• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.614-619
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• 2005

The water-soluble defoamers were fabricated by the mixing polyol, modified silicon resin, silicon resin and surfactant. For the defoamers, the various properties such as phase-separation time, viscosity and defoamerability were examined. The phase-saparation time of PPG mixtures was found to be PPG 400>PPG 3,000>PPG 1000. When PPG 1000 was mixed, mixtures represented the excellent defoamerability. The phase-saparation time of silicon resin mixtures was TSF-451-350>TSF-451-200>TSF-451-50. As more of high molecular silicon resin was mixed, the resulting mixtues showed reduced defoamerability. When the TSF-451-50 was mixed, the mixture's volume was increased because of the reduction of solubility. The modified silicon resin was smoothly dispersed in water, but the compatibility with PPG was not good. The defoamerability of surfactant was SPAN 20>SPAN 60>SPAN 80. SPAN 80 showed good miscibility for the silicon resin, but not good for YAS 6406 or PPG 1000.

• Journal of Aquaculture
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• v.21 no.4
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• pp.299-303
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• 2008

A 6 and 8-week feeding trial was conducted to determine optimal feeding rate for parrot fish Oplegnathus fasciatus during the low temperature season. To estimate the optimal feeding rate calculated by weight growth rate, one year (mean body weight: 62.7 g) and the two year old parrot fish (mean body weight: 344.7 g) were stocked under low water temperature conditions. The optimal feeding rates in low water temperature condition of $15^{\circ}C$ were calculated as 1.61% of body weight (90% of satiation level) for the one year of 62 g, and calculated as 0.28% of body weight (80% of satiation level) for the two years old fish.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.6
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• pp.258-263
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• 2008

The fine aggregates of below 2 mm size was fabricated using by the vertical furnace in which the aggregates could be sintered at floating state and its physical properties were analyzed. The liquid formed at the surface of specimens sintered at $1200{\sim}l300^{\circ}C$ induced a gas in core to expand so the denser shell and porous core could be produced. The C series specimen fabricated by crushing an extruded body had an irregular shape and sharp edges but those became spheroidized by bloating due to gas expansion inside. The fine aggregates fabricated in this study was as light as floating in the water and had an apparent density of $0.68{\sim}1.08$. The absorption rate was proportioned to a porosity showing that the pores in core was not closed completely. The properties of fine aggregates fabricated in vertical furnace were similar with those of in an electric muffle furnace but the sticking-together phenomenon by surface fusion was not occurred in the vertical furnace. The aggregates fabricated in this study had a little lower impact resistance than that of natural aggregate but satisfied the unit volume weight standard specified in KS.

• Textile Coloration and Finishing
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• v.32 no.2
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• pp.111-120
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• 2020

In this study, lignin/chlorinated poly(vinyl chloride)(CPVC) blended fibers have been produced for the development of low-cost carbon fiber. Carbon fiber manufacturing was accomplished through stabilization and carbonization process. The lignin/CPVC blended fibers were prepared by wet spinning method. Dimethylacetamid e(DMAc) and cychlohexanone in a ratio of 5:1(wt%) was employed as co-solvent. The ratio of lignin/CPVC was prepared at 0/10, 1/9, 2/8, 3/7, 4/6, and 5/5(wt%). The spinning solution was extruded at a rate of 0.1 to 0.4ml/min according to the blending ratio. The speed of the rollers was the same for all ratios(draw ratio=1). Analysis of fiber cross-section by scanning eletron microscopy(SEM) showed that as the lignin ratio increased in the same coagulation bath and distilled water, the pore size of the spinning fiber decreased. Therefore, the highest tensile strength of the blending fibers was 6.3±1.2MPa at the 5/5 ratio. The carbon fiber also showed the best tensile strength of 120.78±2.43MPa at 5/5 ratio.

• Korean Journal of Food Science and Technology
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• v.22 no.4
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• pp.451-455
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• 1990

The extrusion characteristics of pork rind mixed with corn flour were investigated. The blends of pork rind to corn flour in the ratio of 1 : 2, 1 : 1, 2 : 1 and 3 : 1(w/w) were made and each blend was dried up to 5, 10 and 15% moisture content. The blends were extruded by single screw extruder. The extrusion characteristics of each extrudate were as follow. The highest value of expansion ration was attained by mixing pork rind and corn flour in the ratio of 1 : 1, containing 5% moisture content. As the rind content to the corn flour mixture was increased, the bulk density, water absorption index, breaking stregth and redness, of the extradate increased, but the lightness and yellowness decreased. It was concluded that a high quality snack food could by produced by extrusion-cooking the mixture of pork rind and corn flour.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.95-105
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• 2002

