• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.1
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• pp.1-7
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• 2015

The traffic accidents in Korea have been increasing every year due to various reasons and simultaneously causing socioeconomic cost at the national level. This study has analyzed the correlation between meteorological factors and the traffic accidents in Seoul during 2013. Especially, we have selected season, rain and temperature among the meteorological factors to identify their significance with the traffic accidents. In addition, analysis of variance, t-test and a multiple regression technique is applied. Major findings from the analyses are discussed at the district point of view, including the different effect of weather condition and the interaction effect of rain and temperature in winter. The results of this study would be useful for developing management strategies to reduce car crashes and injury severity in Seoul.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1169-1172
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• 2006

The prices of chemical products are fluctuated by several factors. The chemical companies can't predict and be ready to all of these changes, so they are exposed to the risk of a profit fluctuation. But they can reduce this risk by making a well-diversified product portfolio. This problem can be thought as the optimization of the product portfolio. We assume that the profits come from the 'spread' between a naphtha and a chemical product. We calculate a mean and a variation of each spread and develop an automatic module to calculate the optimal portion of each product. The theory is based on the Markowitz portfolio management. It maximizes the expected return while minimizing the volatility. At last we draw an investment selection curve to compare each alternative and to demonstrate the superiority. And we suggest that an investment selection curve can be a decision-making tool.

• Korean Journal of Child Studies
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• v.26 no.4
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• pp.85-100
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• 2005

The 299(162 female and 137 male) participants in this study listened to six stories designed to elicit prosocial or self-protective rules. The Aggression Scale is composed of verbal and physical aggression and expression of anger. The Quality of Peer Relationships scale has both positive and negative components. Results showed girls used more appropriate emotional regulation strategies for managing negative emotions and more prosocial motives than boys. In the regression analysis emotional display rules and gender positive strategies accounted for 6%, 9%, and 5% of the variance in verbal aggression, physical aggression and anger expression of anger. Children with prosocial motives for emotional regulation and many strategies showed lower levels of egocentricity and peer rejection.

• Korean Journal of Child Studies
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• v.27 no.3
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• pp.169-187
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• 2006

A hierarchical linear model(HLM) provides advantages over existing traditional statistical methods (e.g., ordinary least squares regression, repeated measures analysis of variance, etc.) for analyzing multilevel/longitudinal data or diary methods. HLM can gauge a more precise estimation of lower-level effects within higher-level units, as well as describe each individual's growth trajectory across time with improved estimation. This article 1) provides scholars who study children and families with an overview of HLM (i.e., statistical assumptions, advantages/disadvantages, etc.), 2) provides an empirical study to illustrate the application of HLM, and 3) discusses the application of HLM to the study of children and families. In addition, this article provided useful information on available articles and websites to enhance the reader's understanding of HLM.

• International Journal of Knowledge Content Development & Technology
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• v.10 no.3
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• pp.21-31
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• 2020

The study examined information retrieval tools as predictors for information resources utilization, four research questions, and four hypotheses were made to guide the study. A descriptive survey was adopted for the study. Random sampling technique was used to select sample of 393 from a population of 557 academic staff registered in the University of Port Harcourt library. The questionnaire was adopted as a data collection instrument titled Information retrieval as predictors for information resources utilization (IRPIRUQ). Data were analyzed using both simple and multiple regression while analysis of variance (ANOVA) associate with regression was used for testing the hypotheses at 0.05 alpha level. The study revealed that information resources are under utilized as the OPAC and Online Databases are not easily accessed. Further findings showed that the academic staff made use of internet search engines more often than the OPAC and online databases. It was recommended among others that a new library software be installed in place of KOHA for wider connectivity and adequate distribution of software that will aid usage of the online databases and OPAC.

• Proceedings of the KIEE Conference
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• summer
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• pp.1352-1354
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• 2004

The accurate analysis on railway traction power system should be carried out a load forecast preferentially. Commonly, it has been performed through Train Performance Simulator (TPS). In the study focused on velocity or location of train, however, the electric power consumption have been computed by converting mechanical power according to given velocity. Therefore, this paper presents a development of a mathematical model for electric load. The proposed load model is expressed as polynomial to reflect the influence of variance of train speed, that is, the model expresses the power as a function of train speed. in this study, method of the least squares method is used to find each coefficient and field test is performed to acquire data, electric power and speed of train in commercial running line.

• Journal of Information Processing Systems
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• v.8 no.3
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• pp.421-436
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• 2012

Different types of fingerprint detection algorithms that are based on extraction of minutiae points are prevalent in recent literature. In this paper, we propose a new algorithm to locate the virtual core point/centroid of an image. The Euclidean distance between the virtual core point and the minutiae points is taken as a random variable. The mean, variance, skewness, and kurtosis of the random variable are taken as the statistical parameters of the image to observe the similarities or dissimilarities among fingerprints from the same or different persons. Finally, we verified our observations with a moment parameter-based analysis of some previous works.

• Current Optics and Photonics
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• v.3 no.4
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• pp.285-291
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• 2019

We have studied the behavior of light in the intermediate regime between a single nanoslit and an infinite nanoslit array. We first calculated the optical characteristics of a small number of nanoslits using finite element numerical analysis. The phase variance of the proposed nanoslit model shows a gradual phase shift between a single nanoslit and ideal nanoslit array, which stabilizes before the total array length becomes ${\sim}0.5{\lambda}$. Next, we designed a transmission-enhanced Fresnel zone plate by applying the phase characteristics from the small-number nanoslit model. The virtual-point-source method suggests that the proposed Fresnel zone plate with phase-invariant nanoslits achieves 2.34x higher transmission efficiency than a conventional Fresnel zone plate. Our report describes the intermediate behaviors of a nanoslit array, which could also benefit subwavelength metallic structure research of metasurfaces.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.5
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• pp.605-615
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• 1986

The phase-locked loop(PLL) is a communication receiver which operates as a coherent detector by continuously correcting the phase error. In this paper analysis for the Phase-error behavior of analog phase-locked loop (APLL) in the presence of additive white gaussian noise has been done theoretically and experimentally. A close form solution of the first-order loop is obtained and approximate solutions are derived for the second-order loops with RC, leadlag and perfect integrator filters. The perdormance of APLL's and their characteristics are also thoroughly investigated through experiments. In order to analyze the effect of the stochastic nature on nonlinear dynamics characteristics of the second order APLL, the phase error distribution and its variance have been obtained by using the Fokker-Planck equation. Theoretical results agree closely with those of experiment.

• Annual Conference of KIPS
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• 2022.11a
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• pp.594-596
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• 2022

Over the last decades, deep neural networks have demonstrated significant success in various tasks. To address the special vision task, choosing a hot network as backbone to extract feature is a common way in both research and industry project. However, the choice of backbone usually requires the expert experience and affects the performance of the classification task. In this work, we propose a novel idea to support backbone decision-making by exploring the feature attribution and weights distribution of hidden layers from various backbones. We first analyze the visualization of feature maps on different size object and different depth layers to observe learning ability. Then, we compared the variance of weights and feature in last three layers. Based on analysis of the feature and wights, we summarize the traits and commonalities of existing networks.