• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.142-145
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• 2010

We made a film of a few ${\mu}m$ thickness by evaporating $As_2S_3$ piece to perpendicularly cut optical fiber by thermal evaporation process. Linear refractive index(n) and linear absorption coefficient(k) of amorphous $As_2S_3$ are 2.525 and $1.727{\times}10^{-3}$, respectively. A surface roughness did not exceed 2 nm and a transmission spectrum showed that the sample of thermal evaporation was homogeneous.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.220-221
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• 2003

Intracavity second harmonic generation of diode pumped solid state lasers in the visible and ultraviolet regions provide efficient, compact and robust light sources for various applications, such as optical data storage, material processing, spectroscopy and bioanalysis. Advantages of neodymium vanadate (Nd：$YVO_4$) as a gain medium for intracavity-doubled lasers over Nd：YAG lie in the facts that the gain spectrum consists of a single line with short absorption depth, and that the stimulated emission cross sections are larger. (omitted)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.853-856
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• 2004

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11b
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• pp.23-26
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• 2004

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current(MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.468-471
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• 2004

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems premising many technical applications. Until now, many methodologies have been developed in order to gain a better understand. Photoisomerization in monolayers of a novel azobenzene compound, azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the third generation of azobenzene dendrimer deposited onto a glass substrate. Temperature-dependent induced charge with trans-cis isomerization was also measured by means of MDC technique.

• Korean Journal of Optics and Photonics
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• v.29 no.4
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• pp.139-148
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• 2018

In this study, aerosol size distributions were retrieved from aerosol optical depth measured over a range of 10 wavelengths from 250 to 1100 nm. The 10 wavelengths were selected where there is no absorption of atmospheric gases. To obtain the solar spectrum, a home-made solar tracking system was developed and calibrated. Using this solar tracking system, total optical depths (TODs) were extracted for the 10 wavelengths using the Langley plot method, and aerosol optical depths (AODs) were obtained after removing the effects of gas absorption and Rayleigh scattering from the TODs. The algorithm for retrieving aerosol size distributions was suggested by assuming a bimodal aerosol size distribution. Aerosol size distributions were retrieved and compared under various arbitrary atmospheric conditions. Finally, we found that our solar tracking spectrometer is useful for retrieving the aerosol size distribution, even though we have little information about the aerosol's refractive index.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.137-140
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• 1993

Electrical properties and thermal annealing effects of $C_{22}$-quinolium(TCNQ) Langmuir-Blodgett(LB) films were studied. Typical current-voltage(I-V) characteristics along the perpendicular direction chow an anomalous behavior of breakdown near the electric-field strength of $10^{6}$V/cm. To see the thermal influence of the specimen, current was measured as a function of temperature(20∼$180^{\circ}C$). It shows that the current increases about 4 orders of magnitude near 60∼$70^{\circ}C$ and remains constant far a while up to ∼$150^{\circ}C$ and then suddenly drops. Such increase of current near 60∼$70^{\circ}C$ seems tn be related to a softness of alkyl chains. Besides the electrical measurements, UV/visible absorption(300∼800 nm) of the thermally annealed sample was measured to see the internal-structure change. It is found that there are four characteristic peaks. At 494 nm, the optical absorption of the thermally annealed specimen at $60^{\circ}C$ starts increase and stays almost constant upto∼ $140^{\circ}C$. And eventually it disappears above $180^{\circ}C$. After heat treatment of the specimen up to $150^{\circ}C$, Uv/visible absorption was measured while cooling.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.175-180
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• 1998

Nd:YAG single crystal widely used as solid state laser was grown by Czochralski method. <111> single crystal with 0.9at% of $Nd^{3+}$ was grown from the Czochralski furnace with a automatic diameter control system. The vertical temperature gradient in the liquid was the major factor that influence the crystal quality, and the crystal diameter was controlled by the home made computer program. The crystal boule with $\phi$50mm$\times$ι100mm effective size was cut, polished, and antireflection coated. The optical evaluation such as absorption spectrum, fluorescence spectrum coincide with typical features of Nd:YAG single crystal. The laser rod was assembled into the CW laser generator with a Kr lamp. The maximum CW laser output was 70 W and the threshold power and efficiency was 1.3kW and 1.64% respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.627-633
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• 2002

Many isolated featureless domains were explicitly observed even at the air-water interface. We measured the surface pressure shift originating from the photo-isomerization of azobenzene units on the periphery of dendrimers. The maximum surface pressure was gradual1y increased and saturated by cyclic compression and decompression. By irradiation of 365 [nm] light, the surface pressure was increased, which was originated by the photo-isomerization process of the azobenzene group on the periphery from trans to cia form. The increase of the dipole moment ($\mu$), which may increase the interaction among Azo dendrimer molecules, made an important role on surface pressure shift. From the absorbance spectrum by UV irradiation and heat treatment, we can see that the absorbance in the UV region decreases with the increase of the UV irradiation time, but the peak at 350 m, characteristic of dendrimers in the LB monolayers, was not shifted until four irradiation cycles. This suggests that optical behavior and morphological change are affected by the functional group and the symmetric chain.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.965-970
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• 2012

Structure and optical properties of cadmium sulphide-zinc oxide composite nanorods have been evaluated by suitable characterization techniques. The X-ray diffraction spectrum contains a series of peaks corresponding to reflections from various sets of lattice planes of hexagonal ZnO as well as CdS. The above observation is supported by the Micro-Raman spectroscopy result. The optical reflectance spectra of CdS-ZnO is compared with that of ZnO where we observe an enhanced absorption and hence diminished reflection from CdS-ZnO compared to that from only ZnO. A very small intensity of the visible photoluminescence peak observed at 550 nm proves that the ZnO nanorods have very low concentrations of point defects such as oxygen vacancies and zinc interstitials. The photocurrent in the visible region has been significantly enhanced due to deposition of CdS on the surface of the ZnO nanorods. CdS acts as a visible sensitizer because of its lower band gap compared to ZnO.