• 대한전기학회논문지
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• 제36권10호
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• pp.703-712
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• 1987

A position detection method for 2 phase bifilar permanent magnet step motors is proposed. The back emfgenerated on 2 phase windings by rotor permanent magnet is calculated using motor terminal voltage and current by analog circuit, and the rotor position output is obtained from tese back emf signals through some logical manipulation circuit. This position detector functionally acts like a 2 channel optical incremental encoder, and it is also shown by experimental results that it works well over wide range of speed or under resonant condition where the rotor rings around the detent position. Its resolution is twice of the number of steps per revolution. Bu software implemented on micro-processor, the reliability of position output is enhanced, detecting and correcting error dut to external and/ or internal noise.

• International Journal of Oral Biology
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• 제43권2호
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• pp.53-59
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• 2018

In order to understand biological phenomena accurately, single molecule techniques using a physical research approach to molecular interactions have been developed, and are now widely being used to study complex biological processes. In this review, we discuss some of the single molecule methods which are composed of two major parts: single molecule spectroscopy and manipulation. In particular, we explain how these techniques work and introduce the current research which uses them. Finally, we present the oral biology research using the single molecule methods.

• Bulletin of the Korean Chemical Society
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• 제24권5호
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• pp.600-604
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• 2003

The light pressure force from an optical standing wave (SW) can focus an atomic beam to submicrometer dimensions. To make the best of this technique it is necessary to find a set of optimal experimental parameters. In this paper we consider theoretically the chromium atoms focusing and demonstrate that the focusing performance depends not only on the strength of but also on the time atoms take to traverse the force field. The general conclusions drawn can easily be applied to other atoms. To analyze the problem we numerically integrate a coupled time-dependent $Schr{\"{o}}dinger$ equation over a wide range of experimental parameters. It is found that an optimal atomic beam speed-laser intensity pair does exist, which could give substantially improved focusing over the one with the experimental parameters given in the literature. It is also shown that the widely used classical particle optics approach can lead to erroneous predictions.

• 한국광학회지
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• 제12권6호
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• pp.437-445
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• 2001

We examine theoretically the properties of the force on Mie particles induced by evanescent fields at a system of multilayer films (including a metal film), at which the surface plasmon resonance is excited by a p-polarized plane electromagnetic wave. An expression of the surface plasmon-coupled evanescent fields produced in Kretschmann (or Sarid) geometry is expanded in terms of vector spherical wave functions, while multiple reflections between the Mie particle and the metal boundary are taken into account. The Cartesian components of the force on Mie particles by the evanescent fields are analytically formulated and numerically evaluated. The force components are increased by one or two orders of magnitude at metal boundaries over those at dielectric boundaries. As a result, we can confirm the possibility of stable manipulation or rotation of a finite-sized object by forces of surface plasmon-coupled evanescent fields.

• 방송공학회논문지
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• 제7권3호
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• pp.248-261
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• 2002

본 논문에서는 스테레오 비젼 시스템의 3차원 정보에 의해 가변되는 윈도우 마스크와 광 BPEJTC(binary phase extraction joint transform correlator)를 이용하여 스테레오 카메라를 제어하는 새로운 3차원 물체추적 시스템을 제안하였다. 즉, 스테레오 비젼 시스템의 구성 요소에 의해 3차원 정보인 추적 물체까지의 거리 정보를 쉽게 구할 수 있고, 이 거리 정보로 윈도우 마스크를 가변 시켜 추적물체 영역을 추출할 수 있다. 이 추적물체 영역은 다음 기준영상으로 갱신하여 사용된다. 그리고 이 기준영상과 스테레오 입력 영상간에 광 BPEJTC를 실행하여 추적 물체의 위치 값을 구하고. 이 값으로 스테레오 카메라의 주시각과 팬/틸트를 제어하여 3차원 물체추적이 이루어진다. 실험 결과 제안한 알고리즘은 스테레오 입력 영상에서 배경잡음과 관계없이 추적 물체영역을 추출하여 3차원 물체추적이 가능하고, 이의 구현으로 3차원 원격작업 시스템이나 적응적인 3차원 물체 추적기 등의 구현 가능성을 제시하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.399-399
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• 2008

Synthesis and characterization of ZnO structure such as nanowires, nanorods, nanotube, nanowall, etc. have been studied to multifunctional application such as optical, nanoscale electronic and chemical devices because it has a room-temperature wide band gap of 3.37eV, large exiton binding energy(60meV) and various properties. Various synthesis methods including chemical vapor deposition (CVD), physical vapor deposition, electrochemical deposition, micro-emulsion, and hydrothermal approach have been reported to fabricate various kinds of ZnO nanostructures. But some of these synthesis methods are expensive and difficult of mass production. Wet chemical method has several advantage such as simple process, mass production, low temperature process, and low cost. In the present work, ZnO nanorods are deposited on ITO/glass substrate by simple wet chemical method. The process is perfomed by two steps. One-step is deposition of ZnO seeds and two-step is growth of ZnO nanorods on substrates. In order to form ZnO seeds on substrates, mixture solution of Zn acetate and Methanol was prepared.(one-step) Seed layers were deposited for control of morpholgy of ZnO seed layers by spin coating process because ZnO seeds is deposited uniformly by centrifugal force of spin coating. The seed-deposited samples were pre-annealed for 30min at $180^{\circ}C$ to enhance adhesion and crystallinnity of ZnO seed layer on substrate. Vertically well-aligned ZnO nanorods were grown by the "dipping-and-holding" process of the substrates into the mixture solution consisting of the mixture solution of DI water, Zinc nitrate and hexamethylenetetramine for 4 hours at $90^{\circ}C$.(two-step) It was found that density and morphology of ZnO nanorods were controlled by manipulation of ZnO seeds through rpm of spin coating. The morphology, crystallinity, optical properties of the grown ZnO nanostructures were carried out by field-emission scanning electron microscopy, high-resolution electron microscopy, photoluminescence, respectively. We are convinced that this method is complementing problems of main techniques of existing reports.

