• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.43-54
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• 1999

The effects of equivalence ratio and pressure on burnt gas temperature in premixed fuel rich propane-oxygen-inert gas combustion are investigated over the wide ranges of equivalence ration from 1.5 to 2.7 and pressure from 0.1 to 7 MPa by using a specially designed disk -type constant-voume combustion chamber, The premixtures are simultaneously ignited by eight spark plugs located on the circumference of combustion chamber with 45 degree interals. The eight converging flames compress the end gases to high pressures. The burnt gas temperature is meausured by the nmodifie dtow-colr pyrometry method. The transmissivity in the chamber center during the final stage of combustion at the hightest pressure is meausred by in situ laser extinction method. It is found that a temperature difference between the burnt gas temperature measured by mofidied and conventrational two-color method is 10 to 20 K, but the accuracy of the modified two-color methdo is higher if the local transmissivity in observed region is uniform , and the combustion at higher pressures results gas density conditions and the burnt gas temperature increases as the volume fraction of argon is increased because the specific heat of argon is lower compared to that of nitrogen with a constant equivalence ratio.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.1
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• pp.55-62
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• 2007

Radical paring of the cleft edge during primary cleft lip operation or repeated secondary surgeries can result in tightness of the upper lip. In case, the degree of the resulting side-to-side tension is very severe, the possibility of a lip switch flap must be considered. When the lip tightness accompanies a loss of more than two-thirds of the Cupid's bow, an Abbe flap is an alternative. The disadvantages of Abbe flap are scar formation on the lower lip, design of incision line on the upper lip, disharmony of colors, and the dysfunction of the orbicularis muscle. These problems have been recognized in the literature and extreme discretion has been advised in its application. We experienced four cases of Abbe flap operation which were designed differently to correct the secondary unilateral or bilateral cleft-lip nasal deformities. The Abbe flap operations resulted in removal of the scars and tightness of the upper lip, reconstruction of the Cupid's bow, lengthening of the columella, and therefore secondary cleft-lip nasal deformity could be corrected. It is thought that carefully applied Abbe flap is an appropriate method to relieve horizontal tightness or flattening of the upper lip which occured after primary operation of cleft lip.

• Education of Primary School Mathematics
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• v.24 no.4
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• pp.247-264
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• 2021

The area of a trapezoid is an important concept to develop mathematical thinking and competency, but many students tend to understand the formula for the area of a trapezoid instrumentally. A clue to solving these problems could be found in Dienes' theory of learning mathematics and Watson and Mason' concept of example spaces. The purpose of this study is to obtain implications for the teaching and learning of the area of the trapezoid. This study analyzed the example spaces constructed by students in learning the area of a trapezoid based on Dienes' theory of learning mathematics. As a result of the analysis, the example spaces for each stage of math learning constructed by the students were a trapezoidal variation example spaces in the play stage, a common representation example spaces in the comparison-representation stage, and a trapezoidal area formula example spaces in the symbolization-formalization stage. The type, generation, extent, and relevance of examples constituting example spaces were analyzed, and the structure of the example spaces was presented as a map. This study also analyzed general examples, special examples, conventional examples of example spaces, and discussed how to utilize examples and example spaces in teaching and learning the area of a trapezoid. Through this study, it was found that it is appropriate to apply Dienes' theory of learning mathematics to learning the are of a trapezoid, and this study can be a model for learning the area of the trapezoid.

• Journal of Chest Surgery
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• v.37 no.3
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• pp.235-244
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• 2004

Anatomic correction of the transposition of the great arteries (TGA) or Taussig-Bing anomaly by means of the arterial switch operation is now accepted as the therapeutic method of choice. This retrospective study was conducted to evaluate the risk factors for operative deaths and the efficacy of technical modification of the coronary transfer. 85 arterial switch operations for TGA or Taussig-Bing anomaly which were performed by one surgeon from 1994 to July 2002 at Dong-A university hospital were included in this retrospective study Multivariate analysis of perioperative variables for operative mortality including technical modification of the coronary transfer was peformed. Overall postoperative hospital mortality was 20.0% (17/85). The mortality before 1998 was 31.0% (13/42), but reduced to 9.3% (4/43) from 1998. The mortality in the patients with arch anomaly was 61.5% (8/13), but 12.5% (9/72) in those without arch anomaly. In patients who underwent an open coronary reimplantation technique, the operative mortality was 28.1% (18/64), but 4.8% (1/21) in patients undergoing a technique of reimplantation coronary buttons after neoarotic reconstruction. Risk factors for operative death from multivariated analysis were cardiopulmonary bypass time ($\geq$ 250 minutes), aortic cross-clamping time ($\geq$ 150 minutes), aortic arch anomaly, preoperative event, and open coronary reimplantation technique. Operative mortality has been reduced with time. Aortic arch anomaly and preoperative events were important risk factors for postoperative mortality. However atypical coronary artery patterns did not work as risk factors. We think that the technical modification of coronary artery transfer played an important role in reducing the postoperative mortality of arterial switch operation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.100-105
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• 2003

25Cr-20Ni series strainless steel have an excellent high temperature strength, high oxidation and high corrosion resistance. However, further improvement can be creep strength by work hardening prior creep. In the present study, the effect of prestraining at room temperature on the creep behavior of a Class M(STS310S) and a Class A(STS310J1TB) alloy containing precipitates have been examined. Prestraining was carried out at room temperature and range of prestrain was $0.5{\sim}2.5$ % at STS310J1TB and $2.0{\sim}7.0$ % at STS310S. Creep behavior and creep rate of pre-strained specimens were compared with that of virgin specimens. Room temperature prestraining produced the creep life that is longer than that of a virgin specimen both for STS310J1TB and STS310S when creep test carried out at the temperature lower than recrystallization temperature. The reason for this improvement of creep life was ascribable to the interaction between dislocations and precipitates in addition to the dislocation-dislocation interaction in STS310J1TB and the dislocation-dislocation interaction in STS310S. The beneficial effect of prestraining in STS310J1TB was larger than that of STS310S.

