• Communications for Statistical Applications and Methods
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• 제28권6호
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• pp.595-610
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• 2021

Recently a few articles have derived robust first-order rotatable and D-optimal designs for the lifetime response having distributions gamma, lognormal, Weibull, exponential assuming errors that are correlated with different correlation structures such as autocorrelated, intra-class, inter-class, tri-diagonal, compound symmetry. Practically, a first-order model is an adequate approximation to the true surface in a small region of the explanatory variables. A second-order model is always appropriate for an unknown region, or if there is any curvature in the system. The current article aims to extend the ideas of these articles for second-order models. Invariant (free of the above four distributions) robust (free of correlation parameter values) second-order rotatable designs have been derived for the intra-class and inter-class correlated error structures. Second-order rotatability conditions have been derived herein assuming the response follows non-normal distribution (any one of the above four distributions) and errors have a general correlated error structure. These conditions are further simplified under intra-class and inter-class correlated error structures, and second-order rotatable designs are developed under these two structures for the response having anyone of the above four distributions. It is derived herein that robust second-order rotatable designs depend on the respective error variance covariance structure but they are independent of the correlation parameter values, as well as the considered four response lifetime distributions.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.261-279
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• 2023

In this article, the uplink achievable rate is investigated for massive multiple-input multiple-output (MIMO) under correlated Ricean fading channel, where each base station (BS) and user are both deployed multiple antennas. Considering the availability of prior knowledge at BS, two different channel estimation approaches are adopted with and without prior knowledge. Based on these channel estimations, a two-layer decoding scheme is adopted with maximum ratio precoding as the first layer decoder and optimal second layer precoding in the second layer. Based on two aforementioned channel estimations and two-layer decoding scheme, the exact closed form expressions for uplink achievable rates are computed with and without prior knowledge, respectively. These derived expressions enable us to analyze the impacts of line-of-sight (LoS) component, two-layer decoding, data transmit power, pilot contamination, and spatially correlated Ricean fading. Then, numerical results illustrate that the system with spatially correlated Ricean fading channel is superior in terms of uplink achievable rate. Besides, it reveals that compared with the single-layer decoding, the two-layer decoding scheme can significantly improve the uplink achievable rate performance.

• 여성건강간호학회지
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• 제6권4호
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• pp.566-578
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• 2000

This study was conducted to ascertain infant's sleep and feeding patterns for the purpose of building up the positive parent-child relationship and setting up a preliminary parenting education program. The subjects were 16 infants who were cared for in their houses. The data was collected using NCASA developed by Barnard et al. from October 1st to December 3lth, 1999. The analysis of data was done with SPSSWIN for descriptive statistics and t-test, ANOVA, Correlation Analysis. The result were as follows: 1. The average day sleep of the infant was 9.51 hours, night sleep was 6.27 hours, and total sleep was 15.84 hours. The longest period of day sleep was 3.02 hours, and the longest period of night sleep was 3.72 hours. The regularity of day sleep was 34.78%, night sleep was 61.72% and total was 43.76%. 2. The frequency of daytime feeding was 5.13 times, nighttime was 2.44 times and total was 7.38 times. The regularity of feeding was 52.14%. 3. In the correlation between sleep and feeding patterns, night sleep was negatively correlated with feeding method(r=-.52, P<0.05), the longest period of day sleep was negatively correlated with feeding method(r=-.73, P<0.001), feeding frequency(r=-.60, P<0.05), the regularity of feeding(r=-.70, P<0.001). The longest period of night sleep was negatively correlated with feeding frequency (r=-.53, P<0.05). Feeding method was positively correlated with feeding frequency(r=.71, P<0.001), the regularity of feeding(r=.57, P<0.05). Day sleep was positively correlated with total sleep(r=.93, P<0.001), the regularity of total sleep was positively correlated with the longest period of day sleep(r=.54, P<0.05), total sleep(r=.65, P<0.001). The regularity of feeding was positively correlated with feeding method(r=.57, P<0.05), total feeding frequency(r=.50, P<0.05), the frequency of daytime feeding(r=.61, P<0.05). Feeding method was positively correlated with total feeding frequency(r=.71, P<0.001). In conclusion, the study showed that infants slept more in the nighttime than in the daytime, but after 3 months the pattern changed and showed that nighttime sleep was increased. Also the regularity of night sleep was increased with the infant's age. Total feeding frequency was decreased with the infant's age, and the regularity of feeding was increased in infants who slept shorter periods in the daytime than in the nighttime.

