• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.79-88
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• 1999

The stability and performance (peel strength) of the acrylic copolymer and various modified rosin systems were investigated. The peel strength was measured over a wide range of scaling rates, and the influence of the viscoelasticity of the PSA(pressure sensitive adhesive) was considered. In the case of miscible systems, the peak of peel strength (PSA performance) over wide peel rates was changed and modified systematically with increasing glass transition temperature of the blends. The peak of the peel strength for blended systems shifts toward the lower rate side as glass transition temperature ($T_g$) of the blend increased. The influence of esterification of the rosin on performance and stability against deterioration was greatly modified by blending with rosin of glycerol ester and rosin pentaerythritol ester. The failure mode of the blend varies with the combination with acrylic copolymer and modified rosin, and cohesive failure was found at a lower peel rate while interfacial failure was found at a high peel rate. A few systems where a single Tg could be measured, despite the fact that two phases were observed microscopically, were detected.

• Structural Engineering and Mechanics
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• v.8 no.1
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• pp.103-118
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• 1999

The structural integrity of the reactor pressure vessel under pressurized thermal shock (PTS) is evaluated in this study. For given material properties and transient histories such as temperature and pressure, the stress distribution is found and stress intensity factors are obtained for a wide range of crack sizes. The stress intensity factors are compared with the fracture toughness to check if cracking is expected to occur during the transient. A round robin problem of the PTS during a small break loss of coolant transient has been analyzed as a part of the international comparative assessment study, and the evaluation results are discussed. The maximum allowable nil-ductility transition temperatures are determined for various crack sizes.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.36-40
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• 2002

The order-disorder phase transition of (Fe/sub 0.61/Ni/sub 0.39/)₃V alloy that is annealed at various temperatures and time conditions was sty(lied with the examination of long-range order parameter(S) by using neutron diffraction method. As a result, the structure of the sample annealed at 680℃ for 94 h was not changed; that is, it existed iii perfect disordered state and showed face-centered cubic structure. Otherwise, samples which were annealed at temperature below 640℃ showed the value of long-range order parameter with 0 < S < 1 and phase transition into simple cubic structure partly. It was found that the annealed sample at 465℃ for 144 h is the most approximated to the thermal equilibrium state from the S-T/T/sub c/ related equation of Cowley.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.8-19
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• 2016

This paper investigates the effects of inlet turbulence conditions and near-wall treatment methods on the heat transfer prediction of gas turbine vanes within the range of engine relevant turbulence conditions. The two near-wall treatment methods, the wall-function and low-Reynolds number method, were combined with the SST and ${\omega}RSM$ turbulence model. Additionally, the RNG $k-{\varepsilon}$, SSG RSM, and $SST_+{\gamma}-Re_{\theta}$ transition model were adopted for the purpose of comparison. All computations were conducted using a commercial CFD code, CFX, considering a three-dimensional, steady, compressible flow. The conjugate heat transfer method was applied to all simulation cases with internally cooled NASA turbine vanes. The CFD results at mid-span were compared with the measured data under different inlet turbulence conditions. In the SST solutions, on the pressure side, both the wall-function and low-Reynolds number method exhibited a reasonable agreement with the measured data. On the suction side, however, both wall-function and low-Reynolds number method failed to predict the variations of heat transfer coefficient and temperature caused by boundary layer flow transition. In the ${\omega}RSM$ results, the wall-function showed reasonable predictions for both the heat transfer coefficient and temperature variations including flow transition onset on suction side, but, low-Reynolds methods did not properly capture the variation of the heat transfer coefficient. The $SST_+{\gamma}-Re_{\theta}$ transition model showed variation of the heat transfer coefficient on the transition regions, but did not capture the proper transition onset location, and was found to be much more sensitive to the inlet turbulence length scale. Overall, the Reynolds stress model and wall function configuration showed the reasonable predictions in presented cases.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1496-1499
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• 2001

Optical and electrical properties of the $In_2Se_3$ single crystals grown by use of the Bridgman technique were examined in the transition temperature range between $\alpha$-phase and $\beta$-phase. $In_2Se_3$ single crystal has the rhombohedral structure and lattice constants are a=4.025 $\AA$, c=28.771 $\AA$ in C-axis. The transition temperatures of the stoichiometric $In_2Se_3$ single crystal is $10^{-2}{\Omega}cm^{-1}$ according to the specimens. However it varies rapidly in the transition region.

