• Korea-Australia Rheology Journal
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• v.16 no.3
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• pp.135-140
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• 2004

Morphological and rheological properties of the poly(methyl methacrylate) (PMMA) and polystyrene (PS) blends were studied by scanning electron microscopy (SEM) and advanced rheometric expansion system (ARES). From the SEM results, the PMMA-PS blends showed dispersed morphology and the particle size of the dispersed phase was quite small (0.1~0.6 $\mu\textrm{m}$ compared with other immiscible polymer blends. Values of the interfacial tension of the PMMA-PS blend were obtained from the Choi-Schowalter and the Palierne emulsion models using the storage modulus of the PMMA and PS, and found to be 1.0 and 2.0 mN/m, respectively. The interfacial tension between the PMMA and PS was also calculated from the Flory-Huggins polymer-polymer interaction parameter ($\chi$) and found to be from 0.98 to 1.86 mN/m depending on the molecular weight and composition. Comparing the values of the interfacial tension from the Flory-Huggins polymer-polymer interaction parameter and the values measured by oscillatory rheometer, it is suggested that the interfacial tension of the PMMA-PS blend obtained from the polymer-polymer interaction parameter are in good agreement with the values obtained by rheological measurements.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.146-149
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• 2004

Porous silicon(PS) as an excellent light diffuser can be used as an antireflection layer without other antireflection coating(ARC) materials. PS layers were obtained by electrochemical etching(ECE) anodization of silicon wafers in hydrofluoric acid/ethanol/de-ionized(DI) water solution($HF/EtOH/H_2O$). This technique is based on the selective removal of Si atoms from the sample surface forming a layer of PS with adjustable optical, electrical, and mechanical properties. A PS layer with optimal ARC characteristics was obtained in charge density (Q) of 5.2 $C/cm^2$. The weighted reflectance is reduced from 33 % to 4 % in the wavelength between 400 and 1000 nm. The weighted reflectance with optimized PS layers is much less than that obtained with a commercial SiNx ARC on a potassium hydroxide(KOH) pre-textured multi-crystalline silicon(mc-Si) surface.

• Journal of the Korea Concrete Institute
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• v.13 no.1
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• pp.30-37
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• 2001

Generally, polymer mortar made with unsaturated polyester(UP) resin has a high curing shrinkage. This is an inadequate as repair material and construction products that have been widely used for years recently. To overcome these problems, polymer researchers and engineers have used shrinkage-reducing additives, which are usually specific thermoplastic polymers. The objective of this study is to evaluate the effects of shrinkage-reducing additive on the curing shrinkage and strengths of UP mortar. UP mortars are prepared with expanded polystyrene(EPS) ratio in styrene monomer(SM), (EPS/PS, PS=EPS+SM), and the ratio of total polystyrene resin(PS) to UP resin, (PS/UP). And it is tested for viscosity of UP resin, slump-flow, working life, flexural and compressive strengths, and curing shrinkage tests. From the test results, viscosity of resin for UP mortar increases with increasing PS content. Curing shrinkage of UP mortar is considerably smaller than that of plain UP mortar, nevertheless, reduction in the strengths is not recognized according to adding PS resin. In this study, we can obtain the optimum mix proportions of UP mortar using PS resin which made of waste expanded polystyrene.

• Korea-Australia Rheology Journal
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• v.13 no.2
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• pp.83-87
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• 2001

The morphology and mechanical properties of the blends of a syndiotactic polystyrene (SPS) and poly-styrene-block-poly(ethylene-co-butylene)-block-polystyrene copolymers (SEBS) with various polystyrene block contents are studied. Mechanical properties, especially elongation at break and impact strength (IS), of the blend depend upon the morphology and interfacial adhesion, which in rum are affected by the viscosity ratio of constituent components and the styrene block content in SEBS. The IS of a blend was affected by the combined effect of rubber content and the interfacial adhesion. A maximum IS was found for a blend with the weight fraction of the PS block in an SEBS of 0.18. The IS of blends with smaller weight fractions of the PS block exhibited lower due to poor interfacial adhesion between SPS/SEBS in spite of a larger amount of rubber block. On the other hand, the IS of blends with larger weight fraction of the PS block becomes smaller due to lower amounts of rubber block in spite of better interfacial adhesion.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.13-20
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• 2015

