• Journal of the Korean Geotechnical Society
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• v.15 no.4
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• pp.207-220
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• 1999

Model tests were performed to investigate the failure modes in embankments on soft ground supported by piles with cap beams. In the model tests, Jumunjin standard sand was placed on simulated cap beams and soft ground. The cap beams are placed perpendicular to the longitudinal axis of the embankment. The colored sand and the Jmniin standard sand were placed one after the other above cap beams and soft ground to make lateral stripes with 3mm thickness in the embarkment. The colored sand was prepared by coating the Jumunjin sand with black lead powder. The photographs illustrate the two characteristic modes of failure in embarkments. One is the soil arching failure and the other is the punching shear failure. The failure mode depends on the height of embankment and the space between cap beams. That is, if the embankment is high enough compared with the space between cap beams, it will fail in arching failure. On the other hand if the embarkment is relatively low or the space between piles is too wide, it will fail in punching shear failure. The soil arching develops in embarkment as a semicylindrical arch with a thickness equal to the width of the cap beam. And the soil wedge developed above the cap beams remains intact during both arching and punching failures. The boundary of punching shear failure of the displaced soil mass can be defined on the basis of observation of the photographs.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.167-175
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• 2020

The purpose of this study was to determine whether the palatal rugae could be used as an appropriate reference area for serial model superimposition following Rapid maxillary expansion(RME) and facemask treatment. A total of 52 pediatric patients who had undergone RME and facemask treatment were selected. Palate and palatal rugae in the pre- and post- treatment casts from the patients were measured. In spite of dentoalveolar changes occurred by RME and facemask, anteroposterior changes in palate and palatal rugae were not significant. Anatomical changes of palate and palatal rugae were mostly shown in the transverse dimension. The soft tissue of the palatal rugae stretches in adaptation to hard tissue movement. Among the evaluated landmarks, the medial point of the third palatal rugae seemed to be the most stable. The observed alterations in the palatal rugae demonstrated the potential of medial points of third palatal rugae as a reference point in model superimpositions to evaluate dental movement within the maxillary arch following RME and facemask treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.4
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• pp.206-213
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• 2019

Purpose: Most of studies dealing with abfractions are limited to the buccal surfaces of the teeth. In this study, we analyzed the cause for abfraction by investigating the incidence of palatal side abfractions in maxillary posterior teeth. Materials and Methods: We investigated a total of 3193 maxillary posterior teeth by an intraoral examination, model observation, and observation of virtual model fabricated using model scanning. We recorded the results and classified them depending on the type of teeth, age, gender, and side of arches. We also performed Chi-square test to evaluate the statistical significance among the groups (α = 0.05). Results: The incidence of palatal side abfraction of the maxillary molars (10.8%) was higher than the premolars (6.8%), and among them, the incidence of the 1st molars (39.1%) were the highest. The incidence of palatal side abfraction increased with age and was statistically significant (P < 0.05). There was no statistical significance in the difference by gender (P > 0.05); in the case of arches, left arch showed higher incidence and it was statistically significant (P < 0.05). Conclusion: Palatal side abfraction in maxillary posterior teeth was frequently observed in the maxillary 1st molars, and the incidence increased with age. This result suggests that the main reason for abfraction is due to occlusal force.

• International Area Studies Review
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• v.13 no.3
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• pp.287-308
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• 2009

This article examines the distributional characteristics of the return of Chinese stock market indices. The majority of previous empirical researches have tended to focus upon the simple stock market index. However, this study focuses on the four indices which represent the characteristics of each stock market index. The empirical findings indicate that the returns of the four chinese indices are not normally distributed at conventional levels. The Ljimg-Box -statistics indicate the returns of the index of A shares are not serially autocorrelated. However, the returns of the index of B shares are serially autocorrelated. The empirical findings also indicate returns of the four chinese indices are not serially autocorrelated. The statistics of Regression Specification Error Test and ARCH indicate the returns of all four indices are not serially linear. The findings also indicate that E- GARCH model is the most fittest model for the returns of the four chinese indices and the forecast error can be reduced by using student t distribution rather normal distribution.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.93-98
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• 2017

PURPOSE. The purpose of this study was to compare the width ratio of maxillary anterior teeth according to age in the Korean population and to evaluate the maxillary central incisor width-to-length (W/L) ratio, given differences in age and gender. MATERIALS AND METHODS. Ninety-three Korean adults were divided into 3 groups (n = 31) by age. Group I was 20 - 39 years old, Group II was 40 - 59 years old, and Group III was over 60 years of age. After taking an impression and a cast model of the maxillary arch, the anterior teeth width ratio and central incisor W/L ratio were calculated from standard digital images of the cast models using a graph paper with a digital single lens reflex (DSLR) camera. The calculated ratios were compared among all groups and central incisor W/L ratio were analyzed according to age and gender. All comparative data were statistically analyzed with one-sample t-tests, one-way ANOVAs with Tukey tests, and independent t-tests. RESULTS. No significant differences in maxillary anterior teeth ratios were found among the age groups. The maxillary central incisor W/L ratios in Group III were the greatest and were significantly higher than those in the other groups. The central incisor W/L ratio of men was higher than that of women in Group II. CONCLUSION. Maxillary anterior teeth width ratios were similar in all age groups in the Korean population. The maxillary central incisor was observed as worn teeth in the group over 60 years of age, and a significant difference between genders was found in 40 to 50 year olds.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.6
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• pp.333-343
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• 2018