• 지역사회간호학회지
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• 제19권3호
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• pp.368-377
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• 2008

Purpose: The Purpose of this study was to investigate the effects of perceived stress on cognition in the community elderly. Methods: This was a descriptive study. Data were collected using individual-based interviews from 40 senior residents at the hall for the elderly in S City. The period of data collection was from June 19 to July 7, 2006. The tools of data collection were Mini-Mental State Examination (Folstein, Folstein, & McHugh, 1975) and Perceived Stress Scale (Cohen, Kamarck, & Mermelstein, 1983). Results: Cognition showed significant differences according to gender education, and regular exercise. Cognition was significantly correlated to stress and age. Stress was significantly correlated to orientation, recall, and attention/calculation. In the results of stepwise multiple regression, factors affecting cognition were stress, age, and gender. Conclusion: It is necessary to prepare health promotion programs that can reduce stress level in the community elderly.

• 대한치과의사협회지
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• 제54권11호
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• pp.850-864
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• 2016

The Generalized Estimating Equations (GEE) approach is a widely used statistical method for analyzing longitudinal data and clustered data in clinical studies. In dentistry, due to multiple outcomes obtained from one patient, the outcomes produced from an individual patient are correlated with one another. This study focused on the basic ideas of GEE and introduced the types of covariance matrix and working correlation matrix. The quasi-likelihood information criterion (QIC) and quasi-likelihood information criterion approximation ($QIC_u$) were used to select the best working correlation matrix and the best fitting model for the correlated outcomes. The purpose of this study is to show a detailed process for the GEE analysis using SPSS software along with an orthodontic miniscrew example, and to help understand how to use GEE analysis in dental research.

• Communications for Statistical Applications and Methods
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• 제27권3호
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• pp.301-311
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• 2020

Schwarz's Bayesian information criterion (BIC) is one of the most popular criteria for model selection, that was derived under the assumption of independent and identical distribution. For correlated data in longitudinal studies, Jones (Statistics in Medicine, 30, 3050-3056, 2011) modified the BIC to select the best linear mixed effects model based on the effective sample size where the number of parameters in covariance structure was not considered. In this paper, we propose an extended Jones' modified BIC by considering covariance parameters. We conducted simulation studies under a variety of parameter configurations for linear mixed effects models. Our simulation study indicates that our proposed BIC performs better in model selection than Schwarz's BIC and Jones' modified BIC do in most scenarios. We also illustrate an example of smoking data using a longitudinal cohort of cancer patients.

• 대한화학회지
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• 제57권3호
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• pp.370-376
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• 2013

A back propagation artificial neural network model with one hidden layer is established to correlate the liquid-liquid equilibrium data of hydrocarbon-water systems. The model has four inputs and two outputs. The network is systematically trained with 48 data points in the range of 283.15 to 405.37K. Statistical analyses show that the optimised neural network model can yield excellent agreement with experimental data(the average absolute deviations equal to 0.037% and 0.0012% for the correlated mole fractions of hydrocarbon in two coexisting liquid phases respectively). The comparison in terms of average absolute deviation between the correlated mole fractions for each binary system and literature results indicates that the artificial neural network model gives far better results. This study also shows that artificial neural network model could be developed for the phase equilibria for a family of hydrocarbon-water binaries.

• 간호행정학회지
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• 제5권1호
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• pp.39-61
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• 1999

This thesis is attempted to ananlyze the relationship between the empowerment in the nursing work environment, the job-related personal charateristics and the nursing job performance according to the individual variables of hospital, age, experience, education, position, practice area, number of nurses in the practice area, number of beds. 'Opportunity', 'support', 'informantion', ,resource' are used as structural factors of empowerment suggested by Kanter's theory of structural power in organization, and 'self-efficacy', 'burnout', 'motivation', 'organizational commitment' are defined as four job-related personal charateristics. The ultimate goal of this study is to find out the work effectiveness of the structural factors of empowerment and the job-related personal charateristics. The basic data consists of two sets of questionaires. One is the self-reporting quetionaires for the staff nurses and the other one is questionaires answered by nursing managers. The latter is designed to objectively measure the job performance. A total of 523 items of data are collected randomly from nursing population of 7 different university teaching hospitals in Seoul metropolitan area. The data were analyzed mainly using descriptive statistics, correlation analysis. ANOVA, and Duncan test according to the various purposes of the analysis. The main results of this study are as follows : 1. The mean score of four structural empowerment factors are ranked by support, opportunity, resource, and information. And among the four job-related personal charateristics self-efficacy factor shows especially high score. 2. The results of the correlation analysis between the empowerment factors and the job-related personal charateristics are as follow: 1) The 'opportunity' factor is correlated with organizational commitment' (r=.37), 'motivation' (r=.36), 'burnout' (r=-.17), and (r=.09). 2) The 'information' factor is correlated with 'organizational commitment' (r=.44), 'motivation' (r=.39), 'burnout' (r=-.24), and 'self-efficacy' (r=.17), 3) The 'support' factor is correlated with 'organizational commitment' (r=.47). 'motivation' (r=.42), 'burnout' (r=-.24), and 'self-efficacy (r=.20), 4) The 'resource' factor is correlated with 'burnout' (r=-.28), 'organizational commitment' (r=.26), and 'motivation' (r=.26), 3. The job performance are correlated with 'motivation' (r=.24) , 'self-efficacy' (r=.16), 'burnout' (r=-.16) and 'organizational commitment' (r=.12), 4. The job performance are correlated with' support' (r=.17), 'information' (r=.12) 'opportunity' (r=.10), 5. The result of ANOVA for analysing the relationship between the structural factors of empowerment and individual variables shows that the level of empowerment are significantly different by the variables such as 'hospital' and 'the number of beds in the practice area'. In summary, there were several findings in this study, First, the structural factors of empowerment defined as opportunity, support, information are significantly correalted with the job-related personal charateristics that are supposed to relate to the level of job performance. These results support the basic hypothesis suggested by Kanter's theory and implies that for improving the job performance of nurses, hospital has to have more concern about the structural factors of nursing environment.

