46,788 research outputs found
Yong-Jun Choi
No full text학위논문(석사)--아주대학교 공학대학원 :기계공학과,2015. 2기계가공 분야 중 절삭가공분야에서 머시닝센터를 활용한 가공은 CNC선반가공과 더불어 그 시장성이 크고 범용성이 뛰어난 대표적인 가공 공정이다. 절삭가공에서 알루미늄 합금은 가공성이 우수하고 기계적 성질이 뛰어나 차량 및 항공기관련 부품제작, 반도체 장비관련 부품제작, 통신장비관련 부품제작, 자동화 장비관련 부품제작 등 다양한 분야의 정밀 부품가공 소재로 활용되고 있다.
본 논문에서는 일선 산업현장에서 보편적으로 사용되고 있는 머시닝센터의 절삭조건을 기준하여 동일한 절삭조건하에 알루미늄 합금의 표면 거칠기의 영향을 실험하였으며 Al5052-O, Al6061-T6, Al7075-T6 재종의 표면 거칠기 영향에 대하여 다음과 같은 결론을 확인할 수 있었다. 알루미늄 합금의 세부 재종분류가 다르다고 할지라도 동일 절삭조건에서 절삭 실험을 진행하였을 때 표면 거칠기의 영향은 분류에 따라 일부의 영향을 나타내고는 있지만 그 차이가 미소하다 볼 수 있으며 표면 거칠기 특성은 Al5052-O 재종과 Al7075-T6이 유사한 특성을 나타내었다.
Al5052-O 재종은 알려진 바와 같이 연질의 특성으로 인하여 표면 거칠기 영향과는 별도로 동일 절삭조건의 실험에서 주축의 회전수와 이송속도가 상승하고 절삭폭이 큰 경우 가공 끝단 일부가 가공 중 발생된 전단력에 의해 변형되는 현상을 나타냄을 확인 할 수 있었으며 Al7075-T6 재종은 경질의 특성으로 인하여 동일 절삭조건에서 가공 끝단부에서 형상의 일부가 취성파괴 되는 현상을 나타남을 확인하였다. 산업현장에서 보편적으로 사용하던 알루미늄 합금의 세부 재종에 따른 절삭 조건 증감의 적용은 표면 거칠기 값의 측정실험 및 완성품의 치수 공차를 확인하였을 때 표면 거칠기 값의 변화 및 치수변화량에 큰 영향을 미치지 않는 것을 확인할 수 있었다.논문 요약
Abstract
표 목차
그림 목차
Ⅰ. 서 론 1
1. 연구의 배경 및 목적 1
Ⅱ. 이론적 배경 5
1. 절삭가공 5
1.1 밀링절삭 개요 5
1.2 NC System 및 머시닝센터 14
1.3 CAM 프로그램 및 절삭조건 개요 21
2. 표면 거칠기 25
2.1 표면 거칠기 정의 25
2.2 표면 거칠기 영향 및 측정의 필요성 26
2.3 표면 거칠기 종류 27
2.4 표면 거칠기 측정법 28
3. 알루미늄 합금의 특성 30
3.1 알루미늄 합금의 분류 30
3.2 알루미늄 합금의 화학적 조성 31
3.3 알루미늄 합금의 기계적 특성 31
Ⅲ. 실험장치 및 실험방법 32
1. 실험계획법 32
1.1 실험계획법 개요 32
1.2 실험계획법 기본원리 34
1.3 실험계획법 분류 35
1.4 실험계획법 선정 36
2. 실험시편 38
3. 실험장치 41
3.1 머시닝센터 41
3.2 절삭공구 42
3.3 바이스 42
3.4 CAM Program 43
3.5 표면 거칠기 측정기 43
Ⅳ. 실험결과 44
1. 실험결과 측정값 44
2. 실험결과 분석 50
2.1 Al5052-O Case 1 50
2.2 Al5052-O Case 2 52
2.3 Al5052-O Case 3 54
2.4 Al6061-T6 Case 1 56
2.5 Al6061-T6 Case 2 58
2.6 Al6061-T6 Case 3 60
2.7 Al7075-T6 Case 1 62
2.8 Al7075-T6 Case 2 64
2.9 Al7075-T6 Case 3 66
3. 전단변형 및 취성파괴 68
Ⅴ. 결론 69
참고 문헌 70
첨부 1. 표면 거칠기의 분류별 세부사항 73
첨부 2. 표면 거칠기 측정법 84
첨부 3. 가공용 알루미늄 합금의 분류 89
첨부 4. 가공용 알루미늄 합금의 화학적 조성 92
첨부 5. 가공용 알루미늄 합금의 기계적 특성 96
첨부 6. 절삭실험 도면자료 101
첨부 7. 절삭가공품 사진자료 102
첨부 8. Face milling 절삭 실험 107MasterManufacturing using machining center, as well as CNC lathe processing, is a representative manufacturing process with high marketability and applicability among machining area of machine work area. In machining, due to its superior machinability and mechanical property, aluminum alloy is applied to manufacturing of precision parts for various areas including automotive, aerospace, semiconductor, and etc.
