• 한국콘텐츠학회논문지
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• 제5권2호
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• pp.267-274
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• 2005

본 논문에서는 별도의 센서 없이 영상만을 이용하여 실시간으로 손 영상을 인식하는 알고리즘을 제안한다. 손은 모양이 매우 복잡하기 때문에 2차원 모양의 불변량에 해당하는 에지의 방향성 히스토그램을 이용하여 인식을 행한다. 이 방법은 복잡한 배경에서 색상정보를 이용하여 손 영역이 정확히 추출되며 계산량이 적고 조명변화에 덜 민감하기 때문에 실시간 손 영상 인식에 적합하다. 본 논문에서는 손의 모양제시 방향이 변하는 경우에도 인식을 가능하게 하기 위해 주성분 분석법을 사용하여 인식오차를 줄이는 방법을 기술한다. 이 방법을 사용함으로써 손 영상이 3차원적으로 회전에 의해 변하는 경우도 인식가능하게 되었다. 또한 에지방향성 데이터를 이용하기에 주성분 공간 생성 시간을 현저히 줄이게 되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.438-438
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• 2011

White light-emitting diodes (LEDs), the so-called next-generation solid-state lighting, offer benefits in terms of reliability, energy-saving, maintenance, safety, lead-free, and eco-friendly. Recently, rare-earth-doped oxynitride or nitride compounds have attracted a great deal of interest as a photoluminescent material because of their unique luminescent property, especially for white LEDs applications. Ce doped ${\beta}$-SiAlON has been studied as a wavelength conversion phosphor in white LEDs thanks to its high absorption rates, high quantum efficiency, and excellent thermal stability. Previously researches were not enough to understand the detail mechanism and characteristics of ${\beta}$-SiALON. The bandgap structures and electronic structures were not exact due to limitation of calculation methods. In this study, to elucidate the Ce doping effect on the SiAlON system, accurate band structures and electronic structure of the Ce doped ${\beta}$-SiAlON was intensively investigated using density functional theory calculations. In order to get a better description of the band gaps, MBJLDA method were used. We have found a single Ce atom site in ${\beta}$-SiAlON super cell. Furthermore, the density of state, band structure and lattice constant were intensively investigated.

• 한국음향학회지
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• 제6권1호
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• pp.48-57
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• 1987

냉장고에 있어서 소음의 주발생원이 압축기라는 것은 잘 알려져 있는 사실이며 최근 제품의 경량화와 고급화 추세에 따라 그 영향이 더욱 증대되고 있다. 본 연구에서는 이러한 소음을 방지 또는 감소시키기 위하여 냉장고용 압축기에 대한 음압과 음향인텐시티를 측정하여 소음의 방사특성을 파악하였으며 이를 규명하기 위하여 실험적 모우드 해석법을 압축기 구조물에 대하여 적용하였다. 연구결과, 압축기 내부의 모우터 구동에 의해 발생한 진동이 스프링에 의해 효과적으로 절연되지 못하고 있으며 압축기의 shell과 mounting도 소음에 크게 기여하고 있음을 알았다.

• 디지털산업정보학회논문지
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• 제15권4호
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• pp.149-157
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• 2019

In case of reading passport using a smart phone in contrast with a dedicated passport reading system, MRZ(Machine Readable Zone) character recognition can be hard when the character strokes were broken, touched or blurred according to the lighting condition, and the position and size of MRZ character lines were varied due to the camera distance and angle. In this paper, the effective recognition algorithm of the passport MRZ information using a combined neural network recognizer of CNN(Convolutional Neural Network) and ANN( Artificial Neural Network), is proposed under the various sized and skewed passport images. The MRZ line detection using connected component analysis algorithm and the skew correction using perspective transform algorithm are also designed in order to achieve effective character segmentation results. Each of the MRZ field recognition results is verified by using five check digits for deciding whether retrying the recognition process of passport MRZ information or not. After we implement the proposed recognition algorithm of passport MRZ information, the excellent recognition performance of the passport MRZ information was obtained in the experimental results for PC off-line mode and smart phone on-line mode.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2017년도 추계학술발표대회
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• pp.891-894
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• 2017

Lane detection algorithms became a key factor of advance driver assistance system (ADAS), since the rapidly increasing of high-technology in vehicles. However, one common problem of these algorithms is their performance's instability under various illumination conditions. We recognize a feasible complementation between image processing and color science to address the problem of lane marks detection on the road with different lighting conditions. We proposed a novel lane detection algorithm using the attributes of a uniform color space such as $CIEL^*C^*h$ with the implementation of image processing techniques, that lead to positive results. We applied at the final stage Clustering to make more accurate our lane mark estimation. The experimental results show the effectiveness of our method with detection rate of 91.80%. Moreover, the algorithm performs satisfactory with changes in illumination due to our process with lightness ($L^*$) and the color's property on $CIEL^*C^*h$.

