• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.236-239
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• 2001

In this study, the compound materials of GRT/plastics (HDPE, LLDPE, LDPE, PP and PS) were developed. Their tensile strength, strain at yield and flexural modulus according to the change in CRT content were measured. And, the physical properties of the compound materials that the GRT content was changed in the waste vinyl HDPE and pure HDPE were measured, compared and analyzed. If tile GRT is added to PE plastics, the physical properties were superior to those of PP and PS, and in the case of HDPE, the waste vinyl HDPE had superior physical properties by the GRT content to the pure HDPE.

• Bulletin of the Korean Chemical Society
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• v.24 no.6
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• pp.739-743
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• 2003

New quaternary compounds $ANb_2PS_{10}$ (A = Na, Ag) and $AuNb_4P_2S_{20}$ were synthesized and characterized. The structures of three compounds consist of one-dimensional infinite chains built by [$Nb_2S_{12}$] and [$PS_4$] units. Cation atoms are occupied within the van der Waals gap of sulfur atoms between infinite chains to make -S…$M^+$…S- contacts. There is only one Au atom site and so crystallographically a unit cell contains four equivalent Au atoms in $AuNb_4P_2S_{20}$. This is only the half of the numbers of Na or Ag atoms in $NaNb_2PS_{10}$ or $AgNb_2PS_{10}$. The ratio between $Nb_2PS_{10}$ matrix vs the cation is, therefore, 1 : 1 for Ag and Na, but it is 2 : 1 for Au. Mixed valency in Au or Nb was expected to balance the charge in the latter compound. The electronic structures calculated based on the extended Huckel tight-binding method show that $ANb_2PS_{10}$ (A = Ag, Na) are semiconducting, while $AuNb_4P_2S_{20}$ is metallic, which is not consistent with the experimental results of these three compounds that all exhibit semiconducting property. The result of calculation suggests that $AuNb_4P_2S_{20}$ might be a magnetic insulator. Magnetic measurement experiment exactly proved that the compound is a Slater antiferromagnetic material with the Neels' temperature of 45 K. It is recognized, therefore, that electronic structure analysis is very useful to understand the properties of compounds.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1232-1236
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• 2003

In this work, we fabricated a gas-sensing device based on porous silicon(PS), and its C-V properties were investigated for sensing alcohol vapor. The structure of the sensor consists of thin Au/oxidized PS/PS/P-Si/Al, where the p-Si is etched anisotropically to be prepared into a membrane-shape. We used alcohol gases vaporized from different alcohol (or ethanol) solutions mixed with pure water at 36$^{\circ}C$, similarly with an alcohol breath measurement to check drunk driving. As the result, I-V curves showed typical tunneling property, and C-V curves were shaped like those of a MIS (metal-insulator-semiconductor) capacitor, where the capacitance in accumulation was increased with alcohol vapor concentration.

• Composites Research
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• v.33 no.6
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• pp.321-328
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• 2020

Recently, development of nanocomposite materials for applying in various fields has been actively underway. Of the two-dimensional nanomaterials, graphene nanoplatelets (GnPs) are highly utilized because of their excellent properties, but a problem of strong aggregations is occurred when GnPs are fabricated with polymer nanocomposites, so there is a growing demand for research on the methods of dispersion. In this review paper, the research on GnP nanocomposites with improved properties through various dispersion methods of GnPs. The welldispersed GnP nanocomposites will be applied in more diverse fields in the future.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.04a
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• pp.1.1-4
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• 1999

The toughening mechanism and fracture behavior of rubber/polymer composites were investigated with respect to two factors; (1) the composition ratio of polymers(PPO and PS which have a different chain flexibility) and (ii) the rubber particle size in PPO/PS blend system Izod impact test and fractographic observation of the fracture surface using scanning electron microscope were conducted, Finite element analysis were carried out to gain understanding of plastic deformation(shear yielding and crazing) of these materials.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.6
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• pp.359-366
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• 2019

Experimental and analytical studies on the behavioral characteristics of a pre-stressed (PS) steel girder are conducted to investigate the effects of deviators on the non-linear inelastic properties of the PS system. In this regard, 4 test specimens consisting of a steel H-beam, a straight cable with eccentricity, anchorages, and deviators are built and failure tests are performed under two-point loading. In addition, in-plane elastic deformation theories for the PS system without a deviator, and with three deviators at regular intervals are analytically formulated and solved using a symbolic calculation technique. To verify the validity of the experimental and the proposed analytical theories, the results obtained using FEM models composed of beam elements, rigid beam elements, and truss cable elements, are compared to the experimental results and the analytical solutions. As a result, it is determined that externally installed un-bonded deviators inhibit flexural deformation of the deformed beam to such an extent that their elastic stiffness, and failure strength are significantly improved compared to those of the PS system without deviators.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.12
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• pp.1991-1998
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• 2020

