• Journal of the Korean Ceramic Society
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• v.24 no.6
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• pp.586-592
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• 1987

The role of the strain energy and phase stability in the diffuse phase transition have been investigated in the highly disordered solid solution, (Pb1-xBax)(Zr0.4Ti0.6)O3 (0.2 x 0.4). X-ray diffraction analysis indicates that tetragonality (c/a) decreases with the increasing Ba content. Also as the Ba content increases, phase transition becomes more diffuse and at the same time dielectric relaxation as a function of measured frequencies in the 1KHz-10MHz range occurs very pronouncedly. In the Ba content range, 0.2 x 0.35, hysteresis loops are routinely observed and the loop is observed to narrow shape as the Ba content increases but becomes very slim at 40mol% Ba content. Moreover thermal analysis shows that there is no abrupt change in the thermal expansion coefficient below the apparent transition temperature at which dielectric constant becomes maximum. From the above results, it has been concluded that creation of the strain energy due to the distorthion that occurred during the phase transition suppresses diffuse phase transition.

• Journal of Power Electronics
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• v.10 no.3
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• pp.219-227
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• 2010

Telecom supplies need to conform to low Total Harmonic Distortion (THD) and high Power Factor (PF) as per IEC 61000-3-2 and IEEE 519-1992 standards. These high rating power supplies use a three phase utility in which low THD and high PF are realized via various passive and active wave shaping schemes. In this paper, a new design for three phase telecom power supplies is presented with circuit parameter values optimized for high performance in terms of a low THD, high PF, low ripple and high line and load regulation using a suitable combination of various strategies. The performance of the power supply is validated by extensive simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12B
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• pp.1733-1740
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• 2001

A monolithic 5 GHz image reject mixer using a 0.5-m GaAs MESFET technology is designed and simulated. The Mixer exhibits a 13.56 dB down-conversion gain, a SSB (Single SideBand) noise figure of 11.91 dB, an input IP3 (third order intercept point) of -3.73 dBm and a PldB (1-dB compression point) of -11.0 dBm. The critical issue in the image reject mixer is the phase accuracy and magnitude balance of the 90 phase shifting network. The proposed image reject mixer realizes a 90 phase shifter on chip. This phase shifting network does not need any phase adjusting to achieve the phase error specification of 3 over a frequency range from 800 MHz to 1GHz. The simulated overall image rejection ratio is better than 50 dB.

• The KSFM Journal of Fluid Machinery
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• v.11 no.3
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• pp.7-13
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• 2008

The cavitating flow simulation is of practical importance for many engineering systems, such as pump, turbine, nozzle, Infector, etc. In the present work, a solver for two-phase flows has been developed and applied to simulate the cavitating flows past hydrofoils. The governing equation is the two-phase Navier-Stokes equation, comprised of the continuity equation of liquid and vapor phase. The momentum and energy equation is in the mixture phase. The solver employs an implicit, dual time, preconditioned algorithm using finite difference scheme in curvilinear coordinates. An experimental data and other numerical data were compared with the present results to validate the present solver. It is concluded that the present numerical code has successfully accounted for two-phase Navier-Stokes model of cavitation flow.

• Journal of Powder Materials
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• v.3 no.3
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• pp.174-180
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• 1996

Microstructure and phase transformation of mechanically alloyed TiNi powders added to aluminium matrix for enhancing the damping properties were studied. Four compositions between 48.5 and 51.5 at% Ti intermetallic compounds were selected to control the fraction of martensite phase. Mechanically alloyed TiNi powders were heat-treated at vacuum of $10^{-6}$ torr for crystallization. Ball milled AI/TiNi composite powders were swaged at room temperature and rolled at 450 $^{\circ}C$. After mechanical alloying for 10 hours, Ti and Ni elements were alloyed completely and amorphous phase was formed. Amorphous phase was crystallized to martensite (Bl9') and austenite(B2) after heat treating for 1 hour at the temperature of 850 $^{\circ}C$, and TiNi$_3$, intermetallic compound was partially formed. Considerable amount of martensite phase was remained after swaging and rolling.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.392-397
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• 2005

This study is investigated the supercooling improvement and the phase change temperature of the TMA clathrate compound including TMA(Tri-Methyl-Amine, ($(CH_3)_3N$) of 25 wt% with additive as a low temperature storage material at $6^{\circ}C$ and $-7^{\circ}C$ of heat source. The additive is ethanol of 0.1, 0.3 wt% and 0.5 wt%. The results showed that as the concentration of ethanol is increased, the phase change temperature, the degree of supercooling and the retention time of liquid phase are decreased. Especially, TMA 25 wt% clathrate compound with ethanol of 0.5wt% has the average of phase change temperature of $3.8^{\circ}C$, degree of supercooling of $0.9^{\circ}C$, $0.8^{\circ}C$ and retention time of liquid phase for 6, 5 minutes at $-6^{\circ}C$, $-7^{\circ}C$ of heat source. From the results of this study, TMA 25wt% clathrate compound with ethanol 0.5wt% showed supercooling repression effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.266-273
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• 2020

