• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.1-6
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• 2016

The performance of a set of low-cost optical components used for measuring the optical density of PM particles was evaluated in the present study. To this end, the set of low-cost optical components was replaced with that of general optical components used to measure the PM optical density under identical experimental conditions. The optical densities measured from the set of general optical components were then compared to those obtained from the set of low-cost optical components. While the optical density is measured, another key parameter, the dimensionless extinction constant of PM particles (which is needed to optically measure the PM concentration) was also determined in the present study. The experimental results indicate that the optical density and PM concentration measurements performed by low-cost optical components are feasible, producing trackable variations in the OD and concentrations compared to values obtained from the set of general optical components.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.5
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• pp.668-676
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• 2018

This study has developed a technique to divide the aerosol optical depth of the entire aerosol (${\tau}_{total}$) into the dust optical depth (${\tau}_D$) and the pollution particle optical depth (${\tau}_P$) using the AERONET sun/sky radiometer data provided in Version 3. This method was applied to the analysis of AERONET data observed from 2006 to 2016 in Beijing, China, Seoul and Gosan, Korea and Osaka, Japan and the aerosol optical depth trends of different types of atmospheric aerosols in Northeast Asia were analyzed. The annual variation of ${\tau}_{total}$ showed a tendency to decrease except for Seoul where observation data were limited. However, ${\tau}_D$ tended to decrease when ${\tau}_{total}$ were separated as ${\tau}_D$ and ${\tau}_P$, but ${\tau}_P$ tended to increase except for Osaka. This is because the concentration of airborne aerosols, represented by Asian dust in Northeast Asia, is decreased in both mass concentration and optical concentration. However, even though the mass concentration of pollution particles generated by human activity tends to decrease, Which means that the optical concentration represented as aerosol optical depth is increasing in Northeast Asia.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.9
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• pp.607-614
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• 2015

To provide the clear images from the direct light on electrical board and display devices, anti glare treatment of display cover glass is needed. In this study, the effects of surface treatment temperature, concentration, and etching solution coating thickness of the gel phase on optical elements control such as gloss, haze of reflected light and transmittance, were investigated. Cover glasses were treated at different coating thickness and additive concentration. The optical properties were examined using spectrophotometer, gloss and haze meter. The surface morphology and roughness were measured by the optical microscope and Ra measuring instrument. The etching rate and surface morphologies were dramatically affected by the concentration of acid additive in the viscous gel because of re-crystallization of components in the etching solution, hydrogel formation and coagulant after coating on glass substrate. In our experimental range, cover glass which is surface-treated with various optical properties as well as the morphology uniformity was obtained; in particular, optical properties could be controlled by etching solution coating thickness of the gel phase and the concentration of additive. The gloss was depended on the surface roughness and it showed the linear relationship between optical transmittance and haze of reflected light, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.799-804
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• 1989

A new method for measuring optical phase changes of reflection beam from optical mirror is proposed. The optical phase change is liable to change with varying atmosphere conditions. This optical phase changes are measured against air pressure, temperature, humidity and CO$\_$2/ concentration variations. It is clarified that the optical phase changes are most effected by humidity change.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.101-104
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• 1992

In-doped CdS thin films have been deposited at 150$^{\circ}C$ by simultaneous thermal evaporation of CdS and In. Deposition rate and film thickness were 8A/sec and about 1um, respectively. Indium doping concentration of films varied as Indium source temperature from 500$^{\circ}C$ to 700˚. Properties of In-CdS films have been investigatied by measurements of electrical resistivity, Hall effect, X-ray diffraction and optical trasmission spectra. The conductivity of these films was always n-type. The resistivity, carrier concentration, mobility and optical band gap dependence on Indium source temperature are reported. Carrier concentration and mobility of In-CdS films increased with increasing Indium source temperature: then they decreased. The variation of the optical band gap of In-CdS thin films are related to carrier concentration.

