• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.16 no.1
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• pp.69-79
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• 1986

The purpose of this investigation was to know correlation of mean values between centric occlusion and centric relation by the cephalogram in Angle's Class Ⅰ and Ⅲ malocclusion subjects. 22 adults with Angle's Class Ⅰ malocclusion (17 men and 5 women, 21 to 27 years of age) and 14 adults with Angle's Class Ⅲ malocclusion (10 men and 4 women, 21 to 27 years of age) were selected from the dental students in Yonsei University. Each subject was given two lateral cephalometric radiographies and cephalometric analysis was performed. All data from these analyses was recorded and statistically processed with CYBER computer system. 1. The results were obtained as follows: There was a strong positive correlation between centric occlusion and centric relation in all subjects with Angle's Class Ⅰ and Ⅲ malocclusion. 2. In Angle's Class Ⅰ malocclusion, measurements in lower facial height revealed significant difference between centric occlusion and centric relation (P<0.05). In Angle's Class Ⅲmalocclusion, measurements in facial axis angle, mandibular plane angle, convexity of A point, lower incisor protrusion, lower facial height revealed significant difference between centric occlusion and centric relation (P<0.05). 3. When the mandible was moved from centric occlusion to centric relation, the mean distance of mandibular movement was 1.27㎜ (0.2-2.8㎜) in Angle's Class Ⅰ malocclusion, 1.70㎜ (0.55-4.15㎜) in Angle's Class Ⅲ malocclusion, and 1.44㎜ (0.2-4.15㎜) in all subjects.

• Archives of Craniofacial Surgery
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• v.10 no.2
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• pp.81-85
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• 2009

Purpose: The inferior orbital wall is the most vulnerable to injury and inadequate reconstruction of inferior orbital fracture result in postoperative complications include enophthalmos, ocular dystopia and diplopia. Although the anatomical reconstruction of the inferior orbital wall is necessary to prevent these complications, the complexity of inferior orbital wall makes it difficult. We fabricated and remodeled the titanium micro-mesh plate for the anatomical reconstruction of inferior orbital wall. Methods: Twenty-nine patients with inferior orbital wall blow-out fracture were operated and twelve of them presented large extensive fracture. We intraoperatively fabricated and remodeled the Titanium-micro mesh to angulated lazy S shape similar to contralateral uninjured orbit. The preoperative and postoperative facial CT scan verified the 3-dimensional and anatomical reconstruction of the fractures. The mean follow-up was 19.7 months and postoperative complications was evaluated. Results: All cases showed the exact anatomical reconstruction, but there were minor complications in two cases. one patient had postoperative diplopia until 3months after surgery and the other patient had persistent enophthalmos (2 mm), but no further surgical correction was required. Conclusion: The comprehensive understanding of orbital convexity is the most important factor for anatomical reconstruction of inferior orbital fracture. We could prevent postoperative complications after inferior orbital wall reconstruction by intraoperative fabrication and anatomical remodeling of Titanium micro-mesh.

• The korean journal of orthodontics
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• v.22 no.3 s.38
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• pp.657-673
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• 1992

Orthodontic treatment of cleft patients is difficult as the growth is different from that of normal ones. So it is very important to know the characteristic features of the craniofacial morphology and growth pattern in unilateral cleft lip and palate patients. The materials for this study consisted of 55 normal males and 50 unilateral cleft lip and palate ones who received cheiloplasty and palatoplasty previously. The cleft subjects were divided into 4 groups according to their ages kto find out the growth pattern of hard and soft tissue, and to compare the features with those of normal ones. Each cephalogram analysed by McNamara method and others. The obtained results were as follows 1. In the unilateral cleft lip and palate subjects, forward growth of the maxilla was smaller than that of normal ones from 9 years old. So the maxilla was retruded. The maxillary incisors were severely retruded in all age groups. 2. The mandibular overall length and its anteroposterior position did not show any significant differences between two groups. But the height of ramus was very short and the mandible had vertical growth tendency to compensate for undergrowth of the maxilla in cleft subjects after 12 years of age. 3. Horizontal growth of the soft tissue in middle face was smaller than that of any other facial region from 9 years old. The vertical growth rate of upper lip was decreased as growing old. 4. In cleft subjects, the upper and lower facial component angle and the facial convexity angle were large. So their facial profile changed to straight or concave as growing old.

