• Korean Chemical Engineering Research
• /
• v.61 no.2
• /
• pp.247-257
• /
• 2023

Precise counting of cell number stands in important position within clinical and research laboratories. Conventional methods such as hemocytometer, migration/invasion assay, or automated cell counters have limited in analytical time, cost, and accuracy., which needs an alternative way with time-efficient in-situ approach to broaden the application avenue. Here, we present simple coding-based cell counting method using image analysis tool, freely available image software (ImageJ). Firstly, we encapsulated RFP-expressing bacteria in a droplet using microfluidic device and automatically performed fluorescence image-based analysis for the quantification of cell numbers. Also, time-lapse images were captured for tracking the change of cell numbers in a droplet containing different concentrations of antibiotics. This study confirms that our approach is approximately 15 times faster and provides more accurate number of cells in a droplet than the external analysis program method. We envision that it can be used to the development of high-throughput image-based cell counting analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2002.04a
• /
• pp.1-1
• /
• 2002

PLLIF(Planar Laser Liquid Induced Fluorescence) 기법은 분무장을 교란시키지 않고 고해상도의 2차원 질량분포를 빠르게 측정할 수 있기 때문에 기존의 기계적인 분무 분포 측정방법의 한계를 극복하였을 뿐만 아니라 접근이 불가능하였던 인젝터 근방의 분무에 대한 중요한 정보를 제공하고 있다. 그러나 레이저 광을 받은 액적에 의한 산란광의 강도가 클 경우에는 인접한 액적들을 형광시킬 수 있고 액적의 형광신호가 액적들을 통과하면서 감쇠되는 이차산란에 의한 오차는 PLLIF 기법의 정량화에 가장 큰 난점으로 인식되고 있다. 특히 이러한 현상은 분무 분포의 밀도가 높고 액적의 크기가 클수록 강하게 나타나는데, 액체로켓에서 일반적으로 사용되고 있는 like-doublet 인젝터는 이러한 분무 특성을 갖는다. 따라서 Mechanical Patternator 및 PDPA(Phase Doppler Particle Analyzer)로부터 측정한 like-doublet 인젝터의 분무 질량 분포 결과와 비교하여 이차산란에 의한 오차를 파악하여 PLLIF 기법의 적용 가능성을 진단하였다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2005.11a
• /
• pp.201-206
• /
• 2005

The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic crossflows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.11a
• /
• pp.59-63
• /
• 2006

A direct photograph measurement technique was used to determine the spatial distribution of the spray droplet diameter in subsonic crossflow and it also obtain that SMD distribution by using PLLIF technique. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of this research are getting a droplet distribution and drop size measurement of normal flow and compare with the other flow effects. Although the study showed visually that drop size were spatially dependent of Air-stream velocity, fuel injection velocity, and normalized distance from the injector exit length.(x/d, y/d) There are also difference characteristics between cavitation, hydraulic flip and the normal flow.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.1
• /
• pp.25-31
• /
• 2004

Two-dimensional laser visualization methods have been used in the study of breakup and atomization processes of non-evaporating diesel sprays. A single-hole spray injected into a quiescent atmospheric environment was visualized by the LIF(Laser Induced Fluorescence) and scattering technique. The LIF technique could be implemented to take the images which are magnified enough to show the shape of liquid ligaments and small droplets. The spontaneous scattering and fluorescent images of sprays were also taken to investigate the atomization of droplets. In the tip and periphery of a spray. the scattering light is bright and the ratio of fluorescent/scattering intensity is lower. This characteristics indicate the very high number density of small droplets which are well atomized.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.4 no.1
• /
• pp.36-45
• /
• 2000

Most researches for impinging jet spray have been focused on under-standing the breakup mechanism of a liquid sheet formed by the collision of jets and modeling the spray breakup using experimental data. For this reason, there have been few studies on the characteristics of the spatial spray distribution which affects significantly the combustion efficiency. Hence, we measured the radial distribution of fuel massflux using a like-doublet type injector. Instead of PDPA(Phase Doppler Particle Analyzer) which has been used only for the point measurement of the drop size of spray, PLIF(Planar Laser Induced Fluorescence) technique was developed lot the 2-D measurement of the massflux distribution of spray Indirect photography technique was also used to verify PLIF data.

• Korean Chemical Engineering Research
• /
• v.44 no.3
• /
• pp.235-242
• /
• 2006

Spray pyrosysis is a process to prepare particles and films by evaporating and decomposing droplets of precursor solutions in the order of 1-10 micrometer in diameter. Key elements of the spray pyrolysis process include precursor, solvent, droplet generator, and reactor. Various combination of these 4 elements produces wide range of particles and films. In general. the current status of the spray pyrolysis technology is not quite promising for commercial success. However, this process will be feasible to produce multicomponent functional materials of controlled morphology. In this paper, current status of the spray pyrolysis technology is introduced with the emphasis of production of fluorescence particles.

• Korean Chemical Engineering Research
• /
• v.55 no.1
• /
• pp.80-85
• /
• 2017

Recently, microalgae which can produce high-value products have attracted increasing attention for biological conversion of $CO_2$. However, low photosynthetic efficiency and productivity have limited the practical use of microalgae. Thus, we developed microdroplet photobioreactor for the analysis of photoautotrophic growth of model alga, Chlamydomonas reinhardtii. $CO_2$ transfer rate was increased by integrating micropillar arrays and adjusting height of microchamber. These results were identified by change of cell growth rate and fluorescence intensity. Lastly, the photoautotrophic growth kinetics of C. reinhardtii in microdroplet photobioreactor were investigated under different $CO_2$ concentrations and light intensities for 96 hours. As a result, microdroplet photobioreactor was efficient platform for isolation and rapid evaluation of microalgal strains which have enhanced productivity of high-value products and growth performance.

• Journal of ILASS-Korea
• /
• v.11 no.2
• /
• pp.113-120
• /
• 2006

The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic cross flows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory and width of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It's also found that the injector internal turbulence influences the spray plume characteristics significantly.

• Journal of the Korean Society of Visualization
• /
• v.21 no.3
• /
• pp.65-74
• /
• 2023

Compared to epifluorescence(EPI) microscopy which captures fluorescence from the entire depth of sample, total internal reflection fluorescence(TIRF) can selectively visualize only a single surface of it. TIRF uses a thin evanescent field generated by the total internal reflection of laser light on surface. However, conventional TIRF system are designed for total internal reflection to occur at the upper surface of sample, making them unsuitable for sessile droplet imaging. We designed a TIRF system suitable for a sessile droplet imaging by utilizing slide glass as a lightguide. We presented the details for constructing the TIRF system using a prism, slide glass, air slit, and optical trap. Then, we compared the TIRF with EPI by imaging the droplet with fluorescent particles during its drying process. As a result, TIRF allows us to distinctly visualize the drying pattern on the bottom surface of droplet.