• Transactions of the Korean Society of Mechanical Engineers
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• v.4 no.4
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• pp.152-159
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• 1980

The temperature and the grain boundary precipitation have the great influence on the low-cycle fatigue behavior of austenite stainless steel at elevated temperature. For the purpose of investigating the mechanism concerning the change of fatigue micro crack mode in SUS 316 under various conditions low-cycle fatigue test was carried out at the elevated temperature 600.deg.C, plastic strain range 2% and constant strain rate .5c.p.m. A special attention is given to the observation of intergranular crack initiation. The results obtained are summarized as follows. The low-cycle fatigue behavior of SUS 316 at 600.deg.C is affected by transition of crack initiation mode from intergranular to transgranular. The transition is due to the aging effect, which is caused by grain boundary precipitations of Cr$\_$23/C$\_$6/. Since the intergranular crack initiation is brought about by the grain boundary sliding, the transgranular crack initiates in case that the strengthening of grain boundary due to the precipitation of Cr$\_$23/C$\_$6/ carbides takes place ahead of the intergranular crack initiation.

• Journal of Forest and Environmental Science
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• v.32 no.4
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• pp.323-328
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• 2016

Thermal stability and rheological behaviors of Ricinodendron heudelotii wood were investigated. Thermogravimetric analysis conducted at a heating rate of $10^{\circ}C/min$ from 20 to $600^{\circ}C$ in a nitrogen atmosphere indicated that there was no variation in the decomposition of the onset and final temperature for all the polymers. The thermal behaviours were investigated at a temperature range from 130 to $0^{\circ}C$ at $3^{\circ}C/min$, multi-frequencies of 0.1-10 Hz using dynamic mechanical analysis. N-methyl-2-pyrolidone saturated specimens were tested while submerged under the same solvent. Polymers decomposition pattern during thermogravimetric analysis are similar in the radial position of the wood. The glass transition temperature (Tg) of R. heudelotii is $45{\pm}1^{\circ}C$ at 0.1 Hz. The Tg differs from the innerwood to outerwood. The Tg showed that N-methyl-2-pyrolidone saturated R. heudelotii would require low energy consumption during chemi-thermomechanical pulping.

• Bulletin of the Korean Chemical Society
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• v.18 no.10
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• pp.1105-1108
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• 1997

The new amorphous intermetallic compounds, M3(AsTe3)2: M=Cr, Co, Fe, were synthesized by the precipitation reaction of the Zintl anion AsTe33- with the divalent transition metal halides in aqueous solution and analyzed by EDS equipped with SEM and PIXE. The empirical formula of the specimens was found to be Fe3.0As1.8Te5.9, Co3.0As2.1Te6.5, and Cr3.0As2.0Te6.9 by the quantitative elemental analysis. The dc specific resistivity of the materials was measured as a function of temperature in the range from 20 to 300 K, in which their resistivity of Cr3(AsTe3)2 was largely dependent on temperature, while those of Co3(AsTe3)2 and Fe3(AsTe3)2 were only slightly dependent on temperature. To characterize the spin glass state of the specimens, the ac and dc magnetic susceptibility were measured and it was found that Co3(AsTe3)2 and Fe3(AsTe3)2 undergo a transition to a spin glass state at 6 K and 38 K, respectively. Magnetization data are reported as both thermal remanent magnetization (TRM) and isothermal remanent magnetization (IRM) as a function of magnetizing field and temperature.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.849-854
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• 2003

Temperature dependent thermoelectric power (TEP) of La$_{2.1}$ Sr$_{1.9}$ Mn$_3$O$_{10}$ system has been studied in the temperature range 80-373 K. In the low temperature ferromagnetic regime, TEP (S) follows an expression of formS＝S$_{0}$ ＋S$_{1.5}$ T$^{1.5}$ ＋S$_4$T$^4$ over the wide range of temperature. The broad peak below the ferromagnetic transition and complicated temperature dependence of S may be understood on the basis of electron-magnon scattering as predicted for an itinerant ferromagnet. High temperature TEP data can be well fitted with Mott's small polaron hopping model.

• Fashion & Textile Research Journal
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• v.24 no.6
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• pp.812-824
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• 2022

This study proposes to develop a 3D printed re-entrant(RE) strip by shape memory thermoplastic polyurethane that can be deformed and recovered by thermal stimulation. The most suitable 3D printing infill density condition and temperature condition during shape recovery for mechanical behavior were confirmed. As the poisson's ratio indicated, the higher the recovery temperature, the closer the poisson's ratio to zero and the better the auxetic properties. After recovery testing for five minutes, it appeared that the shape recovery ratio was the highest at 70℃. The temperature range when the shape recovery ratio appeared to be more than 90% was a recovery temperature of more than 50℃ and 60℃ when deformed under a constant load of 100 gf and 300 gf, respectively. This indicated that further deformation occurred after maximum recovery when recovered at a temperature of 80℃, which is above the glass transition temperature range. As for REstrip by infill density, a shape recovery properties of 100% was superior than 50%. Additionally, as the re-entrant structure exhibited a shape recovery ratio of more than 90%, and exhibited auxetic properties. It was confirmed that the infill density condition of 100% and the temperature condition of 70℃ are suitable for REstrips for applying the actuator.