• Journal of Korean Society of Forest Science
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• v.113 no.1
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• pp.107-117
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• 2024

This study investigated temporal changes in forest physical variables and their effects on thermal comfort and physiological and psychological responses. Environmental factors (air temperature, mean radiant temperature, wind speed, and relative humidity), the predicted mean vote (PMV), and the predicted percentage of dissatisfied (PPD) visitors were continuously measured between 9:00 AM and 6:00 PM. We assessed the physiological and psychological responses (heart rate variability, heart rate, oral temperature, blood pressure, pulse rate, thermal sensation vote, comfort sensation vote, and subjective feelings) of 30 male university students (average age: 21.7±1.9 years), who closed their eyes and relaxed for 5 minutes every hour. Examination of correlations between environmental factors and physiological responses showed that ① the mean radiant temperature, wind speed, and relative humidity significantly changed with time; ② PMV and PPD also showed significant changes over time, and the thermal sensation vote corresponded with PMV; however, the comfort sensation vote did not correspond with PPD; ③ Among the physiological responses, parasympathetic nerve activity, sympathetic nerve activity, heart rate, and diastolic blood pressure significantly varied with time, with parasympathetic nerve activity having the lowest value and sympathetic nerve activity the highest at the highest air temperature (2:00-4:00 PM); and ④ Air temperature, mean radiant temperature, and wind speed showed a negative correlation with parasympathetic nerve activity and a positive correlation with sympathetic nerve activity. These findings indicate that the relaxation effects of the forest environment depend on what time of day people are exposed to it, and the changes occurring in forest environmental factors over time modulate these effects.

• Fibers and Polymers
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• v.2 no.3
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• pp.129-134
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• 2001

Liquid crystalline (LC) poly(ethylene terephthalate-co-2(3)-chloro-1,4-phenylene terephthalate) (50/50, mole/mole) [PECPT] was synthesized and blended with polycarbonate (PC). LC properties of PECPT and thermal, morphological, and rheological behaviors of the PECPT/PC blend were studied. PECPT showed the nematic LC phase and much longer relaxation time than poly(ethylene terephthalate) (PET). The apparent melt viscosity of PECPT was one third of that of FET. An abrupt torque change was observed during the blending process due to the orientation of LC domains. For the blends containing 10~30 wt% of PECPT, the complex viscosities were higher than that of PC. As PECPT content increases above 40 wt%, shear thinning was observed. The lowest complex viscosity was obtained at 40~50 wt%. Transesterification of PECPT and PC was confirmed by the selective chemical degradation of carbonate groups in PC.

• Geomechanics and Engineering
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• v.23 no.3
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• pp.217-225
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• 2020

In this paper, the thermoelastic interactions in a two-dimension porous body are studied. This problem is solved by using the Green and Lindsay (GL) generalized thermoelasticity model under fractional time derivative. The derived approaches are estimated. with numeral results which are applied to the porous mediums in simplifying geometrical. The bounding plane surface of the present half-space continuum is subjected to a pulse heat flux. We use the Laplace-Fourier transforms methods with the eigenvalues approach to solve the problem. The numerical solutions for the field functions are obtained numerically using the numerical Laplace inversion technique. The effects of the fractional parameter and the thermal relaxation times on the temperature field, the displacement field, the change in volume fraction field of voids distribution and the stress fields have been calculated and displayed graphically and the obtained results are discussed.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.4
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• pp.326-332
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• 2008

In this work CdS films were prepared by using chemical bath deposition, which is simple and inexpensive technique suitable for large deposition area. Annealing in air at different temperatures (300, 350, 400, 450 and $500^{\circ}C$) at constant time of 30 min, also for different times (15, 30, 45, 60 and 90 min) at constant temperature ($300^{\circ}C$) is achieved. X-Ray analysis has confirmed the formation of cadmium oxide (CdO) with slight increase in grain size, shift towards lower scattering angle due to relaxation in the tensile strain for deposition films, and structure change from cubic and hexagonal to the hexagonal. From electrical properties, significant increase in electrical conductivity appeared in samples annealed at $300^{\circ}C$ for 60 min, and at $350^{\circ}C$ for 30 min.

