• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.23-35
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• 1999

Lateral cephalograms or 251 males md 286 females were taken and pubertal growth pattern or cranial base, maxillary and mandible of 7 to 17 years old Korean children was evaluated. 10 landmarks and 16 analytical measurements were evaluated. Analytical measurement and annual difference for each age group was calculated and tested for statistical significance. Analytical measurements were classified into three groups which were cranial base, maxillary and mandibular measurements and also classified into make and female measurements. Following results were achieved. 1. The circumpuberal growth spurt was earlier in Korean females than in males. 2. Cranial base, maxilla and mandible showed circumpuberal growth. The cranial base showed a relatively smaller amount of growth than the facial complex. 3. Middle and posterior cranial base length showed a floater increase than anterior cranial base length and circumpuberal growth spurt was also more definite. 4. the forward and downward growth or maxilla results from maxillary growht itself and transposition or the maxilla due to circumsutural growth aroud the maxilla. Ar-ANS and Ar-Pr which represent maxillary position relative to the cranial base showed more growth than ANS-PNS which represents maxillary bone growth. 5. mandible showed more vertical growth than horizontal growth but without significance. 6. Alveolar gwoth of maxilla and mandible show maximum growth rate of the time of permanent teeth eruption following loss of deciduous teeth . After this period alveolar growth shows a decreasing tendency.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.355-365
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• 2000

The treatment plan for orthognathic surgery must be based on accurate predictions, and this can be produced the most esthetic results. Treatment of prognathic mandible in adult is usually orthognathic surgery using mandible set back, but mandible with retruded chin point is needed additional chin augmentation. In this case, the directions between mandible and chin point are different therefore, the prediction of soft tissue reactions must be modified. In this study, we materialize the patients who was taken orthognathic surgery due to prognathic mandible, 11each(Group A) was taken only Bilateral Sagittal Sprit Ramus Osteotomy (BSSRO), 9each(Group B) was taken additional advancement genioplasty. The lateral cephalometric radiography taken 8 months later after orthognathic surgery by this patients were used. The results of this study were as follows : 1. The profile of lips was favorable after surgery due to upper lip to I-line became prominent and lower lip tc E-line was retruded. 2. In both group, upper lip moved posteriorly and nasolabial angle was increased. 3. The ratio of the soft tissue profile change in POGs point to skeletal B point movement was $84\%$ in group A and $66\%$ in group B, and there was statistical significance between group A and group B. 4. Vertical movement of hard tissue points is decreased in group A.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1C
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• pp.43-52
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• 2006

Despite several constitutive models have been proposed and applied, it is still difficult to choose a suitable model and to estimate adequate analysis parameters. Furthermore, a cyclic shear behavior under the volume change caused by the seepage is more complex. None of the constitutive model is available at present in the expression of the cyclic behavior of soil under an additional volume change condition by seepage. Therefore, a new geotechnical hybrid simulation system which can control the pore water immigration was developed. The system enables a quantitative evaluation of the residual deformation such as lateral spreading and settlement caused by the liquefaction. The seismic responses in a one-dimensional slightly inclined multilayered soil system are taken into consideration, and the soils are governed by both equation of motion and the continuity equation. Furthermore, the estimation and the selection of the soil parameter for the representation of the strong nonlinearity of the material are not required, because soil behaviors under the earthquake motions are directly introduced instead of a numerical soil constitutive model. This paper presents the concept and specifications of the system. By applying the system to an example problem, the permeability effect on the seismic response during cyclic shear is studied. The importance of the volume change characteristics of sandy soil during and after cyclic shear is shown in conclusion.

• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.37-51
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• 2011

Geomorphic changes and sedimentary changes are investigated by sediment analysis from estuarine tidal flat, Mosan Bay Estuary, which is a tide-dominated and rias estuary. Sediments separatedly deposited during the early Holocene and the late Holocene. There are unconformities between the early Holocene sediment unit and the late Holocene sediment unit. Developments of these unconformities were related with fluctuated sea level change during the mid Holocene. Three deposit zones are spatially classified, which are named "intermittent tide channel deposit zone"(A1, B1, D3), "flood-dominated deposit zone"(A3, B3, C1, C3), and "fluvial sediment deposit zone"(A2, B2). This classification is explained by three main effects; laterally restricted migration of a tidal channel, diffract flood effect and settling lag effect, and fluvial induced reworking. These effects are deserved as main factors which have formed estuarine geomorphology in tidedominated and rias estuary. This study suggests research directions in reconstructing estuarine geomorphic and sedimentary change in west coast of Korea. Furthermore, it gives useful data for making a "land-ocean interaction" model for west coast of Korea.

