• Structural Engineering and Mechanics
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• v.46 no.6
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• pp.827-842
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• 2013

In this paper, the wave propagation in generalized thermo elastic plate immersed in fluid is studied based on the Lord-Shulman (LS) and Green-Lindsay (GL) generalized two dimensional theory of thermo elasticity. Two displacement potential functions are introduced to uncouple the equations of motion. The frequency equations that include the interaction between the plate and fluid are obtained by the perfect-slip boundary conditions using the Bessel function solutions. The numerical calculations are carried out for the material Zinc and the computed non-dimensional frequency, phase velocity and attenuation coefficient are plotted as the dispersion curves for the plate with thermally insulated and isothermal boundaries. The wave characteristics are found to be more stable and realistic in the presence of thermal relaxation times and the fluid interaction.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.133-136
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• 2007

In this work, 3-dimensional, non-isothermal numerical simulation was performed to analyse the effects of contact resistance and electric conductivity of GDL on the fuel cell performance. For numerical simulation contact resistance of Carbon and Stainless steel was measured. The simulation results reveal that 10 times change of electric conductivity leads only 6.5% decrease of PEMFC performance. But stainless steel which has high contact resistance decrease fuel cell performance over 25% at a high current density region than carbon. This results show that suitable Surface treatment technology is needed for metal bipolar plate, especially stainless steel.

• Journal of the Korean Society of Tobacco Science
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• v.5 no.2
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• pp.55-62
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• 1983

Four of non- isothermal methods evaluating kinetics have been studied by using differential scanning calorimetry (DSC) and thermogravimetry (TG) and applied for kinetics of the thermal decomposition of cellulose. It is concluded that the heating evolution methods with DSC and approximative methods with TC can lead to satisfactory kinetic analysis. Results calculating the reacting order and the activation energy of cellulose decomposition were 1/2 order and 42kcaB/mol, respectively.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.73.1-73.1
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• 2010

We use three-dimensional hydrodynamic simulations to investigate the characteristics of turbulence driven in rotating, vertically-stratified disk. Our models are isothermal, and local in the in-plane direction while global in the vertical direction. We allow localized regions with density larger than the threshold value to explode and inject kinetic energy to the surrounding medium in the real space rather than Fourier space, mimicking supernova explosions thought to be the dominant turbulence source. This work extends our previous study where we studied turbulence in a non-rotating, uniform environment. We find that the galaxy rotation does not make a significant difference in the turbulence level at saturation, since the associated shear velocity is much smaller than the explosion velocity. We analyze the properties of turbulence in our models and compare them with those from the uniform-density models. We also discuss the astrophysical implication of our findings.

• The Korean Journal of Rheology
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• v.6 no.1
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• pp.41-48
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• 1994

비뉴톤 유체내에서 이동하는 섬유들과 대분자들은 경우에 따라 일정한 길이와 직경 을 갖는 원통형 물체로 간주될 수 있으므로 유체내에서 이들의 운동을 효과적으로 제어하기 위해서는 비뉴톤 유체내에서 이동하는 원통형 물체들의 길이비와 직경비에 의한 항력계수의 영향을 조사할 필요가 있다. 이러한 사실에 근거하여 원통형 물체의 길이비와 직경비 변화 가 물체의 항력계수비와 직경비를 기준으로한 항력계수비들은 작업유체로 사용된 일반화된 뉴톤 유체와 점탄성유체내에서 이동하는 원통형 물체들의 길이비와 직경비가 증가함에 따라 감소했다. 원통형 물체의 직경비가 0.007에서 0.029까지 변하고 길이비가 10에서 130까지 변 하는 경우 점탄성용액내에서의 항력계수비의 감소율은 일반화된 뉴톤 유체내에서의 항력감 소비의 감소율 보다 10배 내지 30배까지 더컸다. 또한 모든 작업유체에서 원통형 물체들의 항력계수비들은 Reynolds수가 증가함에 따라 감소됐다.

