• International Journal of Fuzzy Logic and Intelligent Systems
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• 제10권1호
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• pp.65-72
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• 2010

For developing navigation system of total hip arthroplasty (THA) and evaluating hip joint kinematics, 3-D pose position of the femur and acetabulum in the pelvic coordinate system has been quantified. The pelvic coordinate system is determined by manually indicating pelvic landmarks in multidetector-row computed tomography (MDCT) images. It includes intra- and inter-observer variability, and may result in a variability of THA operation or diagnosis. To reduce the variability of pelvic coordinate system determination, this paper proposes an automated method in MDCT images. The proposed method determines pelvic coordinate system automatically by detecting pelvic landmarks on anterior pelvic plane (APP) from MDCT images. The method calibrates pelvic pose by using silhouette images to suppress the affect of pelvic pose change. As a result of comparing with manual determination, the proposed method determined the coordinate system with a mean displacement of $2.6\;{\pm}\;1.6$ mm and a mean angle error of $0.78\;{\pm}\;0.34$ deg on 5 THA subjects. For changes of pelvic pose position within 10 deg, standard deviation of displacement was 3.7 mm, and of pose was 1.28 deg. We confirmed the proposed method was robust for pelvic pose changes.

• 대한기계학회논문집A
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• 제21권6호
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• pp.981-987
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• 1997

Modern helicopter rotor blades with non-homogeneous cross section composed of anisotropic material rquire highly sophisticated structural analysis. Variation in cross section geometry makes this task of analysis more complicated. Since rotor blades generally are much longer than their lateral dimensions, one-dimensional models seem feasible, at least from a computational point of view. Therefore determination of the principal coordinate system is very important to remove the structural coupling for one-dimensional beam modelling. In this study, shear center, and principal direction. The method will be verified by comparing the results with confirmed experimental results.

• 디지털융복합연구
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• 제18권2호
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• pp.73-81
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• 2020

본 연구에서는 지적확정측량의 지구계측량에 따른 유형별 예정지적좌표도 작성 현황과 주변 도해 필지와의 불부합 문제를 분석하고, 향후 이를 최소화하기 위한 개선방안을 제시하고자 하였다. 현재 예정지적좌표도는 기준점 가감, 기준점 가감 및 현형법, 기준점 및 현형법 등 다양한 방법을 이용해 작성되고 있는 것으로 나타났다. 이로 인하여 지적 확정측량 지구계 예정지적좌표도와 주변 개별 필지들에서 중첩이나 공백 등의 불부합 문제가 발생하고 있는 것으로 나타났다. 또한 성과결정에 있어 불부합 문제 발생을 최소화하기 위한 구체적이고 세부적인 통일된 기준이 부족한 것으로 나타났다. 분석된 문제점에 대한 개선방안으로서 연구에서는 지구계 주변 필지들에 대한 수치좌표의 취득 및 관리, 예정지적좌표도 작성을 위한 성과결정 표준 매뉴얼의 작성 및 보급, 성과결정에 관한 교육프로그램 마련을 제시하였다.

• 한국공작기계학회논문집
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• 제17권4호
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• pp.133-139
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• 2008

With the increasing demand for higher production quality and growing competition in the global market, coordinate measuring machine(CMM) has been widely used in industry to improve the efficiency and effectiveness of measurement. In this paper the performance evaluation of coordinate measuring machine is proposed using design of experiments. A factorial design is applied to carry out the performance test proposed by ISO 10360 with a length bar and to investigate CMM measurement errors associated to orientation and length in the work volume. The determination of the significance of effects in an experiment is made through the analysis of variance(ANOVA). The results show that the proposed method is suitable to analyze the factors which affect the CMM measurement performance.

