• Journal of Korean society of Dental Hygiene
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• v.6 no.2
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• pp.129-141
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• 2006

This study attempts to provide basic information that is necessary to establish the direction of oral health education process abd to develop effective oral health promoting programs for college students by analyzing the modifying factors that may affect their oral health behaviors and their cognitive and perceptive factors. Data for this study are collected by the questionnaire method from college students who attend colleges located Chungchong and Busan province for the period between June 20, 2006 and July 30, 2006. The respondents were chosen from Dental department and Non-Dental department. After omitting the responses with insufficient information, 409 valid responses are used for this analysis. The major finding of the present study are as follows: 1. Oral health behaviors factor is higher rate dental department than non-dental department, dental department than non-dental department appear significant the oral health education, the lasted year round oral examination, the used of oral hygiene supplies, oral prevention treatment. 2. Oral health behaviors and perception-awareness factor is higher score dental department than non-dental department and self efficiency is similar. Oral health behaviors is higher score dental department, the barriers to oral health behaviors is similar. The benefits of oral health behavior is higher score dental department. 3. The oral health behavior is higher dental department. In dental department the overall average score for oral health behaviors question is the correct teeth-brushing, self-restraint of liquor and cigarettes. Non dental department the overall average score for oral health behaviors question is the correct teeth brushing, good nutrition. The lower average score is scaling and periodic oral examination. 4. The correlation coefficient analysis between oral health behaviors and perception-awareness factors, variables which appear significant correlation coefficient by the self-efficiency are the control of oral health, the benefits of oral health behaviors, behavior of oral health, variables which appear significant correlation coefficient by the control of oral health are the benefits of oral health behaviors, the knowledge of oral health, behavior of oral health. And variables which appear significant correlation coefficient by the barriers to oral health behaviors is the benefits of oral health behaviors, variables which appear significant correlation coefficient by the knowledge of oral health is oral health behaviors.

• Journal of Korean society of Dental Hygiene
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• v.15 no.1
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• pp.111-118
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• 2015

Objectives: The aim of the study is to investigate the health belief model affecting the oral health behavior in middle and high school students. Methods: The subjects were 296 middle and high school students in Seoul, Gyeonggi and Incheon from February 15 to March 21, 2014. The students filled out the self-reported questionnaires after receiving informed consents. The instrument was adopted and revised from those of Kim & Hwang, and Choi & Joo. The questionnaire consisted of 4 questions of general characteristics, 9 questions of oral health status including subjective oral health status, frequency of tooth brushing, duration of tooth brushing, method of tooth brushing, use of oral health devices, dental clinic visit, scaling services, snack intake, and smoking. The oral health belief consisted of 25 questions including susceptibility, seriousness, barriers, benefit, and self-efficacy using Likert 5 scale. The reliability of Cronbach's alpha in the study was 0.725. Data were analyzed using SPSS ver 18.0 for frequency analysis, t-test, ANOVA, ${\chi}^2$-test, and Pearson's correlation coefficient, simple regression, and binary logistic regression. Results: Oral health beliefs of middle and high school students affected the oral health behaviors. Susceptibility, barriers and self-efficacy also influenced on the oral health behaviors. In order to provide the best oral health education, susceptibility and self-efficacy are the primary factors to increase motivation because the motivation endows the students with correction of oral health behaviors that improve the knowledge, attitudes, and decrease barriers in oral hygiene. Conclusions: It is important to correct oral health behaviors in the middle and high school students by providing the continuing and systematic oral health education.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.691-697
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• 2011

In this study, the vessel collision protective structure and the vessel were modeled numerically and the quasi-static collision analysis was performed to evaluate the maximum protection capacity. In the modeling process of protective structure, the nonlinear behaviors of structure and the supporting conditions of ground including pull-out action were considered. In that of collision vessel, the bow of vessel was modeled precisely, because of the nonlinear behaviors were concentrated on it. For the efficient analysis, the mass scaling scheme was applied, also. To evaluate the differences and efficiency, the dynamic analyses were performed for the same model, additionally. Based on the obtained energy dissipation curves of the structure and the vessel, the moment that the collision force affected to the bridge substructures was determined and the maximum allowable collision velocity was evaluated. Because of the energy dissipation bound can be recognized clearly, this scheme can be used efficient in engineering work.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.91-96
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• 1999

