• 대한치과보철학회지
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• 제42권4호
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• pp.458-470
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• 2004

Statement of problem: Br${\aa}$nemark or ITI are two currently most widely used implant systems but with contrasting design, surgical and restoration methods. Purpose: The purpose of this study was to compare changes and its statistical significance in bone height and shape which may rise due to the differences between two implant systems. Also to analyse the effect of inter-implant distance on annual bone height changes. Material & Method: Those patients who were treated with two or more of either Br${\aa}$nemark or ITI implants at posterior mandibular area at Yonsei University Dental Hospital, Implant Clinic were selected. At annual examination appointments, standardised radiographs using parallel technique were taken. Marginal bone and inter-implant crestal bone changes were measured and following results were obtained. Results: 1) When ITI and Br${\aa}$nemark system were compared, both annual marginal and inter-implant crestal bone height changes in ITI system in the first two years were smaller than Br${\aa}$nemark and they were statistically significant. On the third year, however, there was no statistical difference between two implant systems on their annual bone level changes (p>0.05). 2) The Marginal and inter-implant crestal bone changes were compared when inter-implant distance was less than 4mm. Statistically significant bone level changes were noted on the first year only for ITI implants but in the first and second year for Br${\aa}$nemark implants (p>0.05). 3) When comparing angulation changes between marginal bone and implant fixture, ITI system had smaller angulation changes but the annual changes were not statistically significant (p>0.05). Conclusion: Within the limitation of this study, it could be concluded that Br${\aa}$nemark implant systems had more changes in marginal and inter-implant crestal bone level in the first and second year after loading with statistical significance. Further studies are recommended to see the effects of these bone loss during the first and second year after loading on the long term prognosis of Br${\aa}$nemark Implants.

• 대한치과보철학회지
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• 제49권4호
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• pp.316-323
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• 2011

연구 목적: 본 연구의 목적은 치과용 임플란트 나사산 디자인이 변연골 응력에 미치는 영향에 정량적인 분석을 하고자 한다. 연구 재료 및 방법: 외경 4.1 mm (경부직경 3.5 mm), 매식부 길이 10 m인 표준형 ITI 임플란트 시스템(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland)을 기본모델(대조모델)로 채택하고, 그 몸체의 나사산은 다른 임플란트 시스템에 채택되고 있는 삼각형, 사각형, buttres형 디자인을 가지는 가상의 해석모델을 4종 만들었다. 해석모델은 나사산 형태와 크기에 따라 (1) 모델 A (작은 삼각형 나사산), (2) 모델 B (큰 삼각형 나사산), (3) 모델 C (buttres형 나사산), 및 (4) 모델 D (사각형 나사산)로 구분하였다. 유한요소 모델링과 해석에는 NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA) 프로그램을 사용하였다. Mesh 구성에는 NKTP type 34형 solid 요소(4각형 축대칭 요소, 요소당 절점수 8개)를 사용하여 임플란트 장축과 평행한 축대칭 하중은 물론 장축과 경사각을 갖는 비축대칭 하중조건을 모두 해석할 수 있도록 하였다. 임플란트의 표면으로부터 각각 0.2, 0.4, 0.6, 0.8, 1.0 mm 떨어진 위치에 5개의 응력관찰점(stress monitoring point)을 설정 하여 기록된 응력 값으로부터 회귀분석을 통하여 변연골 응력 최대값(peak stress)을 정량화하였다. 해석에 사용한 하중 조건은 2가지로, 임플란트 축에 평행한 수직하중 100 N과 임플란트 축과 $30^{\circ}$를 이루는 경사력 100 N 조건이었다. 결과: 임플란트 경부와 접하고 있는 인접 변연골에 응력집중현상이 보이고 있었으며, 그 양상은 임플란트 나사산 디자인과 무관하게 거의 유사하게 관찰되었다. 수직력 100 N 조건에서 산출된 변연골 최대응력값은 대조모델과 실험모델 A, B, C, D에서 7.84, 6.45, 5.96, 6.85, 5.39 MPa이었고, 경사력 조건에서는 각각 29.18, 26.45, 25.12, 27.37, 23.58 MPa이었다. 결론: 임플란트 나사산의 디자인은 변연골의 응력에 영향을 미치는 중요한 요소이다.

