• 대한수학회보
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• 제46권5호
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• pp.823-833
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• 2009

It is well-known that if a convex hyperbolic polygon is constructed as a fundamental domain for a subgroup of the modular group, then its translates by the group elements form a locally finite tessellation and its side-pairing transformations form a system of generators for the group. Such hyperbolically convex polygons can be obtained by using Dirichlet's and Ford's polygon constructions. Another method of obtaining a fundamental domain for subgroups of the modular group is through the use of a right coset decomposition and we call such domains standard fundamental domains. In this paper we give subgroups of the modular group which do not have hyperbolically convex standard fundamental domain containing only inequivalent cusps.

• 대한수학회보
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• 제51권1호
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• pp.287-301
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• 2014

In this paper, we prove a necessary optimality theorem for a nonsmooth optimization problem in the face of data uncertainty, which is called a robust optimization problem. Recently, the robust optimization problems have been intensively studied by many authors. Moreover, we give examples showing that the convexity of the uncertain sets and the concavity of the constraint functions are essential in the optimality theorem. We present an example illustrating that our main assumptions in the optimality theorem can be weakened.

• Journal of Korean Neurosurgical Society
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• 제58권2호
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• pp.144-146
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• 2015

Postdural punctural headache (PDPH) following spinal anesthesia is due to intracranial hypotension caused by cerebrospinal fluid (CSF) leakage, and it is occasionally accompanied by an intracranial hematoma. To the best of our knowledge, an intracranial chronic subdural hematoma (CSDH) presenting with an intractable headache after a cervical epidural steroid injection (ESI) has not been reported. A 39-year-old woman without any history of trauma underwent a cervical ESI for a herniated nucleus pulposus at the C5-6 level. One month later, she presented with a severe headache that was not relieved by analgesic medication, which changed in character from being positional to non-positional during the preceding month. Brain magnetic resonance imaging revealed a CSDH along the left convexity. Emergency burr-hole drainage was performed and the headache abated. This report indicates that an intracranial CSDH should be considered a possible complication after ESI. In addition, the event of an intractable and changing PDPH after ESI suggests further evaluation for diagnosis of an intracranial hematoma.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.466-469
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• 1996

In this paper, we present the global minimization condition by an informal analysis of the Langevine competitive learning neural network. From the viewpoint of the stochastic process, it is important that competitive learning guarantees an optimal solution for pattern recognition. By analysis of the Fokker-Plank equation for the proposed neural network, we show that if an energy function has a special pseudo-convexity, Langevine competitive learning can find the global minima. Experimental results for pattern recognition of handwritten numeral data indicate the superiority of the proposed algorithm.

• 대한치과의사협회지
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• 제23권6호통권193호
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• pp.527-538
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• 1985

The purpose of this study is to evaluate the chronologic changes of the soft tissue profile in 6 to 11 years children. The author analyzed 174 cephalometric roentgenograms of 13 boys and 16 girls taken from the ages of 6 to 11 to assess the growth changes of the soft tissue profile. The results were obtained as follow: 1. Means, standard deviation and coefficient of variation of children were obtained. 2. Items which showed difference between males and females in longitudinal study were prn. Sn. A', and Ls that were greater than females variation. 3. With age, thickness of the soft tissue were increased except Ls. 4. Nasolabial angle and facial convexity had no significant change with age and sex.

• 대한치과교정학회지
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• 제23권4호
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• pp.475-483
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• 1993

The purpose of this study was to investigate the treatment effects on anterior crossbite patients using chin cap and labiolingual arch appliance. In the present study, I statistically evaluated measurement values on a cephalogram before and after treatment form twenty anterior crossbite cases. The results were as follows: 1. In the craniofacial patterns, cranial base increased after treatment. 2. In the maxillo-mandibular relationship, ANB and Facial convexity significantly increased. 3. In the denture patterns, occlusal plane, Ul to FH and Overjet significantly increased. On the contrary overbite decreased significantly. Lower incisors inclined lingually. 4. In the soft tissue profile changes, lower lip protrusion was signifacantly improved.

• 대한치과교정학회지
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• 제9권1호
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• pp.15-22
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• 1979

This study was undertaken to establish the cephalometric standard of Hellman dental age IVA group of Korean. The subjects consisted of 40 males and 44 females with normal occlusion and aceptable profile. The results were obtained. 1) The tables of standard deviation from the measurements were made. 2) All linear measurement was greater in male than in female. 3) Female had more convex profile than male, 4) Facial convexity, upper and lower lip of esthetic line were gradually decreased with. age. 5) Upper incisor was gradually labioversioned with age.

• 대한치과교정학회지
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• 제5권1호
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• pp.11-19
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• 1975

This study was undertaken to investigate the exact values of the cephalometric standards of Hellman dental age III B groups of Korean in the reontgenocephalometry. The subjects consisted of 25 males and the same number of females with the normal occlusion and acceptable profile. Each lateral cephalometric head film was taken with the teeth in occlusion and the Focal-film distance was 300cm. Their linear and angular measurements were made directly. The following conclusions were obtained; 1) The author made the tables of standard deviation from the measured values. 2) The degree of the facial convexity of Korean children was larger than that of the white. 3) The labial inclination of the lower central incisor in male was a little greater than that in female.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.670-674
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• 1996

In automated search of a design database to support mechanical design, it is necessaryto recognize a shape pattern which represents a design object. This paper introduces the concept of a surface relation graph (SRG) for recognizing shape patterns from a 3D boundary representation scheme of a solid model(a B-rep model). In SRG, the nodes and arcs correspond to the faces and edges shared by two adjacent faces, respectively. An attribute assigned to an arc is given by an integer which discriminates the relationship between two adjacent faces. The + sign of the integer represents the geometric convexity of the solid, and the -sign the concivity at the shared edge. The input shape is recognized by comparison with the predefined features which are subgraphs of the SRG. A hierarchyof the database for upporting the design is presented. A search for the design database is also discussed. The usefulness of this method is illustrated by some application results.

• 한국CDE학회논문집
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• 제5권2호
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• pp.196-205
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• 2000

This paper proposes a topology-based algorithm for recognizing the passage features using a concept of multi-face hole loop. The Multi-face hole loop is a concetpual hole loop that is formed over several connected faces. A passage feature is recognized in the proposed approach by two multi-face hole loops that constitute its enterance and exit. The algorithm proposed in this paper checks the connectivity of the two multi-face hole loops to recognize passage features. The total number of passage features in a part is calculated from Euler equation and is compared with the number of found passage features to decide when to terminate. To find all multi-face hole loops in a part, this paper proposes an algorithm for finding all combinations of connected faces. The edge convexity is used to judge the validity of multi-face hole loops. By using the algorithm proposed in this paper, the passage features could be recognized effectively. The approach proposed in this paper is illustrated with several example parts.