• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.5860-5876
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• 2018

A single snapshot data can only provide limited amount of information so that the rank of covariance matrix is not full, which is not adopted to complete the parameter estimation directly using the traditional super-resolution method. Aiming at solving the problem, a joint time delay and angle estimation using matrix pencil method based on information reconstruction vector for orthogonal frequency division multiplexing (OFDM) signal is proposed. Firstly, according to the channel frequency response vector of each array element, the algorithm reconstructs the vector data with delay and angle parameter information from both frequency and space dimensions. Then the enhanced data matrix for the extended array element is constructed, and the parameter vector of time delay and angle is estimated by the two-dimensional matrix pencil (2D MP) algorithm. Finally, the joint estimation of two-dimensional parameters is accomplished by the parameter pairing. The algorithm does not need a pseudo-spectral peak search, and the location of the target can be determined only by a single receiver, which can reduce the overhead of the positioning system. The theoretical analysis and simulation results show that the estimation accuracy of the proposed method in a single snapshot and low signal-to-noise ratio environment is much higher than that of Root Multiple Signal Classification algorithm (Root-MUSIC), and this method also achieves the higher estimation performance and efficiency with lower complexity cost compared to the one-dimensional matrix pencil algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.4
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• pp.495-502
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• 2022

Web crawler, which is mainly used to collect text on the web today, is difficult to maintain and expand because researchers must implement different collection logic by collection channel after analyzing tags and styles of HTML documents. To solve this problem, the web crawler should be able to collect text by formalizing HTML documents to the same structure. In this paper, we designed and implemented WCTT(Web Crawling system based on Tag path and Text appearance frequency), a web crawling system that collects text with a single collection logic by formalizing HTML documents based on tag path and text appearance frequency. Because WCTT collects texts with the same logic for all collection channels, it is easy to maintain and expand the collection channel. In addition, it provides the preprocessing function that removes stopwords and extracts only nouns for keyword network analysis and so on.

• Advances in aircraft and spacecraft science
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• v.8 no.4
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• pp.345-372
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• 2021

The analysis of nonlinear vibrations, buckling, post-buckling, flutter boundary determination and post-flutter behavior of a homogeneous curved plate assuming cylindrical bending is conducted in this article. Other assumptions include simply-supported boundary conditions, supersonic aerodynamic flow at the top of the plate, constant pressure conditions below the plate, non-viscous flow model (using first- and third-order piston theory), nonlinear structural model with large deformations, and application of mechanical and thermal loads on the curved plate. The analysis is performed with constant environmental indicators (flow density, heat, Reynolds number and Mach number). The material properties (i.e., coefficient of thermal expansion and modulus of elasticity) are temperature-dependent. The equations are derived using the principle of virtual displacement. Furthermore, based on the definitions of virtual work, the potential and kinetic energy of the final relations in the integral form, and the governing nonlinear differential equations are obtained after fractional integration. This problem is solved using two approaches. The frequency analysis and flutter are studied in the first approach by transferring the handle of ordinary differential equations to the state space, calculating the system Jacobin matrix and analyzing the eigenvalue to determine the instability conditions. The second approach discusses the nonlinear frequency analysis and nonlinear flutter using the semi-analytical solution of governing differential equations based on the weighted residual method. The partial differential equations are converted to ordinary differential equations, after which they are solved based on the Runge-Kutta fourth- and fifth-order methods. The comparison between the results of frequency and flutter analysis of curved plate is linearly and nonlinearly performed for the first time. The results show that the plate curvature has a profound impact on the instability boundary of the plate under supersonic aerodynamic loading. The flutter boundary decreases with growing thermal load and increases with growing curvature.

