• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.603-605
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• 2021

With the expansion of the indoor service-providing robot market and the electrification of automobiles, research on autonomous driving is being actively conducted. In general, in the case of outside, the location is mainly recognized through GPS, and location positioning is performed indoors using technologies such as WiFi, UWB (Ultra-Wide Band), VLP, LiDAR, and Vision. In this paper, we introduce a system for location-positioning using LED lights with different color temperatures in an indoor environment. After installing LED lights in a simulated environment such as a tunnel, it was shown that information about the current location can be obtained through the analysis of chromaticity values according to location. Through this, it is expected to be able to obtain information about the location of the vehicle in the tunnel and the movement of the device in a room such as a warehouse or a factory.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.177-179
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• 2013

This paper presents an LED driver which requires a high voltage gain (5-6 times). To achieve a high voltage gain, the tapped-inductor boost converter topology was used and through the analysis of converter's steady-state and its dynamic characteristics, the product design's reliability and validity were verified.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.218-220
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• 2008

This paper describes buck converter's MOSFET driver for high-brightness LED strings. The power driving high-side MOSFET is supplied from the power source of control circuit part. The practical considerations and future work are also described.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.49-49
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• 2009

Phosphors with oxide host material, YAG:$Ce^{3+}$ and $(Ca,Sr,Ba)_2SiO_4:Eu^{2+}$ yellow phosphor, has been used for LED applications. The WLEDs using these phosphors are widely used for LCD backlighting, automobile, and general lighting applications since they have high conversion efficiency and good thermal and chemical stability which can meet necessary life time of LED products up to now. With advances of LED chip technology, the external quantum efficiency and driving current in chip get higher so that the phosphors for high power chip are required to maintain high conversion efficiency and stability at high temperature due to the heat dissipated from LED chips. In addition, higher color rendering index of LED lighting and color reproducibility of LCD than those of LEDs with single yellow phosphors are required. In order to overcome these technical issues rising from evolution of LED technology, new phosphors are in demand and nitride phosphors, one of the promising new candidate materials, will be discussed here.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.171-173
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• 2009

최근 LED 기술의 발달로 LED의 이용범위가 점차 넓어지고 있다. 이러한 LED를 구동하기 위한 시스템의 저비용 고효율을 위해서는 입력전압에 대한 출력전압의 승강압이 중요하다. 따라서 본 논문에서는 승강압이 가능한 DC-DC 컨버터인 Buck-Boost, ZETA, SEPIC 토폴로지를 적용하여 LED Lamp 구동 시스템을 구성해 본다. 위 세 가지의 컨버터는 입력전압에 대하여 출력전압의 승강압이 가능하고 입출력 전압특성이 동일하다. 그러므로 각각의 컨버터들을 이용하여 LED driving 회로를 구성하고, Pspice 시뮬레이션을 통해 나타나는 입출력 효율을 측정하여 승강압용 DC-DC 컨버터의 특성을 비교한다.

• Journal of the Ergonomics Society of Korea
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• v.28 no.2
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• pp.9-16
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• 2009

The aim of this study was to evaluate the effects of the driving performance and workload according to changing driving environment and types of steering wheel. Twelve drivers who participated in this study consisted of two groups; six Japanese as the left-lane drivers who was accustomed to driving on left-hand side of the road, and six Europeans, Americans, and Korean as the right-lane drivers who was accustomed to driving on right-hand side of the road. They were asked to operate a driving simulator while using two different types of steering wheel (for the left-hand side driving and the right-hand side driving). During the experiment, a range of data were measured including driving performance, mental workload, and eye movements which were recorded in order to identify the amount of time looking towards the in-vehicle route guidance. Results indicated that the use of the steering wheel by parallel moving led to increase high attentional demand and worse glance behavior to traffic signs for the left-lane drivers. In the case of the right-lane drivers, the effects by changing driving direction were more effective than the types of steering wheel due to their habit or traits.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.1-7
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• 2020

In recent years, as LED display systems are actively spread, study on effective control methods for an LED driver for driving the systems has been in progress. The most representative among them is the uniform brightness control method for the LED driver channel. In this paper, we propose an LED driver IC for BLU with current compensation and system protection functions to minimize channel luminance deviation. It is designed for current accuracy within ±3% between channels and a channel current of 150 mA. In order to satisfy the design specifications, the channel amplifier offset was canceled out by a chopping operation using a channel-driving PWM signal. Also, a pre-charge function was implemented to minimize the fast operation speed and luminance deviation between channels. LED error (open, short), switch TR short detection, and operating temperature protection circuits were designed to protect the IC and BLU systems. The proposed IC was fabricated using a Magnachip 0.35-um CMOS process and verified using Cadence and Synopsys' Design Tool. The fabricated LED driver IC has current accuracy within ±1.5% between channels and 150-mA channel output characteristics. The error detection circuits were verified by a test board.

• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.247-252
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• 2013

An intelligent light emitting diode (LED) dimming system is designed and implemented for energy-saving lighting systems. An LED light bulb is powered by an LED driver controlled by a microcontroller using pulse width modulation (PWM) signals. By changing the duty cycle of the PWM signals, the LED driver generates a driving current of up to 1,000 mA. The current consumption by the LED light bulb exhibits a very linear characteristic that indicates that the level of LED dimming can be finely tuned. Multiple sensors-lighting intensity and ultrasonic range sensors-are combined with the LED dimming system to realize an automatically controllable LED lighting system. The light intensity sensor is capable of sensing ambient light. The ultrasonic range sensor can detect objects from 0.15 to 5.6 m at a resolution of 0.0254 m. The collected information by the light intensity and ultrasonic range sensors is processed by the microcontroller that in turn automatically controls the brightness of the LED light bulb. The algorithm of the software for the LED dimming system is also described.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1726-1727
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• 2011

본 연구는 RGB LED 패키지의 특성에 대한 전기적 분석을 통해 LED 조명 설계에 있어 보다 효율적인 설계를 구현하고자 하였으며 마이크로 컨트롤러를 이용한 구동회로 제어와 적외선 센서를 이용한 원격제어를 통해 폭넓은 색 조절을 위한 LED에 최적화 된 brightness 및 chroma 제어 기술을 실현하고자 설계 및 분석을 하였다. 그 결과 색온도에 대한 제어의 경우 총 12가지의 mode를 바탕으로 색상을 제어 하였으며 LED 패키지의 전류변화에 따른 광 출력을 고려하여 최적화 된 brightness 및 색온도에 대한 제어가 가능하였다.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.546-547
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• 2010

최근 고출력 LED의 기술적 진보에 따라 여러 분야에서 LED의 적용 시도가 확산되고 있다. 그 중 LED 무대조명은 조도 제어범위가 넓어 매우 낮은 전력에서 LED를 정전류로 구동할 필요가 있다. 본 논문에서는 200Watt급 RGBW Moving Light를 매우 낮은 전력까지 구동하기 위하여 DC 전류제어 디밍 방식을 적용하였으며, 이를 위한 회로를 설계하여 이를 실험적으로 검증하였다.