• Child Health Nursing Research
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• v.30 no.1
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• pp.67-74
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• 2024

Purpose: This study aimed to identify the general characteristics and health behaviors of students with non-therapeutic substance use. Methods: This secondary data analysis used data from the 17th Korea Youth Risk Behavior Web-based Survey (2021). Analyses of the 54,848 adolescents used descriptive statisics, the Rao-Scott χ² test, and logistic regression. Results: The risk factors for substance use among students were anxiety, loneliness, living separately from family, suicidal ideation, e-cigarette use, and high stress. Conclusion: The findings help identify the risk factors for non-therapeutic drug use among adolescents. Since South Korea does not have a drug prevention program for its adolescent population, an educational plan based on these findings could help prevent adolescent substance abuse.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.621-622
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• 2008

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.461-462
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• 2009

• Polymer Science and Technology
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• v.24 no.5
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• pp.528-534
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• 2013

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.582-588
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• 2014

The purpose of this study is to analyze how a joint research network between countries affects the diffusion of technology information and how much countries with high centrality on the network accept new technology and to seek their meaning. With this aim, the joint research network density between countries by year and the number of participating countries were measured using thesis information regarding the secondary battery field and the electric vehicle field, and a regression analysis of relevant variables was conducted. As a result of the analysis, the greater the joint research network density in the secondary battery field, the higher the number of participating countries in a linear relationship. Also, on the joint research network, countries with high degree centrality were discovered to have led development in the mid to large size secondary battery field. Meanwhile, for the electric vehicle field, although there appeared no increase in the network density value, the number of participating countries was found to have increased. This was analyzed that joint research between countries was not a necessary and sufficient condition although it played a crucial role in promoting technology diffusion. Such a result is meaningful in that it verified promoting factors for essential technology diffusion statistically; however, with this research, there exist limitations that the index of a central role on the network was measured only with degree centrality and that only the relationship between two players was measured for network density in interactions between players. Accordingly, it is necessary to carry out research into a method to measure interactions among multiple researchers in the future.

• Journal of the Korean Ceramic Society
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• v.40 no.4
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• pp.365-370
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• 2003

The phase development process of $Ba_2$ $Ti_{9}$ $O_{20}$ ceramics is not clearly known and frequently accompanies second phases which deteriorate dielectric properties. In synthesizing $Ba_2$ $Ti_{9}$ $O_{20}$ ceramics, in order to trace the reaction sequence during conventional solid-state reaction in BaO-Ti $O_2$ system, different barium sources of BaC0$_3$ and BaTi0$_3$ precursor were used as starting materials. From the analysis of XRD patterns, different secondary phases could be identified depending on the barium source used, which might mean that the equilibrium phases in BaO-Ti $O_2$ system are very difficult to be synthesized. Because the BaTi0$_3$ precursor provides short diffusion paths of ions, the system revealed less secondary phases during solid state reaction. In synthesizing BaO-xSm$_2$0$_3$-4.5Ti0$_2$ system using different barium sources, different secondary phases were developed also. Microstructure and dielectric properties were examined and discussed in terms of secondary phase development.

• Journal of KSNVE
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• v.7 no.4
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• pp.655-661
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• 1997

Base-isolation of a primary structure generally decrete the seismic response of its own and the secondary structure. It may cause an adverse effect on the seismic response of secondary system when the system is submerged and subject to a considerable hydrodynamic effect. In this paper, it is shown how, and how much, the base isolation of the primary structure can affect the secondary system response in extreme cases through dynamic analysis of a simplified coupled model for a submerged secondary system and a base-isolated primary structure. As an aseismatic design approach to reduce the response of the submerged system, optimization of the fluid gap, which controls the hydrodynamic mass effect, is performed. As an alternative approach in case where the control of fluid gap is unrealistic, application of base isolation to the submerged system is suggested. Effectiveness of various combinations of the primary base and secondary base isolations are compared.

• Journal of the Korean School Mathematics Society
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• v.23 no.3
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• pp.397-425
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• 2020

Statistical literacy is a key ability expected of citizens in information-laden societies, and is often revealed as an expected outcome of schooling and as a necessary component of adults' numeracy and literacy. Knowing how important statistical literacy is, the purpose of this research was to measure statistical literacy of adults and secondary mathematics teachers. This study explored the statistical literacy based on the level of understanding in poll results and analyzed the data obtained through semi-structured interviews with 20 secondary mathematics teachers and 20 adults. As a result, the following conclusions were obtained: First, few secondary mathematics teachers and adults correctly recognized the meaning of statistical terms and expressions included in the poll results. Second, 70% of research participants did not reach levels 3 or 4 of statistical literacy levels. Third, the statistical literacy level of secondary mathematical teachers was higher than that of adults.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.391-400
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• 2009

Recently, cellular communication networks are migrating from 2G to 3G. Spectrum utilization tends to be inefficient during the transition. Cognitive radio (CR) technology can be a key solution to increase spectrum efficiency by allowing secondary networks to utilize frequency resource of primary networks. However, conventional CR approaches which do not utilize the frequency reuse factor of primary networks may incur degradation of whole network performance. In this paper, we propose a mechanism that a secondary network senses pilot signals of a primary network and select optimum frequency bands. In order to maximize whole network performance, we formulate an optimization problem subject to interference constraints for a primary network and present algorithms. Simulation results compare the proposed method with the conventional method. Our proposed method shows performance gain over the conventional method if channel variation of a primary network is dynamic and the frequency reuse factor of a primary network is high.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.8
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• pp.39-45
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• 2012

This paper investigates the capacity for the secondary user with the primary full duplex relay (FDR) network in spectrum sharing systems. For sharing the spectrum of the primary user, sharing scheme under the various primary network should be investigated. However, the conventional works only consider the point-to-point primary communication system. When the FDR node is used for the primary networks, both primary relay and destination suffer the interference from the secondary transmitter simultaneously. Thus, the strict interference constraint should be considered to share the spectrum of the primary user. Therefore, we investigate the capacity of the secondary user with the primary FDR network under the average and peak received-power constraints. In addition, we analyze the performance degradation by the selection of the worst interference channels to consider interference constraint in this system. Through the numerical results, the capacities of the primary and secondary users under the average received-power is superior to the that under the peak received-power constraint.