• Elastomers and Composites
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• v.27 no.1
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• pp.20-26
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• 1992

Reactions between chlorinated or brominated poly(isobutylene-isoprene) (CIIR and BIIR, respectively) and 3-mercaptopropyltrimethoxysilane(MPS) were kinetically studied by gas chromatography in solution state. CIIR and BIIR were mixed with MPS and dibutyltin dilaurate as catalyst on roll mill and then the compounds were cured in hot water or atmosphere. From the gas chromatography, reaction order, activation energy, and frequency factor were determined. Crosslinking density and physical properties of moisture-cured CIIR and BIIR were measured. CIIR and BIIR were effectively moisture-cured and physical properties of these rubbers were comparatively good.

• Polymer(Korea)
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• v.39 no.3
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• pp.433-440
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• 2015

Aluminum trihydroxide (ATH) has been commonly employed as a flame retardant for ethylene vinyl acetate (EVA) copolymers. In the present work, ATH was obtained from a recycling process of multi-layer packaging film wastes. EVA/ATH composite samples were prepared using a two roll-mill and flame retardancy of EVA/ATH composites were examined using limiting oxygen index (LOI) and flame retardancy test (UL94). We observed excellent flame retardancy in case of adding 150 phr or more of recycled ATH to EVA. Particle size and specific surface area play crucial roles in LOI value and UL-94 classification of the EVA/ATH composites. Smaller particle size and higher specific surface area of ATH was found out to improve the flame retardancy. Regarding tensile properties, crosslinked EVA/ATH compounds which is practically used for electric cables had similar to or even better tensile property values than the ones without ATH.

• Composites Research
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• v.27 no.5
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• pp.190-195
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• 2014

This paper predicts the complex permittivity of MWNT added epoxy depending on agglomeration by numerical analysis. 1wt% MWNT added epoxy specimen is prepared using 3-roll-mill method and its complex permittivity is measured in X-band (8.2~12.4 GHz) using freespace measurement system. The analytic model is comprised of cube epoxy and perfect sphere agglomeration. The complex permittivity of the agglomeration model is predicted by complex permittivity mixing rule using the measured complex permittivity of epoxy and 1 wt% MWNT added epoxy. Commercial electromagnetic analysis software, CST, is used to obtain S-parameter of the analytic model and MATLAB code is used to calculate complex permittivity from the S-parameter. It is confirmed that the complex permittivity increases when the agglomeration size decreases.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.4
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• pp.307-315
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• 1989

In this paper, we have analyzed the temperature variation trend of a slab on between the process of reheating furnace and the termination of roughing mill process during hot rolling process. 1) cooling by radiation and convection current in the air, 2) plastic deformation heat, 3) cooling by descaling water, 4) cooling by contact with rolling rolls and/or transmitting rolls. For the analysis, the factors have been adopted as the problems of the rolling process to be solved such that we have established an application technique in relation to the determination of boundary conditions on the slab surface. We have presented a procedure for an analysis of the cooling phenomenon treated as a problem of two-dimensional transient heat flow using finite difference equation and suggested techniques of implementing sequentialized rolling tasks in correlation with the procedure. From the result of simulation, it is shown that the difference between calculation value and measurement value is within the range of the industrial measurement error. Also, it is proved that the assumptions, conditions, and properties used in the computer simulation is appropriate by showing that the pattern of a drop in temperature at each rolling event is in accord with real circumstances.

• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.771-776
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• 1997

The various shape of calcium carbonate were prepared. For the preparation of the PP/$CaCO_3$ composite, these synthetic calcium carbonate(cubic, spheric and neddle type) and PP were mixed on a two roll mill and the mixture were pressed into plate. The effect of particle shape in the prepared composite on the crystallization temperature, heat of fusion, size of spherulite and mechanical properities were investigated. It was found that the former four were strongly influenced by that. When, especially, vaterite was mixed with PP, the size of spherulite was smaller and the degree of crystallinity was higher than others. Therefore, the tensile strength and Young's modulus were higher.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.58 no.1
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• pp.67-70
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• 2013

