• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.180-184
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• 2007

For driving a sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, a $120^0$ delayed three phase sinusoidal current input which matched with the absolute rotor position is needed at a stator coil. So, the detection of absolute rotor position is required inevitably. Thus the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. This study purposes to design signal processing logic circuits which can detect the absolute position of motor with a modem encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• Journal of Gifted/Talented Education
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• v.18 no.3
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• pp.443-464
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• 2008

This study analyzes the surveys of attitudes toward science, the peer relationship, the achievement motivations, and the parents' attitudes to science gifted education. It have been conducted to 53 scientifically gifted and 120 non-gifted students. The findings from the analyses suggest that there exist few meaningful differences in the attitude toward science, the motive for achievements and the peer relationship except in the parents' attitude to the gifted student education. This means that the recognition and the attitude of the parents have great influences on non-gifted students especially female students in the process of resolving to take future directions to science fields and choosing the gifted education center. Accordingly, we are in dire need of the changes in the social recognition of science and it is strongly recommended to seek for the ways of promoting science and supporting engineering graduates at the level of nation, thereby establishing legal and institutional foundations to make effective human resource arrangements.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1018-1024
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• 2011

For the driving of the sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, the 1200 delayed three phase sinusoidal current inputs which matched with the absolute rotor position are needed at the stator coil. Therefore, the detection of a absolute rotor position is required inevitably. And the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. The purposes of this study are to design signal processing logic circuits which could detect the absolute position of motor with a modern encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.4
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• pp.291-299
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• 2007

To operate a permanent magnet synchronous motor (PMSM) at a maximum torque per ampere (MTPA) operation point, the exact values of machine parameters such as inductances and back-EMF constant, which are sensitive to motor phase currents and temperature respectively, should be blown. An adaptive estimation method for on-line estimation of the machine parameters is not suitable for practical applications since it has difficulties in estimating exact values and requires complex mathematical calculations. The purpose of this paper is to present a simple MTPA operation point tracking control strategy for vector controlled PMSM drives with slow dynamic loads. The proposed method searches MTPA operation points by modulating current phase angle and observing the variation in command power. The current angle modulation strategy is designed to sense the effect of load variations in the command power. Therefore, the proposed method can track the MTPA operation points of the PMSM regardless of load variations. Computer simulation and experimental study is also presented to show the effectiveness of the proposed method.

• Journal of Digital Convergence
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• v.19 no.2
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• pp.471-479
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• 2021

The purpose of this study is to find out what meanings would be brought to the old females' lives, who took part in the line dance as programs for senior's health. 6 the old females were selected. Research materials were gathered from in-depth interviews and observations by researcher. As a result of content analysis, the following conclusions were drawn. First, elderly's motives for participation in line dance were found to be solicitation of the surroundings, recovery and maintenance of health, and participation in pursuit of happiness. Second, the elderly's line dance experience was changed the perception of dance. Third, line dance improved interest and confidence in the body and appearance. Fourth, the line dance experience provides a space for making new friends. Fifth, the line dance experience improved a sense of accomplishment and immersion through dance. Sixth, the support and praise of the family increased self-esteem and improved overall life satisfaction and happiness.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.579-583
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• 2024

The purpose of this study was to examine the effect of entrepreneurial environment factors on the entrepreneurial intentions of college students. The results of the study were as follows. Looking at the average of entrepreneurial intention, it was 3.05 out of 5 points, and the average of start-up environmental factors was 3.65 points for subjective norms, 3.57 points for entrepreneurial attitude, 3.56 points for intrinsic motivation, and 2.75 points for behavior control. Extrinsic motivation was followed by 2.58 points. When examining the correlation between the entrepreneurial environment factors of college students' entrepreneurial intention, it was found that they have a static correlation coefficient, and as a result of analyzing the effect of the start-up environmental factors on the entrepreneurial intention, it was found that the entrepreneurial attitude (t = 3.269, p<.001), behavior control (t = 5.603, p<.001), intrinsic motivation (t = -3.812, p<.001), and extrinsic motivation (t = -2.887, p<.01) had an effect on the entrepreneurial intention.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.5
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• pp.15-26
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• 2015

