• Imaging Science in Dentistry
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• v.52 no.4
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• pp.409-413
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• 2022

This report presents a rare case where a displaced temporomandibular joint (TMJ) disc was reduced to its normal position after orthognathic surgery, and long-term magnetic resonance imaging (MRI) follow-up visualized these postoperative changes. A 22-year-old male patient presented for facial asymmetry. He also complained of pain in the right TMJ area, and MRI showed disc displacements in both TMJs. After orthognathic surgery for facial asymmetry correction, the TMJ was re-evaluated. The symptom had resolved and the disc was positioned within the normal range during mouth opening. However, 6 and a half years after surgery, he complained of recurrent pain in the right joint, and MRI revealed medial disc displacement in the right TMJ. In conclusion, the influence of orthognathic surgery on the disc position might continue for a long time until the TMJ adapts to the new position. Careful and long-term follow-up is suggested to assess the TMJ complex.

• Journal of Power Electronics
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• v.10 no.4
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• pp.405-411
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• 2010

This paper proposes a novel tracking algorithm considering radiation to improve the power of a photovoltaic (PV) tracking system. The sensor method used in a conventional PV plant is unable to track the sun's exact position when the intensity of solar radiation is low. It also has the problem of malfunctions in the tracking system due to rapid changes in the climate. The program method generates power loss due to unnecessary operation of the tracking system because it is not adapted to various weather conditions. This tracking system does not increase the power above that of a power of tracking system fixed at a specific position due to these problems. To reduce the power loss, this paper proposes a novel control algorithm for a tracking system and proves the validity of the proposed control algorithm through a comparison with the conventional PV tracking method.

• Korean Journal of Oriental Medicine
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• v.17 no.2
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• pp.85-100
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• 2011

Objectives : This study aimed to investigate the effect of four common types of Qigong position (standing, sitting, supine, and horse-riding position) on the autonomic nervous system. Method : Thirty healthy subjects participated in this study once a week for four weeks. Heart Rate Variability (HRV) was measured three times (before, during, and after the position) while the subject maintained one of four positions for ten minutes. Result : There were significant changes HRV in the standing position. In the sitting position, both the sympathetic and parasympathetic nerves were activated. On the other hand, in the spine position, heart rate (HR) was decreased. Activation of sympathetic and parasympathetic nerves was also observed in this position. Significant increases of indices related to awakening and concentration were observed accompanied by increase of HR and a sympathetic nerve was activated in the riding-horse position. Conclusions : In the present study, it was shown that each Qigong position caused various and significant changes in autonomic nervous system. It would be expected that these results can be applied to choose appropriate Qigong position according to objective of Qigong therapy although it is remained to further evaluate the effects of long-term maintenance of Qigong positions and repeated Qigong training.

• Korean Journal of Oriental Medicine
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• v.16 no.1
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• pp.157-171
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• 2010

This study aimed to investigate the effect of four common types of Qigong position (standing, sitting, supine, and horse-riding position) on the autonomic nervous system. Thirty healthy subjects participated in this study once a week for four weeks. Electroencephalogram (EEG) was measured three times (before, during, and after the position) while the subject maintained one of four positions for ten minutes. There were significant changes in HRV components compared with EEG power spectra in the standing position. Especially, the ratio of low-to-high frequency (LF/HF) which represents a state of balance of autonomic nervous system was increased. In the sitting position, $\beta$ wave which reflects a state of alert consciousness was increased and both the sympathetic and parasympathetic nerves were activated. On the other hand, in the spine position, $\theta$ wave which signifies a state of relaxation was increased and heart rate (HR) was decreased. Activation of sympathetic and parasympathetic nerves was also observed in this position. Significant increases of indices related to awakening and concentration were observed accompanied by increase of HR and a sympathetic nerve was activated in the riding-horse position. In the present study, it was shown that each Qigong position caused various and significant changes in autonomic nervous system. It would be expected that these results can be applied in the choice of appropriate Qigong position according to objective of Qigong therapy although it is remained to further evaluate the effects of long-term maintenance of Qigong positions and repeated Qigong training.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.627-641
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• 2022

This study aims to help elementary school teachers increase their knowledge about the changes in the positions of the sun and moon during the day and the first time the moon observation begins in the Earth and Space section of the Earth and the Moon. The survey questions were grouped into four categories, namely, textbook explanation, inquiry activities, achievement of learning goals, and other opinions. The perception of each question differed according to advanced science majors and teaching careers and experiences of this unit. In addition, understanding the diverse views of the participants using descriptive questions was possible. The study recruited 67 teachers working at an elementary school in Gyeonggi-do. The conclusion is as follows. First, the teachers exhibited similar positive and negative perceptions about the description of the textbook on the changes in the positions of the sun and moon during the day. Second, the study found that majority of teachers used alternative methods when guiding students regarding the change in the positions. This trend was not correlated with the sun and the moon, and the study observed no difference in advanced majors and teaching careers and experience of this unit. Third, the majority of teachers responded that they could achieve their learning goals through this learning. However, many teachers complained of various difficulties in guiding students about the lesson, and the majority alternative methods. The results demonstrated the perception of teachers that students can achieve learning goals through alternative methods without direct observation.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1310-1317
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• 2014

In our daily life, the need of energy increases day by day. However, the amount of natural resources on the earth is limited and thus gaining renewable energy as an energy resource is one of the important and urgent problems. Solar energy is one of the most popular available energy sources that can be converted into electricity by using solar panels. In order for solar panels to produce maximal output power, the incident angle of the sunlight needs to be persistently perpendicular to the solar panel. By the way, most of the solar panels are installed at fixed position and direction. Therefore, as the sun's position changes, it is impossible to produce maximal output power inevitably. To improve this problem, in this paper, a sun tracking system using two degree-of-freedom (DOF) active sensor array is proposed so that the solar panel may always direct sunlight perpendicularly. And also a series of software, such as a search mode and a holding mode, which can control the developed sun tracking system is developed. Several experiments using the implemented sun tracking system are executed and the effectiveness of the system is verified from the experimental results.

