• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.230-237
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• 2024

Dispersion munitions are often equipped with dispersive submunitions used to scatter bombs over a wide area, and one of the types of dispersive submunitions is the Magnus rotor, commonly referred to as a self-rotating flying body. The Magnus rotor is designed to be dispered over a wide area by utilizing the principle of the Magnus effect through self-rotation, and has various trajectories depending on the initial conditions from the mother dispersion munition. In this paper, an index to evaluate the dispersion uniformity of footprint of the dispersive submunition is presented and the dispersion uniformity according to various initial release conditions is evaluated, and it is getting larger with high incidence angle and get max value at certain initial angular velocity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.108-117
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• 2024

In this study, simulations based on computational fluid dynamics were performed for self-propulsion performance prediction of a catamaran that has asymmetrical inside and outside hull form and numerous knuckle lines. In the simulations, the Moving Reference Frame (MRF) or Sliding Mesh (SDM) techniques were used, and the rotation angle of the propeller per time step was different to identify the difference using the analysis technique and condition. The propeller rotation angle used in the MRF technique was 1˚ and those used in the SDM technique were 1˚, 5˚, or 10˚. The torque of the propeller was similar in both the techniques; however, the thrust and resistance of the hull were computed lower when the SDM technique was applied than when the MRF technique was applied, and higher as the rotation angle of the propeller per time step in the SDM technique was smaller in the simulations for several revolutions of the propeller to estimate the self-propulsion condition. The revolutions, thrust, and torque of the propeller in the self-propulsion condition obtained using linear interpolation and the delivered power, wake fraction, thrust deduction factor, and revolutions of the propeller obtained using the full-scale prediction method showed the same trend for both the techniques; however, most of the self-propulsion efficiency showed the opposite trend for these techniques. The accuracy of the propeller wake was low in the simulations when the MRF technique was applied, and slight difference existed in the expression of the wake according to the rotation angle of the propeller per time step when the SDM technique was applied.

• Journal of Korean Academy of Nursing
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• v.47 no.4
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• pp.551-561
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• 2017

Purpose: This study aimed to present and test a structural model for describing and predicting the factors affecting subjective career satisfaction of nurses experiencing rotation and to develop human resources management strategies for promoting their career satisfaction related to rotation. Methods: In this cross-sectional study, we recruited 233 nurses by convenience sampling who had over 1 year of career experience and who had experienced rotation at least once at G university hospital. Data were collected from August to September in 2016 using self-reported questionnaires. The exogenous variables consisted of rotation perception and rotation stress. Endogenous variables consisted of career growth opportunity, work engagement, and subjective career satisfaction. A hypothetical model was tested by asymptotically distribution-free estimates, and model goodness of fit was examined using absolute fit, incremental fit measures. Results: The final model was approved and had suitable fit. We found that subjective career satisfaction was directly affected by rotation stress (${\beta}=.20$, p=.019) and work engagement (${\beta}=.58$, p<.001), indirectly affected by rotation perception (${\beta}=.43$, p<.001) through career growth opportunity and work engagement. However, there was no total effect of rotation stress on subjective career satisfaction (${\beta}=-.09$, p=.270). Career growth opportunity directly and indirectly affected subjective career satisfaction (${\beta}=.29$, p<.001; ${\beta}=.28$, p<.001). These variables accounted for 65% of subjective career satisfaction. Conclusion: The results of this study suggest that it is necessary to establish systematic and planned criteria for rotation so that nurses can grow and develop through sustained work and become satisfied with their career.

