1,720,977 research outputs found
LEE, JAE HUN
No full text학위논문(석사)----아주대학교 산업대학원 :기계공학과,2008. 2표면실장기술(SMT:Surface Mount Technology)은 전자제품에 사용하는 부품을 인쇄회로기판(PCB) 표면에 장착(mounting)하여 접합하는 기술이다.이러한 기술을 구현하는 설비를 SMT 설비라 하며 이 설비 중에 Chip Mounter 라는 핵심설비가 존재한다. 본 논문에서는 Chip Mounter 설비에서도 Chip을 흡착, 이동하여 인쇄회로기판에 접합하는 HEAD의 개발과 적용에 관한 방법과 결과를 제시하고자 한다. HEAD를 설계 후 Modeling을 통하여 구조해석을 실행 하여 예상되는 문제의 해결방안을 도출하고, 가공 후 조립과정 및 TEST 시발생되는 문제를 효과적으로 해결 하는데 주안점을 두었다.본 논문의 HEAD의 개발을 통하여 다른 종류의 실장장비에도 적용성을 검토한다.1. 서론 = 1
1.1 연구배경 = 1
1.2 연구목적 = 2
2. 배경이론 = 4
2.1 칩마운터 = 4
2.1.1 개요 = 4
2.1.2 마운터의 기계구조 = 5
2.1.3 부품장착방식 = 7
2.1.4 헤드 수와 장착율 = 8
2.2 칩마운터의 시스템 구성 = 9
3. Head설계 및 구조해석 = 10
3.1 칩마운터 TechnicalTrends분석 = 10
3.2 Head시스템 설계 = 11
3.2.1 Z축 구성 = 12
3.2.2 Theta축 구성 = 13
3.2.3 R축 구성 = 14
3.2.4 Head의 Air구성 = 15
3.3 Head해석 = 16
3.3.1 HeadAssy:Case1 = 16
3.3.2 HeadAssy:Case2 = 22
3.3.3 HeadAssy:Case3 = 28
3.4 Head해석결과 = 34
4. Head조립 및 TEST = 36
4.1 Head조립 = 36
4.2 HeadTEST = 38
4.2.1 Z-AxisLoad분석 = 38
5.결론 = 40
참고문헌 = 42Maste
A comparing study of alloy 600 and alloy 690 on resistance to intergranular stress corrosion cracking(IGSCC)
No full text학위논문(석사) - 한국과학기술원 : 원자력공학과, 1993.2, [ [ii], 46 p. ]한국과학기술원 : 원자력공학과
Influence of random point defects introduced by proton irradiation on the flux creep rates and magnetic field dependence of the critical current density J c of co-evaporated GdBa2Cu3O7-δ coated conductors
Full text linkWe report the influence of random point defects introduced by 3 MeV proton irradiation (doses of 0.5 ×1016, 1 ×1016, 2 ×1016 and 6 ×1016 cm-2) on the vortex dynamics of co-evaporated 1.3 μm thick, GdBa2Cu3O7-δ coated conductors. Our results indicate that the inclusion of additional random point defects reduces the low field and enhances the in-field critical current densities J c. The main in-field J c enhancement takes place below 40 K, which is in agreement with the expectations for pinning by random point defects. In addition, our data show a slight though clear increase in flux creep rates as a function of irradiation fluence. Maley analysis indicates that this increment can be associated with a reduction in the exponent μ characterizing the glassy behavior.Fil: Haberkorn, Nestor Fabian. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Kim, Jeehoon. No especifíca;Fil: Suarez, Sergio Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Lee, Jae Hun. No especifíca;Fil: Moon, S. H.. No especifíca
In-field dependences of the critical current density Jc in GdBa2Cu3O7-d coated conductors produced by Zr irradiation and post-annealing at low temperatures
No full textWe report the influence of 6 MeV Zr4+irradiation and post-irradiation annealing (200 °C) in the in-field dependences of the critical current densities Jc of 1.3 thick GdBa2Cu3O7-d coated conductors grown by co-evaporation. Samples were irradiated with 6 MeV Zr4+ and fluences between 2.3 × 1011 cm−2 and 3 × 1012 cm−2. The correlation between the superconducting critical temperature Tc and in-field dependences of Jc has been analyzed. In addition, random disorder introduced by irradiation was reduced by thermal annealed at 200 °C. The analysis of our experimental findings indicates that the optimal irradiation (reducing random disorder by annealing) results in the suppression of the self-field Jc of ≈10% and in-field Jc enhancements nearly doubled at about 5 T. A clear correlation between Tc, disorder and self-field Jc is observed. Additional random disorder and nanoclusters suppress systematically Tc and increase the flux creep relaxation at intermediate temperatures (reducing the characteristic glassy μ value).Fil: Haberkorn, Nestor Fabian. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Suarez, Sergio Gabriel. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Lee, Jae Hun. No especifíca;Fil: Moon, S.H.. No especifíca;Fil: Lee, Hunju. No especifíca
Competition between pinning produced by extrinsic random point disorder and superconducting thermal fluctuations in oxygen-deficient GdBa2Cu3Ox coated conductors
Full text linkWe report on the influence of random point defects introduced by 3 MeV proton irradiation on the vortex dynamics of 1.3 μm thick GdBa2Cu3Ox coated conductors. Thin films with different oxygen stoichiometry (6.7 < × < 7) were irradiated with 3 MeV proton (p) using a fluence of 2 × 1016 p cm−2. We find a direct correlation between the changes in Tc produced by oxygen content and damage by irradiation on the resulting vortex dynamics in the films. The analysis of the critical current densities Jc at low temperatures indicates that although irradiation produces smooth magnetic field dependences, the self-field values decrease systematically as Tc reduces. Moreover, the analysis of the relaxation of the persistent currents shows that the characteristic glassy exponent μ systematically decreases from 1.7 to 0.66 as Tc decreases from 93 to 55 K.Fil: Haberkorn, Nestor Fabian. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Guimpel, Julio Juan. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Suárez, S.. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Lee, Jae-Hun. No especifíca;Fil: Lee, Hunju. No especifíca;Fil: Moon, S.H.. No especifíca
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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