• Journal of the Korean Ceramic Society
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• v.32 no.8
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• pp.915-921
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• 1995

The morphotropic phase boundary and phase transitions of the solid solutiion system, (1-x)(Na1/2Bi1/2)TiO3-PbTiO3＋xPbTiO3 were studied by investigating changes in crystal structure, variations in permittivity with temperature, and calorimetric behavior. It was observed that the morphotropic phase boundary (MPB) of this solid solutiion system was at near 14 mol% of PbTiO3. Compositions containing less than 10mol% PbTiO3 (x<0.1) exhibited a phase transition, i.e. ferroelectric rhombohedrallongrightarrowparaelectric paraelectric cubic, with increasing temperature. Composition containing more than 14 mol% PbTiO3 (x 0.14) showed a phase transition from ferroelectric tetragonal to paraelectric cubic. In the composition range of 0.1$\varepsilon$ (T) curve, which coincided with a phase transition from ferroelectric rhombohedral to an intermediate phase, was also found.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1546-1551
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• 2008

This paper is concerned with the problems of accurate losses segregation in capacitor-run single phase motor. Segregation of losses in single phase induction motor is more complicated than that in three phase induction motor, because of the backward magnetic field component in the motor. Generally there are two methods for losses segregation of single phase induction motor. The one is relatively complicated method based on parameter estimation of single phase induction motor. By the way, the other one is simplified method based on IEEE Standard 114. All of the methods for the experimental determination of single phase induction motor losses are studied in this paper. Since the IEEE Standard is not possible to be applied for all type of single phase induction motors, we modified that method to apply for losses segregation of capacitor-run single phase induction motor as unifying the method based on parameter estimation.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.33-39
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• 2022

A multi-phase brushless direct current (BLDC) motor is widely used in large-capacity electric propulsion systems such as submarines and electric ships. In particular, in the field of military submarines, the polyphaser motor must suppress torque ripple in various failure situations to reduce noise and ensure stable operation for a long time. In this paper, we propose a polyphaser current control method that can improve efficiency and reduce torque ripple by minimizing the increase in stator winding loss at maximum output torque by controlling the phase angle and amplitude of the steady-state current during open circuit failure of the stator winding. The proposed control method controls the magnitude and phase angle of the healthy phase current, excluding the faulty phase, to compensate for the torque ripple that occurs in the case of a phase open failure of the motor. The magnitude and phase angle of the controlled steady-state current are calculated for each phase so that copper loss increase is minimized. The proposed control method was verified using hardware-in-the-loop simulation (HILS) of a 12-phase BLDC motor. HILS verification confirmed that the increase in the loss of the stator winding and the magnitude of the torque ripple decreased compared with the open phase fault of the motor.

• Journal of the Korean Mathematical Society
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• v.58 no.2
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• pp.451-471
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• 2021

First, we define phase tropical hypersurfaces in terms of a degeneration data of smooth complex algebraic hypersurfaces in (ℂ∗)n. Next, we prove that complex hyperplanes are homeomorphic to their degeneration called phase tropical hyperplanes. More generally, using Mikhalkin's decomposition into pairs-of-pants of smooth algebraic hypersurfaces, we show that a phase tropical hypersurface with smooth tropicalization is naturally a topological manifold. Moreover, we prove that a phase tropical hypersurface is naturally homeomorphic to a symplectic manifold.

• Journal of Ocean Engineering and Technology
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• v.6 no.2
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• pp.85-93
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• 1992

The only hardness of 2nd phase of martensite in dual phase steel which was composed of the martensite and ferrite was changed. Fatigue test was conducted by cantilever type of self-made rotated bending fatigue testing machine. The corrosion fatigue fracture behaviors of dual phase steel were investigated in 3% NaCl solution at $N_f$ = $1.5\times$$10^5$ $N_f$=1.0 $\times$ $10^6$ cycles. The fatigue strength was increased with increasing the hardness of 2nd phase. The size and number of corrsion pits were influenced by the 2nd phase hardness and pits remain constant in size just after they were transited into cracks. The life of crack initiation was effected by stress level. The shape of relation of $\Delta$K and da/dn has smaller scattering in it in 3% NaCl solution than that in air. The higher the 2nd phase hardness is, the higher the corrosion fatigue life becomes. Corrosion fatigue fracture behavior was effected by mechanics in case of $N_f$=1.5$\times$10$^5$$N_f$=1.5$\times$10$^6$ cycles.

