• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.15-20
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• 2009

In a detection system based on laser light scattering, focusing an excitation laser beam into a focal point of a channel in a microfluidic chip is important for obtaining the highest excitation intensity, and consequently for obtaining a laser light scattering signal using a photodetector with a high efficiency. In this paper, we present a polydimethylsiloxane (PDMS) microfluidic chip consisting of an integrated PDMS microlens for cell detection based on laser light scattering. We fabricated PDMS microlens for optical detection system by simply putting down on PDMS chips. The PDMS microlens was fabricated by photoresist reflow and replica molding. This fabrication technique is simple and has an excellent property in terms of the microlens and a high-dimensional accuracy. The PDMS microlens integrated on the PDMS microfluidic chip has been verified to improve the laser intensity, and accordingly, the signal-to-noise ratio and sensitivity of laser light scattering detection for red blood cells(RBCs)

• Korean Journal of Optics and Photonics
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• v.8 no.4
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• pp.345-352
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• 1997

Recently, in designing optical mask such as 4GDRAM, the scattering effect of electromagnetic wave must be considered. For this reason we claculated directly the mask function using the finite difference time domain(FDTD) method. The modification of image theory with this new mask function could explain clearly the scattering effect at the etched side wall of the submicron optical mask. The characteristics of the various type of alternating PSM were investigated. According to the simulation, the dual wet etch process was the most useful fabrication technique to overcoe the light scattering off at the shifted opening.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.682-685
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• 1991

Solvent dependence of the static solution properties of a polymer chain was studied by static light scattering technique for polystyrene in three good solvents, toluene, tetrahydrofuran and $CCl_4$. The molecular parameters such as radius of gyration and second virial coefficients of polystyrene are found to be clearly larger in THF than the other two solvents and they are in the order of tetrahydrofuran > toluene > $CCl_4$. The radius of gyration shows the same order while the difference is smaller. Nontheless, the penetration functions are found to have a comparable value about 0.2, which confirms the universality of the penetration function in high expansion regime over different nature of solvents.

• Particle and aerosol research
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• v.15 no.2
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• pp.67-78
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• 2019

Since existing measurement sites are required to construct a high-cost PM measuring device and a measuring site of a large area, there is a limit to the construction of a high-resolution measurement network. Therefore, it is necessary to develop a low-cost, high-performance PM measuring device (as an alternative technology) that can increase the resolution of PM measurement, and it is necessary to establish a base to provide real-time PM information for whole people. Therefore, in this study, the alternative technique (light scattering method) for achieving the above object was examined, performance evaluation was carried out, and it was verified that the light scattering method was usable. Various PM measurement results were compared and analyzed to find PM monitoring points and resolutions we would like to propose.

• Journal of the Korean Vacuum Society
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• v.14 no.3
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• pp.143-146
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• 2005

A new method of x-ray photon correlation spectroscopy (XPCS) using coherent x-rays is developed recently for probing the dynamics of surface height fluctuations as a function of lateral length scale. This emerging technique applies the principles of dynamic light scattering in the x-ray regime. The short wavelength and slow time scales characteristic of XPCS extend the phase space accessible to scattering studies beyond some restrictions by light and neutron. In this paper, we demonstrate XPCS to study the dynamics of surface fluctuations in thin supported polymer films. We present experimental verification of the theoretical predictions for the wave vector and temperature dependence of the capillary wave relaxation times for the supported polymer films at melt for the film thicknesses thicker than 4 times of the radius of gyration of polymer. We observed a deviation from the conventional capillary wave predictions in thinner films. The analysis will be discussed in terms of surface tension, viscosity and effective interactions with the substrate.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.480-483
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• 2018

In this paper, we study the interference canceling and image sensing processing technology of multiple light sources for high speed transmission in CMOS sensor based visible light communication system. To improve transmission capacity in optical camera communications via image sensors, different data must be transmitted simultaneously from each LED. However, multiple LED light source environments for high-speed transmission can cause interference between adjacent LEDs. In this case, since the visible light communication system generally uses intensity modulation, when a plurality of LEDs transmit data at the same time, it is difficult to accurately detect the respective LEDs due to the light scattering interference of the adjacent LEDs. In order to solve this problem, the ON / OFF state of many LEDs of the light source is accurately recognized by using a dual CMOS sensor, and the spectral estimation technique and the pixel image signal processing technique of each LED are proposed. This technique can accurately recognize multiple LED pixels and improve the total average bit error rate and throughput of a MISO-VLC system.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.113-121
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• 2002

The distribution of volume fraction, mean diameter and number density of soot particles are measured quantitatively in a co-flow ethylene diffusion flame using a simultaneous LII/LIS measurement technique. The LII/LIS system and the measured values are, respectively, calibrated and evaluated by comparing to the informations obtained from laser light. extinction/scattering experiments, LII signal shows some sensitivity to the laser light intensity when laser power density exceeds a certain value(threshold). It is also found that there is an optimal laser intensity and a delay time in order to obtain the best result using the simultaneous LII/LIS measurement technique.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.441-448
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• 2017

A method for measuring the concentration of surfactant in water was developed. In this technique, microbubbles were used as light scatterers. The polarization change of light scattered by microbubbles was analyzed by Mueller matrix analysis. $M_{11}$, one of the Mueller matrix elements, was found to be a key parameter inferring the surfactant concentration within the concentration range of 0 ppm to 60 ppm. The best results for this measurement were obtained when the scattering angle was $150^{\circ}$ and the extinction ratio was 56.2. This experimental result shows that the EPLS can be effectively used as a real time inspection method for water quality monitoring in lakes or rivers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1218-1223
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• 2004

Porous silicon materials have been shown to have bright prospects for applications in light emitting, solar cell, as well as light- and chemical-sensing devices. In this report, structures of porous silicon prepared by anodic etching in HF-based solution with various etching times were studied in detail by Atomic Force Microscopy and Small Angle X -ray Scattering technique using the high energy beam line at Pohang Light Source in Korea. The results showed the coexistence of the various pores with nanometer and submicrometer scales. For nanameter size pores, the mixed ones with two different shapes were identified: the larger ones in cylindrical shape and the smaller ones in spherical shape. Volume fractions of the cylindrical and the spherical pores were about equal and remained unchanged at all etching times investigated. On the whole uniform values of the specific surface area and of the size parameters of the pores were observed except for the larger specific surface area for the sample with the short etching time. The results implies that etching process causes the inner surfaces to become smoother while new pores are being generated. In all SAXS data at large Q vectors, Porod slope of -4 was observed, which supports the fact that the pores have smooth surfaces.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.2
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• pp.129-134
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• 1995

Bulk properties of single crystals $KMnCl_3$ undoped and Mg- doped $LiNbO_3$ were examined by using the neutron scattering technique. This study shows that the good -looking samples by polarized light have to be examined by the. neutron scattering to ensure the bulk properties of single crystal. Large mosaic spread in KMnCb indicated the crystal is not in a single domain. Many parts are relatively randomly directed against crystal axis with close angle each other. For the small mosaic spread of Li~ in the scattering pattern, it is found that some large domains have close orientations. Mg doped Li~ is turned out to be a well grown one.