• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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• pp.52-58
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• 2015

White ledger usually includes white office paper, computer paper, and copy machine paper. Because these grades need high optical properties, fluorescent whitening agents (FWAs) are widely used in the papermaking process. FWAs are the most powerful and effective chemical used to obtain high CIE whiteness and ISO brightness in papers. The rising demand for white or ultra-white papers has increased the use of FWAs. However, FWAs used in white ledger can restrict its use, even though white ledger is widely used as a raw material in paperboard mills. Therefore, it is necessary to develop methods to control FWAs from white ledger to increase its use in paperboard mills. In this study, the behaviors of disulpho fluorescent whitening agent (D-FWA), tetrasulpo fluorescent whitening agent (T-FWA), and hexasulpho fluorescent whitening agent (H-FWA) during the recycling process were identified as a first step to remove FWAs from white ledger. We prepared four types of papers (dyed with D-FWA, T-FWA, and H-FWA), disintegrated these papers, and made handsheets. This recycling process was carried out three times in a laboratory. After each round of recycling, the hand-sheets' CIE whiteness and fluorescence index were measured, and the distribution of FWAs in the Z-direction was observed using CLSM images. FWA reductions in the model papers were calculated using fluorescence indices as a function of the number of recycling. FWAs in handsheets containing T-FWA and H-FWA decreased linearly as a function of the number of recycling, but D-FWA did not show a significant reduction in the fluorescence index after recycling. T-FWA and H-FWA showed similar distributions of D-FWA after recycling. Therefore, as much T-FWA and H-FWA as possible must be detached in the early processes of papermaking at paperboard mills.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.224-229
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• 2011

Zearalenone (ZEA) is an estrogenic mycotoxin mainly produced by Fusarium graminerum, a species which colonizes a wide variety of cereals, including wheat, barley and processed products. A survey of ZEA contamination was conducted on 141 dried confectioneries, 59 breads and rice cakes, 135 noodles and 101 other products, for a total of 432 commercial samples. Samples were analyzed by high performance liquid chromatography with fluorescence detection (HPLC-FLD) after immunoaffinity clean-up and was confirmed by liquid chromatography tandem mass spectrometry (LCMS/MS). The limits of detection and quantification were 2.0 and $6.0{\mu}g/kg$, respectively. The recovery ranged from 80.2% to 98.4% in the cereal based product. ZEA was detected in 38 samples (8.8% incidence), including 3 snack, 2 biscuit and 33 other cereal products. The ZEA contamination levels were in the range of $5.38-53.76{\mu}g/kg$. Finally, LC-MS/MS analysis of the contaminated samples was conducted to confirm the detected ZEA, and all 38 samples showing ZEA by HPLC-FLD were confirmed by LC-MS/MS.

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.22-27
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• 2016

The Electrostatic Charge Prevention Technology is a core factor that highly influences the yield of Ultra High Resolution Flat Panel Display and high-integrated semiconductor manufacturing processes. The corona or x-ray ionizations are commonly used in order to eliminate static charges during manufacturing processes. To develop such a revolutionary x-ray ionizer that is free of x-ray radiation and has function to control the volume of ion formation simultaneously is a goal of this research and it absolutely overcomes the current risks of x-ray ionization. Under the International Commission on Radiological Protection, it must have a leakage radiation level that should be lower than a recommended level that is $1{\mu}Sv/hour$. In this research, the new generation of x-ray ionizer can easily control both the volume of ion formation and the leakage radiation level at the same time. In the research, the test constraints were set and the descriptions are as below; First, In order not to leak x-ray radiation while testing, the shielding box was fully installed around the test equipment area. Second, Implement the metallic Ring Electrode along a tube window and applied zero to ${\pm}8kV$ with respect to manage the positive and negative ions formation. Lastly, the ion duty ratio was able to be controlled in different test set-ups along with a free x-ray leakage through the metallic Ring Electrode. In the result of experiment, the maximum x-ray radiation leakage was $0.2{\mu}Sv/h$. These outcome is lower than the ICRP 103 recommended value, which is $1{\mu}Sv/h$. When applying voltage to the metallic ring electrode, the positive decay time was 2.18s at the distance of 300 mm and its slope was 0.272. In addition, the negative decay time was 2.1s at the distance of 300 mm and its slope was 0.262. At the distance of 200 mm, the positive decay time was 2.29s and its slope was 0.286. The negative decay time was 2.35s and its slope was 0.293. At the distance of 100 mm, the positive decay time was 2.71s and its slope was 0.338. The negative decay time was 3.07s and its slope was 0.383. According to these research, the observation was shown that these new concept of ionizer is able to minimize the leakage radiation level and to control the positive and negative ion duty ratio while ionization.