In this study, effect of surface roughness of aluminum alloy is examined by applying the identical cutting conditions on industrial fields and following conclusions are obtained on the effect of Al5052-O, Al6061-T6 and Al7075-T6 material’s surface roughness. When cutting test are conducted with identical cutting condition, even detailed material alloys are different, the effect on surface roughness can be negligible and even similar characteristics are shown in material Al5052-O and Al7075-T6 material.
As known, due to its ductile property, Al5052-O material shows high spindle speed and feed rate in identical cutting condition and a part of its edge is deformed by shear force generation during the process when cutting width is large. Due to its brittle property, Al7075-T6 material shows brittle fracture at part of its edge with identical cutting condition. From the surface roughness measuring test and dimensional tolerance, it is confirmed that application of variation of cutting condition for detailed material types of aluminum alloy used in conventional industry sites does not affect significantly
Yong yu you hua zhi bei chao leng yuan zi hun he wu de guang xue ou ji jing
No full textChen, Jun = 用於優化製備超冷原子混合物的光學偶極阱 / 陳軍.Thesis M.Phil. Chinese University of Hong Kong 2014.Includes bibliographical references (leaves 109-117).Abstracts also in Chinese.Title from PDF title page (viewed on 29, November, 2016).Chen, Jun = Yong yu you hua zhi bei chao leng yuan zi hun he wu de guang xue ou ji jing / Chen Jun
Xi jun ji qun yun dong zhong shui dong xiang hu zuo yong de yan jiu
No full textZhai, He = 细菌集群运动中水动相互作用的研究 / 翟翯.Thesis M.Phil. Chinese University of Hong Kong 2015.Includes bibliographical references (leaves 54-59).Abstracts also in Chinese.Title from PDF title page (viewed on 08, November, 2016).Zhai, He = Xi jun ji qun yun dong zhong shui dong xiang hu zuo yong de yan jiu / Zhai He
Supplemental_Info_for_Design,_Fabrication,_Testing_by_Ko,_et_al._revised – Supplemental material for Thermotaxis and Chemotaxis Assays of Sperm
No full textSupplemental material, Supplemental_Info_for_Design,_Fabrication,_Testing_by_Ko,_et_al._revised for Thermotaxis and Chemotaxis Assays of Sperm by Yong-Jun Ko, Joon-Ho Maeng, Seung Yong Hwang and Yoomin Ahn in SLAS Technology</p
JUN Yong-Hoon, « Calendars and Calendrical Knowledge in Pre-modern Korea », 28 février 2017
No full textDans le cadre du séminaire de Sciences et savoirs de l’Asie orientale de la mondialisation de l'UMR CCJ, Catherine JAMI et Frédéric OBRINGER organisent une conférence intitulée « Calendars and Calendrical Knowledge in Pre-modern Korea » donnée par JUN Yong-Hoon (AKS) Mardi 28 février 2017 de 15h à 17h EHESS / Salle Elisabeth Allès 190 avenue de France 75013 Paris Calendars and Calendrical Knowledge in Pre-modern Korea This talk will start with a brief introduction to some annual calendars us..
Penggunaan Bahasa Cina dalam weblog di Malaysia / Teoh Jun Yong
No full textThe development of weblog in virtual world has progressed so rapidly that it has
influenced the different aspects of languages. The use of such language in our daily life
has caused various styles of language such as the internet Chinese language to evolve.
This research is carried out to identify and analyse the characteristics of the
internet Chinese language on weblog among the youth in our country. Besides,
researcher will also discuss the factors involved in the existence of the internet Chinese
language on weblog through the views of these youth.
