• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.58-63
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• 1992

Effects of the second sintering process on the superconducting characteristics of the (Bi, Pb)SrCaCuO system have been studied. It was found that the optimal calcining temperature of mixed powder may be proper to 820$^{\circ}C$ and the optimal sintering temperture was determined on 845$^{\circ}C$. The 2212 phases transitioned the 2223 phasses during the sintring process and zero resistance was attained at 108 K for the samples sintered for 264 hr. The 2223 phases changed into the 2212 phases and nonsuperconducting phases by the second grinding process. And the 2223 phases did not recover easily by the second sintering process.

• Korean Journal of Materials Research
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• v.13 no.11
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• pp.756-760
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• 2003

Two dimensional computer simulations were conducted on percolative structure in which second phases with various short diameter were arranged in matrix phase. In case of prohibiting the overlap among the second phases, the maximum area fraction of second phase arranged in matrix was increased with higher short diameter. In case of allowing the overlap among the second phases, the critical area fraction was increased with higher short diameter and the total number of distributed second phase was decreased. This results represented that thickness variation of short diameter by grain growth on the production processes affect significantly forming the completion path.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.929-935
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• 2001

Two-dimensional computer simulations were conducted on percolation structure in which second phases of various aspect ratios were arranged in a lattice (matrix). The second phases were randomly arranged in an array with two different computational programs; one prohibiting an overlap among second phases and the other allowing the overlap. From the simulation prohibiting the overlap, it was predicted that a complete path was formed at less amounts of the second phase with higher aspect ratios. In the simulation allowing the overlap, a complete path throughout the array was formed by arranging the second phase of an aspect ratio of 1. 5, 20, 100 with less than 59%, 43%, 19%, 4% in the array, respectively.

• Journal of Technologic Dentistry
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• v.23 no.2
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• pp.161-170
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• 2002

The Purpose of this study was to investigate the chemically improvement of metal-ceramics bond strength in the course of recasting Ni-Cr metal composite system with 10wt.%, 20wt.% and 30wt.% aluminum respectively. We have tested the bond strength, micro-structure, chemical composition of each metal composites and metal- ceramic bond interfaces by 3-point bending strength tester, SEM and EDS. We have made the conclusions through this study as follow: 1. The most suitable amount of aluminum to the Ni-Cr metal composite recasting is 20wt. % for improving metal-ceramics bond strength with debonding strength value of 49.54 kgf/mm2. 2. The aluminum must be changed to small spread alumina like phases and second aluminum-metal composites phases in the morphology of Ni-Cr metal composite system by adding during it's casting. These second phases have inclined functional oxide phases mixed with metal elements and they must take roll to improvement of metal-ceramics bond strength. 3. In the case of 30wt.% aluminum appended to Ni-Cr metal composite system, an excess of second inclined functional oxide phases produce cracks and spalling of them apart from it's base material. It must be a important factor of reduction of metal-ceramics bond strength.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.343-350
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• 2003

Using Bi$_2$Sr$_2$Ca$_2$.$_2$Cu$_3$ $O_{x}$ powders prepared by solid state reaction and spray drying method, the nucleation and growth behaviors of superconducting and second phases were investigated during isothermal heat treatment. When the spray drying power was used in contrast with solid state reaction powder, Bi$_2$Sr$_2$Ca$_2$.$_2$Cu$_3$ $O_{x}$ (2223) phase could be formed at the relatively shot time and second phases were much bigger. Quantitative analysis showed that as the heat treatment time increased, more Bi$_2$Sr$_2$Ca$_2$.$_2$Cu$_3$ $O_{x}$ (2212) changed to 2223 and the major second phase was changed from (Sr,Ca)$_{14}$Cu$_{24}$ $O_{x}$(14:24) to (Sr,Ca)$_2$Cu$_1$ $O_{x}$ (2:l). The superconducting phase formed at the relatively short time 14:24 phase. Following the Bi-free phase of 14:24 Phase, but long time was needed in places far from the 14:24 phase. Following the formation of the 2212 phase near the 14:24 phase, the 2223 phase nucleated preferentially at the interface between the 2212 and 14:24 phases. The preferential nuclcation of 2223 was explained by its structural similarity and low Interfacial energy with both the Bi-free and 2212 Phases.12 Phases.