Objective: This study aimed to evaluate and compare the effects of three different diets on the fatty acids (FA) profile and sensory properties of a characteristic Italian fresh cheese: Pecorino "Primo Sale" (PS). Methods: Fifty-four sheep were divided into three feeding groups: total mixed ration (TMR) enriched with extruded linseed (TL), control diet with TMR without any integration (TC), and pasture (P). During cheese production, six cheeses per experimental group were produced each week, stored for 10 days at 4℃, and then analyzed for chemical composition, FA profile, and sensory properties. Results: Saturated fatty acids (SFA) were significantly higher in PS from group TC (82.11%) than in cheese from other two groups (P 75.48% and TL 66.83%). TL and P groups presented higher values of polyunsaturated fatty acids, 4.35 and 3.65%, respectively, than that of TC group (2.31%). The lowest SFA/unsaturated fatty acid ratio was found in TL and P groups, while the highest was found in the TC group. Vaccenic acid and conjugated linoleic acid (CLA) were higher in group P (p<0.05) than in groups L and TC. Sensory properties of cheese from group P received the highest scores for odor intensity and friability, while control group had a greater chewing consistency. Overall, all cheeses received good scores for acceptability. Conclusion: In conclusion, this study showed how the integration of extruded linseed improved the FA profile of fresh pecorino cheese PS preserving its sensory properties. Levels of CLA in the PS group achieved using this approach was not higher than that in a grazing diet. Cheeses from groups P and L contained a higher value of FA, with nutritional implications for humans, when compared with un-supplemented diet. Linseed may be a good feeding strategy when pasture is not available.

• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.190-195
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• 2005

This research was conducted to investigate the changes in soil chemical properties of root media as influenced by incorporation rate of a polyacryl amide hydrogel, Stocksorb C. The pH at 5 weeks after treatment in four root media such as peatmoss + vermiculite (1:1, v/v; PV), peatmoss + composted rice hull (1:1; PR), peatmoss + composted saw dust (1:1; PD) and peatmoss + composted pine bark (1:1; PB) containing STSB were in the range from 7.04 to 7.30, which was too high. Elevated incorporation rate of STSB resulted in increase of EC in soil solution of four root media with linear and quadratic response. The concentrations of $NH_4^+-N,\;NO_3^--N,\;PO_4-P^{3-},\;K^+,\;Ca^{2+}and\;Mg^{2+}$ in four kinds of root media increased as incorporation rates of STSB were elevated. But the $NO_3^-$-N concentrations in PS media were lower than those in other there root media tested. The Fe concentrations in PV, PR and PS media increased as incorporation rates of STSB were elevated, but those in PB medium did not show significant different. The concentrations of $Fe^{2+},\;Mn^{2+},\;Zn^{2+}and\;Cu^{2+}$ in PS media were higher than those in other three root media.

• Journal of the Optical Society of Korea
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• v.10 no.3
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• pp.112-117
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• 2006

We experimentally investigated the transmission characteristics of 400 Gbit/s (10 Gbit/s ${\times}$ 40 channels) WDM signals with 100 GHz channel spacing over 323 km of installed NZ_DSF. The installed fiber has optical properties of 0.28 dB/km attenuation, 4.3 ps/nm/km dispersion, $0.083ps/nm^2/km$ dispersion slope and less than $0.05ps/km^{1/2}$ PMD coefficient. In this experiment, two cases of dispersion compensation schemes, the lumped type and the distributed type, were compared. The results implied that the distributed type dispersion compensation in which dispersion compensation devices are inserted at the end of the each span showed better transmission performance than the lumped one in which dispersion compensation devices are located at the transmitter and receiver sites. From the analysis of the experimental results, we verified that different transmission performance comes from the power penalty induced by XPM in the distributed scheme is lower than the lumped scheme case.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.1
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• pp.77-85
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• 2001

This paper was to investigate the preparation of polysulfone(PS), polyethersulfone(PES) and polyphenylsulfone(PPS) membrane. The thermal property of PPS was higher than that of others. From the result of SEM, the concentration of polymer was found to have a significant effect on the structure of membrane, and the structure of membrane made of PES is found to have regular micell form of asymmetry. Permeability and selectivity for oxygen and nitrogen gas in the air were analyzed by GC. Permeabilities of the membrane made of PES for oxygen and nitrogen in air, 1.5 and $0.7(x10^9[cm^3(STP)cm/cm^2seccmHg]) $, respectively was higher than that of others. and Selectivity of the membrane made of PPS for oxygen to nitrogen gas in air was 2.9.