• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.201-202
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• 2006

An apparatus measuring changes of various forces directly and continuously was developed by a way of direct touch between powders and transmitting force component, which can be used to study forces state of powders during warm compaction. Using the apparatus, warm compaction processes of iron-based powder materials containing different lubricants at different temperatures were studied. Results show that densification of the iron-based powder materials can be divided into four stages, in which powder movement changes from robustness to weakness, while its degree of plastic deformation changes from weakness to robustness.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.1
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• pp.9-14
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• 2009

Purpose : The purpose of this study is change of lumbar multifidus muslce recorded simultaneously by ultrasound imaging during upper extremity functional movement in chronic low back pain patients. The subject were consisted of 10 women patients with chronic low back pain and healthy asymptomatic subject 10 women. Methods : 10 women patients with chronic low back pain and healthy asymptomatic subject 10 women is voluntary participated for the research. Subjects were positioned in standing. Multifidus size were measured from L4 vertebral segement. The ultrasound imaging apparatus(Sonoace 6000, Medison, Korea) was epuipped with a 5-MHz convex array transducer. The upper extremity lifting movement used to activate the multifidus was then measured. Results : Results of the analysis showed that at the L4 vertebral leves, healthy asymptomatic subjects had significantly larger multifidus muscle compared with chronic LBP subjects. Conclusion : This study will be used as treatment method of patient with chronic LBP. The multifidus muscle in chronic LBP patients clinical significance. Most of chronic LBP patients have multifidus contraction pattern. Especially multifidus contraction in L4 vertebral segement. So chronic LBP patients necessary multifidus muscle release treatment.

• The korean journal of orthodontics
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• v.24 no.4 s.47
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• pp.897-916
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• 1994

The biologic potential, which is different from the piezoelectric signals, relates tooth movement at least in part to changes in bone metaboliosm in bioelectric theory. The purpose of this experiment was to determine wheather the application of half sine-wave pulsed electromagnetic fields (HSPEMF) could increase both the rate and amount of orthodontic tooth movement. Forty-three male Hartley guinea pigs, weighting approximately 255g, were utilized in this study. The animals were 35 days old at the start of the study. Laterally directed orthodontic force was applied to the maxillary central incisors of 40 Hartley guinea pigs (20 experimental, 20 control). According to the amount of orthodontic force (6g, 12g), they were divided into two sub-groups (10 experimental I, 10 experimental II, 10 control I, 10 control II). During the experimental period, experimental animals were placed in plastic animal holders with their heads positioned in an area of uniform electromagnetic field. Control animals were placed in similar plastic holders that did not carry the electric apparatus. The results were as follows : 1. The application of a HSPEMF to the experimental groups significantly increase the final amount of orthodontic tooth movement observed over a 10-day experimental period. 2. The application of a HSPEMF to the experimental groups significantly increase the velocity of orthodontic tooth movement observed over a 10-day experimental period. 3. There was no significant difference in the final amount of orthodontic tooth movement at the fourth day to the eighth day, but there was significant difference in the final amount of orthodontic tooth movement at the nineth, tenth day during a 10-day experimental period. 4. After 10 days of HSPEMF exposure & orthodontic force, the experimental groups demonstrated more osteodasts in the pressure side than control groups.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.786-791
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• 2000

The purpose of this study is to investigate quantitatively the effects of drawbead dimensions to the weld line movements for the deep drawing of the tailor welded blanks. Square blanks have been used and five different circular drawbeads were installed in experimental apparatus. The differences in the weld-line movements and the tendencies of the strain distributions in thickness were investigated by experimental and analytical methods. The results of the weldline movement show that the smaller the radius of drawbead installed, the larger the values of movements. Also it is shown for thickness strain in central and diagonal direction that the larger the dimension of drawbead, the larger the values of maximum thickness strain. The drawbead adds the additional restraining forces to the blank, hence the movement of weld line could be controlled by the adequate drawbead installation

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.19-25
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• 1999

This paper addresses a development work of a SLA apparatus on laboratory basis. The SLA test machine is composed of optical, movement, curing and control subsystems. Optical part is performed by a He-Cd laser with mirror combination and mechanical movement is achieved by X-Y table. The developed system is evaluated by several test runs, and shows a good precision capability in forming a basic part. The technique used in this work can be extended to replace the high technology transfer cost of commercial RP machine.

• Journal of Astronomy and Space Sciences
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• v.34 no.2
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• pp.171-182
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• 2017