This study was undertaken to determine the effects of diet supplementation with complex probiotics (CPB), on growth performance, nutrient digestibility, blood metabolites, noxious gas, and fecal microflora in weaning pigs. On the basis of body weight, a total of 234 weaned pigs (Landrace×Yorkshire×Duroc, 6.14±0.78kg) were randomly allotted to 3 treatments and 6 replicates (13 pigs per pen). The experimental diets were fed in a meal form for 28 days (days 0-14, PhaseI, and days 15-28, PhaseII). The dietary treatment groups were as follows: T1 (basal diet), T2 (T1+0.13% CPB) and T3 (T1+0.25% CPB). The CPB supplement contained Bacillus subtilis 1.0×10⁶ CFU/g, Enterococcus faecium 1.0×10⁶ CFU/g, Saccharomyces cerevisiae 1.0×10⁶ CFU/g, Bacillus licheniformis 3.0×10⁸ CFU/g, and Bacillus polyfermenticus 3.0×10⁸ CFU/g. Pigs fed the T3 diet showed an increase (p<0.05) in the overall average daily gain and average daily feed intake, increased (p<0.05) crude protein digestibility in PhaseI, and greater (p<0.05) dry matter and gross energy digestibility in PhaseII. Supplementation of CPB had no effect on the blood profile. Furthermore, pigs fed the T3 diet had lower (p<0.05) NH₃ emission and overall count of fecal Clostridium spp. In conclusion, we believe that CPB supplementation has a beneficial effect on growth performance, nutrient digestibility, noxious gas, and fecal microflora in weaning pigs.

• Journal of the Korean Ceramic Society
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• v.35 no.11
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• pp.1130-1140
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• 1998

Thin films of $Bi_4Ti_3O_{12}\;nBaTiO_3(n=1&2)$ were prepared using sols erived Ba-Bi-Ti complex alkoxides. The sols were spin-cast onto $Pt/Ti/SiO_2/Si$ substrates and followed by pyrolysis for 1 hr at $620^{\circ}C,\;700^{\circ}C\;and\;750^{\circ}C$ In the thin films a pyrochlore phase seemed to be formed at a lower temperature and then tran-formed to the layered perovskite phase as the heating temperature increased. In the thin films pyrolyzed at formed to the layered perovskte phase as the heating temperature increased. In the films pyrolyzed at $750^{\circ}C$ the amount of $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ reached to 94% while $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ was 77% in composition. This result shows that the formation of the layered pervoskite phase becomes difficult as the amount of complexing $BaTiO_3$ increases. The microstructures and the electrical properties of the thin films were gen-erally improved with the incease of the heating temperature. However the presence of the pyrochlore phase could not be removed effectively. Our study showed that the electrical properties of $Bi_4Ti_3O_{12}{\cdot}BaTiO_3$ were pronouncedly improved with complexing with BaTiO3 when compared to those of $Bi_4Ti_3O_{12}$ while the presence of the pyrochlore phase was detrimental to the those of $Bi_4Ti_3O_{12}{\cdot}2BaTiO_3$.

• Korean Journal of Materials Research
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• v.3 no.4
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• pp.410-421
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• 1993

Phase equilibria and reaction paths of the superconducting phases and other compatible phases at $850^{\circ}C$ in the Bi-Sr-Ca-Cu-O system were studied. $Bi_2O_3$ was added to $Sr_2CaCu_2O_x$ by 5% up to 40 mole% Bi in the pseudo-binary $Bi_2O_3-(Sr_2CaCu_2O_x)$ system and the heat treated samples were analysed using XRD. SEM, EDS. and DT A. When Bi contents were greater than 35 mole% Bi, liquid phase was formed which was compatible with $Bi_2Sr_2CaCu_2O_8$ phase. The m.p. of $Bi_2Sr_2CaCu_2O_8$ phase decreased as the content of (Sr+Ca)decreased. $Bi_{2+x}Sr_2CaCu_2O_8$ phase first segregated out of liquid phase around $Bi_2Sr_2CaCu_2O_8$ phase during cooling of liquid phase.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.313-320
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• 2023

A total of 96 weanling pigs with an initial body weight of 5.96 ± 0.08 kg were randomly allocated to two dietary treatments and fed experimental weaning diets for 36 days in three phases; phase 1: day 1 to 7; phase 2: day 8 to 21, and phase 3: day 22 to 36. Treatments consisted of a basal diet (CON) containing 334.0 g/kg dried whey versus a lactic acid (LA) supplemented diet containing 313.6 g/kg dried whey with 10 g/kg LA during phase 1; a CON diet containing 200.0 g/kg dried whey versus an LA diet containing 186.0 g/kg dried whey with 7 g/kg LA during phase 2. During phase 3, both CON and LA groups were fed a diet without dried whey and LA. Pigs fed the LA diet had a higher average daily feed intake ADFI (p = 0.014) and reduced (p = 0.035) gain-feed ratio compared to pigs fed CON diet in phase 2. In phase 3, the average daily gain and feed intake were both increased (p = 0.026 and; p = 0.010, respectively) in the pigs previously fed the LA diet than those fed the CON diet. The apparent total tract digestibility of dry matter and, nitrogen, and the digestible energy were decreased (p < 0.05) in the LA diet group on day 7; however, increased (p < 0.05) digestibility of dry matter and nitrogen and digestible energy was observed at the end of phase 2 and 3. In conclusion, the inclusion of LA was inferred to have improved the average daily gain, feed intake, and nutrient digestibility during the late weanling period of pigs.