• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.3
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• pp.595-601
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• 2015

These days, research related to Intelligent Transportation System (ITS) technology is being widely considered. ITS is inevitable for future transportation systems to reduce accidents, congestion, and offer a smooth flow of traffic. The use of Visible Light Communication (VLC) in ITS systems has been considered widely because of its EMC/EMI free and LED infrastructure reusable properties. Among the VLC schemes, this study analyzed the performance of the Color Shift Keying (CSK) scheme under a Vehicle-to-Infrastructure (V2I) downlink scenario to verify the capability of CSK as a communication tool for ITS. By modeling daylight noise using the modified Blackbody radiation model, this study examined the performance of V2I VLC under daytime conditions. The relationship between BER, the communication distance, and the amount of ambient-light noises under the pre-described V2I scenario were determined by simulations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.2
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• pp.138-145
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• 2007

Luminous traffic safety mark is restricted to use only the place that has a thick fog, many night traffic accidents, limited field of view due to structure of road. Recently, LEDs are used for luminous traffic safety mark, but we propose an organic LED for a novel luminous traffic safety mark in the near future. The device structure was $ITO/2-TNATA(500{\AA})/{\alpha}-NPD(200{\AA})/DPVBi(300{\AA})/BCP(10{\AA})/Alq_3(200{\AA})/LiF(10{\AA})/Al:Li(1000{\AA})$. The characteristics of the device are most efficient on occasion of using $N_2$ gas plasma treatment. Current density is $240.71mA/cm^2$ luminance $10,550cd/m^2$, and current efficiency 3.53cd/A at an applied voltage of 10V. The maximum EL wavelength of the fabricated blue organic light-emitting device is 456nm. CIE color coordinates are x=0.1449 and y=0.1633, which is similar to NTSC deep-blue color with CIE color coordinates of x=0.14 and y=0.08.

• Current Optics and Photonics
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• v.1 no.3
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• pp.207-213
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• 2017

The Adaptive Front-lighting System (AFS) is a part of the active safety system, providing optimized vision to the driver during night time and other poor-sight conditions of the road by automatic adaptation of lighting to environmental and traffic conditions. Basically, an AFS provides four different modes of the passing beam as designated in an United Nations Economic Commission for Europe regulation (ECE324-R123): neutral state or country light (Class C), urban light (Class V), highway light (Class E), and adverse weather light (Class W). In this paper, we first present an optics design for an AFS system capable of producing the Class C/V/E/W patterns requiring only on/off modulation of multi-array LEDs with no need for any additional mechanical components. The AFS optics consists of two separated modules, cutoff and spread; the cutoff module lights a narrow central area with high luminous intensity, satisfying the cutoff regulation, and the spread module forms a wide spread beam of low luminous intensity. Each module consists of two major parts; the first converts a discretely positioned LED array into a full-filled area emitting light source plane, and the second projects the light source plane to a 25 m away target plane. With the combination of these two optics modules, the four beam patterns are formed by simple on/off modulation of multi-array LEDs. Then we report the development of a prototype that was demonstrated to provide the four beam patterns.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.01a
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• pp.163-164
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• 2020

교통 신호등 자동 제어시스템 기술은 교통 체증 현상을 방지하고 횡단 보도를 건너는 보행자들의 안전을 목적으로 시작되었다. 이는 1가구당 2차량에 가까운 보급률을 보이고 있는 현대 사회에 불가피하게 생기는 문제인데 본 연구에서는 이러한 문제로 인한 교통 신호등 자동 제어시스템 기술을 적용하고자 한다. 사거리에서 운전을 하다 보면 차량이 많이 지나가는 차선이 있는 반면 비교적 차량이 많이 지나가지 않는 차선들을 볼 수 있다. 이런 경우 차량이 많은 차선은 신호시간 내 차량이 모두 지나가지 못해서 교통체증이 발생하게 된다. 교통 체증을 최소화하기 위해서 압력 센서를 설치하여 차량이 많이 정체 되고 있는 차선에 신호의 시간을 증가시켜주고 차량이 많이 없는 차선은 기본 신호의 시간을 주어 차량이 많이 있는 차선의 차들의 교통 체증을 해소시켜 준다. 그리고 차량이 많이 지고 스마트폰의 보급이 많아지다 보니 횡단 보도에서 스마트폰을 보고있다 횡단 보도에서 사고를 당하는 경우 증가하고 있다. 이러한 보행자들을 위해 횡단 보도의 신호가 초록불이 되었을 때 간단한 음악이 나오고 발 밑에 횡단 보도 신호등과 같은 색깔이 나오게 하는 LED를 설치한다. 이렇게 하여 초록불이 들어왔다는 것을 보행자들에 인식시켜 보행자들의 안전을 지킬 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.169-170
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• 2021

