• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.62-62
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• 2010

Photonic quasi-crystals(PQCs) have been fabricated by a multiple-exposure nanosphere lithography (MENSL) method using the self-assembled nanospheres as lens-mask patterns. The multiple-exposing source is collimated laser beam and rotation, tilting system. The arrays of the PQCs exhibited variable lattice structures and shape the control of ratating angle ($\theta$), tilting angle ($\gamma$) and the exposure conditions. The used nanosphere size is upto the $1\;{\mu}m$. Images of prepared 2D PQCs were observed by SEM. We believe that the MENSL method is a suitable useful tool to realize the PQCs arrays of large area.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.74.1-74.1
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• 2010

Using two-dimensional numerical hydrodynamic simulations, we investigate the regulation of star ormation rates in turbulent, multiphase, galactic gaseous disks. Our simulation domain is xisymmetric, and local in the radial direction and global in the vertical direction. Our models nclude galactic rotation, vertical stratification, self-gravity, heating and cooling, and thermal onduction. Turbulence in our models is driven by momentum feedback from supernova events ccurring in localized dense regions formed by thermal and gravitational instabilities. Self-onsistent radiative heating, representing enhanced/reduced FUV photons from the star formation, s also taken into account. Evolution of our model disks is highly dynamic, but reaches a quasi-teady state. The disks are overall in effective hydrostatic equilibrium with the midplane thermal ressure set by the vertical gravity. The star formation rate is found to be proportional pproximately linearly to the midplane thermal pressure. These results are in good agreement with the predictions of a recent theory by Ostriker, McKee, and Leroy (2010) for the thermal/dynamic equilibrium model of star formation regulation.

• The Mathematical Education
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• v.46 no.3
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• pp.263-272
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• 2007

Mathematics Teaching Efficacy Beliefs Inventory (MTEBI) was translated into Korean and conducted among Korean pre-service mathematics teachers. The Korean-translated MTEBI consists of two subscales with 16 items. Personal Mathematics Teaching Efficacy (PMTE) subscale has 10 items and Mathematics Teaching Outcome Expectancy (MTOE) subscale has 6 items. The purpose of this study is to investigate the internal reliability and the construct validity of the Korean-translated MTEBI. The Cronbach alpha coefficient of Korean-translated MTEBI and its two subscales are respectively .87, .83, and .74 which imply that the instrument is reliable. The construct validity was achieved by performing factor analysis. Principal component solution with varimax rotation for the Korean-translated MTEBI was used in factor analysis and thus the best fit simple structure was obtained by two factors which correspond to the self-efficacy dimension and the outcome expectancy dimension of Bandura's self-efficacy theory.

• The Journal of Information Systems
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• v.32 no.4
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• pp.189-210
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• 2023

Purpose This study aims to investigate factors that positively influence the continuous Artificial Intelligence(AI) Learning Continuity of business major students. Design/methodology/approach To evaluate the impact of AI education, a survey was conducted among 119 business-related majors who completed a software/AI course. Frequency analysis was employed to examine the general characteristics of the sample. Furthermore, factor analysis using Varimax rotation was conducted to validate the derived variables from the survey items, and Cronbach's α coefficient was used to measure the reliability of the variables. Findings Positive correlations were observed between business major students' AI Learning Continuity and their AI Interest, AI Awareness, and Data Analysis Capability related to their majors. Additionally, the study identified that AI Project Awareness and AI Literacy Capability play pivotal roles as mediators in fostering AI Learning Continuity. Students who acquired problem-solving skills and related technologies through AI Projects Awareness showed increased motivation for AI Learning Continuity. Lastly, AI Self-Efficacy significantly influences students' AI Learning Continuity.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.3
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• pp.51-59
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• 2020

PURPOSE: The purpose of this study was to provide clinical basic data to reduce pain and improve function by comparing neck muscle activity and neck alignment using self-stretching and passive stretching exercises for chronic neck pain caused by forward head posture. METHODS: The subjects were divided into 15 subjects assigned to perform self-stretching exercise and 15 subjects assigned to perform passive stretching exercise. The intervention was conducted for a total of 4 weeks. The muscle activity in the neck was measured by surface electromyography (EMG) before intervention, and craniovertebral and cranial rotation angles were measured by X-ray. The 4-week intervention was conducted and the above items re-measured in the same manner and analyzed. RESULTS: Muscle activity within both groups after intervention using self-stretching or passive stretching exercise was significantly different (p < .05)(p < .01). Neck alignment of both groups was significantly different (p < .001)(p < .01). Further, muscle activities of the upper trapezius and splenius capitis muscles showed significant differences (p<.05). Lastly, neck alignment showed statistically significant difference (p < .05). CONCLUSION: Self-stretching exercise activated motor nerves as a posture correction exercise, thereby improving inhibition of muscle activity, muscle contraction delay, and pathological conditions of the muscle. For future research, interventions of self-stretching exercise will be needed for patients with chronic back pain accompanied by forward head posture, and various clinical studies on postural improvement of forward head posture by maintaining a normal muscle tone state are needed.

