• Title/Summary/Keyword: Critical

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Correlation Development on Critical Power in a Spherical Narrow Gap (구형 간극에서의 임계 출력에 대한 상관식 개발)

  • Park, Rae-Joon;Ha, Kwang-Soon;Kim, Sang-Baik;Kim, Hee-Dong;Jeong, Ji-Hwan
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.235-240
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    • 2001
  • The CHFG (Critical Heat Flux in Gap) test results have been evaluated to quantify the critical power in hemispherical narrow gaps and a new correlation has been developed. The CHFG test results have shown that increases in the gap thickness and pressure lead to an increase in critical power. The pressure effect on the critical power was found to be much milder than predictions by CHF correlations of other researches. From the CHFG test results, a new correlation on critical power in the hemispherical gap has been developed using the non-dimensional parameters as follows: $$\frac{qCHF}{{\rho}g^hfg}{\cdot}4\sqrt{\frac{{\rho}_g^2}{g{\sigma}{\Delta}{\rho}}=\frac{0.1042}{1+0.1375({\rho}g/{\rho}l)^{0.21}(D/s)}$$ The developed correlation has been expanded to apply the spherical geometry using the Siemens/KWU's correlation.

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Kim on Critical Thinking (김영정 교수의 비판적 사고론)

  • Choi, Hoon
    • Korean Journal of Logic
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    • v.13 no.2
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    • pp.1-26
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    • 2010
  • The primary purpose of this paper is to examine critically the theory of critical thinking proposed by the late Professor Young-Jung Kim. He defined the basic properties of critical thinking as active reflectivity, and listed deepness, multilaterality and domain-transitivity as primary properties for which critical thinking aims. He, then, pursued how critical thinking can be merged with creativity and proposed the concept 'critico-creative thinking'. I argue that his theory of critical thinking has some limitation, but we can develop his critico-creative thinking further.

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Estimation of the Magnetic Field and the Critical Current of HTS BSCCO Pancake Windings (고온초전도 BSCCO 팬케이크 권선에 인가되는 자장과 임계전류의 산정)

  • Koo, Myung-Hwan;Kang, Myung-Hun;Lee, Hee-Joon;Cha, Guee-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.11
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    • pp.1970-1975
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    • 2008
  • Critical current of the superconducting machines is limited by the magnetic field. When the magnetic field is not uniform, it is difficult to estimate the magnetic field and the critical current. This paper proposed a method for the estimation of the magnetic field and the critical current of the HTS pancake windings which can be used to generate the high field magnet. A parameter which was needed to calculate the critical current of a BSCCO magnet with 10 pancake windings was obtained by the experiment. Test which was carried out by using single pancake winding and magnet consisting of 10 pancake windings shows the proposed method can be an effective method for the estimation of the critical current of pancake windings.

TIGHT TOUGHNESS CONDITION FOR FRACTIONAL (g, f, n)-CRITICAL GRAPHS

  • Gao, Wei;Liang, Li;Xu, Tianwei;Zhou, Juxiang
    • Journal of the Korean Mathematical Society
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    • v.51 no.1
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    • pp.55-65
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    • 2014
  • A graph G is called a fractional (g, f, n)-critical graph if any n vertices are removed from G, then the resulting graph admits a fractional (g, f)-factor. In this paper, we determine the new toughness condition for fractional (g, f, n)-critical graphs. It is proved that G is fractional (g, f, n)-critical if $t(G){\geq}\frac{b^2-1+bn}{a}$. This bound is sharp in some sense. Furthermore, the best toughness condition for fractional (a, b, n)-critical graphs is given.

Critical Current Estimation of HTS Magnets by using Field Dependent E-J Relation (전계를 이용한 팬케이크 권선으로 제작되는 마그넷의 임계전류 산정)

  • Kang, Myung-Hun;Koo, Myung-Hwan;Lee, Hee-Joon;Cha, Guee-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.3
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    • pp.502-508
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    • 2009
  • The method to determine the operating current of HTS magnets needs to be different from that of LTS magnets. This paper presented estimation of the critical current of pancake windings. The pancake windings can be excited by a single power source or by multiple power sources. Critical currents were determined by using field dependent E-J relation. For the better estimation of the critical current, a new method to define the magnetic field of the HTS wire has been proposed. Calculated critical currents of pancake windings were compared with measured ones of the HTS BSCCO magnet consisting of 10 pancake windings. According to the test results, the estimated critical currents of pancake windings agreed well with that of measured ones. Effects of the single and multiple power source excitation on the critical currents have been also examined.

