• The Journal of Advanced Prosthodontics
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• 제11권5호
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• pp.271-279
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• 2019

PURPOSE. The newest technologies for digital implant impression (DII) taking are developing rapidly and showing acceptable clinical results. However, scientific literature is lacking data from clinical studies about the accuracy of DII. The aim of this study was to compare digital and conventional dental implant impressions (CII) in a clinical environment. MATERIALS AND METHODS. Twenty-four fixed zirconia restorations supported by 2 implants were fabricated using conventional open-tray impression technique with splinted transfers (CII group) and scan with Trios 3 IOS (3Shape) (DII group). After multiple verification procedures, master models were scanned using laboratory scanner D800 (3Shape). 3D models from conventional and digital workflow were imported to reverse engineering software and superimposed with high resolution 3D CAD models of scan bodies. Distance between center points, angulation, rotation, vertical shift, and surface mismatch of the scan bodies were measured and compared between conventional and digital impressions. RESULTS. Statistically significant differences were found for: a) inter-implant distance, b) rotation, c) vertical shift, and d) surface mismatch differences, comparing DII and CII groups for mesial and distal implant scan bodies ($P{\leq}.05$). CONCLUSION. Recorded linear differences between digital and conventional impressions were of limited clinical significance with two implant-supported restorations.

• 소성∙가공
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• 제26권1호
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• pp.28-34
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• 2017

Multi-pass shape rolling is performed to produce long products of arbitrary cross-sectional shapes. In the past, the multi-pass shape rolling process has been designed by the trial and error method or the experience of experts based on the empirical approach. Particularly, the design of roll caliber in shape rolling is important to improve product quality and dimensional accuracy. In this paper, the caliber design and pass schedule of multi-pass shape rolling were proposed for manufacturing piston ring wire. In order to design roll caliber, major shape parameter and dimension was determined by analysis of various caliber design. FE-simulation was conducted to verify effectiveness of proposed process design. At first, forming simulation was performed to predict shape of the product. Then, fracture of the wire was evaluated by critical damage value using normalized Cockcroft-Latham criteria. The experiment was carried out and the results are within the allowable tolerance.

• 대한조선학회논문집
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• 제39권2호
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• pp.28-33
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• 2002

조선소에서 사용되는 선각 외판 부재는 선박 한 척을 건조하는데 사용되는 부재의 수가 매우 많고, 각 가공 외판 부재는 상대적으로 크기가 크고 각각 상이한 부재 형상을 가지고 있다는 특징이 있다. 또한 이 중에서, 선체의 외판 곡 부재를 가공할 때는 각 부재의 초기 형상과 가공 목적형상에 대한 정보를 가지고 냉간, 열간 가공을 통하여 설계된 형상으로 가공을 수행하여야 한다. 이때, 최초 가공 시 및 추가 가공 중에 부재의 형상을 확인하여 주어진 정도에 부합할 때까지 가공을 수행 하여야 하며, 이와 같은 특징 때문에 선체 외판 부재의 가공 시에는 수시로 가공중인 부재의 형상 및 가공정도를 확인하여야 하는 과정, 즉 시간을 최소화하면서 효율적으로 가공형상을 확인하는 대형곡면 계측 기술과, 곡면 비교 기술이 필요하게 된다. 본 논문에서는, 이러한 가공환경 하에서 적용 가능성이 있는 효율적인 계측, 비교를 위한 S/W, H/W 통합 시스템 구축을 수행하였다.

• 한국항행학회논문지
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• 제10권4호
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• pp.385-393
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• 2006

본 논문에서는 2.45GHz 대역 RTLS 환경에서 탐색범위 확장을 고려한 위치추정 알고리즘을 제안하고 평균 추정오차 성능을 분석하였다. 확장 가능한 탐색범위는 $300m{\times}300m$, 2차원 평면상의 정사각형으로, 가용리더의 배치 형태는 원형 배치와 사각형 배치 그리고 탐색범위 확장을 위한 축소된 사각형 배치를 고려하였다. 또한, RTLS의 위치추정 실험 조건으로 LOS 전파환경을 가정하였으며, 수신된 sub-blink 수에 따른 가용리더의 배치 형태별로 위치추정 성능을 분석하였다. 본 논문에서 제안하는 위치추정 알고리즘을 적용하여 위치를 추정한 결과, 원형 리더 배치가 탐색범위 확장이 유리한 사각형 리더 배치에 비하여 우수한 위치추정 정확도를 보였다. 이에, 위치추정의 정확도가 우수한 원형배치와 확장이 유리한 사각형 배치의 장점을 절충하여 탐색범위 확장을 위한 축소 사각형 배치를 제안하였으며, 실험 결과, 제안한 위치추정 알고리즘이 탐색범위 확장을 고려한 축소된 사각형 리더 배치에서도 높은 위치추정 성능이 나타남을 확인하였다.