As many as 40 weblogs have been collected as sample study. Only personal
weblogs are chosen in Chinese which have been presented on the internet from January
to December 2008 are used in this study. This sample study is analysed both
qualitatively and quantitatively. There are six aspects of linguistic like code mixing,
code switching, acronym, vulgar language, repeated and ghafalogical.
From the study, researcher had found that most of the local blogger prefer using
code mixing which include the use of Bahasa Melayu and English. In addition, it is
found that the use of emoticons, punctuation, ellipsis, fonts and colour are very common
among them. Feedback from respoundents shows that the blogger’s hidden identities a
main factor in creating new lexical items.
The study concludes that a neutral attitude should be adopted in view of the fact
that the number of such users are steadily increasin
Arithmetic of the moduli of semistable elliptic surfaces
No full text© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. We prove a new sharp asymptotic with the lower order term of zeroth order on ZFq(t)(B) for counting the semistable elliptic curves over F q (t) by the bounded height of discriminant Δ (X). The precise count is acquired by considering the moduli of nonsingular semistable elliptic fibrations over P 1 , also known as semistable elliptic surfaces, with 12n nodal singular fibers and a distinguished section. We establish a bijection of K-points between the moduli functor of semistable elliptic surfaces and the stack of morphisms L 1 , 12 n ≅ Hom n (P 1 , M¯ 1 , 1 ) where M¯ 1 , 1 is the Deligne–Mumford stack of stable elliptic curves and K is any field of characteristic ≠ 2 , 3. For char (K) = 0 , we show that the class of Hom n (P 1 , P(a, b)) in the Grothendieck ring of K–stacks, where P(a, b) is a 1-dimensional (a, b) weighted projective stack, is equal to L ( a + b ) n + 1 - L ( a + b ) n - 1 . Consequently, we find that the motive of the moduli L 1 , 12 n is L 10 n + 1 - L 10 n - 1 and the cardinality of the set of weighted F q -points to be # q (L 1 , 12 n ) = q 10 n + 1 - q 10 n - 1 . In the end, we formulate an analogous heuristic on Z Q (B) for counting the semistable elliptic curves over Q by the bounded height of discriminant Δ through the global fields analogy11Nsciescopu
Nanostructured titania-diphosphonate hybrid materials with a porous hierarchy
No full textAbstract not availableXue-Jun Zhang, Tian-Yi Ma, and Zhong-Yong Yua
대장 내시경 수련 시뮬레이터의 2 자유도 햅틱장치 개발
No full text학위논문(석사) - 한국과학기술원 : 기계공학전공, 2005.2, [ vi, 54 p. ]This thesis presents a new 2-DOF haptic device for a colonoscopy training simulator. The 2-DOF haptic device includes three parts, a translation motion part, a roll motion part, and folding guides. A wire-driven mechanism is used for translational force reflection. Roll torque is generated by a timing belt mechanism. These two mechanisms implement force and torque reflections large enough for the colonoscopy simulation. The folding guides keep the endoscope tube straight. The folding guides fold and spread like a curtain. This mechanism helps transmit forces and torques from the endoscope tip to the user.
The specifications of 2-DOF haptic device such as continuous and maximum exertable forces and torques; workspace; sensitivity; and inertia in each direction are evaluated. The force bandwidth of the device is also evaluated through frequency response tests. The force bandwidth is suitable for simulation of colonoscopy. The 2-DOF mechanism is decoupled, so that Jacobian matrix has only diagonal elements.
A closed-loop PD controller using a 6-DOF force/torque sensor is designed to reduce the friction and inertial effects. The user``s maneuvering forces are measured in real-time, and compensated for including the effects of coulomb and viscous friction. This provides the users with better transparent sensation of the simulation.
A questionnaire test is conducted to evaluate the 2-DOF haptic device. The result of the questionnaire is analyzed by using a statistical method.한국과학기술원 : 기계공학전공
Supplementary_Figure_S1_(1) – Supplemental material for LncRNA SNHG3 promotes cell growth by sponging miR-196a-5p and indicates the poor survival in osteosarcoma
No full textSupplemental material, Supplementary_Figure_S1_(1) for LncRNA SNHG3 promotes cell growth by sponging miR-196a-5p and indicates the poor survival in osteosarcoma by Jun Chen, Zhouyi Wu and Yong Zhang in International Journal of Immunopathology and Pharmacology</p
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