• Journal of Digital Convergence
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• v.11 no.10
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• pp.17-29
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• 2013

The major aim of this research is to examine the effect of computer and internet literacy and cellular phone possession on depression and suicidal ideation among elderly. This study used data of 2011 national survey results on the elderly life conditions. To determine the effectiveness of computer and internet literacy and cellular phone possession, a total of 6,774 respondents over 60 years of age was selected. The SPSS package was used to analyze the data. Multiple linear regression and logit analysis was run to verify influence of information conditions(computer and internet literacy and cellular phone possession) on depression and suicidal ideation. The results are as follows. First, the elder who is male, younger, has higher education and economic level and lives with spouce is in good information conditions. On the contrary to this, the elder who is female, older, low level of education and economic, single and lives with grandchildren is in information minority group. They have high level of depression and rate of suicidal ideation. Second, computer and internet literacy and cellular phone possession associate with level of depression significantly. Third, computer and internet literacy do not associate with suicidal ideation significantly. The results of this study provide significant source to plan informatization policy and welfare services for socially isolated older people.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.62-73
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• 2020

Access management is aimed at preserving the road's high intercity mobility. In urbanized areas, immoderate acceleration lane-length requirements restrict the accessibility of land. Therefore, there are many opinions to revise the minimum acceleration lane-length requirement. For this purpose, it is important to diagnose the effects of slow vehicles on the mainline. This study analyzed a single merging vehicle's total delay occurrence depending on the mainline traffic flow rate and merging speed. A linear relationship was observed between the mainline traffic flow rate and total delay. As a merging speed increases gradually from 40km/h to 100km/h in 20km/h intervals, the total delay decreases by 5.0, 1.6, and 5.1 times, respectively. This shows that the ideal condition with the total delay is less than 0.5 vehicle·sec when there is no speed difference between the mainline and merging vehicle. On the other hand, given the one-second response time of drivers, the total delay occurrence was slightly low when the speed difference between the mainline and merging vehicle was less than 20km/h.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.961-967
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• 2019

This research presents an efficient method based on computational fluid dynamics (CFD) for estimating the resistance performance of a ship with a large settlement amount and a dynamic trim. The settlement of the inviscid flow analysis and the results of dynamic trim were used to set a large attitude for the ship prior to performing a viscous flow analysis; a viscous flow analysis was subsequently performed by Dynamic Fluid Body Interaction (DFBI). This method is termed as method I, in which a simple grating system can be used without employing the overset mesh technique by setting many attitudes before interpretation. Thus, method I is advantageous in reducing calculation time and improving calculation accuracy. The viscous flow analysis was performed using a commercial CFD code STAR-CCM+. Compared with the final convergence result, the first viscous flow analysis result of method I exhibited a variation of less than 1 % of resistance. The result was obtained by changing the gratings each time an attitude is changed at each calculation stage, based on the DFBI method provided to STAR-CCM+ using a simple grating system, which is not a superposed grating. This method is termed as method II. Compared with method II of resistance, method I exhibited a dif erence of 0.03-0.6 % for linear velocity. The results of method I were confirmed to be qualitatively and quantitatively appropriate through comparison with several trillion simulations.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.6
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• pp.747-752
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• 2006

In this paper, the adaptive fuzzy sliding mode controller with two systems is designed. The existing sliding mode controller used to $approximation{\^{u}}(t)$ with discrete sgn function and sat function for keeping the state trajectories on the sliding surface[1]. The proposed controller decrease the disturbance for uncertain control gain and This paper is concerned with an Adaptive Fuzzy Sliding Mode Control(AFSMC) that the fuzzy systems ate used to approximate the unknown functions of nonlinear system. In the adaptive fuzzy system, we adopt the adaptive law to approximate the dynamics of the nonlinear plant and to adjust the parameters of AFSMC. The stability of the suggested control system is proved via Lyapunov stability theorem, and convergence and robustness properties ate demonstrated. Futhermore, fuzzy tuning improve tracking abilities by changing some sliding conditions. In the traditional sliding mode control, ${\eta}$ is a positive constant. The increase of ${\eta}$ has led to a significant decrease in the rise time. However, this has resulted in higher overshoot. Therefore the proposed ${\eta}$ tuning AFSMC improve the performances, so that the controller can track the trajectories faster and more exactly than ordinary controller. The simulation results demonstrate that the performance is improved and the system also exhibits stability.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.591-598
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• 2021

The digital phase-locked loops(DPLL) is a circuit used for phase synchronization and has been generally used in various fields such as communication and circuit fields. State estimators are used to design digital phase-locked loops, and infinite impulse response state estimators such as the well-known Kalman filter have been used. In general, the performance of the infinite impulse response state estimator-based digital phase-locked loop is excellent, but a sudden performance degradation may occur in unexpected situations such as inaccuracy of initial value, model error, and disturbance. In this paper, we propose a minimum variance finite impulse response filter with optimal horizon for designing a new digital phase-locked loop. A numerical method is introduced to obtain the measured value interval length, which is an important parameter of the proposed finite impulse response filter, and to obtain a gain, the covariance matrix of the error is set as a cost function, and a linear matrix inequality is used to minimize it. In order to verify the superiority and robustness of the proposed digital phase-locked loop, a simulation was performed for comparison and analysis with the existing method in a situation where noise information was inaccurate.