• 한국정밀공학회지
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• 제25권1호
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• pp.160-170
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• 2008

Shape morphing is the process of transforming a source shape, through intermediate shapes, into a target shape. Two main problems to be considered in three dimensional shape morphing are vertex correspondence and path interpolation. In this paper, an approach which uses the linear interpolation of the Laplacian coordinates of the source and target meshes is introduced for the determination of more plausible path when two topologically identical shapes are morphed. When two shapes to be morphed are different in shape and topology, a new method which combines shape deformation theory based on Laplacian coordinate and mean value coordinate with distance field theory is proposed for the efficient treatment of vertex correspondence and path interpolation problems. The validity and effectiveness of the suggested method was demonstrated by using it to morph large and complex polygon models including male and female whole body models.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.291-297
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• 2000

Modern helicopter rotor blades with non-homogeneous cross sections, composed of anisotropic material, require highly sophisticated structural analysis because of various cross sectional geometry and material properties. They may be subjected by the combined axial, bending, and torsional loading, and the dynamic and static behaviors of rotor blades are seriously influenced by the structural coupling under rotating condition. To simplify the analysis procedure using one dimensional beam model, it is necessary to determine the principal coordinate of the rotor blade. In this study, a method for the determination of the principal coordinate including elastic and shear centers is presented, based upon continuum mechanics. The scheme is verified by comparing the results with confirmed experimental results.

• 대한안전경영과학회지
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• 제14권1호
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• pp.217-224
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• 2012

Location-Based Services(LBS) is a service that provide location information by using communication network or satellite signal. In order to provide LBS precisely and efficiently, we studied how we can reduce the error on location determination of objects such people and things. We focus on using the least square method and triangulation positioning method to improves the accuracy of the existing location determination method. Above two methods is useful if the distance between the AP and the tags can be find. Though there are a variety of ways to find the distance between the AP and tags, least squares and triangulation positioning method are wildely used. In this thesis, positioning method is composed of preprocessing and calculation of location coordinate and detail of methodology in each stage is explained. The distance between tag and AP is adjusted in the preprocessing stage then we utilize least square method and triangulation positioning method to calculate tag coordinate. In order to confirm the performance of suggested method, we developed the test program for location determination with Labview2010. According to test result, triangulation positioning method showed up loss error than least square method by 38% and also error reduction was obtained through adjustment process and filtering process. It is necessary to study how to reduce error by using additional filtering method and sensor addition in the future and also how to improve the accuracy of location determination at the boundary location between indoor and outdoor and mobile tag.

• 품질경영학회지
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• 제22권3호
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• pp.85-98
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• 1994

In current coordinate measuring machine practice, there are no commonly accepted sample sizes for estimating form errors which have a statistical confidence. Practically, sample size planning is important for the geometrical tolerance inspection using a coordinate measuring machine. We determine and validate appropriate sample sizes for form error estimation. Also, we develop form error estimation methods with certain confidence levels based on the obtained sample sizes in various form errors: straightness, flatness, circularity, and cylindericity.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2004년도 한국우주과학회보 제13권2호
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• pp.296-299
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• 2004

KARI precision attitude determination system has been developed for high accurate geo-coding of KOMPSAT-2 image. Sensor data from two star trackers and a IRU are used as measurement and dynamic data. Sensor data from star tracker are composed of QUEST and unit vector filter. Filter algorithms consists of extended Kalman filter, unscented Kalman filter, and least square batch filter. The type of sensor data and filter algorithm can be chosen by user options. Estimated parameters are Euler angle from 12000 frame to optical bench frame, gyro drift rate bias, gyro scale factor, misalignment angle of star tracker coordinate frame with respect to optical bench frame, and misalignment angle of gyro coordinate frame with respect to optical bench frame. In particular, ground control point data can be applied for estimating misalignment angle of star tracker coordinate frame. Through the simulation, KPADS is able to satisfy the KOMPSAT-2 mission requirement in which geo-location accuracy of image is 80 m (CE90) without ground control point.

• 디지털융복합연구
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• 제13권9호
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• pp.259-267
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• 2015

본 논문에서는 직선을 판별하는 판별방법과 또한 직선으로 판정되는 경우 직선의 8가지 방향에 대한 판정을 위하여 좌표정보와 삼각함수 성질을 이용하여 직선 8반향 알고리즘을 제안하였다. 본 실험은 각 동작 별로 100회씩 총 800회를 실험 하였으며, 본 논문에서 제안한 알고리즘을 통한 정확도는 왼쪽 위로의 대각선 방향이 92%로 가장 높았으며 왼쪽 방향, 오른쪽 위로의 대각선 방향과 오른쪽 아래로의 대각선 방향이 모두 82%로 가장 낮은 인식률을 나타내었다. 이 방법은 기존 방법과는 다르게 학습과정 없이 이미지 처리를 통해 얻은 좌표 정보만으로 손 제스처 인식이 가능하다는 것을 보여준다.