• 대한치과보철학회지
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• 제43권5호
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• pp.611-621
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• 2005

State of problem: Zirconia all-ceramic restoration fabricated with CAM system is on an increasing trend in dentistry. However, evaluation of the marginal and internal fits of zirconia bridge seldomly have been reported. Purpose: This study was to evaluate the at of margin and internal surface in posterior 3-unit zirconia bridge framework fabricated with CAM system(DeguDent, Germany). Material and Method: Preparations of secondary premolar and secondary molar on artificial resin model were performed for fabrication of 3-unit posterior bridge framework. Fits of 5 zirconia bridge framework were compared with 5 precious ceramo-metal alloy framework(V-GnathosPlus, Metalor, Switzerland), and prepared margins were designed to chamfer and shoulder finishing line. Each framework was cemented to epoxy resin model with reinforced glass ionomer(FujiCEM, GC Co., Japan), embedded in acrylic resin and sectioned in two planes, mesio-distal and buccolingual. Samples were divided into six pieces by sectioning and had two pieces of each surface(i.e mesial, distal, buccal and lingual surface) per abutment, so there were eight measuring points in each abutment. External gap was measured at the margin and internal gaps were measured at the margin, axial and occlusal surface. Gaps were observed under the measuring microscope(Compact measuring microscope STM5; Olympus, Japan) at a magnification of $\times100$. T-test were used to determine the statistic significance of the different gaps between zirconia and metal framework. Results and Conclusion: 1. External and internal marginal gaps of zirconia and metal framework were in clinically acceptable range. External marginal gaps were not different significantly between zirconia$(81.9{\mu}m)$ and metal $(81.3{\mu}m)$ framework and internal marginal gaps of zirconia $(44.6{\mu}m)$ were smaller than those of metal framework $(58.6{\mu}m)$. 2. Internal axial gaps of zirconia framework$(96.7{\mu}m)$ were larger than those of metal frame-work$(78.1{\mu}m)$ significantly and adversely, internal occlusal gaps of zirconia frame-work$(89.4{\mu}m)$ were smaller than those of metal framework $(104.9{\mu}m)$ significantly. 3. There were no significant differences in external and internal marginal gaps between chamfer and shoulder finish line when zirconia frameworks were fabricated.

• 기록학연구
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• 제43호
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• pp.43-70
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• 2015

최근 정치엘리트에 관한 구술연구가 급속히 증대되고 있다. 문제는 엘리트 구술연구에서 수집된 자료들의 가치가 의심받고 있다는 점이다. 의도적이든 비의도적이든 간에 정치엘리트의 구술자료는 그 자료가 설명하고자 하는 사실과 거리(간극)가 크다는 이유 때문이다. 이 논문의 목적은 이러한 간극을 분석하고, 그에 대한 해결책을 제시하는 것이다. 사실 엘리트 구술자료에서 나타나는 간극은 하나가 아니다. 그것은 구술자료가 생산되는 과정에서 발생하며, 질적으로 상이한 여러 가지 유형으로 구분할 수 있다. 제1유형의 간극은 기억이 형성되는 과정에서 발생하는 간극이다. 구술자들이 외부의 객관적인 사실을 선별적으로 인식하고 기억하기 때문에 발생한다. 선별인식, 선별기억, 개별적 경험 등이 이 경우에 해당한다. 이러한 간극은 단순한 오류와 구별된다. 이 유형의 간극은 그 자체로 하나의 사실이며, 분석대상이 되어야한다. 제2유형은 기억을 유지하는 과정에서 발생하는 간극이다. 한번 형성된 기억은 시간이 지나면서 마모되거나 변형되기 때문에 발생하는 간극이다. 망각이나 기억변형이 이 경우에 해당한다. 구술자에게서 이러한 간극이 왜 발생하였는가를 이해할 수 있다면, 그 간극을 해석하고 좁히는데 도움이 된다. 제3유형은 구술하는 과정에서 발생하는 간극이다. 구술자가 자신의 기억과 다른 내용을 진술함에 따라 나타나는 간극이다. 의도적인 허위진술이나 반복적인 허위진술이 여기에 해당한다. 구술사 연구에서 피하거나 제거해야할 간극이다. 본 논문의 결론은 다음과 같다. 첫째, 모든 간극을 부정적으로 볼 필요는 없다는 것이다. 제1유형과 제2유형 간극은 구술자료가 지니고 있는 단점이라기보다는 장점이라 할 수 있다. 이 간극들을 해석함으로써 사실을 보다 풍부하게 이해 할 수 있기 때문이다. 둘째, 부정적인 간극인 제3유형의 간극은 구술을 준비하는 과정, 구술을 진행하는 과정, 구술자료를 해석하는 과정에서 좁힐 수 있다는 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.795-800
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• 2000

A CCFL(Counter Current Flow Limit) test have been performed in narrow annular gaps with large diameter, because it has been confirmed that the CCFL phenomena affected the critical power in hemispherical narrow gap geometries from the SONATA(Simulation Of Naturally Arrested Thermal Attack)-IV (In-Vessel)/VISU(Visualization)-II experiments. The objectives of the CCFL experiments are to investigate the small gap sizes(1, 2mm) effect on CCFL under the large diameter condition and to confirm the findings of the VISU-II study that global dryout in hemispherical narrow gaps was induced by the CCFL. The test section was made of acrylic resin to allow visual observation on the two-phase flow behaviors inside annular gaps. It was observed from visualization that a part of water supplied was accumulated in the upper plenum and a significant increase in the differential pressure across the gap was occurred, which was the definition of the CCFL occurrence in this experimental study. From the experimental results in annular gap with large diameter it can be known that an increase in the differential pressure was not big at small air flow-rates. When the CCFL was occurred, the differential pressure across gaps was increased significantly and a water accumulated in the upper plenum. The occurrence of CCFL was correlated using the Wallis parameter.

