• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.179-180
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• 2006

In this study, the effect of stem-end design on contact pressure and stress distribution in revision TKR was investigated using finite element method. The finite element model of tibia, including the cortical bone, the cancellous bone and canal, was developed based on CT images. The stem models with various stem lengths, diameters and frictional coefficients, and press-fit effects were considered. The results showed that the longer stem length, the stronger press-fit, the bigger stem diameter, and the higher frictional coefficient increased both peak contact pressure and the highest Von-Mises stress values. We hypothesized that peak contact pressure and Von-Mises stress distribution around the stem, may be related to the stem end pain. The results of this study will be useful to design the stem endand reduce the end-of-stem pain in revision TKR.

• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.88-95
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• 2014

Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1991년도 춘계학술대회 논문집
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• pp.321-327
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• 1991

High power laser beams are used in a wide variety of materials processing applications such as cutting, welding, drilling and surface treatment. The CO$\sub$2/ laser is increasingly used in laser beam welding because of the highly potential advantages. High power laser welding is a high energy density, no filler metals and low heat input process to join metals. As the comparison with the conventiona welding, precision work and good fit-up to join the metals are required and maintenance is expensive at present. The principal variables of laser beam welding are the laser beam power, travel speed and bean spot size. The penetration depth during laser beam welding is directly related to the power density of the laser beam. Generally, for a constant beam size, the penetration depth increases with increasing laser beam power.

• 구강회복응용과학지
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• 제24권2호
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• pp.193-201
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• 2008

하악 완전 무치악 환자의 보철수복에 있어 임플란트 식립 후 피개의치의 제작은 첫 번째 치료 옵션으로 고려되어질 수 있다. 임플란트 지지 텔레스코프 피개의치를 제작하는 경우 인공치 및 유지 장치의 배열을 위한 악간 공간이 필요하다. 임플란트 상부 보철물의 passive한 fit은 보철물의 기계적 실패를 막는 중요한 요소이다. Gold electroforming system을 이용하여 제작한 telescopic attachment는 우수한 마진 적합도 및 passive한 fit을 보이며 얇은 코핑 두께로 인하여 좁은 악간 공간에서도 사용이 가능한 장점이 있다. 본 증례에서는 4개의 임플란트 식립 후 Gold electroforming system을 이용하여 telescopic overdenture를 제작하여 기능 및 심미적으로 좋은 결과를 나타내었다.

• Computers and Concrete
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• 제26권5호
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• pp.421-427
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• 2020

In this study, the two-dimensional generalized finite integral transform(FIT) approach was extended for new accurate thermal buckling analysis of fully clamped orthotropic thin plates. Clamped-clamped beam functions, which can automatically satisfy boundary conditions of the plate and orthogonality as an integral kernel to construct generalized integral transform pairs, are adopted. Through performing the transformation, the governing thermal buckling equation can be directly changed into solving linear algebraic equations, which reduces the complexity of the encountered mathematical problems and provides a more efficient solution. The obtained analytical thermal buckling solutions, including critical temperatures and mode shapes, match well with the finite element method (FEM) results, which verifies the precision and validity of the employed approach.

• Communications for Statistical Applications and Methods
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• 제14권1호
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• pp.71-80
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• 2007

The present paper investigates estimation of a scale parameter of a gamma distribution using a loss function that reflects both goodness of fit and precision of estimation. The Bayes and empirical Bayes estimators rotative to balanced loss functions (BLFs) are derived and optimality of some estimators are studied.

• Journal of the Korean Statistical Society
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• 제32권3호
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• pp.289-298
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• 2003

We consider the estimation problem for the scale parameter of the Rayleigh distribution using weighted balanced loss function (WBLF) which reflects both goodness of fit and precision. Under WBLF, we obtain the optimal estimator which creates a kind of balance between Bayesian and non-Bayesian estimation. We also deal with the estimation of R ＝ P(Y < X) when Y and X are two independent but not identically distributed Rayleigh distribution under squared error loss function.

• 한국정밀공학회지
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• 제18권6호
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• pp.74-79
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• 2001

In this study, a failure mode analysis of CNC machining center is described. First, the system is classified through subsystems into components using part lists and drawings. The component failure rate and failure mode analysis are performed to identify the weak components of a machining center with reliability database. The failure probabilistic function of mechanical part is analyzed by Weibull distribution. The Kolmogorov-Smirnov test is also used to verify the goodness of fit.

• 한국정밀공학회지
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• 제17권4호
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• pp.114-120
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• 2000

Burr is an unavoidable and undesirable by-product of most metal cutting or shearing operations. This burr must be removed to improve the fit of machined parts and safety of workers, to improve the effectiveness of finishing operations. Despite the full or partial automation of FMC or FMS, deburring operations to obtain workpiece with fine surface quality are difficult to be automated since the occurrence and condition of burr are not constant. This study focused on developing a software for deburring automation, which includes automatic recognition of parts, generation of deburring tool path and NC code, by analyzing the IGES format file which contains information of part geometry. The successful performance of developed software was demonstrated by computer simulation and deburring experiment using miniature end brush. And, this research can provide a basis for further advanced studies for automated deburring applications.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.466-469
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• 2002

Burr is a projected part of finished workpiece. It is unavoidable and undesirable by-product of most metal cutting or shearing process. Also, it must be removed to improve the fit of machined parts, safety of workers, and the effectiveness of finishing operation. But deburring process is one of manufacturing processes that have net been successfully automated, so deburring automation is strongly needed. This paper focused on developing a basic algorithm to find edge of workpiece and match two different image data for deburring automation which includes automatic recognition of parts, generation of deburring tool paths and edge/corner finding ability by analyzing the DXF drawing file which contains information of part geometry. As an algorithm for corner finding, SUSAN method was chosen. It makes good performance in finding edge and corner in suitable time. And this paper suggested a simple algorithm to find matching point between CCD image and drawing file.