FDM 방식에서의 효율적인 서포트 제거를 위한 최적 설계ㅒ

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2017. 2. 이건우.We propose an optimization framework for a support removal process. Support removal is an issue among increasing users of fused deposition modeling (FDM). Many users have to use tools to eliminate support structures from 3D-objects. Furthermore, while removing support, the 3D-object tends to break when too much stress is applied. Prior to building a 3D-object, our algorithm provides the optimal orientation that minimizes the amount of support structures using a convex-hull algorithm. Also by providing a deformable support structure that detaches better when the same force is applied, we aim to facilitate the support removal process for FDM users. We have compared our support structure generation algorithm with support structures from existing software using a materials tester, INSTRON 5900R. We also compared the time required to remove the support structure.Chapter 1. Introduction 1 Chapter 2. Related work 5 2.1. Support structure 5 2.2. Infill structure 6 2.3. Orientation analysis 6 Chapter 3. Support structure 8 3.1. Support region 8 3.2. Deformable support structure generation 12 3.2.1. Line support generation 13 3.2.2. Connecting the lines 15 3.2.3. Splitting the deformable support structure 22 3.3. Characteristics of deformable support structure 24 Chapter 4. Part orientation for minial support 27 4.1. Overhang 27 4.2. Support amount estimation 28 4.3. Convex-hull algorithm 30 Chapter 5. Result 31 Chapter 6. Result 36 Bibliography 37 Abstract in Korean 39Maste

A Study on the Making of Canoe Model by Laminated Wooden Plates Using 3D CAD Systems

The canoe is typical one of oar boat has the artistic advantage than generic mold based plastic ship. For hobbyist or others the canoe is built by the strips of wood. However, much of times, man powers and making resources to building of ship body and smooth surfaces are required. And it is very difficult to design for mass producing on business. On this paper, the new approaches to making of canoe are studied for piling the laminated wooden plates. It is designed by 3D CAD/CAM/CAE system required for modeling. The Whole shape of ship is reproduced the sliced plates for laminated one. The drawings from the system are used to making the laminated wooden plates for ship body. Compare with the strip based, most of wooden materials are available for this method. After the stepped ship body is piled, the grinding and sanding are required for smooth surfaces. For more productive in business purpose, the manufacturing by the machines are used for it.제1장 서론 1.1 연구 배경 ……………………………………………………… 1 1.2 연구 목적 ……………………………………………………… 2 제2장 카누 제작 방식의 분석 2.1 카누의 설계 구조와 제작 조건 ……………………………… 4 2.1.1 카누의 구성 요소 …………………………………………… 4 2.1.2 카누의 선형 요소 …………………………………………… 6 2.1.3 카누의 재료 ………………………………………………… 10 2.2 카누 제작 방식 분석 ………………………………………… 12 2.2.1 졸대 전개식 공정 분석 …………………………………… 12 제3장 적층식 키트형 카누의 설계와 제작 3.1 적층식 카누 설계 공정 ……………………………………… 19 3.1.1 3차원 카누 형상 설계 …………………………………… 20 3.1.2 적층식 키트 형상 정보 생성 ……………………………… 24 3.1.3 형상 해석 …………………………………………………… 33 3.1.4 키트 제작을 위한 가공 정보 생성 ……………………… 37 3.2 적층식 키트형 카누 제작 …………………………………… 40 3.3 카누 제작 공정 비교 ………………………………………… 49 제4장 결론 ……………………………………………………… 51 참고 문헌 ………………………………………………………… 5

