• Journal of Distribution Science
• /
• v.13 no.9
• /
• pp.103-112
• /
• 2015

Purpose - This paper aims to provide a step-by-step approach to factor analytic procedures, such as principal component analysis (PCA) and exploratory factor analysis (EFA), and to offer a guideline for factor analysis. Authors have argued that the results of PCA and EFA are substantially similar. Additionally, they assert that PCA is a more appropriate technique for factor analysis because PCA produces easily interpreted results that are likely to be the basis of better decisions. For these reasons, many researchers have used PCA as a technique instead of EFA. However, these techniques are clearly different. PCA should be used for data reduction. On the other hand, EFA has been tailored to identify any underlying factor structure, a set of measured variables that cause the manifest variables to covary. Thus, it is needed for a guideline and for procedures to use in factor analysis. To date, however, these two techniques have been indiscriminately misused. Research design, data, and methodology - This research conducted a literature review. For this, we summarized the meaningful and consistent arguments and drew up guidelines and suggested procedures for rigorous EFA. Results - PCA can be used instead of common factor analysis when all measured variables have high communality. However, common factor analysis is recommended for EFA. First, researchers should evaluate the sample size and check for sampling adequacy before conducting factor analysis. If these conditions are not satisfied, then the next steps cannot be followed. Sample size must be at least 100 with communality above 0.5 and a minimum subject to item ratio of at least 5:1, with a minimum of five items in EFA. Next, Bartlett's sphericity test and the Kaiser-Mayer-Olkin (KMO) measure should be assessed for sampling adequacy. The chi-square value for Bartlett's test should be significant. In addition, a KMO of more than 0.8 is recommended. The next step is to conduct a factor analysis. The analysis is composed of three stages. The first stage determines a rotation technique. Generally, ML or PAF will suggest to researchers the best results. Selection of one of the two techniques heavily hinges on data normality. ML requires normally distributed data; on the other hand, PAF does not. The second step is associated with determining the number of factors to retain in the EFA. The best way to determine the number of factors to retain is to apply three methods including eigenvalues greater than 1.0, the scree plot test, and the variance extracted. The last step is to select one of two rotation methods: orthogonal or oblique. If the research suggests some variables that are correlated to each other, then the oblique method should be selected for factor rotation because the method assumes all factors are correlated in the research. If not, the orthogonal method is possible for factor rotation. Conclusions - Recommendations are offered for the best factor analytic practice for empirical research.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.546-559
• /
• 2016

This study was conducted to analyze the relationship between sleep quality, stress response, physical activity and sleep hygiene in shift work nurses and identify factors influencing sleep quality. The participants were 168 shift nurses from university hospitals and general hospitals located in C city, Gyeongnam. Data were collected from March 25 to 31, 2016. The study instrument use to the Pittsburgh Sleep Quality Index, Stress Response Inventory, Korean version of the International Physical Activity Questionnaire Short Form and Sleep Hygiene Scale. Date were analyzed by frequency, t-test, ANOVA, Pearson's correlation and hierarchical multiple regression using SPSS/win18.0. The sleep quality index was 7.35 (range 0-21), stress response was 2.20 (range 1-5), physical activity was 3986MET-min/week, and sleep hygiene was 2.73 (range 1-6 points). There were significant differences in sleep quality according to shift work experience, health status and circadian rhythm type. Factors influencing sleep quality included shift work experience, sleep hygiene, stress response and physical activity, which together explained 40% of the total variance of sleep quality. Therefore, it is recommended that sleep hygiene education be implemented as a strategy to reduce stress response, and that shift work nurses engage in a moderate level of physical activity to improve their sleep quality.

• Proceedings of the Korea Database Society Conference
• /
• 1999.06a
• /
• pp.175-186
• /
• 1999

