임플랜트전산화단층촬영시 central panoramic curve의 변화가 하악골의 영상 재구성에 미치는 영향

학위논문(석사)--서울대학교 대학원 :치의학과 구강악안면방사선학전공,1998.Maste

Benign lymphoepithelial lesion arising in the parotid gland

The authors diagnosed a 33 years old female as benign lymphoepithelial lesion after undergoing clinical, radiological and histopathological examinations and the characteristics were as follows : 1. Clinically, the patient complained of painless bilateral swelling of the parotid glands and dryness of the palate. Rheumatoid factor was detected in her serum. 2. Sialograms showed punctate or globular collections of contrast media distributed evenly throughout the parotid glands in so-called 'cherry blossom' or 'leafless fruit-laden tree' appearance. 3. A salivary gland scan showed no uptake of radioisotopes by the parotid glands. 4. At Tl-weighted imaging of PNS MRI, the lesions had the same signal intensity as the rest of the gland. At TI-weighted imaging, the lesions could be seen as high signal intensity 1.3 cm and 2.1 cm in diameter in the left and the right parotid gland respectively. 5. Ultrasonogram showed sonolucent lesions 20×15mm and 17×14mm in size in the lower part of the left parotid gland and another 18×11mm in size in the lower part of the parotid gland as well as many other small sonolucent lesions. 6. Histopathologically, lymphocytic infiltration replacing the normal acini and lymphoid follicles containing germinal centers could be seen. Epimyoepithelial islands were scattered throughout the lesion and benign lymphoepithelial cysts were also observed

Invariant pattern recognition with morphological filters and third-order neural networks

학위논문(석사) - 한국과학기술원 : 전기 및 전자공학과, 1993.2, [ [ii], 51 p. ]한국과학기술원 : 전기 및 전자공학과

조합 최적화 문제를 위한 휴리스틱 연산자를 이용한 하이브리드 진화 알고리즘

학위논문(박사) - 한국과학기술원 : 전기및전자공학과, 1997.8, [ xi, 129 p. ]Recently, there have been much research of robust and powerful optimization methods for solving large and difficult combinatorial problems. As a result, several effective stochastic search algorithms have shown up in the literature, for example, simulated annealing, tabu search, and evolutionary algorithms. Evolutionary algorithms inspired by the natural process of evolution are attracting attentions for dealing with global optimization. The main feature of evolutionary algorithms is the maintenance of a set of solutions that are searched in parallel and the adoption of perturbation mechanism analogous to biological operators. Accordingly, they can be easy parallelizable compared to other methods. There have been a lot of empirical evidences indicating that evolutionary algorithms are good optimization methods, resulting in rapid enlargement of application areas. However, most of the applications have been performed without considering how effective evolutionary algorithms are in solving the problems compared to other search algorithms. This thesis consists of two parts. In the first part, we investigate the features of evolutionary algorithms and examine the efficacy of them by carefully controlled empirical comparisons with simulated annealing. As problem size and ruggedness of the landscape increase, the contribution of crossover to evolutionary search becomes less useful and the evolutionary search becomes less efficient than simulated annealing. The second part of this thesis deals with two possible hybridization techniques to enhance performance of canonical evolutionary algorithms. The first hybrid incorporates independent sophisticated heuristic local search to evolutionary algorithms so as to overcome problems of evolutionary algorithms identified in the first part of this thesis. Experimental results demonstrate that the hybrid is capable of clearly outperforming canonical evolutionary algorithms and is better than simulated annealing for some cla...한국과학기술원 : 전기및전자공학과

