• 한국대기환경학회지
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• 제28권4호
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• pp.396-410
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• 2012

The purpose of this study is to quantify the contribution of high emitting vehicles to mobile emission inventories. Analyzed emission data include $NO_x$, HC, and CO results, which were measured through the vehicle Inspection and Maintenance (I/M) program in Seoul metropolitan area. The high emitting vehicles were identified as the top 5% worst polluting cars of the fleet. We estimated that 5% of the gasoline passenger car fleet, which is high emitters, generated 25.5% of $NO_x$, 34.5% of HC, and 66.1% of CO emissions of total inventories for gasoline passenger car fleet in year 2010. In the study, we identified that the older vehicles (older than ten years) and high mileage vehicles (more than 120,000 km driven) comprised high emitter fleet with 70.9% and 71.2%, respectively. The emission contribution of high emitters became larger in younger fleet than in the older fleet. This is due to the reduced emission rates in newly manufactured vehicles, which were developed under the more stringent emission regulation limits. This analysis implies that high emitters could be responsible for an even larger fraction of total vehicular emissions as more advanced technology vehicles are being incorporated into the current vehicle fleet. The findings suggested that the high emitting vehicles should be primarily considered for in-use vehicle emission management program, such as I/M, accelerated vehicle retirement, or catalytic converter replacement, in order to enhance the effectiveness of selected program.

• 한국대기환경학회지
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• 제29권6호
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• pp.745-756
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• 2013

The purpose of this study is to evaluate representativeness of fuel-based emission factors. Twelve light-duty diesel vehicles which meet Euro-3 to 5 legislative emission limits were selected for emission tests. Second-by-second modal emission rates of vehicles were measured on a standard laboratory chassis dynamometer system. An off-cycle driving cycle was developed as a representative Korean real-world on-road driving cycle. Fuel-based emission factors were developed for short trip segments that involved in the selected driving cycle. Each segment was defined to have unit travel distance, which is 1 km, and characterized by its average speed and Relative Positive Acceleration (RPA). Fuel-based $NO_x$ emission factors demonstrate relatively good representativeness in terms of vehicle operation conditions. $NO_x$ emission factors are estimated to be within ${\pm}20%$ of area-wide emission factor under more than 40% of total driving situations. This result implies that the fuel-based $NO_x$ emission factor could be practically implemented into the on-road emission management strategies, such as a remote sensing device (RSD). High emitting vehicles as well as high emitting operating conditions heavily affect on the mean values and distributions of CO and THC emission factors. Few high emitting conditions are pulling up the mean value and biasing the distributions, which weaken representativeness of fuel-based CO and THC emission factors.

• Current Optics and Photonics
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• 제1권6호
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• pp.613-617
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• 2017

Due to optimal advances such as chromatic performance, durability, low power consumption, high efficiency, long-lifetime, and excellent environmental friendliness, white LEDs (WLEDs) are widely used in vehicle front lighting, backlighting, decorative lighting, street lighting, and even general lighting. In this paper, the remote packaging WLEDs (RP-WLEDs) with bi-layer red-emitting $Sr_2Si_5N_8:Eu^{2+}$ and yellow-emitting YAG:Ce phosphor was proposed and investigated. The simulation results based on the MATLAB software and the commercial software Light Tools indicated that the color rendering index (CRI) of bi-layer phosphor RP-WLEDs had a significant increase. The CRI had a considerable increase from 72 to 94. In conclusion, the results showed that bi-layer red-emitting $Sr_2Si_5N_8:Eu^{2+}$ and yellow-emitting YAG:Ce phosphor could be a prospective approach for manufacturing RP-WLEDs with enhanced optical properties.

• 한국군사과학기술학회지
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• 제25권4호
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• pp.355-363
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• 2022

Development of supersonic flying vehicle is one of the most latest issue in modern military technology. Specifically, structural integrity of supersonic flying vehicle can be verified by high temperature structural test. High temperature structural test is required to consider thermal load caused by aerodynamic heating while applying structural load simultaneously. Tubular quartz lamps are generally used to generate thermal load by emitting infrared radiation. In this study, modified heat flux model of tubular quartz lamp is proposed based on existing model. Parameters of the proposed model are optimized upon measured heat flux in three dimensions. Finally, thermal load of plate specimen is designed by the heat flux model. In conclusion, it is possible to predict heat flux applied on plate specimen and desired thermal load of high temperature structural test can be obtained.

• Journal of Multimedia Information System
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• 제5권2호
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• pp.105-110
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• 2018

Autonomous cars require the integration of multiple communication systems for driving safety. Many carmakers unveil mirrorless concept cars aiming to replace rear and sideview mirrors in vehicles with camera monitoring systems, which eliminate blind spots and reduce risk. This paper presents optical vehicle-to-vehicle (V2V) communications for autonomous mirrorless cars. The flicker-free light emitting diode (LED) light sources, providing illumination and data transmission simultaneously, and a high speed camera are used as transmitters and a receiver in the OCC link, respectively. The rear side vehicle transmits both future action data and vehicle type data using a headlamp or daytime running light, and the front vehicle can receive OCC data from the camera that replaces side mirrors so as not to prevent accidents while driving. Experimental results showed that action and vehicle type information were sent by LED light sources successfully to the front vehicle's camera via the OCC link and proved that OCC-based V2V communications for mirrorless cars can be a viable solution to improve driving safety.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.476-481
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• 2009

