• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 춘계학술대회 논문집
• /
• pp.513-517
• /
• 2004

The nature of the signals collected by an SEM(Scanning Electron Microscope) in order to form images are all dependent on the detector used to collect them, and the quality of an acquired image is strongly influenced by detector performance. Therefore, the development of detector with high performance is very important in pulling up the resolution of SEM. In this article, electron beam-specimen interactions, the detection principle of secondary electrons and backscattered electrons, and the structure of a conventional detector are described. The structure of an experimental apparatus for the future study on our hopeful novel electron detector is presented as well.

• 대한기계학회논문집
• /
• 제18권9호
• /
• pp.2272-2283
• /
• 1994

In scanning tunneling microscopy, the piezoelectric actuator is popuilarly used in stacked type as it can provide remarkable positioning resolution and stiffness. The actuator, however, exhibits a considerable amount of hystereic nonlinearity, resulting in losses of overall measuring accuracy when a linear model is used for its control and calibration, In this study, a nonlinear model is proposed for predicting the precise relationship between the input connand voltage and the output displacement of the actuator itself, cross-coupled electrical behaviours of the driving circuit with the actuator, and mechanical characteristics of the driven components of the actuator. Finally experimental results prove that the nonlinear model enhances the measuring of scanning tunneling microscopy by an order ten in comparison with a conventional linear model.

• 대한기계학회논문집B
• /
• 제28권2호
• /
• pp.154-159
• /
• 2004

A new microflow rate controller for medical injection was developed and evaluated. The flow rate was controlled by changing the friction depth as well as the friction length of the micro-channel. A precise micro-fabrication of the micro-channel was requested for an accurate flow control. The friction depth was inversely proportional to the friction length, which gives a linear flow control to the channel length. The channel groove was fabricated with a plastic material. A rubber containing silicone oil was covered over the groove, which satisfies both lubrication and leakage prevention. The flow controller was validated by performing the numerical simulation and experiment. A good agreement was shown between computation and experiment.

• 한국정밀공학회지
• /
• 제14권11호
• /
• pp.102-109
• /
• 1997

A two-degree-of freedom (TDF) $H_{\infty}$controller for a seeker scan loop is presented for the purpose of improving scanning performances. The perturbed plant model is characterized via the normalized coprime factorization. The TDF $H_{\infty}$controller is designed based on the loop shaping design procedure and model matching approach, and its performances are evaluated and compared with those of a previous work. It is demonstrated that the proposed TDF $H_{\infty}$controller is more effective to the control of the seeker scan loop than the previous controller.oller.

• 한국정밀공학회지
• /
• 제25권4호
• /
• pp.53-60
• /
• 2008

Electron detectors used in scanning electron microscope accept electrons emitted from the specimen and convert them to an electrical signal that, after amplification, is used to modulate the gray-level intensities on a cathode ray tube, producing an image of the specimen. Electron detector is one of the key components dominating the performance of scanning electron microscope so that the development of electron detectors having high performance is indispensable to acquire high quality images using scanning electron microscope. In this paper, we designed and manufactured an electron detector and conducted a couple of image capture experiments using it. In particular, scintillator which generates light photons when it is struck by high-energy electrons was manufactured and experimental studies on the optimization of manufacturing condition was carried out. From experiments to evaluate the performance of our detector, it was verified that the performance of our detector is equivalent to or better than that of the conventional one.

• 대한기계학회논문집
• /
• 제17권11호
• /
• pp.2730-2741
• /
• 1993

A mathematical model of the seeker scan-loop which is composed of a spin-stabilized gyroscope and its driving signal processors is derived. The derived model has a transmission zero pair on the imaginary axis near to the required bandwidth. The LQG/LTR design methodology is evolved for the derived scan-loop model. To implement the designed LQG/LTR compensator to the actual plant, the compensator order is reduced using the internally balanced realization method. The performances of the LQG/LTR compensator are tested and compared with those of the P-control. Especially, stability-robustnessexperiments for model uncertainties represented in the form of time-delays are performed. It is demonstrated that the LQG/STR compensator is actually very robust to model uncertainties.

• 한국정밀공학회지
• /
• 제16권3호통권96호
• /
• pp.180-188
• /
• 1999

${\mu}$-synthesis is applied to design a robust controller for a seeker scan loop system which has model uncertainty and is subject to a external disturbance due to abrupt missile maneuver. The issue of modelling a real-valued parametric uncertainty of a physical seeker scan loop system is discussed. The two-degree-of-frame control structure is employed to obtain better performance. It is shown that ${\mu}$-synthesis provides a superior framework for the robust control design of a seeker scan loop system which exhibits robust performance. The proposed robust control system satisfies design requirements, and especially shows good scanning performances for conical and rosette scan patterns despite parametric uncertainty in real system model.

• Pediatric Infection and Vaccine
• /
• 제18권2호
• /
• pp.124-134
• /
• 2011

목 적:우리나라의 B형 간염 조절을 위한 초창기 예방접종 정책과 1회용 주사기를 포함한 혈액매개질환의 감염원이 될 수 있는 기구 사용 정책에 관한 자료를 수집, 정리하여 향후 정책 수립 및 평가에 활용할 수 있도록 하였다. 방 법:국내 학회지 또는 논문, 정부 웹사이트, 전산화된 주요 일간신문 등을 검색하여 수집된 자료들의 내용을 확인하였다. 자료의 내용에 따라 정부의 B형 간염 조절 정책, 학교에서의 B형 간염 단체 예방접종 사업, B형 간염 백신 사용 상황, 1회용 주사기를 포함 혈액매개질환의 전파 가능성이 있는 기구 사용에 관한 정책 등 네 가지 주제로 나누어 각각에 대해 시기별 정책 변화를 정리하였다. 결 과: 1980년대 초 B형 간염에 대한 사회적 관심이 컸기 때문에 B형 간염 백신이 신속히 도입, 개발되었으며, 1983년 말에 'B형 간염 퇴치를 위한 5개년 계획'이 수립되어 1984-5년 2년간에만 B형 간염 백신을 접종한 사람은 약 600만명이었다. 그러나 접종 대상이 신생아가 아닌 성인에 초점을 맞추었기에 전문가들의 반론에 따라 2년만에 계획은 백지화되었다. 이후 학교 단체 예방접종 사업이 진행되고, 1995년에는 국가 필수예방접종에 포함되는 등 신생아 중심의 예방접종 정책이 유지되었다. 1회용 주사기의 사용은 1980년대 초부터 권고 되었으나 1985년이 돼서야 법제화되었다. 결 론:우리나라에서의 B형 간염 감염 관리에 대한 성공 요인은 B형 간염 백신의 조기 도입 및 대량 접종, 높은 접종률, 1회용 주사기 사용 등이 종합적으로 작용하여 이루어진 것이라 생각된다. 그러나 이를 뒷받침할만한 공식적 자료가 너무 부족하다. 따라서 정부가 보유하고 있는 모든 감염 관련 자료들의 정리와 전산화 작업이 매우 시급하다고 여겨진다.

• 전자진흥
• /
• 제5권4호
• /
• pp.99-102
• /
• 1985

• 한국어업기술학회:학술대회논문집
• /
• 한국어업기술학회 2002년도 춘계 수산관련학회 공둥학술발표회
• /
• pp.325-326
• /
• 2002