• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11a
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• pp.180-186
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• 1999

Alkaline peroxide bleaching of (chemi) mechanical pulp is a very complicated system where various process factors affect the bleaching performance and pulp properties. Traditional on-factor-at a time method is ineffective and costly in finding the optimal bleaching conditions. In this study statistical experimental methods which include three steps. I. e. screening, response surface modeling and optimization, were used to find the conditions for maximal brightness development during one stage alkaline peroxide bleaching of TMP which had an initial brightness of 54.5% Elerpho. The TMP was pretreated with EDTA(0.5% on O. D. pulp. consistency, $30^{\circ}C$ for 60 minutes) and bleached in a 2L Mark V Quantum Reactor at 750rpm, 7.5% of bleaching consistency and with 0.05% magnesium sulfate addition. The ranges of other factors studied were 1~5% hydrogen peroxide on O. D plup, 1~4% sodium hydroxide on O. D pulp and 1~4% sodium silicate on O. D pulp, reaction temperature 50~$90^{\circ}C$ and reaction time 40~180minutes. A models with good predictability was established and the maximal brightness after one stage bleaching was found to be 70% Elerpho at $50^{\circ}C$, 50 minutes 5% hydrogen peroxide on O. D. pulp 3.2~3.4% sodium hydroxide on O. D. pulp 3.2~3.4% sodium hydroxide on O. D pulp and 4% silicate on O. D pulp. However further studies on other pulp properties such as strength and brightness stability shall be carried out in order to find out the optimal bleaching conditions.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.27-34
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• 2014

In-situ $CaCO_3$ formation onto recycled wood pulp was studied to improve optical properties and ash attachment to the fiber furnish in papermaking. We controlled initial reaction temperature of in-situ $CaCO_3$ formation method from $30^{\circ}C$ to $50^{\circ}C$. It was found that the attachment of newly formed $CaCO_3$ to recycled fibers, old newspaper (ONP) in this case, was stronger than that of ground calcium carbonate (GCC, mean dia. $2.4{\mu}m$) addition case, but was not much different among those formed at different temperature. Morphologies of newly formed $CaCO_3$ were changed according to the reaction temperature. More aragonite shape was seen at higher temperature. In-situ $CaCO_3$ formation increased brightness and lowered ERIC value of ONP sheet greatly at the same level of ash contents when compared to GCC addition method, but gave equivalent ERIC and brightness when compared to those of the precipitated calcium carbonate (PCC) addition method. However, tensile strength of the handsheets of the in-situ $CaCO_3$ formation method were much greater than those of the PCC addition method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.8
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• pp.593-600
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• 2010

In this paper, High brightness LED (light-emitting diodes) driver IC (integrated circuit) using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET (metal oxide semiconductor field effect transistor) from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. To confirm the functioning and characteristics of our proposed LED driver IC, we designed a buck converter. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses 1.0 ${\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre (Cadence) simulation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.42 no.1
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• pp.1-6
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• 2010

Paper industry in Korea produces 14 million tons of paper and 1.3 million tons of sludge per year. Most of them has been treated by incineration, landfilling or ocean dumping. The sludge recycling to minimize the impact on the environment, so its importance is highlighted. In this study, in order to develop a new way of recycling the sludge, it was calcined and the recycled ash was tried to use as papermaking filler. Concerning the yield of calcium carbonate and the brightness and the rheology of the recycled calcination sludge, the optimum calcination conditions were found to be $600^{\circ}C$ and 12 hours. The sludge ash itself was not suitable for papermaking due to its color and low brightness. Thus the ash from the sludge was first mixed with a commercial filler and then utilized for papermaking. The effect of the increased hardness after high temperature treatment on wire abrasion was confirmed.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.1-8
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• 2007

A flat fluorescent lamp (FFL) was developed as a light source for LCD TV Backlight. The channels of FFL were realized by forming the flat glass at high temperature. The performance of the backlight with FFL was shown to improve by optimizing the FFL channel profile that has elliptical shape, 4.4 mm height and 1.4 mm sealing distance. In this paper, the brightness uniformity of LCD TV backlights was investigated by optical simulation of FFL channel profiles. The brightness of LCD TV using FFL with the optimized channel profile was shown to be $576\;cd/m^2$.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.04b
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• pp.361-365
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• 1999

This study examined the effects of multiple recycling on deinkability and properties of recycled paper from laser computer printout (LCPO). First, alkaline paper with a 20% printed area was disintegrated by TAPPI standard disintegrator at room temperature. After dewatering, the pulp was flotated and dried in oven at80$^{\circ}C$ for 24 hrs. A sequence of wetting, disintegrating, flotating and drying was one recycling cycle and this cyclic treatment was repeated from zero to five times. The recycled handsheet dropped to 90% of the original brightness after five cycles, and lost the most brightness after five cycles, and lost the most brightness in the first two cycles. However, it had a gain of 10% in opacity after five cycles as the same as the case of nonprinting. And, in this study, the method for determining residual ink(toner) content in recycled handsheets ere established by means of SEM-EDX and Py-GC. The change of residual ink percentage on recycled paper showed the effect of recycling numbers on deinkability of waste paper. A slight decrease in deinkability was noted for the recycled handsheets, which may be due to the change of fiber surface free energy connected with fiber swelling.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.59.3-59.3
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• 2018