• Journal of Korean Academy of Nursing Administration
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• v.7 no.1
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• pp.127-144
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• 2001

The purpose of this study is to provided a basic administrative data for effective personnel management of nurses' by investigation their assessment and satisfaction with the job rotation and by analyzing the relation between their satisfaction and organizational commitment. Data were collected from Nov. 20 to Nov. 25, 2000 through self-reporting questionnaires taken by 280 nurses working at a university hospitals The 3 structured instruments were used for collecting the data; Questionnaires for measuring the utility and the problem of job rotation, Questionaires for measuring the satisfaction with the job rotation, and Mowday's Organizational Commitment Questionnaires. The data obtained were analyzed using frequency, percentage, average, standard deviation, range, Cronbach's alpha coefficients, Peason's correlation coefficients, t-test, one-way ANOVA, and chi-square test, multiple regression. The Results were as follows : 1. The supporters for regular job rotation account for 67% while the opponents to it account for 33%. The chief reason for endorsing the regular job rotation is quoted ${\lceil}$to attain more diverse job experiences${\rfloor}$, followed in order by ${\lceil}$to improve the job motivation and morale through the realization of personal needs${\rfloor}$, ${\lceil}$to place the right man in the right position${\rfloor}$. The reasons for opposing to the regular job rotation were listed in order ${\lceil}$difficulties to secure the expertise of nursing${\rfloor}$, ${\lceil}$personal needs not fully reflected in the job rotation${\rfloor}$, ${\lceil}$job rotations prompted rather by the administrative needs than by personal aptitude and ability${\rfloor}$. 2. In the assessment of job rotation, the points affirming the utility of the job rotation are $2.60({\pm}.66)$ out of possible 5 points and those admitting the problems the job rotation are $3.58({\pm}.59)$. The satisfaction with the job rotation is rated at $2.98({\pm}.55)$. 3. In the analysis into the relation between the assessment of job rotation and satisfaction with the job rotation, fairly high positive correlation is revealed between the satisfaction and utility of job rotation, whereas, considerably high negative correlation is seen between the satisfaction and problems with the job rotation(p=.000). 4. There is relatively high positive correlation between the satisfaction with the job rotation and organizational commitment(p=.000). In conclusion, the utility of on the job rotation and their satisfaction with the job rotation have positive correlation and the satisfaction with the job rotation and organizational commitment showed the positive correlation, too. Therefore, it is thought desirable to take administrative strategies well as education to improve the recognition of the job rotation's utility and to reduce the recognition of the problems with the job rotation to remain in the direction toward contributing to enhancement of the organizational commitment.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.239-244
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• 2011

Nano Imprint Lithography(NIL) is technique for copying a pattern from stamp with nano size pattern in order to replicated the materials. It is very important to demold in order to make NIL process effectively. Self Assembled Monolayers(SAM) coater is manufactured by means of decreasing surface energy with the stamp surface treatment to improve release characteristics. Manufactured device contains tilting and rotation option for increasing process life time by coating on the sidewall of the pattern in stamp. The stamp coated with optimized tilting angle $30^{\circ}$ and rotation speed of 10rpm has more imprinting cycles than the stamping coated without tilting and rotation. Effective SAM coating on the sidewall of the pattern in stamp will improve by 50% of process life time.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.24 no.2
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• pp.37-42
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• 2018

Background: The Purpose of this study was to evaluate the value of Spencer technique on the range of motion (ROM), Pain, function in patients with shoulder adhesive capsulitis. Methods: subjects consisted of 30patients who were diagnosed shoulder adhesive capsulitis. All subjects are randomly assigned to 2groups: Spencer technique (ST) group (n=15), self assistive ROM exercise(S-A ROM E) group (n=15). The subjects performed an intervention program 30 minuets per day and was repeated 3 times a week for 4 weeks a total of 12 times. ROM of flexion, abduction, external rotation, internal rotation were measured using a goniometer. The visual analog scale (VAS), Shoulder pain and disability index (SPADI) were used to measure pain, functional ability. Results: In the intergroup comparisons after the intervention, ROM of flexion, abduction, internal rotation, VAS, SPADI were significantly different(p<.05). Spencer technique was more effective for improving ROM, pain, functional ability than self assistive ROM exercise. Conclusions: Our study suggest that considering Spencer technique for the patient with shoulder adhesive capsulitis. Further studies on Spencer technique are needed in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.423-430
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• 2017

