• Journal of Positioning, Navigation, and Timing
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• v.7 no.2
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• pp.73-90
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• 2018

Various navigation systems are integrated with the Global Navigation Satellite System (GNSS) to improve navigation performance so that continuous navigation information can be obtained even when navigation performance is degraded or navigation is not available due to the outage of GNSS. Time and cost can be reduced by evaluating performance of the integrated navigation system through Modeling and Simulation (M&S) software prior to the deployment of the integrated navigation system. The measurements of the navigation system should be generated to evaluate performance through of the navigation system M&S software. This paper proposes a method of designing a navigation environment generation module in M&S software of the integrated navigation system. To show applicability of the proposed method to M&S software design of the integrated navigation system, functions are verified through MATLAB. And then visual C++ based M&S software for the integrated navigation system is implemented to check the operation of the navigation environment generation module. The reference trajectory is generated and true measurements of Global Positioning System (GPS), Korea Positioning System (KPS), and enhanced Long range navigation (eLoran) are generated from the reference trajectory. The navigation results obtained from the true measurements are compared with the reference trajectories. The results show that the measurements generated using the design generation module by the proposed method are valid and the navigation environment generation module can be applied to M&S software of the integrated navigation system.

• Korean Journal of Optics and Photonics
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• v.25 no.5
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• pp.245-253
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• 2014

We report a realistic field-performance simulation for a new MWIR camera. It is designed for early detection of missile plumes over a distance range of a few hundred kilometers. Both imaging and radiometric performance of the camera are studied by using real-scale integrated ray tracing, including targets, atmosphere, and background scene models. The simulation results demonstrate that the camera would satisfy the imaging and radiometric performance requirements for field operation.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.131-137
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• 2019

The operation of the precision-guided missiles with seekers is becoming more and more dominant since the modern wars became geographically localized like anti-terror campaigns and civil wars. Imaging seekers are relatively low-price and applicable to various operational conditions. The image tracker, however, requires highly advanced method for the target tracking under harsh missile flight condition. Missile roll can reduce the tracking performance since it introduces big differences in imagery. The missile roll is inevitable because of the disturbance and flight control error. Consequently, the errors of the subsystems should be under control for the stable performance of the tracker and the whole system. But the performance prediction by some simple metric is almost impossible since the target signature and the tracker are highly nonlinear. We established M&S tool for a precision-guided missile with imaging seeker and analyzed the roll effects to tracking and system performance. Furthermore, we defined the specification of missile subsystems through error analysis to guarantee system performance.

• Journal of the Korea Society for Simulation
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• v.28 no.1
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• pp.81-91
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• 2019

The ROK military uses Performance Based Logistics(PBL) as one of the ways to utilize civilian resources and advanced techniques. However, the Korean PBL is mainly focused on purchasing and repairing parts, which is not contributing to the improvement of the availability of overall system. The objective of this study is to suggest the methodology to evaluate the PBL metrics using the simulation and meta model. A meta model is a regression model to analyze the effect of the PBL through simulating various scenarios with performance metrics. As a result, if the PBL is limited to the part level, the performance has little influence on the availability of overall system. In addition, analysis using the meta model shows that it cannot achieve the performance targets when the same metrics are applied to various items without considering the characteristics of the applied items. Therefore, in order to improve availability, PBL coverage should be extended to a system level that includes key components that have a large impact on availability. If multiple items are included in the PBL coverage, the metrics should be applied differently, taking into account the characteristics of each item.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.1-11
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• 2020

In this study, study on the internal ballistic analysis method for single-chamber dual-thrust rocket motors meeting a dual-thrust profile requirement by tailoring the grain burning area is presented. The analysis method, which can acquire variables required for the performance prediction, considering gradual change of burning rate correction factor and specific impulse in the transition phase, is proposed. Improvements compared to the analysis method in the previous study, which do not consider change in the transition phase, are verified through comparison between the newly proposed method and the method in the previous study. Internal ballistic variables are obtained for four different ground firing test conditions using the proposed method, and the performance prediction for each condition is conducted using these variables. These prediction results and the ground test data are in good agreement, so it is confirmed that the performance prediction of dual-thrust motors with same design geometries based on the proposed analysis method is available.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.4
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• pp.45-57
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• 2022

The Ministry of National Defense of the Republic of Korea is showing a lot of interest in net zero-energy buildings (NZEBs) to reduce energy consumption of military facilities and to promote green growth policy in military sector. The application of building passive technologies and renewable energies is essential to achieving NZEBs. This paper analyzed energy performance and energy cost on the conventional heating and cooling system (baseline scenario) and three different alternative scenarios (ALT 1, ALT 2 and ALT 3) applied in a hypothetical military building. A building modeling and simulation software (DesignBuilder V6.1) with EnergyPlus calculation engine was used to calculate the energy consumption for each scenario. Overall, when the GSHPs are applied to both space airconditioning and domestic hot water (DHW) production, Alt-2 and Alt-3, the amount of energy consumption for target building can be greatly reduced. In addition, when the building envelope performance is increased like Alt-3, the energy consumption can be further reduced. The annual energy cost analysis showed that the baseline was approximately 161 million KRW, while Alt-3 was approximately 33 million KRW. Therefore, it was analyzed that the initial construction cost increase could be recovered within about 6.7 years for ALT 3. The results of this study can help decision-makers to determine the optimal strategy for implementing GSHP systems in military buildings through energy performance and initial construction cost assessment.

• Journal of Mechanical Science and Technology
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• v.16 no.8
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.123-130
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• 2015

In this study, a carrier smoothed global positioning system / dead reckoning (CSGPS/DR) integrated system for high-precision trajectory estimation for the purpose of vehicle navigation was proposed. Existing code-based GPS has a low position accuracy, and carrier-phase differential global positioning system (CPDGPS) has a long waiting time for high-precision positioning and has a problem of high cost due to the establishment of infrastructure. To resolve this, the continuity of a trajectory was guaranteed by integrating CSGPS and DR. The results of the experiment indicated that the trajectory precision of the code-based GPS showed an error performance of more than 30cm, while that of the CSGPS/DR integrated system showed an error performance of less than 10cm. Based on this, it was found that the trajectory precision of the proposed CSGPS/DR integrated system is superior to that of the code-based GPS.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.6 s.312
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• pp.105-112
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• 2006

To improve the performance of identification for radars in an ES(Electronic warfare Support) system, it is necessary to estimate scan characteristics as well as the basic identification parameters such as frequency, pulse repetition interval and pulse width of radars. This paper presents the method of estimating the scan period and the scan beam width of circular scanning radars. The proposed method estimates the scan period using the quality of the autocorrelation of a periodic signal. And, it estimates the scan beam width using the linear interpolation and the proposed method of estimating the scan period. Simulation results are presented to show the performance of the proposed method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.3
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• pp.1-8
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• 2001

In the DS/CDMA mobile communication systems, the parallel interference canceller is used in order to reduce the multiple access interference and the multipath fading. It is needed the accurate interference estimate in the multistage parallel cancellation. In this paper, the adaptive cancellation method and the new tentative decision device arc proposed and the performance is analyzed. The adaptive cancellation method uses the normalized least mean square(NLMS) algorithm to calculate the weight adaptively, and new tentative decision device uses the hyperbolic tangent decision with null zone. Computer simulation shows that the proposed scheme has the improved performance and the number of user is increased 48% compared with the conventional receiver.