• 제목/요약/키워드: F.E. Model

검색결과 607건 처리시간 0.029초

AC susceptibility of the $high-T_c$ superconductor $SmBa_2Cu_2O_y$ (고온초전도체 $SmBa_2Cu_2O_y$ 교류자화율)

  • Kim H;Lee B. Y;Lee J. H;Kim Y. C
    • Progress in Superconductivity
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    • 제6권1호
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    • pp.89-94
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    • 2004
  • The policrystalline$SmBa_2$$Cu_2$$O_{y}$ was synthesized by the solid state reaction method. The dependence of AC susceptibility on temperature and applied ac field was studied. The critical temperature $T_{c}$ is about 92 K. As the ac field is increased, the slope and the value of real part of susceptibility become smaller and the peak position of imaginary part $T_{P}$ was shifted to a lower temperature with peak broadening. Using Bean's model, we determined intergrain critical current density $J_{c}$ and obtained $44 A/{cm}^2$ at 75 K. From the relation of the $J_{c}$ (T)=($1-T/T_{c}$ )$^{\beta}$ we obtained $\beta$=0.8 and found that the Josephson junction type of the $SmBa_2$$Cu_2$$O_{y}$ is SIS junction. The peak of the imaginary part shifts to higher temperature with increasing frequency, f. from Arrhenius plot, we obtained the activation energy of about 0.96 eV.

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Study on efficient financial income elderly long-term care facilities size

  • Jeong, Seong-Bae
    • Journal of the Korea Society of Computer and Information
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    • 제21권10호
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    • pp.157-166
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    • 2016
  • The aims of this study are to contribute to efficient revenue management by analysis of the scale in elderly long-term care facilities. The data was used for input of the elderly long-term care costs Scale, and calculated the staffing standards and social welfare facilities workers with living wage guidelines in the Department of Health and Human Services. Revenue efficiency is the highest order of size are as follows. I8(98 people) \43,517,010, H6(86 people) \36,568,332, G8(78 people) \29,426,532, F8(68 people) \23,227,532, E8(58 people) \19,701,254, D8(48 people) \19,155,187, C6( 36) \14,389,109, B8(28 people) \9,920,031, A8(18 people) \3,721,031. It seems that its revenue efficiency even higher than the larger the scale. Meanwhile, The researchers focused on C6 (36 patients) model. Suggestion of this study are following; First, the arrangement can be provided based on needs of the elderly care facility staffing standards. Secondly, an elderly care facility selected wage guidelines. Thirdly, the elderly efficiency guidelines established by the size of a nursing facility. This study and other financial income factor are not the applicable limits.

A study on the magnetic properties of high Tc superconductor $Y_{1-x}Yb_xBa_2Cu_3FyOy$ (고온 초전도체 $Y_{1-x}Yb_xBa_2Cu_3FyOy$의 자기적 성질에 관한 연구)

  • 김재욱;김채옥
    • Electrical & Electronic Materials
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    • 제9권6호
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    • pp.578-583
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    • 1996
  • The magnetic properties have been investigated for the system of $Y_{1-x}$Yb$_{x}$Ba$_{2}$Cu$_{3}$F$_{y}$O$_{y}$ with x=0.0, 0.1, 0.2, 0.3, 0.4 and 0.5. In the magnetic hysteresis measurements, the values of the magnetic critical current densities are in the range of 10$^{4}$-10$^{5}$ A/cm$^{2}$ at the maximum external field 1.4 T. The upper critical field is over 100 T. The critical current density is estimated by the magnetization width .DELTA.M through the Bean critical state model. As the field strength is increased, the .DELTA.M diminishes slowly. The .DELTA.M for the fluorinated sample also decreases slowly with increasing field. It is considered that the large J, value results from this type is due to enhanced pinning center in grain boundary.y.ary.y.

