• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.48-53
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• 2009

The CMOS RF front-end for Global Positioning System(GPS)are implemented in 1P8M CMOS $0.13{\mu}m$ process. The LNAs consist of LNA1 with high gain and low NF, and LNA2 with low gain and high IIP3 for supporting operation with active and passive antenna. the measured performances of both LNAs are 16.4/13.8 dB gain, 1.4/1.68 dB NF, and -8/-4.4 dBm IIP3 with 3.2/2 mA form 1.2 V supply, respectively. The quadrature downconversion mixer is followed by transimpedance amplifier with gain controllability from 27.5 to 41 dB. The front-end performances in LNA1 mode are 39.8 dB conversion gain, 2.2 dB NF, and -33.4 dBm IIP3 with 6.6 mW power consumption.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.34.3-34.3
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• 2008

Relative navigation system is presented using measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide real-time relative navigation results as well as absolute navigation results for two formation flying satellites separated about 1km in low earth orbit. To improve the performance, more accurate dynamic model and modified relative measurement model are developed. This modified method prevents non-linearity of the measurement model from degrading precision by applying linearization about the states from absolute navigation algorithm not about a priori states. Furthermore, absolute states are obtained using ion-free GRAPHIC pseudo-ranges and precise relative states are provided using double differential carrier-phase data based on Extended Kalman Filter. The software-based simulation is performed and achieved meter-level precision for absolute navigation and millimeter-level precision for relative navigation. The absolute and relative accuracies at steady state are about 0.77m and 4mm respectively (3D, r.m.s.). In addition, Integer ambiguity algorithm (LAMBDA method) improves simulation performances.

• Journal of the Korean Institute of Navigation
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• v.24 no.3
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• pp.133-140
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• 2000

The paper deals with the implementation of prototype Ship Simulator system (VRSS) by Virtual Reality techniques with Head Mounted Display (HMD) device. The prototype VRSS was consists of PC-based human sensors, object oriented operating system. In addition, two kinds of databases arranged from Head Related Transfer Functions and 3D object models were used to create 3D sea sound, and to construct virtual world, respectively. Using the prototype system, we carried out some simulation tests for the overtaking situation to prevent collisions at sea, and discussed on the usability of the system. As results from simulations, the prototype VRSS can provide multisensory and interactive display environment. The results gave rise to the user interaction with 3D objects that give realistic reproduction of navigational environments under a given scenario. Thus, we found that the prototype VRSS should be one of the next-generation ship simulation system.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2211-2216
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• 2005

This paper describes a novel navigation algorithm using a locomotion interface with two 6-DOF parallel robotic manipulators. The suggested novel navigation system can induce user's real walking and generate realistic visual feedback during navigation, using robotic manipulators. For realistic visual feedback, the virtual environment is designed with three components; 3D object modeler for buildings and terrains, scene manager and communication manager component. The walking velocity of the user is directly translated to VR actions for navigation. Finally, the functions of the RPC interface are utilized for each interaction mode. The suggested navigation system can allow a user to explore into various virtual terrains with real walking and realistic visual feedback.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.2
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• pp.91-99
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• 2013

An autonomous unmanned underwater vehicle is a type of marine self-propelled robot that executes some specific mission and returns to base on completion of the task. In order to successfully execute the requested operations, the vehicle must be guided by an effective navigation algorithm that enables it to avoid obstacles and follow the best path. Architectures and principles for intelligent dynamic systems are being developed, not only in the underwater arena but also in related areas where the work does not fully justify the name. The problem of increasing the capacity of systems management is highly relevant based on the development of new methods for dynamic analysis, pattern recognition, artificial intelligence, and adaptation. Among the large variety of navigation methods that presently exist, the dynamic window approach is worth noting. It was originally presented by Fox et al. and has been implemented in indoor office robots. In this paper, the dynamic window approach is applied to the marine world by developing and extending it to manipulate vehicles in 3D marine environments. This algorithm is provided to enable efficient avoidance of obstacles and attainment of targets. Experiments conducted using the algorithm in MATLAB indicate that it is an effective obstacle avoidance approach for marine vehicles.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.37-41
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• 2004

In this paper, a reflector type frequency doubler for local oscillator at 24GHz is designed and fabricated with ne71300-N MESFET. Optimum source and load impedances are decided through a multiharmonic load pull simulation technique. A conversion gain can be improved using the reflector and fundamental and third harmonics are well suppressed with open stub of $\lambda$/4 length Measured results show output power at 0dBm of input power is -3.776dBm, conversion gain 0.736dB, harmonic suppression 41.064dBc, respectively.

• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.113-118
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• 2002

In this paper, an internal GPS antenna for mobile phones is designed and fabricated. For the miniaturization of the antenna, high permittivity dielectric substrate((${\varepsilon}_r$=90) and small ground plane ($13mm{\times}13mm$) are used. To increase the receive gain, the antenna is composed with LNA(Low Noise Amplifier). Results of the manufactured antenna($13mm{\times}13mm{\times}8mm$) show that the maximum antenna gain is about 12 dBi, the axial ratio is less than 3 dB, and the current consumption of LNA is less than 4 mA.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.3
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• pp.221-228
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• 2021

The Korea Augmentation Satellite System (KASS) is a Korean Satellite Based Augmentation System (SBAS) that has been under development since 2014 with the goal of providing Approach Procedure with Vertical guidance (APV)-I Safety of Life (SoL) services. KASS Control Station (KCS) is a subsystem that controls and monitors KASS systems. It also serves to store data generated by KASS. KCS has now completed detailed design and implementation and verification is in progress. This paper presents verification procedures and verification items for KCS verification activities and presents management measures for defects occurring during the verification phase.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.2
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• pp.104-110
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• 2006

The 3D visualization of seafloor topography(ST) was realized to discuss the effective use by the 3D visualization of ST on the integrated navigation system(INS) for fishing boat. The software was to actually display the 3D visualization of ST using triangular irregular network, helical hyperspatial codes and stereo projection. The INS for fishing boat which applied the 3D visualization of ST will be utilized for safety voyage and the effective fishing work on the fishing ground.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.348-355
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• 2006

In this paper, frequency multipliers used S-band transponder of the KOMPSAT 3 are designed and fabricated. In the transponder, 108 times multiplier which generate 1st LO signal(2008.8MHz) is comprised of the X9 frequency multiplier, 1st X2 multiplier, 2nd X2 multiplier and the last stage of the X3 frequency multiplier. As results, output power of 8.17 dBm at 2008.8MHz, the harmonic suppression of -56.67dBc, the bandwidth of 14MHz were measured.