• Restorative Dentistry and Endodontics
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• 제26권4호
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• pp.316-325
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• 2001

The purpose of this study was to evaluate the effect of adhesive curing timing on the direction of polymerization shrinkage of light-curing composite resin. In this study, the curing times of adhesive and composite resin were measured by differential scanning calorimeter(DSC). 28 extracted human molars were embedded in clear resin and box-type cavities were prepared. Based on DSC data, the experimental teeth were divided into 4 groups. Group 1: no bond; Group 2: late curing; Group 3: Intermediate curing; Group 4: Early curing. After treating with adhesive, the buccal cavities were filled with Z-100 hybrid composite resin and the lingual ones were filled with AEliteflo flowable composite resin. The depressions at the surface were measured by surface profilometer, then the specimens were embedded in clear resin and sectioned. Impressions were obtained and used to get epoxy resin replicas. The epoxy replicas were gold-coated and observed under SEM. Average Maximum Gap(AMG), Gap Proportion(GP), Average Marginal Index(AMI) were used to compare the shrinkage gap of each group. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA, Student-Newman-Keuls method. The results of this study were as follows. 1. Average Maximum Gap, Gap Proportion, Average Marginal Index and depression at the surface or Z-100 hybride composite resin were smaller than those of AEliteflo flowable composite resin(P<0.05). 2. When the bonding between composite resin and tooth structure was strong, the shrinkage gap was small, and depression at the surface was deep(P<0.05). 3. In the well-bonded group, light-curing composite resin shrank toward bonded cavity wall, not toward light source. The result suggested that the direction of polymerization shrinkage was affected by the quality of bonding in the dentin-resin interface. The strong was the bonding between composite resin and tooth structure, the smaller was the gap and the deeper was the depression at the surface. Then the flow to compensate the polymerization shrinkage proceeded from surface to bonded cavity wall.

• The Journal of Advanced Prosthodontics
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• 제13권1호
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• pp.24-35
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• 2021

PURPOSE. This study was to evaluate the effect of rinsing time on the accuracy of interim crowns fabricated by digital light processing. MATERIALS AND METHODS. The maxillary right first molar master die was duplicated using a silicone material, while a study die was produced using epoxy resin. Scans of the epoxy resin die were used in combination with CAD software to design a maxillary right first molar interim crown. Based on this design, 24 interim crowns were fabricated with digital light processing. This study examined the trueness and precision of products that were processed with one of the three different postprocessing rinsing times (1 min, 5 min, and 10 min). Trueness was measured by superimposing reference data with scanned data from external, intaglio, and marginal surfaces. Precision was measured by superimposing the scan data within the group. The trueness and precision data were analyzed using Kruskal-Wallis, nonparametric, and post-hoc tests, and were compared using a Mann-Whitney U test with Bonferroni correction (α=.05). RESULTS. The trueness of the external and intaglio surfaces of crowns varied significantly among the different rinsing times (P=.004, P=.003), but there was no statistically significant difference in terms of trueness measurements of the marginal surfaces (P=.605). In terms of precision, statistically significant differences were found among the external, intaglio, and marginal surfaces (P=.001). CONCLUSION. Interim crowns rinsed for 10 minutes showed high accuracy.

• 대한치과보철학회지
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• 제46권2호
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• pp.169-174
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• 2008

목적: 치과 임플랜트 주위의 변연골 변화는 임플랜트의 기능적인 유지 뿐만 아니라 심미적 성공을 위해서도 중요하다. 변연골의 유지를 위한 임플랜트 디자인이 연구되고 있다. 이번 예비 연구는 두 종류의 external hex implant 시스템에서 임플랜트의 상부 미세 나사산이 변연골 변화량에 미치는 영향을 평가하고자 한다. 재료 및 방법: 총 24명의 환자를 대상으로 $Br{{\aa}}nemark$ 임플랜트 식립군 (1군, 거친 표면 임플랜트, 20개)과 원플란트 임플랜트 식립군 (2군, 미세나사산을 가진 거친 표면 임플랜트, 20개)으로 분류하였다. 기준 시점 (임플랜트 부하)과 부하를 가한 1년 뒤 임상적, 방사선학적 검사를 시행하였다. UTHSCSA Image Tool을 이용하여 임플랜트-보철 경계부로부터 변연골 높이 변화량으로 계측하였다. 계측치는 SAS 프로그램을 이용하여 three-level ANCOVA로 통계처리 하였다. 결과: 기준 시점과 비교하여 1년 기능 후, 두 그룹 간의 변연골 소실 변화량에 있어서 통계학적으로 유의한 차이가 있었다 (P<0.05). 1군의 평균 변연골 높이 변화량은 $0.83{\pm}0.31mm$, 2군에 있어서는 $0.44{\pm}0.36mm$ 이었다. 미세나사산을 가진 거친 표면 임플랜트가 미세나 사산을 가지지 않은 거친 표면 임플랜트 보다 더 적은 변연골 소실 변화량을 보였다. 결론: 미세나사산을 가진 거친 표면 임플랜트가 기능적 부하 후 변연골 높이를 유지하는데 있어 더 유리한 디자인으로 보인다.