• Journal of Mechanical Science and Technology
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• v.18 no.1
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• pp.12-19
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• 2004

Using LSM (laser scanning method) , the radius of curvature due to thermal deformation in polyimide film coated on Si substrate is measured. Since the polyimide film shows viscoelastic behavior, i.e., the modulus and deformation of the film vary with time and temperature, we estimate the relaxation modulus and the residual stresses of the polyimide film by measuring the radius of curvature and subsequently by performing viscoelastic analysis. The residual stresses relax by an amount of 10％ at 100$^{\circ}C$ and 20% at 150$^{\circ}C$ for two hours.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.3
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• pp.119-123
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• 2015

The thermodynamic properties and structural geometry of $KMgCl_3{\cdot}6H_2O$ were investigated using thermogravimetric analysis, differential scanning calorimetry, and nuclear magnetic resonance. The initial mass loss occurs around 351 K ($=T_d$), which is interpreted as the onset of partial thermal decomposition. Phase transition temperatures were found at 435 K ($=T_{C1}$) and 481 K ($=T_{C2}$). The temperature dependences of the spin-lattice relaxation time $T_1$ for the $^1H$ nucleus changes abruptly near $T_{C1}$. These changes are associated with changes in the geometry of the arrangement of octahedral water molecules.

• Economic and Environmental Geology
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• v.27 no.4
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• pp.397-409
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• 1994

The seemingly scattered plot of heat flow versus crustal thickness is explained by geodynamic processes and simple thermal relaxation in two contrasting tectonic elements. Elevated heat flow is characteristic of rift provinces where the crust is attenuated by stretching but also of orogenic belts where thrust tectonics thickens the crust and significantly enhances crustal heat production. With the progression of time, isostatic processes thin the thickened crust through uplift and erosion and thicken the rifted crust through subsidence and sedimentation. Heat flow relaxes to a value in equilibrium with background mantle heat flow.

• Earthquakes and Structures
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• v.9 no.3
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• pp.577-601
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• 2015

The thermomagnetic effect on plane wave propagation at the liquid-solid interface with nonclassical thermoelasticity is investigated. It is assumed that liquid-solid half-space is under initial stress. Numerical computations are performed for the developed amplitude ratios of P, SV and thermal waves under Cattaneo-Lord-Shulman theory, Green-Lindsay theory and classical thermoelasticity. The system of developed equations is solved by the application of the MATLAB software at different angles of incidence for Green and Lindsay model. The effect of initial stress and magnetic field in the lower half-space are discussed and comparison is made in LS, GL and CT models of thermoelasticity. In the absence of magnetic field, the obtained results are in agreement with the same results obtained by the relevant authors. This study would be useful for magneto-thermoelastic acoustic device field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1494-1501
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• 2006

Mechanical and physical properties of a copper alloy for a liquid rocket engine(LRE) combustion chamber liner application were tested at various temperatures. All test specimens were heat treated with the condition they might experience during actual fabrication process of the LRE combustion chamber. Physical properties measured include thermal conductivity, specific heat and thermal expansion data. Uniaxial tension tests were preformed to get mechanical properties at several temperatures ranging from room temperature to 600$^{\circ}C$. The result demonstrated that yield stress and ultimate tensile stress of the copper alloy decreases considerably and strain hardening increases as the result of the heat treatment. Since the LRE combustion chamber operates at higher temperature over 400$^{\circ}C$, the copper alloy can exhibit time-dependent behavior. Strain rate, creep and stress relaxation tests were performed to check the time-dependent behavior of the copper alloy. Strain rate tests revealed that strain rate effect is negligible up to 400$^{\circ}C$ while stress-strain curve is changed at 500$^{\circ}C$ as the strain rate is changed. Creep tests were conducted at 250$^{\circ}C$ and 500$^{\circ}C$ and the secondary creep rate was found to be very small at both temperatures implying that creep effect is negligible for the combustion chamber liner because its operating time is quite short.

• Journal of Biomedical Engineering Research
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• v.37 no.4
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• pp.134-139
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• 2016

US Food and Drug Administration (FDA) approved as a innovative cure for cancer, 1996. The effect is death of cancer cells through necrosis, apoptosis. Mainly the Continuous Wave mode (CW) use for PDT Laser. It sting, the question including itch, and etc. Reportedly, the increase of temperature with the perforated edema, ulcer, necrosis. The Thermal relaxation time and Oxygen recovery time is necessary. To give a normal oxygen recovery time of the cell, used Pulse mode. Progress, it was Burst Pulse mode when easing the thermal wake, the simplicity was secured, the PDT effect is good. Excepted in control group CW, Pulse, Burst pulse mode were incubated with various concentrations of 5-aminolevulinic acid hydrochloride (ALA-5). The tumor size reduction CW mode (44%), Pulse mode (48%), Burst pulse mode (53%) at 4 week after PDT with 0.3, 0.3, 0.3 mg/ml of ALA-5. After 4 hours, investigation of 100, 100, $100J/cm^2$ laser irradiation. The pulse mode was superior in expirimental data analysis. And it was the Burst pulse mode edge head of a family effect.