• Textile Coloration and Finishing
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• v.16 no.4
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• pp.1-9
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• 2004

In recent, development of nano fiber has been one of the most active subjects in the world. Nano fiber is defined as a ultra fine yarn with a diameter unit of $10-100\times10^{-9}meter$, which is possible to be produced by an electro-spinning technology. In this study, physical characteristics and dyeing properties of nylon 66 nano fiber were investigated. Nylon 66 nano fiber was dyed with levelling type acid dyes. X-ray diffraction method and DSC analysis were used for the measurement of the degree of crystallization. Analysis of amino end groups was also performed in order to examine a relationship between number of amino groups and its dyeing property as well as water absorption behavior. The maximum exhaustion % of dyes and dyeing rate under various dyeing conditions, such as dyeing temperature and pH in dye bath, along with build-up properties for 2 acid dyes were evaluated. It was found that the degree of crystallization of nano fiber was smaller than that of regular fiber, and amino end groups of nano fiber were less than regular fiber. Half dyeing time of nano fiber was shorter than regular fiber because of the bigger specific surface area. Effect of pH on exhaustion % was small in case of nano fiber. Exhaustion of nano fiber increased with higher concentration of dye.

• Textile Coloration and Finishing
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• v.27 no.1
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• pp.11-17
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• 2015

Recently, super fiber reinforced composite materials are widely used in many industries due to high mechanical properties. In this study, 2 different types of composite materials were manufactured in order to compare their mechanical properties. Carbon and Aramid fibers were used for reinforcement materials and Bisphenol-A type epoxy resin was for matrix. Two kinds of fiber-reinforced materials were manufactured by RIM(Resin Injection Molding) method. Before manufacturing composite materials, the optimal manufacturing and curing process condition were established and the ratio of reinforcement to epoxy resin was discussed. FT-IR analysis was conducted to clarify the structure of epoxy resin. Thermal and mechanical property test were also carried out. The cross-section of composite materials was observed using a scanning electron microscope(SEM).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.749-754
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• 2008

A large number of studies on the various characteristics of epoxy-layered silicate nanocomposites, such as electric and mechanical, morphology have been conducted and contributed to improve their characteristics. However, studies on the effects of its thermal conductivities in the thermal properties are not enough, even though there are some excellent evaluations for its insulation performances. Thermal properties will cause thermal degradation and significantly affect the reliability of these epoxy-layered silicate nanocomposites. In the results of the analysis of epoxy-layered silicate nanocomposites $T_g$ for various types of organoclays (10A, 15A, 20A, 30B, and 93A), it showed an excellent thermal property of 10A. Also, it represented low values in storage modulus and mechanical Tan (Delta) at a high temperature section 140$^{\circ}C$ and excellent thermal properties due to its movement to the high temperature section in the case of the property of 10A in the measurement of DMA elastics and mechanical losses. In the results of the measurement of thermal conductivities, power ultrasonic applications represented a significant increase in thermal conductivities in the case of the applications of power ultrasonic and planetary centrifugal mixers. Based on these results, it is necessary to perform related studies because it can be applied as useful materials for future power facilities applications in mold and impregnate insulation.

• Macromolecular Research
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• v.14 no.6
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• pp.640-645
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• 2006

Polyethylene of bimodal molecular weight distribution was irradiated with an electron beam. The thermal and mechanical properties were examined by DSC, small and wide angle X-ray scattering and static tensile test according to the crystal morphology of the irradiated samples. The crystal morphology change upon irradiation, as revealed by wide angle X-ray scattering, correlated well with the changes in melting enthalpy, whereas the lamellar thickness and the amorphous gap thickness remained virtually unchanged at irradiation doses up to 500 kGy. Crosslinks in the crystal domains became evident at an energy level of 250 kGy, resulting in reduced crystallinity and crystal size of the (110) and (200) planes. The samples became stiff and brittle with increased irradiation dose, which seem to be more relevant to the amount of cross links than the crystal morphology changes.

• Textile Coloration and Finishing
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• v.26 no.1
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• pp.32-38
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• 2014

There has been increasing demand to the eco-friendly materials such as phytoncide which is extracted to plants in the textile industry, recently. It is interesting that alginic acid sodium salt(Alg-Na) is used to eco-friendly binder for the functional capsule finishing. In this study, we made PEO/Alg-Na blend solutions of various ratio and observed the changing binding property of the blend solutions according to PEO contents through FT-IR, DSC, contact angle, peel strength, etc. The viscosity of Alg-Na/PEO blend solutions increased with increase of contents and the viscosity quickly increased with increase of PEO content in Alg-Na 5% content, specially. It is shown that the hydrogen bond peak by blend of Alg-Na and PEO found through FT-IR analysis but the peak decreased in PEO above 60% content. And the peel strength was predominant in PEO 50% ratio.