• The korean journal of orthodontics
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• v.43 no.3
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• pp.113-119
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• 2013

Objective: To compare three-dimensionally the midfacial hard- and soft-tissue asymmetries between the affected and the unaffected sides and determine the relationship between the hard tissue and the overlying soft tissue in patients with nonsyndromic complete unilateral cleft lip and palate (UCLP) by cone-beam computed tomography (CBCT) analysis. Methods: The maxillofacial regions of 26 adults (18 men, 8 women) with nonsyndromic UCLP were scanned by CBCT and reconstructed by three-dimensional dental imaging. The frontal-view midfacial analysis was based on a $3{\times}3$ grid of vertical and horizontal lines and their intersecting points. Two additional points were used for assessing the dentoalveolar area. Linear and surface measurements from three reference planes (Basion-perpendicular, midsagittal reference, and Frankfurt horizontal planes) to the intersecting points were used to evaluate the anteroposterior, transverse, and vertical asymmetries as well as convexity or concavity. Results: Anteroposteriorly, the soft tissue in the nasolabial and dentoalveolar regions was significantly thicker and positioned more anteriorly on the affected side than on the unaffected side (p < 0.05). The hard tissue in the dentoalveolar region was significantly retruded on the affected side compared with the unaffected side (p < 0.05). The other midfacial regions showed no significant differences. Conclusions: With the exception of the nasolabial and dentoalveolar regions, no distinctive midfacial hard- and soft-tissue asymmetries exist between the affected and the unaffected sides in patients with nonsyndromic UCLP.

• Journal of Korea Multimedia Society
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• v.3 no.3
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• pp.298-308
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• 2000

We present an efficient algorithm for finding the sequence of extreme vortices of a moving regular convex polyhedron of with respect to a fixed plane H.. The algorithm utilizes the spherical Voronoi diagram that results from the outward unit normal vectors nF$_{i}$ 's of faces of P. It is well-known that the Voronoi diagram of n sites in the plane can be computed in 0(nlogn) time, and this bound is optimal. However. exploiting the convexity of P, we are able to construct the spherical Voronoi diagram of nF$_{i}$ ,'s in O(n) time. Using the spherical Voronoi diagram, we show that an extreme vertex problem can be transformed to a spherical point location problem. The extreme vertex problem can be solved in O(logn) time after O(n) time and space preprocessing. Moreover, the sequence of extreme vertices of a moving regular convex polyhedron with respect to H can be found in (equation omitted) time, where m$^{j}$ $_{k}$ (1$\leq$j$\leq$s) is the number of edges of a spherical Voronoi region sreg(equation omitted) such that (equation omitted) gives one or more extreme vertices.

• Journal of Korean Neurosurgical Society
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• v.39 no.1
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• pp.20-25
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• 2006

Objective : The authors analyze prospectively the result of transcranial doppler[TCD] in normal pressure hydrocephalus and compared its cerebral blood flow parameters to radionuclide cerebrospinal fluid[CSF] flow study, postoperative brain computed tomography[CT] findings and clinical outcome, and studied the relationship between cerebral hemodynamics and clinical performance. Methods : Twenty five patients with hydrocephalus undertook pre- and post-operative TCD but only preoperative CSF flow study was performed. Mean flow velocity[Vm], pulsatility index[PI] and resistance index[RI] were assessed through TCD and changes in ventricle size and cortical gyral atrophy were checked through brain CT. Results : Postoperative hydrocephalus showed an increase in Vm[ACA P=0.037, MCA P=0.034], decrease in PI[ACA P=0.019, MCA P=0.017] and decrease in RI [ACA P=0.017, MCA P=0.021] compared to preoperative TCD parameters in the postoperative improvement group. In the postoperative improvement group, postoperative TCD parameters correlated with CSF flow study grade [Vm : $R^2=-0.75$, PI : $R^2=0.86$, RI : $R^2=0.78$] and ventriculocranial ratio change correlated with PI change [$R^2=0.73$]. The convexity gyral atrophy and initial TCD parameters showed close relationship to outcome. Conclusion : PI and RI can be used as an indicator of post operative prognosis, and with the addition of CSF flow study values, can also be used as a tool to predict pre-op and post-op patient status and successful shunt surgery.

