• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.1
• /
• pp.81-87
• /
• 2012

This paper establishes a modeling and simulation procedure for structural response and reliability of a cylindrical array sensor on submarines under the shock generated by underwater explosion. The structural reliability of SONAR is important because the submarine could get out of combat ability by the structural damage of the SONAR upon explosion. A cylindrical array sensor was first modeled using the finite element method. Modal analysis was then performed for the check of the reliability of the modeling. The shock resistance simulations were performed for the responses to the structural shock waves and for the responses to the directly applied underwater shock waves, according to BV-043 and MIL-STD-901D, respectively. The stresses of the structure were evaluated with von-Mises scheme. Vulnerable regions were exposed through mapping the maximum stress to the structural model. Maximum stress of the SONAR was compared with the yield stress of the material to examine the structural reliability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.4
• /
• pp.1822-1829
• /
• 2012

In this research, we developed the Information Circulation Model(ICM) by modifying and supplementing Information Process Model(IPM) in DNS. This ICM is used to simulate some combat situations that could not be considered with the existing DNS. We showed that this improved ICM can be applied to simulation and analysis of a variety of interests compared with IPM in DNS. We expect this study could be a basic research for further development of C4ISR effectiveness analysis in our national defense community.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.5A
• /
• pp.501-508
• /
• 2006

Orthogonal frequency division multiplexing-code division multiplexing access(OFDM-CDMA) systems without guard interval can enhance the bandwidth performance more efficiently than the systems with guard interval. In this paper, a new technique for an OFDM-CDMA system without guard interval, which can eliminate inter-symbol interference(ISI) and inter-channel interference(ICI), is presented. The proposed algorithm is a new demodulation technique, based on the Pseudo-Decorrelator, and it is named PD algorithm. Simulation results show that the PD algorithm can combat ISI and ICI efficiently for an OFDM-CDMA system without guard interval. The BER performance of the PD algorithm is much better than that of a conventional OFDM-CDMA system without guard interval.

• Water Engineering Research
• /
• v.6 no.1
• /
• pp.17-30
• /
• 2005

The bed evolution of the stretch of the River Rhine between km-812.5 and km-821.5 is characterised by general bed degradation as a result of the river training works and dredging activities of the last two centuries. The degradation of the river bed affects the water levels, and so the navigation conditions. To combat the erosion of the river bed with the aim to keep up the shipping traffic and to avoid the ecological system damages due to water level reductions, sand-gravel-mixtures were added to the river (so called artificial grain feeding activities). This paper presents the results of an application of a graded sediment transport model in order to study morpholodynamical characteristics due to artificial grain feeding activities in the river stretch. The finite element code TELEMAC2D was used for flow calculation by solving the 2D shallow water equation on non-structured grids. The sediment transport module SISYPHE has been developed for graded sediment transport using a multiple layer model. The needs to apply such graded sediment transport approaches to study morphological processes in the domain are discussed. The calculations have been carried out for the case of middle water flow and different size-fraction distributions. The results show that the grain feeding process could be well simulated by the model.

• Journal of Institute of Control, Robotics and Systems
• /
• v.12 no.7
• /
• pp.713-718
• /
• 2006

Supersonic jet fighter aircraft have several different weapon loading configuration to support air-to-air combat and air-to-ground delivery of weapon modes. Especially, asymmetric loading configurations could result in decreased handling qualities for the pilot maneuvering of the aircraft. The design of the T-50 lateral-directional roll axis control laws change from beta-betadot feedback structure to simple roll rate feedback structure and gains such as F-16 in order to improve roll-off phenomena during pitch maneuver in asymmetric loading configuration. Consequently, it is found that the improved control law decreases the roll-off phenomenon in lateral axes during pitch maneuver, but initial roll response is very fast and wing pitching moment is increased. In this paper, we propose the lateral control law blending between beta-betadot and simple roll rate feedback system in order to decreases the roll-off phenomenon in lateral axes during pitch maneuver without degrading of roll performance.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.8
• /
• pp.148-155
• /
• 2015

The Levenberg-Marquardt method is a well known solution about the least square problem. However, in a Target Motion Analysis(TMA) application most of researches have used the Gauss-Newton method as a batch estimator, which of inverse matrix calculation may causes instability problem. In this paper, Levenberg-Marquardt method is applied to TMA problem to prevent its divergence. In experiment, its performance is compared with Gauss-Newton in domain of range, course and speed. Monte Carlo simulation reveals the convergence time and reliability of the TMA based on Levenberg-Marquardt.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.4
• /
• pp.639-647
• /
• 2011

In this paper, we have designed the Anti-Aircraft Artillery(AAA) model for the surface-to-air virtual engagement. The AAA model for the virtual combat simulation needs to detect the present target and estimate the target flight trajectory to find the aiming point. To find collision point of projectile fired from the artillery with the moving air target, we have presented the estimating technique for artillery aiming point. And we have analyzed the target probability of kill using Calton Hit function. Anti-air threat envelops are presented when the target velocity, position and the arrangement of four AAA are varying. Then we have compared the analyzed result using developed model with AEM model of MSA program.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.5
• /
• pp.2067-2080
• /
• 2016

Cooperative spectrum sensing (CSS) for vacant licensed bands is one of the key techniques in cognitive radio networks. Currently, sequential probability ratio test scheme (SPRT) is considered as a powerful soft decision approach to improve the sensing result for CSS. However, SPRT assumes all secondary users (SU) are honest, and thus offering opportunities for malicious SUs to launch the spectrum sensing data falsification attack (SSDF attack). To combat such misbehaved behaviors, recent efforts have been made to trust mechanism. In this paper, we argue that powering SPRT with traditional trust mechanism is not enough. Dynamic SSDF attackers can maintain high trust in an alternant process of submitting honest or false sensing data, resulting in difficultly detecting them. Noting that the trust value of dymamic SSDF attackers behave highly volatile, a novel trusted SPRT scheme (VSPRT) based on volatility decay analysis is proposed in this paper to mitigate the harmful effect of dynamic SSDF attackers in the process of the soft-decision data fusion, and thus improving the accuracy of the final sensing result. Simulation results show that the VSPRT scheme outperforms the conventional SPRT schemes.

• Journal of Korea Game Society
• /
• v.17 no.6
• /
• pp.165-172
• /
• 2017

Some duplicate processes are happen in developing games under the diverse platforms. Implementing functions. like processing and managing data, in every platforms have an influence on game development. In this paper, we propose a multi-platform server framework that can simulate combat games such as one server on any platform. It was designed to be easy to debug using a protocol consisting of attribute-value pairs by the JSON data format. Since it is independent of the programming language, it has the advantage of being able to communicate with various languages. The server proposes a model that can easily upgrade the structure or the specification using the Amazon web server.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.4A
• /
• pp.303-311
• /
• 2011

In this paper, we propose the adaptive multibeamforming algorithm to remove the same subcarrier interference and multipath signals in the MIMO(Multi-Input Multi-Out)-OFDMA (Orthogonal Frequency Division Multiplexing Access)system allocated the same subcarrier partially in order to improve spectrum efficiency. In addition to removing the interference, we can get diversity gain and combat the detriment of the performance according to time delay by the proposed approach. BER performance improvement and combating the delay spread detrimental effects of the proposed approach is investigated through computer simulation by applying it to MIMO-OFDMA.