• Fibers and Polymers
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• v.2 no.2
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• pp.75-80
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• 2001

The thermal degradation of poly(ethylene terephthalate-co-isophthalate)s (PETIs) is investigated by using isothermal thermogravimetric analysis at the temperature range of 280-31$0^{\circ}C$. The degradation rate of PETIs is increased as the mole ratio of ethylene isophthaloyl (EI) units in PETIs increases. The activation energies for the thermal degradation of poly(ethylene terephthalate), PETI(5/5), and poly(ethylene isophthalate) are 33.4, 16.6, and 8.9 kcal/mole, respectively. The degradation rate of PETIs is influenced by their volatile cyclic oligomer components formed during the polymerization and the thermal degradation. It is simulated by the rotational isomeric state model that the content of cyclic dimer in PETIs, which is the most volatile cyclic oligomer component, increases with the EI units in PETIs.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.243-248
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• 2015

We prepared semi-insulating CdTe for radiation detectors by isothermal annealing of single crystals grown by Bridgeman technique in a sealed quartz container filled with Sn vapor. The resistivity of CdTe:Sn samples thus obtained was of order of $10^{10}Ohm{\cdot}cm$ at room temperature with electrons lifetime of $2{\times}10^{-8}$ s, which is appropriate for the applications desired. Analysis of electric transport characteristics depending on temperature, sample thickness and voltage applied revealed the presence of traps with concentration of about $(4-5){\times}10^{12}cm^{-3}$ with the corresponding energy level at 0.8 - 0.9 eV counted from the bottom of conduction band. The conductivity was determined by electron injection from electrodes in space charge limited current mode.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.108.1-108.1
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• 2011

Turbulence is ubiquitous in astrophysical fluids such as the interstellar medium(ISM) and the intracluster medium(ICM). There are many driving mechanisms which can inject energy into the fluid in variety driving scales, But the plausible driving scale of ISM/ICM turbulence are yet unknown. Therefore, understanding different statistical properties between turbulence with single driving scale and turbulence with double driving scale is required. In this work, we performed 3-dimensional isothermal compressible, magnetohydrodynamic(MHD) turbulence simulations. We drive turbulence in the Fourier space in two ranges, 2

• Polymer(Korea)
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• v.26 no.6
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• pp.728-736
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• 2002

The thermal and dielectric properties of unsaturated polyester resin system during cure were analyzed under Isothermal conditions. Both $varepsilon$′ and $varepsilon$" decreased and dipole relaxation was observed under isothermal conditions during cure. The ionic conductivity decreased linearly with the conversion according to the Kienle-Rate equation (ln($varepsilon$"$_{ionic}$we$_{0}$)=C$_{r}$$alpha$+C$_{0}$) up to $alpha$=0.15, after which it aparted from the relationship due to the entanglement of polymer chains. The effect of ionic conductivity was revealed to be larger than that of dipole motion during the whole cure through the electrical modulus analysis. Although dielectric motion was analyzed with Debye model, it was observed only at a narrow time region of middle stage of cure. In order to estimate the dielectric properties during the whole cure, the Havriliak-Negami model was considered and modified with the strong effect of ionic conductivity. The changes of $varepsilon$′ and $varepsilon$" were well estimated with this modified Havriliak-Negami model.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.1011-1020
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• 1991

본 연구에서는 하향유동영역에서 수직면으로부터 경사각이 60˚ 이하인 경사 등온면이 저온의 물속에 잠겨 있을때 일어나는 다중정상상태 영역을 밝혀내고, 이 영 역에서 경사각이 열전달, 온도분포, 속도분포, 부력분포 및 누셀트 수에 미치는 영향 을 구명하였다. 또 해석방법은 이제까지 발표된 연구결과와 비교검토하기 위하여 기 존 논문에서와 같이 상이해석을 사용하였다.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.158-164
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• 2006

The creep behavior of newly developed composite geogrids which consists of PET yarns sheathed in PP were evaluated using SIM. For the SIM procedure, three test parameters, the applied loads, temperature steps and number of ribs were investigated, The study confirmed that temperature steps of 10 and 14$^{\circ}C$ up to 80$^{\circ}C$ are applicable for composite geogrids due to the different transition temperatures between two materials. At applied loads of 40 and 50%, only primary creep state was measured, while secondary creep state appeared at the applied loads of 60%, The lifetimes of composite geogrids were estimated at each of loading level using statistical reliability analysis technique. The results show that the lifetimes longer than 100 years can be predicted within 16 hours. Therefore, SIM is very effective and economical accelerated creep test methods, especially for lifetime prediction. This gives guidelines for users to select the appropriate factor of safety against creep considering the field condition within shorter test times.