• Clinics in Shoulder and Elbow
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• v.10 no.2
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• pp.212-219
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• 2007

Purpose: To determine the causes of the surgical treatment results in glenoid fracture by a retrospective analysis. Materials and methods: From March 1999 to February 2004, 9 patients who underwent an open reduction due to a glenoid fracture were reviewed. The modified Ideberg classification was used. There were 1, 3, 2, 1 and 2 cases of modified Ideberg type I, II, III, V, and VI, respectively. The internal fixators were a reconstruction plate, a small plate, a one-third tubular plate, a small screw, and a cannulated screw in 6, 1, 3, 3 and 1 case, respectively. The constant score and Adam's functional assessment method were used to evaluate the postoperative shoulder function. Results: The average time for fracture union was 7 weeks. The functional assessment was excellent in 4 cases, good in 3 cases, and fair in 2 cases. There were two complications related to surgery; articular screw encroachment, and inferior glenoid bone resorption without instability. Conclusion: A glenoid fracture with glenohumeral instability or displaced that was treated by open surgery showed good clinical results. Moreover, the more comminuted fracture had a lower functional score.

• Clinics in Shoulder and Elbow
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• v.10 no.1
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• pp.146-149
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• 2007

Congenital undescended scapula is congenital structural abnormality which affects only one side usually. Scapula located higher than the usual and rotating deformity that inferior angle to medial side, superior angle to lateral side is common. This report presents one case of the surgical therapy of a sprengel deformity patient who passed an optimal operation period with age $3{\sim}7$years old, and includes brief review of the literature. 7 years old boy whose chief complaint was the limitation of left scapular-thoracic movement and he had an omovertebral bone bridge and periscapular muscle atrophy. There was improvement of motion ranges and cosmetic problems after surgical treatment.

• Tunnel and Underground Space
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• v.9 no.2
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• pp.149-157
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• 1999

A powerful numerical method that can be used for that purpose is the Discontinuous Deformation Analysis (DDA) method developed by Shi in 1988. In this method, rock masses are treated as systems of finite and deformable blocks. Large rock mass deformations and block movements are allowed. Although various extensions of the DDA method have been proposed in the literature, the method is not capable of modeling water-block interaction that is needed when modeling surface or underground excavation in fractured rock. This paper presents a new extension to the DDA method. The extension consists of hydro-mechanical coupling between rock blocks and water flow in fractures. A example of application of the DDA method with the new extension is presented. The results of the present study indicate that fracture flow could have a destabilizing effect on the tunnel stability.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.156-160
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• 2013

A duplex polymerase chain reaction (PCR) method was developed to detect unapproved genetically modified (GM) potato (EH92-527-1) in Korea. The UDP-glucose pyrophosphorylase (UGP) gene was selected as an endogenous reference gene for potato and used to validate the specificity for 14 different crops. The primer pair EH92-F/R was designed to amplify the junction sequence between the genome and transgenic region introduced in GM potato. Its specificity was also validated using several different GM events. The detection limit of the duplex PCR method is approximately 0.05%. This duplex PCR method could be useful for monitoring cultivation of unauthorized GM potato in Korea.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.233-245
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• 2021

Many studies on the microstructures in rocks have been conducted using experimental methods with various equipment as well as natural rock studies to see the development of microstructures and understand their mechanisms. Grain boundary migration of mineral aggregates in rocks could cause grain growth or grain size changes during metamorphism or deformation as one of the main recrystallization mechanisms. This study suggests improved ways regarding the analog material experiments with reformed equipment to see sequential observations of these grain boundary migration. It can be more efficient than the existing techniques and carry out an appropriate microstructure analysis. This reformed equipment was implemented to enable optical manipulation by mounting polarizing plates capable of rotating operation on a stereoscopic microscope and a deformation rig capable of experimenting with analog materials. The equipment can automatically control the temperature and strain rate of the deformation rig by microcontrollers and programming and can take digital photomicrographs with constant time intervals during the experiment to observe any microstructure changes. The composite images synthesized using images by rotated polarizing plates enable us to see more accurate grain boundaries. As a rock analog material, norcamphor(C7H10O) was used, which has similar birefringence to quartz. Static grain growth and simple shear deformation experiments were performed using the norcamphor to verify the effectiveness of the equipment. The static grain growth experiments showed the characteristics of typical grain growth behavior. The number of grains decreases and the average grain size increases over time. These case experiments also showed a clear difference between the growth curves with three temperature conditions. The result of the simple shear deformation experiment under the medium temperature-low strain rate showed no significant change in the average grain size but presented the increased elongation of grain shapes in the direction of about 53° regarding the direction perpendicular to the shearing direction as the shear strain increases over time. These microstructures are interpreted as both the plastic deformation and the internal recovery process in grains are balanced by the deformation under the given experimental conditions. These experiments using the reformed equipment represent the ability to sequentially observe changing the microstructure during experiments as desired in the tests with the analog material during the entire process.