• Journal of Food Hygiene and Safety
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• v.39 no.2
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• pp.152-162
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• 2024

In this study, we investigated the levels of the natural preservatives, benzoic acid, sorbic acid, and propionic acid, in raw unprocessed vegetables. Quantitative analysis of benzoic acid and sorbic acid was performed using high-performance liquid chromatography with a diode array detector (HPLC-DAD) and confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Propionic acid was analyzed using a gas chromatography-flame ionization detector (GC-FID) and confirmed using gas chromatography-mass spectrometry (GC-MS). From a total of 497 samples, benzoic acid, sorbic acid, and propionic acid were found in 50 (10%), 8 (0.2%), and 61 samples (12.3%), respectively. The highest quantity of benzoic acid, sorbic acid, and propionic acid was found in peony root (1,057 mg/kg), nut-bearing torreya seeds (27.3 mg/kg), and myrrha (175 mg/kg), respectively. The background concentration range of naturally occurring preservatives in raw vegetables determined in this study could be used as standard inspection criteria to address consumer complaints and trade disputes.

• Progress in Medical Physics
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• v.5 no.2
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• pp.3-12
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• 1994

$\^$137/Cs gamma ray induced thermoluminescenc(TL) from Na$\^$+/ ion implanted Al$_2$O$_3$ and unimplanted Al$_2$O$_3$ and the TL from Na$\^$+/ ion implanted Al$_2$O$_3$ are measured over the temperature range of 340K～620K. The TL curve of Na$\^$+/ ion implanted Al$_2$O$_3$ induced by $\^$137/Cs gamma ray is split into iolated TL peak located at 415K, 452K, 508K, and 568K. Because that the concentration of trapped char he carries of $\^$137/Cs gamma ray induced Al$_2$O$_3$ implanted with Na$\^$+/ ion is larger than that of Na$\^$+/ ion only implanted Al$_2$O$_3$, and the trap concentration of Na$\^$+/ ion implanted Al$_2$O$_3$ is much than that of $\^$137/Cs gamma ray only irradiated Al$_2$O$_3$, the TL intensity of Na$\^$+/ ion implanted Al$_2$O$_3$ induced by $\^$137/Cs gamma ray is about 20 times and 5 times higher than that of Al$_2$O$_3$ only implanted with Na$\^$+/ ion and Al$_2$O$_3$ only irradiated with $\^$137/Cs gamma ray, respectively. In proportion as ion implantation does and energy are incresed, the number of generated defects and the rate of defect creation are incresed, respectively. Therefore the TL intensity of ion implanted Al$_2$O$_3$ is depend on ion dose and energy. Acccrding to increse of incident ion mass, the TL intensity of ion implanted Al$_2$O$_3$ is abruptly decresce. This result showes that the TL intensity of ion implanted Al$_2$O$_3$ is closely related to ion depth range as wll as rate of defect creatin. The TL intensity of ion implanted Al$_2$O$_3$ is found to be related with defects generated by ion implantation. Table Caption

• The Journal of the Petrological Society of Korea
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• v.20 no.3
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• pp.161-172
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• 2011

Open beaker digestion method is routinely used as the sample preparation technique for trace element determination of rock samples by inductively coupled plasma mass spectrometry, With this method, however, dissolution of Zr and Hf is not always guaranteed especially when the samples contain refractory minerals. In this study, glass bead digestion technique was compared with conventional open beaker digestion technique for the sample preparation of three USGS rock standards such as AGV-2, BHVO-2, and G-3. Thirty trace elements including rare earth elements were analysed by ICP-MS and ICP-AES. There were no clear differences in analytical results for the AGV-2 and BHVO-2 standards between the two techniques, but Zr, Hf, Y, and middle- to heavy- rare earth element concentrations of the G-3 standard prepared by open beaker digestion technique were significantly lower than the recommended values. This can be attributed to the presence of refractory mineral zircon. On the contrary, all the analytical results of the G-3 standard prepared by glass bead digestion technique were in good agreement with the recommended values, indicating complete dissolution of zircon. The analytical results show that the volatile elements such as Pb and Zn were not lost during the preparation of glass bead. Low dilution glass bead digestion technique described here will be very helpful to enhance precision and accuracy of trace element analysis for geological samples containing refractory minerals.

• Clean Technology
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• v.25 no.2
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• pp.107-113
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• 2019

Numerical model that considered the shrinking core model and elutriation and degradation of particles was developed to predict selective chlorination of ilmenite and carbo-chlorination of $TiO_2$ in a two stage fluidized bed chlorination furnace. It is possible to analyze the fluidized bed chlorination reaction to be able to reflect particle distribution for mass balances and the chlorination reaction. The numerical model showed an accuracy with error less than 6% compared with fluidized bed experiments. The chlorination degree with particle size change was greater with a smaller particle size, and there was a 100 min difference to obtain a chlorination degree of 1 between $75{\mu}m$ and $275{\mu}m$. This was not shown to such a great extent with variation of temperature ($800{\sim}1000^{\circ}C$), and there was only a 10 min difference to obtain a chlorination degree of 0.9. In the first selective chlorination process, the mass reduction rate approached to the theoretical value of 0.4735 after 180 min, and chlorination changed the Fe component into $FeCl_2$ or $FeCl_3$ and showed nearly 1. In the second carbo-chlorination process, the chlorination degree of $TiO_2$ approached 0.98 and the mass fraction reached 0.02 with conversion into $TiCl_4$. In the first selective chlorination process, 98% of $TiO_2$ was produced at 180 min, and this was changed into 99% of $TiCl_4$ after an additional 90 min. Also the mass reduction rate of $TiO_2$ was reduced to 99% in the second continuous carbo-chlorination process.

