• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.8 s.251
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• pp.741-748
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• 2006

This paper numerically investigates the effects of pass arrangement on the flow distribution characteristics and the performance of a multi-pass multi-branch heat exchanger. Four cases of pass arrangement (2, 4, 6, 8 pass) are chosen to select a proper pass arrangement. A JF factor is used as an evaluation characteristic value to consider the heat transfer and the pressure drop. The present results indicate that 4-pass heat exchanger shows the best performance, and the design parameters in 4-pass heat exchanger are optimized. The design parameters are the locations of the inlet, outlet and separator, and are optimized using a response surface methodology. The JF factor of the optimum model is increased by about 9.3%, compared to that of the reference model (2-pass heat exchanger).

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.2
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• pp.41-55
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• 2006

RFID (Radio Frequency IDentification) is a wireless frequency recognition technology that can be used to recognize, trace, and Identify people, things and animals using radio frequency. Although current RFID technology can provide wide advantages in many fields, most companies do not consider widely adopting this technology yet. This paper presents RFID implementation as a technology innovation. This research selects three affecting factors of IT infrastructure, fitness of Tag, fitness of Frequency, and one moderator of the power of business partners, on RFID adoption based on innovation model, and then empirical survey is conducted among the companies using RFID technology or planing for RFID adoption to investigate the relationship of three affacting factors and one moderator factor. Reserachers can find the direction to activate RFID technology as a competitive advantage.

• Journal of Industrial Technology
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• v.27 no.A
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• pp.95-102
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• 2007

The practice of business estimate flood discharge by rainfall-flow relation that is easy collection of observation data. The important factor is rainfall, coefficient of runoff, and drainage area for analysis of runoff-flow relation. The practice of business usually use probability rainfall that use a weighted average value after each observation post estimate probability of non-same time. It has more error than same time probability rainfall, and it can excess of estimation because it can't consider space distribution of rainfall. The study of result showed similar aspect with existing ARF but width of coefficient become smaller. And the comparison of peak flow did not different what used by ARF and same time probability rainfall(A group). But non-same time probability rainfall is bigger 25% more than another(B group). Between A group and B group of the difference increased with the lapse of time.

• Research in Community and Public Health Nursing
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• v.24 no.4
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• pp.488-497
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• 2013

Purpose: The purpose of this study was to identify the construct equivalence of the general five factors of health behavior and to compare the latent means between adolescents with a health problem and those without in Korea. Methods: The 2009 KYRBS (Korean Youth Risk Behavior Survey) data were used for the analysis. Multi-group confirmatory factor analysis was performed to test whether the scale had configural, metric, and scalar invariances across the existence of health problems in adolescents. Results: Configural, metric, and factor invariances were satisfied for the latent mean analysis (LMA) between adolescents with health problem and those without. Adolescents with health problem and those without were not different in the LMA of all factors. Conclusion: Health providers should give more interest to the group of adolescents with health problems and consider prudential school life to the same group.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.157-167
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• 1999

Among several non-destructive testing methods, ultrasonic pulse velocity method and rebound index method have been widely used for the evaluation of concrete strength. However, such methods might not provide accurate estimated results since factors influencing the relationship between strength and either ultrasonic pulse velocity or rebound index are not considered. In this paper, the evaluation method of concrete strength using rod-wave velocity measured by impact-resonance method is proposed. A basic equation is obtained by the linear regression of velocity vs, strength data at specific age and then, aging factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results. Furthermore, the combined method of rod-wave velocity and rebound index is proposed.

• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.135-146
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• 1999

In this paper, we consider the Bayesian hypotheses testing for independence and symmetry in Freund's bivariate exponential model. In Bayesian testing problem, we use the noninformative priors for parameters which are improper and are defined only up to arbitrary constants. And we use the recently proposed hypotheses testing criterion called the intrinsic Bayes factor. Also we derive the arithmetic and median intrinsic Bayes factors and use these results to analyze some data sets.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1343-1351
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• 2010

Sample size determination is very important part in clinical trials because it influences the time and the cost of the experimental studies. In this article, we consider the Bayesian methods for sample size determination based on hypothesis testing. Specifically we compare the usual Bayesian method using Bayes factor with the decision theoretic method using Bayesian reference criterion in mean difference problem for the normal case with known variances. We illustrate two procedures numerically as well as graphically.

• Fashion & Textile Research Journal
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• v.7 no.5
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• pp.519-526
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• 2005

The major aim of this study was to find out the influence of brand previous knowledge, previous brand attitude, perceived quality on VMD cognition and attitude. Eight brands were selected as experimental stimuli brands for this study. A total of 320 questionnaires were obtained from college students living in Daegu. Using factor analysis, each of brand previous knowledge, previous brand attitude, perceived quality, VMD attitude were extracted one factor.VMD cognition were divided into 5 factors; Coordination, Attractiveness, Fashionability, Fitness, and Functionality. The results revealed that previous brand attitude and perceived quality affected VMD cognition and VMD attitude, while brand previous knowledge did not affect VMD cognition and VMD attitude. Therefore, when companies related to fashion investigate the effect of VMD, they should consider the previous brand attitude and perceived quality of their brands.

• Geomechanics and Engineering
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• v.3 no.2
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• pp.153-167
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• 2011

Traditional design methods of bearing capacity of shallow foundations are deterministic in the sense that they do not explicitly consider the inherent uncertainty associated with the factors affecting bearing capacity. To account for such uncertainty, available deterministic methods rather employ a fixed global factor of safety that may lead to inappropriate bearing capacity predictions. An alternative stochastic approach is essential to provide a more rational estimation of bearing capacity. In this paper, the likely distribution of predicted bearing capacity of strip footings subjected to vertical loads is obtained using a stochastic approach based on the Monte Carlo simulation. The approach accounts for the uncertainty associated with the soil shear strength parameters: cohesion, c, and friction angle, ${\phi}$, and the cross correlation between c and ${\phi}$. A set of stochastic design charts that assure target reliability levels of 90% and 95%, are developed for routine use by practitioners. The charts negate the need for a factor of safety and provide a more reliable indication of what the actual bearing capacity might be.

• Proceeding of EDISON Challenge
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• 2016.11a
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• pp.101-105
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• 2016

Prandtl's Lifting-line theory is the classical theory of calculating aerodynamic properties. Though it is classical method, it predicts the aerodynamic properties well. By lifting-line theory, high aspect ratio is critical factor to decrease induced drag. And 'elliptic-similar' wing also makes the minimum induced drag. But due to the problem of manufacturing, tapered wing is preferred and have been utilized. In this Paper, by using Edison CFD, verifying the classical lifting-line theory. To consider induced drag only, using Euler equation as governing equation instead of full Navier-Stokes equation. Refer to the theory, optimum taper ratio which makes the minimum induced drag is 0.3. Utilizing the CFD results, plotting oswald factor over various taper ratio and investigating whether the consequences are valid or not. As a result, solving Euler equation by EDISON CFD cannot guarantee the theoretical values because it is hard to set the proper grid to solve. Results are divided into two cases. One is the values are decreased gradually and another seems to following tendency, but values are all negative number.