• The KIPS Transactions:PartA
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• v.14A no.7
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• pp.435-442
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• 2007

This paper is concerned with the mesh segmentation problem that can be applied to diverse applications such as texture mapping, simplification, morphing, compression, and shape matching for 3D mesh models. The mesh segmentation is the process of dividing a given mesh into the disjoint set of sub-meshes. We propose a method for segmenting meshes by simultaneously reflecting global and local geometric characteristics of the meshes. First, we extract sharp vertices over mesh vertices by interpreting the curvatures and convexity of a given mesh, which are respectively contained in the local and global geometric characteristics of the mesh. Next, we partition the sharp vertices into the $\kappa$ number of clusters by adopting the $\kappa$-means clustering method [29] based on the Euclidean distances between all pairs of the sharp vertices. Other vertices excluding the sharp vertices are merged into the nearest clusters by Euclidean distances. Also we implement the proposed method and visualize its experimental results on several 3D mesh models.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.661-666
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• 2017

Objective : Atypical meningioma is rare tumor and there is no accurate guide line for optimal treatment. This retrospective study analyzed the prognostic factors, the effect of different methods of treatments and the behavior of atypical meningioma. Methods : Thirty six patients were diagnosed as atypical meningioma, among 273 patients who were given a diagnosis of meningioma in the period of 2002 to 2015. Age, gender, tumor location, Ki 67, Simpson grade and treatment received were analyzed. We studied the correlation between these factors with recurrence, overall survival rate and progression free survival. Results : Median overall survival time and progression free survival time are 60 and 53 (months). Better survival rate was observed for patients less than 50 years old but with no statistical significance (p=0.322). And patients with total resection compared with subtotal resection also showed better survival rate but no statistical significance (p=0.744). Patients with a tumor located in skull base compared with patients with a tumor located in brain convexity and parasagittal showed better progression free survival (p=0.048). Total resection is associated with longer progression-free survival than incomplete resection (p=0.018). Conclusion : We confirmed that Simpson grade was significant factor for statistically affect to progression free survival in univariate analysis. In case of skull base atypical tumor, it is analyzed that it has more recurrence than tumor located elsewhere. Overall survival was not affected statistically by patient age, gender, tumor location, Ki 67, Simpson grade and treatment received in this study.

• The korean journal of orthodontics
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• v.46 no.6
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• pp.356-363
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• 2016

Objective: The additional arch length required for leveling (AALL) the curve of Spee (COS) can be estimated by subtracting the two-dimensional (2D) arch circumference, which is the projection of the three-dimensional (3D) arch circumference onto the occlusal plane, from the 3D arch circumference, which represents the arch length after leveling the COS. The purpose of this study was to determine whether the cusp tips or proximal maximum convexities are more appropriate reference points for estimating the AALL. Methods: Sixteen model setups of the mandibular arch with COS depths ranging from 0 mm to 4.7 mm were constructed using digital simulation. Arch circumferences in 2D and 3D were measured from the cusp tips and proximal maximum convexities and used to calculate the AALL. The values obtained using the two reference points were compared with the paired t -test. Results: Although the 3D arch circumference should be constant regardless of the COS depth, it decreased by 3.8 mm in cusp tip measurements and by 0.4 mm in proximal maximum convexity measurements as the COS deepened to 4.7 mm. AALL values calculated using the cusp tips as reference points were significantly smaller than those calculated using the proximal maximum convexities (p = 0.002). Conclusions: The AALL is underestimated when the cusp tips are used as measurement reference points; the AALL can be measured more accurately using the proximal maximum convexities.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.6
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• pp.606-612
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• 2000

This study was performed to investigate the average anthropometric value of normal Korean men and women and to compare the preceding literatures. Additionally, average Korean profilogram was made to serve as a template for diagnosis of facial form. Eighty five Korean subjects(41 men, 44 women) aged between 21 to 26 were selected by members of the author's department on the basis of intact dentition and Class I occlusion without facial asymmetry. Frontal and lateral photographs were taken under standardized condition with digital camera. The image was magnified and adjusted according to the FH plane of cephalometric radiographs and digitized using personal computer. To compare the Western beauty, 25 esthetically pleasing female was selected to measure various angle and distance of the face. 1. It was possible to calculate the mean coordinate value of Korean normal samples which enables the direct visualization and comparison with the use of template. The method in this study was easy to applicate under the Microsoft $Windows^{(R)}$ bases. 2. Maxillary vertical hypoplasia, upper and lower lip protrusion was characteristics of Korean norms and relatively narrow alar base distance, less conspicuous nasal projection was observed. As the vermilion exposure and upper lip length was more than western norm, chin looks shorter than western. To compare the Korean and Western esthetically pleasing profile, facial convexity and nose was less conspicuous in Korean women.