This study examined the effects of role rotation experience on learning flow, self leadership and debriefing satisfaction in nursing students. A non-equivalence control group quasi-experimental study was used and included as participants 203 junior nursing students at Y University. The experimental group (n=103) participated in the teaching class using a role rotation experience, while the control group (n=100) received conventional practice education. The outcome measurements were learning flow, self leadership, and debriefing satisfaction. The collected data were analyzed using a chi-test, and at-test using the SPSS WIN 21.0 program. The total score of learning flow and self leadership were similar in the two groups. On the other hand, in the case of the debriefing satisfaction (t=-2.70, p=.008), the experimental group ($4.24{\pm}0.51$) was remarkably higher than the control group ($4.03{\pm}0.60$). Although the changes regarding the learning flow and self leadership could not be identified, the debriefing satisfaction had been affected by the practice education using the role rotation experience. Therefore, to identify the effects of simulation education for further details, more research with diversified subjects and varied durations is needed.

• The Journal of Korean Physical Therapy
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• v.31 no.5
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• pp.266-272
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• 2019

Purpose: This study compared the effects of Static stretching and Mulligan's Two-leg rotation about the Hamstring flexibility, Hip range of motion, and pain. Methods: The subjects were allocated randomly into two groups: Static stretching group (n=13) and Mulligan's two leg rotation group (n=14). The study was designed with stretching protocols for four minutes and thirty seconds per day five times a week for three weeks in total. Measurements, including the Sit and reach test, Active/Passive Straight leg raise, and Visual analogue scale, were conducted before and after the intervention. The data were analyzed using a paired t-test and independent t-test. Results: The flexibility of the two leg rotation group was higher than the static stretching group after the intervention. The post-sit and reach test value of the two leg rotation group was significantly higher than the pre-sit and reach test value of the static stretching group. In addition, the variance of the sit and reach test of the two leg rotation group was significantly higher than that of the static stretching group. Conclusion: These results showed that two leg rotation techniques have a positive effect on the changes in the sit and reach test and active straight leg raise test. Two leg rotation techniques can be recommended as a self-stretching and easier way to stabilize the lumbopelvic rhythm, reduce the stiffness of the muscle and relieve pain. This is effective in preventing muscle damage, enabling muscle relaxation and reducing the risk of injury to the spine during daily lives and in sports activities.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.66.1-66.1
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• 2010

Using two-dimensional numerical hydrodynamic simulations, we investigate the star formation rate (SFR) in turbulent, multiphase, galactic gaseous disks. Our simulation domain is axisymmetric, and local in the radial direction and global in the vertical direction. Our models include galactic rotation, vertical density stratification, self-gravity, radiative heating and cooling, and thermal conduction, but do not include spiral-arm features. Turbulence in our models is driven by momentum feedback from supernova explosion events occurring in localized dense regions formed by thermal and gravitational instabilities. Self-consistent radiative heating, representing enhanced/reduced FUV photons from the star formation, is also taken into account. By controlling three parameters (the gas surface density, the stellar disk density, and the angular rotation rate) that characterize local galactic disks, we explore how the SFR depends on the background environmental state. We also discuss the relation between the SFR and the gas surface density found in our numerical models in comparison with observations.

• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.243-248
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• 2004

Disk galaxies abound with intermediate-scale structures such as OB star complexes, giant clouds, and dust spurs in a close geometrical association with spiral arms. Various mechanisms have been proposed as candidates for their origin, but a comprehensive theory should encompass fundamental physical agents such as self-gravity, magnetic fields, galactic differential rotation, and spiral arms, all of which are known to exist in disk galaxies. Recent numerical simulations incorporating all these physical processes show that magneto-Jeans instability (MJI), in which magnetic tension resists the stabilizing Coriolis force of galaxy rotation, is much more powerful than swing-amplification or the Parker instability in forming self-gravitating intermediate-scale structures. The MJI occurring in shearing and expanding flows off spiral arms rapidly forms structures elongated along the direction perpendicular to the arms, remarkably similar to dust spurs seen in HST images of spiral galaxies. In highly nonlinear stages, these spurs fragment to form bound clumps, possibly evolving into bright arm and interarm H II regions, suggesting that all these intermediate-scale structures in spiral galaxies probably share a common dynamical origin.