• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.1
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• pp.105-122
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• 2011

The fundamental design goal of wireless sensor MAC protocols is to minimize unnecessary power consumption of the sensor nodes, because of its stringent resource constraints and ultra-power limitation. In existing MAC protocols in wireless sensor networks (WSNs), duty cycling, in which each node periodically cycles between the active and sleep states, has been introduced to reduce unnecessary energy consumption. Existing MAC schemes, however, use a fixed duty cycling regardless of multi-hop communication and traffic fluctuations. On the other hand, there is a tradeoff between energy efficiency and delay caused by duty cycling mechanism in multi-hop communication and existing MAC approaches only tend to improve energy efficiency with sacrificing data delivery delay. In this paper, we propose two different MAC schemes (ADS-MAC and ELA-MAC) using closed-loop control in order to achieve both energy savings and minimal delay in wireless sensor networks. The two proposed MAC schemes, which are synchronous and asynchronous approaches, respectively, utilize an adaptive timer and a successive preload frame with closed-loop control for adaptive duty cycling. As a result, the analysis and the simulation results show that our schemes outperform existing schemes in terms of energy efficiency and delivery delay.

• Journal of Auto-vehicle Safety Association
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• v.11 no.4
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• pp.28-38
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• 2019

In the world, traffic accidents and environmental pollution caused by the increase of vehicles are becoming a serious social problem. According to the 2016 data published by the Korea Highway Traffic Authority, Korea owns 49.9 vehicles per 100 people. This is the 28th largest number among the 35 OECD member countries. In addition, the number of deaths from traffic accidents in Korea totaled 4,292, of which 1,714 were caused by traffic accidents involving vehicles and pedestrians. To reduce these human casualties, the automotive industry is constantly working on the development and commercialization of Adaptive Driver Assist System (ADAS). ADAS is the system providing convenience and safeness for drivers. In general, ADAS consists of Autonomous Emergency Braking (AEB), Highway Driving Assist (HDA), Adaptive Cruise Control (ACC), Lane Keeping Assist System (LKAS). Among them, the AEB detects the possibility of collision by the vehicle itself and plays a role of avoiding the collision or reducing the damage through active braking. For such AEB, Euro NCAP has been developing test-evaluation methods for the vulnerable since 2017. Therefore, In this paper analyzes the scenario of Euro NCAP VRU Test Protocol v3.0.1, which will be established in 2020, and proposes test conditions according to the Korean road traffic law. In addition, the reliability of the proposed scenario and test conditions was verified by comparing and analyzing the proposed theoretical evaluation formulas and actual test results.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1493-1496
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• 2011

Research results for LMS-based algorithms performances using real records of the traffic noise are discussed. The various algorithms based on LMS method are studied regarding their convergence speed and noise reduction index. Most effective algorithms are chosen for implementation in the active noise control barriers. The optimal step size, and number of adaptive filter taps are addressed during parametric study of the algorithms.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2962-2964
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• 1999

We know the traffic information about the velocity and position of vehicle by extraction and tracking vehicle from continuosly obtained road image of camera. The conventional method of vehicle detection indicate increment of error due to headlight and taillight in night road image. This paper show such as vehicle detection of binary, Edge detection. amalgamation of image are applied to extract the vehicle, and Kalman filter is adaptive methods for tracking position and velocity of vehicle.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1501-1506
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• 1999

DSRC(Dedicated Short Range Communications), which is a radio mobile communication protocol in ITS, is suited for traffic related information services. But in WAC(Wide-Area wireless communications), we could consider a conventional communication infrastructure in the case of supporting other applications besides ITS. Especially considering the current the trends to introduce wireless internet service into the mobile communication network, wireless internet service in ITS system is valuable. Although ITS LLC(Logical Link Control) protocols recommended by Europe and Japan are effective for traffic related services, it is not suitable for services related with geographical information, image or internet. That is because the data traffic characteristics is changed according to service types. Therefore we suggest a logical link control algorithm effective for traffic information related services as well as internet web service, and analyze its performance. As a result of numerical analysis and simulation, proposed algorithm shows larger performance improvements. For traffic information related services, the performance of DSRC LLC recommended by Europe and Japan is the same as that of proposed LLC protocol. However, for wireless internet web service, the performance of proposed protocol is much better than that of LLC protocol used in Europe and Japan.

