• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.53-57
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• 2013

The quality of service for the voice and data communication is one of the most important elements in the mobile cellular networks. This quality has the time varying characteristics depending on the wireless network environments. In order to guarantee the quality of service at the predefined level, the mobile service provider needs to collect all the information about the level of quality served by the local base stations. In the conventional method the information on the service quality is measured and collected by the moving vehicle adopting the global positioning device. However this method requires relatively high cost and does not cover all the service areas. In this paper a new method is proposed utilizing a measurement node with local area communication transceiver and the mobile user equipment. In the proposed method the node communicates with the user equipment periodically to monitor the information on the service quality. The resulting information is reported to the measurement server in the mobile network. This method could be applied to either the circuit or the packet based networks. It also has an advantage in terms of the cost efficiency compared to the conventional method considering the required the equipment and the human resources.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.43-49
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• 2017

Generally, loop filter based scalar tracking loops (LF-STL) have been used for global positioning system (GPS) signal tracking algorithm. This paper introduces the accuracy and robustness of linear-quadratic-Gaussian based vector tracking loop (LQG-VTL) algorithm instead of LF-STL. To verify the accuracy of LQG-VTL, we confirm that the measurements estimation errors of the LQG based scalar tracking loops (LQG-STL) are improved by more than 60 % compared to LF-STL. Also, when LQG-VTL is used, measurements estimation errors decrease compared to LQG-STL, and position/velocity estimation errors also decrease as the number of satellites increases. To verify the robustness of LQG-VTL, we confirm that LQG-VTL can estimate position/velocity and measurements successively compared to LF-STL in temporal signal attenuation of 30 dB-Hz during 4 seconds.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.4
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• pp.26-32
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• 2016

An autonomous car(driverless car, self-driving car, robotic car) is a vehicle that is capable of sensing its environment and navigating without human input. Autonomous cars can detect surroundings using a variety of techniques such as radar, lidar, GPS, odometry, and computer vision. Advanced control systems interpret sensory information to identify appropriate navigation paths, as well as obstacles and relevant signage. Autonomous cars have control systems that are capable of analyzing sensory data to distinguish between different cars on the road, which is very useful in planning a path to the desired destination. An issue tree, also called a logic tree, is a graphical breakdown of a question that dissects it into its different components vertically and that progresses into details as it reads to the right.Issue trees are useful in problem solving to identify the root causes of a problem as well as to identify its potential solutions. They also provide a reference point to see how each piece fits into the whole picture of a problem. Using Issue-Tree menthods, transportation safety policies were developed with autonompus vehicle in mind.

• Journal of Korea Spatial Information System Society
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• v.6 no.1 s.11
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• pp.73-85
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• 2004

Recently, as the growth of the wireless Internet, PDA and HPC, the focus of research and development related with GIS(Geographic Information System) has been changed to the Real-Time Mobile GIS to service LBS. To offer LBS efficiently, there must be the Real-Time GIS platform that can deal with dynamic status of moving objects and a location index which can deal with the characteristics of location data. Location data can use the same data type(e.g., point) of GIS, but the management of location data is very different. Therefore, in this paper, we studied the Real-Time Mobile GIS using the HBR-tree to manage mass of location data efficiently. The Real-Time Mobile GIS which is developed in this paper consists of the HBR-tree and the Real-Time GIS Platform HBR-tree. we proposed in this paper, is a combined index type of the R-tree and the spatial hash Although location data are updated frequently, update operations are done within the same hash table in the HBR-tree, so it costs less than other tree-based indexes Since the HBR-tree uses the same search mechanism of the R-tree, it is possible to search location data quickly. The Real-Time GIS platform consists of a Real-Time GIS engine that is extended from a main memory database system. a middleware which can transfer spatial, aspatial data to clients and receive location data from clients, and a mobile client which operates on the mobile devices. Especially, this paper described the performance evaluation conducted with practical tests if the HBR-tree and the Real-Time GIS engine respectively.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.131-143
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• 2011