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The Influence of Personality Characteristics and Decision Making Type on Self-Leadership of Nursing Students (간호대학생의 성격특성과 의사결정유형이 셀프리더십에 미치는 영향)

  • Kim, Myoung Sook
    • The Journal of Korean Academic Society of Nursing Education
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    • 제22권4호
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    • pp.441-451
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    • 2016
  • Purpose: This study aimed to examine the effects of personality characteristics and decision making type on the self-leadership of nursing students. Methods: The participants were 336 nursing students using a self-report questionnaire. Data were analyzed using a t-test, ANOVA, $Scheff{\acute{e}}$ test, Pearson correlation coefficients, and stepwise multiple regression. Results: There were significant positive correlations between self-leadership and extraversion (r=.50, p<.001), agreeableness (r=.22, p<.001), conscientiousness (r=.60, p<.001), openness to experience (r=.36, p<.001), and rational style (r=.47, p<.001). However the correlation between self-leadership and dependent style was significantly negative (r=-.11, p=.044). Conscientiousness (${\beta}$=.60, p<.001), extraversion (${\beta}$=.28, p<.001), and rational style (${\beta}$=.21, p<.001), openness to experience (${\beta}$=.18, p<.001), and degree of leadership level (${\beta}$=.10, p=.020) were identified as factors affecting self-leadership. The explanation power of this regression model was 50.0% and it was statistically significant (F=67.52, p<.001). Conclusion: The results of this study indicated that effective self-leadership programs should be developed by including conscientiousness, extraversion, openness to experience, and rational decision making.

Study on the Vibration of Diesel Engine Generator of Drill Ship (드릴쉽 디젤엔진 발전기의 진동에 관한 연구)

  • Jin, Bong-Man;Park, Hyung-Sik;Do, Cheon-Soo;Kong, Young-Mo;Kim, Nho-Seong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 한국소음진동공학회 2009년도 춘계학술대회 논문집
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    • pp.504-508
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    • 2009
  • To obtain high power, diesel engines continuously increase combustion pressure and mean effective pressure each cylinder, and the excitation sources and noisy sources are increased, too. Moreover, to reduce the costs, shipyards make hull structures weaker than before. As above reasons, it is more difficult to control the vibration phenomenon nowadays. In this study, it was investigated why diesel generator sets reached the vibration allowable limits during the FAT and heavy vibration phenomenon of diesel generator sets using ODS test during onboard tests. Also, it is found out the stiffness of deck and common bed using the test result of their structural impedance. To find out the vibratory characteristics of diesel generator sets, MODAL tests were carried out. From the sensitivity analysis after above tests, it was selected points to be reinforced and studied troubleshooting to solve heavy vibration phenomenon of diesel generator sets.

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Effects of Angular Velocity Change on the Flow Field and Heat Transfer in the Bridgman Crystal Growth Process (Bridgman 결정성장공정에서 각속도변화가 유동장 및 열전달에 미치는 영향)

  • 문승재;노승탁
    • Transactions of the Korean Society of Mechanical Engineers
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    • 제19권3호
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    • pp.771-783
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    • 1995
  • A simplified model for the so-called ACRT(accelerated crucible rotation technique) Bridgman crystal growth was considered in order to investigate the principal effects of the periodic variation of angular velocity. Numerical solutions were obtained for Ro=0.5, Ra=4.236*10$_{6}$ and E=2.176*10$^{-3}$ . The effects of spin-up process combined with natural convection was investigated as a preliminary study. The spin-up time scale for the present problem was a little larger than that observed for homogeneous spin-up problems. Numerical results reveal that over a time scale of (H$^{2}$/.nu..omega.$_{f}$)$^{1}$2/ the forced convection due to the formation of Ekman layer predominates. When the state of rigid body rotation is attained, natural convection due to buoyancy emerges as the main driving force and them the steady-state is approached asymptotically. Based on our preliminary results with simple spin-up, several fundamental features associated with variation of rotation speed are successfully identified. When a periodic variation of angular velocity was imposed, the system response was also periodic. Due to effect of mixing, the heat transfer was enlarged. From the analysis of time-averaged Nusselt number along the bottom surface the effect of a periodic variation of angular velocity on the interface location could be indirectly identified.d.