• Journal of Community Nutrition
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• 제4권1호
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• pp.12-21
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• 2002

This study was conducted to investigate the dietary intake, anthropometric data, and association between two factors and main food sources contributing macronutrients for overweight and obese females. Subjects were 85 adult females (overweight : 28, obese 57) where mean age was 38.7y. The results are summarized as follows. Mean fat percent, BMI, obesity rate were 29.3, 23.9 and 15.1%, respectively for overweight women and 32.7, 28.3, 36.4%, respectively for obese women. There were significant differences for most of the anthropometric data between groups. Fat percent for all subjects was significantly correlated with weight, waist circumference, hip circumference, mid arm circumference or skinfold thickness for the triceps, subscapular and suprailiac (p < 0.001). The parameter which showed the highest correlation coefficient (r=0.6156) with fat Percentage was the waist to hip ratio. Any significant differences were not found in dietary intake of nutrients or in diet composition between groups. The mean energy intake was 2090.1kcal (104% of RDA) for overweight women and 2113.0kcal (106% of RDA) for obese women. PFC ratio for overweight was 17 : 24 : 59 and 18 : 23 : 58 for obese subjects, which can be regarded as higher fat and lower carbohydrate percentages compared to recommended PFC ratio (15 20 65) .4) Fat intake was positively correlated (r : 0.2301, p < 0.05) with the triceps skinfold thickness, protein intake was also positively correlated with waist circumference (r=0.2668, p < 0.05) or fat weight(r: 0.2406, p < 0.05) .5) The main food items that contributed to energy intake for overweight or obese subjects were similar (rice, pork, bread, grapes, barley) except com oil in overweight or instant noodle for obese group. The subjects in this study were taking less energy from rice and more energy from pork and bread than women from 98 National Health and Nutrition Survey. Because there were no significant differences of dietary data between overweight and obese group, further investigation considering basal metabolic rate or activity would be needed.

• 한국콘텐츠학회논문지
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• 제18권11호
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• pp.30-37
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• 2018

인터넷 시대를 살아가는 현대인의 식품 소비는 다양한 대충 매체 및 소셜 미디어를 통해 신속하고 방대한 정보 전달에 영향을 받는 것으로 알려져 있다. 2018년 4월 국내 언론 보도에 따르면, 양파 재배 면적이 증가하고 양파 생산량이 증가할 것으로 예상되며, 이후에 양파 가격은 폭락할 것으로 예상되었다. 이러한 상황을 고려하여 SNS, 인터넷 정보 검색, 방송 프로그램에서 언급된 양파 관련 정보를 분석하여, 실제 가격폭락이 발생하기 전에, 양파 소비를 촉진할 수 있는 요인을 파악할 필요가 있다. 2018년 양파 생산량 증가에 따른 양파 가격 폭락이 예상되는 상황에, 가장 최근 양파 생산량 증가에 따라 가격 폭락을 경험하였던 2014년의 방송 프로그램 및 SNS가 양파 소비와 연계되었는지 파악하고자, 양파 소비 촉진과 관련된 정형 및 비정형 빅데이터를 수집하여, 양파 소비 촉진과 관련된 변수를 찾아 양파 가격 하락이 예상되는 2018년에 소비 촉진에 활용하고자 본 연구를 수행하였다. 연구 결과, 방송 뉴스의 양파 언급 기사 수(3~6주), 양파와 건강을 언급하는 방송 프로그램 수(11주), 양파의 효능을 언급하는 블로그의 댓글 빈도(5주)가 양파 구매금액 증가에 시차를 두고 양의 상관관계를 갖는 것을 확인한 본 연구 결과를 근거로, 양파 생산량 증가에 따른 양파 가격 폭락 시, 양파 소비 촉진을 위한 홍보에, 뉴스, 먹방, 쿡방 등의 방송 프로그램 및 블로그 등의 매체를 활용하는 소비촉진에 기여할 것으로 여겨진다.