• The korean journal of orthodontics
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• v.41 no.5
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• pp.324-336
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• 2011

Objective: The aim of this study was to conduct three-dimensional finite element analysis of individual tooth displacement and stress distribution when a posterior retraction force of 200 g was applied at different positions of the retraction hook on the transpalatal arch (TPA) of a molar, and over different lengths of the lever arm on the maxillary anterior teeth in lingual orthodontics. Methods: A three-dimensional finite element model, including the entire upper dentition, periodontal ligaments, and alveolar bones, was constructed on the basis of a sample (Nissan Dental Product, Kyoto, Japan) survey of Asian adults. Individual movement of the incisal edge and root apex was estimated along the x-, y-, and z-coordinates to analyze tooth displacement and von Mises stress distribution. Results: When the length of the lever arm was 15 mm and 20 mm, the incisal edge and root apex of the anterior teeth was displaced lingually, with a maximum lingual displacement at the lever arm length of 20 mm. When the posterior retraction hook was on the root apex, the molars showed distal displacement. When the length of the lever arm was 20 mm, anterior extrusion was reduced and the crown of the canine displaced toward the buccal side, in which case, the retraction hook was on the edge, rather than at the center, of the TPA. Conclusions: The results of the analysis showed that when 6 anterior teeth were retracted posteriorly, lateral displacement of the canine and lingual displacement of the incisal edge and root apex of the anterior teeth occur without the extrusion of the anterior segment when the length of the lever arm is longer, and the posterior retraction hook is in the midpalatal area.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.903-909
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• 2023

The purpose of this study is to compare and analyze the effect of changes in the patient's central position on the exposure dose and image quality of surrounding organs during a chest lateral examination using an Auto Exposure Control(AEC). The experiment was conducted on a human body phantom. A needle was attached to the lower part of the center of the coronal plane of the phantom, and a lead ruler was attached to the lower part of the detector so that the 50 cm point was located at the lower center of the AEC ion chamber. The exposure conditions were 125 kVp, 320 mA, the distance between the source and the image receptor was 180 cm, and the exposure field size was 14 × 17 inches. Only one AEC ion chamber was used at the bottom center, and the density was set to '0' and sensitivity to 'Middle', and the central X-ray was incident vertically toward the 6th thoracic vertebra. With AEC mode applied, the 50 cm point of the needle and lead ruler were aligned and the phantom was moved 5 cm toward the stomach (F5) and 5 cm toward the back (B5), and the dose factor was analyzed by measuring ESD. The ESD of the thyroid gland according to the change in patient center position was 232.60±2.20 μGy for Center, 231.22±1.53 μGy for F5, and 184.37±1.19 μGy for B5, and the ESD of the breast was 288.54±3.03 μGy for Center, F5 was 260.97±1.93 μGy, B5 was 229.80±1.62 μGy, and the ESD of the center of the lung was 337.02±3.25 μGy for Center, F5 was 336.09±2.29 μGy, and B5 was 261.76±1.68 μGy. As a result of comparing the average values of dose factors between each group, the difference in average values was statistically significant (p<0.01), and each group appeared to be independent. As a result of the study, there was no significant difference in the dose to the thyroid, breast, and center of the lung according to the change in the patient's central position, except for the breast (10%) when the patient moved forward about 5 cm. However, movement of about 5 cm posteriorly resulted in an average dose reduction of 23.7%. Additionally, when the patient's central position was moved to the rear, image quality deteriorated.

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.41-53
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• 2012

During rainfall period, to identify the characteristics of the infiltration of moisture, electrical resistivity monitering survey was carried out to weathered zone. Four regions of geophysical exploration areas with different rock types, four regions were selected. An area consists of mafic granite and three areas are composed of sedimentary rocks (Sandstone, Shale, Unconsolidated Mudstone). Survey was conducted from June (rainy season) to November (dry season), and during the period the change in resistivity was observed. According to the result of monitoring exploration on Geumjeong and Jinju areas, for the estimation of the standard rainfall, it is necessary to estimate the effects of the antecedent rainfall during the rainy season based on the overall rainfall from June till October and also necessary to consider this for the estimation of the half period. Also, the vertical distribution of the low resistivity anomaly zone does not show that the infiltration of moisture does not occur uniformly from the surface of the ground to the lower ground but shows that it occurs along the relaxed gap of the crack or soil stratum of the weathering zone. In Pohang area, the type of moisture infiltration is different from that of the granite or sedimentary rock. Since, after the rainfall, the rate of infiltration to the lower ground is high and the period of cultivation to the lower bedrock aquifer is short, it has similar effect to that of the antecedent rainfall applied for the estimation of the standard rainfall being presently used. In Danyang, due to the degree of water content of the ground, the duration period of the low resistivity anomaly zone observed in the lower ground of the place where clastic sedimentary rock is distributed is similar to that in Pohang area. The degree of lateral water diffusion at the time of localized heavy rain is the same as that of the sedimentary rock in Jinju. According to the above analysis results, in Danyang area, the period when the antecedent rainfall has its influence is estimated as three weeks or so.

