• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.1-5
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• 2011

Electronics in modern life have become more miniaturized and precise and new technology of electronic components has made these trends possible. The explosive demand of electronic components needs more high-speed and accurate performance of manufacturing processes. For high-speed actuation, solenoids, voice coil motors and piezo motors have been used. A solenoid actuator characterized by low price, available small size, and convenience is one of the main components of production equipments requiring compact and high-speed actuators. Since these actuators show millisecond order responsiveness, the improvement of 1~2msec is very important in industrial applications. In this paper, the mathematical model of the solenoid is formulated and simulated using SIMULINK$^{(R)}$. To verify the model, the responses for step input with open-loop control is obtained and compared with the simulation result. In order to improve the responsiveness, Hold voltage method is introduced and optimal value between spring constant and hold voltage is suggested.

• The korean journal of orthodontics
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• v.4 no.1
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• pp.57-61
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• 1974

The patient, a girl of 19 years in good health, had a class I malocclusion. The maxillary left centra1 incisors and both lateral incisors had already erupted. But the space for the right central incisor was partially closed by the mesial drifting of the neighboring teeth. The caused a shift in the midline and a cross-bite relation on the incisors. X-ray examination revealed the presence of the right central incisor in the alveolar bone and odontoma just above the crown of the right central incisor. After enough space for the impacted incisor was created in the dental arch with a open-coil spring the rectangular incision was made. Removing the odontoma uncovered the flat surface of the labial aspect of the incisor. During the tooth had erupted of its own accord, any unnecessary force had been imposed on the tooth. When it was decided that the tooth should be brought out by the mechanical device, the gold cast onlay with hook was used and run a light elastic between this hook and the main arch wire. Finally the tooth was brought down to the arch level. The result was excellent. Fortunately the esthetic problem and any detrimental effects on the psychological make-up could be avoided.

• The korean journal of orthodontics
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• v.23 no.1 s.40
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• pp.89-100
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• 1993

The purpose of this study was to evaluate the effect of orthodontic force on periodontal cellular activity by immunoperoxidase stain of epidermal growth factor, one of the tissue hormone. And supplementarily, to investigate of the changes of periodontal structures, periodontium was stained by H-E, Masson's Trichrome, P. A. S. stain after orthodontic force application. The experimental animals were four young adult dogs of average 8 month old. The fixed orthodontic appliance was cemented on mandibular right 4th premolar and 1st molar of each animal as experimental site. Mandibular left 4th premolar area of the same animal was used as control. The appliance consist of two silver crown soldered with 0.030' tube, $0.018\times0.022'$ S.S. sectional arch wire, and 0.009' open coil spring for manifestating of orthodontic force for bodily tooth movement of mandibular 4th premolar toward mesial direction. Experimental group was sacrificed at 1, 2, 3, 5 weeks from beginning of the experiment, and was investigated immunohistochemically and bistochemically by several staining methods. Findings were as follows: 1. The degree of EGF staining in control group was highest in epithelium of periodontium, and osteoclasts, osteoblasts and fibroblasts around the capillary were stained at higher level in periodontium. Generally, control group shows positive distribution of EGF all around the periodontal area. 2. The degree of EGF staining in control and 5 week group were similar, and did not show the significant different level between tension and pressure side. 3. All of 1, 2, 3 week group showed the same staining degree and distribution of EGF, and the tension side was more positive reaction of EGF stain than the pressure side. 4. The features of collagen fiber and periodontal fiber arrangement observed by H-E, Masson's Trichrome and P. A. S. stain revealed that oblique periodontal fibers were strectched in tension side, compressed in pressure side of all experimental group. Some fiber group in pressure side of 5 week group recovered the regular arrangement along the capillaries.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.359-371
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• 1996