Detecting the features of significant patterns from their own historical data is so much crucial to good performance specially in time-series forecasting. Recently, a new data filtering method (or multi-scale decomposition) such as wavelet analysis is considered more useful for handling the time-series that contain strong quasi-cyclical components than other methods. The reason is that wavelet analysis theoretically makes much better local information according to different time intervals from the filtered data. Wavelets can process information effectively at different scales. This implies inherent support fer multiresolution analysis, which correlates with time series that exhibit self-similar behavior across different time scales. The specific local properties of wavelets can for example be particularly useful to describe signals with sharp spiky, discontinuous or fractal structure in financial markets based on chaos theory and also allows the removal of noise-dependent high frequencies, while conserving the signal bearing high frequency terms of the signal. To date, the existing studies related to wavelet analysis are increasingly being applied to many different fields. In this study, we focus on several wavelet thresholding criteria or techniques to support multi-signal decomposition methods for financial time series forecasting and apply to forecast Korean Won / U.S. Dollar currency market as a case study. One of the most important problems that has to be solved with the application of the filtering is the correct choice of the filter types and the filter parameters. If the threshold is too small or too large then the wavelet shrinkage estimator will tend to overfit or underfit the data. It is often selected arbitrarily or by adopting a certain theoretical or statistical criteria. Recently, new and versatile techniques have been introduced related to that problem. Our study is to analyze thresholding or filtering methods based on wavelet analysis that use multi-signal decomposition algorithms within the neural network architectures specially in complex financial markets. Secondly, through the comparison with different filtering techniques' results we introduce the present different filtering criteria of wavelet analysis to support the neural network learning optimization and analyze the critical issues related to the optimal filter design problems in wavelet analysis. That is, those issues include finding the optimal filter parameter to extract significant input features for the forecasting model. Finally, from existing theory or experimental viewpoint concerning the criteria of wavelets thresholding parameters we propose the design of the optimal wavelet for representing a given signal useful in forecasting models, specially a well known neural network models.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.5
• /
• pp.527-534
• /
• 2020

A significant factor in construction work is cost. At early- and advanced-stage design, costs should be calculated to derive realistic cost estimates according to unit price calculation. Based on these estimates, the economic feasibility of construction work is assessed, and whether to proceed is determined. Through the Korea Institute of Civil Engineering and Building Technology, the construction cost index has been calculated by indirect methods after both the producer price index and construction market labor have been reprocessed to easily adjust the price changes of construction costs in Korea, and the Institute has announced it since 2004. As of January 2000, however, the construction cost index was released, and this has a time constraint on the correction and use of past construction cost data to the present moment. Variables were calculated to compute a rough construction cost that utilized past construction costs through surveys of the producer price index and the construction market labor force consisting of the construction cost index. After significant independent variables among the many variables were selected through correlation analysis, the construction cost index from 1970 to 1999 was calculated and presented through multiple regression analysis. This study therefore has prominent significance in terms of proposing a method of calculating rough construction costs that utilize construction costs that pre-date the 2000s.

• Journal of Korean Society of Transportation
• /
• v.25 no.6
• /
• pp.197-208
• /
• 2007

Enormously sized buildings are appearing world-wide with the advancement of construction techniques. Large-scaled and complicated structures will have increased difficulties for dealing with safety, and will demand well-matched safety measures. This research introduced up-to-date techniques and systems which are applied in buildings in foreign nations. Furthermore, it proposed s direct guidance plan for buildings in case of fire. Since it is possible to install wireless sensor networks which detect fires or effects of fire, the plan makes use of this information. Accordingly, the authors completed a direct guidance plan that was based on omnidirectional guidance lights. It is possible to select a route with concern about both time and capacity with a concept of a non-dominated path. Finally, case studies showed that quickest path algorithms were effective for guiding efficient dispersion routes and in case of restriction of certain links in preferred paths due to temperature and smoke, it was possible to avoid relevant links and to restrict demand in the network application. Consequently, the algorithms were able to maximize safety and minimize evacuation time, which were the purposes of this study.

• Korean Journal of Medicinal Crop Science
• /
• v.6 no.2
• /
• pp.121-125
• /
• 1998

This experiment was carried out to investigate the effects of direct seeding and planting of seedlings in different ages on yield and yield characteristics of Cynanchum wilfordii $H_{EMSLY}$. Emergence date was three days earlier in direct seeding compared to May 14 in plots planted with one - or three - year - old seedlings. Petiole length was 16cm and 26cm longer in direct seeding and 1 - year - old seedlings, respectively, compared to 279cm in plot of 3 - year - old seedling. Root diameter was 0.4cm thicker in direct seeding and 0.5cm thicker in 1 - year - old seedlings compared to 1.0cm in seedlings of three years old. Root length was 7.2cm shorter in direct seeding, but was 0.6cm longer in 1 - year - old seedlings than 32.2cm in seedlings of three years old. Yield increased by 29 % in direct seeding and 55% in seedlings of one year old compared to 1,403kg/l0a in 3 - year - old seedlings. In cultivation of Cynanchum wilfordii $H_{EMSLY}$, the suitable planting methods were direct seeding or the use of 1 - year - old seedlings which were profitable at higher density as $50{\times}10cm$.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.5
• /
• pp.525-529
• /
• 2009