Thermophysical Properties of Acetophenone with Ethylchloroacetate at Temperatures of 303.15, 313.15 and 323.15 K

  • Saravanakumar, K.;Baskaran, R.;Kubendran, T.R.
    • Journal of the Korean Chemical Society
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    • 제56권4호
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    • pp.424-430
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    • 2012
  • Densities, viscosities, refractive indices and speed of sounds of the binary mixtures of Acetophenone with Ethylchloroacetate were measured over the entire mole fractions at (303.15, 313.15 and 323.15) K. From these experimental results, excess molar volume $V^E$, viscosity deviation ${\Delta}{\eta}$, refractive index deviation ${\Delta}n_D$, deviations in speed of sound ${\Delta}u$, deviations in isentropic compressibility ${\Delta}k_s$ and excess intermolecular free length ${\Delta}L_f$ were calculated. The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind et al., Tamura and Kurata, Katti and Chaudri, Sedgwick, Krishnan-Laddha and McAllister. The thermo physical properties under study were fit to the Jouyban-Acree model. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. It was found that in all cases, the data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.

Three Dimensional Dynamic Analysis of High-Tc Superconducting Revolving Field Type Synchronous Motor (고온초전도 회전계자형 동기전동기의 3차원 동특성 해석)

  • Lee, Sang-Jin
    • Proceedings of the KIEE Conference
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    • 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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    • pp.438-441
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    • 1999
  • One of the most important aspect in developing High-Tc Superconducting Synchronous Motor is producing high-Tc superconducting tapes that withstand the amount of currents that is needed to run the motor with stability. The purpose of this paper is to find the magnetic field distribution inside the motor in order to find out if the high-Tc superconducting tapes operate stably in actual motor operation. With this goal, magnetic field distribution in a detailed model of the actual motor was analyzed through F.E.M. By analyzing the field distribution acquired through the computer simulation, it has been observed whether the high-Tc superconducting tape maintains its superconductivity in actual motor operation. Also, the effects of the flux damper on the motor's operational characteristics and the magnetic field distribution have been analyzed. As a result, it has been proved that the high-Tc superconducting tapes can withstand 600 A turns which is required by the previous simulation aimed at developing this motor. It has also seen that the flux damper reduces armature reactance during the motor operation and change of load, helping the stable motor operation.

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Development of Hybrid Method for the Prediction of Internal Flow-induced Noise and Its Application to Throttle Valve Noise in an Automotive Engine

  • Cheong, Cheol-Ung;Kim, Sung-Tae;Kim, Jae-Heon;Lee, Soo-Gab
    • The Journal of the Acoustical Society of Korea
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    • 제22권4E호
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    • pp.183-196
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    • 2003
  • General algorithm is developed for the prediction of internal flow-induced noise. This algorithm is based on the integral formula derived by using the General Green Function, Lighthill's acoustic analogy and Curl's extension of Lighthill's. Novel approach of this algorithm is that the integral formula is so arranged as to predict frequency-domain acoustic signal at any location in a duct by using unsteady flow data in space and time, which can be provided by the Computational Fluid Dynamics Techniques. This semi-analytic model is applied to the prediction of internal aerodynamic noise from a throttle valve in an automotive engine. The predicted noise levels from the throttle valve are compared with actual measurements. This illustrative computation shows that the current method penn its generalized predictions of flow noise generated by bluff bodies and turbulence in flow ducts.

Further Investigations on the Financial Attributes of the Firms listed in the KOSDAQ Stock Market

  • Kim, Hanjoon
    • International Journal of Contents
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    • 제9권2호
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    • pp.27-37
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    • 2013
  • From the perspective of the domestic capital markets, there have been few researches on the financial characteristics of the firms belonging to the KOSDAQ(Korea Securities Dealers Automated Quotation) market, in comparison with those of the firms in the KOSPI. This study has performed three hypothesis tests to obtain the following results: By employing the 'panel data' analysis, it was found that, for the book-value based leverage, all of the six proposed IDVs were statistically significant as the financial determinants of leverage, across the two proxies measuring profitability (i.e., PFT and ROE), while all of the IDVs except VOLATILITY, also seemed to be the attributes to explain the market based dependent variable in the model with the PFT. Moreover, there may be statistically significant (structural) changes (or quasi-experiment) ) between the pre- and post-U.S. financial crisis in the year of 2008, when measured the leverage with the market-value basis with utilizing the Chow F-test. Finally, based upon the logistic regression results, the probability for a firm to be classified into the Prime section in the KOSDAQ market, may be higher, as its profit margin and asset turnover increase.