터보차져가 장착된 디젤엔진에서 과도 운전 시 과급압 및 분사시기가 연료 소비율에 미치는 영향

학위논문(석사)--아주대학교 일반대학원 :기계공학과,2008. 8최근 고유가와 높은 배기 가스 규제는 완성차 업체들로 하여금 연비 개선에 많은 비용과 노력을 기울이도록 하고 있다. 디젤 엔진은 가솔린 대비 높은 열효율로 좋은 연비를 갖지만 배기 가스와 소음 문제로 각광받지 못하였다. 그러나 최근 후처리 기술의 발달과 함께 연비 및 동력 성능을 개선하는 기술이 많이 발달되어 많은 관심을 받고 있다. 디젤 엔진의 더 높은 연비와 열효율을 위해 현재 다양한 동력계 실험이 진행되고 있으며 선행 연구원들에 의해 그 방법은 많이 적립되었다. 차량 동력계를 이용해 차량의 에너지 흐름과 연료 소비율을 측정하는 실험을 통해 디젤 차량이 과도 상태에서 정속 상태에 비해 낮은 과급 압력과 늦은 연료 분사 시기를 갖는 것으로 나타났다. 이로 인해 연료 소비율 또한 정속 상태와 비교하여 높은 값을 나타내었다. 과도 구간 중 가속 구간은 FTP-75모드와 NEDC모드에서 각각 전체 연료 소비량의 약 50%와 30%를 차지할 정도로 전체 연비에 매우 큰 영향을 끼치는 인자이다. 따라서 본 연구에서는 엔진 동력계를 통해 차량의 과도 구간에 서 엔진 특성을 구현한 뒤 과도 구간의 엔진 회전수와 연료량이 같은 정속 실험을 통해 과도 구간의 연료 분사 시기와 과급압 그리고 연료 소비율의 차이를 분석하였다. 그리고 정속 시험 결과를 기준으로 연료 분사 시기를 진각 또는 지각하여 각각이 연료 소비율에 미치는 영향을 분석하였고, 부하가 다를 때 연료 분사 시기가 연료 소비율에 미치는 영향을 분석하였다. 또한 과급압의 변화할 때 연료 소비율의 변화를 측정하였고, 이를 통해 과도 구간과 정속 구간에서 연료 소비율이 차이나는 주요 원인은 과도 구간의 낮은 과급압 때문임을 밝혀냈다..제1장 서론 = 1 1.1 연구 배경 및 목적 = 1 1.2 연구 내용 = 4 제2장 엔진 동력계 실험 = 5 2.1 실험 장치 및 실험 방법 = 5 2.1.1 실험 장치 = 5 2.1.2 실험 방법 = 7 2.2 실험 결과 및 분석 = 9 2.2.1 과도 및 정속 실험 결과 = 9 2.2.2 연료 분사 시기에 따른 연료 소비율 측정 결과 = 15 2.2.2.1 엔진 회전수에 따른 실험 결과 = 15 2.2.2.2 부하에 따른 실험 결과 = 27 2.2.2.3 연료 분사 시기 차이에 의한 과도 상태와 정속 상태의 연료 소비율 차이 분석 = 43 2.2.3 과급압에 따른 연료 소비율 측정 결과 = 45 2.2.4 연료 분사 시기 지각 및 과급압에 의한 과도 상태와 정속 상태의 연료 소비율 차이 분석 = 59 제3장 결론 = 61 제4장 참고 문헌 = 64 ABSTRACT = 66MasterFuel consumption and Engine efficiency are come up for the most important factor of Vehicle. Because of sudden increase of fossil fuel price and interest of fuel consumption, so, many research and development is executed in the automobile companies. To improve fuel economy, the most important mission in diesel engine is reduction of specific fuel consumption via a injection timing and boost pressure. In a commercial vehicle, injection timing was retarded from the steady-state injection timing on transient condition. Also Boost pressure is lower than steadystate condition. These factors cause increment of specific fuel consumption on transient condition. In FTP-75 mode test or NEDC mode test, vehicle use 30~50% fuel in transient condition. So reduction of specific fuel consumption in transient condition is most important factor to enhance vehicle fuel economy. In this paper, transient condition and steady-state condition is executed by engine dynamometer. And injection timing and boost pressure is compared between transient condition and steady-state condition. On transient condition, injection timing is retarded and boost pressure lower than steady-state condition. Thus, specific fuel consumption is upper than steady-state condition. By injection timing and boost pressure variation experiment, it is cleared that Boost Pressure is more significant factor for specific fuel consumption on transient condition of turbo charger diesel engin

Calibration of phase-shifting projection moire 3-D surface measuring system

학위논문(석사) - 한국과학기술원 : 기계공학과, 1998.2, [ ix, 97 p. ]한국과학기술원 : 기계공학과

Two-Wavelength Phase-Shifting Projection Moire Topography for Measurement of Three-Dimensional Profiles with High Step Discontinuities

[$Moir\acute{e}$] technique is now being extensively investigated as a fast non-contact means of three-dimensional profile measurement especially for reverse engineering. One problem with $moir\acute{e}$ technique is so called $2\pi$-ambiguity problem that limits the maximum step height difference between two neighboring sampling points to be less than half the equivalent wavelength of $moir\acute{e}$ fringes. In this investigation, a new two-wavelength scheme of projection $moir\acute{e}$ topography is proposed and tested to cope with the $2\pi$-ambiguity problem. Experimental results are discussed to assess the new method in measuring large objects with high step discontinuities

저가간섭광을 이용한 산란 매질의 편광 토모그래피

학위논문(박사) - 한국과학기술원 : 기계공학전공, 2003.8, [ vi, 114 p. ]PS-OCT(Polarization-Sensitive Optical Coherence Tomography) is adapted to aquire microscopic tomography of light polarization change inside scattering media. PS-OCT can extract depth-resolved polarization change by combining photon selection ability based on low coherence of source and interferometric ellipsometry. In order to improve PS-OCT technology, firstly, statistics of PS-OCT signals is identified. The amplitude of the detected signal is found to faithfully follow the Rayleigh distribution predicted by the scattering theory of electromagnetic waves in random media. The probability density function of the phase difference between the two orthogonal signal components of PS-OCT is explicitly derived and then verified in comparison with the experimental data measured from in-vitro tissues. Secondly, to describe PS-OCT signals for various scattering media, a Monte Carlo model for polarized light propagation in a multiple layered birefringent scattering medium based on the Jones formalism and Mie scattering theroy is developed. The simulation makes it possible to derive the depth-resolved Stokes vector, which provides a complete characterization of the optical polarization state change of a scattering media. The experimental PS-OCT system is utilized to expand PS-OCT applications for engineering materials and tissues. Nondestructive testing of translucent glass-epoxy composites was performed to map the inside stresses distribution by means of the PS-OCT. Cross-section image of Stokes vectors successfully visualize internal stress distribution and microscopic damage inside composite. The developed system is also exploited to classify types of connective tissue. Sample tissues corresponding to typical connective tissue types were extracted from human tongue, bovine cartilage and rodent skin, and PS-OCT images for each tissue are compared with morphological characteristics of tissues including collagen fiber types and its orientation.한국과학기술원 : 기계공학전공