient at moderated and high tip-speed ratios are in good agreement with the wind tunnel test.

Mechanoluminescence materials and their application

  • Xu, Chao-Nan
    • 한국정보디스플레이학회:학술대회논문집
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    • 2009.10a
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    • pp.286-287
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    • 2009
  • Elasticoluminescence(ESL) is a kind of mechanoluminescence(ML). ESL materials are novel functional materials that can convert elastic deformation energy into visible light directly. Utilizing the materials, novel sensing devices and various applications are now under development. These materials can allow direct viewing of stress distribution.

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Software development for the visualization of brain fiber tract by using 24-bit color coding in diffusion tensor image

  • Oh, Jung-Su;Song, In-Chan;Ik hwan Cho;Kim, Jong-Hyo;Chang, Kee-Hyun;Park, Kwang-Suk
    • Proceedings of the KSMRM Conference
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    • 2002.11a
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    • pp.133-133
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    • 2002
  • Purpose: The purpose of paper is to implement software to visualize brain fiber tract using a 24-bit color coding scheme and to test its feasibility. Materials and Methods: MR imaging was performed on GE 1.5 T Signa scanner. For diffusion tensor image, we used a single shot spin-echo EPI sequence with 7 non-colinear pulsed-field gradient directions: (x, y, z):(1,1,0),(-1,1,0),(1,0,1),(-1,0,1),(0,1,1),(0,1,-1) and without diffusion gradient. B-factor was 500 sec/$\textrm{mm}^2$. Acquisition parameters are as follows: TUTE=10000ms/99ms, FOV=240mm, matrix=128${\times}$128, slice thickness/gap=6mm/0mm, total slice number=30. Subjects consisted of 10 normal young volunteers (age:21∼26 yrs, 5 men, 5 women). All DTI images were smoothed with Gaussian kernel with the FWHM of 2 pixels. Color coding schemes for visualization of directional information was as follows. HSV(Hue, Saturation, Value) color system is appropriate for assigning RGB(Red, Green, and Blue) value for every different directions because of its volumetric directional expression. Each of HSV are assigned due to (r,$\theta$,${\Phi}$) in spherical coordinate. HSV calculated by this way can be transformed into RGB color system by general HSV to RGB conversion formula. Symmetry schemes: It is natural to code the antipodal direction to be same color(antipodal symmetry). So even with no symmetry scheme, the antipodal symmetry must be included. With no symmetry scheme, we can assign every different colors for every different orientation.(H =${\Phi}$, S=2$\theta$/$\pi$, V=λw, where λw is anisotropy). But that may assign very discontinuous color even between adjacent yokels. On the other hand, Full symmetry or absolute value scheme includes symmetry for 180$^{\circ}$ rotation about xy-plane of color coordinate (rotational symmetry) and for both hemisphere (mirror symmetry). In absolute value scheme, each of RGB value can be expressed as follows. R=λw|Vx|, G=λw|Vy|, B=λw|Vz|, where (Vx, Vy, Vz) is eigenvector corresponding to the largest eigenvalue of diffusion tensor. With applying full symmetry or absolute value scheme, we can get more continuous color coding at the expense of coding same color for symmetric direction. For better visualization of fiber tract directions, Gamma and brightness correction had done. All of these implementations were done on the IDL 5.4 platform.

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A Study on the Oil/Water Separation Efficiency of Laminated Plate Type Oily water Separator with Inclined Angle (경사각을 갖는 적층판식 유수분리기의 유수분리 효율에 관한 연구)

  • 한원희;김준효;최민선
    • Journal of Advanced Marine Engineering and Technology
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    • v.25 no.2
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    • pp.365-374
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    • 2001
  • Its a tendency to strengthen related international was as the importance on marine oil pollution recently becomes the issue. According to the regulation of IMO, oil discharge from ships is allowed under 15PPM only and oil filtering equipment is essential. Oily water separator of laminated plate type which is one of gravity type separator can be use as assistant equipment for the oil filtering system to meet the present IMO standard, because it fits well to process large amount of rich oil with high specific gravity. The purpose of this paper is to investigate an efficiency of oil/water separation with the characteristics of laminated plate arrangement. The analyse of oil contents for oil-water mixture were carried out in order to find an efficiency of oil/water separation and an experimental study was simultaneously carried out to investigate internal flow characteristics of separator by visualization method and PIV(Particle Image Velocimetry) measurement at three spaces of plates for 5, 10 and 15 mm with variation of inlet flow rates of $0.25m^3$/h and $0.5m^3$/h. The experimental results showed that the space of the plates acts a significant role in the separating process.

