• Journal of Digital Convergence
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• v.10 no.8
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• pp.179-184
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• 2012

A car accident on a highway occurs a chain-reaction collision because of a vehicle's fast velocity. In order to prevent it, the accident vehicle should broadcast a safe message to its neighbors. If there are many neighbor nodes, a frame collision probability is high. To solve this, it was proposed for a system as a previous study to send a safe message without frame-collision using separating channels. However, the separation of multiple channels make feasibility low because of increasing hardware's development cost and complexity. In this paper, we proposes a TDMA-based MAC protocol using a single channel. As a result, we show the frame reception success rate of our protocol was almost the same as the previous protocol.

• Journal of Korea Multimedia Society
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• v.15 no.10
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• pp.1221-1227
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• 2012

It is expected that the vehicle safety systems using vehicle-to-vehicle communication can reduce the possibility of vehicle collision and prevent the chain crash by promptly delivering the status of neighboring vehicles. Many IEEE 802.11 DCF based Flooding schemes have been proposed, but they may generally expose the problems that the transmission efficiency is sharply declined as the vehicle density has increased and then is related to the low possibility of the channel access. Therefore, this paper proposes a collision prevention scheme using adaptively controlling the frequency of the message exchanges based on the current status of neighboring vehicles. Moreover, it is shown from simulation that the proposed scheme provides the performance gains over the existing Flooding based scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.852-853
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• 2015

본 논문에서는 차량 추돌 방지 레이더용 24GHz 전압제어발진기를 제안한다. 제안한 회로는 TSMC $0.13-{\mu}m$ 고주파 CMOS 공정 ($f_T/f_{MAX}=120/140GHz$)으로 구현되어 있고, 1.5 볼트 전원전압에서 동작한다. 전체 칩 면적과 소비전력을 줄이기 위해 수동형 인덕터 대신 트랜지스터와 전류원으로 구성된 능동형 인덕터부를 사용하였다. 제작된 전압제어발진기는 기존 연구 결과에 비해 동작주파수에서 6.1mW의 낮은 소비전력 특성과 $0.06mm^2$의 매우 작은 칩 면적 특성을 보였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.780-781
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• 2014

본 논문에서는 차량 추돌 방지 단거리 레이더용 고 변환이득 및 저전력 24GHz CMOS 믹서를 제안한다. 이러한 회로는 2볼트 전원전압에서 동작하며, 저 전압 전원 공급에서도 높은 변환 이득과 낮은 잡음지수를 가지도록 설계되어 있다. 제안한 회로는 TSMC $0.13{\mu}m$ 혼성신호/고주파 CMOS 공정($f_T/f_{MAX}=120/140GHz$)으로 설계하였다. 전체 칩 면적을 줄이기 위해 실제 수동형 인덕터 대신 전송선을 이용하였다. 제안한 회로는 최근 발표된 연구결과에 비해 가장 높은 10.96dB의 변환이득, 7.6dBm의 IIP3를 보였고, 가장 적은 5mW의 소비전력 및 $0.2{\times}0.2m^2$의 칩 크기 특성을 보였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.6
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• pp.1125-1132
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• 2012

The researches on driver assistance systems that can prevent an accident have been actively performed due to social issues of traffic accidents with development of vehicle industry in recent. It is required for researchers to develope systems which assist driver's perception and judgment when considering that over 70% of traffic accidents occur by drivers' carelessness and 75% of the total accidents occur at the speed of less 29km per hour. In this paper, we implemented a front and rear vehicle monitoring system that monitors distance from a vehicle to obstacles in real-time at the low-speed or back-ward driving. The proposed system consists of ultrasonic sensors of high angle and wide angle of beam spread, ATmega128, and DSP processor.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.251-258
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• 2018

Recently, due to the increase in the traffic volume of vehicle, the collision of the vehicle collision has been increased so that the neck injuries of the passengers has been increased. In order to prevent this, vehicle collision analysis research using computer simulation has been actively carried out in consideration of the design point of car seat. In this study, I used the MADYMO program for analyzing the passenger behavior using a BioRID II dummy, and predicted the neck injuries of passengers according to the change of the backset at the rearward collision of the driving speed of 16km/h. As a result, it was found that the shorter the backset, the shorter the contact start time but the contact completion time was almost the same and the T1 acceleration showed that the acceleration increased with the backset. In addition, the tensile strength increases as the backset increases, and NIC (Neck Injury Criterion) increases as the head speed reaches the headrest.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.91-98
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• 2020

In order to prevent a collision accident during sudden braking, we have proposed an hazard lamps automatic operation system that can be easily installed in existing vehicles that do not have hazard lamps automatic operation. There are several ways to recognize sudden braking. Using GPS, the system does not work in a tunnel, and it is difficult to install the system additionally on an existing vehicle using a vehicle speed sensor. Therefore, the proposed system eliminates these problems by using the acceleration sensor and makes it possible to recognize even the sudden turning and bounce of the vehicle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.347-350
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• 2012

The researches on driver assistance systems that can prevent an accident have been actively performed due to social issues of traffic accidents with development of vehicle industry in recent. It is required for researchers to develope systems which assist driver's perception and judgment when considering that over 70% of traffic accidents occur by drivers' carelessness and 75% of the total accidents occur at the speed of less 29km per hour. In this paper, we implemented a front and rear vehicle monitoring system that monitors distance in real-time from a vehicle to obstacles at the low-speed or back-ward driving. The implemented system consists of a high angle ultrasonic sensor with distance detection of 10m and 10-degree angle, a wide angle ultrasonic sensor with the detection distance of 3m and a 180-degree, and a ATmega128 chip of ATmel company.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.47-54
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• 2021

The number of freeway traffic accidents in Korea is about 4,000 as of 2020, and deaths per traffic accident is about 3.7 times higher than other roads due to non-recurring congestion and high driving speed. Most of the accident types on freeways are side and rear-end collisions, and one of the main factors is hazard traffic flow caused by merge, diverge and accidents. Therefore, the hazard traffic flow, which appears in a continuous flow such as a freeway, can be said to be important information for the driver to prevent accidents. This study tried to classify hazard traffic flows, such as the speed change point and the section where the speed difference by lane, using individual vehicle information. The homogeneous segment of speed was classified using spatial separation based on geohash and space mean speed that can indicate the speed difference of individual vehicles within the same section and the speed deviation between vehicles. As a result, I could extract the diverging influence segment and the hazard traffic flow segment that can provide dangerous segments information of freeways.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.319-326
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• 2018

The safety interval to prevent collision between trains in a train control system is based on the braking distance according to the emergency braking of the train. The evaluation of the braking performance is based on the longitudinal train dynamics or the commissioning test in the test track, but since the conditions such as the weakening of the adhesion coefficient between the wheel and rail can not all be considered, these conventional methods are not sufficient to design of the train control systems. Therefore, in this study, the Monte Carlo Method (MCM) which can consider various environments is used to analyze braking performance and limitations. The braking model is based on the air braking used in the emergency braking and is modeled to take into account the braking pressure, efficiency, friction coefficient, adhesion condition, and vehicle mass distribution. It is confirmed that braking performance can be improved by controlling the quality of braking device. In addition, the change of the braking performance was confirmed according to the vehicle constituting the train. The results of this study are expected to be used as basic information for designing safety clearance for the train control systems and as a basis for improving the braking performance of railway vehicles.