• Korea-Australia Rheology Journal
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• v.12 no.3_4
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• pp.181-186
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• 2000

Rheological Properties of polypropylenes having different molecular structures (linear polypropylene (PPL) and branched one (PPB)) were studied. Both the extensional flow and oscillatory shear flow properties were checked. Especially, the melt strength of polypropylenes having various shear history were investigated by using in-house-made Rheometer (called SMER). Compared to linear polypropylene, the branched polypropylene shows enhanced melt strength during extensional flow due to the retarded relaxation of molecules. When the slope of melt tension was plotted against take up speed of melt strand, the characteristic peak was observed in case of branched polypropylene, while the linear polypropylene shows only monotonously decreasing pattern. This entanglement was partially disrupted by physical forces such as shear during melt extrusion. However, the melt strength of PPB after multiple extrusion is still higher than PPL, implying the loss of elasticity during multiple extrusion is not so comprehensive. On dynamic experiments, PPB shows typical shear thinning behavior and the tangent delta of PPB is lower than PPL, reflecting high elasticity of PPB.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.3
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• pp.276-280
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• 1991

The quality changes of brown rice during storage were determined by the method of quantitative analysis of n-hexanal, amylogram, texture and volume expansion. The qualities of stored brown rice were also analyzed with sensory evaluation of cooked milled rice obtained from brown rice, n-Hexanal content, peak viscosity and total setback of brown rice flour pastes increased substantially with the increased of storage period at 35$^{\circ}C$. Up to 10 months of storage at 35$^{\circ}C$, stale flavor obtained by a sensory method markedly increased, but stickiness decreased. The scores of overall preference were in good agreement with those of stale flavor (r=-0.98) and sticky texture (r=0.98). The correlation coefficient between stale flavor obtained by a sensory method and instrumetal analysis for stored brown rice was r=0.97.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.144-146
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• 2002

The latest development flow of MCCB(Molded Case Circuit Breaker) is largely separated from which are high capability of interrupting compact of size and multi-ability in functions. As follow of development of industrial system. MCCB which are including communication function and having a ultimate interrupting capability is required in electrical system. to attain an effective limitation of the peak let-through current and the let-through energy, the arc has to move rapidly off the contacts and has to increase the arc voltage which mainly effect to interrupt. In this paper. we made high performance circuit breaker which including current limiting unit which is attached to the main which is simulated by CAE tool that are repulsion force and mechanical dynamics after that we tested and finally selected optimized for circuit breaker.

• Publications of The Korean Astronomical Society
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• v.11 no.1
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• pp.91-107
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• 1996

We determine analytically the onset of thin-shell formation time of fast wind bubble with power-law energy injection $E_{in}=E_0t^s$, and power-law ambient density structure, ${\rho}_0(r)={\bar{\rho}}(r/{\bar{r}})^{-{\omega}}$. Thin-shell formation time, $t_{sf}$ can be estimated by minimizing the total time elapsed before the complete cooling of shocked gas. For uniform medium (${\omega}=0$) and constant energy injection (s = 1), the onset of shell formation is found to be at $t_{sf}=5.2{\times}10^3yr$, which agrees Quite well with the results of FCT 1D numerical calculation. We solve the line transfer problem with previous result derived by numerical calculation in order to calculate line profile of [OIII] (${\lambda}=5007{\AA}$) forbidden line. In general, radiative outer shell causes the formation of double peaked line profile. Each peak corresponds to approaching and receeding shells with large velocities. Our line profiles show good agreements with observation of expanding shell structure.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.322-324
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• 2003

Leaf C:N ratio is a new factor in the field of biochemical inversion with hyperspectral data. Effects of common-used spectral transformations including log(R), log(1/R), 1/R, etc. from 400nm to 2490nm on its inversion are compared. Results show that their effects on statistical modeling are not apparent. Continuum removal is used on original reflectance in the range of 2030nm to 2220nm, in which exists an apparent absorption peak due to cellulose, lignin, protein, etc. The effect is distinctive and tends to improve the precision of C:N ratio inversion. Further, it is a robust and physically based transformation.