Previous alerting service based on LBS was caused severe overload problem of server by using the method to confirm the location of each moving object on server. In this paper, by loading an App on smart moving object, we proposed a novel algorithm named ADAS(Active Disaster Alert Service) for accessing to the server site with oneself location information as needed and implemented the disaster alerting service system with visualization for user. In the proposed method, running App access to the server periodically with the present location coordinate gained from GPS module or network module and the ID of moving object. Then, the server compare the present location coordinate of moving object and the coordinates of disasters registered in DIDB and transmit the n NDIs existed in near distance orderly from the coordinate of present moving object to the client. The App compares the coordinate of present location for moving object and the coordinates of NDI is transmitted from server by real time and executes the service with classifying levels of alert into three steps such as danger, carefulness and safety. And new NDIs are gained by accessing DIDB on Server periodically during running App. Therefore, this will be become a novel method for reducing fundamentally the server overload problem in comparison with previous alerting service that the career of moving object is managed on server.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.171-178
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• 2017

In this paper, in order to verify the performance of a localization algorithm using GPS as an auxiliary sensor, the algorithm was applied to a hovering-type autonomous underwater vehicle (AUV) to perform a field test. The applied algorithm is an algorithm to improve the accumulated positional error of dead reckoning using doppler velocity logger(DVL) and tilt-compensated compass module (TCM) mounted on the AUV. GPS when surfaced helps the algorithm to estimate the position and the heading bias error of TCM for geodetic north, which makes it possible to perform dead reckoning on north-east-down (NED) coordinates. As a result of field test performing heading control, it was judged that the algorithm could improve the positional error, enhance the operational capability of AUV and contribute to the research of underwater navigation depending on a magnetic compass.

• Journal of Digital Convergence
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• v.13 no.1
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• pp.297-304
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• 2015

Recently, the demand for a PRT(Personal Rapid Transit) system based on autonomous navigation is increasing. Accordingly, the applicability investigations of the PRT system on rail tracks or roadways have been widely studied. In the case of unmanned vehicle operations without physical guideways on roadways, to monitor the position of the vehicle in real time is very important for stable, robust and reliable guidance of an autonomous vehicle. The Global Positioning System (GPS) has been commercially used for vehicle positioning. However, it cannot be applied in environments as tunnels or interiors of buildings. The PRT navigation system based on magnetic markers reference sensing that can overcome these environmental restrictions and the vehicle dynamics model for its H/W configuration are presented in this study. In addition, the design of a control S/W dedicated for unmanned operation of a PRT vehicle and its prototype implementation for experimental validation on a pilot network were successfully achieved.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.611-618
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• 2012

ICAO has recommended the introduction of New CNS/ATM based on GNSS technologies and Data link communication to purpose increasing air traffic demand. The CNS/ATM is composed of communication, Navigation, Surveillance and Air Traffic Management. Cockpit Display Traffic Information(CDTI) that is equipment to share air traffic information to Pilot, Traffic Controller and ground vehicles has been built based on Automatic Dependent Surveillance-Broadcast(ADS-B) information in Surveillance field. This paper is research that what is the effect between pilot and controller through CDTI. Based on ATC communication between Pilot and Controller, We construct simulation environment and did a comparative analysis of it. according to result, We can verify that CDTI makes aircraft Call sign, Position, Altitude information read rate, and notice of air traffic information between Pilot and Controller more improve than ATC environment and Existing Radar System.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• v.10 no.2
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• pp.59-63
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• 2005

