A cork(P50) was attached to protect the radome from severe aerodynamic heating due to increased flight speed and range of Anti-air missile system. A cork is excellent insulation material but is ablated during the flight. In order to calculate the temperature of radome attached with cork, the effect of cork being disappeared due to the ablation must be considered. In this study, the cork was divided into several thin layers and aerodynamic heating was added to the outermost layer in the analysis model. In the process of heat transfer analysis, the layer was deleted from the model when the temperature of the entire area of the layer reach the specific temperature(Tc). The cork ablation effect was simulated by repeating this process until all cork layers are deleted. By applying this analysis method, the temperature of the radome(Invar) measured in the flight test could be well simulated.

In this paper, abnormal noise and vibration occurring in the propulsion shaft system of a naval ship were measured, and the methods and procedures for the cause analysis based on the results were discussed. To investigate the cause, in this study, accelerometers were attached to the bearings supporting the shaft to measure the vibrations. The analysis revealed that the abnormal vibration on the port side was most strongly identified at the stern tube bearing, and it was confirmed that these vibrations exhibited ultra-high frequency(20,000 Hz ~) characteristics. Additionally, through DEMON analysis, it was confirmed that this characteristic appeared in synchronization with rotation of the shaft. In this paper, it is assumed that the cause of theses ultra-high frequency vibration has been generated by stress waves resulting from processes such as grinding, scratching and impact. Furthermore, directions for inspection of the stern tube bearing are proposed.

This paper presents a trajectory-based prototype-guided contrastive learning method for threat target classification and out-of-distribution(OOD) detection. To address softmax classifiers' overconfidence and feature dispersion issues, our approach employs a GRU encoder to represent variable-length trajectory data and a projection head to transform these features for contrastive learning. Dual contrastive losses are applied at both the encoder and projection head levels to tighten intra-class representations and separate inter-class features. Furthermore, a nearest prototype classification scheme intrinsically detects OOD samples without external data. Experimental results on simulated radar trajectory datasets demonstrate that our method significantly outperforms conventional softmax-based models, especially in distinguishing challenging OOD samples with dynamics similar to in-distribution data.

The rapid advancement of Artificial Intelligence(AI) has achieved remarkable progress in various fields such as image editing, audio generation, and video manipulation. However, it has also introduced new security threats, including deepfake speech and voice spoofing. This paper proposes a multi-feature deep learning based AI synthetic speech detection method capable of addressing these threats with high accuracy. The ASVspoof 2021 dataset's Logical Access(LA) and Deepfake(DF) data were used for training and testing. The proposed system utilizes two audio features, Mel-Spectrogram and MFCC(Mel-Frequency Cepstral Coefficients), to convert audio data into visual and sequential forms for training and inference. To demonstrate the superiority of the proposed method, a comparative analysis was conducted with various models such as CNN, BiLSTM, Transformer, and ensemble methods. Experimental results showed that the multi-feature fusion model outperformed single and ensemble models. The proposed multi-feature fusion model, which combines ConvNeXt-base and BiLSTM using a Late Fusion approach, achieved the highest performance with an accuracy of 98.44 %. The method proposed in this paper is expected to serve as a key technology in future AI deepfake synthetic speech detection systems.

This study proposes a real-time target localization method based on acoustic refraction correction to enhance the accuracy of mine avoidance sonar systems for safe submarine operations. Conventional mine avoidance sonars typically assume either straight-line or single eigen-ray propagation paths for estimating target locations, which can result in detection errors due to insufficient consideration of acoustic refraction effects in complex and varying oceanic sound speed profiles. To address these limitations, this paper introduces a real-time sonar imaging method employing multi-ray tracing based on transmission angles and detailed sound speed profiles, effectively correcting mismatches in target localization. Performance validation through simulations and ocean experiments involving variable depths and complex sound speed environments demonstrated significantly improved localization accuracy compared to traditional approaches, confirming the capability for accurate real-time target localization in multi-target and complex maritime scenarios.

This letter presents a generalized analytic solution for sinusoidal frequency estimation, extending Cedron's method from its original use of up to 3 frequency bins to consecutive frequency bins. We analyze the method's performance under various conditions, exploring the relationship between bin numbers, estimation accuracy, and computational complexity. Our findings suggest that increasing bin numbers doesn't always improve performance, with the best results observed using a limited number of bins under our experimental conditions.

In modern military operations, missiles that threaten aircraft have complex and lethal aspects. In order to effectively respond to these threats, a defense system utilizing advanced technologies is essential. MAW equipment can be operated with directional infrared jamming equipment and flares to respond to missile threats, thereby improving the survivability of aircraft. We conducted tests domestically to verify the detection impact of missile approach warning equipment using rotary-wing aircraft, and presented the test results under various test conditions.

All weapon systems mounted on aircraft, tank and submarine must be guaranteed to be stable against shock environment. Therefore, shock test of the onboard weapon system is essential to determine shock survivability. To implement a large sinusoidal shock waveform, the programmer(elastomer) with hyperelastic properties is used. In this paper, a mathematical model considering the damping and nonlinearity of the hyperelastic programmer is suggested. The parameters of the proposed model are numerically obtained using test data from the horizontal shock test machine. Then the dynamic characteristics of the hyperelastic programmer are gained from the model in which parameters are obtained.