• Journal of the Korean Ceramic Society
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• v.27 no.3
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• pp.423-429
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• 1990

YBa2Cu3Ox ceramics superconductors fabricated using solid state reaction usually contain second phases, such as BaCuO2 and CuO. These second phases are located long the grain boundaries and enhance the abnormal growth of YBa2Cu3Ox grains and, consequently, generate the microcracks. These second phaases were reduced by adding Y2BaCuO5 into solid state reacted YBa2Cu3Ox ceramics. Y2BaCuO5 reacts with grain boundary second phases and reduces the grian size of the ceramics. It was observed the critical current density was improved by adding Y2BaCuO5 into solid state reacted YBa2Cu3Ox ceramic superconductor.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.2
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• pp.97-104
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• 2003

The structural transitions of the matrix and the second phases of $Ti_{1.0}Mn_{0.9}V_{1.1}$ and $Ti_{1.0}Cr_{1.5}V_{1.7}$ alloys upon hydrogenation have been investigated at 293K. The effect of hydrogen isotope on their crystal structures has been also discussed. The crystal structures, Phase abundance and lattice parameters of the hydrides were determined by the Rietveld method using X-ray diffraction data. At the experimental temperature, the $Ti_{1.0}Mn_{0.9}V_{1.1}$ alloy and $Ti_{1.0}Cr_{1.5}V_{1.7}$ alloy revealed different structural transition processes upon hydrogenation although the crystal structures of these two alloys are both BCC at room temperature. The second phases such as Ti-rich phase with $NiTi_2$ structure and $\alpha$-Ti with HCP structure absorbed hydrogen at relatively low hydrogen pressures and the phase abundance remained almost constant. This means that it is desirable to decrease the amount of the second phases as far as possible in order to increase the effective hydrogen storage capacities of the alloys. The crystal structures of corresponding isotope hydrides, the phase abundance and the lattice parameters did not depend on the kind of hydrogen isotope, but only on the hydrogen content.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.880-885
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• 2003

Research in this paper focuses on the kinetic evaluation of swelling of the liquid crystalline phases of glyceryl monooleate (GMO). Swelling of the lamellar and cubic liquid crystalline phases of GMO was studied using two in vitro methods, a total immersion method and a Franz cell method. The swelling of the lamellar phase and GMO having 0 %w/w initial water content was temperature dependent. The swelling ratio was greater at $20^{\circ}^C than 37^{\circ}^C$ . The water uptake increased dramatically with decreasing initial water content of the liquid crystalline phases. The swelling rates obtained using the Franz cell method with a moist nylon membrane to mimic buccal drug delivery situation were slower than the total immersion method. The swelling was studied by employing first-order and second-order swelling kinetics. The swelling of the liquid crystalline phases of GMO could be described by second-order swelling kinetics. The initial stage of the swelling (t < 4 h) followed the square root of time relationship, indicating that this model is also suitable for describing the water uptake by the liquid crystalline matrices. These results obtained from the current study demonstrate that the swelling strongly depends on temperature, the initial water content of the liquid crystalline phases and the methodology employed for measuring the swelling of GMO.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.1 s.256
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• pp.29-39
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• 2007

A second-moment closure is applied to the prediction of a homogeneous turbulent shear flow laden with mono-size particles. The closure is curried out based on a 'two-fluid' methodology in which both carrier and dispersed phases are considered in the Eulerian frame. To reduce the number of coupled differential equations to be solved, Reynolds stress transport equations and algebraic stress models are judiciously combined to obtain the Reynolds stress of carrier and dispersed phases in the mean momentum equation. That is, the Reynolds stress components for carrier and dispersed phases are solved by modelled transport equations, but the fluid-particle velocity covariance tensors are treated by the algebraic models. The present predictions for all the components of Reynolds stresses are compared to the DNS data. Reasonable agreements are observed in all the components, and the effects of the coupling of carrier and dispersed phases are properly captured in every aspects.

