• 대한토목학회논문집
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• 제35권4호
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• pp.897-905
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• 2015

본 연구에서는 충격파 모형을 이용하여 능동식 우선신호의 최적 신호시간을 산정하기 위한 모형을 제시하였다. 본 신호 최적화 모형을 이용하여 능동형 우선신호 기법 중 Early green 및 Green extension이 적용되는 조건에서 충격파 면적을 산정할 수 있다. 본 연구에서는 평균통행시간 및 교차로 진출시각을 이용해 충격파의 발생 속도를 산정하기 위한 방법을 제시하였으며, 이를 이용해 우선신호로 인한 현시 변화량에 따라 충격파 면적 변화량을 산정할 수 있다. 또한 교차로 전체의 충격파 면적이 최소화되는 신호시간을 산정하여 우선신호로 인해 증가하는 일반차량의 지체를 최소화할 수 있도록 하였다. 우선신호 신호시간 산정 모형의 효과평가를 위해 VISSIM과 ComInterface를 이용한 미시적 시뮬레이션 분석을 시행하였으며, 이동류의 포화상태를 고려하여 지체 최소화를 위한 신호시간이 산정됨을 확인하였다. 독립교차로를 대상으로 하는 사례분석에서 우선신호를 위해 비우선현시를 균일하게 단축하는 전략 대비 본 모형에서 일반차량 지체가 10% 이상 개선됨을 확인하였다. 본 연구는 트램, BRT, 중앙버스 전용차로 등 대중교통 우선시설이 확산되고 있는 최근 국내 상황에서 신호교차로의 운영효율을 높이기 위한 새로운 우선신호 제어 방법을 제시하였다는데 의의가 있겠다.

• 대한교통학회지
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• 제5권2호
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• pp.19-35
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• 1987

Transportation energy saving is a national concern because all national petroleum energy is imported. A number of intersections are operating as semi-protected intersections, which have left-turn signal but not exclusive left-turn lanes, because of limited roadways in urban areas. Since the traffic signal methods for the intersections having left-turn signal/lanes cannot be applied to the semi-protected intersection, it is needed to develop a new technique. The purpose of this study was to develop a traffic signal timing method at semi-protected intersections for energy saving and to computerize the method for the practical use. A probability model which could estimate left-turn utilization factors of through traffic during green signal was developed based on field studies. Employing the factors, macro-models to estimate vehicular average delay and proportions of vehicles stopped at the semiprotected intersections were developed. The calculated values of the delay model agreed well with the simulated values of a simulation model using SLAM Ⅱ, a simulation language. Using the two models and the idling fuel consumption rate and the excess fuel consumption per stop-go speed change of vehicles. a traffic signal timing method at semi-protected intersections for energy saving was developed and computerized. The method can be used for other measures of effectiveness such as minimum delay, minimum stop ratio, etc.

• Journal of Communications and Networks
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• 제14권5호
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• pp.501-509
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• 2012

This paper proposes a joint timing synchronization, channel estimation, and data detection for the impulse radio ultra-wideband systems. The proposed timing synchronizer consists of coarse and fine timing estimation. The synchronizer discovers synchronization points in two stages and performs adaptive threshold based on the maximum pulse averaging and maximum (MAX-PA) method for more precise synchronization. Then, iterative channel estimation is performed based on the discovered synchronization points, and data are detected using the selective rake (S-RAKE) detector employing maximal ratio combining. The proposed synchronizer produces two signals-the start signal for channel estimation and the start signal for start frame delimiter (SFD) detection that detects the packet synchronization signal. With the proposed synchronization, channel estimation, and SFD detection, an S-RAKE receiver with binary pulse position modulation binary phase-shift keying modulation was constructed. In addition, an IEEE 802.15.4a channel model was used for performance comparison. The comparison results show that the constructed receiver yields high performance close to perfect synchronization.

• 대한전자공학회논문지SP
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• 제44권5호
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• pp.45-53
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• 2007

DTV수신기에서 송신신호를 완벽하게 복원하기 위해서는 채널의 영향으로 인해 파일롯의 위치가 바뀌고 위상이 틀어지는 것을 보상해주는 반송파 주파수 동기와 샘플링 클락 주파수와의 위상오차로 인해 발생하는 샘플링 타이밍 오차를 보상하는 심볼 타이밍 동기가 모두 획득되어야 한다. 심볼 타이밍 동기부는 일반적으로 다중레벨을 가지는 신호에 사용되는 가드너(Gardner)방법을 사용한다. 가드너 방법은 매 심볼마다 타이밍 에러성분을 추출하므로 다중경로 채널에서 타이밍동기를 추적하면서 유지하는데 유리한 방식이다. 본 논문에서는 가드너 방법에서 에러를 검출하기 위해 사용되는 가드너 타이밍 에러 검출기(Timing Error Detector)가 수신파워레벨이 기준 파워레벨에서 크게 벗어날 경우 동기를 획득할 수 없는 문제점을 해결하기 위해 1단계로 가드너 타이밍 에러 검출기 블록 앞에 수신파워레벨을 계산하여 보정하는 블록을 추가하여 수신파워레벨을 보정한다. 2단계로 반송파 주파수동기와 심볼타이밍동기에 사용되는 PLL(Phase Locked Loop)회로의 빠른 동기 획득과 동기 획득 후 지터량을 줄이기 위하여 루프필터의 출력 값의 평균을 이용하여 옵셋량을 추정하여 추정된 옵셋의 변화율에 따라 단계적 대역폭을 가지는 적응적인 루프필터를 반송파 주파수 동기 회로와 심볼 타이밍동기 회로에 적용함으로써 최적의 동기성능을 얻는다.

