• Tuberculosis and Respiratory Diseases
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• v.44 no.2
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• pp.329-337
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• 1997

Background : Since endotracheal tube is the most important factor involved in the imposed work of breathing during mechanical ventilation, extubation of endotracheal tube is supposed to reduce respiratory work of patient. However, some patients show labored breathing after extubation despite acceptable blood gases. We investigated the changes of work of breathing before and after extubation and the factors involved in the change of WOB after extubation. Methods : The subjects were 34 patients(M : F = 20 : 14, mean age = $61{\pm}17yre$) who recovered from respiratory failure after ventilatory support and were considered to be ready for extubation. The patients with clinical or radiologic evidences of upper airway obstruction before endotracheal intubation for mechanical ventilation were excluded. Vital sign, physical examination, chest X-ray, work of breathing and other respiratory mechanic indices were measured prior to, immediately, 6, 24 and 48 hours after extubation serially. Definition of weaning failure after extubation was resumption of ventilatory support or reintubation of endotracheal tube within 48 hour after extubation because of respiratory failure. The patients were classified into group 1(decreased work of breathing), group 2(unchanged work of breathing) and group 3(increased work of breathing) depending on the statistical difference in the change of work of breathing before and after extubation. Results : Work of breathing decreased in 33%(11/34, group 1), unchanged in 41%(14/34, group 2) and increased in 26%(9/34, group 3) of patients after extubation compared with before extubation. Weaning failure occurred 9%(1/11) of group, 1, 28.6%(4/14) of group 2 and 44%(4/9) of group 3 after extubation(p = 0.07). The change of work of breathing after extubation was positively correlated with change of mean airway resistance(mRaw). (r = 0.794, p > 0.01). In three cases of group 3 whose respiratory indices could be measured until 48 hr after extubation, the change in work of breathing paralleled with the sequential change of mRaw. The work of breathing was peaked at 6 hr after extubation, which showed a tendency to decrease thereafter. Conclusions : Reversible increase of work of breathing after extubation may occur in the patients who underwent extubation, and the increase in mRaw could be responsible for the increase in work of breathing. In addition, the risk of weaning failure after extubation may increase in the patients who have increased WOB immediately after extubation.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.324-336
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• 2011

Objective: The aim of this study was to conduct three-dimensional finite element analysis of individual tooth displacement and stress distribution when a posterior retraction force of 200 g was applied at different positions of the retraction hook on the transpalatal arch (TPA) of a molar, and over different lengths of the lever arm on the maxillary anterior teeth in lingual orthodontics. Methods: A three-dimensional finite element model, including the entire upper dentition, periodontal ligaments, and alveolar bones, was constructed on the basis of a sample (Nissan Dental Product, Kyoto, Japan) survey of Asian adults. Individual movement of the incisal edge and root apex was estimated along the x-, y-, and z-coordinates to analyze tooth displacement and von Mises stress distribution. Results: When the length of the lever arm was 15 mm and 20 mm, the incisal edge and root apex of the anterior teeth was displaced lingually, with a maximum lingual displacement at the lever arm length of 20 mm. When the posterior retraction hook was on the root apex, the molars showed distal displacement. When the length of the lever arm was 20 mm, anterior extrusion was reduced and the crown of the canine displaced toward the buccal side, in which case, the retraction hook was on the edge, rather than at the center, of the TPA. Conclusions: The results of the analysis showed that when 6 anterior teeth were retracted posteriorly, lateral displacement of the canine and lingual displacement of the incisal edge and root apex of the anterior teeth occur without the extrusion of the anterior segment when the length of the lever arm is longer, and the posterior retraction hook is in the midpalatal area.

• Archives of design research
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• v.19 no.2 s.64
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• pp.241-250
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• 2006

Hangeul as the Korean unique characters were invented according to some character-making principles and based on scholars' exhaustive researches. While most of the characters in the world evolved naturally, Hangeul was invented based on a precise linguistic analysis of the time, and therefore, it is most scientific and reasonable among various characters throughout the world. Nevertheless, Hangeul typeface designs do not seem to inherit the ideology of scientific and reasonable Hangeul correctly. For the square forms have been used intact due to the influences from the Chinese characters which prevailed during the time. If a single set of square characters should be designed, as much as 11,172 fonts should be designed, which suggests that advantages of Mangeul may not well be used fully; Hangeul was invented to visualize every sound with the combinations of 28 vowels and consonants. Problems of such square fonts began to be identified since 1900's when typewriters were introduced first from the West. Since a typewriter is designed with 28 characters laid out on its keyboard by using such combinations, the letters may be easily combined on it. The so-called the flexibility square-format typeface was born as such. Specially, the three-pairs fonts of these can be combined up to 67 letters including vowels and consonants. The three-pairs fonts system can help to solve the problems arising form the conventional square fonts and inherit the original ideology of Hangeul invention. This study aims to review the history of the three-pairs fonts designs facilitated by mechanic encoding of Hangeul and thereupon, suggest some desirable directions for future Hangeul fonts. Since the flexibility square-format typeface is expected to evolve more and more owing to development of the digital technology, they would serve our age of information in terms of both functions and convenience. Just as Hunminjongum tried to be literally independent from the Chinese characters, so the flexibility square-format typeface designs would serve to recover identity of our Hangeul font designs.