In this study, the internal structure of a Heumgyeonggak-nu (欽敬閣漏) was designed, and the power transmission mechanism was analyzed. Heumgyeonggak-nu is an automated water clock from the Joseon Dynasty that was installed within Heumgyeonggak (欽敬閣), and it was manufactured in the $20^{th}$ year of the reign of King Sejong (1438). As descriptions of Heumgyeonggak-nu in ancient literature have mostly focused on its external shape, the study of its internal mechanism has been difficult. A detailed analysis of the literature record on Heumgyeonggak-nu (e.g., The Annals of the Joseon Dynasty) indicates that Heumgyeonggak-nu had a three-stage water clock, included a waterfall or tilting vessel (欹器) using the overflowed water, and displayed the time using a ball. In this study, the Cheonhyeong apparatus, water wheel, scoop, and various mechanism wheels were designed so that 16 fixed-type scoops could operate at a constant speed for the water wheel with a diameter of 100 cm. As the scoop can contain 1.25 l of water and the water wheel rotates 61 times a day, a total of 1,220 l of water is required. Also, the power gear wheel was designed as a 366-tooth gear, which supported the operation of the time signal gear wheel. To implement the movement of stars on the celestial sphere, the rotation ratio of the celestial gear wheel to the diurnal motion gear ring was set to 366:365. In addition, to operate the sun movement apparatus on the ecliptic, a gear device was installed on the South Pole axis. It is expected that the results of this study can be used for the manufacture and restoration of the operation model of Heumgyeonggak-nu.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.591-597
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• 1996

To straighten the path that farm machinery follows in paddy fields, it is necessary to measure and evaluate the tracks that these machines leave behind. However, there are no known methods for making such measurements and evaluations since it is difficult to accurately trace the paths that the machine make in paddy fields. Therefore, a measuring system has been developed which can accurately recored the path of a farm machinery in a field by measuring the horizontal straight-line distance from the side of the field to the machine. This system consists of a track subsystem on the machine and a range finder system. A measuring appraratus is installed on a flatcar which runs on rails over 50 m long at the side of the filed. The track subsystem uses a CCD camera to track the movement of the machine in the field which is following a lengthwise path. The range finder subsystem measures the distance that the measuring apparatus has traveled on the rails and the distance from the app ratus to the machine in the field. This system makes it possible to record the path that the machine travels. Even though differences in traveling distance arise between the measuring apparatus and the farm machine, these differences are detected by image processing , which allows the machine in the field to be located accurately. The short(0.05 second) time required for image processing is enough to follow an object . In the present study, this system was able to measure the path that a moving tractor makes. Even though a lag of up to 0.4 meters occurred, this system did not miss its target during operation of the track subsystem. Thus the path measuring system developed here is able to record vehicle paths automatically by following the movement of vehicles in the field and measuring the distance to them. It is expected to come into use in such applications as unmanned moving vehicle tests.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.529-543
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• 2003

Real-time measurements of skin movement induced by air blown on the surface was measured with time. We investigated age-related changes in displacement of the skin surface on the face or the inner upper arm caused by air on 98 Japanese women volunteers aged from 10 to 70 years old. The maximum distance (the denting state) that the skin moved reached 2-5 mm within 10-15 msec on the cheek skin. After that, the skin generally recovered to the original state within 40-50 msec. The maximum speed of movement was 0.5 m/sec and the recovery speed was about 0.25 m/sec on the cheek skin. Significant changes with age were not observed in the denting state, but a significant correlation with age was observed in the recovery state. For example, the maximum recovery speed decreased significantly with age (p=-0.568, p<0.001) and the time required for recovery increased significantly with age (p=0.561, p<0.001). Although the inner upper arm also showed similar results to a cheek, a few parameters were different. This apparatus is a more practical macroscopic system for evaluating skin mechanical properties without contact. This apparatus is effective not only for measuring the mechanical properties of facial skin but also of body skin, such as swelling or sagging of body parts.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1366-1369
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• 2010

Along with the increasing need of sea development, the hydraulic stability of seabed structure on a soft seafloor ground is becoming an issue in the course of seaside development recently. However, the movement and hydraulic resistance or hydraulic stability of seafloor ground are mutually coupled with various phenomena, and there has been no clear proof for the issue, which makes it difficult to forecast. Furthermore, most researches are focused on hydraulic variables and the conditions of marine external force, while there have been few researches into the assessment in consideration of the type of a seafloor ground and the geotechnical characteristics. In addition, according to the periodic change of the flow direction, possible changes in hydraulic resistance performance of the seafloor deserves all the recognition. But there is no way to measure the hydraulic unstability of the sea ground due to tidal flow quantitatively. In this study, conventional hydraulic resistance measurement apparatus was improved to consider direction change of the current flow. Various artificial clayey soil specimens were made from Kaolinite and Jumunjin standard sand and hydraulic resistance tests were performed by changing the flow direction to validate the effect of the direction change on the scour of the seafloor.

• The korean journal of orthodontics
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• v.19 no.2
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• pp.37-55
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• 1989

The tissue reactions concerned in alveolar bone remodelling at the pressure zones of rat molar periodontium associated with the application of force (15 gm) to the maxillary first molar teeth of the albino rats were studied by the transmission electron microscopy. Osteoclasts referrable to bone resorption were observed thereafter 3 hour survival period and undermining resorption was generated thenceforth 2 day survival period. Bone resorption, reversal zone and new bone formation were simultaneously observed adjacent to the zone of undermining resorption in the 7 day survival period. Osteoclasts with well developed primary lysosome, ruffled border, clear zone, granules and Golgi apparatus were detected at the zone of the bone resorption, and dark and bright cells adjacent to the osteoclasts as well. Mononuclear cells and perpendicularly arranged collagenous fibers were observed in the reversal zone and, on the other hand, osteoblasts with well developed Golgi apparatus and rough endoplasmic reticulum were detected at the zone of bone formation.