Soda-AQ pulp made from sugarcane bagasse (SCB) and oil palm trunk (OPT) were bleached in element chlorine free (ECF) sequence. Bleached SCB and OPT pulp was achieve higher brightness than 85.0% ISO. Viscosity of SCB bleached pulp and OPT bleached pulp were achieved 18-27 cPs and 18-26 cPs. In 7.8% active chlorine dioxide addition, bleached SCB pulp was shown 88.7% ISO brightness and 20.4 cPs viscosity. And bleached OPT pulp was shown 88.5% ISO brightness and 18.8 cPs viscosity with 7.8% active chlorine dioxide addition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.11
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• pp.963-968
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• 2002

In this work, porous silicon (PS) layer is investigated as a sensing material to detect organic vapors such as ethanol (called alcohol), methanol, and acetone in low concentrations. To do this, PS sensors were fabricated. They have a membrane structure and comb-type electrodes were used to detect the change of electrical resistance effectively. PS layer on Si substrates was formed by anodization in HF solution of 25%. From fabricated sensors, current-voltage (Ⅰ-Ⅴ) curves were measured for gases evaporated from 0.1 to 0.5% organic solution concentrations at 36$\^{C}$. As the result, all curves showed rectifying behavior due to a diode structure between Si and the PS layer. The conductance of most sensors increased largely at high voltage of 5V, but the built-in potential on the measured Ⅰ-Ⅴ curve was lowered inversely by the adsorption effect of the organic vapors with high dipole moment.

• Bulletin of the Korean Mathematical Society
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• v.45 no.3
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• pp.445-456
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• 2008

Let M be a right R-module, G an ordered group and ${\sigma}$ a map from G into the group of automorphisms of R. The conditions under which the Malcev-Neumann module M* ((G)) is a PS module and a p.q.Baer module are investigated in this paper. It is shown that: (1) If $M_R$ is a reduced ${\sigma}$-compatible module, then the Malcev-Neumann module M* ((G)) over a PS-module is also a PS-module; (2) If $M_R$ is a faithful ${\sigma}$-compatible module, then the Malcev-Neumann module M* ((G)) is a p.q.Baer module if and only if the right annihilator of any G-indexed family of cyclic submodules of M in R is generated by an idempotent of R.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.223-223
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• 2009

In this paper, designed and simulated Power Splitter (PS) integrated Mach-Zehnder interferometer (MZI) based planar type optical waveguide devices (which is called here a PS-MZI). The PS-MZI optical waveguide sensor was preceded by a Y-junction, which splits the input power between the sensor, and a reference branch, to minimize the effect of optical power variations. The PS-MZI optical waveguide sensor induced changing phases of the incident beam, which had fallen upon the waveguide through computer simulation, according to the small changes in the index of refraction, thus beam intensity was changed. The waveguide were optimized at a wavelength of 1550 nm and fabricated according to the design rule of 0.45 delta%, which is the difference of refractive index between the core and clad. The fabrication of PS-MZI optical waveguide sensor was performed by a conventional planar lightwave circuit (PLC) fabrication process. The PS-MZI optical waveguide that was fabricated to be applied as a biosensor revealed a low insertion loss and a low polarization-dependent loss. After having etched the over-clad at the sensor part in the MZI optical waveguide that was fabricated, Ti deposition was made on the adhesion layer, and then Au thin-film deposition was carried out thereon. In addition, its optical properties were measured by having changed the index of refraction oil at the sensing part of the MZI. To apply the planar type PS-MZI optical waveguide as a biosensor, a detection test for Staphylococcus aureus was conducted according to changes in concentration, having adopted Ti-alkoxide as ligand. The detection result of the S. aureus by the PS-MZI optical waveguide sensor was possible to the level of $10^1$ CFU/ml.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1533-1541
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• 2016

