• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.3
• /
• pp.288-294
• /
• 2018

Recently, as the speed and performance of the launcher and the missile have been improved, it is necessary to consider the acoustic load of launching and flight in initial design step. In this paper, an experimental study on acoustic absorption and transmission characteristics of aluminium vs. sandwich composite structures were conducted. The overall noise reduction was evaluated by performing an acoustic test in the reverberation room, and the acoustic absorption and transmission loss of the structures were analyzed by conducting the sound absorption test inside the structure.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.8
• /
• pp.2020-2030
• /
• 1999

Data acquired about 53 gigabyte per a naval vessel is massive, expensive and impossible to be retested in a underwater acoustic measurement. So, it is required to manage systematically. In this paper, we mention MUADS (Massive Underwater Acoustic Database System) that was developed to store a long time, manage systematically and supply raw data and analyzed data. we analyze client/server performance based on 6003 input data individually in our MUADS that Unix server having a massive DC-jukebox and Windows clients.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.10
• /
• pp.4080-4097
• /
• 2020

In recent years, convolutional neural network (CNN) has become the primary method for face detection. But its shortcomings are obvious, such as expensive calculation, heavy model, etc. This makes CNN difficult to use on the mobile devices which have limited computing and storage capabilities. Therefore, the design of lightweight CNN for face detection is becoming more and more important with the popularity of smartphones and mobile Internet. Based on the CPU real-time face detector FaceBoxes, we propose a multi-task lightweight face detector, which has low computing cost and higher detection precision. First, to improve the detection capability, the squeeze and excitation modules are used to extract attention between channels. Then, the textual and semantic information are extracted by shallow networks and deep networks respectively to get rich features. Finally, the landmark detection module is used to improve the detection performance for small faces and provide landmark data for face alignment. Experiments on AFW, FDDB, PASCAL, and WIDER FACE datasets show that our algorithm has achieved significant improvement in the mean average precision. Especially, on the WIDER FACE hard validation set, our algorithm outperforms the mean average precision of FaceBoxes by 7.2%. For VGA-resolution images, the running speed of our algorithm can reach 23FPS on a CPU device.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.11
• /
• pp.1323-1326
• /
• 2012

In military applications, many radar systems are simultaneously operated at a close range. In particular, the frequency allocation must be executed for operating the homogeneous radar systems at the same time. As many radar systems are simultaneously operated with overlapping frequency bands, interference between systems inevitably occurs. Because interference can degrade radar performance, suppression of interference is a critical issue in radar systems. In this letter, we analyze the interference between two FMCW radars. In addition, time synchronization method between radars using mutual interference is proposed. Experiments are carried out to validate the proposed method. The results demonstrate that the proposed method is suitable for real radar systems.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.7 no.2 s.17
• /
• pp.100-108
• /
• 2004

Nitramine-polymer composites suffer from a problem known as dewetting. Dewetting adversely affects the performance and the sensitivity characteristics of an explosive composition. Voids, which are generated between explosive particles and binder on dewetting, act as initiation sites. For a PBXs as well as propellants, where good adhesion and mechanical properties are of great importance, dewetting therefore must be prevented by strong adhesion between the filler and the binder. The surface energy of materials is measured by Wilhelmy plate and wicking method. The interfacial energy between the filler and the binder is calculated from the disperse phase and the polar phase of surface energy. Time dependent compressive properties of composite explosives have been determined by stress-strain curves obtained at different strain rates and temperatures. The interfacial state of the PBX was observed through SEM. It was found from the result that the interface between the explosive and the binder becomes better adhesion with decreasing interfacial tension and increasing work of adhesion. The result clearly shows that the castable PBX has good adhesion more than the pressable PBX.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.462-464
• /
• 2015

Since the first Aegis Cruiser USS Ticonderoga was constructed, Arleigh Burke class destroyers are being mass constructed as U.S. Naval capital surface ships and consistently improved the performance. In recent years, the newest aegis combat system, Baseline 9, was deployed. Aegis BMD, aegis ships which have BMD capability, is participated BMDS(Ballistic Missile Defense System) as a sea based BMD. And AN/SPY-1D will be replaced by AMDR(Air & Missile Defense Radar), advanced anti-air radar system to defend effectively against increased ballistic missiles threat from DDG-51 Flight III. In this paper, development status and technical characteristics of each type of aegis ships are researched and characteristics of AMDR are surveyed and described.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.4C
• /
• pp.441-447
• /
• 2004

Information security simulator is required for the study on the cyber intrusion and defense as information security has been increasingly popular Until now, the main purposes of information security simulation are security estimation of small network as well as performance analysis of information protection systems. However, network simulators that can simulate attacks in a huge network are in needs since large scale internet attacks are very common in these days. In this paper we proposed a simulator design and its implementation details. Our simulator is implemented by expanding the SSFNet program to the client-sewer architecture. A cyber attack scenario used in our simulator is composed by the advanced attack tree model. We analyzed the simulation results to show the correctness of our network defense simulator.

• Journal of Communications and Networks
• /
• v.17 no.6
• /
• pp.558-567
• /
• 2015

In recent years, we have seen a proliferation of mobile-network-enabled smart objects, such as smart-phones and smart-watches, that form a cyber-physical integrated network to connect the cyber and physical worlds through the capabilities of sensing, communicating, and computing. Discovery of the relationship between smart objects is a critical and nontrivial task in cyber-physical integrated network applications. Aiming to find the most stable relationship in the heterogeneous and dynamic cyber-physical network, we propose a distributed and efficient relationship-discovery algorithm, called dynamically maximizing remaining unchanged time with minimum connected dominant set (DMRUT-MCDS) for constructing a backbone with the smallest scale infrastructure. In our proposed algorithm, the impact of the duration of the relationship is considered in order to balance the size and sustain time of the infrastructure. The performance of our algorithm is studied through extensive simulations and the results show that DMRUT-MCDS performs well in different distribution networks.

• Journal of the military operations research society of Korea
• /
• v.28 no.1
• /
• pp.115-135
• /
• 2002

The limits of current DN(Defense networks), private and closed network, become to reality; for Example, high expense of construction and maintenance of networks, restriction of new subscribers on DN. Therefore, a network using web environment that reflect fast development of If and IS(Information Security) technology is demanded for MND. Meeting the requirement of reliable IS system and extension and improvement of DN using common network, we can reduce the expense to extend, maintain, repair DN, form the environment that makes military business cooperate better with civil company and government agency, advance implementing Defense computing and networking service for field small size units that was a exception of Defense digitalization. But it is essential to construct DN based on common network that there are security requisites; confidentiality, integrity, availability, efficiency, log, backup, restoration, that have to be realized at demanding level for IS. This thesis suggested four measurements; replacement DN with common network to resolve the requirements of building new network and improvement of performance for private DN, linkage with common network for new requirement, distribution of traffic using common network, configuration of DN using Internet and Proposed a refinement of IS management organization to treat security threat of common network flexibly, and LAN IS standard model of DN based on the web environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.7
• /
• pp.848-851
• /
• 2012

As many radar systems are simultaneously operated with overlapping frequency bands, interference between systems inevitably occurs. Because interference can degrade radar performance, suppression of interference is a critical issue in radar systems. In this letter, a new interference detection and suppression method using a short-time Fourier transform and an adaptive notch filter is proposed. An experiment is carried out to validate the proposed method and the results demonstrate that the proposed method is suitable for application in real FMCW radars.