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Capillary-driven Rigiflex Lithography for Fabricating High Aspect-Ratio Polymer Nanostructures (모세관 리소그라피를 이용한 고종횡비 나노구조 형성법)

  • Jeong, Hoon-Eui;Lee, Sung-Hoon;Kim, Pil-Nam;Suh, Kahp-Y.
    • Journal of the Korean Society of Visualization
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    • v.5 no.1
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    • pp.3-8
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    • 2007
  • We present simple methods for fabricating high aspect-ratio polymer nanostructures on a solid substrate by rigiflex lithography with tailored capillarity and adhesive force. In the first method, a thin, thermoplastic polymer film was prepared by spin coating on a substrate and the temperature was raised above the polymer's glass transition temperature ($T_g$) while in conformal contact with a poly(urethane acrylate) (PUA) mold having nano-cavities. Consequently, capillarity forces the polymer film to rise into the void space of the mold, resulting in nanostructures with an aspect ratio of ${\sim}4$. In the second method, very high aspect-ratio (>20) nanohairs were fabricated by elongating the pre-formed nanostructures upon removal of the mold with the aid of tailored capillarity and adhesive force at the mold/polymer interface. Finally, these two methods were further used to fabricate micro/nano hierarchical structures by sequential application of the molding process for mimicking nature's functional surfaces such as a lotus leaf and gecko foot hairs.

Active Infrared Thermography for Visualizing Subsurface Micro Voids in an Epoxy Molding Compound

  • Yang, Jinyeol;Hwang, Soonkyu;Choi, Jaemook;Sohn, Hoon
    • Journal of the Korean Society for Nondestructive Testing
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    • v.37 no.2
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    • pp.106-114
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    • 2017
  • This paper presents an automated subsurface micro void detection technique based on pulsed infrared thermography for inspecting epoxy molding compounds (EMC) used in electronic device packaging. Subsurface micro voids are first detected and visualized by extracting a lock-in amplitude image from raw thermal images. Binary imaging follows to achieve better visualization of subsurface micro voids. A median filter is then applied for removing sparse noise components. The performance of the proposed technique is tested using 36 EMC samples, which have subsurface (below $150{\mu}m{\sim}300{\mu}m$ from the inspection surface) micro voids ($150{\mu}m{\sim}300{\mu}m$ in diameter). The experimental results show that the subsurface micro voids can be successfully detected without causing any damage to the EMC samples, making it suitable for automated online inspection.

The study on the effect of the solar radiation on thermal comfort and ventilation performance in room space (태양일사가 실내공간의 열적 쾌적성과 환기성능에 미치는 영향에 관한 연구)

  • Yeon, Seong Hyeon;Lee, Hyo Joon;Rhee, Gwang Hoon
    • Journal of the Korean Society of Visualization
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    • v.14 no.1
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    • pp.19-26
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    • 2016
  • Modern people spend much time at indoor space. So, People want to make better indoor air condition. But the facade of building is made of glass to be seen urbanely, the effect of solar radiation makes indoor environment worse. This study designs an open space affected by solar radiation with 4-way cassette air-conditioner. Using numerical simulation, this paper investigates thermal comfort and ventilation performance with discharge angles $30^{\circ}$ and $45^{\circ}$. To study thermal comfort, this paper studies distribution of velocity, temperature and effective draft temperature. Also, this paper introduces concept of air age to study ventilation performance. The flow influenced by solar radiation determines thermal comfort and ventilation performance in room space. This study shows that discharge angle of 45 degree has better thermal comfort and ventilation performance than that of 30 degree.

The Atomization Mechanism and Spray Characteristics of Drum Type Rotary Atomizer (드럼형 회전연료노즐의 미립화 기구 및 분무특성 연구)

  • Lee, Dong-Hun;Choi, Hyun-Kyung;Choi, Seong-Man;You, Gyung-Won;Huh, Hwan-Il
    • Journal of the Korean Society of Propulsion Engineers
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    • v.12 no.2
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    • pp.57-65
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    • 2008
  • The atomization phenomena and spray characteristics of drum type rotary atomizer using centrifugal force from high rotational speed of gas turbine engine shaft were studied through rotary atomizer modeling analysis and experimental method. A test rig for rotary atomization that has range of $5,000{\sim}40,000\;rpm$ was used to make similarity for high speed rotating shaft. Spray visualization methodology and Phase Doppler Anemometry were also used to investigate the atomization mechanism and spray characteristics. We found that the rotating fuel spray has unique breakup process and we have to make breakup point earlier through increasing rotating speed to improve atomization performance.