Cytolethal distending toxins (CDTs) represent an emerging family of newly described bacterial products that are produced by a number of pathogens. The genes encoding these toxins have been identified as a cluster of three adjacent genes, cdtA, cdtB, and cdtC, plus 5 cdt genetic variants, designated as cdt-I, cdt-II, cdt-III, cdt-IV, and cdt-V, have been identified to date. In this study, a general multiplex PCR system designed to detect Escherichia coli cdts was applied to investigate the presence of cdt genes among isolates. As a result, among 366 E. coli strains, 2.7% were found to carry the cdtB gene. In addition, the use of type-specific primers revealed the presence of cdt-I, cdtIV, and cdt-V types of the cdt gene, yet no cdt-II or cdt-III strains. The presence of other virulence genes (stxl, stx2, eae, bfp, espA, espB, and espD) was also investigated using a PCR assay. Among the 10 cdtB gene-positive strains, 8 were identified as COT-producing typical enteropathogenic E. coli (EPEC) strains ($eae^+$, $bfp^+$), whereas 2 were identified as CDT-producing atypical EPEC strains ($eae^+$, $bfp^-$). When comparing the cytotoxic activity of the CDT-producing typical and atypical EPEC strains, the CDT-producing atypical EPEC strains appeared to be less toxic than the CDT-producing typical EPEC strains.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.8
• /
• pp.260-267
• /
• 2018

Surface electromyography (sEMG) is mainly used as an on/off switch in the early stage of the study and was then expanded to navigational control of powered-wheelchairs and recognition of sign language or finger gestures. There are difficulties in communication between people who know and do not know sign language; therefore, many efforts have been made to recognize sign language or finger gestures. Recently, use of sEMG signals to recognize sign language signals have been investigated; however, most studies of this topic conducted to date have focused on Chinese finger number gestures. Since sign language and finger gestures vary among regions, Korean- and Chinese-finger number gestures differ from each other. Accordingly, the recognition performance of Korean finger number gestures based on sEMG signals can be severely degraded if the same muscles are specified as for Chinese finger number gestures. However, few studies of Korean finger number gestures based on sEMG signals have been conducted. Thus, this study was conducted to identify potential forearm muscles from which to collect sEMG signals for Korean finger number gestures. To accomplish this, six Korean finger number gestures from number zero to five were investigated to determine the usefulness of the proposed muscles and electrode placements by showing that CNN technique based on sEMG signal after sufficient learning recognizes six Korean finger number gestures in accuracy of 100%.

• Journal of Gastric Cancer
• /
• v.6 no.3
• /
• pp.139-145
• /
• 2006

Purpose: Although several chemotherapy regimens used against advanced gastric cancer (AGC) have been studied extensively in an attempt to further improve the prognosis of patients, to date, no standard chemo-therapeutic regimens have been established. The aim of this study was to determine the anti-tumor efficacy and safety of TS-1 or TS-1 plus cisplatin (CDDP). Material and Methods: We treated 78 patients with AGC either with $80\;mg/m^{2}$ of TS-1 for 28 days, which was followed by a 2-week rest, or with $80\;mg/m^{2}$ of TS-1 for 21 days and $80\;mg/m^{2}$ of CDDP on day 8 every 5 weeks. Results: Tumor response rates in the neoadjuvant chemotherapy group and in the recurrent or post-palliative surgery group were 87.5% and 32.4%, respectively, and they were 28.6% and 48.4%, respectively, in the TS-1 group and the TS-1 plus CDDP group. The survival rates in the recurrent and the post-palliative surgery group were significantly different according to the degree of tumor response (P=0.0016), but the one-year survival rates according to the kinds of regimens (TS-1 or TS-1/CDDP group) were not significantly different. The incidences of grade 3 or 4 adverse effects in the TS-1 and the TS-1/CDDP groups were 14.3% and 36.8%, respectively. Conclusion: The anti-tumor efficacy and safety of TS-1 and TS-1 plus CDDP in Korean patients with AGC seemed to be high with modest adverse effects, thus suggesting the possible use of this regimen as a standard chemotherapy for gastric cancer.

• Atmosphere
• /
• v.24 no.1
• /
• pp.123-130
• /
• 2014

The automated prediction system for seasonal tropical cyclone (TC) activity is established at the National Typhoon Center of the Korea Meteorological Administration (KMA) to provide effective operation and control of the system for user who lacks knowledge of the system. For automation of the system, two procedures which include subjective decisions by user are performed in advance, and their output data are provided as input data. To provide the capability to understand the operational processes for operational user, the input and output data are summarized with each process, and the directory structure is reconstructed following KMA's standard. We introduce a user interface using namelist input parameters to effectively control operational conditions which is fixed or should be manually set in the previous version of the prediction system. To operationally use early prediction which become available through the automation, its performances are evaluated according to initial condition dates. As a result, high correlations between the observed and predicted TC counts are kept for all track clusters even though advancing the initial condition date from May to January.