• Journal of Korean Academy of Nursing
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• v.36 no.5
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• pp.792-802
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• 2006

Purpose: The purpose of this study was to understand the adjustment process of middle-aged people in Korea with hemiplegia after a stroke. Method: For this study, the grounded theory method was utilized. Results: After constant comparative analysis, the core category emerged as 'rebuilding the body which was ruined'. In addition, the causal conditions were 'restriction of physical function', and 'loss of roles'. The adjustment process consisted of the 'facing reality phase', 'overcoming depression phase', 'overcoming physical limits phase' and 'reestablishing roles phase' The main strategies in the facing reality phase were 'holding on to a glimmer of hope', 'getting away from the harsh reality' and 'facing up to the reality'. The main strategies in the overcoming depression phase were 'soothing oneself', 'Self-introspection' and 'restoring self-esteem'. In addition, the main strategies in the self-initiative overcoming physical limits phase was 'discovering personal strategies and striving to recover'. The main strategies in the reestablishing roles phase were 'reestablishing a parents' role', 'reestablishing a spouse's role' and 'reestablishing social roles'. Conclusion: In conclusion, even though many middle aged stroke patients remained in the depression phase, most of them who overcame depression strived to conquer physical limits on their own initiative.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.241-247
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• 2015

The double-random phase encryption (DRPE) algorithm is a robust technique for image encryption, due to its high speed and encoding a primary image to stationary white noise. Recently it was reported that DRPE in the Fresnel domain can achieve a better avalanche effect than that in Fourier domain, which means DRPE in the Fresnel domain is much safer, to some extent. Consequently, a method based on DRPE in the Fresnel domain would be a good choice. In this paper we present an image-authentication method which uses only partial phase information from a double-random-phase-encrypted image in the Fresnel domain. In this method, only part of the phase information of an image encrypted with DRPE in the Fresnel domain needs to be kept, while other information like amplitude values can be eliminated. Then, with the correct phase keys (we do not consider wavelength and distance as keys here) and a nonlinear correlation algorithm, the encrypted image can be authenticated. Experimental results demonstrate that the encrypted images can be successfully authenticated with this partial phase plus nonlinear correlation technique.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.143-151
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• 2021

The purpose of our study is to confirm the trend of the muscle activity of the trunk and lower limb muscles by the attack method and phase during volleyball exercise. To achieve this purpose, spike serve and spike were conducted for 9 male middle school students, and at that time, it was divided into four phase, such as run jump, take off, impact, and follow, and the rectus abdominis, erector spine, and left rectus femoris, left biceps femoris, left anterior tibialis, left gastrocnemius midialis, right rectus femoris, right biceps femoris, right anterior tibialis, right gastrocnemius midialis, were examined. Spike serve and spike were each performed three times, and randomly cross-allocated to extract accurate data. We was no difference in all muscles according to the attack method, and the muscle activity of the rectus abdominis was highest in the impact phase and the muscle activity of the vertebral spine muscle was highest in the close-up phase. In addition, all of the measured left and right lower limb muscles showed the highest muscle activity between the assisted devices. As a result, We found out that regardless of the method of spike serve and spike, the lower limbs in the run-up phase for a high jump, the vertebrae in the take off phase, the preparation phase for hitting the ball strongly, and in the impact phase at the moment of hitting the ball. It can be seen that it exerts the greatest power in the rectus abdominis.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.4
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• pp.225-234
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• 2014

This study was carried out to investigate the sustainable agriculture of no-tillage technique including recycling of the ridge and the furrow of a field for following crops in Korea. No-tillage systems affect soil physical properties such as three phase (solid, liquid, and air phase) and distribution of soil granular. Solid ratio of subsoil in 3-year of no-tillage (NT) treatment was remarkably lower than that in conventional (CT, 2-year of no-tillage + 1-year of tillage) treatment, while air ratio of subsoil in NT remarkably increased. Bulk density of subsoil in NT remarkably decreased. Porosity of subsoil in NT remarkably increased. Deviation of air phase, bulk density, and porosity of top soil and subsoil in NT remarkably decreased in NT compared with CT. Solid phase ratio and liquid phase ratio in NT and CT had positive (+) correlation. Solid phase ratio and air phase ratio in NT and CT had negative (-) correlation, also liquid phase ratio and air ratio had negative (-) correlation. Bulk density and liquid ratio in soil had positive (+) correlation at top soil and subsoil in NT. Bulk density and air ratio in soil had negative (-) correlation in NT and CT. Porosity and liquid phase ratio had negative (-) correlation, r =1), the significant value was lower in NT than in CT. Porosity and air phase ratio had positive (+) correlation (r =1).

• Journal of the Korean Chemical Society
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• v.67 no.1
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• pp.54-63
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• 2023

In this study, six types of 2015 revised curriculum ChemistryII textbooks were analyzed for conditions, definitions, whether or not critical points were displayed, and real-life examples of phase diagram. In this study, it was confirmed that the problems pointed out in several previous studies were not reflected in the 2015 revised curriculum ChemistryII textbook. The same as the situation defining the phase diagram, the translation of the phase diagram into a phase equilibrium diagram, the distinction between phase and state being unclear, the critical point not being shown in the phase diagram, real life examples are very limited what is being presented as is suggested as a problem. Therefore, it is necessary to reflect the results of various previous studies in the revised curriculum ChemistryII textbook that will be made in the future, specify the conditions under which the phase diagram is drawn, newly model the situation defining the phase diagram, and translate the phase diagram as a 'phase diagram'. It is necessary to use the term, clarify the distinction between phase and state, mark the critical point in the phase diagram, and develop various real-life examples.