In order to reduce the lead-time and cost, the technology of rapid prototyping (RP) has been widely used. However, RP technologies have disadvantageous characteristics according to their working principle: low building speed, high cost for introduction and maintenance of RP apparatus, stair-stepped surface and additional post processing. A new rapid prototyping process, as a transfer type of Variable Lamination Manufacturing by using expandable polystyrene room (VLM-ST), has been developed to reduce building lime. apparatus cost including the introduction and the maintenance and additional post-processing. The objective of this study is to propose a VLM-ST process and to develop an apparatus for implementation of the process. Design criteria of the apparatus are defined and the techniques arc proposed to satisfy the design criterion. In order to examine the efficiency and applicability of the developed process, various three-dimensional shapes, such as a world-cup logo. a knob shape, an extruded cross, a twisted shape, a character, Son-o-kong. a helical gear shaped and a scissor shape are fabricated on the apparatus in which unit shape layer (USL) was generated to build up each layer.

• Journal of the Korean Institute of Gas
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• v.13 no.4
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• pp.22-26
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• 2009

In this paper, the displacement behavior and strain energy density characteristics of a safety helmet with various corrugation dampers has been analyzed based on the finite element analysis. The safety helmet is to protect impact forces and to absorb the impact energy. Three different helmet models with a corrugation damper have been compared as functions of the displacement and strain energy density characteristics when the maximum external impulsive force is imposed on the summit of the helmet. The computed FEM results show that the extruded corrugation damper is very useful to increase the damping effect of the helmet. This study indicates that the round corrugation damper may absorb the transferred impact energy successfully. Thus, this paper recommends round and long corrugation damper on the lower part of the helmet as a new design element.

• Journal of Powder Materials
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• v.10 no.6
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• pp.406-414
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• 2003

In order to produce good wear resistance powder metallurgy Al-Si alloys with high strength, addition of glass forming elements of Ni and Ce in $Al_{81}$Si$_{19}$ alloy was examined using SEM, TEM, tensile strength and wear testing. The solubility of Si in aluminum increased with increasing Ni and Ce contents for rapidly solidified powders. These bulk alloys consist of a mixed structure in which fine Si particles with a particle size below 500 nm and very fine A1$_3$Ni, A1$_3$Ce compounds with a particle size below 200 nm are homogeneously dispersed in aluminum matrix with a grain size below 600 nm. The tensile strength at room temperature for $Al_{81}$Si$_{19}$, $Al_{78}$Si$_{19}$Ni$_2$Ce$_{0.5}$, and $Al_{76}$Si$_{19}$Ni$_4$Ce$_1$ bulk alloys extruded at 674 K and ratio of 10 : 1 is 281,521, and 668 ㎫ respectively. Especially, $Al_{73}$Si$_{19}$Ni$_{7}$Ce$_1$ bulk alloy had a high tensile strength of 730 ㎫. These bulk alloys are good wear-resistance bel ter than commercial I/M 390-T6. Specially, attactability for counterpart is very little, about 15 times less than that of the I/M 390-T6. The structural refinement by adding glass forming elements such as Ni and Ce to hyper eutectic $Al_{81}$Si$_{19}$ alloy is concluded to be effective as a structural modification method.d.tion method.

• Polymer(Korea)
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• v.37 no.3
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• pp.405-410
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• 2013

The effect of styrene-ethylene/butylene-styrene (SEBS) on the blend of polyphenylene sulfide (PPS) and polyethylene terephthalate (PET) was investigated. The blends were extruded by a single screw extruder equipped with a Maddock mixing screw, and their molded properties were examined. After the binary blends were prepared on the whole compositions of PPS/PET (80/20, 60/40, 40/60, 20/80), the thermal, rheological, mechanical properties and morphology of the blends were analyzed. The results showed the significant decline in the properties of the blends owing to the incompatibility between PPS and PET phases. As a basic blend composition, the PPS/PET (40/60) blend was selected by considering cost efficiency. To this basic blend, SEBS was added as a compatibilizer. With increasing SEBS addition, the mechanical properties were improved. From the domain size reduction observed in morphology, it might be due to the enhancement of compatibility between linear PPS and PET phases by addition of SEBS.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.662-667
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• 2009

Porous SiC candle filter preforms were fabricated by extrusion and ramming process. To fabricate SiC candle filter preform, commercially available 85 ${\mu}m\;{\alpha}-$-SiC powder and 44 ${\mu}m$ mullite, CaC$O_3$ powder were used as the starting materials. The candle type preforms were fabricated by vacuum extrusion and ramming process, and sintered at $1400{^{\circ}C}$ 2 h in air atmosphere. The effect of forming method on porosity, density, strength (flexural and compressive strength) and microstructure was investigated. Also, corrosion test of the sintered candle filter specimens as forming method was performed at $600{^{\circ}C}$ in IGCC syngas atmosphere. The sintered SiC filter which was formed by ramming process has more higher density and exhibit higher strength than extruded filter. Its maximum density and 3-point bending strength were 2.00 g/$cm^3$ and 45 MPa, respectively.