• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.57-63
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• 1999

The optical absorption and transmittance of cow' crystalline were measured by spectrophotometer in the 200~800nm wavelength regions. The optical absorptions of crystalline composed of a high absorption band in the UV-A, UV-B, and appeared the light transmittance edge in the 400nm wavelength region, and completely transmitted without the absorption in the high wavelength regions than 400nm. Also, the optical absorption and transmittance had no temperature dependence. The optical transmittance spectrum of crystalline concord with the thin film structure of $n_0/(0.5H)L(LH)^6(0.5H)/n_s$ and $n_0{\mid}(0.5LH0.5L)^kL/1.25{\mid}4.0$ of long-pass edge filter form. In the artificial crystalline and inter lens layout, long-pass edge filter layout can UV cut off.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.193-197
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• 2000

A polarized mode convertible, wavelength tunable optical filters with acoustic barriers and acousto-optic effect have been produced in LiNb03 substrate utilizing the Ti double diffusion technique. Polarization conversion in excess of 81 % and a spectral width of -200 kHz (-1.83 nm) were achieved at a wavelength of 1551.6 nm and RF frequencies of 173.07 kHz and 173.05 kHz for both transverse electric (TE) and transverse magnetic (lM) input polarizations, respectively. The electrical driving power was 10.97 mW and reduced to about 10% of one for an optical filter without an acoustic barrier. A linear tuning rate of 8.2 nmlMHz and sidelobe intensity of -4 dB was demonstrated. rated.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.20-24
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• 2008

A color filter was proposed and demonstrated by incorporating a subwavelength patterned 1-dimensional grating in poly silicon. It was produced by employing the laser interference lithography method, providing much wider effective area compared to the conventional e-beam lithography. A $SiO_2$ layer was introduced on top of the silicon grating layer as a mask for the etching of the silicon, facilitating the etching of the silicon layer. It was theoretically found that the selectivity of the filter was also improved thanks to the oxide layer. The parameters for the designed device include the grating pitch of 450 nm, the grating height of 100 nm and the oxide-layer height of 200 nm. As for the fabricated filter, the spectral pass band corresponded to the blue color centered at 470 nm and the peak transmission was about 40%. Within the effective area of $3{\times}3mm^2$, the variation in the relative transmission efficiency and in the center wavelength was less than 10% and 2 nm respectively. Finally, the influence of the angle of the incident beam upon the transfer characteristics of the device was investigated in terms of the rate of the relative transmission efficiency, which was found to be equivalent to 1.5%/degree.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.9
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• pp.910-914
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• 2007

We present a simple and an inexpensive method for the fabrication of a nano-fluidic filter and a nano-pore micromixer using self-assembly of nano-spheres and surface tension. Colloid-plug was formed by surface tension of liquid in a microchannel to fabricate nanofluidic filter. When colloid is evaporated, nano-spheres in a colloid are orderly stacked by a capillary force. Orderly stacked nano-spheres form 3-D nano-mesh which can be used as a mesh structure of a fluidic filter. We used silica nano-sphere whose diameter is $567{\pm}85nm$, and silicon micro-channel of $50{\mu}m$-diameter. Fabricated nano-fluidic filter in a micro-channel has median pore diameter of 158nm which was in agreement with expected diameter of the nano-pore of $128{\pm}19nm$. A nano-pore micromixer consists of $200\;{\mu}m-wide,\;100\;{\mu}m-deep$ micro-channel and self-assembled nano-spheres. In the nano-pore micromixer, two different fluids had no sooner met together than two fluids begin to mix at wide region. From the experimental study, we completely apply self-assembly of nano-spheres to nano-fluidic devices.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.35-39
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• 2010

Purpose: The aim of this study was to investigate distribution of particle size in phytate kit and compare filtered method with non-filtered method using 200 nm filter for sentinel lymphoscintigraphy (SLS). Materials and Methods: Five phytate kit of having the same available period was measured by particle size analyzer. For in-vivo experiment, $^{99m}Tc$-phytate was injected intradermally at both foot to perform lymphoscintigraphy. Imaging was acquired at 1hour after injection. Region of interest (ROI) was drawn in inguinal and background area for analysis. RAW 264.7 cells (Murine macrophage cell) were prepared for measurement of celluar uptake as a representative of macrophages. Paired t-test was performed using SPSS (SPSS Inc, USA) for statistical analysis. Results: The size of most particle in Techne phytate kit was distributed in 130~650 nm(90.5 %). In-vivo study, the ROI analysis showed similar result between filtered and non-filtered sample, and the numerical value of count/pixel were $58.3{\pm}5.97$ and $60.2{\pm}4.88$. In-vitro study, cellular uptake study also showed no difference between filtered and non-filtered sample by gamma counting. Conclusion: The present study demonstrates that there was no meaning of 200 nm filtered method for SLS using $^{99m}Tc$-phytate.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.1
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• pp.62-71
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• 2011

