• Journal of Mechanical Science and Technology
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• 제20권12호
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• pp.2087-2093
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• 2006

In this paper, auto focus actuator, which is used to move a lens module in the mobile phone having a camera module, is developed. Camera module containing auto focus actuator requires to minimize total size because of characteristics of the application area such as mobile phone, digital camera, and personal digital assistant. There are stepping motor, voice coil motor, and piezoelectric motor as auto focus actuator. In this paper, voice coil motor having new electromagnetic configuration is proposed. And actuator using proposed voice coil motor is developed by optimal design method using magnetic circuit analysis. The sectional area of the developed actuator is reduced to 32.4% compared with actuator using general electromagnetic configuration. From the performance test, the developed actuator has moving stroke of 0.64 mm for 2.1 volt, hysteresis of 40 $\mu$m, full stroke current of 54 mA, and unit step motion of 3 $\mu$m.

• 한국정밀공학회지
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• 제22권9호
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• pp.115-122
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• 2005

Errors resulting from magnification variations of a optical system are largely generated in three-dimensional shape measurements based on depth-from-focus. In the case of measuring the surface morphology of tiny objects based on DFF, images are acquired with a very small interval so that magnification changes can be minimized. However, the magnification variations are actually existed in the acquired images and so focus measures are wrongly or ambiguously extracted. In this paper, a methodology with linear magnification calibrations, based on DFF, is proposed to make more accurate measurement in surface morphology with high depth discontinuity, compared with previous ones. Several experiments show that the proposed method outperforms existing ones without magnification calibrations.

• 소음진동
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• 제11권1호
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• pp.49-56
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• 2001

In this paper, two plant models, of which one is newly developed and the other one is the conventional one, of the focus servo system of DVD drive are presented and a two-degree-of freedom controller consisted of Inverse dynamics feedforward and LQG/LTR feedback controller is designed. The newly developed plant model is used to design the feedforward controller and the conventional model is used for the design of feedback controller. The output of newly developed model is the displacement of objective lens and the output of conventional model is the focus error of the DVD focus servo system. The displacement of the objective lens is estimated by the dynamics model of the DVD focus servo system. The disturbance rejection performance of the two-degree-of freedom controller is compared with that of an LQG/LTR one.

• 한국영어학회지:영어학
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• 제1권2호
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• pp.273-293
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• 2001

In this paper, I examine the phenomenon of English depictive and resultative predications with specific attention given to the relation between accentual focus structure and argument structure. The goal is pursued primarily through a production experiment and analyses to establish the interconnection between focus and argument structure. The central claim is that the resultative predicate forms a complex predicate with a main verb, whereas the depictive predicate behaves as an adjunct in English secondary constructions. The result shows that the relationship between focus and accent depends at least in part on their argument structure, confirming that current focus theories about argument-head and adjunct-head structures in primary predication constructions can be extended to secondary predication constructions.

• 제어로봇시스템학회논문지
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• 제16권11호
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• pp.1082-1088
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• 2010

In this paper, we propose a new gel-type biomimetic variable-focus lens system. The miniaturization of conventional lens system is limited due to the use of a set of glass lenses for adjusting the focal length. Biologically inspired by the focus adjustment mechanism of the human eye, a gel-type single lens system with variable-focus is presented. The proposed system consists of a gel-type lens, mechanical parts such as body, rotation ring, and winding-type SMA actuator. In addition, the proposed system is designed to operate with a simple and miniaturized mechanical structure using a new attachment and driving mechanism. The focusing performance of the proposed system is verified through a series of experiments and measurements of the shape of the lens using tomography.

• 음성과학
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• 제15권2호
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• pp.7-19
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• 2008

Information structure can be conveyed by prosodic structure (Poser 1984 for Japanese; Inkelas and Leben 1990 for Hausa; Cho 1990 for Korean; Hayes and Lahiri 1991 for Bengali; Selkirk and Shen 1990 for Shanghai Chinese). Different subfields of linguistics and different theoretical perspectives suggest many distinct types of information structure: topic vs. comment, focus vs. background. old vs. new information, etc. The purpose of this paper is to investigate phonetic realizations of focus and topic among these information structures in Korean. For this purpose, we conduct a phonetic experiment where we examine duration, pitch and dephrasing in focus and topic structures. We make four findings through this study. First, duration of 'nun' varies depending on the information structure of the following constituent. Second, the degree of accentual phrase-initial rising is larger in contrastive topic and focused phrases than in neutral phrases. Third, a contrastive topic phrase always constitutes an Intonation Phrase on its own. Fourth, dephrasing occurs variously depending on gender and the number of the syllables within a phrase.

• 지식경영연구
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• 제21권2호
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• pp.101-118
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• 2020

The usage of emoticons used in the online environment continues to increase, and also the market for emoticons is growing rapidly. Emoticons go beyond simply conveying the meaning of a message and play various roles such as smooth communication, pursuit of fun, and intimacy. In this study, we first identify the factors that motivate users to use emoticons in an online messenger service, and then determine whether the derived factors have a significant effect on emoticon usage. Furthermore, based on Regulatory Focus Theory, we will distinguish between the group of promotion focus and the group of prevention focus to see how the influence of motives on emoticon usage differs.

• 음성과학
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• 제9권4호
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• pp.215-234
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• 2002

This study is designed for two purposes. The first one is to compare the realization and perception of English contrastive focus between Korean learners of English and native speakers of English. The second purpose is to study the phonological and phonetical features of contrastive focus by examining the results of production and perception experiments. English native speakers' results show that the English contrastive accents are generally accompanied by higher peak heights. The findings agree with the results of Bartels & Kingston (1994). Unlike native speakers of English, Korean speakers seem to be poor at relating the phonetical features of contrastive focus to their actual speech. Korean speakers' results are especially unsuccessful when the contrast is not distinctly grasped through syntactic structure, or when the function words are contrasted. Furthermore, Korean speakers' utterances tend to have pitch accents on every content word, whether the word is contrasted or not.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2006년도 추계학술대회 발표논문집
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• pp.75-79
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• 2006

In this study, we investigate ways that focus is realized in English utterances produced by native speakers of English and Korean learners. As compared to the previous studies which deal mainly with functional aspects of focus as a part of intonational structure, we attempt to provide more quantitative information on F0 and discover the extent to which Korean learners distinguish focus types in their English utterance production. On the test sentences designed to be disambiguated by correct focus realization, it is found that, even advanced-level Korean learners, unlike native speakers, hardly employ F0 to clarify the specific meaning of English utterances.

• 한국생산제조학회지
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• 제7권3호
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• pp.126-131
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• 1998

In computer vision system of modern industry precise measuring has lots of dfficulties because of measurement error due to distortion phenomenon. Among the difficulties, the distortion of edge is regraded as a dominent problem. which is caused by the vlurred image. The blurred image apperar when camera can not discriminate its precise focus. So. it is very important to decide focus of lens and to develop algorithm in order to correct distortion phenomenon. Thus. discrimination criteria obtained by image information of precise focus must be fixed in advance. The gray level histogram of image acquired from blurred edge tends to show a uniform distribution. Bimodal intensity histogram is related with condition of focus, and it is possible to find good condition of focus by using bimodal histogram of entropy.