1,720,960 research outputs found
Injection locking-based tunable repetition-rate multiplication of mode-locked lasers
No full textWe demonstrate all-fiber repetition-rate multiplication of mode-locked laser based on injection-locked slave laser. The fundamental repetition-rate of 78.4 MHz can be multiplied by a factor of 13 to 102 (1-GHz to 8-GHz)
3x3 MMI coupler 기반 집적형 광-마이크로파 위상 검출기
No full textThe present disclosure relates to an integrated phase detector. In an embodiment, a first multi-mode interference coupler that receives the optical signal and outputs optical signals with a plurality of modes, and a second multi-mode interference coupler that receives one of the optical signals with the plurality of modes and a modulated signal generated through performing a phase modulation on another of the optical signals with the plurality of modes by the microwave signal, and outputs a first optical interference signal and a second optical interference signal may be included
Microwave photonics applications of femtosecond laser based on optical-microwave phase detection and repetition rate multiplication
No full text학위논문(박사) - 한국과학기술원 : 기계공학과, 2020.2,[vii, 100 p. :]광주파수빗의 정립 이래 펨토초 레이저의 우수한 타이밍 안정도를 갖는 초단 광 펄스열은 광학 및 마이크로파 영역 전반에 활용되고 있다. 두 영역의 기술을 복합적으로 활용하는 마이크로파 광학은 기존의 전기적 측정 및 동기화 기술의 한계를 극복할 수 있는 해결책일 뿐만 아니라 다양한 광학 기법들의 실질적 적용 범위를 넓혀준다. 본 학위논문은 저잡음 광 펄스열의 마이크로파 광학 응용을 위한 기초연구로서 광-마이크로파 위상검출기의 구조 및 기능적 개선을 이루었으며 고반복률 형성을 위한 반복률 증배기법을 높은 신호 대 잡음비로 구현하였다. 나아가 저잡음 마이크로파 생성의 위상잡음 성능을 개선방안을 제시하고자 한다.한국과학기술원 :기계공학과
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
Residual phase noise characterization and optimization of fiber-loop optical-microwave
No full text학위논문(석사) - 한국과학기술원 : 기계공학과, 2016.2
,[iv, 49 p :]본 연구는 광섬유 루프 기반 광 마이크로파 위상검출기(FLOM-PD)의 잔류위상잡음 성능을 측정 및 분석한 결과이다. 대표적인 요인들로서 신호원인 레이저와 전기발진기, 상대세기잡음, 광신호의 세기 및 펄스폭,중심 파장, 역방향 위상변조 등이 미치는 영향에 대해 조사하였다. 레이저 신호원으로는 본 연구실에서 제작한 스트레치드펄스 영역 저잡음 78 MHz 어븀 광섬유 레이저와 한국표준과학연구원의 250 MHz menlo comb 을, 전기 신호원으로는 Hittite 사와 Inwave 사의 전압제어발진기를 사용하여 비교분석하였다. 최적화 결과 out-of-loop 측정을 통해 확인한 잔류위상잡음 층은 -156 dBc/Hz 수준까지 낮출 수 있었으며 최적 성능을 위해 요구되는 상대세기잡음과 입력신호 세기 범위 조건을 규명하였다.한국과학기술원 :기계공학과
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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