• The Korean journal of sports medicine
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• v.36 no.4
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• pp.207-213
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• 2018

Purpose : The aim of this study was to investigate the effects of foot position on dynamic stability in female with genu varum. M ethods: Eight females with genu varum participated in this study and performed the four squat exercise methods that foot position ($-45^{\circ}$, $0^{\circ}$, $+45^{\circ}$) and $0^{\circ}$ squat with band. Center of pressure (COP; anterior-posterior, medial-lateral, traveled distance, ellipse area) and ground reaction force as dynamic stability were measured using footscan system. Multivariate analysis of variance and one-way repeated analysis of variance measurement with Tukey honestly significant difference were used to identify significant differences of foot angle ($-45^{\circ}$, $0^{\circ}$, $+45^{\circ}$) and $0^{\circ}$ squat with band method. Results: In anterior-posterior COP displacement, $-45^{\circ}$ foot angle and $0^{\circ}$ squat with band were significantly showed lower than $+45^{\circ}$ foot angle squat (p=0.006). Also, in COP traveled distance, $0^{\circ}$ squat was significantly showed lower than $+45^{\circ}$ foot angle (p=0.019). During the descending phase, ground reaction force significantly showed in -45 foot angle was lower than other exercise methods. Conclusion: The $0^{\circ}$ squat with band exercise showed higher dynamic stability and $+45^{\circ}$ foot angle squat exercise showed lower dynamic stability in female with genu varum.

• Asia-Pacific Journal of Business
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• v.11 no.4
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• pp.255-269
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• 2020

Purpose - This paper analyzes the market efficiency focusing on the long memory properties of the domestic futures market. By decomposing futures prices into yield and volatility and looking at the long memory properties of the time series, this study aims to understand the futures market pricing and change behavior and risks, specifically and in detail. Design/methodology/approach - This study analyzes KOSPI 200 futures, KOSDAQ 150 futures, 3 and 10-year government bond futures, US dollar futures, yen futures, and euro futures, which are among the most actively traded on the Korea Exchange. To analyze the long memory and market efficiency, we used the Variance Ratio, Rescaled-Range(R/S), Geweke and Porter-Hudak(GPH) tests as semi- parametric methods, and ARFIMA-FIGARCH model as the parametric method. Findings - It was found that all seven futures supported the efficiency market hypothesis because the property of long memory turned out not to exist in their yield curves. On the other hand, in futures volatility, all 7 futures showed long memory properties in the analysis, which means that if new information is generated in the domestic futures market and the market volatility once expanded due to the impact, it does not decrease or shrink for a long period of time, but continues to affect the volatility. Research implications or Originality - The results of this paper suggest that it can be useful information for predicting changes and risks of volatility in the domestic futures market. In particular, it was found that the long memory properties would be further strengthened in the currency futures and bond rate futures markets after the global financial crisis if the regime changes of the domestic financial market are taken into account in the analysis.

• Asia-Pacific Journal of Business
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• v.13 no.3
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• pp.183-208
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• 2022

Purpose - The main purpose of this study is to widely investigate the impact of recent pandemic crises on the synchronization of the world capital markets through 25 stock indices from major developed countries. Design/methodology/approach - This study collects 25 stock indices from major developed countries and the time period is between January 5, 2001 and February 24, 2022. The data sets used in the study include finance.yahoo.com and Investing.com.. The Granger causality analysis, unit-root test, VAR analysis, and forecasting error variance decomposition were hired in order to analyze the data. Findings - First, there are significant inter-relations among 25 countries around recent major pandemic crises(such as SARS, A(H1N1), MERS, and COVID19), which is consistent result with previous literature. Second, COVID19 shows much stronger impact on the world-wide synchronization than other pandemics. Third, the return volatility of each stock market varies, unit root tests show that daily stock index data are unstable while daily stock index returns are stable, and VAR(Vector Auto Regression) analyses presents significant inter-relations among 25 capital markets. Fourth, from the impulse response function analyses, we find that each market affects the other markets for short term periods, about 2~4 days, and no long term effect was not found. Fifth, Granger causality tests show one-side or two-sides synchronization between capital markets and we estimate, through forecasting error variance decomposition method, that the explanatory portions of each capital market on other markets vary from 10 to 80%. Research implications or Originality - The above results all together show that pandemic crises have strong effects on the synchronization of world capital markets and imply that these synchronizations should be carefully considered both in the investment decisions by individual investors and in the financial and economic policies by governments.

• The Korean Journal of Applied Statistics
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• v.35 no.5
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• pp.579-591
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• 2022

Functional data is collected in various fields. It is often necessary to test whether there are differences among groups of functional data. In this case, it is not appropriate to explain using the point-wise ANOVA method, and we should present not the point-wise result but the integrated result. Various studies on functional data analysis of variance have been proposed, and recently implemented those methods in the package fdANOVA of R. In this paper, I first explain ANOVA and multivariate ANOVA, then I will introduce various methods of analysis of variance for univariate and multivariate functional data recently proposed. I also describe how to use the R package fdANOVA. This package is used to test equality of weekly temperatures in Seoul and Busan through univariate functional data ANOVA, and to test equality of multivariate functional data corresponding to handwritten images using multivariate function data ANOVA.