• Korea-Australia Rheology Journal
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• v.20 no.3
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• pp.153-164
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• 2008

Modeling and experiments of three electrospinning systems have been presented and they are i) axisymmetric instabilities in electrospinning of various polymeric solutions, ii) non-isothermal modeling of polymer melt electrospinning, and iii) control of nanoparticle distribution and location via confined self-assembly of block copolymers during electrospinning. It has been demonstrated that predicted simulations are in good agreement with corresponding electro spinning experiments, and theoretical analysis provides fundamental understanding of phenomena that take place during electrospinning of various polymeric liquids.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.152-159
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• 1999

This study is to investigate the effects of warm deep drawing with aluminum sheets of A1050-H16 and A5020-H32 for improving deep drawability. Experiments for producing circular cups and square cups were carried out for various working conditions, such as forming temperature and blank shapes. The limit drawing ratio(LDR) of 2.63 in warm deep drawing of circular cups in case of A5020-H32 sheet, whereas LDR of 2.25 in case of A1050-H16, could be obtained and the former was 1.4 times higher than the value at room temperature. The maximum relative drawing depth for square cups of A5020-H32 material was also about 1.92 times deeper than the depth drawn at room temperature. The effects of blank shape and forming temperature on drawability as well as thickness distribution of drawn cups were examined and discussed.

• Carbon letters
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• v.15 no.1
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• pp.50-56
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• 2014

We prepared ethylene vinyl alcohol (EVOH)/graphene oxide (GO) membranes by solution casting method. X-ray diffraction analysis showed that GOs were fully exfoliated in the EVOH/GO membrane. The glass transition temperatures of EVOH were increased by adding GOs into EVOH. The melting temperatures of EVOH/GO composites were decreased by adding GOs into EVOH, indicating that GOs may inhibit the crystallization of EVOH during non-isothermal crystallization. However, the equilibrium melting temperatures of EVOH were not changed by adding GOs into EVOH. The oxygen permeability of the EVOH/GO (0.3 wt%) film was reduced to 63% of that of pure EVOH film, with 84% light transmittance at 550 nm. The EVOH/GO membranes exhibited 100 times better (water vapor)/(oxygen) selectivity performance than pure EVOH membrane.

• Journal of the Korean Ceramic Society
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• v.32 no.12
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• pp.1331-1336
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• 1995

The glass-ceramics for ferro-electric were made from compositions of 70PbO.16TiO2.8SiO2.4B2O3.2AlPO4 (wt%) and 67.5PbO.20TiO2.8.5SiO2.2B2O3.2AlPO4 (wt%). The crystallization kinetics for PbTiO3 crystalline phase formation from glass was studied using non-isothermal DSC techniques. The values of activation energy, ΔE using variables of heating rate and temperature were calculated at various reaction fractions obtained from peak area over DSC. The results indicated that activation energy was lowest at 60% reaction fractions and the activation energy of glass containing 20.0 wt% TiO2 is higher than that of glass containing 16.0 wt% TiO2. The crystallization mechanism was three dimensional growth (n=4).

• Elastomers and Composites
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• v.51 no.2
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• pp.122-127
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• 2016

Thermal decomposition kinetics for two different types of polyurethane elastomers prepared with 2,2'-dichloro-4,4'-methylenedianiline (MOCA) and 3,5-dimethyl-thiotoluenediamine (Ethacure-300), based on PTMG/TDI isocyanate prepolymer, were studied using non-isothermal thermogravimetric analysis (TGA). Thermograms were obtained and analyzed using Friedman (FR) and Kissinger-Akahira-Sunose (KAS) methods for activation energy, $E_a$. The results obtained showed that decomposition reaction of both samples was observed similarly to occur through three different stages, i.e., initial stage with vaporization of low molecular weight materials, second stage of urethane linkage decompositions, and later stage of polyol segment decompositions. However, activation energy values at each stage for the sample cured with Ethacure-300 was much lower than those for the sample with MOCA, exhibiting relatively lower thermal stability for the sample with Ethacure-300 than that with MOCA.