• Journal of the Korean Dietetic Association
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• v.29 no.1
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• pp.49-64
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• 2023

Osteoporosis is a major health problem confronting middle-aged women today. Enhancing calcium intake in early adulthood can increase the rate of calcium gain in bone. In this study, we investigated the association of bone health-related nutritional knowledge levels with calcium-related dietary behavior and nutrition education among women. Data were collected using questionnaires from 347 women aged 20~30 residing in Gyeonggi-do. Subjects were categorized into two groups according to their bone health-related nutritional knowledge (high or low-knowledge group). Knowledge related to bone health and calcium, and dietary habits was assessed, and the preference for and intake frequency of calcium-rich food were collected and analyzed using food frequency questionnaires. The high-knowledge group showed a significantly higher rate of nutritional education experience (33.9%) when compared with the low-knowledge group (18.9%). Not only were the perceptions regarding milk and dairy products more positive in the high-knowledge group (P<0.05), but the intake frequency of calcium-rich foods, such as tofu, soybean, and anchovies, was also higher in this group compared to the low-knowledge group (P<0.05). Overall, the preference for all calcium-rich foods was positively correlated to their intake frequency (P<0.05). Nutrition education experience and the recognition of the need for such education were positively correlated with the bone health-related nutrition knowledge score (P<0.05). In conclusion, bone health-related nutritional knowledge can affect calcium-related dietary behavior and increase the intake of calcium-rich food of 20~30-year-old women and this can contribute to the prevention of osteoporosis. To improve bone health-related nutritional knowledge among young women, it may be important to provide nutrition education.

• Journal of the Korea Society of Computer and Information
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• v.29 no.5
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• pp.67-74
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• 2024

As the number of coffee shops increases, many people are studying or working at coffee shops. Coffee shop operators have been required to analyze customer visits due to customer turnover and profit problems. Methods such as image analysis, QR code authentication, and Bluetooth beacon have been proposed for these statistics and analysis. However, it is difficult to use due to problems such as invasion of privacy and low accuracy. Therefore, in this study, to solve these problem and provide more accurate in-store congestion information, we propose a crowding measurement method of coffee shop using high frequency signal. There is an advantage in that a high frequency signal replaces the Bluetooth signal, and the transmission range of the signal is limited to the store, thereby increasing the accuracy of the method. To verify the performance of the proposed system, we conducted a comparative experiment with a Bluetooth based system, and as a result, the proposed method showed lower misrecognition rate. Thus, the proposed method will be an effective useful service for providing information on crowding at coffee shops and processing statistics.

• Advances in concrete construction
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• v.17 no.3
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• pp.151-158
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• 2024

The calculation of the natural frequencies versus Young's modulus of carbon nanotubes with modified continuum shell is the subject of current research. When designing these tubes, it is important to understand their frequencies because excessive vibrations might cause fatigue. These tubes are designed and built to meet specific needs and have been suitably modified to investigate their vibratory response. There are numerous uses for carbon nanotube free vibration analysis in the mechanical sciences. The fundamental frequency with Young's modulus for clamped-free and simply supported end conditions, which is connected to the carbon nanotubes, is calculated theoretically for chiral single carbon nanotubes. When Young's modulus rises, so does the frequency curve pattern. Young's modulus influences the single-walled carbon nanotube's dynamic response by simulating it as a modified continuum shell. The Young's modulus of chiral tube and the value of frequency increased as the chiral tube's index increased. The results are checked against past studies to ensure the problem's validity and are determined to be accurate.

• Korean Journal of Childcare and Education
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• v.11 no.4
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• pp.271-292
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• 2015

