• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.4
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• pp.82-87
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• 2003

Flow angle with Swirl in a horizontal circular tube and a cylindrical annuli were experimentally studied for its visualization. This present investigation deals with flow angle, flow visualization studies and vortex core by using oil smoke and a hot wire anemometer for Re = 40,000 and 50000 at X/D = 41, 59 and 71 in a horizontal circular tube. In the swirl air flow, a vortex core was formed at high swirl intensity along the test tube. The flow angle and the vortex core depended on the swirl intensity along the test tube. The results of flow angles with swirl measured by flow visualization and hot wire reasonably agree with those of Sparrow One of the primary objectives of this research was to measure the flow angle with swirl in a cylindrical annuli along the test tube for different Reynolds numbers. The Reynolds number for these measurements ranged from 60,000 to 100,000 with L/D = a to 4.

• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.44-50
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• 2006

A visualization study on the boundary layer and near-wake of an NACA 0012 airfoil was con-ducted in order to investigate the influence of boundary layer behavior on the near-wake at low Reynolds numbers. The present study is investigated at static angles of attack ${\alpha}=0^{\circ},\;3^{\circ},\;6^{\circ}$ and $Re=2.3{\times}10^4,\;3.3{\times}10^4,\;4.8{\times}10^4$ by using a smoke-wire technique. The results of this study show that the laminar boundary layer on the airfoil surface is attached to the surface at ${\alpha}=0^{\circ}$, and that laminar separation of boundary layer on the airfoil surface occurs at ${\alpha}=3^{\circ}$. Furthermore, reattachment of the boundary layer occurs in the case of ${\alpha}=6^{\circ}$. In the current study, the location of the laminar separation point moves upstream as the Reynolds number and the angle of attack increase.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.497-498
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• 2018

In the fire scene, it is difficult to see 1m ahead because of power failure, smoke and toxic gas, even with thermal imaging camera and Xenon searchlight. Analysis of the smoke particles in the fire scene shows that even if the smoke is $5{\mu}m$ or less in wavelength, it is difficult to obtain a front view when using a conventional thermal imaging camera if the visual distance exceeds 1 meter. In the case of black smoke with a particle wavelength of $5{\mu}m$ or more, a space permeation sensor technology using various sensors other than a single sensor is required because chemical materials, gas, and water molecules are mixed. Firefighters need a smoke detection technology for smoke detection and spatial information visualization for forward safety view.In this paper, we design the interface of the information processing system with 32bit CPU core and peripheral circuit. We also implemented and simulated the interface with Lidar sensor. Through this, we provide interface that can implement information processing system of human enhancement fire helmet in the future.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.43-54
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• 2004

A visualization study was carried out to investigate the effects of phase difference qualitatively by examining wake pattern on the phase difference of a dragonfly type wing model. The model was built with scaled-up, flapping wings composed of a paired wing with fore- and hind-wings in tandem that mimick the wing form of a dragonfly. The present study was conducted by using the smoke-wire technique and an electronic device below the tandem wings was mounted to find the exact wing position angles. Uncertainties in wing position angle are about $\pm$$1.0^{\cire}$ and instantaneous wing positional angle varies from $-16.5^{\cire}$ to $+22.8^{\cire}$. The tests were made at phase differences between the fore-wing and hind-wing at $0^{\cire}$, $90^{\cire}$, $180^{\cire}$ and $270^{\cire}$. The results show that Karman vortex structures were produced at phase differences of $90^{\cire}$, $180^{\cire}$ and $270^{\cire}$, but Karman vortex structures were not observed at the phase difference of $0^{\cire}$.

• Journal of the Korean Society of Visualization
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• v.7 no.2
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• pp.28-34
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• 2010

