• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.181-184
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• 2009

In this study, flow visualization method to simulate internal flows of solid rocket motor in a water tunnel is introduced. The tunnel provides excellent visualization of vortex flows and has been used to propellant grain design of the solid rocket motor. A water tunnel is suggested for the research and the visualization test using dye, hydrogen bubble generator and PIV has been studied and discussed.

• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.79-84
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• 2024

As microchips' degree of integration is getting higher, its cooling problem becomes important more than ever. One of the promising methods is using fractal microchannel heat sink by mimicking nature's Murray networks. However, most of the related works have been progressed only by numerical analysis. Perhaps such lack of direct experimental studies is due to the technical difficulty of the temperature and heat flux measurement in complex geometric channels. Here, we demonstrate the direct visualization of in situ temperature profile in a fractal microchannel heat sink. By using the temperature-sensitive fluorescent dye and a transparent Polydimethylsiloxane window, we can map temperature profiles in silicon-based fractal heat sinks with various fractal scale factors (a=1.5-3.5). Then, heat transfer rates and pressure drops under a fixed flow rate were estimated to optimize hydrodynamic and thermal characteristics. Through this experiment, we found out that the optimal factor is a=1.75, given that the differences in heat transfer among the devices are marginal when compared to the variances in pumping power. This work is expected to contribute to the development of high-performance, high-efficiency thermal management systems required in various industrial fields.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.69-79
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• 1997

This paper deals with the measurement and analysis on the scavenging performance of the oppet-valve type two-stroke engine with different shroud system. The scavenging flow characteristics is investigated by flow visualization under steady condition, in which a dye is introduced into single-cycle method using the difference of specific gravity between two working fluids is used to evaluate the scavenging efficiency and the trapping efficiency. The 90° shroud system was found to be the highest efficiency system through both flow visualization and single-cycle test, as well as the shroud system to generally be efficient for reducing a short-circuiting flow during scavenging process in a two-stoke engine.

• Journal of the Korean Society of Visualization
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• v.13 no.2
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• pp.16-21
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• 2015

Concentration polarization(CP) phenomena show great potential on desalination technology. As we can control the dimension of silicon based nanochannel system, it can be used to model ion exchange membrane. In this study, to investigate the effect of nanochannel number and working conditions on the CP based desalination process, nanochannel based microfluidic system is fabricated. First, we optimized nanochannel number and working conditions to conduct visualization study on CP based desalination process. Second, we visualized the desalination process with fluorescent dye in the desalination chip. We also visualized that the particles also can be removed by the CP based desalination process.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.111.1-111.1
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• 2015

As an alternative way to get sophisticated nanostructures, atomic force microscopy (AFM) has been used to directly manipulate building primitives. In particular, assembly of metallic nanoparticles(NPs) can provide various structures for making various metamolecules. As far, conventionally made polygonal shaped metallic NPs showed non-uniform distribution in size and shape which limit its study of fundamental properties and practical applications. In here, we optimized conditions for deterministic manipulation of ultra-smooth and super-spherical gold nanoparticles (AuNPs) by AFM. [1] Lowered adhesion force by using platinum-iridium coated AFM tips enabled us to push super-spherical AuNPs in linear motion to pre-programmed position. As a result, uniform and reliable electric/magnetic behaviors of assembled metamolecules were achieved which showed a good agreement with simulation data. Furthermore, visualization of near field for super-spherical AuNPs was also addressed using photosensitive azo-dye polymers. Since the photosensitive azo-dye polymers can directly record the intensity of electric field, optical near field can be mapped without complicated instrumental setup. [2] By controlling embedding depth of AuNPs, we studied electric field of AuNPs in different configuration.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.19 no.1
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• pp.54-57
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• 2008

Non-visualization of larynx is one of the reasons for failure of vocal fold surgery. Many otorhinolaryngologists may have a trouble in choice of alternative treatment if they experience this situation. The laryngeal mask airway could be alternative approach for this situation. We report a glottal papillomatous patient who was treated by pulsed dye laser via laryngeal mask airway after failure of vocal fold surgery via endotracheal intubation. The patient was a 73-year-old man. Laryngoscopy revealed a severe diffuse papillomatous lesion on right true vocal cord, anterior commissure, and partial left true vocal cord. The patient was refered for difficult laryngeal exposure during laryngomicrosurgey under general endotracheal anesthesia.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2459-2464
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• 2007

In present study, a temperature field of specimens which was coated with fluorescence dye such as Rhodamine-B(Rh-B) has been measured, based on the fluorescence intensity. Silica(SiO2) nano porous structure with 1um thickness was constructed on a cover glass, and fluorescence dye was digested into these porous thin films. To optimize manufacturing coating process, various solvents, Rh-B concentration, and other chemical materials were applied to fabricate the specimen and all specimens were measured on the various temperature conditions. For the measurement, a 14 bit cooled CCD camera with 1600 by 1200 spatial resolution is equipped with epifluorescence microscope to obtain only fluorescence intensity from 1.2 mm by 0.9 mm field of view of the illuminated coated specimen.

• Journal of ILASS-Korea
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• v.6 no.3
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• pp.1-7
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• 2001

In this study, quantitative measurement of nitric oxide concentration distributions visualization were investigated in the laminar $CH_4/O_2N_2$ nixed flame by Planar laser-induced fluorescence(PLIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and $O_2$ fluorescence. The measurements were taken in $CH_4/O_2N_2$ premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flow rate of 3slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to MO formation in $CH_4/O_2N_2$ premixed flame. Furthermore, this trend was well matched with previous works.

• Journal of the Korean Society of Visualization
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• v.11 no.1
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• pp.16-21
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• 2013

In this study, diffusion coefficients of 20 kDa FITC-dextran in 2% agarose gel with different cell concentrations were measured using fiberoptic-based fluorescence recovery after photobleaching technique. As increasing cell concentration suspended in agarose gel, the diffusion coefficients were decreased. The diffusion coefficient of agarose gel which contains $10{\times}10^6$ cells/ml was decreased to 11% that of in agarose gel without cells. The distribution of fluorescence dye in 3D scaffold was also simulated. The simulation result shows that the diffusion coefficient is more significant factor than the scaffold structure.

• Journal of the Korean Society of Visualization
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• v.4 no.2
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• pp.6-10
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• 2006

The functional spherical microcapsules were produced through the innovative conjunction of the well-defined amphiphilic block copolymer and the stable droplet phase flow in the micro chemical plant. The microcapsules were formed to have hollow inner cavity and outer surface wall with nano-pores. To examine the potential of encapsulating foreign biochemical molecules, Congo-red dye was loaded into the microcapsule. The release performance in the specific surroundings such as temperature, pH and time was evaluated quantitatively.