• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.422-425
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• 2008

Recently, electronic products and related parts are required to have thin thickness because of small form factor. To go with the trend, LGP(light guide plate) of LCD BLU(Liquid Crystal Display Back light unit: It is one of kernel parts of LCD) for cell phone has the thickness of 0.3 mm and the battery case of cell phone has 0.25 mm. Accordingly, high speed injection molding is required to make products which have thin thickness. High speed injection molding means that the resin is injected into the cavity at higher than normal speed avoiding short shot. In the case of hydro-mechanical high speed injection machine, it requires the design for hydraulic unit to make high injection speed and the design for control unit to control hydraulic unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3 mm thickness.

• Restorative Dentistry and Endodontics
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• v.39 no.2
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• pp.120-125
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• 2014

Use of an apical plug in management of cases with open apices has gained popularity in recent years. Biodentine, a new calcium silicate-based material has recently been introduced as a dentine substitute, whenever original dentine is damaged. This case report describes single visit apexification in a maxillary central incisor with necrotic pulp and open apex using Biodentine as an apical barrier, and a synthetic collagen material as an internal matrix. Following canal cleaning and shaping, calcium hydroxide was placed as an intracanal medicament for 1 mon. This was followed by placement of small piece of absorbable collagen membrane beyond the root apex to serve as matrix. An apical plug of Biodentine of 5 mm thickness was placed against the matrix using pre-fitted hand pluggers. The remainder of canal was back-filled with thermoplasticized gutta-percha and access cavity was restored with composite resin followed by all-ceramic crown. One year follow-up revealed restored aesthetics and function, absence of clinical signs and symptoms, resolution of periapical rarefaction, and a thin layer of calcific tissue formed apical to the Biodentine barrier. The positive clinical outcome in this case is encouraging for the use of Biodentine as an apical plug in single visit apexification procedures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.455-463
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• 2000

In order to develop nondestructive techniques for the quantitative estimation of creep damage a series of crept copper samples were prepared and their ultrasonic velocities were measured. Velocities measured in three directions with respect to the loading axis decreased nonlinearly and their anisotropy increased as a function of creep-induced porosity. A progressive damage model was described to explain the void-velocity relationship, including the anisotropy. The comparison of modeling study showed that the creep voids evolved from sphere toward flat oblate spheroid with its minor axis aligned along the stress direction. This model allowed us to determine the average aspect ratio of voids for a given porosity content. A novel technique, the back propagation neural network (BPNN), was applied for estimating the porosity content due to the creep damage. The measured velocities were used to train the BP classifier, and its accuracy was tested on another set of creep samples containing 0 to 0.7 % void content. When the void aspect ratio was used as input parameter together with the velocity data, the NN algorithm provided much better estimation of void content.

• Journal of Chest Surgery
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• v.9 no.2
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• pp.287-292
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• 1976

This is a report of a case of congenital esophageal hiatus hernia, occurring in a younger child at the age of one year and two months. The child was suffered from vomiting (intermittently coffee-ground vomitus or blood-flecked vomitus), coughing, and high fever for about 3 months.Diagnosis was confirmed by the radiologic barium study of the gastrointestinal tracts. The herniated organs were entire stomach and a part of the transverse colon. They were located in the right chest. The etiologic pathology was mainly congenital developmental defect of the musculature of the diaphragm, forming the posterior margin of the esophgeal hiatus, and additionally slight shorted esophagus. After reduction of herniated organs back to the abdominal cavity through abdominal approach, herniorrhaphy was performed through transthoracic approach with modified Allison's procedure. At the same time, any associated anomalies, such as hypertrophic pyloric stenosis, were not seen. Postoperative course was uneventful.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.250-254
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• 2000

We have constructed laser Doppler velocimetry system using self-mixing effect with a semiconductor laser. This technology is based on the frequency mixing phenomena which occurs when light scattered back from the moving object into the laser cavity interferes with light inside the laser. We have compared the value of Doppler shifted frequency with the velocity variation of the wheel. Frequency dependence on the angle between the moving direction of rotating aluminum wheel and the incident beam also have been proved. As an illustration of the performance of the velocimeter, velocity measurements of a rotating disk are described. Doppler signal shows a good linear relationship with velocity of rotating disk.