Overall, college students tend to be immersed in the relatively safe employment, such as civil servants or public sector than start one's own business due to the lack of entrepreneurial spirit which made the great success in order to take the risk and innovative challenge. In this study, relationship between pre-founder of college students' self-determination, entrepreneurship, entrepreneurial intentions are to be determined. As a result, the implications were derived in order to make pre-founder various ways of career decision beside employment. Therefore start-up training courses was verified by moderating effects. The results are first, high self-determination(Autonomy, Efficacy) of the pre-founder made positive impact on entrepreneurial intention. Second, high self-determination(Autonomy, Efficacy) of the pre-founder made positive impact on entrepreneurship. Third, entrepreneurship of the pre-founder made positive impact on entrepreneurial intention. Fourth, entrepreneurship was carried out a full mediating role in the relationship between self-determination and entrepreneurial intention. Finally, Pre-founder group who have taken entrepreneurship education have showed a positive relationship between high self-determination(Autonomy, Competence, Relationship) and entrepreneurial intention. Based on these results, especially pre-founders, in order to improve the willingness of university students entrepreneurship, highly motivated intrinsic motivation is needed to ensure the student's self-determination in University education. It looks that can be achieved through the strengthening of entrepreneurship education for autonomy, competence, efficacy improvement.

• Journal of the Korea Society of Computer and Information
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• v.19 no.9
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• pp.65-73
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• 2014

Since Time synchronization is also critical in Wireless Sensor Networks (WSN) like other networks, a time synchronization protocol for WSN called IBS(Indirect-Broadcast Synchronization) has been already proposed in 2012. As IBS operates in cluster tree topology, network lifetime may be mainly shortened by cluster head node[s], which usually consumes more power than cluster member (i.e. non-cluster head) nodes. In this paper, I propose enhanced version of IBS (called EIBS) which saves overall energy and prolongs network lifetime by re-constructing partial cluster tree locally. Compared with other tree construction approaches, this tree reconstruction algorithm is not only simpler, but also more efficient in the light of overall power consumption and network lifetime.

• The Korean Journal of Rehabilitation Nursing
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• v.14 no.1
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• pp.24-31
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• 2011

Purpose: The purpose of this study was to identify related factors of stress, social support and rehabilitation motivation of stroke survivors and analyze their relationship. Method: A sample of 106 stroke survivors completed face-to-face interviews. The levels of stress, social support and rehabilitation motivation were measured by the Neuman's stress, Multidimentional Scale Perceived Social Support and Han's Rehabilitation Motivation, respectively. The t-test, ANOVA, and Pearson correlation were conducted using the SPSS 17.0. Results: The mean scores of stress, social support and rehabilitation motivation were 3.3 (SD=0.76), 3.2 (SD=0.88), and 3.4 (SD=0.49) respectively. Compared to stroke survivors who had no spouses, those with spouses had a lower level of stress (t=9.52, p=.003), a higher level of social support (t=7.32, p=.008) and a higher level of rehabilitation motivation (t=15.39, p=.001). The rehabilitation motivation was significantly higher in stroke survivors with higher education (F=5.00, p=.001), more monthly income (F=15.39, p=.001), greater income satisfaction (F=3.80, p=.026), shorter duration of disease (F=3.64, p=.030) and absence of dysarthria (t=6.81, p=.010). Stress, social support and rehabilitation motivation are significantly related with each other. Conclusion: The findings suggest that these significant factors should be considered when caring for stroke survivors.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.8-30
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• 2018

The purpose of this study was to investigate the relationship between empowering leadership, directive leadership, safety communication, and safety behavior. Also, we examined whether safety motivation had a moderated mediating effect on this relationship. We collected the surveys from 343 combat pilots of the Republic of Korea Air Force for the analysis. Our structural equation modeling analysis revealed that there was a positive relationship between empowering leadership and safety behavior, and safety communication fully mediated the relationship. However, there is no relationship between directive leadership and safety behavior. Also, our results showed that safety motivation moderated the relationship between empowering leadership and safety communication, but not the relationship between directive leadership and safety communication. Furthermore, the relationship between empowering leadership and safety behavior through safety communication varied significantly with the degree of safety motivation, such that the higher the safety motivation, the higher the impact of empowering leadership on safety behavior through safety communication. Finally, we discussed the implications of these results, study limitations, and practical suggestions for future research.