• The korean journal of orthodontics
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• v.27 no.6 s.65
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• pp.929-941
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• 1997

Optimal force for orthodontic treatment is the force that produces a rapid rate of tooth movement without discomfort to the Patient or ensuing tissue damage. Recently considerable interest has been generated in the application of magnets as a way to obtain an optimal force. The purpose of the present study was to investigate the effect of static magnetic fields of Sm-Co magnets on molecular and cellular activities. The distance of erythrocyte sedimentation was measured directly, and the activities and the syntheses of $Fe^{2+}$-related enzymes (catalase and NO synthase) and non $Fe^{2+}$-related enzyme (lactic dehydrogenase) were assayed by the spectrophotometer. The growth and the proliferation of osteoblast-like cells $MC_3T_3-E_1$ were determined by the crystal violet staining and the ${^3}H$-thymidine incorporation. The erythrocytes were exposed to the pole face flux density of 1,400 G (gauss), and the enzymes and osteoblast-like cells $MC_{3}T_3-E_1$ were exposed to the flux density of 7,000 G. The results obtained were as follows: 1. The distance of sedimentation of erythrocyte was not affected by the static magnetic fields. 2. The activities of catalase and lactic dehydrogenase were not affected by the static magnetic fields. 3. The intracellular syntheses of NO synthase and lactic dehydrogenase were not affected by the static magnetic fields. 4. The growth and the proliferation of cultured osteoblast-like cells $MC_{3}T_3-E_1$ were not affected by the static magnetic fields. These results suggested that the molecular and cellular activities were not significantly influenced by the static magnetic fields.

• Journal of the Korean Wood Science and Technology
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• v.28 no.4
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• pp.41-50
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• 2000

Cement-bonded particleboard is being used as outdoor siding material all over the world, because this composite particularly bears a light weight, high resistance against fire, decay, and crack by cyclic freezing and thawing, anti-shock property, and strength enhancement. Construction systems are currently changing into a frame-building style and wooden houses are being constructed with prefabrication type. Therefore, they require a more durability at outdoor-exposed sides. In this study, the cement hydration property for Korean pine particle, Japanese larch particle and face- and middle layer particles (designated as PB particle below) used in Korean particleboard-manufacturing company was investigated, and the rapid manufacturing characteristics of cement-bonded particleboard by supercritical $CO_2$ curing was evaluated. Korean pine flour showed a good hydration property, however, larch flour showed a bad one. PB particle had a better hydration property than larch flour. The addition of $Na_2SiO_3$ indicated a negative effect on hydration, however, $MgCl_2$ had a positive one. Curing by supercritical $CO_2$ fluid gave a conspicuous enhancement in the performances of cement-bonded particleboards compared to conventional curing. $MgCl_2$ 3%-added PB particle had the highest properties, and $MgCl_2$ 1%-added Korean pine particle had the second class with the conditions of cement/wood ratio of 2.7, a small fraction-screened particle and supercritical curing. On the contrary, the composition of non-hammermilled or large fraction-screened particle at cement/wood ratio of 2.2 was poorer. Also, the feasibility for actual use of 3%-added, small PB particle-screened fraction was greatest of all the conventional curing treatments. Relative superiority of supercritical curing vs. conventional curing at dimensional stability was not so apparent as in strength properties. Through the thermogravimetric analysis, it was ascertained that the peak of a component $CaCO_3$ was highest, and the two weak peaks of calcium silicate hydrate and ettringite and $Ca(OH)_2$ were present in supercritical treatment. Accordingly, it was inferred that the increased formation of carbonates in board contributes to strength enhancement.

• Journal of Chest Surgery
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• v.32 no.2
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• pp.171-174
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• 1999

Background: Hyperhidrosis of the palms, axillae and face has a strong negative impact on social and professional life. The present existing non-operative therapeutic options seldom give sufficient relief and have a transient effect. A definitive cure can be obtained by upper thoracic sympathectomy. However, this is offset by the occurrence of a high rate of side effects, such as embarrassing compensatory sweating. Material and Method: From Sep. 1997 to Feb. 1998, 89 cases of the needle(2 mm) thoracoscopic thoracic sympathicotomy were performed. The second thoracic ganglion was resected by cutting with a endoscissors. Result: A bilateral procedure takes less than 25 min and requires just one night in hospital. There have been no mortality or life-threatening complications. One patient(<2%) required intercostal drainage because of pneumothorax. Primary failure occurred in one cases(<2%) and recurrent hyperhidrosis occurred in no cases. The patients with failure was successfully re-sympathicotomy. At the end of postoperative follow-up(median 3 months), 96.6% of the patients were satisfied. Compensatory sweating occurred in 57 cases(64.0%) with fourteen of those cases classified as either embarrassing in 10 cases(11.2%) or disabling in 4 cases(4.5%). Conclusion: Endoscopic transthoracic sympathicotomy is an efficient, safe and minimally invasive surgical method for the treatment of palmar and craniofacial hyperhidrosis.