With a recent observational study of extended Lyman-alpha halos around individual high-z star-forming galaxies by Leclercq et al. (2017) using MUSE, we perform radiative transfer calculations to see if Lyman-alpha scattering can explain the spatial extents of the halos together with their spectra. We adopt a spherically-symmetric halo model in which Lyman-alpha sources and neutral hydrogen (HI) medium have exponential density distributions. The HI medium is set to have outflowing motion based on a momentum-driven wind scenario in a gravitational potential well. We run our Lyman-alpha radiative transfer code, LaRT, upon this halo model for various sets of parameters regarding the HI medium such as temperature, optical depth, density scale radius, outflow velocities, and dust content. We analyze simulation results to see the impact of each parameter on Lyman-alpha spectra and surface brightness profiles, and degeneracies between the parameters. We also find a parameter set that best reproduces simultaneously the observed spectra and surface brightness profiles of the MUSE Lyman-alpha halos.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.4
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• pp.42-48
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• 2001

The spent liquor (BSL) obtained from alkaline sulfite-anthraquinone (AS-AQ) cooking of pine bark was applied as a deinking agent. In the ONP deinking system, although BSL removed the small size of ink particles (${\geq}$$12.5{\mu}m$), it did not improve the brightness of pulp. The brightness of pulp slightly improved when treated with BSL at 150~$180^{\circ}C$. However, the brightness of the pulp was lower than that of a commercial deinking agent (oleic acid). It seems that BSL treated with a high temperature still had a high dispersing ability on the ink particles. Intensive oxidations were introduced, and remarkable deinking effects were observed at 13kgf/$cm^2$ oxygen pressure, $160^{\circ}C$ and 2h. When BSL treated at 13kgf/$cm^2$ oxygen pressure, $170^{\circ}C$ and a time period of 30~90 min is added to the pulp, at 0.1% or lower, the deinking effect became higher than that of oleic acid. On the other hand, additional alkali treatments during the oxidation possibility as a deinking agent when oxidized. However, since the oxidized BSL still has a high dispersing ability and lower molecular weight, several modifications need to be done in the near future in order to be applied as a high quality deinking agent.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.4
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• pp.344-349
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• 2005

The optical and electrical characteristics of plasma display panel(PDP) using the vacuum in-line sealing technology compared with the conventional sealing process in this research. This PDP consisted of MgO protecting layer by e-beam evaporation and battier rib, transparent dielectric layer, dielectric layer, and electrodes by screen printer and then sealed off on Ne-Xe(4 ％) 400 Torr and 430。C. The brightness and luminous efficiency were good as the base vacuum level was higher, and it was to check the advantage of high vacuum level sealing, one of the strong points of the vacuum in-line sealing process. However, the brightness and luminous efficiency was dropped sharply because of a crack on MgO protecting layer by the difference of the expansion and contraction stress on high temperature in the vacuum states between MgO and substrate. Fortunately, the crack was prevented by MgO was deposited on higher temperature than 300。C. Finally, the PDP, was fabricated by the vacuum in-line sealing process, resulted the lower brightness than processing only the thermal annealing treatment in the vacuum chamber, but the luminous efficiency was increased by the reducing power consumption with the decreasing luminous current. The vacuum in-line sealing technology was not to need the additional thermal annealing process and could reduce the fabrication process and bring the excellent optical and electrical properties without the crack of MgO protecting layer than the conventional sealing process.

• Atmosphere
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• v.22 no.2
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• pp.137-147
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• 2012

The technique of Brightness Temperature Difference (BTD) between 11 and $12{\mu}m$ separates yellow sand dust from clouds according to the difference in absorptive characteristics between the channels. However, this method causes consistent false alarms in many cases, especially over the desert. In order to reduce these false alarms, we should eliminate the background noise originated from surface. We adopted the Background BTD (BBTD), which stands for surface characteristics on clear sky condition without any dust or cloud. We took an average of brightness temperatures of 11 and $12{\mu}m$ channels during the previous 15 days from a target date and then calculated BTD of averaged ones to obtain decontaminated pixels from dust. After defining the BBTD, we subtracted this index from BTD for the Yellow Sand Index (YSI). In the previous study, this method was already verified using the geostationary satellite, MTSAT. In this study, we applied this to the polar orbiting satellite, MODIS, to detect yellow sand dust over Northeast Asia. Products of yellow sand dust from OMI and MTSAT were used to verify MODIS YSI. The coefficient of determination between MODIS YSI and MTSAT YSI was 0.61, and MODIS YSI and OMI AI was also 0.61. As a result of comparing two products, significantly enhanced signals of dust aerosols were detected by removing the false alarms over the desert. Furthermore, the discontinuity between land and ocean on BTD was removed. This was even effective on the case of fall. This study illustrates that the proposed algorithm can provide the reliable distribution of dust aerosols over the desert even at night.