In this paper, we propose a visible light road-to-vehicle communication system at intersection as one of ITS technique. In this system, the communication between vehicle and a LED traffic light is approached using LED traffic light as the transmitter, and on-vehicle high-speed camera as the receiver. The LEDs in the transmitter are emitted with 500Hz and those emitting LEDs are captured by a high-speed camera for making communication. The images from the high-speed camera are processed to get luminance value of each LED in the transmitter. For this purpose, first transmitter should be found, then it should be tracked for each frame, and the luminance value of each LED in the transmitter should be captured. In our previous work, transmitter was found by getting the subtraction of two consecutive frames. In this paper, we mainly introduce an algorithm to detect the found transmitter in consecutive frames. Experimental results using appropriate images showed the effectiveness of the proposal

• 방송공학회논문지
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• 제14권4호
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• pp.475-487
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• 2009

We propose a visible light road-to-vehicle communication system at intersection as one of ITS technique. In this system, the communication between vehicle and a LED traffic light is approached using LED traffic light as a transmitter, and on-vehicle high-speed camera as a receiver. The LEDs in the transmitter are emitted in 500Hz and those emitting LEDs are captured by a high-speed camera for making communication. Here, the luminance value of each LED in the transmitter should be found for consecutive frames to achieve effective communication. For this purpose, first the transmitter should be identified, then it should be tracked for consecutive frames while the vehicle is moving, by processing the images from the high-speed camera. In our previous work, the transmitter was identified by getting the subtraction of two consecutive frames. In this paper, we mainly introduce an algorithm to track the identified transmitter in consecutive frames. Experimental results using appropriate images showed the effectiveness of the proposal.

• 에너지공학
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• 제28권4호
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• pp.35-41
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• 2019

기존에 차량용 안개등으로 사용되었던 할로겐 광원은 전력소모가 증가하고 수명이 짧기 때문에 이러한 단점을 극복하기 위해 자동차 광원은 LED로 점차 바뀌고 있다. 그러나 차량용 LED 안개등을 점등하였을 경우에는 LED에서 발생하는 고열로 인해 안개등 수명을 단축시키는 단점이 있다. 안개등 내부에서 LED에 의해 발생된 열은 주로 히트싱크에 의해 배출되지만, 나머지 열은 거의 대부분 대류를 통해 외부로 배출된다. 이러한 대류에 의한 냉각효율이 저하되면 열에너지는 램프의 주요부품인 렌즈, 리플렉터, 베젤 등에 열을 발생시키거나 LED 광원에 고온을 발생시켜 LED 안개등의 수명을 단축시킨다. 따라서, 본 연구에서는 히트싱크에 의한 방열방식 이외에도 냉각효율에 중요한 영향이 미치는 대류에 의한 방열성능을 개선하고자 하였다. 이를 위해 차량용 LED 안개등 내부공기를 외부로 흡·배출시킬수 있는 통풍구 설치 위치를 결정하기 위한 열유동해석을 수행하여 최적의 설계가 되도록 하였다. 공기의 평균속도는 기존 프로토타입인 Case1에 비해 Case3, Case2의 순으로 증가되었고 Case3의 증가폭이 다른 Case에 비해 상대적으로 큰 것을 알 수 있었다. 이는 안개등 상·하에 설치된 통풍구가 온도차이에 따라 생성되는 대류현상을 적절하게 유도하기 때문에 공기의 속도 증가와 함께 열을 효율적으로 배출시켰기 때문인 것으로 판단하였다.

• 방송공학회논문지
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• 제20권6호
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• pp.928-937
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• 2015

기존의 헤드업 디스플레이는 작은 허상 크기로 인하여 운전자가 영상 정보를 쉽게 인식할 수 없는 어려움을 가지고 있기 때문에, 본 연구에서는 수평 방향으로 영상을 넓히는 다중 화면 구조와 컴바이너 렌즈를 사용하여 영상 확대와 다채널 윈도우 구조의 헤드업 디스플레이를 연구하였다. 0.47inch 크기의 LCD를 사용하여 투과와 반사 기능의 허상 영상을 사람의 눈에서 3m 위치에 구현하는 기술을 연구하여 근거리와 원거리의 물체에 대한 운전자의 인지 시간을 짧게 하였다. 허상 영상의 콘텐츠로는 스마트 폰을 이용하여 다양한 내비게이션 정보 등을 디스플레이 할 수 있도록 하여 안전과 정보를 동시에 제공할 수 있도록 하였다.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.23-30
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• 2014

"Cut off line" in automotive passing beam has very important safety function because it serves for headlamp aiming. Headlights that are aimed incorrectly will not only perform poorly but also offend oncoming traffic. In addition, an objective definition of cut off line in low beam is necessary, since a requirement for correct aiming of the beams is specified within all the existing regulations. Accordingly, headlight regulations are requirements that automobiles must satisfy in order to be sold in a particular country. In this study, a more advanced recognition method for the cut off lines of the various headlamps commonly used in Europe, North America, and domestic is suggested and a headlamp testing system is developed to adjust the beam to the country-specific regulation. This system uses image processing technology to detect the cut off lines in the beam patterns of halogen headlamps, high-intensity discharge headlamps, and light-emitting diode headlamps as well.