Samples of doenjang (a fermented soybean paste) were prepared with different types of salts; purified salt (PS), 3-year-aged solar salt (SS3), 1-year-aged solar salt (SS1), and bamboo salt (BS, 3^rd processing product). For starter doenjang samples, selected starters comprising two bacilli, one yeast, and one fungus were inoculated, whereas for non-starter doenjang samples, microorganisms present in rice straw were inoculated after enrichment. The doenjang samples were fermented for 13 weeks at 25℃. During the fermentation period, SS and BS doenjang samples showed higher bacilli counts as well as much lower yeast counts than PS doenjang. At 13 weeks, yeast counts of starter doenjang samples were 7.75, 5.69, 6.08, and 4.74 log CFU/g for PS, SS3, SS1, and BS doenjang, respectively. For non-starter doenjang samples, counts were 7.17, 5.05, 5.92, and 4.54 log CFU/g for PS, SS3, SS1, and BS doenjang, respectively. SS and BS promoted growth of bacilli but inhibited growth of yeasts compared with PS. Debaryomyces hansenii was the dominant yeast in PS doenjang, whereas Candida guilliermondii and Pichia sorbitophila were dominant in SS and BS doenjang. In the sensory evaluation, SS and BS doenjang scored better than PS doenjang. In conclusion, SS and BS seem better than PS for production of high-quality doenjang.

• Asian Journal of Turfgrass Science
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• v.6 no.1
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• pp.11-22
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• 1992

To determine the use of waste materials as root zone soil mixtures for turfgrass culture, the effects of paper mill sludge and briquet ash on physical and chemical properties of soil and growth of turfgrasses were examined. Three turfgrass species of zoysiagrass(Zoysia japonicaSteud.). kentycky bluegrass(Poa pratensis L. 'Ram I') and creeping bentgrass(Agrostis panistris Huds 'Persucross') were cultured in 32cm diameter plastic pots containing various soil mixtures. The basic ingredients used for mixtures included sand(SD), field soil(SL), paper mill sludge(PS), sphagnum peat moss(PM) and briquet ash(BA). Seven combinations using these ingreients were mixed in different percentage by volume as follows: SD+SL+PM(80:10.10), SH+SL+PS(80:10:10), SD-PM(80:20), SD+PS (80:20), SD+BA(80:20), SD+BA+PM(60:20:20) and SD+BA+PS(60:20:20). 1. Paper mill sludge showed pH of 6.6, more than 30% of organic matter content, and higher concentrations of total N, P, k, Ca, Mg and CEC. Bulk density, fild moisture capacity and electrical conductivity of soil mixtures were increased by the comimation of 10~20% PS by volume. 2. Briquet ash showed pH of 8.0, and higher levels of P, k, Ca and Mg than those of field soiks. Bulk density, field moisture capacity and hardenss of soil mixtures were increased but vertical water flow rate and electrical conductivity were decreased by the combination of 20% BA by volume. 3. Phytotoxic effects of PS and BA on growth of turfgrasses were not found. Shoot growth of all three species was higher in soil combination of SD+BA+PS than that of SD+SL+PM added with fertilizer. However, root growth was better in soil mixtures combined with PM. Soil mixtureomposed of 60% SD, 20% BA and 20% PS by volume was most effective on growth of all three species. 4. Paper mill sludge resulted in higher N level in the leaf tissue. The contents of heavy metals such as Cd and Ph did not vary significantly among soil mixtures and species. However, the Mn level was 2~3 times higher in plants growh in mixtures containing PM compared with others, and especially it was higher in creeping bentgrass than other species.