• Atmosphere
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• v.15 no.3
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• pp.149-153
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• 2005

A balloon-borne Optical Particle Counter (hereafter "OPC Sonde"), which was developed by the atmospheric research group of Nagoya University, is used for getting the information of vertical profile of particle size and concentration in Anmyeon ($36^{\circ}32^{\prime}N$ $126^{\circ}19^{\prime}E$) on 18 March 2005. A range of five different particle sizes is shown in the vertical profile of aerosol number density estimated from the OPC Sonde. It was found that small size particles have vertically larger aerosol number density than relatively big ones. For all size ranges the vertical aerosol number density shows a decreased pattern as the altitude becomes higher. The aerosol number density of $0.3{\sim}0.5{\mu}m$, $0.5{\sim}0.8{\mu}m$, $0.8{\sim}1.2{\mu}m$ size ranges at the 10km height, which is the tropopause approximately, are $1,000,000ea/m^3$, $100,000ea/m^3$, $10,000ea/m^3$ respectively. The data of OPC Sonde are also compared with the data of PM10 $\beta$-ray) and Micro Pulse Lidar which are operating at Korea Global Atmosphere Watch Observatory in Anmyeon.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.49 no.3
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• pp.225-230
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• 2023

In this study, the porous structure inside the hair were observed using an optical microscope without damaging the hair, and the porosity inside the hair was quantitatively expressed using the results. Experiments were conducted on the effect of the decrease in density inside the hair on the bending and tensile properties of the hair, and experiments on endogenous and extrinsic factors were conducted to find out the causes of the decrease in density inside the hair. As for the endogenous factor, the porosity of gray hair, one of the representative symptoms of aging, was compared with normal hair. As for extrinsic factors, it was observed that the internal density of hair decreased by surfactant and heat, which are factors that can cause hair damage in daily life. In addition, we confirmed whether it is possible to increase the internal density and luster of the hair by using an amino acids and material that can prevent hair lipid predisposition.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.242-243
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• 2002

From the dispersion relation of an electromagnetic (EM) wave propagating through plasmas, w$\^$2/ = w$\sub$p/$\^$2/＋c$\^$2/k$\^$2/ the phase velocity (w/k) of the wave is large at high density where w$\sub$p/ is large, and small at low density Therefore, when a laser pulse is located on a downward density gradient of a plasma wave, the phase velocity of the back of the pulse becomes faster than that of the front of the pulse and the pulse wavelength decreases. (omitted)

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.256-258
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• 1998

An experimental study was done to improve the processability and optical property of linear low density polyethylene(LLDPE) film. By modifying the molecular structure of LLDPE with electron beam we could get the improved processability and optical property of film. By appropriate dosing of electron beam and a small addition of UV-stabilizer it was possible to produce gel-free film with low haze. The proceassability was also improved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.565-569
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator for tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified the accuracy of the simulation and the superiority of the presented method.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.41.2-41.2
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• 2012

It has been suggested that merging plays an important role in the formation and the evolution of early-type galaxies (ETGs). Optical-NIR color gradients of ETGs in high density environments are found to be less steep than those of ETGs in low density environments, hinting frequent merger activities in ETGs in high density environments. In order to examine if the flat color gradients are the result of dry mergers, we studied the relations between merging features, luminosities, environments and color gradients of 196 low redshift ETGs selected from Sloan Digital Sky Survey (SDSS) Stripe82. Near Infrared (NIR) images are taken from UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS). Color (r-K) gradients of ETGs with tidal features are a little flatter than relaxed ETGs, but not significant. We found that massive (> 10^11.3 solar masses) ETGs have -40% less scattered color gradients than less massive ETGs. The less scattered color gradients of massive ETGs could be evidence of dry merger processes in the evolution of massive ETGs. We found no relation between color gradients of ETGs and their environments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.358.2-358
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• 2002

To improve the driving sensitivity of an optical pickup actuator for high density and high speed drive, we present a new actuator design using multipolar flux-density distribution by magnetic materials and Nd-Fe-B sintered magnets. We expect this actuator to use in 3-axis actuator fur tilt compensation as well as conventional 2-axis actuator. The electromagnetic field analysis applying 3-D FEM was performed and several samples were actually tested. From comparing simulated data with experimental results, we verified theaccuracy of the simulation and the superiority of the presented method.

• Laser Solutions
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• v.12 no.2
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• pp.17-25
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• 2009

Two methodologies for predicting thermal relaxation time of tissue subjected to pulsed laser irradiation is introduced by the calculation the optical penetration depth and by the investigation of the temperature diffusion behavior. First approach is that both x-axial and y-axial thermal relaxation times are predicted and they are superposed to achieve the thermal relaxation time (${\tau}_1$) for two-dimensional square tissue model. Another approach to achieve thermal relaxation time (${\tau}_2$) is measuring the time required for local temperature drop until $e^{-1}$ of the maximum laser induced heating.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.146-150
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• 2021

Plasma information based virtual metrology (PI-VM) that predicts wafer-to-wafer etch rate variation after wet cleaning of plasma facing parts was developed. As input parameters, plasma information (PI) variables such as electron temperature, fluorine density and hydrogen density were extracted from optical emission spectroscopy (OES) data for etch plasma. The PI-VM model was trained by stepwise variable selection method and multi-linear regression method. The expected etch rate by PI-VM showed high correlation coefficient with measured etch rate from SEM image analysis. The PI-VM model revealed that the root cause of etch rate variation after the wet cleaning was desorption of hydrogen from the cleaned parts as hydrogen combined with fluorine and decreased etchant density and etch rate.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.65-70
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• 2014

This paper presents the simulation and design of an all-optical subtractor using a quantum-dot semiconductor optical amplifier Mach-Zehnder interferometer (QD-SOA MZI) structure consisting of two cascaded switches, the first of which produces the differential bit. Then the second switch produces the borrow bit by using the output of the first switch and the subtrahend data stream. Simulation results were obtained by solving the rate equations of the QD-SOA. The effects of QD-SOA length, peak power and current density have been investigated. The designed gate can operate at speeds of over 250 Gb/s. The simulation results demonstrate a high extinction ratio and a clear and wide-opening eye diagram.