• Progress in Medical Physics
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• v.8 no.2
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• pp.19-26
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• 1997

3-dimensional Neuronavigator, Viewing Wand(ISG Technologies, Toronto, Cannda) is the surgery aid equipment for real time image (CT or MRI) guided surgery. The assurance of spatial accuracy of this system is important for clinical application. In this study, we have designed the acrylic brain phantom and measured the spatial error with that phantom. The phantom has designed to have capability to simulate image guided surgery. The phantom has 22 vertical rods whose diameters are 5mm and each rods has different length. CT scans were performed by 2.0mm slice and reconstructed for 3-Dimensional analysis. End point of rods can be obtained using reconstructed 3- Dimensional images and they are compared to actual position data. Average deviation was less than 2mm for various situations. Spatial error of Viewing Wand is acceptable in the clinical points of view, while cosmetics of the software needs to be modified to more user friend. Better accuracy can be expected when we apply the mixed fiducial fit registration and surface fit registration method. And even better results can be obtained if registration points distributed even and symetric around the target.

• Journal of Advanced Navigation Technology
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• v.18 no.4
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• pp.312-318
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• 2014

The altitudes of GEO satellites are higher than those of GPS satellites. Therefore the visibility and the received power of GPS signals are totally different from those of the users near the Earth's surface. In this study, we analyzed the visibility of GPS signals received on GEO satellites. And we also developed a software GPS receiver that works on GEO satellites using CCMDB algorithm which is a weak signal receiver algorithm. GPS signals received on a GEO satellite are generated by a commercial hardware GPS simulator and used for the verification of the developed software GPS receiver. The mean 3D position and velocity error are calculated as 165.636 m and 0.5081 m/s.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.15-21
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• 2002

Re Ministry of Maritime Affairs and Fisheries in Korea completed the installation of 8 maritime DGPS station mfd is to going install 3 additional Maritime DGPS station for the enhancement of dual coverage in Korean coasts until Oct. 2002. Moreover, Korean government decided to provide the NDGPS service over the whole Korean inland area, which will be schedule to complete until June. 2004. On this paper to evaluate the propagation characteristics of using maritime DGPS site as un element of NDGPS ann to evaluate the required number of additional NDGPS sites, the propagation characteristics of the radio waves of 300kHz bands on sea and land nth are studied With the result of study, the conceptional design of Korean NDGPS System is proposed, which consists of 5 NDGPS sites with modified antenna and tかee coverage monitoring sites.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.29-35
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• 2013

In this paper, we investigate the type and detection methode of spoofing attack, and then analyze the performance of spoofing detection algorithm in GPS L1 signal through the simulation. Generally spoofer is different from the jammer, because the receiver can be operated and not. In case of spoofing the GPS receiver is hard to recognize the spoofing attack and can be operated normally without stopping because the spoofing signal is the mimic GPS signal. To evaluate the performance of spoofing detection algorithm, both the software based spoofing and GPS signal generator and the software based GPS receiver are implemented. In paper, we can check that spoofing signal can affect to the DLL and PLL tracking loop because code delay and doppler frequency of spoofing. The spoofing detection algorithm has been implemented using the pseudorange, signal strength and navigation solution of GPS receiver and proposed algorithm can effectively detect the spoofing signal.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.1
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• pp.27-40
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• 2013

This study is about development of technology system for an advanced deep-sea unmanned underwater robot of S. Korea analysed by the application of scenario planning. It was developed a 6000m class next-generation deep-sea unmanned underwater vehicle(or robot, UUV) system, soonly ROV 'Hemire' and Depressor 'Henuvy' in 2006 at S. Korea and motion control, adaptive control algolithm, a work-space manipulator control algolithm, especially the underwater inertial-acoustic navigation system robust to initial errors and sensor failures. But there are remained matters on position tracking of the USBL, inertial-acoustic navigation system, attitude sensor, designed sonar sensors. So this study suggest the new idea for settle the matters and then this idea help the development of the underwater inertial-acoustic navigation system robust to initial errors and sensor failures, such as acoustic signal drop-out, by modifying the error covariance of the failed sonar signal when drop-out occurs. As a result, the future policy for deep-sea unmanned underwater robot of S. Korea is to further spur the development of new technology and more improvement of the technology level for deep-sea unmanned underwater robot system with indicator and imaginary wall as external device.

