• 대한전자공학회논문지SD
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• 제44권4호
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• pp.103-109
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• 2007

본 논문은 최근에 많이 연구되고 있는 PLL 기반의 fractional-N 주파수 합성기에 관하여 SIMULINK 및 Verilog-a를 사용하여 모델링하는 방법론에 대하여 설명한다. 전통적으로 PLL 설계에 적용되는 바텀-업(bottom-up) 방식의 트랜지스터 레벨설계와 함께 탑-다운(top-down) 방식의 설계를 병행하여 적용함으로써 트랜지스터 레벨의 회로설계에 걸리는 시간을 크게 절약하고 SoC의 IP로서 아날로그 부분과 디지털부분이 같이 검증될 수 있는 방안을 고려하고자 한다. 이를 위하여 시스템의 동작여부를 빠르게 파악하고 top level에서의 검증이 용이한 SIMULINK 모델링과 트랜지스터 레벨과의 호환을 통해 블록 단위의 검증이 가능한 Verilog-a 모델링의 비교를 수행함으로서 효과적인 설계 방법을 제시한다.

• 대한기계학회논문집A
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• 제26권9호
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• pp.1772-1778
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• 2002

This paper describes inference architecture of an intelligent CAD system that is to be used for design tasks in which complex and large amount of knowledge is used. In order to investigate the issue of handling huge and complex knowledge, design knowledge is categorized into four types and inference methods for them are identified respectively: original design problems are decomposed into several modules of design processes and finally into sub-problems with the four types of knowledge as basic elements in a top-down manner. We demonstrate the implementation of the architecture with the result of the machining center - a sort of machine tools - design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.6-8
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• 2007

In this paper, We propose reasoning system for object recognition and space classification using not only visual features but also contextual information. It is necessary to perceive object and classify space in real environments for mobile robot. especially vision based. Several visual features such as texture, SIFT. color are used for object recognition. Because of sensor uncertainty and object occlusion. there are many difficulties in vision-based perception. To show the validities of our reasoning system. experimental results will be illustrated. where object and space are inferred by bi -directional rules even with partial and uncertain information. And the system is combined with top-down and bottom-up approach.

• 정보기술과데이타베이스저널
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• 제4권2호
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• pp.33-45
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• 1998

Database summarization is the procedure to obtain generalized and representative descriptions expressing the content of a large amount of database at a glance. We present a top-down summary refinement procedure to discover database summaries. The procedure exploits attribute concept hierarchies that represent ISA relationships among domain concepts. It begins with the most generalized summary and proceeds to find more specialized ones by stepwise refinements. This top-down paradigm reveals at least two important advantages compared to the previous bottom-up methods. Firstly, it provides a natural way of reflecting the user's own discovery preference interactively. Secondly, it does not produce too large intermediate result that makes it hard for the bottom-up approach to be applied in practical environment. The proposed procedure can also be easily extended for distributed databases. Information content measure of a database summary is derived in order to identify more informative summaries among the discovered results.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권3호
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• pp.319-329
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• 2016

High-level design aids are mandatory for design of a continuous-time delta-sigma modulator (CTDSM). This paper proposes a top-down methodology design to generate a noise transfer function (NTF) which is compensated for excess loop delay (ELD). This method is applicable to low pass loop-filter topologies. Non-ideal effects including ELD, integrator scaling issue, finite op-amp performance, clock jitter and DAC inaccuracies are explicitly represented in a behavioral simulation of a CTDSM. Mathematical modeling using MATLAB is supplemented with circuit-level simulation using Verilog-A blocks. Behavioral simulation and circuit-level simulation using Verilog-A blocks are used to validate our approach.

• 센서학회지
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• 제31권1호
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• pp.41-44
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• 2022

In this study, we have fabricated and characterized vertical double-gate (DG) InGaAs tunnel field-effect-transistors (TFETs) with Al₂O₃/HfO₂ = 1/5 nm bi-layer gate dielectric by employing a top-down approach. The device exhibited excellent characteristics including a minimum subthreshold swing of 60 mV/decade, a maximum transconductance of 141 µS/㎛, and an on/off current ratio of over 10³ at 20℃. Although the TFETs were fabricated using a dry etch-based top-down approach, the values of DIBL and hysteresis were as low as 40 mV/V and below 10 mV, respectively. By evaluating the effects of constant voltage and hot carrier injection stress on the vertical DG InGaAs TFET, we have identified the dominant charge trapping mechanism in TFETs.

• 전자공학회지
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• 제15권2호
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• pp.75-87
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• 1988

본 논문에서는 음성에 의한 man-machine communication의 핵심기술인 음성인식 및 합성의 전반적인 기술에 관하여 그 현황을 알아본다. 먼저 음성인식에서 해결되어야 할 문제점들을 고찰하고 격리단어 인식, 연결단어 인식, 그리고 연속언어 인식의 기술현황을 기술한다. 격리단어 인식에서는 pattern matching 방법에서 사용되는 입력어휘의 특징 추출, reference와의 유사도 측정, 유사도 측정 결과에 의한 인식결정에 관해서 논한다. 연결단어 및 연속언어 인식에서는 현재 연구가 되고 있는 "bottom-up approach"와 "top-down approach"에 관해서 설명하고 이들 방법의 어려운 점들을 고찰한다. 다음 음성 합성에서는 기존의 여러 가지 합성 방식을 검토하고 이들의 장단점을 기술한다. 마지막으로 한 예로서 한국어 text-to-speech 변환 시스템에 관하여 기술한다.