• Proceedings of the Optical Society of Korea Conference
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• 2009.10a
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• pp.32-33
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• 2009

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.4
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• pp.323-329
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• 2004

In situ particle size and volume concentration of suspended sediment was measured at the mouth of Seomjin River Estuary In February 2001, using an optical instrument, 'LISST-100'. Time variation of in situ particle size and concentration shows: (1) during ebb tide, Seomjin River supplies relatively fine-grained particles with less-fluctuated, compared to during flood tide, and well-behaved concentrations following the tidal cycle; and (2) during flood tide, relatively coarse-grained particles with highly variable in size distribution and concentration flow upstream from Kwangyang Bay. This explains a poor correlation $(r^{2}=0.10)$ between sediment concentration and beam attenuation coefficient during flood and a high degree of correlation $(r^{2}=0.80)$ during ebb tide. Relatively fine grained and well defined, monotonous size distribution may promote the correlation between concentration and beam attenuation coefficient due to optical homogeneity of particles during ebb tide. Abundance of large aggregates with time-varying size and shape distributions may be mainly responsible for variations in optical properties of the sediment during flood tide, and thus may confound the relationship between the two variables. The difference in particle sizes and shapes between flood and ebb tides can also be observed on SEM images.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.411-415
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• 1990

The dabsylation of amino acids has been applied to resolve their optical isomers with the use of chiral mobile phase in high performance liquid chromatography. The dabsyl amino acids were successfully separated on reversed phase column($C_{18}$) by adding a chiral L-benzylproline-Cu(II) chelate to the mobile phase. The separation selectivity of the dabsyl amino acid enantiomers was not less than that of dansyl amino acids. The retention order of the dabsyl amino acid enantiomers was as those of the dansyl amino acid enantiomers except dabsyl threonine. The optical selectivity of the dabsyl amino acids increase with pH of the mobile phase and concentration of the chelate, but slightly decreases with concentration of buffer and organic solvent composition. However serine, methionine, valine, and leucine showed a slight decrease in the optical selectivity with increase in pH. The retention times of the dabsyl amino acids decreases with increasing pH and acetonitrile concentration but increases with the concentration of the chiral chelate added. The mechanism of the optical resolution is based on a stereospecific interaction including a intramolecular hydrophobic effect and SN-2 reactivity of the ligand exchange chromatography.It is advantageous to detect absorption at 436 nm, which is less interferent them the other detection systems. The derivatized dabsyl amino acids are stable for a month.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.147-151
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• 2004

In this study, an optical fiber assembly directly coupled with a laser diode or a photo diode is designed to confirm high reliable optical coupling efficiency of optical transmitter(Tx) and receiver(Rx). The optical fiber assembly is fabricated by soldering an optical fiber and a Kovar ferrule using a glass solder after inserting an optical fiber through a Kovar ferrule. The Kovar which has good welding characteristics is applied to introduce laser welding technique. The glass solder has excellent thermal characteristics such as thermal shift delamination compared with PbSn, AuSn solder previously used usually. Furthermore, the glass solder doesn't need fiber metalization and this enables low cost fabrication. However, the glass soldering is high temperature process over 35$0^{\circ}C$ and the convex shape after solidification due to surface tension causes the stress concentration on optical fiber. The stress concentration on the optical fiber increases the optical insertion loss and possibility of crack formation. The shape of glass solder was designed referring to 2-D Axi-symmetric FEM simulation. To test the mechanical reliability, mechanical vibration test and shock test were done according to Telcorida GR-468-Core protocol. After each test, the optical loss of the stress distributed fiber assembly didn't exceed 0.5 dB, which passes the test.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1235-1241
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• 2012

Aluminium (Al)-doped zinc oxide (AZO) thin films with different Al concentrations were prepared by the solgel spin-coating method. Optical parameters such as the optical band gap, absorption coefficient, refractive index, dispersion parameter, and optical conductivity were studied in order to investigate the effects of the Al concentration on the optical properties of AZO thin films. The dispersion energy, single-oscillator energy, average oscillator wavelength, average oscillator strength, and refractive index at infinite wavelength of the AZO thin films were found to be affected by Al incorporation. The optical conductivity of the AZO thin films also increases with increasing photon energy.