• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.5
• /
• pp.465-473
• /
• 2008

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.16 no.3
• /
• pp.59-72
• /
• 2017

As the part of study which handles the measure to use the individual vehicle information of taxi GPS data on signal controls in order to overcome the limitation of Loop detector-based collecting methods of real-time signal control system, this paper conducted series of evaluations and improvements on link travel time, queue vehicle time estimates and traffic condition decision algorithm from the research introduced in 2016. considering the control group and the other, the link travel time has enhanced the travel time and the length of queue vehicle has enhanced the estimated model taking account of the traffic situation. It is analyzed that the accuracy of the average link travel time and the length of queue vehicle are respectably both approximately 95 % and 85%. The traffic condition decision algorithm reflected the improved travel speed and vehicle length. Smoothing was performed to determine the trend of the traffic situation and reduce the fluctuation of the data, and the algorithms have refined so as to reflect the pass period on overflow judgment criterion.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.04a
• /
• pp.125-128
• /
• 2015

최근 GPS가 기본 탑재된 스마트폰이 활성화된 이후 대량의 GPS 궤적 데이터를 전자지도에 매칭하여 분석하는 요구가 대두되고 있다. 그러나 기존에 연구된 맵매칭 기법은 주로 내비게이션용 알고리즘으로 대량의 GPS궤적을 서버에서 분석하기에는 속도 및 시스템 성능의 이슈가 있다. 본 연구는 대표적인 분산 NoSQL DB인 하듐 에코시스템의 HBase를 이용한 맵매칭 시스템에 대한 연구이다. 맵매칭을 위한 전자지도를 HBase탑재하기 위한 테이블 사양을 정의하였고, HBase와 연동하여 분석하는 맵매칭 알고리즘을 제시하고 Java로 구현하여 분석하였다. 이를 통해 대량의 GPS궤적을 NoSQL 기반 방법론을 통하여 효율적으로 빅데이터를 분석하였다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.180-180
• /
• 2012

ADCP는 3차원 유속과 수심을 관측하여 유량을 정확하게 계산하는 데 널리 이용되고 있는 최신계측기기로 국내에서도 유량조사사업단 등 기관에 도입되어 수위-유량관계곡선식의 보정 등에 적용되고 있다. 하지만 ADCP 관측값 중 수심관측 자료를 별도로 활용하는 부분도 많은 관심을 받고 있다. 특히 최근 4대강 사업으로 인한 하상변동 측정에 기존 유량관측용으로 구매된 ADCP를 수심관측용으로 활용할 수 있다. ADCP는 일정한 각도로 경사진 4개의 초음파 빔을 활용하여 사선 방향으로 수심을 각각 관측한다. 최근에는 별도의 수심관측용의 수직 빔을 추가 설치하여 한번 관측에 초당 5개 지점의 수심을 동시에 관측할 수 있어 수심관측용으로도 기존 단독빔 음향측심기에 비해 효율적으로 수심을 관측할 수 있다. 그리고 ADCP는 GPS와 연동되어 수심관측의 3차원 공간정보 (x, y, z)를 창출할 수 있어 기존 GIS 자료와 융합될 수 있다. 하지만 기존의 음향 측심기의 수직빔과 다르게 ADCP의 빔이 일정한 각도로 경사져 있고 선박 활용 관측 시 요동에 의해 흔들려 각각의 빔이 계측한 수심의 수평위치를 정확하게 추출하기 어려운 점이 있다. 특히 경사빔에 의한 수심관측지점에 GPS 정보를 추정하여 부여하는 작업도 까다롭다고 하겠다. 그리고 수심관측자료 자체의 오차나 특이점 제거 등의 보정작업을 거쳐야 하는 문제도 있다. 따라서 원자료를 직접 활용할 수 없고 별도의 후처리 과정을 거쳐야 한다. 따라서 본 연구는 이러한 문제를 해결하기 위해 다음의 알고리즘을 개발하였다: 1) 경사빔에 의한 관측지점의 수평위치 산정, 2) ADCP의 흔들림 (피치와 롤링) 보정, 3) 경사빔의 관측위치에 지리정보부여, 4) 수심관측치 오차와 특이점 보정, 5) 관측자료의 GIS 파일 전환. 이러한 알고리즘은 GUI와 연동되어 적용되었으며 편리하게 이용되도록 구성되었다. 그리고 본 연구는 이러한 ADCP의 수심관측 자료와 하천 및 저수지 등 경계 GIS 파일을 연동시켜 전체 혹은 국부 저수량과 하상변동량을 계상하는 알고리즘도 추가하여 관측자료의 실무에서의 활용성을 증대시키고자 하였다.

