• Transactions on Electrical and Electronic Materials
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• v.6 no.5
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• pp.193-197
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• 2005

We investigated fault current limiting characteristics of the flux-lock type superconducting fault current limiter (SFCL), which consisted of a primary winding and several secondary windings connected in series between $high-T_C$ superconducting (HTSC) thin films. Each YBCO thin film has a 2 mm wide and 42 cm long meander line with 14 stripes of different length. The power imbalance due to the slight difference of Ie between YBCO current limiting elements causes the significant power burden on YBCO element with lower $I_C$. We confirmed from our experiments that the mutual coupling between the primary winding and secondary windings of the flux-lock type SFCL reduced the power imbalance between YBCO current limiting elements compared with the resistive type SFCL connected in series.

• Child Health Nursing Research
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• v.23 no.3
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• pp.312-318
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• 2017

Purpose: In this study factors affecting quality of life in mothers who have children with precocious puberty were identified. Methods: The participants were 102 mothers of children with precocious puberty. From September 12 to September 30, 2016, data were collected using a structured questionnaire and analyzed using SPSS/WIN 22.0. Results: Regression analysis showed that the model's explanatory power was 45%(F=28.71, p<.001). Role stress (t=-4.83, p<.001), objective burden (t=-2.71, p<.001), and average monthly income (t=4.12, p<.001) were factors affecting quality of life among these mothers. The most influential factor was role stress (${\beta}=-.41$), which showed a negative correlation. Conclusion: Role stress and objective burden were major factors that decreased the quality of life in these. The findings indicate that effective strategy programs for reducing role stress and objective burden are necessary to improve the quality of life in mothers of children with precocious puberty.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.863-869
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• 2005

We investigated quench characteristics of superconducting elements connected in series and parallel each other. The serial and parallel connections of superconducting elements causes a difficulty in simultaneous quench due to slight difference between their critical current densities. In other to induce simultaneous quench, we fabricated four type circuits; serially connected circuit before parallel connection, the circuit connected in parallel before serial connection, serially connected circuit before parallel connection with reactors, the circuit connected in Parallel before serial connection with reactors. We confirmed that the simultaneous quenches occurred in serial and parallel connections of superconducting elements using reactors. In addition, the power burden of superconducting elements was smaller than those of serial and parallel connections of superconducting elements without reactors.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.412-415
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• 2005

The recent requirement for faster and more frequent solutions has encouraged the consideration of parallel implementations using decentralized processors. Distributed multi-processor environments can potentially greatly increase the available computational capacity and decrease the communication burden, allowing for faster Optimal Power Flow (OPF) solutions. This paper presents a mathematical approach to implementing distributed OPF using the alternating direction method (ADM) to parallelize the OPF. Several IEEE Reliability Test Systems were adopted to demonstrate the proposed algorithm.

• The Journal of Korean Academic Society of Nursing Education
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• v.15 no.2
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• pp.311-320
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• 2009

Purpose: This study was done to investigate the factors associated with a mothers' caring behavior in health promotion of children with disabilities. Methods: Data were collected by using self-reported questionnaires from 371 mothers who had a 3-12 year old child with a disability from July 14 to 31, 2008. Data were analyzed by descriptive statistics, t-test, one-way ANOVA, and hierarchical multiple regression analysis with the SPSS program. Results: There were significant differences on the mothers' caring behavior according to children's negative and hyperactive behavior, mothers' perceived burden, parenting efficacy, and social support. Children's characteristics explained 5.1% of mothers' caring behavior. The power of explanation ($R^2$) was 16.6% by adding mother's characteristics including mother's job, burden, parenting efficacy, satisfaction and stigma, and increased to 23.5% by adding social support. Conclusion: These results showed that mothers' caring behavior for their children's health promotion could be influenced by children's behavior problems, mothers' perception of burden, parenting efficacy, and social support. It suggests that health promotion programs for children with disabilities should focus on lowering subjective burden and enhancing mother's efficacy as a type of social support.

• The Korean Journal of Emergency Medical Services
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• v.26 no.3
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• pp.7-19
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• 2022

Purpose: The purpose of this study was to confirm the exploratory factor analysis and reliability analysis of the burden of 119 emergency medical technicians. Methods: The data collection period was from November 2, 2022 to November 6, 2022. This study had 316 subjects, and the collected data were analyzed using exploratory factor analysis and Cronbach's α coefficient using IBM SPSS statistics 27.0. Results: The reliability was .924. The exploratory factor analysis yielded the following information: the first factor was lack of violence policy, the second factor was conflict between the organization and the paramedics, the third factor was lack of psychological support, and the fourth factor was lack of education and communication. The explanation power of 4 factors was 54.31%. Conclusion: This study is significant as it performs exploratory factor analysis as a preliminary step in the development of a burden measurement tool.

• Korean Journal of Rural Living Science
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• v.4 no.1
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• pp.45-56
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• 1993

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.96-96
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• 2005

• Journal of Power Electronics
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• v.17 no.1
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• pp.76-87
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• 2017

Finite-set predictive current control (FS-PCC) is advantageous for power converters due to its high dynamic performance and has received increasing interest in multilevel inverters. Among multilevel inverter topologies, the cascaded H-bridge (CHB) inverter is popular and mature in the industry. However, a main drawback of FS-PCC is its large computational burden, especially for the application of CHB inverters. In this paper, an FS-PCC method based on a deadbeat solution for three-phase zero-common-mode-voltage CHB inverters is proposed. In the proposed method, an inverse model of the load is utilized to calculate the reference voltage based on the reference current. In addition, a cost function is directly expressed in the terms of the voltage errors. An optimal control actuation is selected by minimizing the cost function. In the proposed method, only three instead of all of the control actuations are used for the calculations in one sampling period. This leads to a significant reduction in computations. The proposed method is tested on a three-phase 5-level CHB inverter. Simulation and experimental results show a very similar and comparable control performance from the proposed method compared with the traditional FS-PCC method which evaluates the cost function for all of the control actuations.

• Journal of Power Electronics
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• v.17 no.3
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• pp.674-685
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• 2017

The conventional model predictive direct torque control (MPDTC) method uses all of the voltage vectors available from a two level voltage source inverter for the prediction of the stator flux and stator current, which leads to a heavy computational burden. This paper proposes an improved model predictive direct torque control method. The stator flux predictive controller is obtained from an analysis of the relationship between the stator flux and the torque, which can be used to calculate the desired voltage vector based on the stator flux and torque reference. Then this method only needs to evaluate three voltage vectors in the sector of the desired voltage vector. As a result, the computational burden of the conventional MPDTC is effectively reduced. The time delay introduced by the computational time causes the stator current to oscillate around its reference. It also increases the current and torque ripples. To address this problem, a delay compensation method is adopted in this paper. Furthermore, the switching frequency of the inverter is significantly reduced by introducing the constraint of the power semiconductor switching number to the cost function of the MPDTC. Both simulation and experimental results are presented to verify the validity and feasibility of the proposed method.