가. 자율주행 트랙터가 작업하는 동안 작동상태를 효과적으로 모니터링하고 제어할 수 있도록 하기 위해 인터넷을 통한 자율주행 트랙터의 모니터링과 원격제어 기술에 대하여 시험 하였다. 나. 트랙터를 모니터링하고 제어하는 곳과 경작지가 있는 곳을 인터넷으로 연결하고, 운전자가 탑승하지 않은 트랙터는 인터넷을 통해 전달받은 명령을 수행하도록 액튜에이터를 제어하고 제어되는 상황을 경작지에 위치한 카메라가 촬영하여 인터넷을 통하여 원격지의 운전자 쪽으로 전송하도록 시스템을 구성했다. 다. HST 트랙터 조종장치로서 서보제어가 가능한 액튜에이터를 개발 장착하고 제어성능을 시험하였다. 전자유압제어(EHPS)식 조향액튜에이터는 , 조향가능각 100도의 전범위에 조향 제어가 가능했으며 전조향에 필요한 시간은 약 1.6초 정도 였다. 피스톤 펌프의 사판각을 제어하는 전후진 제어기는 리니어 모터 구동식으로 총 제어 변위 50mm를 이동하는데 제어시간이 약 1.2초 소요되었다. 엔진 회전수를 제어하기위한 스로틀 액튜에이터는 리니어 모터 구동식으로 제어변위 30mm에 대해 제어시간이 0.8초 소요되었다. 3점 링크에 부착된 작업기의 위치를 제어하는 리프트 제어기도 리니어모터로 구동하였으며 제어거리 40mm에 대해 제어시간 0.9초정도가 소요되었다 라. 제작된 HST 무인 트랙터를 인터넷과 무선통신 시스템을 이용하여 원격 모니터링과제어 가능성에 대해 시험 했다. 인터넷을 통한 장거리 원격제어 및 모니터링 시험에서 제어신호의 전달지연은 0.3 ${\sim}$ 0.5초정도로 제어신호의 피이드 백을 확인할 때까지는 약1초정도의 대기 시간이 필요한 것으로 나타나 모니터링 및 제어 시스템의 개발 시 이를 고려할 설계가 필요한 것으로 나타났다.된 표층수온 분포값보다 2005년 2월에 관측된 표층수온 분포값이 상대적으로 낮은 분포 특성을 나타내고 있었다. 따라서 인공위성자료를 이용한 황해의 2004년 해황 분석 결과는 이상수온 상승의 원인이 쿠로시오 해류의 변동과 관련성이 높다고 판단되며 이에 대한 지속적인 연구가 현재 진행중에 있다.에 인산염 처리, 여기에 초음파 처리, 마지막 단계로 3분 끓이면 억제율이 68%까지 억제되었다. 이는 단일처리시 전혀 억제를 못하는 처리를 단계별로 한 단계씩 더해가면 allergy 억제효과가 나타난다고 할 수 있겠다. 초음파 처리도 역시 저 allergy 처리 공정에 이용될 수 있는데 이것은 그 처리로 인해 새로운 알러젠이 생성될 수도 있다. 또한 복합처리로 allergy를 감소시키면 연속적이고 동시적으로 하기 때문에 원가를 절감할 수 있다.환경현안에 대한 정치경제적 접근을 외면하지 말고 교과서 저작의 소재로 삼을 수 있어야 하며, 이는 '환경관리주의'와 '녹색소비'에 머물러 있는 '환경 지식교육'과 실천을 한단계 진전시키는 작업으로 이어질 것이다. 이후 10년의 환경교육은 바로 '생태적 합리성'과 '환경정의'라는 두 '화두'에 터하여 세워져야 한다.배액에서 약해를 보였으나, 25% 야자지방산의 경우 50 ${\sim}$ 100배액 어디에서도 액해를 보이지 않았다. 별도로 적용한 시험에서, 토마토의 경우에도 25% 야자지방산 비누 50 ${\sim}$ 100배액 모두 약해를 발생하지 않았으나, 오이에서는 25% 야자지방산 비누 100배액에도 약해를 나타내었다. 12. 이상의 결과, 천연지방산을 이용하여 유기농업에 허용되는 각종의 살충비누를 제조할 수 있었으며, 방제가 조사결과 진딧물, 응애 등 껍질이 연약한