• 응용통계연구
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• 제25권4호
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• pp.621-632
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• 2012

Recurrent event data can be easily found in longitudinal studies such as clinical trials, reliability fields, and the social sciences; however, there are a few observations that disappear temporarily in sight during the follow-up and then suddenly reappear without notice like the Young Traffic Offenders Program(YTOP) data collected by Farmer et al. (2000). In this article we focused on inference for a cumulative mean function of the recurrent event data with these incomplete observation gaps. Defining a corresponding risk set would be easily accomplished if we know the exact intervals where the observation gaps occur. However, when they are incomplete (if their starting times are known but their terminating times are unknown) we need to estimate a distribution function for the terminating times of the observation gaps. To accomplish this, we treated them as interval-censored and then estimated their distribution using the EM algorithm proposed by Turnbull (1976). We proposed a nonparametric estimator for the cumulative mean function and also a nonparametric test to compare the cumulative mean functions of two groups. Through simulation we investigated the finite-sample performance of the proposed estimator and proposed test. Finally, we applied the proposed methods to YTOP data.

• 대한치과기공학회지
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• 제42권3호
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• pp.197-201
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• 2020

Purpose: This study aimed to assess the quality of dental prostheses printed by digital light-processing (DLP) technology. Methods: Ten experimental models were prepared. The ten specimens that were printed by DLP technology constituted the DLP group. The ten specimens that were produced in the same model by the casting method constituted the control group. The marginal gaps of the 20 specimens produced were measured. These gaps were measured by a silicon replica technique at two abutments of the specimen. Therefore, 20 marginal gaps were measured in each group. An independent sample t-test was performed to compare the marginal gaps measured in the two groups (α=0.05). Results: According to the results of the measurement, there was a significant difference between the mean marginal gap of the control group (78.8 ㎛) and that of the DLP group (91.5 ㎛), p<0.001. Conclusion: Although the mean marginal gaps of dental fixed prostheses produced by the DLP method was higher than the mean marginal gap of those produced by the casting method, it was considered to be within the clinical threshold value suggested by some previous studies.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.275-278
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• 2012

We investigate the interaction between the propagation of detonation and inserted gaps in the high explosive. The Eulerian-based multi-material simulation code validated through comparison with experimental results was used. A series of gap materials is used to understand the detonation propagation characteristic in the presence of multiple gaps.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.578-581
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• 2007

Microplasma modes generated in a display cell with an auxiliary electrode were investigated in accordance with various coplanar-gaps and plategaps. At plate-gaps shorter than the coplanar-gap, the mode transition voltage of the auxiliary pulse increased with an increase in the coplanar-gap. At longer plate-gaps, the mode transition voltage of the auxiliary pulse decreased with an increase in the coplanar-gap.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1996년도 한국생물과학협회 국제학술대회
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• pp.103.2-103
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• 1996

No Abstract, See Full Text

• 한국수소및신에너지학회논문집
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• 제31권3호
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• pp.328-336
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• 2020

In the Francis turbine, the leakage flow through the runner gaps which are between the runner and the stator structure influences the internal flow and hydraulic performance. Thus, the investigation for the flow characteristics induced by the runner gaps is important. However, the runner gaps are often disregarded by considering the time and cost of the numerical analysis. Therefore, in this study, the flow characteristics according to runner gaps of the Francis turbine model were investigated including the leakage flow of the runner cone. The three-dimensional unsteady Reynolds-averaged Navier-Stokes analyses were conducted using a scale-adaptive simulation shear stress transport as a turbulence model for observing the influence of the leakage flow on the internal flow and hydraulic performance. The efficiencies were decreased slightly with runner gaps; and the complicated flows were captured in the gaps.

• 한국컴퓨터정보학회논문지
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• 제19권1호
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• pp.119-130
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• 2014

본 논문은 다양한 네트워크를 편리하게 분석할 수 있는 실용적인 유전 알고리즘 기반 경로탐색 시스템인 GAPS를 제안하고자 한다. 이러한 목적을 위해 GAPS는 네트워크 모델링을 위한 직관적인 그래픽 사용자 인터페이스와 모델링 및 탐색 과정에서 발생하는 데이터들을 관리하기 위한 데이터베이스 관리 시스템, 다양한 네트워크를 분석하기 위해 개발된 간단한 유전 알고리즘을 결합하여 개발되었다. 특히, 기존의 유전 알고리즘들이 단락이 많고 두 개 노드 간 실행가능 경로 수가 많지 않은 네트워크를 분석하는데 적합하지 않았던 반면, GAPS는 실행가능 경로와 실행불가능 경로를 모두 적절히 평가할 수 있는 적합도 함수를 사용하는 유전 알고리즘에 기반하고 있어 해 집단의 다양성을 유지하면서 다양한 네트워크들을 분석할 수 있다. 실험결과, GAPS를 통해 단락이 많은 네트워크와 단락이 적은 네트워크를 모두 편리하게 분석할 수 있다는 점과, GAPS가 기존의 경로탐색문제를 위한 유전 알고리즘들과 대비되는 장점을 갖고 있음을 확인할 수 있었다.