• Journal of the Korean earth science society
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• v.25 no.6
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• pp.495-501
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• 2004

Using numerous ground-based or space-based telescopes by many astronomers, AGN spectroscopic monitoring campaigns have been carried out over many years to study the variability of continua and emission lines. We investigate the SWP IUE spectra of a large aperture configuration for the Seyfert 1 galaxies NGC 4151 and NGC 5548. We estimate the BLR electron number densities and their variation from the line ratios of C III] 1909 to Si III] 1892. With the ratios of C IV 1550 to C III] 1909 which give us the information on the ionization parameter of BLR, we try to find the physical conditions of the BLR and activities of he super massive black hole surroundings. The BLR density variations scale as 4 and 8 for NGC 4151 and NGC 5548, respectively. Based on the BLR size and C III] line profiles, we found both black hole masses as about $10^7$ $M_{\odot}$.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.35-42
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• 1992

Thermal behavior of residue and damaged layer formed by reactive ion etching (RIE) in $CHF_3/C_2F_6$ were investigated using X-ray photoelectron spectroscopy(XPS) and secondary ion mass spec-trometry(SIMS) techniques. Decomposition of polymer residue film begins at $200^{\circ}C$ and above $400^{\circ}C$ carbon compound as graphite mainly forms by in-situ resistive heating. It reveals that thermal decomposition of residue can be completed by rapid thermal anneal treatment above $800^{\circ}C$ under nitrogen atmosphere and out-diffusion of carbon and fluorine of damaged layer is observed.

• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.361-368
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• 2016

A ship's rolling motion can make crew and passengers sick and/or apply forces to the structure that cause damage.. Therefore bilge keels are equipped in most ships for anti-rolling. In special cases, anti-rolling tanks (ARTs), fin stabilizers, or gyroscopes can be installed. However, ARTs require a large area to install, and fin stabilizers and gyroscopes are costly to install and expensive to operate. This paper suggests a Anti-rolling pendulum (ARP) to reduce roll motion. ARPs acts like ARTs. However, the ARP has a circular shaped guidance arc instead of the string or wire of a simple pendulum. The device suggested has about 1/ 8 the weight and 1/ 6 the volume of a ART and is more effective. This study derives the nonlinear and linear differential equations of system motion.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.2
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• pp.65-74
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• 2013

Objectives: This study attempted to develop a method to measure ultra-trace lead concentrations in plasma using Inductively Coupled Plasma Mass Spectrometry(ICP-MS) and to test whether plasma lead can be used as a biomarker for the biological monitoring of exposure to lead. Methods: Lead concentrations in 160 plasma samples of field workers and 42 plasma samples from the control group were measured by ICP-MS. Blood zinc protophorphyrin(ZPP) concentrations and urinary ${\delta}$-aminolevulinic acid${\delta}-ALA$) were measured for correlation analysis with plasma lead. Results: The mean lead level in the plasma of the workers exposed to lead at work were 786.1 ng/L. Plasma lead levels were not correlated with blood ZPP or urinary ${\delta}-ALA$ concentrations. Otherwise, plasma lead levels showed a good correlation coefficient of 0.400 with blood lead levels, and their correlation coefficient had a better value of 0.552 for the non-smoking and drinking group. In the general population group which was not exposed to lead in the workplace and was considered the control group, the mean concentration of plasma lead was 123.1 ng/L. The plasma lead levels for the general population group showed a good correlation coefficient of 0.520 with blood ZPP and urinary ${\delta}-ALA$ concentrations.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.572-579
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• 2017

Determination of the wood content in wood plastic composite (WPC) is crucial to form reliable WPC market. WPC with simple formulation consisting of only two components (wood flour and polypropylene) was examined using thermogravimetric analysis (TGA) and accelerator mass spectrometry (AMS) for determining wood content in the WPC. TGA method using derivative peak temperature (DTp) of polypropylene under low heating rate ($5^{\circ}C/min$) showed more reliable calibration curve and lower error factor compared to method of using the percentage of weight loss of wood flour. In addition, AMS using bio-based carbon content showed greater reliability for the determination of wood content in the WPC in comparison with the TGA method.

• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.643-650
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• 2020

The materials with a high processiblity for radiation shielding, in particular for 3D printable materials, are highly demanding for producing robots working in nuclear plants and designing customized personal protection equipment. In this study, we suspend tungsten particles in a polymeric matrix of either PLA or ABS to compose tungsten-polymer composite filaments; PLA and ABS are widely used for conventional FDM-based 3D printing. The weight fraction of tungsten particles can be increased up to 50% without forming macroscopic aggregates. The composite filaments can be used to print 3D architectures with any shape and geometry. To demonstrate one of potential applications, we print parts for robot actuator and assemble them to protect PCB against gamma ray.