• Journal of Chest Surgery
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• v.6 no.1
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• pp.109-112
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• 1973

Bochdalek hernia is the most common congenital diaphragmatic hernia and that of the foramen of Bochdalek is rare in right side of the diaphragm. Two cases of right Bochdalek hernia were reported in literatures published in Korea. The first case was associated with hypoplasia of the lung and could not be survived. The second case [four months old male infant] was operated on August 28, 1971. at Ewha University Hospital arid survived. The third case was a three months old male infant who had been born at 8th lunar month in a private clinic. During the period of three months prior to admission this premature infant was suf-fered from mild respiratory distress measured as pneumonia. On December 20. 1972, this infant was admitted at Kyung Hee University Hospital with severe respiratory distress developed abruptly. Chest X-ray examination [barium study] demonstrated right diaphragmatic hernia. Right hemithorax was filled with intestines and right lobe of the liver which were repositioned back into the peritoneal cavity through the foramen of Bochdalek. 3. 0 cm x3.5 cm in size, and the defect was closed with interrupt mattress sutures. There was hypospadia with chordee but no other associated anomalies such as hypoplasia of the lung, malrotation or malfixation of intestines, and cardiovascular anomalies. The Postoperative hospital course was not eventful and the baby was discharged on the 14th postoperative day.

• Archives of Craniofacial Surgery
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• v.20 no.6
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• pp.347-353
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• 2019

Most orbital surgeons believe that it's difficult to restore the primary orbital wall to its previous position and that the orbital wall is so thin that cannot be firmly its primary position. Therefore, orbital wall fractures generally have been reconstructed by replacing the bony defect with a synthetic implant. Although synthetic implants have sufficient strength to maintain their shape and position in the orbital cavity, replacement surgery has some drawbacks due to the residual permanent implants. In previous studies, the author has reported an orbital wall restoring technique in which the primary orbital wall fragment was restored to its prior position through a combination of the transorbital and transantral approaches. Simple straight and curved elevators were introduced transnasally to restore the orbital wall and to maintain temporary extraorbital support in the maxillary and ethmoid sinus. A transconjunctival approach provided sufficient space for implant insertion, while the transnasal approach enabled restoration of the herniated soft tissue back into the orbit. Fracture defect was reduced by restoring the primary orbital wall fragment to its primary position, making it possible to use relatively small size implant, furthermore, extraorbital support from both sinuses decreased the incidence of implant displacement. The author could recreate a natural shape of the orbit with the patient's own orbital bone fragments with this dual approach and effectively restored the orbital volume and shape. This procedure has the advantages for retrieving the orbital contents and restoring the primary orbital wall to its prior position.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.36 no.1
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• pp.13-15
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• 2014

Epithelial cysts are benign epithelium-lined lesions that contain fluid or semisolid material. Most epithelial cysts in the oral cavity occur in the anterior part of the mouth floor. Cysts arising on the uvula in a cleft palate patient are rare. Intraoral examination in a 14-month-old boy with a complete cleft lip and palate revealed a cystic lesion on the right uvula. The lesion was excised and push-back palatorrhaphy with Z-plasty on the uvula was performed. Histopathological examination diagnosed an epithelial cyst. We report a case of an epithelial cyst of uvula in a patient with a unilateral complete cleft lip and palate.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.377-386
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• 1993

The purpose of this study was to evaluate the disinfection efficacy of root canal irrigation method and irrigation solution in infected root canals. Access cavity were prepared in single-rooted extracted human teeth and each canals were prepared with step-back method and sterilized with ethylene oxide gas. Prepared teeth were experimentally inoculated in the canals for 30 minutes with four aerobes(Streptococcus mutans, Stapylococcus aures, Streptococcus sanguis, and E. coli) and two anaerobes(Streptoccus intermedius, and Clostrium perfringens). Normal saline, 3% $H_2O_2$, and 3% NaOCl were used as irrgation solutions. And root canals were irrigated with each irrigation solutions manually with disposible syringe or ultrasonic instument. (Apoza Uitrasonc, Taiwan). The irrigation effect on the eradication of S. aures and S. intermedius with normal saline was not similar between manual method and ultrasonic method. No significant differences were observed in the eradication of E. coli and C. perfringens among the irrigation solution and irrespective of the irrigation methods. In S. aurues and S. mutans, there was somewhat different eradication effect according to irrigation solutions, but there was no significant difference between manual method and ultrasonic methods. These results suggest that ultrasonic irrigation method with saline is more effective in some strains than manual irrigation.

• Transactions of Materials Processing
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• v.22 no.4
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• pp.183-188
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• 2013

Scroll compressors are widely used in air conditioning systems and in automobiles due to their low pressure loss, minimal vibrations, and light-weight. Open-die forging with back pressure is used to forge the rotating scroll, and it requires special care since the forging die can be severely damaged at the fixed end of the spiral cavity similar to a fracture of a cantilever beam. To overcome the inevitable weakness of the forging die due to such damage, an innovative design is necessary. In this study, structural analysis using the finite element method was conducted to determine the reason for the fracture of the forging die. A novel design to avoid stress concentrations and vertical deflection, causing serious damage to the die, is suggested.