In this paper, we study the existing results of the structure-soil-structure interaction (SSSI) effect on seismic responses of structures and summarize important parameters. The parameters considered in this study are a combination of buildings in the power block of a nuclear power plant, the characteristics of earthquake ground motions and its direction, and the characteristics embedded under the ground. Based on these parameters, the seismic analysis model of the structures in the power block of the nuclear power plant is developed and the structure-soil-structure interaction analyses are performed to analyze the influence of the parameters on the seismic response. For all analyses, the soil-structure interaction (SSI) analysis program CNU-KIESSI, which was developed to enable large-sized seismic analysis, is used. In addition, the SSI analyses is performed on individual structures and the results are compared with the SSSI analysis results. Finally, the influence of the parameters on the seismic response of the structure due to the SSSI effect is reviewed through comparison of the analysis results.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.3
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• pp.328-342
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• 1999

This study was performed to investigate the factors related to tooth wear. For this study, 78 patients with temporomandibular disorders and 76 dental students without any signs and symptoms of temporomandibular disorders were selected as the patients group and as the normal group, respectively. Preferred chewing side, Angle's classification, lateral guidance pattern, head and shoulder posture were observed clinically. Electromyographic activity of anterior temporalis and masseter muscle were recorded with $BioEMG^{(R)}$ and occlusal status were recorded with $T-Scan^{(R)}$. Wear facet area of each tooth was measured from working model of upper arch corresponding to the occlusal status from T-Scan. Wear facet area were measured with planimeter in $mm^2$. Total area were divided into incisal, canine, posterior tooth area. Anterior wearfacet area was incisor area plus canine area, and unilateral area was anterior area plus posterior area. The data collected were analyzed by SAS statistical program and the results of this study were as follows: 1. There was no significant difference between the two groups in total werafacet area, and male subjects showed tendency to have larger area in the normal group but female subjects showed tendency vice versa. 2. There was no significant difference related to preferred chewing side and Angle's classification, however some difference was observed by lateral guidance pattern. Anterior wear facet area in subjects of canine guidance was the largest in the three subgroups. 3. Subjects with head tilting to right side had larger posterior and total area, and subjects with higher shoulder in right side had larger canine and anterior area than any other subgrous. 4. Electromyographic activity of masseter muscle was more correlated with wear facet area than anterior temporalis muscle, and tooth contact number and force were significantly correlated with wear facet area, but the most important factor affecting tooth attrition was age.

• The korean journal of orthodontics
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• v.47 no.1
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• pp.21-30
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• 2017

Objective: The aim of this study was to investigate the three-dimensional (3D) position of the center of resistance of 4 mandibular anterior teeth, 6 mandibular anterior teeth, and the complete mandibular dentition by using 3D finite-element analysis. Methods: Finite-element models included the complete mandibular dentition, periodontal ligament, and alveolar bone. The crowns of teeth in each group were fixed with buccal and lingual arch wires and lingual splint wires to minimize individual tooth movement and to evenly disperse the forces onto the teeth. Each group of teeth was subdivided into 0.5-mm intervals horizontally and vertically, and a force of 200 g was applied on each group. The center of resistance was defined as the point where the applied force induced parallel movement. Results: The center of resistance of the 4 mandibular anterior teeth group was 13.0 mm apical and 6.0 mm posterior, that of the 6 mandibular anterior teeth group was 13.5 mm apical and 8.5 mm posterior, and that of the complete mandibular dentition group was 13.5 mm apical and 25.0 mm posterior to the incisal edge of the mandibular central incisors. Conclusions: Finite-element analysis was useful in determining the 3D position of the center of resistance of the 4 mandibular anterior teeth group, 6 mandibular anterior teeth group, and complete mandibular dentition group.

• The Korean Journal of Applied Statistics
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• v.24 no.6
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• pp.1033-1043
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• 2011

In this paper, we use a nested family of models of Generalized Autoregressive Conditional Heteroscedasticity(GARCH) to verify asymmetric conditional heteroscedasticity in the KOSPI and Won-Dollar exchange rate. This study starts from an investigation of whether time series data have asymmetric features not explained by standard GARCH models. First, we use kernel density plot to show the non-normality and asymmetry in data as well as to capture asymmetric conditional heteroscedasticity. Later, we use three representative asymmetric heteroscedastic models, EGARCH(Exponential Garch), GJR-GARCH(Glosten, Jagannathan and Runkle), APARCH(Asymmetric Power Arch) that are improved from standard GARCH models to give a better explanation of asymmetry. Thereby we highlight the fact that volatility tends to respond asymmetrically according to positive and/or negative values of past changes referred to as the leverage effect. Furthermore, it is verified that how the direction of asymmetry is different depending on characteristics of time series data. For the KOSPI and Korean won-US dollar exchange rate, asymmetric heteroscedastic model analysis successfully reveal the leverage effect. We obtained predictive values of conditional volatility and its prediction standard errors by using moving block bootstrap.

• Journal of Chest Surgery
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• v.32 no.6
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• pp.504-509
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• 1999

Background: Heart transplantation is considerated for a selected certain group of complicated congenital heart disease in neonates because corrective surgery is very difficult and has high mortality. Precise planning of transplantation is necessary to adequately fit the donor heart to the recipient. Material and Method: We have performed 4 neonatal pig heart transplantations to test the technical feasibility. Experiment 1: The transplantation was performed using the same technique as the adult heart transplantation. Experiment 2: The transplantation for hypoplastic left heart syndrome was simulated as we reconstructed the whole aortic arch with donor aorta. Experiment 3: The heart transplantation was done with radical pulmonary artery reconstruction. Experiment 4: The experiment was performed for a long term survival. Result: Preoperative planning was very important for adequate fitting. All animals could be weaned from cardiopulmonary bypass, however, two animals died due to bleeding at pulmonary artery and left atrium. Conclusion: We concluded that the neonatal heart transplantation can be applied in some complicated Further using animal model is mandatory.