• The Journal of the Convergence on Culture Technology
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• v.7 no.2
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• pp.107-116
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• 2021

Purpose : To examine the relationship among osteoporosis knowledge, osteoporosis preventive behaviors, self-efficacy and health-related quality of life of middle aged women and to find out factors which influence health-related quality of life. Methods : For study subjects, female patients aged 40 to 64 and hospitalized at the surgical wards of two general hospitals in G city were conveniently sampled. The data have been collected from January 11 to March 10, 2018. Data were analyzed by descriptive statistics, t-test, ANOVA, Scheffe's test, Pearson's correlation coefficient, and multiple regression. Results : The average score of osteoporosis knowledge was 12.50±3.47, the average score of osteoporosis preventive behaviors was 44.96±8.16 and the average score of osteoporosis self-efficacy was 40.38±8.07. The factors influencing EQ-5D Index in health-related quality of life were comorbidity, osteoporosis preventive behaviors, osteoporosis knowledge and average monthly income, which could account for health-related quality of life at 18.0%. The factors influencing EQ-5D VAS were osteoporosis preventive behaviors, self-efficacy, osteoporosis knowledge and age of menarche, which could account for health-related : Higher osteoporosis knowledge, osteoporosis preventive behaviors and self-efficacy, the better the subjects health-related quality of life. Therefore, as a way to promote health-related quality of life of middle aged women, the constant development and the application of a program which may promote osteoporosis knowledge, osteoporosis preventive behaviors and self-efficacy are needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.598-603
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• 2019

Three-dimensional shape measurement technology is used in various industries. Among them, optical three-dimensional shape measurement techniques based on the optical trigonometry are mainly used in the field of semiconductor product inspection, where large quantities of three-dimensional shape measurements are made daily in factories and fine measurements are also required. The light source and the drive circuit, which are components of three-dimensional measurement equipment based on this optical trigonometry, produce heat generated by prolonged operation, and may be exposed to conditions where the ambient temperature is not constant, resulting in temperature-induced measurement errors. In this study, the compensation method of the Thermal Errors for Phase Measuring Profilometry is proposed. Three-Dimensional Shape Measurement Equipment based on Phase Measuring Profilometry is implemented to measure the height of an object and ambient temperature for 10 Hours, and a regression line was obtained line by making simple linear regression using measured temperature and height values. This regression line was used to correct the error of the height measurement according to the temperature, and thermal error was from 139.88 um(Micrometer) to 13.12 um.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.453-463
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• 2019

The purpose of this study was to investigate one-person household its health-related quality of life(HRQOL) using data from the seventh Korea national health and nutrition examination survey(KNHANES Ⅶ-2) 2017. The subjects were 301. The data were analyzed by frequency, descriptive analysis and linear regression analysis using SPSS complex samples Win 25 program. The HRQOL score was 0.92, and 2.5% of the subjects in the pain and discomfort area had severe problems. HRQOL related to the subject was 0.034, 0.039, and 0.031, respectively, when the household income level was lower, the education level was lower than elementary school graduates, and if they did not drink at present. HRQOL was 0.072, 0.065, 0.103, and 0.040 in perceived health status good or moderate, the absence of activity limitation and arthritis, was explained 43.1%. There is a need to develop interdisciplinary approaches with great interest in improving the one-person households HRQOL.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.135-145
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• 2019

Prolonged recession has caused the youth unemployment rate in Korea to remain at a high level of approximately 10% for years. Recently, the number of unemployed Koreans in their 30s and 40s has shown an upward trend. To expand the government's employment promotion and unemployment benefits from youth-centered policies to diverse age groups, including people in their 30s and 40s, prediction models for different age groups are required. Thus, we aimed to develop unemployment prediction models for specific age groups (30s and 40s) using available unemployment rates provided by Statistics Korea and Google search queries related to them. We first estimated multiple linear regressions (Model 1) using seasonal autoregressive integrated moving average approach with relevant unemployment rates. Then, we introduced Google search queries to obtain improved models (Model 2). For both groups, consequently, Model 2 additionally using web queries outperformed Model 1 during training and predictive periods. This result indicates that a web search query is still significant to improve the unemployment predictive models for Koreans. For practical application, this study needs to be furthered but will contribute to obtaining age-wise unemployment predictions.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.239-247
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• 2019

An accurate prediction of emotion is a very important issue for the sake of patient-centered medical device development and emotion-related psychology fields. Although there have been many studies on emotion prediction, no studies have applied the heart rate variability and neuro-fuzzy approach to emotion prediction. We propose ANFEP(Adaptive Neuro Fuzzy System for Emotion Prediction) HRV. The ANFEP bases its core functions on an ANFIS(Adaptive Neuro-Fuzzy Inference System) which integrates neural networks with fuzzy systems as a vehicle for training predictive models. To prove the proposed model, 50 participants were invited to join the experiment and Heart rate variability was obtained and used to input the ANFEP model. The ANFEP model with STDRR and RMSSD as inputs and two membership functions per input variable showed the best results. The result out of applying the ANFEP to the HRV metrics proved to be significantly robust when compared with benchmarking methods like linear regression, support vector regression, neural network, and random forest. The results show that reliable prediction of emotion is possible with less input and it is necessary to develop a more accurate and reliable emotion recognition system.