• The korean journal of orthodontics
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• v.40 no.6
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• pp.398-410
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• 2010

Objective: The purpose of this study was to investigate the changes in dentofacial morphology of non-orthodontically treated female patients with TMJ disk displacement. Methods: The sample consisted of 25 Korean female patients with bilateral TMJ disk displacement who visited the Department of Orthodontics, Seoul National University Dental Hospital from 1996 to 2006. Disk displacements were diagnosed using the magnetic resonance imaging (MRI) of both TMJs. Baseline (T1) and follow-up (T2) lateral cephalograms were analyzed. The mean age of samples at T1 was $18.1{\pm}3.5$ years (range 14.2 - 25.8 years) and at T2, $21.1{\pm}3.5$ years (range 16.2 - 28.0 years). The mean observation period was $3.0{\pm}1.9$ years. Descriptive statistics for each variable were calculated at baseline (T1) and follow-up (T2) stages, and during the observation period (T2-T1). Results: Skeletal changes were found in 64% of the non-orthodontically treated female patients with TMJ disk displacement during the observation period. The L1 to Mandibular plane distance (mm) increased significantly by 0.8 mm (p < 0.01). But there were no significant differences in the other dental relationship variables (overjet, overbite, U1 to palatal plane) during the observation period. Most patients with skeletal changes showed a backward rotation of the mandible. The ratio of the rotation was a decrease of SNB by $0.43^{\circ}$ for every $1^{\circ}$ increase of FMA (Spearman rho = -0.660, P < 0.01). A few patients showed a distal shift of the mandible without rotation or significant changes in the vertical dimension. Conclusions: During observation periods without orthodontic treatment, non-growing patients with TMJ disk displacement showed dentoskeletal changes, mainly backward rotation of the mandible.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.649-661
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• 1999

The goals of this study were 1) to present pre-surgical naso-alveolar molding (PNAM) appliance for bilateral cleft lip and palate treatment and 2) to evaluate the effects of the PNAM appliance on the alveolar molding of the premaxilla and the lateral segments. Subjects consisted of 8 bilateral cleft lip and palate infants (7 males and 1 female, mean age at first visit = 61.6 days after birth) who were treated with PNAM appliances in Department of Orthodontics, Seoul National University Dental Hospital. Average alveolar cleft gap between the premaxilla and the lateral segment was $8.09{\pm}5.03mm$ and average duration of alveolar molding treatment was $8.8{\pm}3.1$ weeks. These patients' models were obtained at initial visit (T0) and after alveolar molding (T1). 20 linear and 14 angular variables were measured by using photometry and digital caliper, All statistical analyses were performed by Microsoft Excel 97 program. Paired t-test was used to discriminate the effect of alveolar molding by PNAM appliance. 1. Closure of the alveolar cleft gap in bilateral cleft cases by molding therapy was completed successfully, 2. Alveolar molding inhibited outward growth of lateral segments and produced inward bending of lateral segments. 3. By bending the anterior part of the vomer, the premaxilla could be rotated and moved. posteriorly via alveolar molding. Conclusion This appliance can be applied to bilateral cleft lip and palate infants with satisfactory results before cheiloplasty.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.3
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• pp.239-249
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• 2001

The purpose of this study is to evaluate the relationship of the factors which could be influenced by orthognathic surgery especillay SSRO. We measured the amounts of the maximum opening, lateral movements, maximum velocity and pattern of mandibular path during the opening and closing of mandible at the following times ; preoperative, 1 month after operation, 6 months after operation respectively using MKG. And the results were compared according to the categorized subgroups. Following results were obtained : 1. The change of the amounts of mandibular lateral movement and maximum opening velocity were statistically different between male and female (p<0.05), but the others were not. 2. According to the method of operation, there was no difference in the change of the mandibular movements between the group of SSRO and SSRO plus LeFort I osteotomy (p>0.05). 3. According to the amounts of mandibular movement, the recovery of left lateral movement of the group of $6{\sim}10mm$ was better than the other groups (p<0.05). 4. In the frontal pattern of the opening and closing of the mandible, the complex deflected type (F5), simple deflected type (F4), complex deviated type (F3), simple deviated type (F2), straight type (F1) were obtained in order at the time of preoperative, simple deflected type, simple deviated type, complex deviated type, straight type, complex deflected type in order at the time of 1 month after surgery, and the result at the time of 6 months after surgery was the same with that of the time of preoperative. In the sagittal pattern, non-coincident type (S2) was predominant at the time of preoperative, and coincident type (S1) was predominant at the time of 1 month after surgery. After 6 months, the result was also the same with that of the preoperative in sagittal pattern. 5. There was not a statistical difference in the change of the mandibular movement between group of presence of the preoperative TMJ symptoms and non-presence group (p>0.05). 6. There was not a statistical difference in the change of the mandibular movement between repositioning device applied group and non-applied group (p>0.05). 7. Sixty three percents of the patients who had preoperative TMJ symptoms were improved after surgery and preoperative TMJ symptoms were more improved after operation in the repositioning device non-applied group statistically (p<0.05).