• 전자공학회논문지CI
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• 제43권5호
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• pp.38-47
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• 2006

기존의 인식 방법은 물체에 대한 형상 정보 또는 움직임을 특징으로 한 단일 인식기를 사용한다. 하지만, 기존의 단일 특징 기반의 단일 인식기를 사용하는 방법의 인식 성능은 물체의 영역에 대한 정확한 검출에 크게 의존하는 단점을 가진다. 본 논문에서는 이러한 기존 인식방법의 단점을 해결하고, 인식의 신뢰성을 높이기 위해서 세 가지 인식기에 의한 각 결과를 Bayesian을 이용하여 융합하는 새로운 인식 방법을 제안한다. 첫 번째 인식기는 푸리에 묘사자로부터 얻은 형상 정보를 특징으로 한 신경망을 사용하고, 두 번째 인식기는 형상 정보에 대한 기울기를 바탕으로 한 통계적인 방법을 사용한다. 또한. 세 번째 인식기는 검출된 물체의 일정 부분의 움직임에 대한 모션 정보를 특징으로 하여 인식한다. 본 논문의 실험결과에서 제안한 결과 융합방법은 기존의 Majority Voting과 Weight Average Score 방법에 비해서 더 우수한 인식 성능을 보여준다.

• 농업과학연구
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• 제47권4호
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• pp.753-767
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• 2020

The commercial value of strawberries is affected by various factors such as their shape, size and color. Among them, size determined by weight is one of the main factors determining the quality grade of strawberries. In this study, image technology was developed to predict the weight of strawberries using the shape characteristics of strawberry cultivars. For realtime weight measurements of strawberries in transport, an image measurement system was developed for weight prediction with a charge coupled device (CCD) color camera and a conveyor belt. A strawberry weight prediction algorithm was developed for three cultivars, Maehyang, Sulhyang, and Ssanta, using the number of pixels in the pulp portion that measured the strawberry weight. The discrimination accuracy (R2) of the weight prediction models of the Maeyang, Sulhyang and Santa cultivars was 0.9531, 0.951 and 0.9432, respectively. The discriminative accuracy (R2) and measurement error (RMSE) of the integrated weight prediction model of the three cultivars were 0.958 and 1.454 g, respectively. These results show that the 2D imaging technology considering the shape characteristics of strawberries has the potential to predict the weight of strawberries.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2003년도 춘계학술발표대회 논문개요집
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• pp.111-115
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• 2003

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.11-12
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• 2007

• 한국농공학회지
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• 제22권2호
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• pp.83-100
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• 1980

This study was intended to computerize the structural analysis of two-dimensional continuum by finite element method, and to provide a preparatory basis for more sophisticated and more generalized computer programs of this kind. A computer program, applicable to any shape of two-dimensional continuum, was formulated on the basis of 16-degree-of- freedom rectangular element. Various computational aspects pertaining to the implementation of finite element method were reviewed and settled in the course of programming. The validity of the program was checked through several case studies. To assess the accuracy and the convergence characteristics of the method, the results computed by the program were compared with solutions by other methods, namely the analytical Navier's method and the framework method. Through actual programming and analysis of the computed results, the following facts were recognized; 1) The stiffness matrix should necessarily be assembled in a condensed form in order to make it possible to discretize the continuum into practically adequate number of elements without using back-up storage. 2) For minimization of solution time, in-core solution of the equilibrium equation is essential. LDLT decomposition is recommended for stiffness matrices condensed by the compacted column storage scheme. 3) As for rectangular plates, the finite element method shows better performances both in the accuracy and in the rate of convergence than the framework method. As the number of elements increases, the error of the finite element method approaches around 1%. 4) Regardless of the structural shape, there is a uniform tendency in convergence characteristics dependent on the shape of element. Square elements show the best performance. 5) The accuracy of computation is independent of the interpolation function selected.

• 사상체질의학회지
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• 제20권1호
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• pp.42-47
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• 2008

1. Objectives The Body Shape and Feature is one of the important standard for classification of Sasang Constitutions. In order to evaluate one's Body Shape and Feature objectively we have been developing the Body Measuring Machine. Now we develop the 3D Automatic Body Measuring Machine(3D-ABMM). So we make an analysis of the 3D-ABMM's Accuracy. 2. Methods By using the 3D-ABMM and Vivid 9i(3D laser scanner, Konica Minolta) we have a surface scan of the three objects which are the upper body of the female and male Manikin and a male model. We overlap each scan data using the RapidForm2006 (3D scan data solution, INUS Technology) and calculate the average distance and standard deviation between the same point of each scan data. 3. Results and Conclusions In the female Manikin, the average distance is 0.84mm and the standard deviation is 1.16mm and the maximum distance is 10.68mm. In the male Manikin, the average distance is 1.12mm and the standard deviation is 1.19mm and the maximum distance is 12.00mm. In the male model, the average distance is 3.26mm and the standard deviation is 2.59mm and the maximum distance is 12.75mm. From the results, 3D-ABMM has good accuracy for scanning body and will be a usable hardware of the 3D Automatic Body Analysis Machine.