기존 신호등은 보행자를 위한 별도의 안전장치가 없다. 이는 어린아이는 물론 성인들까지 차량의 위협으로부터 안전을 보장받을 수 없다. 본 연구에서는 어린이보호구역에서 사고 발생률을 감소시키는 것을 전제로 아두이노 액추에이터와 스위치를 이용한 전자제어 신호등을 적용하고자 한다. 현재의 신호등 시스템은 단순히 시간의 흐름에 따라 보행자 신호등과 차량용 신호등의 led가 자동으로 변화하여 차량과 보행자를 통제한다. 이러한 시스템은 어린아이들의 돌발행동과 운전자의 미숙한 작동으로 인한 사고를 방지하지 못한다. 본 논문은 이러한 문제점들을 개선하기 위해 기존의 신호등 시스템 대신 스위치와 액추에이터, 초음파 센서, 블루투스 모듈을 적용한 어린이용 보호 전자제어 신호등 기술을 제안한다. 기존의 신호등 시스템과는 다르게 보행자의 직접적인 개입을 통해 시스템을 제어하고, 원활한 교통환경을 만들 수 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.312-312
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• 2013

GaN based light emitting diodes (LEDs) are important devices that are being used extensively in our daily life. For example, these devices are used in traffic light lamps, outdoor full-color displays and backlight of liquid crystal display panels. To realize high-brightness GaN based LEDs for solid-state lighting applications, the development of p-type ohmic electrodes that have low contact resistivity, high optical transmittance and high refractive index is essential. To this effect, indiumtin oxide (ITO) have been investigated for LEDs. Among the transparent electrodes for LEDs, ITO has been one of the promising electrodes on p-GaN layers owing to its excellent properties in optical, electrical conductivity, substrate adhesion, hardness, and chemical inertness. Sputtering and e-beam evaporation techniques are the most commonly used deposition methods. Commonly, ITO films on p-GaN by sputtering have better transmittance and resistivity than ITO films on p-GaN by e-bam evaporation. However, ITO films on p-GaN by sputtering have higher specific contact resistance, it has been demonstrated that this is due to possible plasma damage on the p-GaN in the sputtering process. In this paper, we have investigated the advanced sputtering using plasma damage-free p-electrode. Prepared the ITO films on the GaN based LEDs by e-beam evaporation, normal sputtering and advanced sputtering. The ITO films on GaN based LEDs by sputtering showed better transmittance and sheets resistance than ITO films on the GaN based LEDs by e-beam evaporation. Finally, fabricated of GaN based LEDs by using advanced sputtering. And compared the electrical properties (measurement by using C-TLM) and structural properties (HR-TEM and FE-SEM) of ITO films on GaN based LEDs produced by e-beam evaporation, normal sputtering and advanced sputtering. As a result, It is expected to form plasma damage free-electrode, and better light output power and break down voltage than LEDs by e-beam evaporation and normal sputter.

• Environmental Engineering Research
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• v.24 no.1
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• pp.159-172
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• 2019