INFLUENCE OF CENTRAL PANORAMIC CURVE DEVIATION ON THE MANDIBULAR IMAGE RECONSTRUCTION IN THE IMPLANT CT

The purpose of this study was to investigate an influence of the change of central panoramic curves on the image reconstruction in the dental implant CT. The author designed three experimental groups according to the location of central panoramic curve. In group A, central panoramic curve was determined as the curve connecting the center of roots from the first premolar to the first molar. In group B, central panoramic curve was determined as the line connecting the lingual cortical plate at the level of the mesial aspect of the first premolar with the buccal cortical plate at the level of the mesial aspect of the first molar. In Group C, central panoramic curve was determined as the line connecting the buccal cortical plate at the level of the mesial aspect of the first premolar with the lingual cortical plate at the level of the mesial aspect of the first molar. Twenty four reformatted CT images was acquired from four mandibles embedded in the resin block and twenty four contact radiographs of dog specimens were acquired. Each Image was processed under Adobe Photoshop program analysed by MSPA(mandible/maxilla shape pattern analysis) variables such as MXVD, MXHD, UHD, MHD, and LHD. The obtained results were as follows ; 1. The mean of MXVD variable was 19.9, 20.2, and 20.0 in group A, B, and C, respectively, which were smaller than actual value 20.5. But, there was no significant difference among 3 groups (p>0.05). 2. The mean of MXHD, UHD, MHD, and LHD variables in group A, B, and C was 11.9, 12.2, and 12.3; 9.3, 9.5, and 9.6; 10.0, 10.3, and 10.3; 9.2, 9.3, and 9.4 respectively which were equal to or greater than the actual value 11.8, 9.3, 10.0, and 9.2. But, there was no significant difference among 3 groups (p>0.05). 3. The number of noneffective observations with difference over or under 1 mm with comparison to the actual value was 24(20%), 58(48.3%), and 52(43.3%), respectively, in group A, B, and C. 4. In group A, the number of observations over 1 mm and under 1 mm was 9 and 15, respectively, but in group Band C, the number of observations over 1 mm was more than under 1 mm

Accuracy of CT image in measuring the mandible for implant : Effect of mandibular position and gantry angle

We used five adult dog mandibles embedded in resin block and six different cross-sectional planes for each mandible were choosen. According to the angle of mandibular occulsal plane to vertical plane(mandibular angle) and gantry angle of CT machine, we classified 4 experimental groups and 1 control group. The control group images were taken at the mandibular angel 0º and gantry angle 0º . The experimental images were taken at the mandibular angle 15º and gantry angle 0º(group 1); 30º and 0º(group 2); 15º and 15º(group 3); 30º and 30º(group 4), respectively. Using the reformatted cross-sectional images, the distance from the mandibular canal to the alveolar crest and the distance from the mandibular canal to the buccal cortex and to the lingual cortex was measured and compared. The obtained results were as follows : 1. The distance from the mandibular canal to the alveolar crest of group 1 and 2 was larger than control group, but the distance of group 3 and 4 was smaller. The distance from the mandibular canal to the buccal cortex and to the lingual cortex of all experimental groups was smaller than control group. 2. The distance from the mandibular canal to the alveolar crest showed the largest difference from control group in all experimental groups, especially in group 2 and 4(p<0.05). 3. In the distance from the mandibular canal to the alveolar crest, the number of deviation value under 1 ㎜ was 20 in group 3 and was 11 in group 2 and 4, respectively. 4. The deviation value of the distance from the mandibular canal to the buccal cortex and to the lingual cortex was under 1 ㎜ in most cases.이 논문은 1997년도 서울대학교병원 일반연구비(04-95-44) 지원에 의해 이루어진 것임

NONSPECIFIC INFLAMMATION IN THE FACE

Patient with complaints of swelling, pain in the maxillaly region and discomfort visited Seoul National University Dental Hospital in August last year. Clinical examination and diagnostic imagings implied he was suffered from fungal hyphal infection but no causative fungus was found by the histopathologic and microbiologic investigation. Therefore he was diagnosed with nonspecific inflammation. But as yet, we do think this case is very similar to some kinds of mucormycosis. So we presented this case for more thorough discussion.Followings are founded in the examination. 1. Patient had suffered from Diabetes mellitus and complained of stuffness, headache, swelling in buccal cheeks and paresthesia And we found more maxillary bony destruction and ulcer with elevated margin in the palate by clinical examination. 2. In the first visit, Plain films revealed general bony destruction of the maxilla, radiopaqueness in the sinonasal cavities. or and MRI showed soft tissue mass filled in the paranasal sinus except frontal sinus and bony destruction in involved bones. 3. No causative bacteria and fungus was found in the biopsy and microbiologic cultures. 4. Caldwell-Luc operation and curettage were carried and antJbiotics were taken for 4 months. But now he was worse than in the past 5. In the second visit, involvement of orbit, parapharyngeal sinus, clivus, cavernous sinus and middle cranial fossa were seen clearly in the or and MRI