The purpose of this study was to investigate the changes about the cellular activity on DNA synthesis in the periodontal ligament of dog, in which experimental tooth movement was performed. A control and 5 experimental dogs, one and half year in age, were studied. Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars ; heavy force (250-300g), between right mandibular premolars. Experimental dogs were sacrificed after infusion of bromodeoxyuridine(BrdU), at 12 hours, 1, 3, 7 and 14 days after force application, respectively. And the histologic and the immunohistochemical evaluation were performed on the obtained periodontal tissue around mandibular premolars, using anti-romodeoxyuridine antibody, which can indicate proliferating cells. The results were as follows: 1. The tearing of periodontal ligament and the vascular dilatation at tension side were observed in 12 hours, increasing until 3 days. After then it decreased; Such a finding was more evident in heavy force group than in light force group. 2. The hyalinization of the periodontal ligament and the activity of osteoclast at pressure side were observed in 12 hours, increasing until 3 days. But from 7 days on, it decreased; Such a finding was more evident in heavy force group than in light force group. 3. The BrdU expression in the control group was positive, mainly in the oral epithelium and the fibroblasts in the periodontal ligament, but negative in bone cells in periodontal ligament. 4. The BrdU expression in the experimental group was more positive in tension side than in pressure side; The expression was a little more positive in the periapical area than in the cervical area of tooth. 5. The BrdU expression in light force group was the highest in 1 day, after which it decreased; In heavy force group, it was the highest in 12 hours, after which it decreased. But in 14 days, there was no difference between the experimental group and control group.

• The korean journal of orthodontics
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• v.25 no.4
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• pp.433-445
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• 1995

Tooth movement, the phenomena and mechanisms of which are still controversial, can be considered as part of the result of the inflammatory processes. The purpose of this study was to examine the activity of macrophage and T-cell, playing important roles in the immune reaction, in the periodontal ligament of dog, in which experimental tooth movement was performed. Six one and half year-old dogs, a control and 5 experimentals, were studied. Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars ; heavy force (250-300g), between right mandibular premolars. Experimental dogs were sacrificed at 12 hours, 1, 3, 7 and 14 days since force application, respectively. And the histologic and the immunohistochemical evaluation on the obtained tissue were performed, using $\alpha$-1-antichymotrypsin and CD3 antibodies. The results were as follows : 1. There were more inflammatory cell infiltrations in heavy force group than in light force group until 3 days. But from 7 dsays on, no difference was not observed between groups ; Such an infiltration was more evident at pressure side than at tension side. 2. Osteoclastic activity at pressure side began to be seen in 12 hours, increasing until 7 days. After then it decreased ; Such an activity was more evident in heavy force group than in light force group. 3. Tearing of periodontal ligament and vascular dilatation at tension side began to be seen in 12 hours, increasing until 3 days. After then it decreased ; Such an observation was more evident in heavy force group than in light force group, but there was no difference between groups in 14 days. 4. $\alpha$-1-antichymotrypsin expression in control group was positive, mainly in sulcular epithelium, but negative in periodontal membrane, pulp, bone cells. 5. $\alpha$-1-antichymotrypsin expression in experimental group was more positive in pressure side than in tension side ; The expression was a little more positive in cervical area of tooth until 3 days, but after 7days, it was more positive in apical area. 6. $\alpha$-1-antichymotrypsin expression in light force group began to be observed in 12 hours and reached to the greatest level in 7 days, after which it decreased ; In heavy force group, it was the greatest in 3 days, after which it decreased. 3 Expression in the periodontium was almost negative.

• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.775-782
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• 1998

The purpose of this study is to investigate the change of the EGFR mRNA expression in the rat gingival epithelium by the experimental tooth movement. We applied reciprocal force between the upper anterior teeth using NiTi open coil spring and stainless steel wire for 1, 2 3, 7 days. For the detection of EGFR mRNA, in situ hybridization was done in the tissue samples which were taken from the pressure and tension sides of teeth. The results were as follows ; 1. The expression of EGFR mRNA was increased application-time dependently. a. Day 1 mild expression on the basal and spinous cell layers b. Day 2 . moderate expression on the whole layers c. Day 3 : severe expression on the basal and spinous cell layers 4. Day 7 severe expression on the whole layers 2. The expression level of EGFR mRNA in the pressure and tension sides were similar during the whole Period of experiment except seven day application at which the cornified layer of the tension side showed moderate expression. 3. Removal of the appliance after 7-day force application lowered the level of EGRF mRNA expression. It was returned to the mild and control (rare) level at three and seven days after the removal, respectively. In conclusion, EFGR mRNA was increased by the experimental tooth movement on the rat ginigval epithelium. Up-regulation of EGFR mRNA in the gingival epithelium can be regarded as responses to the possible changes caused by the physical stersses to the oral environment to maintain the homeostatic conditions of the periodontium.