• Journal of Advanced Navigation Technology
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• v.13 no.3
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• pp.311-318
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• 2009

This paper shows the research about the development of software receiving platform processing GPS/Galileo L1/E1/E5a signal. Various researches for new GNSS signal character are possible using software receiving platform by facile program code modification. In addition, the program that processes GPS and Galileo signal integration is expected to help developing integration of receiver algorithm that deal with new various GNSS signal. In this paper, it is introduced the structure of GPS/Galileo receiving platform using sampled IF data as a program input. The function of the software platform embodied using MATLAB tool is tested by live data from Galileo test satellites. The software platform is modulated according to their roll and function. Each module is able to use selective function on GNSS signal.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.2
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• pp.163-171
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• 2014

Based on the GPS/IMU integration, the car navigation has unstable conditions as well as drastically reduces accuracies in urban region. Nowadays, many cars mounted the camera to record driving states. If the ground coordinates of street furniture are known, the position and attitude of camera can be determined through SPR(Single Photo Resection). Therefore, an estimated position and attitude from SPR can be applied measurements in Kalman filter for updating errors of navigation solutions from GPS/IMU integration. In this study, the GPS/IMU/SPR integration algorithm was developed in loosely coupled modes through extended Kalman filters. Also, in order to analyze performances of GPS/IMU/SPR, simulation tests were conducted in GPS signal reception environments and the GCPs (Ground Control Points) distributions. In fact, the position and attitude gathered from GPS/IMU/SPR integration are more precise than the position and attitude from GPS/IMU integration. When IPs (image points), corresponded to GCPs, were concentrated in the center of image, the position error in the optical axis respectively increased. To understand effects from SPR, we plan to carry additional test on the magnitude of GCP, IP and initial exterior orientation errors.

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.33-38
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• 2018

This paper introduces the simulation concepts and technical approach of wire-guided torpedo performance analysis simulator, as a consequence, provide a framework for understanding overall attack procedures and effectiveness of tactics to torpedo operator. It described the mathematical models of simulation components and weapon engagement principle, especially it derived the closed-form solution of time consumption and leading angle problem of torpedo attack situation based on geographical assumption. In addition, it adopted the proportional navigation guidance at final stage of torpedo attack and also consider the tradeoff relation between target ship speed(propeller noise level) and detection probability, so that it improves the fidelity of physical realism. Simulator is developed with high degree of freedom in the perspective of tactical situation, and it helps user to understand the overall situation and tactical effectiveness.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.97-103
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• 2006

The integrated navigation system(INS) for fishing boat which organized the marine radar, global positioning system(GPS) compass, automatic identification system(AIS), echo sounder, GPS and electronic nautical chart(ENC) was manufactured to reduce the marine accidents of fishing boats occurred frequently at coastal and offshore. The application possibility of INS for fishing boat was examined for basic experiments in the sea. Integration display of various information, such as other vessel's behavior, depth, own vessel's position etc. was done to help the operate user who understood the circumstance around own boat. Therefore, the system will be utilized as a useful equipment for safety voyage and fishing work on the fishing ground.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.133-140
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• 2012

This paper suggests an algorithm that can shorten the complexity $O(n^2)$ of Dijkstra algorithm that is applied to the shortest path searching in real-time GPS Navigation System into an up-to-date O(n). Dijkstra algorithm manipulates the distance of the minimum length path by visiting all the nodes from the starting node. Hence, it has one disadvantage of not being able to provide the information on the shortest path every second, in a city that consists of sophisticated roads, since it has to execute number of node minus 1. The suggested algorithm, firstly, runs by means of organizing the set of out-neighbourhood nodes at each level of the tree, and root node for departure node. It also uses a method of manipulating the distance of the minimum path of all out-neighborhoods and interior of the out-neighborhoods. On applying the suggested algorithm to two sophisticated graphs consisted of bi-direction and uni-direction, we have succeeded to obtain the distance of the minimum length path, just as same as Dijkstra algorithm. In addition, it has an effect of shortening the time taken 4 times from number of node minus1 to number of level minus 1. The satisfaction of the drivers can be increased by providing the information on shortest path of detour, every second, when occurs any rush hour or any traffic congestion due to car accident, by applying this suggested algorithm to the real-time GPS system.