• Journal of the Korean Ceramic Society
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• v.30 no.3
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• pp.229-235
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• 1993

Thermal history and thermal stress of alumina specimen, which occured from thermal shock process, were calculated by finite difference method. Stress intensity factor and crack growth in cyclic thermal fatigue were calculated from single thermal shock temperature history and thermal stress. Cyclic thermal life were estimated by bending strength after cyclic thermal shock under critical thermal shock temperature. Calculated stress intensity factor was compared with real experimental thermal fatigue life of specimen. Fatigue life until critical stress intensity factor and real experimental result were comparable.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.226-231
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• 2001

The purpose of this paper is to propose the experimental method of thermal properties of Phase Change Materials (PCMs) by using T-history method. As far, in order to measure the heat of fusion and specific heat of PCMs, conventional thermal analysis methods such as DSC and DTA have been used. Because these methods test very small samples, thermal properties of samples are usually different from those of materials consisting of several components. For these reasons, T-history method, the simple measurement method of the heat of fusion and specific heat of PCMs have been performed. In this paper, we investigated the thermal properties of low temperature PCMs(below $0^{\circ}C$) under the charging process by using T-history method. The results are compared to those of DSC method. The T-history method will be useful for selection of the best PCM from lots of candidates and development of new PCMs.

• Journal of the Korean Ceramic Society
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• v.32 no.2
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• pp.183-188
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• 1995

The properties of the glasses are not dominantly dependent on the chemical composition, temperature, and pressure but also on the thermal history. For example, electrical, thermal, optical, and mechanical properties are all known to be strongly dependent on the thermal history. Fluoride glasses have received a great deal of attention as candidate materials for an infra-red transmitting medium. A series of fluoride glasses and fibers were prepared under a nitrogen atmosphere. Thermal history effects of the fluoride glass fibers associated with the fast cooling rate employed during the fiber drawing process were discussed in terms of the glass temperatures and the fictive temperatures on the basis of the results obtained from the Differential Scanning Calorimeter (DSC) measurements of the fiber and bulk forms of the same chemical composition.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.12
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• pp.1223-1229
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• 2001

Though conventional calorimetry methods such as differential scanning calorimetry (DSC) and differential thermal analysis (DTA) are used generally in measuring heat of fusion, T-history method has the advantages of a simple experimental apparatus and no requirements of sampling process, which is particularly useful for measuring thermal properties of inhomogeneous phase change materials (PCMs) in sealed tubes. However, random criteria (a degree of supercooling) used in selecting the range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion. In the present study, it was shown that a 40% discrepancy exists between the original T-history and the present methods when analyzing the same experimental data. As a result, a reasonable modification to the original T-history method is proposed.

• Polymer(Korea)
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• v.24 no.5
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• pp.656-663
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• 2000

The Effects of thermal history during the melt spinning process on the mechanical properties and crystallinity of polylactic acid (PLLA) fibers have been studied. Thermal history applied on PLLA during the melt process caused the decrease of number-average molecular weights and this resulted in the lowering of orientation and crystallinity in PLLA fibers. As a result, the longer applied thermal history, the less tensile strength and modulus, and the higher elongation at break. It was also found that primary factor for controlling crystallinity of PLLA fiber was the stress induced crystallization while the thermal induced crystallization had a little effect on the crystallinity of PLLA fibers. However, the thermal induced crystallization turn out to be important in the crystallinity developed by annealing of PLLA fibers.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2506-2511
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• 2007

The coupled simulation is performed to find out the interaction of arc plasmas with surrounding materials in a thermal puffer plasma chamber. In order to be more realistic, PTFE nozzle ablation and Cu electrode evaporation, which are caused by high temperature of arc plasmas, are considered together. Pressure rise and temperature inside the chamber generated during the whole arcing history are investigated with the applied currents. It is very important to define how thermal flow and mass transfer are processing between the arc plasma and surrounding materials for further understanding complex physics inside the chamber. It is concluded that the result might be very useful to understand the mechanism happened inside and to design thermal puffer plasma chambers, but further experimental studies are required to verify the results for the more practical applications.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1575-1577
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• 1999

XLPE is widely used as a main insulation in EHV power cables, deeply connected with thermal stress. In this study, the thermal history of XLPE insulation was examined using DSC(Differential Scanning Calorimetry). The principle is on the basis of the phenomenon that crystal in polyethylene is rearranged as it is annealed near/below the melting temperature. From the result, it was possible to define accurate temperature which was really applied on the XLPE insulation and this method was assured as a useful tool in characterization of thermal history in XLPE cable insulation.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.83-91
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• 1996

A recycling soap was prepared from non-cooking oils. The effects of physlcal and chemical properties of the recycling soap on biodegradation are expected to be different due to the thermal histories of the non-cooking oils. Therefore, the biodegradation rate of the recycling soap was studied by using Klebssella Pneumoniae(K. pneumoniae), and the growth rate of K. pnewoniae in soap solution was observed. The biodegradation rate of the recycling soap appeared to be slower as the thermal histories of the non-cooking oils became larger. This might be resulted from hydrolysis, in which the ester bonds in the oils are broken to produce hydroxyl group. It was also observed that the growth rate of the microorganism decreased with the increase in the thermal histories of the oils. As a result, it is desired that recycling soap should be produced from the non-cooking oils with the prober ranges of thermal histories to reduce water contamination. The non-cooking oils with larger thermal histories are considered to be recycling through the cracking process before used. Key Words : non-cooking oils, recycling soap, thermal history, biodegradation, microorganism growth.

• Journal of Acupuncture Research
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• v.27 no.5
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• pp.89-96
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• 2010

Objectives : This study is designed to evaluate the diagnostic significances of DITI on the patients of low back pain according to impression, symptoms and medical history. Methods : According to impression, symptoms and medical history, thermal changes of $BL_{23}$, $BL_{26}$, $BL_{40}$, $BL_{57}$, $GB_{31}$ and $BL_{60}$ were compared forty-eight low back pain patients and twenty-three normal group. Results : Surface temperature of $BL_{26}$ in case of L-spine HNP is significantly higher than normal group. Surface temperature of $BL_{26}$ in case of low back pain is significantly higher, $GB_{31}$ of radiating pain is significantly lower than normal group. Surface temperature of $BL_{26}$ in case of acute stage is significantly higher, $GB_{31}$ of chronic stage is significantly lower than normal group. Conclusions : Thermal changes of $BL_{26}$ and $GB_{31}$ on the patients of low back pain compared with normal group, according to impression, symptoms and medical history has significances.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.1
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• pp.32-39
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• 2003

Though conventional calorimetry methods such as differential scanning calorimetry and differential thermal analysis are used generally in measuring heat of fusion, T-history method has advantages of a simple experimental apparatus and no requirements of sampling process, which is particularly useful for measuring thermophyical properties of in-homogeneous phase change materials in sealed tubes. However, the degree of supercooling used in selecting a range of latent heat release and neglecting sensible heat during the phase change process can cause significant errors in determining the heat of fusion. In the present study, it was shown that a 40% discrepancy exists between the original T-history and the present methods when analyzing the same experimental data. As a result, a reasonable modification to the original T-history method is proposed.