• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.789-799
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• 2012

In this research, a high temperature superconducting(HTS) motor is designed which is adequate for an electrical aircraft by generating high power density and the potentiality of its application to an aircraft is studied. The designed motor is based on YBCO plates, HTS coils composed of Bi-2223, and ironless air cooled resistive armature. The HTS motor is designed to generate power equivalent to O-360 engine with 180HP at 2700RPM which is used for Cessna and equivalent to CFM56 engine with 18000HP at 5000RPM which is used for B-737. Also, power densities of HTS motors are compared with power densities of aircraft engines so that we can estimate the potentiality of the HTS motor as an aircraft engine.

• Human Ecology Research
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• v.57 no.1
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• pp.15-26
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• 2019

This study showed that the association between solidarity and conflict is mediated by the communication of grandmothers and an adult child at the dyadic level. The common fate model (CFM) was designed to model mediation effects at the level of dyads. Participants consisted of 297 grandmother dyads and their adult child who were rearing preschool-aged grandchildren in Seoul and Gyeonggi-do. For analysis at the dyadic level, grandmothers and adults responded to the same questionnaire on the same variables. SPSS 23.0 performed descriptive statistical analysis and correlation analysis. The structural equation model (SEM) was estimated with AMOS 23.0. We tested the mediation model using the maximum likelihood method. Model fit index used the chi-square statistic, the incremental fit index (IFI), the comparative fit index (CFI), the root mean square error of approximation (RMSEA). The statistical significance of the indirect effect was examined using a bootstrapping procedure. The results are as follows. First, in the CFM, the direct effect between solidarity and conflict was significant. Therefore, the higher the solidarity, the lower conflict of grandmothers and an adult child. Second, the association between solidarity and conflict is mediated by communication at the dyadic level. Based on the results of this study, we discussed ways to strengthen the capacity of co-parenting between grandmothers and an adult child.

• Structural Engineering and Mechanics
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• v.88 no.5
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• pp.451-462
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• 2023

Lumped Damage Mechanics (LDM) is a theory proposed in the late eighties, which assumes that structural collapse may be analyzed as a two-phase phenomenon. In the first (pre-localization) stage, energy dissipation is a continuous process and it may be modelled by means of the classic versions of the theory of plasticity or Continuum Damage Mechanics (CDM). The second, post-localization, phase can be modelled assuming that energy dissipation is lumped in zones of zero volume: inelastic hinges, hinge lines or localization surfaces. This paper proposes a new LDM formulation for cracking in concrete structures in tension. It also describes its numerical implementation in conventional finite element programs. The results of three numerical simulations of experimental tests reported in the literature are presented. They correspond to plain and fiber-reinforced concrete specimens. A fourth simulation describes also the experimental results of a new test using the digital image correlation technique. These numerical simulations are also compared with the ones obtained using conventional Cohesive Fracture Mechanics (CFM). It is then shown that LDM conserves the advantages of both, CDM and CFM, while overcoming their drawbacks.

• Transactions of the Korean hydrogen and new energy society
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• v.4 no.1
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• pp.41-50
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• 1993

The hydrogen absorption and desorption characteristics of microencapsulated (CFM)$Ni_{4.7}Al_{0.2}Fe_{0.1}$ and $MmNi_4Fe$ powder with Ni and/or Cu by means of chemical plating method have been investigated. Initial hydrogen absorption rate and activation property were increased remarkably by encapsulation and subsequent compacting. Pellets abtained by compacting of Cu-encapsulated fine powder have fairly good strength even after 30 cycles of hydriding and dehydriding. Encapsulated alloy powder and their compacts show a good resistance to degradation by $O_2$ or CO in hydrogen.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1345-1351
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• 2013

Variable iron loss as function of current phase angle of Interior Permanent Magnet Synchronous Motor(IPMSM) was calculated through Curve Fitting Method(CFM). Also, a magnetic flux density distribution of iron core according to current phase angle was analyzed, and an iron loss calculation was performed including harmonic distortion. The experiment was performed by production of non-magnetizing model for the separation of mechanical loss, and the iron loss was calculated by the measurement of input using power analyzer and output power using dynamometer. Some error was generated between experimental results and calculation value, but an iron loss diminution according to current phase angle followed a same pattern. So, errors were generated by measurement, vibration, noise, harmonic distortion loss, etc.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.73-81
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.51-54
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• 2000

The traditional surface measuring method using confocal principle requires much time to measure an object surface since it is a scanning tool. In this paper, the upgraded confocal microscope is introduced. It is also a scanning tool but it requires 2D-scanning while the traditional one requires 3D-scanning. It means the time for measuring is considerably reduced. In addition, the measuring system is configured to increase the efficiency of beam. He-Ne laser whose frequency is 632.8nm is used for the laser source. An example of measuring result through the upgraded confocal microscope is showed.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.201-208
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• 1997

In order to improve the safety of nuclear power plant, we performed a human factors review for the CFMS(Critical Function Monitoring system) design of nuclear power plant. Three works were performed in this study. In first work, we developed human factors engineering program plan(HFEPP) and human factors engineering verification and validation plan (HFE-V & V plan) to effectively perform CFMS design and review. In second work, we identified human engineering discrepancies(HEDs) for CFMS design through human factors design review and proposed those resolutions. In the third work, we developed the evaluation and management methodology for identified KEDs. Methodology developed in this study can be used in other complex system as well as in CFMS design review.

• Journal of the korean veterinary medical association
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• v.34 no.6
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• pp.389-395
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• 1998

Investigation of contagious equine metritis(CFM) in 497 imported horses from several countries during 1997 was performed, and one strain of Taylorella equigenitalis was isolated from a chinese horse. To identify, we studied on the biochemical properties a

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1636-1646
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• 2011

In this paper, we implement IEEE 802.1Qay PBB-TE system and verify interoperability with the commercial PBB-TE product. In order to verify interoperability, we implement the standard protocol as well as the system integrating functions including system kernel control functions. Through interoperability tests with the commercial system, we verify the implemented protocol to perform PBB-TE TESI and ESP configurations, and protection switching as well as monitoring the results.