• Journal of the Korean Data and Information Science Society
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• v.17 no.2
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• pp.421-436
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• 2006

Huang proposed a grey-based nearest neighbor approach to predict accurately missing attribute value in 2004. Our study proposes which way to decide the number of nearest neighbors using not only the deng's grey relational grade but also the wen's grey relational grade. Besides, our study uses not an arithmetic(unweighted) mean but a weighted one. Also, GRG is used by a weighted value when we impute missing values. There are four different methods - DU, DW, WU, WW. The performance of WW(Wen's GRG & weighted mean) method is the best of any other methods. It had been proven by Huang that his method was much better than mean imputation method and multiple imputation method. The performance of our study is far superior to that of Huang.

• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.1909-1915
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• 2004

The hermetic rotary compressor is one of the most important components of an air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration occurs due to gas pulsation during the compression process and to unbalanced dynamic force. In order to reduce noise and vibration, it is necessary to identify their sources and transmission path and effectively control them. Many approaches have been tried in order to identify the noise transmission path of a compressor. However, identification has proven to be difficult since the characteristics of compressor noise are complicated due to the interaction of the compressor parts and gas pulsation. In this study, the statistical energy analysis has been used to trace the energy flow in the compressor and to identify the transmission paths from the noise source to the exterior sound field.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.3
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• pp.138-142
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• 2005

In this paper, we compared recognition rates between NN(neural networks) and clustering method as a scheme of off-line PD(partial discharge) diagnosis which occurs at the stator coil of traction motor. To acquire PD data, three defective models are made. PD data for classification were acquired from PD detector. And then statistical distributions are calculated to classify model discharge sources. These statistical distributions were applied as input data of two classification tools, BP(Back propagation algorithm) and ANFIS(adaptive network based fuzzy inference system) pre-processed FCM(fuzzy c-means) clustering method. So, classification rate of BP were somewhat higher than ANFIS. But other items of ANFIS were better than BP; learning time, parameter number, simplicity of algorithm.

• Journal of the Korean School Mathematics Society
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• v.26 no.1
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• pp.21-47
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• 2023

This study examines the activity system of teaching and learning about informal statistical inference using sampling simulation, based on cultural-historical activity theory. The research explores what contradictions arise in the activity system and how the system changes as a result of these contradictions. The participants were 20 elementary school students in the 5th to 6th grades who received classes on informal statistical inference using sampling simulations. Thematic analysis was used to analyze the data. The findings show that a contradiction emerged between the rule and the object, as well as between the mediating artifact and the object. It was confirmed that visualization of empirical sampling distribution was introduced as a new artifact while resolving these contradictions. In addition, contradictions arose between the subject and the rule and between the rule and the mediating artifact. It was confirmed that an algorithm to calculate the mean of the sample means was introduced as a new rule while resolving these contradictions.

• Journal of the Korean Statistical Society
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• v.25 no.1
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• pp.111-122
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• 1996

A model for a system whose state changes continuously with time is introduced. It is assumed that the system is modeled by a Brownian motion with negative drift and an absorbing barrier at the origin. A repairman arrives according to a Poisson process and repairs the system according to an (s,S) policy, i.e., he increases the state of the system up to S if and only if the state is below s. A partial differential equation is derived for the distribution function of X(t), the state of the system at time t, and the Laplace-Stieltjes transform of the distribution function is obtained by solving the partial differential equation. For the stationary case the explicit expression is deduced for the distribution function of the stationary state of the system.

• Journal of Korean Society for Quality Management
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• v.37 no.2
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• pp.12-21
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• 2009

Organizations worldwide have implemented quality management system, ISO 9001:2000 and environmental management system, ISO 14001:2004. Researches have been conducted regarding occupational health and safety management system, integration of these management systems, and extension to corporate social responsibility and sustain ability management system, ISO 26000. This paper examines quality and environment management systems for machinery and metal companies using audit results. We perform statistical tests to see if there are any significant differences of minor nonconformities for requirements of ISO 9001:2000 and ISO 14001:2004 based on implementation motive, operating periods, and organization's size. We also present causes and reasons for statistical differences and minor nonconformities to use as references for implementing efficiently quality management system and environment management system.

• Journal of Korean Society of Forest Science
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• v.95 no.5
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• pp.605-613
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• 2006

The goal of this study was to propose building strategies of web-based national park monitoring system (WNPMS) using geographic information analysis system. To accomplish this study, at first, this study selected and made integrated management indicators considering physical, ecological, and socio-psychological carrying capacity in national park. Secondly, this study built up an integrated management this system with statistical analysis program for execution of various multivariate analysis and spatial analysis. Finally, WNPMS could identify the relationship among visitors, natural resources, and recreation facilities in national park, and forecast the future management status of each national park in Korea. There results of this study will contribute to prevent the damage of natural resources and facilities, improve visitor's satisfaction, prevent an excess of carrying capacity at national park, and established tailored management strategies of each national park.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2017.11a
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• pp.72-72
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• 2017

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7870-7877
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• 2015

In the case of CWR (Continuous welded rail) located on the railway bridge, the CWR has additional axial force due to interaction of bridge and track. Therefore, the CWR tracks located on the bridge have to secure the safety of running train and CWR track through mitigating influence for interaction of bridge and track. The railway design guide in Korea (KR C-08080) provides a certain value for property of longitudinal friction behavior of rail fastening system that is major parameter of interaction behavior by applying European codes. However, in order to apply to domestic railway, it is necessary to review property characteristics of the rail fastening system in actual use. In this paper, the experiment for longitudinal friction behavior of rail fastener applied to concrete track on the railway bridge in Korea was carried out, and statistical characteristic for property of the rail fastener was analyzed from the result of the experiment.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.573-584
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• 2021

Background and objective: This study was conducted with 10 men and women in their 50s-60s to investigate the effect of agro-healing activities on the improvement of mental health. Methods: The experimental group participated in total 8 sessions of agro-healing activities, once a week for 2 hours each, at a care farm in Wanju-gun. Physiological measurements were taken with an electroencephalogram (EEG), Salivettes samples, and blood pressure before and after the activities. Results: As a result of analyzing the changes in brainwaves of the experimental group before and after agro-healing activities, relative slow alpha (RSA), relative fast alpha (RFA), and ratio of alpha to high beta (RAHB), the indices of stability and relaxation, increased after the program with statistical significance. Also, the ratio of SMR to theta (RST) of the attention index increased on the right frontal lobes, temporal lobes, and left occipital lobes, and relative low beta (RLB) increasd on the frontal lobes, temporal lobes, and occipital lobes after the program with statistical significance. The sympathetic nervous system activity, which is a stress index, decreased after the program, whereas the parasympathetic nervous system activity, which is a relaxation index, increased, showing statistical significance (p < .05). As a result of analyzing the changes in blood pressure after the program, systolic blood pressure and diastolic blood pressure decreased from prehypertension to normal blood pressure, showing statistical significance. SThese results indicate that participating in agro-healing activities at a care farm for the 50-60s helps reduce stress and improve stability and relaxation as well as attention. Conclusion: Thus, developing and applying customized agro-healing programs for participants will have a positive effect on brain activity and psychophysiological improvement by relieving tension and stress. However, there are limitations in generalizing the results of this study since most of agro-healing farms have low accessibility that leads to a low level of participants.