• Journal of the Korean Society for Heat Treatment
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• v.22 no.6
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• pp.368-374
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• 2009

Nickel titanium shape memory alloys (NiTi) have been investigated for applications in the biomedical industry. However, little is known about the influences of surface modifications on the propertise of these alloys. The effect of electropolishing and heat treatments was found to exhibit significant surface roughness. Change of phase was B2, r-phase and B19' by heat treatments. In this study, effect of the electropolishing conditions on surface roughness is investigated in Ni-Ti alloys (Nitinol). Variation in phases with heat treatment temperature is investigated for a Ni-Ti alloy by X-ray diffraction and DSC. Characteristic of the microstructure have been observed by SEM. Surface roughness have been measured by AFM. The results clearly show that significant different in surface property to heat treated at $500^{\circ}C$ (R-phase). $TiO_2$ phases preciritated all of the specimens. It is not good effect of surface roughness because made to surface relief. The surface roughness appears to be important in the property of Ni-Ti alloys for biomedical applications.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.183-188
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• 2012

A blue phosphorescent $Ir(dfpypy)_3$ (dfpypy:fluorinated pyridine-pyridine ligand) complex with meridional configuration has been synthesized by newly developed effective method and its solid state structure and photoluminescence are characterized. For this complex, mer-$Ir(dfpypy)_3$, the glass-transition and decomposition temperatures appear at $160^{\circ}C$ and $384^{\circ}C$ respectively in TGA and DSC experiments, which indicates that this complex has high thermal stability. In a crystalline structure, an average Ir-C bond length of mer-$Ir(dfpypy)_3$ is slightly longer than that of fac-$Ir(dfpypy)_3$, which assumed to be due to the weak trans-influence. The absorption and emission spectra are observed more red-shifted in mer-$Ir(dfpypy)_3$ than fac-$Ir(dfpypy)_3$. In addition, the former is readily oxidized than the latter in electrochemical behavior.

• Food Engineering Progress
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• v.15 no.2
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• pp.169-174
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• 2011

This study was performed to analyze the effects of ultra fine pulverization (UFP) on the physicochemical properties of sweet potato starch (SPS). The average diameter and specific surface area of the SPS was decreased from 22.94 to 10.25 $\mu$m and from 0.879 to 1.909 $m^2$ /g throughout UFP, respectively, and the damaged starch content was increased from 13.7 to 99.2%. The pulverized sweet potato starch (PSPS) had higher swelling power, solubility, and transmittance values than the SPS. X-ray diffractograms revealed that the SPS had a C-type pattern, which disappeared in PSPS. The rapid visco analysis (RVA) characteristics, peak viscosity, break down, and set back of SPS ceased to exist in PSPS. According to differential scanning calorimetry (DSC) curves, the peak temperature ($T_p$) and gelatinization enthalpy ($\Delta$E) of SPS were $71.95^{\circ}C$ and 10.40 J/g, respectively, while these remained undetected in PSPS. The enzymatic digestibilities of SPS and PSPS were 61.7 and 84.7%, respectively.

• The Korean Journal of Food And Nutrition
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• v.32 no.4
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• pp.304-311
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• 2019

Ohmic heating is a heating method based on the principle when an electrical current passes through food. Since this method is internal, electrical current damage occurred during heating treatment. The results of ohmic heated starch's external structure, X-ray diffraction, DSC analysis and RVA were differed from those of conventional heating at the same temperature. Several starches changed more rigid by structure re-aggregation. This change in starch was caused by change of physical, chemical, rheological property. The rheology of ohmic heated potato and corn starch of different heated methods were compared with chemically modified starch. After gelatinization, sample starch suspension (2%, 3%) measured flow curves by rheometer. Cross-linked chemically modified starch's shear stress was decreased with degree of substitution reversibly. Ohmic heated more dramatic, at $60^{\circ}C$. Potato starch's shear stress was less than commercial high cross-linked modified starch. Flow curves of potato starches measured at $4^{\circ}C$, $10^{\circ}C$, $20^{\circ}C$. Showed that Ohmic heated potato starch's shear stress ranging between $4^{\circ}C$ and $20^{\circ}C$ was narrower than modified starch. According to this study, ohmic heated potato starch can be used by decreasing viscosity agent like cross-linked modified starch.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.215-217
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• 2008

Crystallization behavior of the bulk metallic glass (BMG) during compression and tension was studied in the supercooled liquid region (SLR). Rod samples of the BMG alloy were produced by consolidating gas atomized powders of $Cu_{54}Zr_{22}Ti_{18}Ni_6$ using spark plasma sintering. The crystallization behavior in these samples was examined by tackling changes in thermal property during heating the samples in DSC. The present BMG alloy was firstly decomposed and then crystallized during annealing in the SLR. The phase decomposition from the original amorphous phase was retarded by the compressive stress, while it was accelerated by the tensile stress.