• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.112-117
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• 1989

This paper describes to the unit rectangle EB direct writing lithography method using SEM. This method has the constant exposure time to any rectangle pattern. In order to change the EB current according to various rectangle size for the constant exposure time, the supply current of condenser lens in controlled by BITMAP-IV CAD system. By this method, the resizing procedure of density pattern area is not needed to pattern data conversion, and the through-put ofr exposure is increased about 172 times compared with the unit scan exposure method.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.60-64
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• 2014

We report the generation of 3.3-mW single-cycle terahertz (THz) pulses at 1-kHz repetition rate via optical rectification in MgO-doped prism-cut stoichiometric LiNbO3. Efficient pulse-front tilting of 800-nm pulses was realized by an optimized single-lens focusing scheme for radially-symmetric propagation of THz beams. In this geometry, nearly-diffraction-limited THz Gaussian beams with electric field strength as high as 350 kV/cm were generated. The pump-to-THz energy conversion efficiency of $1.36{\times}10^{-3}$ and the extremely high signal-to-noise ratio of ~1:15000 achieved are among the best results for 1-kHz single-cycle terahertz pulse generation ever demonstrated in room temperature operation.

• Food Science and Biotechnology
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• v.14 no.3
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• pp.344-349
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• 2005

Aldose reductase catalyzes the conversion of glucose into sorbitol. Inhibiting this enzyme in diabetes mellitus can delay or prevent pathogenic process. Aldose reductase inhibitor was screened from Korean fermented soybean pastes (Doen-jang) and purified via sequential processes of ethanol extraction, HP-20 column chromatography, ethyl acetate extraction, silica gel column chromatography, and crystallization. Aldose reductase inhibitor was identified as genistein with molecular weight of 270 Da and molecular formula of $C_{15}H_{10}O_5$ based on UV spectrometry, $^1H$ and $^{13}C\;NMRs$, and mass spectrometry. Genistein inhibited aldose reductase of pig lens with $IC_{50}$ level of $20\;{\mu}M$. Because genistein was effective against aldose reductase of animal source, it may be a potential therapeutic agent for diabetic complications.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.95-101
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• 1999

We have studied the 1.54$\mu\textrm{m}$ forward and backward stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SRS) for various $CH_4$pressures by 1.06$\mu\textrm{m}$ Q-switched Nd:YAG laser pumping under a repetition rate of Hz in single pass. We obtained that the output of backward SRS was more efficient than that of the forward SRS. The output energy and conversion efficiency of forward and backward SRS were higher than those of SBS since SRS is a steady state, but SBS is a transient state. In a $CH_4$gas uncirculating system, the output energy of the backward SRS and SBS were reduced the about 47% due to a thermal heating of $CH_4$medium in a focusing region for a repetition rate of 5 Hz. But, the output energy of forward SRS was slightly enhanced by about 8.5% due to the increase of the undepleted pump beam in the backward SRS generation. Inthe Raman half resonator using a dichromatic focusing lens, the conversion efficiency of SRS was more than 37% for a input pump laser energy of 40 mJ.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.8
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• pp.614-619
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• 2013

Recently, remote phosphor is reported for white LED enhancing of phosphor efficiency compared with conventional phosphor-based W-LED. In this study, Remote phosphor was produced by screen printing coating on glass substrate with phosphor contents rated paste and heat treatment. The paste consists of phosphor, lowest softening glass frit and organic binders. Remote phosphor can be well controlled by varying the phosphor content rated paste. After mounting remote phosphor on top of blue LED chip, CCT, CRI, and luminance efficiency were measured. The measurement results showed that CCT, CRI, and luminance efficiency were 6,645, 68, and 1,16l m/W in phosphor 80 wt.% remote phosphor sintered at $600^{\circ}C$.