• Journal of East-West Nursing Research
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• v.1 no.1
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• pp.82-98
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• 1997

The purpose of this study was to determine pattern of the stress perceived by stroke patients over time. The ultimate goal of the research is to provide data to help nurses to design the plan of nursing care of the stroke patients both in the hospital and at home. A total of 57 admitted stroke patients were collected from one general hospital in Seoul from June, 12 to September, la, 1993. The data were collected for three phases(within one week after leaving the hospital). The tools for this study, three scales were used ; Stress scale developed by the investigator. Constitution classifing scale designed by Kho(1984), and Self-care measuring scale by Kang(1984). Data were analyzed in four steps using statistical analysis. First, demographic data were determined by descriptive statistics. Second. the pattern of stress perceived by stroke patients across three phases was measured using repeated measures ANOVA. Third, stress of stroke patients classified by constitution, paralyzed area. and attack frequency were measured using ANOVA or t-test, and the pattern of stress by group over time was determined using paired t-test in post hoc test. Fourth. Pearson correlation coefficients were calculated to determine the relationship between the stress and self-care activities. The results of this study are ; 1. The pattern of stress across three phases ; There was a decrease of the stress across three phases. In general. psychological stress as the highest among three phases(F=36.92. P=.000). There was a statistically significant difference of the physical stress(F=34.55, p=.000), the psychological stress (F=15.49, p=.0005) and the social stress (F=24.71. p=.000) among three phases. There was a statistically significant difference of the stress between the first phase (on admission) and the second phase(before leaving the hospital) and was a decrease of the stress (t =6.36. p=.000). 2. The pattern of stress of stroke patients classified by constitution across three phases ; Stroke patients classified as So-Eum perceived the highest stress among three groups(Tae-Eum, So-Eum. So-Yang). There was no statistically significant difference of stress according to the constitution of stroke patients among three phases. Hence. stress was not influenced by the constitution of stroke patients, but there was a statistically significant difference of stress over time. 3. The pattern of stress of stroke patients classified by the paralyzed area across three phases ; Right paralyzed stroke patients perceived higher stress than left paralyzed stroke patients. There was, however, no statistically significant difference of stress between two groups except 2nd phase. There was no statistically significant difference of the perception of stress bet ween the right and left paralyzed stroke patients. 4. The pattern of stress of stroke patients classified by the frequency of the relapse of the disease across three phases ; Stress was higher in stroke patients who had the relapse of the disease twice more than the first time. There was, however, no statistically significant difference of stress between two groups. There was no statistically significant difference of stress of stroke patients according to the relapse of the disease among three phases. Hence, stress was no influenced by the relapse of the disease. 5. The relationship between the stress and self-care activities ; There was a negative relationship between the stress and self-care activities each phase(on admission, r= -.1563 ; before leaving the hospital, r= -.4030 ; after leaving the hospital, r= -.5291). Hence, the higher the self-care activities, the lower the stress. This study has three important findings. First finding was that psychological stress perceived by stroke patients was the highest among three phases. The second finding was that factors such as the constitution, the paralyzed area, and the relapse of the disease did not have an influence on the stress perceived by stroke patients across three phases(on admission, before leaving the hospital, after leaving the hospital). There was a statistically significant decrease of the stress perceived by stroke patients across three phases. The third finding was that there was a negative relationship between the self-care ability and stress. In this study, these findings have implications for nursing care for the rehabilitation of stroke patients and suggest the need of nursing intervention to promote the self-care ability and to support the psychological self-esteem of stroke patients.