• Metals and materials international
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• v.24 no.6
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• pp.1293-1302
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• 2018

Nanocrystalline (NC) Ni electrodeposits (EDs) with a mean grain size of $34{\pm}12nm$ has been investigated, from room temperature to $800^{\circ}C$ under a purge gas of argon, by both non-isothermal and isothermal differential scanning calorimetry measurements, in combination with characterization of temperature-dependent microstructural evolution. A significant exothermic peak resulting from superimposition of recrystallization and surface oxidation occurs between 340 and $745^{\circ}C$ at a heating rate of $10^{\circ}C/min$ for the NC Ni EDs. The temperatures for recrystallization and oxidation increase with increasing the heating rate. In addition, recrystallization leads to a profound brittle-ductile transition of the Ni EDs in a narrow range around the peak temperature for the recrystallization.

• Journal of applied mathematics & informatics
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• v.40 no.1_2
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• pp.99-115
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• 2022

The problem of Benard double diffusive Marangoni convection is investigated in a horizontally infinite composite layer system consisting of a two component fluid layer above a porous layer saturated with the same fluid, using Darcy-Brinkman model with constant heat sources/sink in both the layers. The lower boundary of the porous region is rigid and upper boundary of the fluid region is free with Marangoni effects. The system of ordinary differential equations obtained after normal mode analysis is solved in closed form for the eigenvalue, thermal Marangoni number for two types of thermal boundary combinations, Type (I) Adiabatic-Adiabatic and Type (II) Adiabatic -Isothermal. The corresponding two thermal Marangoni numbers are obtained and the essence of the different parameters on non-Darcy-Benard double diffusive Marangoni convection are investigated in detail.

• Journal of Life Science
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• v.26 no.5
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• pp.620-631
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• 2016

Viroids are about 250-400 base pair of short single strand RNA fragments have been associated with economically important plant diseases. Due to the lack of protein expression capacity associated with replication, it is very difficult to diagnosis viroid diseases in serological methods. For detecting viroid at plants, molecular-based techniques such as agarose gel electrophoresis, polyacrylamide gel electrophoresis (PAGE), DNA-hybridization, blotting analysis and conventional RT-PCR are reliable. Real-time RT-PCR methods that grafted on RT-PCR methods with improved confirmation methods have been also utilized. However, they are still labor-intensive, time-consuming, and require personnel with expertise. Loop-mediated Isothermal Amplification (LAMP) method is a nucleic acid amplification method under the isothermal condition. The LAMP methodology has been reported to be simple, rapid, sensitive and field applicable in detecting a variety of pathogens. The results of LAMP method can be colorized by adding a visible material such as SYBR green I, Evagreen, Calcein, Berberine and Hydroxy naphthol blue (HNB) with simple equipment or naked eyes. The combination of LAMP method and nucleic pathogens, viroids, can be used to realize simple diagnosis platform for the genetic point-of care testing system. The aim at this review is to summary viroid-caused diseases and the simple visible approach for diagnosing viroids using Loop-mediated Isothermal Amplification (LAMP) method.

• Polymer(Korea)
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• v.25 no.3
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• pp.359-366
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• 2001

Isothermal physical aging of a glass fiber/epoxy composite was examined at different aging temperatures ($T_a$) and degrees of conversion (monitored by the glass transition temperature, $T_g$) by means of the TBA torsion pendulum technique. The range of aging temperature was from 10 to $130^{\circ}C$ : the conversion was systematically changed from $T_g$=$76^{\circ}C$ to $T_g$=$177^{\circ}C$ (fully crosslinked). The effect of isothermal physical aging was manifested as perturbations of the modulus and mechanical loss vs. temperature in the vicinity of $T_a$ for all conversions. The rate of isothermal physical aging determined from the change of modulus with aging time at fixed aging temperature decreased and then increased with increasing conversion below T$_{a}$=9$0^{\circ}C$. There exists a superposition in aging rate vs. ($T_g$ -$T_a$) by shifting horizontally and vertically. This implies that the physical aging process is independent of the change of chemical structure as conversion proceeds. It has been found that water absorbed at the aging temperature below $70^{\circ}C$ during isothermal physical aging lowers the apparent aging rate. It is due to the absorbed water molecules forming strong polar interactions with hydroxyl group on network chain and reducing the segmental mobility during the physical aging.g.