• Journal of Advanced Navigation Technology
• /
• v.21 no.4
• /
• pp.339-346
• /
• 2017

We propose the design of an INS simulated equipment to evaluate the enhanced jamming resistance of an INS-aided GPS receiver with INS, when a jamming signal is injected into a simulated high dynamic platform. We propose the design of a relative cheap INS simulated equipment, instead of an expensive INS simulator connected to GPS simulators. Based on the design, we implement the equipment and setup high dynamic test environment using the equipment to evaluate an INS-aided GPS receiver. In the GPS L1 C/A and L2C simulations that inject jamming signals of the narrow and wide bandwidth into the GPS receiver with and without INS-aided algorithm, we obtain increased jamming resistance performance as +5 dB compared with the GPS receiver without INS-aided algorithm in all kinds of jamming bandwidth. Based on the simulations, we verified that the INS simulated equipment can be used to evaluate the enhanced jamming resistance of INS-aided GPS receivers.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.8 no.6
• /
• pp.121-130
• /
• 2009

In this paper, Gaussian probability distribution model based multi-sensor data fusion algorithm is proposed for a vehicular location awareness system. Conventional vehicular location awareness systems are operated by GPS (Global Positioning System). However, the conventional system is not working in the indoor of building or urban area where the receiver is difficult to receive the signal from satellites. A method which is combined GPS and UWB (Ultra Wide-Band) has developed to improve this problem. However, vehicular is difficult to receive seamless location information since the measurement systems by both GPS and UWB convert the vehicle's movement information separately at each sensor. In this paper, normalized probability distribution model based Hybrid UWB/GPS is proposed by utilizing GPS location data and UWB sensor data. Therefore the proposed system provides information with seamless and location flexible properties. The proposed system tested by Ubisense and Asen GPS in the $12m{\times}8m$ outdoor environments. As a result, the proposed system has improved performance for accurateness and connection ability between devices to support various CNS (Car Navigation System).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.522-525
• /
• 2015

In this paper, we propose a walking aid system that guides route to visually impaired people in order to recognize uncertain obstacles based on tactile stimulation. The proposed system is composed of the touch-based obstacle detection module, the obstacle height detection module, and the route guidance algorithms. The touch-based obstacle detection module detects each obstacle, which is located at left, right, and front of a visually impaired person by stimulating his thumb with the rotational force of the servomotor. The obstacle height detection module integrates detected data by the linear arrangement of ultrasonic sensors to identify the height of an obstacle about 3 of-phase(i.e., high, medium, low). The proposed route guidance algorithm guides an optimized path to the visually impaired person by updating his current position information based on the signal of the built-in GPS receiver in smartphone. In addition, the route guidance algorithm delivers information with speech to a visually impaired person through Bluetooth commuination in the developed route guidance app. The proposed system can create a path to avoid the obstacles by recognizing the placed situation of the obstacles with exploring the uncertain path.

• Current Research on Agriculture and Life Sciences
• /
• v.31 no.2
• /
• pp.131-138
• /
• 2013

The precision aerial application of small farms, such as paddy, upland and orchard fields using agricultural unmanned helicopters became a new paradigm. The objective of this study was to evaluate the performance of a GPS module and algorithm, controlling drift of agricultural helicopter by the crosswind and maintaining the position for emergency landing. Purpose of the drift control, of which an algorithm works while hovering is related with the emergency sequence that coping with abnormal conditions of rotorcraft system. However, the inertial attitude control cannot detect a drifting motion of fuselage moving at the constant velocity, thus the crosswind takes the helicopter away from the landing position. Performance of the drift control module, based on the GPS that a hovering position did not deviate within 5m in diameter, were tested and evaluated. Initially, the reaction against a disturbing gust wind was sensitive, soon the helicopter maintained its locking position and azimuth within 5m in diameter. It was, however, difficult for the helicopter to recognize the swaying and nodding, the some deviation was expected due to the discrepancy characteristics of the GPS signal. The performance of the drift control proved the effectiveness of the module to maintain the position against an unintended drift during the emergency landing or hovering.

• Journal of KIISE:Software and Applications
• /
• v.36 no.6
• /
• pp.462-470
• /
• 2009

We propose a wearable system to help the visually impaired persons for walking safely to destination. If a user selects a destination, the system guides the user to destination with position data from GPS receiver and shortest path algorithm. At the same time, after acquiring complex spatial structures in front of the user with ultrasonic sensors, we categorize them into several predefined patterns, and determine an avoidance direction by estimating the patterns. As a result, visually impaired persons can arrive at destination safely and correctly without others help.

• Journal of Navigation and Port Research
• /
• v.38 no.4
• /
• pp.373-378
• /
• 2014

In order to prepare for recapitalization of differential GNSS (DGNSS) reference station and integrity monitor (RSIM) due to GNSS diversification, this paper focuses on differential correction algorithm using GPS/Galileo pesudorange. The technical standards on operation and broadcast of DGNSS RSIM are described as operation of differential GPS (DGPS) RSIM for conversion of DGNSS RSIM. Usually, in order to get the differential corrections of GNSS pesudorange, the system must know the real positions of satellites and user. Therefore, for calculating the position of Galileo satellites correctly, using the equation for calculating the SV position in Galileo ICD (Interface Control Document), it estimates the SV position based on Ephemeris data obtained from user receiver, and calculates the clock offset of satellite and user receiver, system time offset between GPS and Galileo, then determines the pseudorange corrections of GPS/Galileo. Based on a platform for performance verification connected with GPS/Galileo integrated signal simulator, it compared the PRC (pseudorange correction) errors of GPS and Galileo, analyzed the position errors of DGPS, DGalileo, and DGPS/DGalileo respectively. The proposed method was evaluated according to PRC errors and position accuracy at the simulation platform. When using the DGPS/DGalileo corrections, this paper could confirm that the results met the performance requirements of the RTCM.