Semiconductive polyaniline and its derivatives such as poly(aniline-co-sodium diphenylamine sulfonate), poly (aniline-co-o-ethoxyaniline), poly (o-methylaniline), and poly (o-methoxyaniline) were synthesized, and then adopted as suspending particles of the electrorheological (ER) fluids. All suspensions of these polyaniline derivatives showed typical ER properties under high applied electric fields. However, flow behaviors are observed to be quite different depending on the polyaniline derivatives, especially in the stress plateau regions obtained at low shear rates. Using a scaling law, we also obtained universal cures of ER fluids from the flow curves at each applied electric field based on the relationship between the dynamic yield stress with the applied electric field and flow curve changes according to the electric fields.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.157-162
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• 2013

To analyze the dynamic acceleration characteristics, it is necessary to identify the acceleration model using some methods that can represent the dynamic properties well. In this sense, fractal methods were used for the verification of characteristics of an acceleration signal. To estimate and analyze the geometry of acceleration signal, a fractal interpolation and its analysis was introduced in this paper. The chaotic nature of acceleration signal was considered in fractal modeling. In this study the fractal signal modeling has brought a focus within the scope of the fractal interpolation and fractal dimension. And a new idea of fractal dimension has been introduced and discussed considering the damping ratio and amplitude for its dynamic properties of the signal. The fractal dimension of acceleration with respect to the scaling factor using fixed data points of 1000 points was calculated and discussed. The acceleration behaviors of this results show some different characteristics. And this fractal analysis can be applied to other signal analysis of several machining such as pendulum type grinding and milling which has many dynamic properties in the signal.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.81.2-81.2
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• 2016

Many signals in the nature have power-law behaviors, namely they are "scale-free". The method of detrended fluctuation analysis (DFA), as one of the popular methods (e.g., Rescaled range analysis and Spectral analysis) for determining scale-free nature of time series, has a very important advantage that the DFA can be applied to both stationary and non-stationary signals. The analysis of time series using the DFA has been broadly used in physiology, finance, hydrology, meteorology, geology, and so on. We performed the DFA of 16 Spaceweather HMI Active Region Patch (SHARP) parameters for 38 HMI Active Region Patches (HARPs) obtained by Solar Dynamics Observatory (SDO) from May 2010 to June 2014. The main results from this study are as follows. (1) The most of the time series data are non-stationary. (2) The DFA scaling exponents of "mean vertical current density" for 38 HARPs have a negative correlation coefficient (-0.41) with flare index. (3) The DFA scaling exponents of parameters such as "Sum of the absolute value of net currents per polarity", "Absolute value of the net current helicity", and "Mean photospheric excess magnetic energy density" for the most active HARPs having more than 10 major flares, have positive correlation coefficients (0.64, 0.59, and 0.53, respectively) with the ratio of "the number of CMEs associated with major flares" to "the number of major flares". Physical interpretations on our results will be discussed.

• Journal of the Korean Chemical Society
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• v.57 no.3
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• pp.365-369
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• 2013

With the wide application of ASP (alkaline-surfactant-polymer) flooding, the scaling becomes more and more serious, which is harmful to the oilfield and environment. In order to investigate the effects of HPAM on calcium carbonate crystallization, the crystallization behaviors of $CaCO_3$ in HPAM (Hydrolyzed polyacrylamide) solutions were studied and the composition and morphology of $CaCO_3$ crystal were investigated in different concentrations of polyacrylamide solutions. The crystal forms and morphologies of $CaCO_3$ were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that the crystallization of $CaCO_3$ is strongly influenced by the HPAM. The paper analyzed the internal cause, and the results show: The reasons leading to the change of morphology are carboxyl groups in polyacrylamide molecule and $Ca^{2+}$ in solution form chelates by coordination bond. And the chelates are adsorbed on the calcium hydroxide surfaces of solid-liquid interfaces so as to change the formation rate of calcium carbonate crystal nucleus. The research provides a reliable basis for the mechanism research of the scaling problem in the oil extraction process of ASP flooding and the adoption of scale inhibition and scale inhibitor.

• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1310-1317
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• 2017

GASFLOW-MPI is a widely used scalable computational fluid dynamics numerical tool to simulate the fluid turbulence behavior, combustion dynamics, and other related thermal-hydraulic phenomena in nuclear power plant containment. An efficient scalable linear solver for the large-scale pressure equation is one of the key issues to ensure the computational efficiency of GASFLOW-MPI. Several advanced Krylov subspace methods and scalable preconditioning methods are compared and analyzed to improve the computational performance. With the help of the powerful computational capability, the large eddy simulation turbulent model is used to resolve more detailed turbulent behaviors. A backward-facing step flow is performed to study the free shear layer, the recirculation region, and the boundary layer, which is widespread in many scientific and engineering applications. Numerical results are compared with the experimental data in the literature and the direct numerical simulation results by GASFLOW-MPI. Both time-averaged velocity profile and turbulent intensity are well consistent with the experimental data and direct numerical simulation result. Furthermore, the frequency spectrum is presented and a -5/3 energy decay is observed for a wide range of frequencies, satisfying the turbulent energy spectrum theory. Parallel scaling tests are also implemented on the KIT/IKET cluster and a linear scaling is realized for GASFLOW-MPI.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.776-792
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• 2021

Conventional integral effect test facilities were constructed to enable the precise observation of thermal-hydraulic phenomena and reactor behaviors under postulated accident conditions to prove reactor safety. Although these facilities improved the understanding of thermal-hydraulic phenomena and reactor safety, applications of new technologies and their performance tests have been limited owing to the cost and large scale of the facilities. Various nuclear technologies converging 4th industrial revolution technologies such as artificial intelligence, drone, and 3D printing, are being developed to improve plant management strategies. Additionally, new conceptual passive safety systems are being developed to enhance reactor safety. A new integral effect test facility having a noticeable scaling ratio, i.e., the (UNIST reactor innovation loop (URI-LO), is designed and constructed to improve the technical quality of these technologies by performance and feasibility tests. In particular, the URI-LO, which is constructed using a transparent material, enables better visualization and provides physical insights on multidimensional phenomena inside the reactor system. The facility design based on three-level approach is qualitatively validated with preliminary analyses, and its functionality as a test facility is confirmed through a series of experiments. The design feature, design validation, functionality test, and future utilization of the URI-LO are introduced.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.173-179
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• 2022

This study was conducted to provide basic data for the development of oral health education programs by examining oral health knowledge and oral health behaviors, and by identifying factors affecting oral health knowledge and scaling experience of Chinese domestic students. From March to May, a self-reported questionnaire was administered to 194 in the G area. The data were analyzed frequency analysis and independent t-test, multiple regression analysis, logistic regression analysis by using SPSS/WIN 26.0 program. The overall average of oral health knowledge was 13.83 out of 24, and knowledge of periodontal disease and scaling was the highest at 3.75, and knowledge of oral hygiene products was the lowest at 1.38. Oral health knowledge was significantly higher in those who had scaling experience for the past year, brushed teeth for more than 3 minutes at a time, used oral hygiene products, and had oral health education experience. As a result of multiple regression analysis, oral health education experience was the most important factor on oral health knowledge. As a result of logistic regression analysis, oral health knowledge was the most influential factor on scaling experience. It is necessary to expand education on the importance of oral care and actively introduce oral health management program for Chinese domestic students.