• Women's Health Nursing
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• v.28 no.4
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• pp.338-347
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• 2022

Purpose: The incidence of high-risk pregnancies is increasing in Korea as the birth age increases due to late marriage. Maternal-fetal attachment is an important factor that affects children even after childbirth, but it is difficult for high-risk pregnant women to form maternal-fetal attachment. The current study aimed to explore whether taegyo practice (i.e., pregnant women's efforts for fetal good growth and development), self-esteem, and social support influenced the degree of maternal-fetal attachment in women with high-risk pregnancies. Methods: The participants included 226 pregnant Korean women at ≥20 gestational weeks, hospitalized with 15 high-risk pregnancy conditions as defined by the Ministry of Health and Welfare. Recruitment via convenience sampling was done at four sites in Busan, Korea. Surveys were distributed and collected from February 1 to 28, 2022. Data analysis was conducted using descriptive statistics, the t-test, one-factor analysis of variance, Pearson correlation coefficients, and hierarchical multiple regression. Results: On average, participants were 33.97±4.23 years of age and at 31.65±6.23 gestational weeks. Preterm labor (35.4%) and gestational diabetes (21.0%) were the most common high-risk conditions. Maternal-fetal attachment was positively correlated with taegyo practice (r=.70, p<.001), self-esteem (r=.53, p<.001), and social support (r=.53, p<.001), all with statistical significance. Taegyo practice (β=.50, p<.001) and social support (β=.17, p=.030) explained 53% of variance in maternal-fetal attachment in women with high-risk pregnancies. Conclusion: Nurses caring for women with high-risk pregnancies during hospitalization can use these findings by promoting taegyo practice and enhancing social support to increase maternal-fetal attachment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.165-172
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• 2017

Machines are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. Under the process mean shift, production cost, failure cost and quality loss function cost are increasing continuously. Therefore a periodic preventive resetting the process is necessary. We suppose that the wear level is observable. In this case, process mean shift problem has similar characteristics to the maintenance policy model. In the previous studies, process mean shift problem has been studied in several fields such as 'Tool wear limit', 'Canning Process' and 'Quality Loss Function' separately or partially integrated form. This paper proposes an integrated cost model which involves production cost by the material, failure cost by the nonconforming items, quality loss function cost by the deviation between the quality characteristics from the target value and resetting the process cost. We expand this process mean shift problem a little more by dealing the process variance as a function, not a constant value. We suggested a multiplier function model to the process variance according to the analysis result with practical data. We adopted two-side specification to our model. The initial process mean is generally set somewhat above the lower specification. The objective function is total integrated costs per unit wear and independent variables are wear limit and initial setting process mean. The optimum is derived from numerical analysis because the integral form of the objective function is not possible. A numerical example is presented.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.3
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• pp.293-298
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• 2015

The vessel encounter data collected from the vessel trajectories in the maritime traffic situation is possible to analyze vessel collision and near-collision risk using statistical method. In this study, analyzing variables extracted from the vessel encounter data using factor analysis, we determine main factors effecting vessel collision risk from vessel encounter data. In order to calculate each factor, it used principal component analysis for factor analysis after normalization and standardization of vessel encounter variables. As a result of the factor analysis, main effect factors are summarized into the vessel approach factor and collision avoidance variance factor.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.89-94
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• 1987

The fluctuations of sea surface temperatures (SST) and their anomalies in the Tsushima Current region are studied by means of empirical orthogonal function (EOF) analysis of the monthly SST data for 30 years (1941-1970) at 8 coastal stations. The overall features of the seasonal variation of SST are described by the first EOF mode, which explains $97.2\%$ of the total variance. Annual ranges of seasonal variation of SST and root-mean-square amplitudes of SST anomalies in the downstream of the Tsushima Current are larger than those in the upstream. The SST anomalies in the Tsushima Current region consist of simultaneous fluctuations, which explain $40.9\%$ of the total variance, and 'see-saw' fluctuations of which rise and fall in the upstream are opposite to those in the downstream. The latter second EOF mode explains $19.3\%$ of the total variance. We generated the low-pass (periods longer than 24 months), band-pass (periods between 6 and 24 months) and high-pass (periods shorter than 6 months) SST anomaly series and analyzed them by EOF method. The spatial distributions of the first and second EOF modes of all filtered SST anomalies are similar to each other.

• Journal of the Speleological Society of Korea
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• v.14 no.15
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• pp.42-90
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• 1987

Lee, Moon Won reported by 63 kinds lescribing the petrography and bulk chemical Composition in Petrology of Cheju volcanic island. The total Chemical Composition data was analyzed by the program of FORTRAN77. First, the Conversition equations and the scatter diagram were examined to the analysis, by the least square method. Next, a statistical data requested a mean Value, maximum value, minimum value, the range, the standard deviation, the variance, the Standord Error and the Coefficient of variation. In the standard deviation, a small Composition is MnO and P$_2$O$\sub$5/, a large Composition is SiO$_2$, Mgo and FeO. The Standard error and the variance were the tandency looked like the Standard deviation well. However, the Coefficient Variation differs from the Standard deviation. Where, a large Coefficient of variation are H$_2$O$\^$-/ and H$_2$O$\^$+/, a small Coefficient of variation are Al$_2$O$_3$ and SiO$_2$. The Correlation of Coefficient Can be Calculated numerically from the relation between SiO$_2$, Al$_2$O$_3$ and TiO$_2$ to other Compositions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.135-141
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• 2024

Despite the innovative technological advances in the aviation industry, hard landing events that occur during aircraft landing account for 13% of all accidents. Hard landing when landing an aircraft affects normal operation by generating a large load on the landing gear and the fuselage. In order to identify these risk factors, the airline monitors the high vertical acceleration event, a precursor to hard landing, through QAR (Quick Access Recorder) flight data analysis, and prepares and implements mitigation measures. In this study, it is intended to contribute to safety management based on flight data analysis that identifies the characteristics of high vertical acceleration G event data that can cause such hard landing and detailed parameters of precursor signs, and to identify the causal relationship of the occurrence of the event by applying statistical analysis methods such as variance analysis, correlation analysis, and regression analysis models to identify the characteristics of the event occurrence and eliminate the cause in advance.