• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권6호
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• pp.1649-1667
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• 2012

In order to improve the accuracy and universality of the flow metric correlation analysis, this paper firstly analyzes the characteristics of Internet flow metrics as random variables, points out the disadvantages of Pearson Correlation Coefficient which is used to measure the correlation between two flow metrics by current researches. Then a method based on Symmetrical Uncertainty is proposed to measure the correlation between two flow metrics, and is extended to measure the correlation among multi-variables. Meanwhile, the simulation and polynomial fitting method are used to reveal the threshold value between different correlation degrees for SU method. The statistical analysis results on the common flow metrics using several traces show that Symmetrical Uncertainty can not only represent the correct aspects of Pearson Correlation Coefficient, but also make up for its shortcomings, thus achieve the purpose of measuring flow metric correlation quantitatively and accurately. On the other hand, reveal the actual relationship among fourteen common flow metrics.

• Nuclear Engineering and Technology
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• 제47권1호
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• pp.135-138
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• 2015

A new correlation predicting the idealized critical mass-flow rates of water for subcooled and saturated liquid water including two-phase water flow was developed for a wide range of upstream stagnation pressures (e.g., 0.5-20.0 MPa). A choking correction factor dependent on the upstream stagnation pressure and subcooled temperature was introduced into a new correlation, and its values were suggested to satisfy the idealized nozzle data within 10% error ranges. The suggested correlation will be instructive and helpful for related studies and/or engineering works.

• 대한의용생체공학회:의공학회지
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• 제42권4호
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• pp.143-149
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• 2021

In order to predict and prevent the disease of the abdominal aorta, which is the largest artery in the human body and the most common aneurysm, the normal arterial blood flow operation should be considered. To this end, we are trying to solve problems that may arise in the future by executing FSI based on the data obtained from 4D flow MRI. However, to match the similarity between the 4D flow MRI flow and the FSI flow, correlation was used in previous papers, but the correlation did not show the degree of agreement. Therefore, in this paper, we analyzed the correlation between the 4D flow MRI flow velocity of the human abdominal aorta and the two-way FSI flow velocity in which the three physical properties used for the aortic FSI were added to the CT abdominal aorta 3D model and the interclass correlation coefficient. As a result, the physical property M2 showed the highest similarity in correlation and intraclass correlation coefficient, and this property is intended to be helpful in the future study of the abdominal aortic two-way FSI flow rate.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1275-1283
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• 2006

Condensation heat transfer coefficients in a 7.92 mm inside diameter copper smooth tube were obtained experimentally for R22, R134a, and R410A. Working conditions were in the range of $30-40^{\circ}C$ condensation temperature, $95-410 kg/m^2s$ mass flux, and 0.15-0.85 vapor quality. The experimental data were compared with the eight existing correlations for an annular flow regime. Based on the heat-momentum analogy, a condensation heat transfer coefficients correlation for the annular flow regime was developed. The Breber et al. flow regime map was used to discern flow pattern and the Muller-Steinhagen & Heck pressure drop correlation was used for the term of the proposed correlation. The proposed correlation provided the best predicted performance compared to the eight existing correlations and its root mean square deviation was less than 8.7%.

• International Journal of Air-Conditioning and Refrigeration
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• 제9권4호
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• pp.27-36
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• 2001

A new two-phase non-boiling convective heat transfer correlation for turbulent flow $(Re_{SL}>4000)$ in vertical tubes with different fluid flow patterns and fluid combinations was developed using experimental data available from the literature. The correlation presented herein originates from a careful analysis of the major non-dimensional parameters affecting two-phase heat transfer. This model takes into account the appropriate contributions of both the liquid and gas phases using the respective cross-sectional areas occupied by the two phases. A total of 255 data points from three available studies (which included the four sets of data) were used to determine the curve-fitted constants in the improved correlation. The performance of the new correlation was compared with two-phase correlations from the literature, which were developed for specific fluid combinations.

