• Biomaterials and Biomechanics in Bioengineering
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• 제3권2호
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• pp.85-104
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• 2016

Stability and loosening of implanted femoral stems in Total Hip Replacement have been well established as barriers to the primary concerns of osseointegration and long term implant survival. In-vitro experiments and finite element modeling have for years been used as a primary tool to assess the bone stem interface with variable methodologies leading to a wide range of micromotion, interference fit and stress shielding values in the literature. The current study aims to provide a comprehensive review of currently utilized methodologies for in-vitro mechanical testing as well as finite element modeling of both micromotion and interference of implanted femoral stems. A total of 12 studies detailed in 33 articles were selected for inclusion. Experimental values of micromotion ranged from 12 to $182{\mu}m$ while finite element analysis reported a wider range from 2.74 to $1,277{\mu}m$. Only two studies were found that modeled bone/implant contact with consideration for interference fit. In studies evaluating stem micromotion in THA, the reference surface at the bone/stem interface should be well defined. Additionally, the amount of penetration considered should be disclosed and associated with bone density and roughness.

• 한국정밀공학회지
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• 제22권5호
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• pp.80-86
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• 2005

Optical performance evaluation results and an interference fringe pattern analysis of alignment errors for an optical head of a near-field receding (NFR) system are presented. The focusing unit is an optical head of a NFR system and is composed of a solid immersion lens (SIL) and an objective lens (OL). Generally, the size of the focusing unit is smaller than that of the conventional optical recording head. Hence there are difficulties to assemble the small focusing unit precisely. We composed an evaluation system with an interferometer and evaluated some focusing unit samples aligned and assembled by manual and present the obtained results. Using the conventional optical tool, Code V, a tolerance analysis of the alignment error between the SIL and the objective lens and an interference pattern analysis for the assembly error are executed. Then, through an analysis of the simulation results, the conceptual auto-alignment methodology using a neural network approach is considered.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1992년도 춘계공동학술대회 발표논문 및 초록집; 울산대학교, 울산; 01월 02일 May 1992
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• pp.299-308
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• 1992

Determining tool-approach directions is an important issue when an effort is made to transfer CAD data into manufacturing automatically. An algorithm is developed to determine whether a given part can be machined on a three-axis milling machine. lf a set of feasible tool-approach directions exists for a sculptured surface, the NC tool path and G-codes for machining the surface on a three-axis milling machine can be generated automatically by an NC tool path generation algorithm. The algorithm can be used for orientation and fixturing of the workpiece for interference free machining. The algorithm can also be applied to checking the translational separability of polyhedral parts in automatic assembly.

• 한국기계가공학회지
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• 제8권4호
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• pp.41-47
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• 2009

This research deals with evaluation of machining accuracy for Parallel Kinematic Machine Tool(PKMT) applied parallel type robot system with high precision and stiffness. For this purpose, machine simulation is carried out to foreknow collision and interference between workpiece and tool. Furthermore, on the basis of machine simulation data, PKMT is manufactured. Machining accuracy such as cylindricity straightness, squareness, parallelism circularity, concentricity pitch error and yaw error, is measured by using coordinate measuring machine. Test piece for evaluation of machining accuracy is designed and manufactured under the standard of ISO 10791-7.

• 대한조선학회논문집
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• 제44권2호
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• pp.198-209
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• 2007

In this paper, we present the gouging and collision-free tool-path generation for manufacturing model propellers using the 5-axis NC machine. Because it takes much time to generate tool-paths when we use general purpose CAD/CAM systems, a specific system would be necessary for marine propellers. Overall manufacturing process is composed of two steps: roughcut and finishcut steps. The roughcut is conducted using only 3-axis for efficient machining and the finishcut is done using 5-axis for avoiding collision. The tool-path that might happen to gouging is searched and the tool position is also decided for avoiding interference between the tool and the propeller blades. The present algorithm is applied extensively to the surface piercing propellers. Some results are demonstrated for its validation.