• 한국항행학회논문지
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• 제21권6호
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• pp.521-528
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• 2017

다수의 UAV가 다양한 임무를 수행하면서도 편대를 유지할 수 있도록 하는 집단적 지능을 갖춘 시스템을 구축하기 위해서는 AI에 관한 연구가 필수적이다. AI의 전형적인 접근 방법에는 전문가시스템을 비롯한 규칙기반의 논리 추론방식인 '하향식' 접근 방법과 인공신경회로망, Flocking Algorithm과 같이 단순 개체간의 부분적 상호작용을 통해 전체적인 행동이 결정되는 '상향식' 접근 방법이 있다. 기존의 Flocking Algorithm과 같은 연구에서는 개개인은 개별적인 임무를 수행 할 수 없다. 또한 UAV의 편대비행과 같은 연구에서는 편대의 부분적인 결함으로 발생하는 문제에 대해 유연하게 대처 할 수 없다. 본 논문에서는 다중에이전트 시스템을 통해 하향식 접근 방법과 상향식 접근 방법 간의 유기적 통합을 제시하고, 이를 통해, 유연한 임무수행이 가능한 편대 비행 알고리즘을 제시하였으며, 시뮬레이션을 통해 대형형성 및 충돌회피 등 유효성을 확인하였다.

• 한국체육학회지인문사회과학편
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• 제55권4호
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• pp.227-240
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• 2016

연구 부정행위는 체육학 연구에서 지속돼야 할 연구주제이지만 연구 부정행위의 복잡한 매커니즘과 연구 진실성을 확보하기 위한 방안에 관한 연구는 미진한 실정이다. 이에 본 연구는 체육학에서의 연구부정행위의 발생원인 및 해결방안을 학계 구성원의 관점에서 살펴보는데 목적을 두었다. 이를 위해서 근거이론 방법의 적용을 통해 13명의 학자 및 대학원생들에 집단인터뷰(focus group interview), 개인인터뷰(follow-up one-on-one interview), 서술적 설문조사(qualitative questionnaire)를 통하여 수집하였다. 연구결과 연구부정행위는 사회구조적(socio-political), 사회문화적(socio-cultural), 개인적(personal) 맥락에서 발생하는 것으로 인식되었으며, 해결 방안은 첫째, 위로부터의 변화(Top-down approach), 둘째, 아래로부터의 변화(Bottom-up approach), 셋째, 지속적인 교육 및 점검(Continuous education)의 변화가 제시되었다. 본 연구 결과를 통해 제시된 경험적 지식이 체육학을 연구하는 개인 연구자의 연구윤리 의식 제고에 활용되고, 대학의 교육 및 학계 차원의 향후 노력들에 기초자료로 사용되어지기를 기대한다.

• 한국연극학
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• 제40호
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• pp.307-344
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• 2010

Cultural Studies built on the critical mind of New Left exposes the relationship between culture and power, and investigates how this relationship develops the cultural convention. It has achieved the new perspective that could make us to think culture and art in terms of political correctness. However, the critical voices against the theoretical premises of Cultural Studies have been increased as its heyday in 1980s was nearly over. For instance, Terry Eagleton, a former Marxist literary critic, declared in 2003 that the golden age of cultural theory is long past. This essay, therefore, intends to show the weak foundations on which the approaches of cultural studies to theatre rest and to clarify the general problem of their introduction to theatre studies. The approach of cultural studies to theatre takes the form of 'top-down inquiry' as it applies a theory to a particular play or historical period. In other word, from the theory the writer moves to the particular case. The result is not an inquiry but rather a demonstration. This circularity can destroy the point of serious intellectual investigation as the theory dictates answers. The goal-oriented narrow viewpoint as a logical consequence of 'top-down inquiry' makes the researcher to favor the plays or the parts of a play that are proper to test a theory. As a result it loses the fair judgment on the artistic value of a play, and brings about the misinterpretation. The interpreter-oriented reading is the other defect of cultural studies as it disregards the inherent meaning of the text, distorting a play. The approach of cultural studies also consists of a conventionality as it arrives at a stereotyped interpretation by using certain conventions of reasoning and rhetoric. The cultural theories are fundamentally the 'outside theories' that seek to explain not theatre but the very broad features of society and politics. Consequently their application to theatre risks the destructive criticism, disregarding the inherent experience of theatre. Most of, if not all, cultural theories, furthermore, are proven to be lack of empirical basis. The alternative method to them is a 'cognitive science' that proves scientifically our mind being influenced by bodily experience. The application of cultural materialism to Shakespeare's is one of the cases that reveal the limits of cultural studies. Jonathan Dollimore and Water Cohen provide a kind of 'canonical study' in this application that is imitated by the succeeding researchers. As a result the interpretation of has been flooded with repetitive critical remarks, revealing the problem of 'top-down inquiry' and conventional reasoning. Cultural Studies is antipodal to theatre in some respect. It is interested chiefly in the social and political reality while theatre aims to create the fiction world. The theatre studies, therefore, may have to risk the danger of destroying its own base when it adopts cultural studies uncritically. The different stance between theatre and cultural theories also occurs from the opposition of humanism vs. antihumanism. We have to introduce cultural theories selectively and properly not to destroy the inherent experience and domain of theatre.