• Progress in Medical Physics
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• v.19 no.4
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• pp.247-255
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• 2008

A coded aperture camera has been developed to improve the signal-to-noise ratio (SNR) while keeping the spatial resolution of a pinhole gamma camera. The purpose of this study was to optimize a coded aperture camera and to evaluate its possibility for thyroid imaging by Monte Carlo simulation. A clinical gamma camera, a pinhole collimator with 1.0 mm hole diameter, and a $79{\times}79$ modified uniformly redundant array (MURA) mask were designed using GATE (Geant4 Application for Tomographic Emission). The penetration ratio, spatial resolution, integral uniformity and signal-to-noise ratio (SNR) were simulated and evaluated as a function of the mask thickness. The spatial resolution of the coded aperture camera was consistent with the various mask thickness, SNR showed a maximum value at 1.2 mm mask thickness and integral uniformity was improved by increasing mask thickness. Compare to the pinhole gamma camera, the coded aperture camera showed improved SNR by a factor of 30 while keeping almost the same spatial resolution. In this simulation study, the results indicated that high spatial resolution and ultra-high SNR of the thyroid imaging are feasible using a coded aperture camera.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.193-199
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• 1998

The mixtures of ultra-high molecular weight polythylene (UHMWPE), high density polyethylene (HDPE), process oil (mineral oil) and potassium hexatitanate whisker were melted and mixed at $150^{\circ}C$ for 30min, and prepared by compression molding to the specimen of separator of about $200{\mu}m$ thickness at the same temperature and 5000 psi. Thereafter the pores were formed by extracting process oil with organic solvents. In this study, the range of PR (the ratio polymer to process oil) was varied from 0.1 to 0.5 because the specimen turned into rubbery phase at which PR was below 0.1 whereas it changed into gel phase at which PR was above 0.5. When the specimen was treated with nonpolar organic solvents, process oil was extracted nearly 98%. Tensile strength was $31kg/cm^2$ at PR = 0.426, and resistance of specimen was $37m{\Omega}/cm^2$ at PR = 0.186, and $53m{\Omega}/cm^2$ at PR = 0.426. The $N_2$ adsorption-desorption isotherm showed a hysteresis representing regions of capillary condensation, and the surface area at PR = 0.186 was relatively large as $130cm^2/g$. Potassium hexatitanate whisker was randomly dispersed in between PE layers. It might be that the whisker is intercalated through the PE thin layers oriented by compression.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.706-714
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• 2020

Currently, 90 % of the world's population breathes air with a fine dust content exceeding the World Health Organization's annual average exposure limit (10 ㎍/㎥). Global efforts have been devoted toward reducing secondary pollutants and ultra-fine dust through regulations on nitrogen oxides released over land and sea. Domestic efforts have also aimed at creating clean marine environments by reducing sulfur emissions, which are the primary cause of dust accumulation in ships, through developing and distributing environment-friendly ships. Among the technologies for reducing harmful emissions from diesel engines, electrostatic precipitator offer several advantages such as a low pressure loss, high dust collection efficiency, and NOx removal and maintenance. This study aims to increase the durability of a ship by improving equipment quality through failure mode effects analysis for the preventive maintenance of an electrostatic precipitator that was developed for reducing fine dust particles emitted from the 2,427 kW marine diesel engines in ships with a gross tonnage of 999 tons. With regard to risk priority, failure mode 241 (poor dust capture efficiency) was the highest, with an RPN of 180. It was necessary to determine the high-risk failure mode in the collecting electrode and manage it intensively. This was caused by clearance defects, owing to vibrations and consequent pin loosening. Given that pin loosening is mainly caused by vibrations generated in the hull or equipment, it is necessary to manage the position of pin loosening.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.31-40
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• 2017