Development and Implementation of a Critical Pathway in Patient with Osmidrosis (액취증 환자에서 표준 진료지침서의 개발과 적용)

  • Kim, Yang Woo;Kim, Heung Kyu;Shim, Kyung Won
    • Quality Improvement in Health Care
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    • v.9 no.1
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    • pp.66-73
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    • 2002
  • The current health care system demands provisions for patient care in perspectives of a cost-effectiveness and patient satisfaction. Critical pathway implementation facilitates optimal sequencing and intervention timing of patient care, and makes medical team and patients participate in a treatment actively. In this study, a critical pathway was developed and implemented to patients with osmidrosis who undertake operation. Sixty patients were included in the study. The critical pathway was implemented for care of 26 patients while the traditional care was implemented for 34 patients. In the critical pathway implemented group, time needed for charting and unessential working was reduced. Mean time amount of time for patient nursing was increased. The critical pathway implementation is an effective method to utilize time of medical team. Also it increases the satisfaction index of patients and medical team simultaneously.

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A Study of Critical Thinking Ability of Associate and Baccalaurate Degree Nursing Students (간호학생의 비판적 사고능력에 관한 연구)

  • 신경림
    • Journal of Korean Academy of Nursing
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    • v.26 no.1
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    • pp.43-52
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    • 1996
  • This descriptive study was done to investigate the critical thinking ability of senior nursing students in two types of nursing education programs : associate and baccalaureate programs. Data were conveniently collected from 159 associate degree nursing (ADN)students and 158 baccalaureate degree nursing(BSN)students. All schools were the Ministry of Education accredited and located in Seoul City and Kyung gi Province. These data were collected by self reporting questionaire given over two months from March to May, 1995. The subjects completed the Watson-Glaser Critical Thinking Appraisal (WGCTA) and a demographic questionnaire. The data was analyzed using descriptive statistics and t-test with the SAS program. The results of this study are as follows 1. The mean of critical thinking ability of the ADN students was 42.69. 2. The mean of critical thinking ability of the BSN students was 47.68. 3. There was significant difference in the WGCTA scores between the ADN and the BSN students (t=7.38 p<0.001) 4. This study suggests that critical thinking ability may increase with higher levels of nursing education. Possible explanations for these findings are discussed.

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Tunnel Safety Assessment by using the Concept of the Critical Strain in the Ground (한계변형률 개념을 활용한 터널안전성 평가)

  • Park, Si-Hyun;Park, Sung-Kun
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.571-576
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    • 2010
  • In this study, an application method of critical strains concept for tunnels' safety by using the values of measured displacements which are obtained in the field is discussed. The aim is to: (1) study on the engineering meanings of critical strains concept by reviewing the previous researches and application examples with measured displacement values; (2) study on the engineering reasonability of critical strains concept with the view point of a tunnel engineering and a geotechnical engineering; (3) study on the features of ground deformation due to tunneling and reciprocal relation between total displacement and measured displacement; (4) evaluate a tunnel safety by using domestic measurements collected in the field; and (5) re-evaluate the control criteria which were previously used in the field, with the view point of critical strains concept. Consequently, it was confirmed that critical strains in the ground has a reasonability and a possibility of unified or common concept with the view point of a tunnel engineering.

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A Study on the Choke Phenomenon of Unsteady Gas Flow through a Critical Nozzle (임계노즐을 통한 비정상 기체유동의 초크현상에 관한 연구)

  • Kim, Jae-Hyung;Kim, Heuy-Dong;Park, Kyung-Am
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.2127-2132
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    • 2003
  • A computational study is performed to better understand the choke phenomenon of unsteady gas flow through a critical nozzle. The axisymmetric, unsteady, compressible, Navier-Stokes equations are solved using a finite volume method. In order to simulate the effects of back pressure fluctuations on the critical nozzle flow, a forced sinusoidal pressure wave is assumed downstream the exit of the critical nozzle. It's frequency is 20kHz and amplitude is varied below 15% of time-mean back pressure. The results obtained show that for low Reynolds numbers, the unsteady effects of the pressure fluctuations can propagate upstream of the throat of critical nozzle, and thereby giving rise to applicable fluctuations of mass flow through the critical nozzle. The effect of the amplitude of the excited pressure fluctuations on the choke phenomenon is discussed in details.

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Correlation Verification and Revision of Critical Power in a Hemispherical Narrow Gap (구형 간극에서의 임계출력에 관한 상관식 검증 및 보완)

  • Ha Kwang-Soon;Park Rae-Joon;Kim Sang-Baik;Kim Hee-Dong
    • Proceedings of the KSME Conference
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    • 2002.08a
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    • pp.411-414
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    • 2002
  • The CHFG(Critical Heat Flux in Cap) test results have been evaluated to quantify the critical powers in hemispherical narrow gaps and Park's correlation has been verified. For verification of the Park's correlation, the critical powers in hemispherical narrow gaps have been measured using water at a pressure of 0.1-0.3 WPa for the hemispherical gap thickness of 1.0mm, and the heated top diameter of 238mm The measured critical powers were compared with Park's and Monde's correlation. As a results, the Park's correlation was most accurate of other correlations, however, estimated the critical powers somewhat larger than measured ones. So, it was suggested that the diameter factor in Park's correlation should be revised.

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