• Journal of Biosystems Engineering
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• v.21 no.1
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• pp.84-93
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• 1996

Several paraffins(CnH2n +2) can be used as the thermal energy storage medium because of their large amount of latent heat and their flexibility of phase change temperature. But they have not been used in the thermal energy storage system because their long term stability have not been verified. Paraffins(CnH2n+2) which the values of n are 23, 24, 26 and 28 were selected for this experimental research. And this research was peformed to apply them to the practical systems. The results were summarized as follows. (1) The increase of phase change cycles had no effect on their phase change temperatures. (2) According as the values of n increased from 23 to 28, the specific heats of paraffins(CnH2n+2) increased, and were in the range of 0.47 0.75 ㎉/$kg^circ C$. (3) Thermal conductivities of them were in the range of 0.14 0.17 W/$m^circ C$. and specific gravities of them were in the range of 765800 kg/m3. (4) The density of paraffins was in the range of 765 800 kg/$m^circ C$ , and the density of solid phase was larger than that of liquid phase. (5) When the number of phase change cycles was 1, 500 cycles, the latent heat of paraffins was 90% of the initial value.

• International Journal of Air-Conditioning and Refrigeration
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• v.16 no.1
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• pp.22-29
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• 2008

A sequence of visually experimental observations was conducted to investigate the flow boiling and two-phase flow in a coiled tube. Different boiling modes and bubble dynamical evolutions were identified for better recognizing the phenomena and understanding the two-phase flow evolution and heat transfer mechanisms. The dissolved gases and remained vapor would serve as foreign nucleation sites, and together with the effect of buoyancy, centrifugal force and liquid flow, these also induce very different flow boiling nucleation, boiling modes, bubble dynamical behavior, and further the boiling heat transfer performance. Bubbly flow, plug flow, slug flow, stratified/wavy flow and annular flow were observed during the boiling process in the coiled tube. Particularly the effects of flow reconstructing and thermal non-equilibrium release in the bends were noted and discussed with the physical understanding. Coupled with the effects of the buoyancy, centrifugal force and inertia or momentum ratio of the two fluids, the flow reconstructing and thermal non-equilibrium release effects have critical importance for flow pattern in the bends and flow evolution in next straight sections.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3223-3226
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• 2013

Spherical phospholipid-bilayers, vesicles, were prepared using the layer-by-layer double emulsion technique, which allows the bilayer to be formed asymmetrically. On the outer layer of the vesicles, the phospholipase D (PLD) reacted to convert phosphatidylcholine (PC) to phosphatidic acid (PA). The reaction induced the curvature change of the vesicles, which eventually led to rupture. The response time from the time of PLD injection to the time of rupture was measured against different vesicle curvatures and the outer layer phase, using the fluorescence intensity change of a pH-sensitive dye encapsulated within the vesicles. The effect of the vesicle curvature on the response was observed to be more significantly dramatic at the solid phase, compared to the liquid phase. Furthermore, in the solid phase, the response time was faster for 80 and 155 nm vesicles and, slower for 605 nm vesicles than similarly sized vesicles in the liquid phase vesicles. This difference in the response time was thought to result from the configuration determined by the phase difference and the PLD behavior.

• Korean Journal of Psychosomatic Medicine
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• v.3 no.2
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• pp.115-125
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• 1995

Reports about the prevalence of premenstrual symptoms state that occurs in 20 to 100% of most reproductive-age women. There is a close association between premenstrual syndrome and affective disorders as well as same some other psychiatric disorders. Late luteal phase dysphoric disorder (LLPDD) is a premenstrual condition defined in DSM-III-R by severe mood changes and other symptoms that repeatedly occur only in the luteal phase of the menstrual cycle. However, DSM-III-R does not specify how to compute the change from the follicular to the luteal phase or how to determine when the amount of change is great enough to warrant the diagnosis nor how to determine occupational or social functional impairment. This study was conducted to evaluate the nature, severity and magnitude of premenstrual syndrome in women with current psychiatric disorders by using prospective Daily Rating Form(DRF), and to measure symptom changes according to three scoring methods for diagnosing LLPDD. Our study obtains the data about premenstrual changes estimated by DRF from 22 women with psychiatric disorders who had met criteria for major depressive syndrome on the Premenstrual Assessment Form (PAF). The data was scored by each three methods and was determined to meet criteria A for LLPDD. The results are as follows: 1) the subjects, when scored according to the percent change method, effect size method and absolute severity method, met the DSM-III-R criteria A for LLPDD in 36.4% (8 subjects), 14% (3 subjects) and 4.5% (1 subject) of the cases respectively. 2) The items of irritability, anger and impatience were occurred most frequently on the DRF, when it was scored according to the three scoring methods. And the item of breast pain was next frequent according to the effect size method and the percent change method but according to the absolute severity method. 3) The PAF item of impaired social functioning was reported by 16 (73%) of the subjects. 4) 4 (18%) of the subjects met criteria A for LLPDD and reported impaired social functioning. The prevalency of LLPDD according to each method varied. The percent change method yielded the greatest (36.4%), and the absolute seventy method yielded the laest (4.5%), The effect size method yielded an intermediate frequency (14%). Therefore, for maximizing the diagnostic accuracy of LLPDD, a diagnostic procedure including a measure of change (e.q., effect size method, percent change method) as well as confirmed diagnosis by DRF, will be needed. Also, an accurate tool to evaluate impaired social functioning will be required.

• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.33-38
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• 2011

Medicated water electrolysis apparatus, which electrolyzes water into acidic water and alkaline water, was in the spotlight as becoming known the effect of alkaline water. It is known as good for health as removing active oxygen in the human's body and promoting digestion. But, the customers could not get that desired water temperature because these apparatuses are directly connected with a water pipe. So, the cooling system was developed for controlling the temperature of the alkaline water. One of the typical way is to store water in water tank and control the temperature. But, in this way, storing water can be polluted impurities coming from outside. For protecting this pollution, the cooling system based on indirect heat exchange method through phase change between water and ice was developed. In this study, we have calculated efficiency of the cooling system with phase change by experiment and commercial CFD(Computational Fluid Dynamics) code, ANSYS CFX. To consider the effect of latent heat that is generated by melting ice, we have simulated two phase numerical analyses used enthalpy method and found the temperature, velocity, and ice mass distribution for calculating the efficiency of cooling. From the results of numerical analysis, we have obtained the relationship between the cooling efficiency and each design factor.

• Advances in materials Research
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• v.12 no.3
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• pp.211-226
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• 2023

The present work is considered to study the two-dimensional problem in an orthotropic magneto-thermoelastic media and examined the effect of thermal phase-lags and GN-theories on Rayleigh waves in the light of fractional order theory with combined effect of rotation and hall current. The boundary conditions are used to derive the secular equations of Rayleigh waves. The wave properties such as phase velocity, attenuation coefficient are computed numerically. The numerical simulated results are presented graphically to show the effect of phase-lags and GN-theories on the Rayleigh wave phase velocity, attenuation coefficient, stress components and temperature change. Some particular cases are also discussed in the present investigation.

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.219-226
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• 1996

The wave-particle duality of light plays important role in quantum optics and it often produces a result different from that of classical wave theory. In this paper, we study the intensity and phase fluctuation of light which show certain change after light goes through a beam splitter, and show the difference between the classical and quantum theory. We show quantitatively that the uncertainty of phase increases at the output of a beam splitter due to the contribution of vacuum fluctuation, even though classical theory predicts no such change in phase fluctuation. The expectation values of normally ordered operators are introduced where the vacuum effect is naturally eliminated, and it is shown that the classical informations are recovered in this way. Analysis on the expectation values produces a distinction between measured phase and inferred phase values and they are related through the contribution of vacuum field.

• Journal of the Korean Ceramic Society
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• v.30 no.10
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• pp.859-865
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• 1993

Morphotropic tetragonal and rhombohederal phase boundary(MPB) in PZT system was calculated and the effect of mechanical stress and electric field on the MPB was examined using phenomenological thermodynamic theory proposed by Devonshire. Mechanical stress and electric field was calculated to change free energies of phases and shift MPB. The stable composition range of the phase, of which spontaneous strain and spontaneous polarization aligned to the direction of tensile stress or electirc field, was expanded.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.11
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• pp.548-556
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• 2003

Switched reluctance motor(SRM) has simple magnetic structure, and needs simple power electronic driving circuit. It is very useful for wide range adjustable speed drive system. But, SRM drive generates large vibration and acoustic noise because it is commutated individually by step pulse m.m.f of each phase. In the vibration and acoustic noise characteristics. the considerable vibration and noise is induced by radial deforming of stator, so the frequency of dominant vibration and noise is coincident with the frequency of natural frequency of mechanical structure. This radial vibration force is generated by abrupt change of radial magnetic force in the phase commutation region. This paper studied about simple electromagnetic structure of SRM using auxiliary compensating winding for the reduction of noise and vibration. This auxiliary winding is coupled with all phase windings electromagnetically and absorb and transfer magnetic energy variation from phase to other phase. By this interaction of phase windings and compensating winding can reduce abrupt radial force change and vibration and acoustic noise. In this paper the improvement effect is examined by the test of prototype machine.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1201-1206
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• 2004

This paper deals with the numerical analysis of natural convection flow induced by the density inversion effect of water inside horizontal pipe. The numerical method is based on SIMPLE/PWIM in general coordinate for its wide applicabilities. The numerical tool was validated through the comparison with the previous results concerning the density inversion effect of water It is shown that the developed numerical tool could predict the flow pattern and the heat transfer phenomena qualitatively And it is also found that the density inversion effect of water has significant effects on the flow pattern.