This paper deals with the high precision of GPS measurement reduction and its implementation on near real-time and kinematic mode for those applications requiring centimeter-level precision of the estimated coordinates, even if target stations are a few hundred kilometers away from their references. We designed the system architecture, data streaming and processing scheme. Intensive investigation was performed to determine the characteristics of the GPS medium-range functional model, IGS infrastructure and some exemplary systems. The designed system consisted of streaming and processing units; the former automatically collects GPS data through Ntrip and IGS ultra-rapid products by FTP connection, whereas the latter handles the reduction of GPS observables on static and kinematic mode to a time series of the target stations' 3D coordinates. The data streaming unit was realized by a DOS batch file, perl script and BKG's BNC program, whereas the processing unit was implemented by definition of a process control file of BPE. To assess the functionality and precision of the positional solutions, an experiment was carried out against a network comprising seven GPS stations with baselines ranging from a few hundred up to a thousand kilometers. The results confirmed that the function of the whole system properly operated as designed, with a precision better than ${\pm}1cm$ in each of the positional component with 95% confidence level.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.389-400
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• 2009

A compression lap splice can be calculated longer than a tension lap splice in high strength concrete according to current design codes. Including effects of transverse reinforcement, a compression splice becomes much longer than a tension splice. Effects of transverse reinforcement and bar size on strength and behavior of compression lap splice, which always exist in actual structures, have been investigated through experimental study of column tests with concrete strength of 40 and 60 MPa. The results of the tests with bar diameters of 22 and 29 mm show that there is no size effect of bar diameter on compression lap splice. Bond strength of small bar diameter may increase. However, large diameters of re-bars are used in compression member and the size effect of re-bars does not have to be considered in compression lap splice. Confined specimens have twice of calculated strengths by current design codes. New design equations for the compression lap splice including the effects of transverse reinforcement are required for practical purpose of ultra-high strength concrete. End bearing is enhanced by transverse reinforcement placed at ends of splice not by transverse reinforcement within splice length. As more transverse reinforcement are placed, the stresses developed by bond linearly increase. The transverse reinforcements at ends of splice a little improve the strength by bond. Because the stresses developed by bond in compression splice with transverse reinforcement are nearly identical to or less than those in tension splice with same transverse reinforcement, strength increment of compression splice is attributed to end bearing only.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.73-80
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• 2013

Polymer cement slurry (PCS) made from organic polymer dispersion and cement has good adhesion to steel, waterproofness and acid resistance due to being of polymer films formed in cement slurry. The purpose of this study is to evaluate the mix design conditions at early curing age of PCS-coating material effected on improvement in bond strength of coated rebar. The test pieces are prepared with two types of polymer dispersions such as St/BA and EVA, four polymer-cement ratios, two types of cement, four coating thicknesses and three curing ages, and tested for the bond strength test. From the test results, in general, bond strength of PCS-coated rebar is better than that of uncoated rebar and epoxy-coated rebar. It is also high bond strength at curing ages of 7-day or less, and coating thicknesses of $75{\mu}m$ and $100{\mu}m$. The maximum bond strength of PCS-coated rebar at curing age of 3-hour is almost same as that of curing age of 1-day and 7-day. The maximum bond strength of PCS-coated rebar with ultra high-early strength cement and St/BA at polymer-cement ratio of 80%, and coating thickness of $100{\mu}m$ is about 1.52 and 1.58 times respectively, the strength of uncoated rebar and epoxy-coated rebar. It is apparent that the curing age, coating thickness, type of polymer and cement are very important factors to improve the bond strength of PCS-coated rebar to cement concrete. We can have basic information that PCS-coated rebar with curing age at 3-hour and coating thickness of $100{\mu}m$ can replace epoxy-coated rebar.

• Journal of Broadcast Engineering
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• v.17 no.5
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• pp.827-837
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• 2012

As broadcasting environments change rapidly to digital, user requirements for next-generation broadcasting service which surpass current HDTV service become bigger and bigger. The next-generation broadcasting service progress from 2D to 3D, from HD to UHD and from 5.1ch audio to more than 10ch audio for high quality realistic broadcasting service. In this paper, we propose 10.2ch based multichannel audio reproduction system for UHDTV. The 10.2ch-based audio reproduction system add two side loudspeakers to enhance the surround sound localization effect and add two height and one ceiling loudspeakers to enhance the elevation localization effect. To evaluate the proposed system, we used APM(Auditory Process Model) for objective localization test and conducted subjective localization test. As a result of objective/subjective localization test, the proposed system shows the statistically same performance compare with 22.2ch audio system and shows the significantly better performance compared with 5.1ch audio system.