• Journal of Power Electronics
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• 제16권2호
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• pp.815-822
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• 2016

The efficiency of light-emitting diode (LED) devices is a significant factor that reflects the capability of these devices to convert electrical power into optical power. In this study, a method for estimating the efficiency of LED devices is proposed. An efficiency model and a heat power model are established as convenient tools for LED performance evaluation. Such models can aid in the design of LED drivers and in the reliability evaluation of LED devices. The proposed estimation method for the efficiency and heat power of LED devices is verified by experimentally testing two types of commercial LED devices.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권1호
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• pp.8-15
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• 2004

In order to scheme the optimal assumption that satisfies the travel demand, it should be review the elements that affect on determining the headway, which are signal systems, line shape, vehicle(Light Rail Transit) performance, and so on. When applying the conventional signal systems, including Fixed Block System and Moving Block System, It was confirmed whether or not satisfy the requirements of target line with the way of a numerical formula reviewing and Train performance Simulation on the main line, station, depot, and so forth. Therefore, it should be used as references that decide target line and each sub-system after identifying the compliances for Minimum Headway to Moving Block System.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.319-320
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• 2006

In this paper, automatic sunvisor system is introduced for driver's safety and convenience. This system has the mechanism which keeps the sun off without obstruction of driver's sight. The mechanism can make the sunvisor move forward or rotate left while remaining inside inner roof. The control system consists of a CPU, a motor driver, light sensors, and the algorithm that can control the movement of sunvisor efficiently. When the light sensors take the sun light, they give the signal to the CPU and the CPU calculates the best position of the sunvisor with the information of driver's eyes height. Then, the CPU gives the signal to motors that can move the sunvisor.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2001년도 하계 학술대회 논문집(KISPS SUMMER CONFERENCE 2001
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• pp.265-268
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• 2001

내용에 기반한 동영상 검색에서, 대표 프레임을 자주 이용하는데, 이를 위해 우선적으로 동영상의 장면변화를 검출하는 기술이 필요하다. 일반적으로 컬러 히스토그램 비교방법이 많이 쓰이나, 급격한 조명변화에 민감하고 컬러 히스토그램 분포가 비슷한 부분의 장면전환을 놓칠 수 있다는 단점이 있다. 본 논문에서는 컬러 히스토그램 비교방법과 엔트로피를 복합적으로 이용하여 조명변화에 의해 장면전환이 잘못 검출되는 것을 막을 수 있다. 실험을 통해 제안한 방법은 컬러 히스토그램 비교방법보다 조명변화에 보다 감격함을 확인할 수 있었다.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2001년도 하계 학술대회 논문집(KISPS SUMMER CONFERENCE 2001
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• pp.241-244
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• 2001

A various color device became generalization. Therefore, request about expression of correct color is increased. Device independent color reproduction system acquires and reproduce color of object regardless characteristic of Input/Output device. Human visual system is partially adapted to the CRT monitor's white point and the ambient light. The visual experiments were performed on the effect of the ambient lighting under mixed chromatic adaptation. In this paper, It was found that human visual system is 40% to 60% adapted to CRT monitor's white point light and the rest to ambient light.

• Journal of the Optical Society of Korea
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• 제16권2호
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• pp.101-106
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• 2012

We demonstrate a cost effective broadcast signal transmission at 1.25-Gb/s with 100 GHz channel spacing based on a broadband light source (BLS) for a wavelength division multiplexing-passive optical network (WDM-PON). The BLS is implemented by using mutually injected Fabry-Perot laser diodes (MI F-P LDs). The error-free transmission without a forward error correction (FEC) is achieved by its low relative intensity noise (RIN). The number of usable modes is determined by RIN and/or extinction ratio (ER) in the spectrum sliced light output.

• 한국전자파학회논문지
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• 제14권5호
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• pp.466-471
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• 2003

본 논문에서는 포토다이오드의 방향이 항상 신호광의 입사방향과 일치하도록 수광각을 자동정렬하는 광검출기의 구조를 새로이 소개한다. 이 광검출기에서는 신호광을 수신하기 위한 포토다이오드 1개를 중심으로 $\Phi$-축상에 4개의 포토다이오드와 $\theta$-축상에 2개의 포토다이오드를 추가로 배열하여 각각 $\Phi$-축과 $\theta$-축에 해당하는 모터를 구동한다. 이 광검출기는 임의의 모든 방향으로부터 입사하는 신호광에 대하여 약 1초 이내에 수신방향을 신호광 쪽으로 일치시킨다.

• 한국전자통신학회논문지
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• 제11권12호
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• pp.1245-1250
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• 2016

본 연구에서는 영상처리를 이용하여 레이저 포인터를 연구하였다. 레이저 포인터는 영상처리로 빛을 추적하고, 추적된 신호를 송신부에 (레이저 포인터) 수신한다. 레이저 포인터에 수신된 영상신호 이용하여 마우스 기능 및 지우기, 쓰기, 창 변환, 글씨 색 변경을 실행한다. 즉, 한 자리에서 포인터와 마우스 기능을 실행할 수 있는 스마트 레이저 포인터 시스템을 연구하였다.

• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.222-226
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• 2011

We demonstrated the feasibility of an amplified wavelength-division multiplexed passive optical network (WDM-PON) architecture based on broadband light source (BLS) seeded optical sources and a novel bidirectional reach extender. Our bidirectional reach extender could provide an amplification of both downstream and upstream signals as well as a BLS output for the upstream WDM signal generation. An error-free 1.25 Gb/s signal transmission over a 100-km long single-mode fiber was achieved in a bidirectional WDM-PON using BLS seeded reflective semiconductor optical amplifier (RSOA) sources.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.629-632
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• 1989

The scattered light intensity from a spherical particle passing through the cross-over region of two coherent laser beams, varies periodically. Photodetection of this light beams produces a periodic signal of varying amplitude. The phase of the signal varies with the particle size and refractive index, the beam crossing angle and wavelength, and the position and size of the scattered ligth collecting aperture. In this paper the phase variation with respect to the particle absorptive index of retraction, collecting lens size and beam crossing angle is calculated using both Mie scattering theory and reflection theory. The two theories show good agreement in phase predictions, especially for large absorptive indices and for small collection lenses. Both theories predict phase to be inversely proportional to the beam crossing angle.