• 조명전기설비학회논문지
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• 제25권6호
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• pp.9-17
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• 2011

The high-power LED (Light Emitting Diode) which is recently gaining popularity as a digital light source has such advantages as low power consumption, long life, fast switching speed, and high efficiency. Thus, many efforts are being made to use the high-power LEDs for general lighting. This paper proposes LED driving circuit uses a DC/DC converter that can recover energy to compensate for the current variations caused by changes in LED equivalent resistance following a temperature change instead of serial resistance. The maximum input voltage of this DC/DC converter has low voltage variations by temperature change when the rated current is formed. In order to return current to the input side, we need a high boosting at low power. Thus, to improve the low efficiency of power converter, the power converter can be configured in such a way to gather the powers of low-capacity DC/DC converters and return the total power. Experiments showed that the proposed system improved efficiency compared to the conventional LED drive using the existing DC/DC converter.

• 전력전자학회논문지
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• 제20권5호
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• pp.395-401
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• 2015

This paper proposes a new bidirectional DC-DC converter with high efficiency. The proposed converter is composed of a flyback and a tapped-inductor boost converter to satisfy extreme operating conditions with low cost. The outputs are connected in series to achieve a high-voltage step-up. In the reverse direction, the proposed converter has an extreme step-down voltage. In this study, the proposed converter was employed with a 100 W hardware prototype. To design the controller, a small-signal transfer function of the proposed converter is derived. For PV power conditioning systems, a maximum power point tracking method is applied with perturb and observe method. To verify the operation of the bidirectional power flow, the current controller is applied. All of the controllers are employed with a digital signal processor.

• 한국전기전자재료학회논문지
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• 제28권4호
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• pp.271-275
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• 2015

The floodlighting assists the pilot in taxiing the aircraft into and out of the final parking position and provide lighting suitable for passenger to embark and debark and for personnel to load and unload cargo. It is composed of sodium lamps which is consuming high energy. It needs to develop a dedicated LED lamp to replace the existing lamps. In this paper, We propose a suitable asymmetric angle of LED lamps to avoid a pilot's glare and to meet the standard illumination. For this, we analyze asymmetric angle of sodium lamps which are using in airport and confirm whether the illumination distribution and glare index meet the relating standards by using simulation method. Also, we study the needs of asymmetric characteristics of LED ramp by simulating the LED lamps with and without asymmetric characteristics of ramp respectively. With the simulation result, finally we propose the best asymmetric angle of LED lamp to meet the average illumination standard, and avoid a pilot's glare.

• 전자공학회논문지
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• 제51권7호
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• pp.89-95
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• 2014

주위 밝기 및 환경에 따라서 LED 조명등의 밝기를 조절하기 위한 장치를 PWM 기술과 전력 소자를 이용하여 구현하였다. 주위의 광량 측정을 위하여 CdS 센서를 사용하였으며, PWM 신호 생성을 위하여 MCU를 사용하여 제어 보드를 설계한 다음 광량에 따라 듀티비를 조절하였다. 고전압, 대전류를 필요로 하는 LED 조명등을 디밍하기 위하여 전력 소자를 사용하여 DC 전원장치의 출력을 스위칭하였으며, PowerMOSFET, IGBT, PowerBJT를 각각 사용하여 특성을 서로 비교하였다. 실험결과 선형성 면에서는 IGBT가 양호하였으나, 효율 및 가격 면까지 고려하면 PowerBJT도 우수한 특성을 보였다.

• 디지털콘텐츠학회 논문지
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• 제10권2호
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• pp.319-326
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• 2009

본 논문에서는 별도의 센서를 부착하지 않고 영상만을 이용하여 실시간으로 손 형상을 인식하는 알고리즘에 대해 기술한다. 손은 형상이 매우 복잡하기 때문에 2차원 형상의 불변량에 해당하는 에지의 방향성 히스토그램을 이용하여 인식을 행한다. 이 방법은 복잡한 배경에서 피부색을 지닌 손 영역이 정확히 추출되며 손 형상을 인식하는데 있어서 수행속도가 빠르고 조명변화에 덜 민감하기 때문에 실시간 손 형상 인식에 적합하다. 본 논문에서는 손의 형상에서 방향이 틀어지는 경우에도 인식을 가능하게 하기위해 주성분 분석법을 사용하여 인식오차를 줄이는 방법을 기술한다. 이 방법을 사용함으로써 손 영상이 3차원적으로 회전에 의해 변하는 경우도 인식가능하게 되었다. 본 논문에서 제안하는 방법은 가정용 가전제품이나 게임을 제어하는 실시간 휴먼 인터페이스 제작에 사용 할 수 있다.