• Journal of Advanced Navigation Technology
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• v.20 no.1
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• pp.29-36
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• 2016

Accuracy of GPS (global positioning system) deteriorates dramatically or positioning is impossible in urban area occasionally since high-rise buildings and elevated roads make the reception of navigation signal very difficult so that number of visible satellites decreases. In these cases, vertical error usually becomes much larger than the horizontal error due to the intrinsic geometry of GPS satellites. To obtain more accurate and reliable height information, this paper proposes a hybrid method that combines GPS and a low-cost barometric altimeter. In the proposed method, the sea-level pressure and the sea-surface temperature are applied to the output of the altimeter. Next, the difference between the ellipsoid and the geoid is compensated. Finally, a simple Kalman filter combines the compensated barometric altitude and the GPS height. By static and car experiments, performance of the proposed method is evaluated. By the experiment results, it can be seen that the proposed method improves the altitude accuracy considerably.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1D
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• pp.21-27
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• 2008

To respond to years-long economic decline in the downtown Seoul, it is necessary to lay out a scheme revitalizing downtown economy. It is called Wanavi and Shonavi system. When customers do shopping, it is the "Shonavi" that provides shopping information such as popular shop name, location, and commodity price to walkers in a real-time base. In addition, the walking navigation system called "Wanavi" is designed to provide access information for walking shoppers, the function of which is similar to car navigation system. The "Wanavi" can help walkers find the fastest, comfortable and attractive pedestrian route and public transportation information reaching to the destination in the downtown. In this study, we propose GPA & RFID mixed system as a communication technique to activate "Shonavi" and "Wanavi" system. The "Shonavi" and "Wanavi" system will be one of the ways to revitalize depressed downtown economy in Seoul.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.4
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• pp.361-365
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• 2002

오랜 세월동안 위대한 이동수단을 만들어내고자 하는 인간의 꿈은 오늘날 눈부신 각종 운송기구를 만들어 내는 결실을 얻고 있다. 자동차 네비게이션 시스템도 그러한 결실중의 한 예라고 할 수 있을 것이다. 지능적으로 판단하고 정보를 처리할 수 있는 자동차 네비게이션 시스템을 부착함으로써 한 단계 발전한 운송수단으로 진화할 수 있을 것이다. 이러한 자동차 네비게이션 시스템의 단점이라면 한정된 리소스만으로 여러 가지 작업을 수행해야만 하는 어려움이다. 그래서 네비게이션 시스템의 주요 작업중의 하나인 경로를 추출하는 경로추출(Route Planning) 작업은 한정된 리소스에서도 최적의 경로를 찾을 수 있는 지능적인 방법이어야만 한다. 이러한 경로를 추출하는 작업을 하는데 기존에 일반적으로 쓰였던 두 가지 방법에는 Dijkstra s algorithm과 A*algorithm이 있다. 이 두 방법은 최적의 경로를 찾아낸다는 점은 있지만 경로를 찾기 위해서 알고리즘의 특성상 각각, 넓은 영역에 대하여 탐색작업을 해야 하고 또한 수행시간이 많이 걸린다는 단점과 또한 경로를 계산하기 위해서 Heuristic function을 추가적인 정보로 계산을 해야 한다는 단점이 있다. 본 논문에서는 적은 탐색 영역을 가지면서 또한 최적의 경로를 추출하는데 드는 수행시간은 작으며 나아가 동적인 교통환경에서도 최적의 경로를 추출할 수 있는 최적 경로 추출방법을 강화학습의 일종인 Q- Learning을 이용하여 구현해 보고자 한다.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.95-99
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• 2013

GPS service is generally being used in the navigation application such as the car navigation and the smart phone. Recently, GPS service continues to increase in the timing application such as the mobile telecommunication network, the smart grid, and the financial network. As GPS signals are sensitive to GPS jamming, it should be monitored and protected. In oder to prevent and minimize the damage caused by GPS jamming, many countries are developing and operating GPS jamming monitoring system. This paper presents the implementation and the test results of the GPS jamming equipment which provides the detection, the direction finding and the location of GPS jamming.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.4 s.304
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• pp.1-10
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• 2005

This paper presents a map matching method using multiple hypothesis technique(MHT) to identify the road that a land vehicle is located on. To realize a map matching method using MHT, Pseudo-measurements are generated utilizing adjacent roads of GPS/DR position and the MHT is reformulated as a single target problem. Since pseudo-measurements are generated using digital map, topological properties such as road connection, direction, and road facility information are considered in calculating probabilities of hypotheses. In order to improve the map matching performance under when bias errors exist in digital road map data, a Kalman filter is employed to estimate the biases. Field experimental results show that the proposed map matching method provides the consistent performance even in complex downtown areas, overpass/underpass areas, and in the areas where roads are adjacent in parallel.