• The Journal of Advanced Prosthodontics
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• v.1 no.3
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• pp.118-123
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• 2009

STATEMENT OF PROBLEM. Proper proximal contact is important for maintaining and stabilizing the dental arch. However, the proximal contact strength (PCS) is not a constant value and can be affected by a variety of factors. PURPOSE. This study examined the influences of postural changes on the posterior PCS. MATERIAL AND METHODS. Twelve adults with a normal occlusion and had not undergone prosthetic treatment or proximal restoration were participated in this study. A metal strip was inserted into the proximal surface and removed at a constant velocity. The contact strength was measured in every contact point between canine to second molar in both arches. The PCSs were obtained initially in the upright position, secondly in the supine position and finally in the upright position again. All measurements were repeated after a 2 hour period. Statistical analysis was carried out using the Friedman test (P < .05). RESULTS. Generally, a decrease in PCS occurred when the posture was changed from the initial upright to supine position, while it increased when the posture was changed from the supine to upright position. A significant change was observed in all areas except for between the canine-first premolar in the maxilla and between the first molar-second molar in the mandible areas. CONCLUSION. The posterior PCS, which dentists generally believe to be a static feature of occlusion, is affected significantly by posture.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1092-1099
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• 2011

This paper is concerned with the ATO speed profile generation method in the moving block system. The ATO speed profile is calculated using the acceleration limit and the jerk limit to improve ride comfort. In addition, the speed limit and stop distance provided from ATP profile should be considered to ensure safety. In the moving block system, the speed limit and the stop position are frequently changed in real-time. Therefore, the ATO speed profile should be regenerated immediately according to change of the speed limit and the stop position, within the acceleration limit and the jerk limit. In this paper, the ATO speed profile generation method is proposed, which considers not only frequent changes of the speed limit and the stop position but also acceleration limit and jerk limit. Futhermore the simulation result is presented to verify usefulness of this method.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.37
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• pp.36.1-36.7
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• 2015

Background: This study was performed to evaluate three-dimensional positional change of the condyle using three-dimensional computed tomography (3D-CT) following unilateral sagittal split ramus osteotomy (USSRO) in patients with mandibular prognathism. Methods: This study examined two patients exhibiting skeletal class III malocclusion with facial asymmetry who underwent USSRO for a mandibular setback. 3D-CT was performed before surgery, immediately after surgery, and 6 months postoperatively. After creating 3D-CT images by using the In-vivo $5^{TM}$ program, the axial plane, coronal plane, and sagittal plane were configured. Three-dimensional positional changes from each plane to the condyle, axial condylar head axis angle (AHA), axial condylar head position (AHP), frontal condylar head axis angle (FHA), frontal condylar head position (FHP), sagittal condylar head axis angle (SHA), and sagittal condylar head position (SHP) of the two patients were measured before surgery, immediately after surgery, and 6 months postoperatively. Results: In the first patient, medial rotation of the operated condyle in AHA and anterior rotation in SHA were observed. There were no significant changes after surgery in AHP, FHP, and SHP after surgery. In the second patient, medial rotation of the operated condyle in AHA and lateral rotation of the operated condyle in FHA were observed. There were no significant changes in AHP, FHP, and SHP postoperatively. This indicates that in USSRO, postoperative movement of the condylar head is insignificant; however, medial rotation of the condylar head is possible. Although three-dimensional changes were observed, these were not clinically significant. Conclusions: The results of this study suggest that although three-dimensional changes in condylar head position are observed in patients post SSRO, there are no significant changes that would clinically affect the patient.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.215-224
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• 2009

Analysis for various driven nozzle position changes. The analysis was done for different Reynolds number in entrance region of jet-pump and for several diameter ratios of driven nozzle. (1) The largest absorption energy was found at the point s=1 in condition of diameter ratio 1:3.21 and point s=0.5 in condition of diameter ratio 1:2.25. (2) The absorption energy was not related to the change of entrance velocity and the driven nozzle position having the largest absorption energy was function for cross section ratio. (3) As the position of driven nozzle moves to the downstream, the absorption energy gets weaker. Because the energy from swirl was lost at the cross section gets smaller. (4) As the position of driven nozzle moves to the downstream, the injection energy leans to the upper direction wall and as the Reynolds number increase, the lean phenomenon is more distinct. (5) The flow quantity of driven nozzle, the diameter ratio 1:3.21, was 32% higher than that of 1 : 2.25 and as the inlet velocity gets faster the efficiency decreased. And as the cross section of the driven nozzle increases.