To investigate the influence of pollution events on the chemical composition and formation processes of aerosol particles, 24-h integrated size-segregated particulate matter (PM) was collected during the fall season at an urban site of Gwangju, Korea and was used to determine the concentrations of mass, water-soluble organic carbon (WSOC) and ionic species. Furthermore, black carbon (BC) concentrations were observed with an aethalometer. The entire sampling period was classified into four periods, i.e., typical, pollution event I, pollution event II, and an Asian dust event. Stable meteorological conditions (e.g., low wind speed, high surface pressure, and high relative humidity) observed during the two pollution events led to accumulation of aerosol particles and increased formation of secondary organic and inorganic aerosol species, thus causing $PM_{2.5}$ increase. Furthermore, these stable conditions resulted in the predominant condensation or droplet mode size distributions of PM, WSOC, $NO_3{^-}$, and $SO{_4}^{2-}$. However, difference in the accumulation mode size distributions of secondary water-soluble species between pollution events I and II could be attributed to the difference in transport pathways of air masses from high-pollution regions and the formation processes for the secondary chemical species. The average absorption ${\AA}ngstr{\ddot{o}}m$ exponent ($AAE_{370-950}$) for 370-950 nm wavelengths > 1.0 indicates that the BC particles from traffic emissions were likely mixed with light absorbing brown carbon (BrC) from biomass burning (BB) emissions. It was found that light absorption by BrC in the near UV range was affected by both secondary organic aerosol and BB emissions. Overall, the pollution events observed during fall at the study site can be due to the synergy of unfavorable meteorological conditions, enhanced secondary formation, local emissions, and long-range transportation of air masses from upwind polluted areas.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.1
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• pp.31-37
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• 2024

In this study, we propose a machine vision-based pedestrian signal detection algorithm that operates efficiently even in computing resource-constrained environments. This algorithm demonstrates high efficiency within limited resources and is designed to minimize the impact of ambient lighting by sequentially applying HSV color space-based image processing, binarization, morphological operations, labeling, and other steps to address issues such as light glare. Particularly, this algorithm is structured in a relatively simple form to ensure smooth operation within embedded system environments, considering the limitations of computing resources. Consequently, it possesses a structure that operates reliably even in environments with low computing resources. Moreover, the proposed pedestrian signal system not only includes pedestrian signal detection capabilities but also incorporates IoT functionality, allowing wireless integration with a web server. This integration enables users to conveniently monitor and control the status of the signal system through the web server. Additionally, successful implementation has been achieved for effectively controlling 50W LED pedestrian signals. This proposed system aims to provide a rapid and efficient pedestrian signal detection and control system within resource-constrained environments, contemplating its potential applicability in real-world road scenarios. Anticipated contributions include fostering the establishment of safer and more intelligent traffic systems.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.11a
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• pp.851-853
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• 2022

고령화로 인해 65세 이상 운전자가 급증하며 고령운전자의 교통사고 비율이 증가함에 따라 시급한 사회 문제로 떠오르고 있다. 이에 본 연구에서는 객체 검출, 인식 모델을 결합하고 신호등을 인식하여 Text-To-Speech(TTS)로 알리는 쿠버네티스 기반의 프레임워크를 제안한다. 객체 검출 단계에서는 YOLOv5 모델들의 성능을 비교하여 활용하였으며 객체 인식 단계에서는 C-RNN 기반의 attention-OCR 모델을 활용하였다. 이는 신호등의 내부 LED 영역이 아닌 이미지 전체를 인식하는 방식으로 오탐지 요소를 낮춰 인식률을 높였다. 결과적으로 1,628장의 테스트 데이터에서 accuracy 0.997, F1-score 0.991의 성능 평가를 얻어 제안한 프레임워크의 타당성을 입증하였다. 본 연구는 후속 연구에서 특정 도메인에 딥러닝 모델을 한정하지 않고 다양한 분야의 모델을 접목할 수 있도록 하며 고령 운전자 및 신호 위반으로 인한 교통사고 문제를 예방할 수 있다.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.114-124
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• 2019

The drone market, an unmanned aerial vehicle, is rapidly expanding and developing into an important area related to the huge changes in the traffic system of the future. With various technologies on the fourth industrial revolution, including drones, mentioned at the Davos Forum in January 2016, interest in drones is emerging as an explosive demand for national certificates. The number of drone pilots, which was only 400 in 2015, is continuing to surpass 17,000 as of 2018. Therefore, this study analyzed the safety perception of the pilots based on the DREEM (Dundee ready environmental assessment) model designed to evaluate the educational environment along with the current state of drone education in Korea. This led to the conclusion that the high level of satisfaction of the pilot with the educational environment contributes to the overall safety perception, including compliance with procedures.