Two turbulent jet with different sinusoidal nozzle exit configurations of in-phase and $180^{\circ}$ out-of-phase were investigated experimentally using a smoke-wire method and a hot-wire anemometry. Mean velocity and turbulence intensity were measured at several downstream locations under $Re_D\;=\;5000$. For the case of in-phase nozzle configuration, the length of potential core exhibits negligible difference with respect to the transverse locations (0, $\lambda/4$ and $\lambda/2$), similar to that of a plane jet. On the other hand, a maximum difference of 30% in the potential-core length occurs for the $180^{\circ}$ out-of-phase configuration. The spatial distributions of turbulence intensities also show significant difference for the nozzle of $180^{\circ}$ out-of-phase, whereas non-symmetric distribution is observed in the near-exit region(x/D = 1) for the in-phase sinusoidal nozzle jet. Compared to a slit planc jet, the sinusoidal nozzle jets seem to suppress the velocity deficit as the flow goes downstream. The sinusoidal nozzle jet was found to decrease turbulent intensity dramatically. The flow visualization results show that the flow characteristics of the sinusoidal nozzle jet are quite different from those of the slit plane jet.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.67-70
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• 2002

In the present study a pre/post-processor program has been developed to be used with a general CFD code. This program is capable of performing the basic functions of the pre/post-processing, which include mesh generation and post processing plots. Also through perspective projection, this program can be used to check the quality of generated mesh by moving around inside the mesh. The smoke visualization can be also performed with the present program to visualize the smoke behavior in the case of fire simulation. The examples of the program execution are given in paper.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1154-1160
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• 2005

A panoramic-PIV system has been constructed for the analysis of the airflows in a room. Smoke is used as seeding particles and are visualized by a pulsed laser (Nd-Yag, 120 mJ). Panoramic images have been obtained by an image composition process using the two images obtained by the two cameras $(1k\times1k)$ that are viewing the wide measurement areas. Velocity vector fields have been obtained by the grey-level cross-correlation PIV method. Three room models $(L{\times}W{\times}H[mm^3],\;500\times500\times250,\;350\times350\times175,\;250\times250\times125)$ have been tested. The experimental results have proven that the constructed panoramic-PIV system can be used as a useful tool for analyzing the airflow characteristics in the room models.

• Fire Science and Engineering
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• v.15 no.1
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• pp.1-6
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• 2001

In this study, reduced-scale experiments were conducted to understand smoke movements in tunnel fires with the natural ventilation. The 1/20 scale experiments were conducted under the Froude scaling since the smoke movement in tunnels is governed by buoyancy force. Three cases of experiments, in which a natural vent location varied from 1 m, 2 m and 3 m from the fire source symmetrically, were conducted in order to evaluate the effect of the position of ventilation systems on smoke movement. In case of a poo1 whose diameter is 4.36 cm, the temperature of smoke layer passed through the vent was maintained 7~$8^{\circ}c$ less than that of smoke layer without a vent. In case of a pool whose diameter is 5.23 cm, the average velocity passed through the vent was decreased when it was close to the fire source. And the maximum delay time was 3.86s. In CASE 1, the ceiling temperature was decreased by approximately 8$^{\circ}C$ and the vertical temperature was decreased by approximately $7^{\circ}c$. In CASE 2, both ceiling and vertical temperature wert decreased by $3^{\circ}c$ and in CASE 3, they were decreased by $2^{\circ}c$ each. It was confirmed that the thickness of smoke layer was maintained uniformly under the 25% height of tunnel through the visualized smoke flow by a laser sheet and the digital camcoder.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1710-1714
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• 2004

The analysis of ventilation performance varying with duct shapes in reefer container of scale-model has studied experimentally. Most container ships have ventilation system of which ducts extended to the bottom for the purpose of efficient exhausting of condensing heat from hold. However, the size of ducts is so over-long that it causes manufacturing troubles. In this study, for various types of duct, flow visualization using smoke and normalized temperature analysis are presented. Finally, the cooling performance are compared respectively.

• 한국가시화정보학회:학술대회논문집
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• 2004.11a
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• pp.14-17
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• 2004

A purpose of this visual experiment is to investigate the effect of reduced frequency qualitatively by examining wake pattern change for insect flying motion. Insect is composed of two pair wing with forewing and hindwing, flying motion of insect is performed pitching and plunging so it makes a separation over the wings. The separation affects at the wake pattern and changed wake pattern has an influence on lift, drag and propulsion. This experiment is conducted by using a smoke wire technique and a camera is fixed at hindwing to take a photograph of wake. An electronic device is mounted below test section to find exact the mean positional angle of wing. The reduced frequency in experiment is 0.15, 0.3 and 0.45. We obtained the result which that reduced frequency is closely related to wake pattern that determines flight efficiency.