There is widespread concern that particulate filtering respirators (PFRs) available in Korea will be efficient for nanoparticles. The purpose of this review study was to analyse research literature and recommend PFRs suitable for protection against nanoparticles. In all studies, respirators containing electret filter media (N95, P100 and FFP2, FFP3) consistently have their MPPS below 100 nm and particle penetration levels at the MPPS can vary widely, but they comply with NIOSH or EN certification criterion. Electret filtering facepieces respirators (FFRs) were found to shift in the Most-Penetrating Particle Size(MPPS) from 30-60 to 200-300 nm range after the electric charges were removed, and FFRs were above their minimum penetrations of criterion. Korean special class and first class FFRs (the same as FFP3 and FFP2, respectively) would be effcient for nanoparticles unless FFRs are removed electric charges. It is difficult to evaluate if mechanical PFRs is efficient for nanoparticles due to the lack of related materials.

• Korean Journal of Optics and Photonics
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• v.9 no.6
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• pp.413-416
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• 1998

We have flattened the gain of EDFA by using a long-period FBG filter and AOTF's. The gain and optical SNR characteristics of the gain-flattened EDFA in long-haul transmission been evaluated in a recirculating EDFA loop. The gain variation was less than 4.6 dB and the optical SNR was higher than 14 dB over 20-nm wavelength range when the optical signal went through the EDFA as many as 200 times. These results indicate that this gain-flattened EDFA is applicable for ultra long-haul WDM optical transmissions over 8000 km.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.760-768
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• 2000

Filter efficiency of electrically charged particle in uncharged fibrous filter was measured. In previous studies, the effect of charged particle on filter efficiency was investigated but there was difficulty in measuring of image effect that is appeared at the charged small particle. We could easily measure the image effect with charging small particles by photoelectric charging. The spark discharge aerosol generator and a differential mobility analyzer (DMA) were used to generate sub-micron monodisperse particles (${\leq}200$ nm). The generated particles were charged in photoelectric charging process using ultraviolet lamp and electric field. The filter efficiency of the charged particles, classified by another DMA, was measured in filter tester using a condensation nucleus counter (CNC) as function of particle diameter, particle charge and airflow velocity. It is shown that the filter efficiency increases with increasing charge number of the particle and is affected by particle size and flow velocity. Single fiber filter efficiency mainly depends on image force parameter and peclet number. The peclet number was not considered at previous other papers. We propose a modi fied experimental correlation as function of image force parameter and peclet number.

• Korean Journal of Optics and Photonics
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• v.34 no.4
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• pp.151-156
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• 2023

We propose to implement cost-effectively a high-speed short-haul interconnect by transmitting a 200-Gb/s/λ two-channel optical time-division-multiplexed signal generated by a carrier-suppressed optical pulse, which improves the robustness of the multiplexed signal to chromatic dispersion. The multiplexed 200-Gb/s signal is generated in the transmitter by combining two 100-Gb/s 4-level pulse-amplitude-modulated signals (generated using the optical pulse and two Mach-Zehnder modulators). After the signal is transmitted over a fiber, it is amplified by a semiconductor optical amplifier and detected by a photodiode. The amplified spontaneous emission noise is eliminated by an optical band-pass filter. The transmitted signal is reconstructed by a 2 × 2 multiple-input multiple-output equalizer, which compensates for crosstalk. Due to the use of the carrier-suppressed optical pulse, the 200-Gb/s signal can be transmitted over fiber with a chromatic dispersion of 40 ps/nm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.359-365
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• 1997

$K_2CoCl_4$, single crystals were grown by the Czochralski method in Ar atmosphere. The thermal hysteresis of the dielectric constant at $T_c$ was investigated. $K_2CoCl_4$ crystal shows ionic hopping mechanism due to $K^+$ ion and the activation energy is nearly 0.62 eV. Thermal expansions along a-, b-, and c-axis of $K_2CoCl_4$, were measured on heating and the thermal expansion coefficients in each phase were calculated. From the result of the optical absorption measurement, we interpreted the absorption peak as transition energy between the splitted energy levels of the Co ion in the crystal field and it showed the possibility of the application to the optical band filter between 800 nm and 1200 nm.