• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.10
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• pp.2338-2356
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• 2013

In cognitive radio networks, acquiring the position information of the primary user is critical to the communication of the secondary user. Localization of primary users can help improve the efficiency with which the spectrum is reused, because the information can be used to avoid harmful interference to the network while simultaneity is exploited to improve the spectrum utilization. Despite its inherent inaccuracy, received signal strength based on range has been used as the standard tool for distance measurements in the location detection process. Most previous works have employed the path-loss propagation model with a fixed value of the path loss exponent. However, in actual environments, the path loss exponent for each channel is different. Moreover, due to the complexity of the radio channel, when the number of channel increases, a larger number of RSS measurements are needed, and this results in additional energy consumption. In this paper, to overcome this problem, we propose using the Bayesian compressive sensing method with a calibrated path loss exponent to improve the performance of the PU localization method.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 1992.11a
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• pp.56-59
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• 1992

Adaptive active attenuation of noise in a duct is considered. A duct is modelled when the acoustic feedback exists. The secondary path transfer function is estimated using multiple model approaches. An IIR structure is assumed for the control filter, and the recursive least mean squares algorithm is used to adjust the filter coefficients.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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• pp.192-202
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• 2009

Disassembly of products at their end-of-life (EOL) is a prerequisite for recycling or remanufacturing, since most products should be disassembled before being recycled or remanufactured as secondary parts or materials. In disassembly sequence planning of EOL products, considered are the uncertainty issues, i.e., defective parts or joints in an incoming product, disassembly damage, and imprecise net profits and costs. The paper deals with the problem of determining the disassembly level and corresponding sequence, with the objective of maximizing the overall profit under uncertainties in disassembly cost and/or revenue. The solution is represented as the longest path on a directed acyclic graph where parameter (arc length) uncertainties are modeled in the form of intervals. And, a heuristic algorithm is developed to find a path with the minimum worst case regret, since the problem is NP-hard. Computational experiments are carried out to show the performance of the proposed algorithm compared with the mixed integer programming model and Conde's heuristic algorithm.

• Journal of Power Electronics
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• v.19 no.2
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• pp.403-412
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• 2019

Aiming at the problems of large dv/dt and di/dt in traditional single-ended converters and high electromagnetic interference (EMI) noise levels, a single-ended isolated converter using the secondary resonance technique is proposed in this paper. In the proposed converter, the voltage stress of the main power switch can be reduced and the voltage across the output diode is clamped to the output voltage when compared to the conventional flyback converter. In addition, the peak current stress through the main power switch can be decreased and zero current switching (ZCS) of the output diode can be achieved through the resonance technique. Moreover, the EMI noise coupling path and an equivalent model of the proposed converter topology are presented through the operational principle of the proposed converter. Analysis results indicate that the common mode (CM) EMI noise and the differential mode (DM) EMI noise of such a converter are deduced since the frequency spectra of the equivalent controlled voltage sources and controlled current source are decreased when compared with the traditional flyback converter. Furthermore, appropriate parameter selection of the resonant circuit network can increase the equivalent impedance in the EMI coupling path in the low frequency range, which further reduces the common mode interference. Finally, a simulation model and a 60W experimental prototype of the proposed converter are built and tested. Experimental results verify the theoretical analysis.

• Research in Community and Public Health Nursing
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• v.29 no.2
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• pp.184-193
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• 2018

Purpose: The aim of this study is to examine a path model on the relationship among social capital, physical activity and subjective health status in the community indwelling elderly. Methods: The study was conducted utilizing the 2014 Seoul Survey, in the method of analyzing cross-sectional design and secondary data. Among 45,497 participants in total, the data of 4578 adults aged 65 or above was analyzed. Social capital was measured by social trust and social participation. Physical activity was measured by regular exercise. Additionally, a numerical rating scale was used to assess subjective health status. The data were analyzed using descriptive statistics, Pearson's correlation coefficients and path analysis. Results: Social participation and physical activity showed a direct effect on subjective health status in community indwelling elderly while social trust and physical activity showed an indirect effect on their subjective health status. The hypothetical path model of community indwelling elderly's subjective health status was proved correct. Conclusion: Findings from this study indicate that health-promoting intervention for community indwelling elderly should consider social trust and participation.