• Journal of Internet Computing and Services
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• v.21 no.6
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• pp.1-12
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• 2020

Low-Orbit satellite mobile networks can provide services through miniaturized terminals with low transmission power, which can be used as reliable means of communication in the national public disaster network and defense sector. However, the high traffic environment in the emergency preparedness situation increases the new call blocking probability and the handover failure probability of the satellite network, and the increase of the handover failure probability affects the QoS because low orbit satellites move in orbit at a very high speed. Among the channel allocation methods of satellite communication, the FCA shows relatively better performance in a high traffic environment than DCA and is suitable for emergency preparedness situations, but in order to optimize QoS when traffic increases, the new call blocking and the handover failure must be minimized. In this paper, we propose LEO-DBC (LEO satellite dynamic beam width control) technique, which improves QoS by adaptive adjustment of beam width of low-orbit satellites and call time of terminals by improving FCA-QH method. Through the LEO-DBC technique, it is expected that the QoS of the mobile satellite communication network can be optimally maintained in high traffic environments in emergency preparedness situations.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.11
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• pp.962-966
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• 2001

The major problem at a branch point for point-to-multipoint available bit rate(ABR) services in asynchronous transfer mode (ATM) networks is how to consolidate backward resource management(BRM) cells from each branch for a multicast connection. In this paper, we propose an efficient feedback consolidation algorithm based on an adaptive dynamic threshold(ADT) to eliminate the consolidation noise and the reduce the consolidation delay. The main idea of the ADT algorithm lies in that each branch point estimates the ABR traffic condition of the network through the virtual queue estimation and the transmission threshold of the queue level in branch points is adaptively controlled according to the estimation. Simulation results show that the proposed ADT algorithm can achieve a faster response in congestion status and a higher link utilization compared with the previous works.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.159-164
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• 2007

The Advanced Safety Vehicle (ASV) allows drivers not only convenience and safety, but also many useful services provided by the Telematics technology. Since ASV is expected to be widely used in the near future, it is necessary to ensure the safety of ASV systems. Among several aspects of ASV, this paper investigates the safety of the Adaptive Cruise Control (ACC) system. Field tests are carried out under the domestic roadway and traffic conditions, according to International Standard Organization (ISO) requirements for ACC. The test data are analyzed whether the requirements are adequate for domestic circumstances, and the suggestions for findings are given.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.473-482
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• 2015

Recent development in science and technology has enabled vehicles to be equipped with advanced autonomous functions. ADAS (Advanced Driver Assistance Systems) are examples of such advanced autonomous systems added. Advanced systems have several operational modes and it has been observed that drivers could be unaware of the mode they are in during vehicle operation, which can be a contributing factor of traffic accidents. In this study, possible mode confusions in a simulated environment when vehicles are equipped with an adaptive cruise control system were investigated. The mental model of the system was designed and verified using the formal analysis method. Then, the user interface was designed on the basis of those of the current cruise control systems. A set of human-in-loop experiments was conducted to observe possible mode confusions and redesign the user interface to reduce them. In conclusion, the clarity and transparency of the user interface was proved to be as important as the correctness and compactness of the mental model when reducing mode confusions.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.343-345
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• 2012

기존의 교통제어 시스템은 고정된 녹색 신호의 길이와 주기를 갖고 있다. 그에 따라 차선 간 차량 밀집도가 불균형한 경우 교통 처리량이 저하되고 응급상황이 발생할 경우 지정체가 유발된다. 본 논문에서는 VANET을 이용하여 교통량의 실시간 정보를 수집해 적응적으로 교통 신호를 제어하는 시스템을 제안한다. 차량의 수, 평균 신호대기 시간, 차선 간 균형, 응급상황 등을 고려하여 교통 신호를 가변적으로 제어 한다. 차량이 교차로에 진입하기 전 통신모듈을 갖고 있는 신호등에게 위치, 방향, 속도 정보 등을 송신하고 traffic control system에서 교통량을 분석하여 녹색 신호를 가변적으로 할당 한다. 실험결과 제안 기법이 교통 처리량, 평균 신호대기시간에서 기존 교통신호 제어 기법보다 높은 성능을 확일 할 수 있었다.