• 한국항공우주학회지
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• 제41권3호
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• pp.246-252
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• 2013

본 논문에서는 항공기에 장착되는 RF(Radio Frequency) 장비간의 신호 간섭을 방지하기 위한 방안으로 가해 장비의 RF 단에 필터를 사용하여 간섭 성분을 억제하는 방안을 제안한다. 특히 가해 장비에서 발생하는 고조파 성분의 억제를 위한 필터 설계와 필터 성능을 검증하기 위한 시험 방안을 제시한다. 필터는 U/VHF(Ultra/Very High Filter) 무전기와 데이터링크 시스템간의 간섭을 방지하기 위해 U/VHF 무전기의 RF 단에 설치하였다. 본 논문에서의 필터 설계와 시험 방안은 항공기에서 발생하는 간섭 문제에 대한 대책을 수립할 수 있는 도구로써 항공기 RF 장비 설계에 도움을 줄 것이다.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.11-18
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• 1999

Recently high speed machining is being studied actively to reduce machining time and to improve machining precision. To perform efficient high speed machining, evaluation of high speed machinability must be studied preferentially and it can be identified by investigation of cutting force. To measure cutting forces in high speed machining, dynamometer which has high natural frequency was newly designed using 3-axes piezo force sensor. For newly designed dynamometer, calibration is conducted with sensitivity of force sensor modulated and proper preload and interference force are investigated experimently. Also, cutting force signals of newly designed dynamometer are compared with those of conventional one in high speed cutting experiment and its superiority is confirmed. Then using newly designed dynamometer, high speed machinability is evaluated about cutting force and tool wear in various cutting conditions.

• 한국기계가공학회지
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• 제10권2호
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• pp.1-8
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• 2011

5-axis NC machining has a good advantage of the accessibility of tool motion by adding two rotary axes. It offers numerous advantages such as expanding machining fields in parts of turbo machineries like impeller, propeller, turbine blade and rotor, reasonable tool employment and great reduction of the set-up process. However, as adding two rotary axes, it is difficult to choose suitable machining conditions in terms of cutter path and cutter posture at a cutter contact point. Therefore in this paper, it is proposed to decide suitable machining condition through an experimental method such as adopting various cutter paths, cutter postures types. Also, in order to increase the efficiency of 5-axis machining, it is necessary to minimize the cutter posture changes and create a continuous cutter path while avoiding interference. This study, by using an MC-space algorithm for interference avoidance and an MB-spline algorithm for continuous control, is intended to create a 5-axis machining cutter path with excellent surface quality and economic feasibility. finally, this study will verify the effectiveness of the suggested method through verification processing.

• 한국인터넷방송통신학회논문지
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• 제11권4호
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• pp.251-256
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• 2011

본 논문은 채널 공유를 위한 기준 간섭확률 대비 두 시스템인 WiBro 와 WLAN간의 이격거리를 분석하여 상용화의 기준 자료가 되도록 하였다. Monte-Carlo 방법에 기초한 Spectrum Engineering Advanced Monte Carlo Analysis Tool(SEAMCAT)을 이용하여 TV White Spaces(TVWS) 대역의 동일 및 인접채널에서 WiBro가 무선랜에 미치는 간섭확률 및 그 영향을 분석하였다. 분석 결과, 동일채널에서 WiBro Mobile Station(MS)의 최대 송신파워(25 dBm)를 허용하기 위해 WiBro MS와 무선랜 User Equipment(UE) 사이에 210 m의 이격거리가 요구된다. 또한, WiBro Base Station(BS)의 송신파워는 -4.96 dBm으로 감소되어야 한다.

• Genomics & Informatics
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• 제11권1호
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• pp.55-57
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• 2013

Growing numbers of studies employ cell line-based systematic short interfering RNA (siRNA) screens to study gene functions and to identify drug targets. As multiple sources of variations that are unique to siRNA screens exist, there is a growing demand for a computational tool that generates normalized values and standardized scores. However, only a few tools have been available so far with limited usability. Here, we present siMacro, a fast and easy-to-use Microsoft Office Excel-based tool with a graphic user interface, designed to process single-condition or two-condition synthetic screen datasets. siMacro normalizes position and batch effects, censors outlier samples, and calculates Z-scores and robust Z-scores, with a spreadsheet output of >120,000 samples in under 1 minute.