• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.463-472
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• 2005

In this paper, the dynamic model development for interplanetary navigation has been discussed. The Cowell method for special perturbation theories was employed to develop an interplanetary trajectory propagator including the perturbations due to geopotential, the Earth's dynamic polar motion, the gravity of the Sun, the Moon and the other planets in the solar system, the relativistic effect of the Sun, solar radiation pressure, and atmospheric drag. The equations of motion in dynamic model were numerically integrated using Adams-Cowell 11th order predictor-corrector method. To compare the influences of each perturbation, trajectory propagation was performed using initial transfer orbit elements of the Mars Express mission launched in 2003, because it can be the criterion to choose proper perturbation models for navigation upon required accuracy. To investigate the performance of dynamic model developed, it was tested whether the spacecraft can reach the Mars. The interplanetary navigation tool developed in this study demonstrated the spacecraft entering the Mars SOI(Sphere of Influence) and its velocity .elative to the Mars was less than the escape velocity of the Mars, hence, the spacecraft can arrive at the target planet. The obtained results were also verified by using the AGI Satellite Tool Kit. It is concluded that the developed program is suitable for supporting interplanetary spacecraft mission for a future Korean Mars mission.

• Archives of design research
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• v.16 no.4
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• pp.25-36
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• 2003

The navigation in 3D virtual space is a procedure which must be carefully established in advance with understanding of a complicate perception process. Although current various desktop softwares are suppling developers with easier production circumstances in accordance with popularization era of interactive 3D media it is true that previous systematic conceptual study has been performed exclusively at specific institutions. Therefore, based upon the examples of virtual reality research reported by universities and companies core concepts giving the background for navigation realization and direct/indirect factors supporting substantial realization were analyzed and discussed in this paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.627-632
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• 2007

Dual quaternion is efficient methodology to express rotation and translation of the vehicle's movements in the unified frame work. Recently, a strapdown inertial navigation algorithm based on dual quaternion was introduced. By comparing and analyzing the classical and dual-quaternion algorithms, this paper proposes a new strapdown inertial navigation algorithm that maintains the accuracy benefit of the dual-quaternion algorithm with considerable computational reduction. Simulation results show the efficiency of the proposed hybrid strapdown navigation algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.998-1001
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• 2009

This paper shows that the conventional proportional navigation guidance(PNG) law with a constant navigation gain is an optimal solution strictly also when the velocity is varying during engagement. Especially, PNG with navigation constant, 3, is an optimal solution minimizing a closing velocity weighted induced-drag. While most of previous studies on optimality of PNG were relied on the linear formulation and the constant speed assumption, this study presents more general analysis results on optimality of PNG based on the nonlinear formulation and the time-varying velocity assumption.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.565-573
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• 2017

This paper presents a multistage in-flight alignment (MIFA) method for a strapdown inertial navigation system (SDINS) suitable for moving vehicles with no initial attitude references. A SDINS mounted on a moving vehicle frequently loses attitude information for many reasons, and it makes solving navigation equations impossible because the true motion is coupled with an undefined vehicle attitude. To determine the attitude in such a situation, MIFA consists of three stages: a coarse horizontal attitude, coarse heading, and fine attitude with adaptive Kalman navigation filter (AKNF) in order. In the coarse horizontal alignment, the pitch and roll are coarsely estimated from the second order damping loop with an input of acceleration differences between the SDINS and GPS. To enhance estimation accuracy, the acceleration is smoothed by a scalar filter to reflect the true dynamics of a vehicle, and the effects of the scalar filter gains are analyzed. Then the coarse heading is determined from the GPS tracking angle and yaw increment of the SDINS. The attitude from these two stages is fed back to the initial values of the AKNF. To reduce the estimated bias errors of inertial sensors, special emphasis is given to the timing synchronization effects for the measurement of AKNF. With various real flight tests using an UH60 helicopter, it is proved that MIFA provides a dramatic position error improvement compared to the conventional gyro compass alignment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.274-282
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• 2019

Vision-based navigation of unmaned aerial vehicle is a significant technology that can reinforce the vulnerability of the widely used GPS/INS integrated navigation system. However, the existing image matching algorithms are not suitable for matching the aerial image with the database. For the reason, this paper proposes particle filters using Gaussian mixture models to deal with matching between aerial image and database for vision-based navigation. The particle filters estimate the position of the aircraft by comparing the correspondences of aerial image and database under the assumption of Gaussian mixture model. Finally, Monte Carlo simulation is presented to demonstrate performance of the proposed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.1
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• pp.41-48
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• 2019

This paper deals with a method of aligning an aircraft fuselage and an inertial navigation sensor using three-dimensional coordinates obtained by an optical method. In order to verify the feasibility, we introduce the method to accurately align the coordinate system of the inertial navigation sensor and the aircraft reference coordinate system. It is verified through simulation that reflects the error level of the measuring device. In addition, optimization method based alignment algorithm is proposed for connection between optical sensor and inertial navigation sensor.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.191-200
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• 2000

Recently, NORAD reported that only 6% of the total space objects cataloged in the table as above 10cm objects were being operated for the space missions and the others were just non-operated objects, such as rocket body, useless satellites which were finished their missions, and other fragments of space debris. A major contributor to the orbital debris background has been object breakup. Breakups generally are caused by explosions and collisions. Several international research groups and big countries' governments are trying to develop advanced technology for de-orbiting and to design new future satellites' modeling. The future need to be considered continuously that kind of technology and designing to preserve space and global environmental safety and to maintain welfare of mankind forever.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.663-668
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• 2006

This thesis tries to evaluate the economic benefit of space chartering in comparison with time chartering with respect to mega container ships. For this it reviews the method of obtaining ship's carrying capacity such as time chartering and space chartering. Based on this, it tries to make comparison between the time chartering and space chartering on economic base. Finally, it suggest the economic benefit of space chartering with direction for further study.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.47-51
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• 2006

Among Solar activities' events, the geomagnetic storms are believed to cause the largest atmospheric effects. The geomagnetic storm is a complex process of solar wind/magnetospheric origin. It is well known to affect severely on the ionosphere. However, this effect of this complex process will maybe act at various altitudes in the atmosphere, even including the lower layer and the neutral middle atmosphere, particularly the stratosphere. Nowadays, the GPS-derived ZTD (zenith tropospheric delay) can be transformed into the precipitable water vapor (PWV) through a function relation, and further has been widely used in meteorology, especially in improving the precision of Numerical Weather Prediction (NWP) models. However, such geomagnetic effects on the atmosphere are ignored in GPS meteorology applications. In this paper, we will investigate the geomagnetic storms' effects on the middle atmosphere and troposphere (0-100km) by GPS observations and other data. It has found that geomagnetic storms' effect on the atmosphere also appears in the troposphere, but the mechanism to interpret correlations in the troposphere need be further studied.