• International Journal of Advanced Culture Technology
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• v.6 no.3
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• pp.1-11
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• 2018

The purpose of this study is to develop and analyze the meaning and contents of the "H-STEAM teaching & learning model" which combines Science, Technology, Engineering, Arts & Mathematics (STEAM) with the elements of Humanities. We developed this model based on the key competencies linked with career path for middle school students in Korea, with the recognition of two issues. First, the existing Korean STEAM education lacks the elements of humanities, thus failing to achieve an authentic convergence education. Second, it is necessary to develop a program that might correspond to the Free Semester Program that was first introduced in 2013, and implemented at full scale in 2016 for middle school students in Korea. The advantages of H-STEAM are as follows: First, H-STEAM enables students to flexibly think while traversing the physical world and the symbolic world in the process of dealing with the daily problems. Second, it combines advanced technology with human sensibility and imagination, and enables students to derive creative outcomes that stimulate their minds. Third, it makes students feel and realize a point of contact between the subject that students learn, and jobs of the real world.

• Korean Journal of Hydrosciences
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• v.3
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• pp.45-59
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• 1992

The flow characteristics varying with rate of the radius of curvature to width (Rc/B) in open channel bends are investigated with a simplified numerical model. Secondary flow velocity and transverise bed slope are formulated from the equations of momentum and force balance analysis, respectively. The conservation equations of mass and streamwise momentum are simplified by depth integration and its solution could be obtained from the explicit finite difference method. Three sets of computer simulation are executed. The rates of Rc/B adopted in simulations are 2.7, 5.4 and 8.1. The terms analyzed in this paper secondary flow velocity, streamwise velocity, the path of maximum steamwise velocity, deviation angle, and mass-shift velocity.

• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.31-41
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• 2009

In the Semantic Web, it is possible to provide intelligent information retrieval and automated web services by defining a concept of information resource and representing a semantic relation between resources with meta data and ontology. It is very important to manage semantic data such as ontology and meta data efficiently for implementing essential functions of the Semantic Web. Thus we propose an index structure to support more accurate search results and efficient query processing by considering semantic and structural features of the semantic data. Especially we use a graph data model to express semantic and structural features of the semantic data and process various type of queries by using graph model based path expressions. In this paper the proposed index aims to distinguish our approach from earlier studies and involve the concept of the Semantic Web in its entirety by querying on primarily extracted structural path information and secondary extracted one through semantic inferences with ontology. In the experiments, we show that our approach is more accurate and efficient than the previous approaches and can be applicable to various applications in the Semantic Web.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.14 no.1
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• pp.1-14
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• 2010

Backgrounds : Bojungikgitang is one of the most common herbal prescriptions in Oriental Medicine, and it is highly recommended prescription for Nogwonsang syndrome. The Author developed Nogwonsang questionnaire for quantitative evaluation. Nogwonsang questionnaire is consisted of causes that induce fatigue, symptoms that directly associated with fatigue, and secondary symptoms that is induced from fatigue. Purposes : This study aims to verify whether the Bojungikgitang Questionnaire has causality and meaningful path structure by path analysis. Methods : 242 patients from 12 OMD clinics participated in this study. The patients executed a question investigation in the object. Factor analysis was conducted for extraction of factor and abridgment of items. Path analysis was conducted to verify path structure. SPSS 15.0 for Windows and AMOS 7.0 were used for statistical analysis. Results : Overwork factor explains fatigue factor. Coefficient is 0.771. Fatigue factor explains digesting and cold factor. Individually coefficient is 0.632 and 0.465. Model fit is $X^2=61.395$(df=51), GFI=0.960, AGFI=0.939, NFI= 0.924, CFI=0.986, RMSEA=0.029. Path structure is proved to be significant. Conclusions : Further research is needed Gold standard of Nogwonsang. Establishment of Gold standard leads and the collection of data and the research which are objective are possible. Connection of the clinical indexes which are objective on the paperweight outside and leads and the development of the diagnosis tool which is fixed quantity is demanded.

• Journal of the Korea Society of Computer and Information
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• v.27 no.11
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• pp.305-314
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• 2022

In this paper, we propose a "social mentality" of primary and secondary school teachers in Anshan City, China. To conduct the study, 298 teachers in Ansan City were selected and a survey was conducted. This study adopted the method of combining literature research and questionnaire survey. The results showed that the overall level of "social mentality" of primary and secondary school teachers in Anshan was relatively high. Teachers' social support levels differed significantly from educational background, teaching section, administrative position, and school location. The path model shows the interaction mechanism between variables. It appeared that general self-efficacy and job involvement play an important role in the mechanism.