• Journal of the Korean Society for Railway
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• v.7 no.1
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• pp.55-59
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• 2004

Composite materials were used widely due to merit of light weight, low maintenance cost and easy installation. But it is the cause of enormous casualties to men and properties because of weak about the fire. Particularly, it is more serious in case of subway train installed composite materials. For this reason, experimental comparison has been done fur measuring heat release rate(H.R.R) and smoke production rate(S.P.R) of interior panels of electric motor car using cone calorimeter. A high radiative heat flux of 50kW/㎡ was used to bum out all materials and to simulate the condition of fully developed fire case in the tests. It was observed that Heat Release Rate and Smoke Production Rate curves were dependent on the kinds of the interior materials. From the heat release rate curves, the sustained ignition time, peak heat release rate and total heat release rate were deduced, These data are useful in classifying the materials by calculating two parameters describing the possibility to flashover.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.7-10
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• 2003

Samsung SDI has developed a full color 5.0" WVGA AMOLED display with top emission and a super fine pitch of 0.1365mm(l86ppi), the world's highest resolution OLED display ever reported to date. Scan driver circuits and demux circuit were integrated into the display panel, using low temperature poly-Si TFT CMOS technology, and data driver circuit were mounted using COG chips. Peak luminescence was greater than 300cd/ $m^2$ with power consumption of 500mW with 30% of the pixels on illuminated.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.4
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• pp.682-689
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• 1996

A preparative method has been proposed for obtaining chitosan products which have a desired degree of deacetylation (DD, %) without much decrease in molecular weight. Deacetylation was prepared by two methods. The method I which was proposed by Domard etc. was that DMSO/thiophenol was used repeatedly only during the deacetylation, the method II was that DMSO/thiophenol was used after the alkali treatment. Then, effective deacetylation was performed by the method ll. To determine the degree of deacetylation, potentiometric titration method was adopted. According to the increase of DD, the viscosity average moleclar weght $(\overline{M\upsilon}$) and the DP of the chitosan products were decreased. The intensity of FT-lR peak appeared at $1655cm^{-1}, which was characteristic peak of amide I (Nacetyl secondary amide group), was gradually decreased with deacetylation. X-ray analysis showed that the lattice-spacing in the chitosan film increased with the degree of deacetylation, but the difference of the transparency of the chitosan products was not diverged significantly.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.783-788
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• 2007

An advantage to the extrusion of raw potatoes is a reduction in the energy input required to process potato products; however, the effects of extrusion on the properties of raw potato have not been studied. The purposes of this study were to develop a workable extrusion process for raw potato and to study the effects of extrusion conditions on the pasting properties of extruded potato products. The peak viscosity, final viscosity, pasting temperature, water solubility index, and water absorption index of pressed and pressed-dried potato extrudates decreased as die exit temperature increased, whereas they did not change as screw speed increased. The peak viscosity, final viscosity, and water solubility of steam-cooked potato products decreased with extrusion processing; however, they did not change with increasing die exit temperature and screw speed. Potato products with different degrees of depolymerization of extruded potato starch, depending on die exit temperature, were produced from raw potatoes.

• Journal of the Korean Society for Heat Treatment
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• v.26 no.4
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• pp.185-190
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• 2013

Influence of solution treatment (T4) and peak-aging (T6) on damping capacity was investigated in permanent-mold cast Mg-3%Nd alloy. In as-cast state, the microstructure was characterized by eutectic $Mg_{12}Nd$ intermetallic phase network in the intergranular region. T4 treatment resulted in a dissolution of the eutectic particles, but small amount of the particles still remained in the microstructure. After T6 treatment, nano-sized ${\beta}^{\prime}(Mg_{12}Nd)$ particles were precipitated within the matrix. T4 microstructure showed higher damping capacity than as-cast and T6 ones. In view of the microstructural features, this may well be associated with the dissolution of second-phase particles which play a role in pinning the dislocations acting as a damping source.