• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.965-966
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.249-250
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• 2008

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.783-784
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• 2011

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.497-498
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• 2007

• Journal of Mechanical Science and Technology
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• 제20권1호
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• pp.51-58
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• 2006

To compensate for the motion errors in hydrostatic tables, a method to actively control the clearance of a bearing corresponding to the amount of error using actively controlled capillaries is introduced in this paper. The design method for an actively controlled capillary that considers the output rate of a piezo actuator and the amount of error that must be corrected is described. The basic characteristics of such a system were tested, such as the maximum controllable range of the error, micro-step response, and available dynamic bandwidth when the capillary was installed in a hydrostatic table. The tests demonstrated that the maximum controllable range was $2.4\;{\mu}m$, the resolution was 27 nm, and the frequency bandwidth was 5.5 Hz. Simultaneous compensation of the linear and angular motion errors using two actively controlled capillaries was also performed for a hydrostatic table driven by a ballscrew and a DC servomotor. An iterative compensation method was applied to improve the compensation characteristics. Experimental results showed that the linear and angular motion errors were improved to $0.12{\mu}m$ and 0.20 arcsec, which were about $1/15^{th}$ and $1/6^{th}$ of the initial motion errors, respectively. These results confirmed that the proposed compensation method improves the motion accuracy of hydrostatic tables very effectively.

• 한국항공우주학회지
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• 제38권5호
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• pp.437-444
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• 2010

본 논문에서는 한 개의 1축 가변속 CMG를 장착한 부족구동 위성의 자세제어 문제를 다루고 있다. 이러한 부족구동 위성의 경우, 전체 모멘텀이 영(zero)이 아니면 자세를 임의로 취할 수 없다. 위성을 안정화 시키려면 가변속 CMG가 위성의 모멘텀 방향으로 정렬해야 하기 때문이다. 4가지의 다른 장착형상을 고려하였으며, 각각에 대해 제어가능 모멘텀 영역을 분석하였다. 또한 각 형상에 대해 백스테핑 기법을 이용하여 안정한 자세제어 법칙을 제시하고 자세제어 특성을 비교하였다.

• 한국인터넷방송통신학회논문지
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• 제9권5호
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• pp.39-44
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• 2009

본 논문에서는 블루투스 모듈을 이용한 소프트웨어로 구현 가능한 모바일 컨트롤러 컨텐츠를 제안 개발한다. 개발된 시스템의 주요한 특징은 다음과 같다. 스마트폰과 노트북과의 통신은 블루투스 통신을 이용하였다. 클라이언트와 서버 두 가지 프로그램을 제작하여 클라이언트 측에서 블루투스 통신을 요청하고 서버 측에서 응답을 허락하도록 하였다. 이전 페이지와 다음 페이지로 이동하도록 컨트롤이 가능하며, GUI 환경으로 구현하여 이용자의 편리를 도모하였다. 성능평가 결과 제안 개발된 방법은 가격, 기능 및 휴대성 등에서 상대적으로 우수한 성능을 보여주고 있다.

• 아동학회지
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• 제11권1호
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• pp.100-114
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• 1990

The present research investigated scholastic self-concepts and attribution tendencies of institutionalized children in comparison with home-reared children. The subjects were 286 institutionalized and 327 home-reared fifth. sixth, seventh, and eighth grade children. Instruments were the Scholastic Self-Concept Test(Park. Lee. & Cho. 1980). the Attribution Tendency Test(Lee, 1983) and a questionnaire constructed by the researcher. Data were analyzed by ANOVA. Duncan's Test of Multiple Comparsion, and product- moment correlation coefficient(r). Findings showed that (1) the scholastic self-concept of institutionalized children was lower than that of home-reared children; (2) higher scholastic self-concept of institutionalized children was correlated with (i) higher degree of contentment with the institution. (ii) shorter length of residence in the institution. and (iii) older age at admission to the institution; (3) institutionalized children attributed achievement more to uncontrollable. external factors. while home-reared children attributed achievement more to controllable. internal factors; (4) institutionalized children with a lower degree of contentment with the institution attributed achievement to luck while those with a higher degree of contentment attributed achievement to ability; and (5) the higher the scholastic self-concept. the higher the tendency to attribute achievement to internal. controllable factors, and the lower the scholastic self-concept, the higher the tendency to attribute achievement to external, uncontrollable factors.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.234.2-234.2
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• 2015

Recently, the electromagnetically-induced transparency (EIT)-like effect in metamaterials has attracted enormous interest. Metamaterial analogs of EIT enable promising applications in slow-light devices, low-loss metamaterial, quantum optics, and novel sensors. In this work, we experimentally and numerically studied a bilayer metamaterial for controllable EIT-like spectral response at microwave frequencies. Bilayer metamaterial consists of two snake-shape resonators (SSRs) with one and two bars. The transmission spectra were measured in a frequency range of 4 - 8 GHz in an anechoic chamber at normal incidence. It is found that two SSRs in the metamaterial are activated in bright modes, and the coupling between two bright modes leads to the EIT-like effect, which results in the enhanced transmission at 5.61 GHz. Furthermore, we confirm that the EIT-like feature could be controlled by adjusting the geometric parameters of metamaterial structure. Our work provides a way to tunable EIT-like effect and various potential applications including filters, sensors, and other microwave devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.32-33
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• 2009

We propose viewing angle switchable liquid crystal display(LCD) associated with fringe-field switching (FFS) mode with high aperture ratio characteristic. This device is composed of R(red), G(green), B(blue), pixel and W(white) pixel in which R,G,B pixel shows image and white pixel for both viewing angle control and image. Conventional viewing angle controllable liquid crystal display has not transmittance because the liquid crystal only tilts up without rotates in viewing angle control region. In this paper, we suggested that the device has high transmittance characteristic because the LC directors are rotated in which viewing angle control region are generated fringe electric field.