• Journal of Nutrition and Health
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• 제26권5호
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• pp.593-602
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• 1993

As part of the Nutrition CRSP Mexico project conducted in rural villages in highland Mexico, this study examined whether nutritional factors, family characteristics, and the duration of schooling were associated with cognitive performances in 107 schoolers(53 boys and 54 girls) aged 8~10. Food intake was measured by recall, direct observation and weighment twice monthly over the course of a year. Families were characterized in terms of socioeconomic status and parental cognitive performance, education and aspiration. Dietary quality, but not energy intake, and anthropometry (wt-for-age, ht-for-age, head circumference) were significantly associated with cognitive test results for both verbal and performance measures. When the effect of SES is controlled using partial correlation, the relationships were substantially weakened. Sex differences were also found in response to nutritional deprivation. Among boys, dietary quality was the most important indicator of cognitive performance, while household economic conditions were more importantly associated with cognitive performance among girls. Participation in schooling was important for cognitive skille as it related to nutritional status.

• Communications for Statistical Applications and Methods
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• 제16권6호
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• pp.971-978
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• 2009

Poisson generalized linear mixed models(GLMMs) have been widely used for the analysis of clustered or correlated count data. For the inference marginal likelihood, which is obtained by integrating out random effects is often used. It gives maximum likelihood(ML) estimator, but the integration is usually intractable. In this paper, we propose how to obtain the ML estimator via Laplace approximation based on hierarchical-likelihood (h-likelihood) approach under the Poisson GLMMs. In particular, the h-likelihood avoids the integration itself and gives a statistically efficient procedure for various random-effect models including GLMMs. The proposed method is illustrated using two practical examples and simulation studies.

• East Asian Economic Review
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• 제22권2호
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• pp.141-176
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• 2018

The paper analyzes and compares the effects of domestic monetary policy using DSGE, DSGE-VAR, and VAR based on a two-country open economy model of Korea and the U.S. According to impulse response analysis, a domestic interest rate hike raises won value in the case of DSGE and DSGE-VAR models, while in the case of the unrestricted VAR model, it lowers won value. In the marginal data density standard, DSGE-VAR (${\mu}=1$) is superior to DSGE or Bayesian VAR over the sample period. Conversely, in the in-sample RMSE criterion, especially for the won/dollar exchange rate, VARs are superior to DSGE or DSGE-VAR. It is necessary to study further if these differences are caused by model misspecification or omitted variable bias.

• KDI Journal of Economic Policy
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• 제44권1호
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• pp.77-98
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• 2022

This paper empirically verifies that the types of capital adjustment costs serve as an important mechanism in relation to investment decision-making after confirming that the investment dispersion of Korean firms is pro-cyclical and can affect business cycles. Specifically, it is found through empirical methods using corporate financial data that capital adjustment costs generally assumed to take a quadratic form in macroeconomics are asymmetric and irreversible in the Korean economy. In particular, capital adjustment costs are empirically proven to cause investment dispersion to expand given that the substitution effect of the marginal value to the marginal cost for one unit of investment in the inter-temporal investment decision is affected by that cost with regard to the resale of owned equipment assets, as opposed to new investments in equipment assets. We ultimately show, albeit indirectly, that investment dispersion can affect business cycles as capital adjustment costs influences investment decisions. What is implied is that the capital adjustment cost is not merely an exogenously deep parameter that fits the dynamics of business cycles in a macroeconomic model but could instead be a policy variable that can be endogenized through government policies.

• 한국환경복원기술학회지
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• 제6권3호
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• pp.56-68
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• 2003

The main purpose of this study was to verify the shore margin protection effect of the root system of Salix gracilistyla Miq. developed from direct sticking cuttings on wetland, through the measurement of root growth and comparison of soil slaking rate depending on the planting method applied to shore-marginal slope. Comparison of growth rate and soil dispersion rate was made between five planted slope and one naked slope. The planting methods applied to the planted slope were (a) horizontally layed burying of stick(45cm) bundle (b) horizontally layed covering the slope with sticks (c) horizontally fencing with normal cuttings(20cm) (d) elected sticking of normal cutting at equal distances (e) random scattering short cuttings(3-4cm). As results, the most effective planting method was horizontally layed burying, and in order to increase its efficiency scattering the live stem chips in 2-3cm on the slope is recommended. The growth of root was negatively regressive to the distance from water floor.