This research study was to develop methods for inhibiting the germination of cotton seeds. Germination rates after heating treatment at $80^{\circ}C$ with 10, 20, 30, 40 min. were 9.3, 9.3, 5.3 and 1.3 percentage, respectively. Heat treatment over $85^{\circ}C$ with 10 min. caused no germination of cotton seeds. Germination was significantly reduced with gamma rays treatment more than 10,000 gy, while the treatment within 2,000-8,000 gy induced less effects. Microwave processing for 30 seconds and 60 seconds inhibit the germination of cotton seed under 8 and 0%, respectively. As a physical treatment, rollmill milling with 1.5, 2, 2.5 mm gap inhibited any germination of cotton seeds. The optimum gap of roll-mill for processing physical cracking was below 51% of the thickness of seed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.966-970
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• 2006

We reported on characteristics of the piezoelectric ceramic-polymer composite for the application of the thick-film speaker. The PVDF-PZT composites were fabricated to incorporate the advantages of both ceramic and polymer with various mixing ratios by 3-roll mill mixer. The composite solutions were coated by the conventional screen-printing method on ITO electrode coated PET (Polyethylene terephthalate) polymer film. After depositing the top-electrode of silver-paste, 4 kV/mm of DC field was applied at $120^{\circ}C$ for 30 min to poling the composite films. The value of $d_{33}$ (piezoelectric charge constant) was increased when the PZT weight percent was increased. The maximum value of the $d_{33}$ was 24 pC/N at 70 wt% PZT. But the $g{33}$ (piezoelectric voltage constant) showed the maximum value of $32mV{\cdot}m/N$ at 65 wt% of PZT powder. The SPL (sound pressure level) of the speaker fabricated with the 65:35 composite film was about 68 dB at 1 kHz.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1363-1372
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• 1992

The effects on lubricity and the anti-seizure property of lubricant according to base oils and extreme pressure additives of sulfur type and phosphorous type in cold rolling were evaluated by a laboratory scale rolling mill, where the contact conditions between work roll and strip are very close to actual cold rolling mill. The important results were obtained as follows : (1) synthetic oil has better effect on lubricity than tallow, (2) lubricant with extreme pressure additives of sulfur type of phosphorous type has better effect than base oil noly, (3) the more amount of extreme pressure additives is, the better effect on lubricity is, (4) sulfur type has better effect on lubricity than phosphorous type and (6) phosphorous type has better effect on anti-seizure property than sulfur type.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.2
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• pp.144-150
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• 2013

A New Ag-pastes were developed for integrating the high efficiency mono-Si solar cell. The pastes were the mixture of 84 wt% Ag, 2 wt% glass frit, 11 wt% solvent of buthyl cabitol acetate, and 3 wt% additives. After fabricating the Ag-pastes by using a 3-roll mill, they were coated on a $SiN_x$/n+/p- stacks of a commercial mono-Si solar cell. And the post-thermal process was also optimized by varying the process conditions of peak temperature. The optimized solar cell efficiency on a 6-inch mono-Si wafer was 18.28%, which was the one of the world best performances. It meaned that the newly developed Ag-paste could be adopted to fabricate a commercial bulk Si solar cell.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.1017-1020
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• 2002

The pure Ti is taken annealing process for one hour at 90$0^{\circ}C$. The pure Ti is sufficient for ASTM B348 Grade2. The rolling mill roll the Ti-8Ta-3Nb(wt%) which became vacuum melting in arc furnace until the length is about 45mm and the thickness is about 6.05mm. Then it is made 6mm$\times$6mm$\times$44mm by wire cutting with EDM and it is made ∮ 6mm by rough cutting with the general purpose lathe. The machining accuracy of implant parts in the dental and medical science are decided by dimension, shpe, straightness, surface roughness. It is difficult to cut for the Ti alloy. It is caused problems of straight degree and surface roughness to the Ti alloy have many cases which length is smaller than diameter in cutting. Total 24 specimens different kind of 4 alloies are used in experiment to gain a cutting property. According to the cutting velocity, cutting depth, cutting temperature, feed and clearance angle experiments are performed. Conclusively it is expected that cutting depth of 0.5mm, feed velocity of 0.07mm/rev and cutting velocity of 80m/min could make a suitable result.