• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.332-334
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• 2012

This study investigates records about state systems which were installed to manage aids to navigation workings related to ship and navigation in Korea. It shows the transition process from signal-fire that was used for safe sailing in the three kingdom period to the oil lamp, acetylene gas light, electric light and the LED lamp have been used as a light source for the lighthouses since the modern age.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.106-110
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• 2005

In this paper, LED traffic signal lamp's operating circuit using Flyback converter and PFC IC has been presented. Most power conversion circuits use PFC IC for Power Factor Correction. The design parameter's value of Flyback converter has been proposed and the error amplifier which regulates the output voltage has been designed Besides, the under voltage protection circuit and the over voltage protection circuit for protecting the operating circuit kin unbalance of common electric power source and the temperature compensation circuit for fixed optical output power have been proposed.

• IEIE Transactions on Smart Processing and Computing
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• v.6 no.4
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• pp.269-275
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• 2017

Automatic vehicle detection is a very important function for autonomous vehicles. Conventional vehicle detection approaches are based on visible-light images obtained from cameras mounted on a vehicle in the daytime. However, unlike daytime, a visible-light image is generally dark at night, and the contrast is low, which makes it difficult to recognize a vehicle. As a feature point that can be used even in the low light conditions of nighttime, the rear lamp is virtually unique. However, conventional rear lamp-based detection methods seldom cope with atypical lamps, such as LED lamps, or flashing turn signals. In this paper, we detect atypical lamps by blurring the lamp area with a low pass filter (LPF) to make out the lamp shape. We also propose to detect flickering of the turn signal lamp in a manner such that the lamp area is vertically projected, and the maximum difference of two paired lamps is examined. Experimental results show that the proposed algorithm has a higher F-measure value of 0.24 than the conventional lamp pairing-based detection methods, on average. In addition, the proposed algorithm shows a fast processing time of 6.4 ms per frame, which verifies real-time performance of the proposed algorithm.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.663-671
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• 2014

LED lamp arrangement is a critical issue in indoor visible light communication (VLC) system. In this paper, we analyze the illumination distribution under the arrangement of $2{\times}3$ and propose a method to find the optimal lamp arrangement. The method, based on the MIMO (Multiple Input/Multiple Output) system model and taking the first order reflection into consideration, enables accurate analysis of the arrangement of the LED lamps for any room. The studies show that under the optimal arrangement the uniformity of illumination is improved from 0.55 to 0.86, which guarantees that users can get almost equal lighting effects, no matter where they locate themselves. At the same time, the RMS delay spread distribution which is used to evaluate the inter-signal-interference (ISI) is analyzed, and the simulation results indicate that the optimal arrangement also can improve the communication quality by reducing the fluctuation of the RMS delay spread.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.125-134
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• 2016

We propose an efficient high voltage level shifter for a high side Buck converter driving a light-emitting diode (LED) lamp. The proposed circuit is comprised of a low voltage pulse width modulation (PWM) signal driver, a coupling capacitor, a resistor, and a diode. The proposed method uses a property of a PWM signal. The property is that the signal repeatedly transits between a low and high level at a certain frequency. A low voltage PWM signal is boosted to a high voltage PWM signal through a coupling capacitor using the property of the PWM signal, and the boosted high voltage PWM signal drives a p-channel metal oxide semiconductor (PMOS) transistor on the high side Buck converter. Experimental results show that the proposed level shifter boosts a low voltage (0 to 20 V) PWM signal at 125 kHz to a high voltage (370 to 380 V) PWM signal with a duty ratio of up to 0.9941.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.178-182
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• 2014

This paper investigates the lighting environment of railway system which are mainly used in KTX, Saemaul and Mugunghwa. When lighting used in KTX such as fluorescent lamp and incandescence is being replaced with LED lamp, illumination load of each railroad vehicle has been compared. The comparison result shows that the reduction of power consumption is 43.34% before and after the change. Also it has been performed the economic evaluation.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.157-159
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• 2007

For a vessel to safely navigate on the ocean, it is required to check the vessel position as frequently as possible. When a vessel navigates oil the ocean or entering/leaving a port, the target area such as islands, points and mountain peak, etc. are used. However, when such target are not available or when vessel navigates in night time, installed artificial navigation aid facilities help successful vessel navigation. Light Wave Aid helps to confirm a position to the navigator directly and quickly. So, the synchronous light to display the accurate signal has wide applications. However, lantern domestic industry is small, and most of the products show non-compatibility. Consequently, this paper presents the synchronous lighting using UTC of GPS, which maintains compatibility with different lanterns. Also, by replacing conventional electric bulb with LED lamp, simple and efficient lighting system is obtained.

• Journal of Sensor Science and Technology
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• v.21 no.6
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• pp.429-433
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• 2012

In this paper, we reduced the optical noise interference in a visible light communication system using two color LEDs. In the transmitter, the original and the inverted signals of the transmitted data modulated a red LED and a blue LED, respectively. In the receiver, a differential detector which is composed of two photodetectors and an optical red filter detected the mixed signal radiated from the two LEDs. In an environment that the optical noise from a fluorescent lamp exists, the signal-to-noise ratio in this system was improved by about 20dB compared to that in the conventional system which uses a single LED and a single photodetector.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.2
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• pp.123-129
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• 2009

In this study, SMPS to drive LED traffic signal light for the railroad and airport was designed and its electrical characteristics was measured. The output voltage, output current and its power efficiencies to the input voltage 8~12VAC and 8~16VDC were 6VDC, 1.85ADC and >70%, respectively. Also the power factors of the SMPS were above 0.75 in the AC input voltage range.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3144-3146
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• 1999

$8{\sim}12$인치의 원형(또는 사각) PCB 기판에 수백 개의 고휘도 반도체 발광 다이오드(Light Emitting Diode. LED)와 구동 회로로 구성되는 LED 교통 신호등은 특정 파장대의 단색광을 발광하므로, 기존의 백열전구식 신호등에 비해 시인성이 좋고, 80 % 이상의 에너지 절약이 가능하다. 그러나 LED는 주위 온도에 따라 밝기가 변화하는 특성이 있다. 신호등은 기능상 외부 온도의 영향 없이 항상 일정한 광도를 유지해야 하므로, 본 논문에서는 외부 온도의 변화에 관계없이 일정한 광출력을 유지할 수 있는 LED 구동회로를 설계한다 이를 위해 정전압 및 정전류로 구동되는 LED의 온도에 따른 광출력 특성 실험이 수행되고, 이러한 데이터들을 바탕으로 정광출력 LED 신호등 구동회로가 설계되고 그 성능을 평가한다.