• 대한기계학회논문집A
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• 제36권5호
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• pp.481-486
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• 2012

본 논문에서는 대변위 구동이 가능한 구동기의 설계를 위해 기존의 전자기력 구동기에 비해 낮은 스프링 상수를 갖는 굴곡형 스프링을 적용하고, 변위가 발생하는 방향으로만 로렌츠힘이 생기도록 굴곡형 스프링의 일부분만 자기장에 노출시키는 구동기를 제안한다. 굴곡형 스프링의 양쪽 부재가 자기장에 노출된 구조(prototype F)와 굴곡형 스프링의 한쪽 부재만을 자기장에 노출시킨 구조(prototype P)를 설계하고, 제작하여 실험한 결과 prototype P 가 굴곡형 스프링의 양쪽 부재를 자기장에 노출시킨 prototype F의 구동성능에 비해 $16.9{\pm}1.2%$의 진폭 증가를 보임을 실험적으로 검증하였다. 제안된 구동기는 제한된 면적 내에서 작은 전류(<50mA)와 작은 자기장(<0.3T)으로 대변위 구동을 가능케 하여 광 스위치 또는 광 단속기 등에 응용이 가능하다.

• 한국게임학회 논문지
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• 제17권3호
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• pp.53-62
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• 2017

VR 콘텐츠 조작 장비는 높은 가격을 요구하기 때문에 개인이 접하기 쉽지 않다. 특히 VR 콘텐츠 중 사용자의 모션을 추적하는 시스템의 경우 일반적으로 적외선 카메라를 사용하는 별도의 광학 센서 장비를 사용한다. 광학 센서 장비들은 단일기기만 사용할 경우 회전 동작 추적을 할 때 측정 가능한 범위가 측정 방향에 의존적이라는 단점이 있다. 위와 같은 문제들을 해결하기 위해 본 논문에서는 별도의 광학 센서 장비 없이 일반적으로 대중이 보유하고 있는 장비인 스마트폰의 관성센서를 사용하여 측정 방향에 구애 받지 않고 사용자의 회전 동작을 추적할 수 있음을 보인다. 그리고 립모션을 사용한 시스템을 참조 시스템으로, 스마트폰을 사용한 시스템을 평가 시스템으로 정하여 두 시스템의 사용자 만족도를 비교하여 평가 시스템의 유용성을 검증한다.

• 한국표면공학회지
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• 제52권2호
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• pp.90-95
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• 2019

Methylammonium lead bromide ($MAPbBr_3$) has attracted a lot of attention due to their excellent optoelectronic properties such as the compositional flexibility relevant to photoluminescence (PL) and UV-Vis absorbance spectrum, high diffusion length, and photoluminescence quantum yield (PLQY). Despite such advantages of organic-inorganic perovskite materials, more systematic study on manipulation of their optoelectronic properties in homo- or heterovalent metal ions doped halide perovskite nanocrystals is lacking. In this study, we systematically investigated the optical properties of colloidal $CH_3NH_3Pb_{1-x}Sn_xCl_{2x}Br_{3-2x}$ particles by addition of $SnCl_2$ into the typical methylammonium lead tribromide ($CH_3NH_3PbBr_3$) precursor solution. We found that only 1% addition of $SnCl_2$ shows a significant blue-shift from 540 nm to 420 nm in UV-Vis absorbance spectrum due to the strong quantum confinement effect. Furthermore, continuous blue-shift in photoluminescence spectra was observed as the amount of Cl increases. These experimental results provide new insights into the replacement of Pb within $MAPbBr_3$, required for the broadening of their application.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권6호
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• pp.428-434
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• 2004

Coarse clumping of solid materials within diseased biological cells can have a marked influence on the light scattering pattern. Perturbations in refractive index lead to distinct varia­tions in the cytometric signature, especially apparent over wide scattering angles. The large dynamic range of scattering intensities restricts collection of data to narrow angular intervals be­lieved to have the highest potential for medical diagnosis. We propose the use of an interfer­ence filter to reduce the dynamic range. Selective attenuation of scattering intensity levels is expected to allow simultaneous data collection over a wide angular interval. The calculated angu­lar transmittance of a commercial shortwave-pass filter of cut-off wavelength 580 nm indicates significant attenuation of scattering peaks below ${\~}\;10^{circ}$, and reasonable peak equalization at higher angles. For the three-dimensional calculation of laser light scattered by cells we use a spectral method code that models cells as spatially varying dielectrics, stationary in time. How­ever, we perform preliminary experimental testing with the interference filter on polystyrene microspheres instead of biological cells. A microfluidic toolkit is used for the manipulation of the microspheres. The paper intends to illustrate the principle of a light scattering detection system incorporating an interference filter for selective attenuation of scattering peaks.