This study explores condensation in a serpentine condenser of multi-fuction radar cooling device. The numerical model using Volume-of-Fluid(VOF) method is developed to compute the flow field considering phase change heat transfer. The effects of inlet velocities and gravitational acceleration are examined. The condensation heat transfer coefficients at upper and lower surface of each channel are then calculated. The results show that the differences of the condensation heat transfer coefficients between upper and lower surface are noticeable except for the first channel. These results are shown to be closely related to the liquid fraction distributions in a U-bend tube. While the flow regimes in the channels are depending on the presence of gravity, the flow regimes in the U-bend tube and the trends of the condensation heat transfer coefficients on each channel are regardless of the presence of gravity.

Recently, ground-based multi-function radars are being developed in the form of SDR(Software Defined Radar) that can implement various performances based on similar H/W architecture. Accordingly, the H/W structure of the internal antenna device constituting the radar is also being standardized. In this paper, we propose a modular power supply equipment that can flexibly respond to changes in the power requirements of the internal antenna device based on scalability. This can simplify the circuit structure and realize device miniaturization, and when applied in parallel to multiple radar systems, it is expected to reduce the resources required for development and make maintenance much easier. The technical feasibility and effectiveness of the system suitability of the proposed power supply equipment were verified through electrical performance tests, electromagnetic compatibility tests, and environmental tests.

This study focuses on the design of a drive system for the stabilization control of a Remotely Controlled Weapon System(RCWS). First, the 3-degree-of-freedom(3-DOF) motion equations of a two-axis gimbal-structured RCWS are derived. The final motion equations are established by applying structural constraints. Second, the motor torque and gear ratio are designed. The motor torque is calculated by separating the friction torque from the acceleration torque. The gear ratio is determined based on the ratio of the moment of inertia between the motor rotor and the structural load, considering the torque transmission efficiency. Third, a stabilization control algorithm using a dual feedback loop is developed. The inner loop utilizes angular rates measured by an encoder, while the outer loop uses angular velocities measured by an Inertial Measurement Unit(IMU). Finally, the performance of the RCWS drive system is evaluated in terms of stabilization accuracy under RRC-9 course disturbances. It is concluded that this research contributes to the development of drive systems and stabilization control techniques for RCWS and turrets used in tanks and armored vehicles.

This study proposes a system design for maintaining a stable laser aiming point in a vibrational environment. The proposed system utilizes a Fast Steering Mirror(FSM) to precisely control the laser beam, correcting the aiming point in real time through image tracking and laser center detection algorithms. Experiments were conducted in an environment with random vibrations applied using a 6-axis simulator, employing OpenCV's ViTTracker and the ISO 11146 standard-based laser center detection technique. The results demonstrate that the proposed system exhibits robust performance against vibrations, maintaining an average aiming point error of 0.1 mm or less.

The recent war between Russia and Ukraine has raised interest and the need for active protection systems for combat vehicles. Combat vehicles are protected by armor, but the development of threats to disable them is accelerating further. In particular, questions are being raised about the operational effectiveness of armored combat vehicles, which have recently been severely damaged by missiles and drone attacks in combat settings. To overcome this reality, we are reviewing the application of hard-kill and soft-kill active protection systems to apply a multi-layer protection system for next-generation combat vehicles. Improved survivability increases combat duration and ultimately affects combat power. In this paper, we investigate and analyze various threats to destroy combat vehicles on the battlefield, analyze the minimum range and appropriate response time for operation of the threats based on an operation concept that takes into account recent combat patterns, and establish a response concept for active protection technology based on this concepts. To this end, we propose an engagement algorithm that analyzes the threat level based on the flight information of the identified threat, determines the threat priority, and assigns a response order of countermeasures.

The Warrior Platform is an ambitious personal combat system improvement project that the Army is pursuing with the goal of enhancing the combat power of combatants as well as improving their defense and survivability. It is being developed with the goal of integrating combat equipment, combat gear, and combat clothing into a single combat system called the Warrior Platform to maximize the combat power of each combatant and actively respond to changes in the future battlefield environment. Through this, the purpose is to supplement the power gap caused by the reduction in manpower resources by improving the eliteness and combat efficiency of each combatant. In this study, the combat effectiveness of the mission equipment of the integrated personal combat system system compared to the existing personal combat equipment was analyzed. To this end, the combat efficiency weights through pairwise comparison with existing individual combat equipment were derived using the AHP technique, and an approach was presented on how to reflect this as a combat power index of the ground weapon effectiveness analysis model and simulate it. Unlike the effectiveness analysis of a specific weapon system, this study presents an objective and quantitative method on how to analyze the impact of changes in mission equipment that individual combatants must have on combat effectiveness, and it is judged that it can be utilized to verify the effectiveness for the future power-up of individual combat systems.

Recently, in the defense sector, there has been much interest in acquiring weapon systems that incorporate new technologies of the 4th industrial revolution, such as artificially intelligence. This study is about the technological convergence and diffusion of patents related to AI and military technology. We extracted domestic defense AI patents including both military and AI technologies applied from 2015 to 2023, then their cited patents extracted. The analysis shows that the Defense research institute and some defense industry companies are playing a key role, but Defense AI patent applications in the civilian fields was more than that in the military fields. In addition, the convergence of AI and military technology was expanding both scope and field. The significance of this study is that it confirmed the convergence and diffusion of defense AI technology and temporal changes, and also suggested the direction of defense R&D for the spin-on of new civilian technologies.