• Journal of the Korean Institute of Navigation
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• v.18 no.2
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• pp.19-40
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• 1994

Several factors can be chosen for evaluating seakeeping performance, such as deck wetness, propeller racing, slamming, rolling, vertical acceleration and vertical bending moment, in consi-deration of the safety of human being, cargo and ship. In fact, there are few developments for an evalua-tion method of seakeepting performance correponding with each ship's characteristics. The purpose of this paper is to develop an quantitative evaluation method of seakeeping performance according to ship types. The scope and the method of this study are as follow. (1) Obtain each response amplitude of ship's motion in waves by Ordinary Strip Method and apply it to short-crested, irregular wave for random process of the factors on seakeeping performance. (2) Define the evaluation index, the dangerousness, the maximum dangerousness and the evaluation diagram. (3) Figure out the different characteristics according to ship types by computer simulation of evaluating seakeeping performance. (4) Adopt vertical acceleration and one of rolling or lateral acceleration as the factors on seakeeping performance by clarifying the correlation of stochastic process. This study developed an evaluation method coincident with each ship's characteristics, and suggested a device for application to actual ship. This method might be useful in developing the practical system of seakeeping performance in accordance with ship types. The ship models for computer simulation are 175m container ship types, 93m tranning ship HANARA as passenger ship type, 259m bulk-carrier type and 164m pure car-carrier type.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.4
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• pp.108-113
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• 2011

In this paper, we propose a new method for robot navigation control through EMG and acceleration sensors which is attached to wrist. The method can remote control with intuitive motion like driving a car. It decide to control whether or not through EMG signal processing. And motion inferring through signal processing from acceleration sensor. Inferred motion is mapped to control command such as 'Forward', 'Backward', 'Left', 'Right'. Accuracy of each motions are over 99%. Control is capable naturally without time delay. Entire system has been implemented and we verified its utility through demonstration.

• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.471-478
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• 2020

In this paper, we develop the ground risk model of unmanned aerial vehicle (UAV) operation to quantify the ground risk when the UAV falls to the ground during the intended operation in case of UAV failure. The ground risk is computed by using the UAV failure probability, the probability of impact a person when UAV falls to the ground, the probability of fatality when UAV strikes the person. We mathematically derive each probability to evaluate the ground risk of UAV operation. Also, the population density map, building to land ratio map, car traffic database is used to estimate the number of people exposed to collision with UAV. Finally, we assumed the operations of a UAV with two paths in Daejeon city and evaluate the ground risk of each UAV operations.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.99-107
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• 1996

When GPS (global positioning system) is used as synchronous signal in CDMA digital cellular base station system and high speed digital synchronous communication network, antenna cable length is increased, comparing with other GPS application such as positioning or car navigation. In this paper, it is proposed that a type of new GPS antenna system including RF stage for reduction of cable loss in case of long cable.The antenna system with TMPA(truncated-corners microstrip patch antenna) is designed and fabricated because GPS signal has RHCP (right-hand circular polarization), consequently antenna size can be made small size. LNA (low noise amplifier) is designed by using HEMT(high electron mobility transistor)which has lower noise figurae and better AGC characteristics at low voltage than GaAs FET, and we equiped mixer, in GPS antenna unit, which converts from 1575.42MHz to 75.42MHz. As result of comparing between typical system and proposed system when cable length is 60m, 63dB, 55dB and 25dB gain are obtained for RG-316/U, RG-58C/U and RG-213/U, and better characteristics are achieved than typical system as far as cable length is longer.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.2
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• pp.269-275
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• 1997

Car Navigation System with Global Positioning System (GPS) can display position direction and the shortest cut of one's destination. The position datum for GPS in World Geodetic System 1984 (WGS-84) coordinates system need to transform Bessel coordinates system and process Map projection. Since 1987, GPS has used the WGS-84. WGS-84 is a geocentric equipotential ellipsoid of revolution which is defined four parameters. In this study, by comparing the digitized topographical map with the digital map of GPS datum we can consider the technique of WGS84 digital map.