• Journal of Digital Convergence
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• v.8 no.4
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• pp.123-136
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• 2010

The purpose of this study examines how the self-leadership in organization affects citizenship behavior and which types(transformational leadership, transactional leadership) of leadership can moderate between self-leadership and organizational citizenship behavior. Hypotheses were tested by surveying 255 employees in small and medium enterprises. we conducted exploratory factor analysis for two constructs(behavioral strategy, cognitive strategy) using oblique rotation method that did not assume independence among the factors and main factors of self-leadership were grouped together by two factors. The results of this study are as followings; First, all factors of self-leadership had a significant positive effect on the organizational citizenship behavior. Second, only transformational leadership moderated between cognitive strategy of self-leadership and organizational citizenship behavior.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.179-190
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• 2011

The swirling flow developing in Francis turbine draft tube under part load operation leads to pressure fluctuations usually in the range of 0.2 to 0.4 times the runner rotational frequency resulting from the so-called vortex breakdown. For low cavitation number, the flow features a cavitation vortex rope animated with precession motion. Under given conditions, these pressure fluctuations may lead to undesirable pressure fluctuations in the entire hydraulic system and also produce active power oscillations. For the upper part load range, between 0.7 and 0.85 times the best efficiency discharge, pressure fluctuations may appear in a higher frequency range of 2 to 4 times the runner rotational speed and feature modulations with vortex rope precession. It has been pointed out that for this particular operating point, the vortex rope features elliptical cross section and is animated of a self-rotation. This paper presents an experimental investigation focusing on this peculiar phenomenon, defined as the upper part load vortex rope. The experimental investigation is carried out on a high specific speed Francis turbine scale model installed on a test rig of the EPFL Laboratory for Hydraulic Machines. The selected operating point corresponds to a discharge of 0.83 times the best efficiency discharge. Observations of the cavitation vortex carried out with high speed camera have been recorded and synchronized with pressure fluctuations measurements at the draft tube cone. First, the vortex rope self rotation frequency is evidenced and the related frequency is deduced. Then, the influence of the sigma cavitation number on vortex rope shape and pressure fluctuations is presented. The waterfall diagram of the pressure fluctuations evidences resonance effects with the hydraulic circuit. The influence of outlet bubble cavitation and air injection is also investigated for low cavitation number. The time evolution of the vortex rope volume is compared with pressure fluctuations time evolution using image processing. Finally, the influence of the Froude number on the vortex rope shape and the associated pressure fluctuations is analyzed by varying the rotational speed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.196.2-196.2
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• 2016

The design and development procedures of SF6 gas circuit breakers are still largely based on trial and error through testing although the development costs go higher every year. The computation cannot cover the testing satisfactorily because all the real processes arc not taken into account. But the knowledge of the arc behavior and the prediction of thermal plasmas inside SF6 interrupters by numerical simulations are more useful than those by experiments due to the difficulties to obtain physical quantities experimentally and the reduction of computational costs in recent years. In this paper, in order to get further information into the interruption process of a SF6 self-blast interrupter, which is based on the combination of thermal expansion and arc rotation, gas flow simulations with a CFD-arc modeling are performed during the whole switching process such as high-current period, pre-current zero period, and current-zero period. Through the complete work, the temperature of residual arcs as well as the breakdown index after current zero should be a good criterion to predict the dielectric capability of interrupters.

• Structural Engineering and Mechanics
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• v.55 no.3
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• pp.639-654
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• 2015

Bolted joints are essential elements of mechanical structures and metal constructions. Although their static behaviour is fairly well known, their dynamic behaviour due to shocks and vibrations has been less studied, because of the large size of the finite element models needed for a detailed simulation. This work presents four different simplified models suitable for studying the dynamic behaviour of an elementary bolted joint. Three of them include contact elements to allow sliding of the screw head and the nut on the assembled parts, and the last one allows rotation between screw and nut. A penalty approach based on the Coulomb friction model is used to model contact. The results show that these models effectively represent the dynamic behaviour, with different accuracy depending on the model details. The last model simulates the self loosening of a bolt subjected to transversal vibrations.

• Journal of Korean Physical Therapy Science
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• v.19 no.2
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• pp.35-42
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• 2012

Background : This study was conducted to know the effect of resistance exercise using thera-band in parallel with conservative therapy in patients with frozen shoulder. Methods : We analyze subjective pain scale, ROM and shoulder functional scale 24 patients diagnosed with adhesive capsulitis were included for study. Among them, 12 patients(experiment group) were managed by resistance exercise as well as conservative physical therapy, another 12 patients(control group) were only treated by conservative therapy alone. All the patients were treated three times a week for 4 weeks, and after, and after each treatment subjective pain scale, ROM, shoulder functional score(SFI) were measured. Results : The VAS were significant reduced between experimental group and control group according to pre-treatment and post-treatment. In experimental group, the ROM and SFI has increased than control group according to pre-treatment and post-treatment. Conclusion : According to the results, we concluded that both conservative therapy and self resistance exercise using thera-band technique are more effective for increasing ROM especially flexion, abduction, internal rotation and SFI than conservative therapy alone.