• 한국통신학회논문지
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• 제36권6B호
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• pp.600-607
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• 2011

인터넷의 대중화로 네트워크 트래픽은 지속적으로 증가하고 복잡해지고 있다. 따라서 네트워크 자원의 효율적인 사용을 위한 응용 트래픽 분석의 중요성은 더욱 강조되고 있다. 본 논문에서는 기존 시그니쳐 기반의 인터넷 트래픽 분석 방법의 한계점을 극복하고 분석 경과의 성능 향상(분석률)을 위해 플로우 상관관계를 이용한 트래픽 분석 방법을 제안한다. 본 논문에서 제안하는 방법은 시그니쳐 기반 분석기의 결과를 입력 받아 분석된 플로우와 그렇지 않은 플로우을 간의 상관관계를 파악하고 이를 통해 분석되지 않은 플로우를 분석한다. 총 4가지(서버-클라이언트 발생 시간, 호스트-호스트, 통계) 세부 분석 방법과 이를 통합한 플로우 상관관계 기반 분석기를 제안한다. 또한 실험과 검증을 통하여 플로우 상관관계 기반 응용 분석 방법의 타당성을 증명한다.

• 대한기계학회논문집B
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• 제31권1호
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• pp.91-98
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• 2007

Air-conditioners use a spirally coiled capillary tube as an expansion device to enhance compactness of the unit. However, most empirical correlations in open literature were developed for straight capillary tubes without considering coiled effects on the mass flow rate. The objectives of this study are to investigate the flow characteristics of coiled capillary tubes and to develop a generalized correlation for mass flow rate through coiled capillary tubes. The mass flow rates through the coiled capillary tubes and straight capillary tubes were measured by varying operating conditions and tube geometry. The condensing temperatures varied at 40.5, 47.5 and $54.5^{\circ}C$, and subcoolings altered at 3.5, 6.5 and $11.5^{\circ}C$. The mass flow rates of the coiled capillary tubes decreased by 5 to 16% compared with those of the straight capillary tubes at the same operating conditions. An empirical correlation was developed by introducing equivalent length of capillary tube with non-dimensional parameters for coiled shape. The present correlation predicts the data with average and standard deviations of 0.33% and 3.24%, respectively.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 춘계학술대회 논문집(Proceeding of the KOSME 2000 Spring Annual Meeting)
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• pp.140-145
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• 2000

The objective of experimental study is to apply simultaneous measurement by PIV(Particle Image Velocimetry) to high_speed flow characteristics within ginseng cleaner model. Three different kinds of flow rate(15.20 27ℓ/min) are selected as experimental condition. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. The instantaneous velocity distribution time0mean velocity distribution and velocity profile are represented quantitatively for the deeper understanding of the flow characteristics in a ginseng cleaner model.

• 가정과삶의질연구
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• 제34권4호
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• pp.37-49
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• 2016

The purpose of this study was to examine the mediating effect of inner resilience and external resilience on the relationship between the job stress of early childhood education teachers and their teaching flow. Data were collected through questionnaires from 221 early childhood Korean teachers in the InCheon area. The instruments used in this study were the Kindergarten Teachers' Job Stress Scale, Early Childhood Teachers' Resilience Scale, and Teaching Flow Scale. The data were analyzed by Pearson's correlation analysis, multiple regression analysis, and Baron and Kenny's method. It was adapted to SPSS ver. 18.0 for Windows. This study followed a mediated effect model. First, there was a negative correlation between the job stress and teaching flow. There was a positive correlation between the teaching flow and the resilience. Secondly, there was a negative correlation with job stress and teaching flow in path model 1. In path model 2, there was a positive correlation with resilience and teaching flow. Teaching flow was statistically and significantly influenced by resilience. Thirdly, there was the mediating effect of inner resilience and external resilience on the relationship between the job stress of early childhood education teachers and their teaching flow. These results can be used as the basic data for the improvement of early childhood education teachers' teaching flow in the future.

• 설비공학논문집
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• 제8권2호
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• pp.254-266
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• 1996

Boiling heat transfer coefficients of pure refrigerants(R22, R32, R125, R134a, R290, and R600a) and refrigerant mixtures(R32/R134a and R290/R600a) are measured experimentally and compared with several correlations. Convective boiling term of Chen's correlation predicts experimental data for pure refrigerants fairly well(root-mean-square error of 12.1% for the quality range over 0.2). An analysis of convective boiling heat transfer of refrigerant mixtures is performed for an annular flow to study degradation of heat transfer. Annular flow is the subject of this analysis because a great portion of the evaporator in refrigeration or air conditioning system is known to be in the annular flow regime. Mass transfer effect due to composition difference between liquid and vapor phases, which is considered as a driving force for mass transfer at interface, is included in this analysis. Correction factor $C_F$ is introduced to the correlation for the pure substances through annular flow analysis to apply the correlation to the mixtures. The flow boiling heat transfer coefficients are calculated using the correlation considering nucleate boilling effect in the low quality region and mass transfer effect for nonzazeotropic refrigerant mixtures.