The purpose of this study was to examine the mediating effect of young children's self-control in the relationship between mother's affectionate parenting psychological behavioral control and young children's problem behaviors. The subjects of this study were 368 mothers whose young children were 3 to 5years old and attending to 3 private kindergartens and 2 child-care centers located in Chunkbuk. Data were analyzed by frequency, percentage, Primary factor analysis, Cronbach's ${\alpha}$, t-test, F-test, Pearson's correlation, and hierarchical regression, using the SPSS 12.0 program. The results of this study were as follows: First, young children's self control partially mediated when mother's affectionate parenting affected young children's internalizing and externalizing problem behaviors. Second, young children's self control partially mediated when mother's psychological control affected young children's internalizing and externalizing problem behaviors. Third, young children's self control did not show a mediating effect on the relationship between mother's behavioral control and young children's internalizing and externalizing problem behaviors. In conclusion, young children's internalization of mother's psychological control and behavioral control as well as affectionate parenting have its effect on problem behaviors.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1460-1471
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• 2019

This study applied the PBL class to the 'Nursing Process and Critical Thinking' courses in the second semester of 2018, and is a primitive research that utilized a single-group, pretest-posttest experimental design in order to examine the effects of the class on Critical Thinking Disposition, Problem Solving Ability, and Professional Self-Concept. Self-report questionnaires were administered to 59 nursing college students in G province. The PBL class consisted of 8 weeks of traditional lectures and 4 weeks of PBL classes. The SPSS/WIN 23.0 program was used for data analysis. Frequency and percentage were used to analyze the general characteristics, and mean, standard deviation and paired t-test were used to analyze the difference between the two groups. As a result, the Critical thinking Disposition of nursing college students was significantly increased(t=4.39, p<.001) after PBL class(3.71±.36) than before PBL class(3.41±.40). The Problem Solving Ability was notably improved(t=3.97, p<.001) after PBL class(3.70±.59) than before PBL class(3.36±.38). The Professional Self-Concept was considerably increased(t=4.84, p<.001) after PBL class(3.22±.50) compared to before PBL class(2.92±.28). Therefore, applying Problem-Based Learning in nursing education to a greater extent is estimated to be effective in increasing the core competencies of nursing college students.

• Journal of Gifted/Talented Education
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• v.24 no.6
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• pp.961-974
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• 2014

We analyzed the relationship between the brain Dominance and the scientific creative problem solving utilizing propensity to target Science-Gifted Student (n=159). Brain dominance is divided into left upper brain (LUB), left lower brain (LLB), right lower brain (RLB), and right upper brain (RUB). Creative problem solving skill in science included validity, scientific characteristics, sophistication, originality, and fluency. Analysis of the results of this study showed a high frequency among the four types of the brain dominance is the highest score of LUB in science gifted group. This point was found that the tendency of the analytical and critical thinking that is characteristic of the LUB is strong scientific gifted group. When total sample was divided into high and low groups by scientific creative problem solving scores, in the analysis of the brain dominance score difference between the two groups of students who take advantage of the results of score RUB is compared to the high fluency group score higher than the low group found (p<0.05). The analysis of the correlation between brain dominance and scientific creative problem solving showed that originality and fluency had statistically significant correlation with RUB propensity score (p<0.05). This result suggests that the imaginative and challenging RUB propensity may be related to produce many and original ideas in scientific creative problem solving.

• Korean Journal of Childcare and Education
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• v.10 no.6
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• pp.165-184
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• 2014

The purpose of this study is to examine the effect of SNS use by prospective early childhood teachers in PBL class on flow and problem-solving skills. For this purpose, the PBL class was conducted for eight weeks with 44 prospective students in the early childhood social studies course, and measured the classroom situation in terms of usefulness of SNS, flow, and problem-solving skills by using a cognitive test. To analyze the measured values, frequency analysis, reliability analysis, factor analysis, and correlation analysis were performed. Also, to verify the hypotheses set in this study, structural equation modeling was used based on AMOS. The result is as follows: First, in PBL-based class, use of SNS had a positive effect on flow. Second, flow had a direct influence on problem-solving skills. Third, however, use of SNS did not have a direct influence on problem-solving skills and, therefore, flow plays a mediating role for problem-solving skills. Based on the result, in the study, it was found that the use of SNS in PBL class can increase interest, motivation, and participation of students and they then become more willing to contribute to class activities.