• Journal of Positioning, Navigation, and Timing
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• 제6권3호
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• pp.87-94
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• 2017

GNSS modernization and development is in progress throughout the globe, and it is focused on the addition of a new navigation signal. Accordingly, for the next-generation GNSS signals that have been developed or are under development, various combinations that are different from the existing GNSS signal structures can be introduced. In this regard, to design an advanced signal, it is essential to clearly understand the effects of the signal structure and design variables. In the present study, the effects of the GNSS spreading code period and GNSS data bit duration (i.e., signal design variables) on the signal processing performance were analyzed when the data bit transition was considered, based on selected GNSS signal design scenarios. In addition, a method of utilizing the obtained result for the design of a new GNSS signal was investigated.

• Journal of Positioning, Navigation, and Timing
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• 제11권4호
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• pp.381-388
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• 2022

In 2021, development of a regional satellite navigation system called KPS was approved. In this regard, various studies are in progress, but there is no published signal model. So, in relation to the user segment, it is necessary to design a user receiver, but there is no information. Therefore, in this paper, we assume a signal model that can be a candidate signal for KPS based on related studies. This signal uses CNAV-2 structure navigation message, truncated Gold code and BPSK modulation. Based on this signal, a simulator is designed that can be used for receiver design later. The simulator consists of a signal generator and a signal transmitter, and is verified using a software receiver and spectrum analyzer.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권11호
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• pp.4268-4289
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• 2020

Advanced traffic signal timing method plays very important role in reducing road congestion and air pollution. Reinforcement learning is considered as superior approach to build traffic light timing scheme by many recent studies. It fulfills real adaptive control by the means of taking real-time traffic information as state, and adjusting traffic light scheme as action. However, existing works behave inefficient in complex intersections and they are lack of feasibility because most of them adopt traffic light scheme whose phase sequence is flexible. To address these issues, a novel adaptive traffic signal timing scheme is proposed. It's based on actor-critic reinforcement learning algorithm, and advanced techniques proximal policy optimization and generalized advantage estimation are integrated. In particular, a new kind of reward function and a simplified form of state representation are carefully defined, and they facilitate to improve the learning efficiency and reduce the computational complexity, respectively. Meanwhile, a fixed phase sequence signal scheme is derived, and constraint on the variations of successive phase durations is introduced, which enhances its feasibility and robustness in field applications. The proposed scheme is verified through field-data-based experiments in both medium and high traffic density scenarios. Simulation results exhibit remarkable improvement in traffic performance as well as the learning efficiency comparing with the existing reinforcement learning-based methods such as 3DQN and DDQN.

• Journal of Positioning, Navigation, and Timing
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• 제8권4호
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• pp.139-152
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• 2019

The design of new navigation signals is a key factor in building new satellite navigation systems and/or modernizing existing legacy systems. Navigation signal design involves selecting candidate groups and evaluating and analyzing their signal performances. This process can be easily performed through software simulation especially at the beginning of the development phase. The analytical signal performance analysis software introduced in this study is implemented based on equations between the signal design parameters of Radio Navigation Satellite Service (RNSS) and the navigation signal figures-of-merit (FoMs). Therefore, this study briefly summarizes the RNSS signal design parameters and FoMs before introducing the developed software. After that, we explain the operating sequence of the implemented software including the Graphical User Interface (GUI), and calculate the FoMs of an example scenario to verify the feasibility of the software operations.

• Journal of Positioning, Navigation, and Timing
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• 제7권1호
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• pp.1-14
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• 2018

The Global Positioning System (GPS) provides more accurate positioning estimation performance by processing L1 and L2 signals simultaneously through dual frequency signal processing technology at the L-band rather than using only L1 signal. However, if anti-spoofing (AS) mode is run at the GPS, the precision (P) code in L2 signal is encrypted to Y code (or P(Y) code). Thus, dual frequency signal processing can be done only when the effect of P(Y) code is eliminated through the L2 signal processing technology. To do this, a codeless technique or semi-codeless technique that can acquire phase measurement information of L2 signal without information about W code should be employed. In this regard, this paper implements L2 signal processing technology where two typical codeless techniques and four typical semi-codeless techniques of previous studies are applied and compares their performances to discuss the optimal technique selection according to implementation environments and constraints.

• 전기전자학회논문지
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• 제8권1호
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• pp.39-46
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• 2004

본 논문에서는 확장성을 갖는 다목적 코히어런트 모노펄스 레이더 시뮬레이터를 구현 하였다. 실제 목표물이 존재하지 않는 실내 환경에서 운영 가능토록 안테나의 기계적인 회전신호, 펄스 레이더의 운용타이밍 신호 및 표적신호 연구를 통해 이를 모의할 수 있는 TSG(Timing Signal Generator)보드를 개발하여 시뮬레이터에 탑재 하였다. 또한 레이더 기능 알고리듬의 추가나 운용 시나리오 변경에 의한 하드웨어 재구성이나 확장이 용이하도록 다중 DSP 구조의 프로그램 가능한 레이더 신호처리기를 내장 하였다. 모의실험을 통하여, 구현된 코히어런트 모노 펄스 레이더 시뮬레이터가 실제 사용 중인 레이더 전시기(RD9800)상에 움직이는 목표물의 궤적을 정확하게 지시해 주는 것을 확인할 수 있음을 보였다.