• Nano
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• 제13권11호
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• pp.1850126.1-1850126.10
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• 2018

Flexible strain sensors, as the core member of the family of smart electronic devices, along with reasonable sensing range and sensitivity plus low cost, have rose a huge consumer market and also immense interests in fundamental studies and technological applications, especially in the field of biomimetic robots movement detection and human health condition monitoring. In this paper, we propose a new flexible strain sensor based on thick CVD graphene film and its low-cost fabrication strategy by using the commercial adhesive tape as flexible substrate. The tensile tests in a strain range of ~30% were implemented, and a gage factor of 30 was achieved under high strain condition. The optical microscopic observation with different strains showed the evolution of cracks in graphene film. Together with commonly used platelet overlap theory and percolation network theory for sensor resistance modeling, we established an overlap destructive resistance model to analyze the sensing mechanism of our devices, which fitted the experimental data very well. The finding of difference of fitting parameters in small and large strain ranges revealed the multiple stage feature of graphene crack evolution. The resistance fallback phenomenon due to the viscoelasticity of flexible substrate was analyzed. Our flexible strain sensor with low cost and simple fabrication process exhibits great potential for commercial applications.

• 경영과학
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• 제26권3호
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• pp.157-167
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• 2009

Technology transition from defense technology to weapon system is an important process for defense acquisition program. Many countries such as USA, UK, Australia and Republic of Korea use technology readiness level (TRL) as a tool for technology transition by identifying critical technology elements (CTEs) and assessing the technology maturity. In this paper we review a transition process for the defense acquisition. Then we suggest a method to evaluate system's TRL using each component TRL and integration readiness level (IRL) between each technologies. We apply the method to an ACTD project. A result show that technology maturity is influenced by integration between technologies.

• 한국군사과학기술학회지
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• 제17권6호
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• pp.810-820
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• 2014

Recently many studies of Radar systems mounted on ground vehicles for autonomous driving, SLAM (Simultaneous localization and mapping) and collision avoidance are reported. In near field, several hits per an object are generated after signal processing of Radar data. Hence, clustering is an essential technique to estimate their shapes and positions precisely. This paper proposes a method of grouping hits in range-doppler domains into clusters which represent each object, according to the pre-defined rules. The rules are based on the perceptual cues to separate hits by object. The morphological connectedness between hits and the characteristics of SNR distribution of hits are adopted as the perceptual cues for clustering. In various simulations for the performance assessment, the proposed method yielded more effective performance than other techniques.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권10호
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• pp.2731-2749
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• 2012

Sybil attack has been proved effective in mitigating the P2P botnet, but the impacts of some important parameters were not studied, and no model to estimate the effectiveness was proposed. In this paper, taking Kademlia-based botnets as the example, the model which has the upper and lower bound to estimate the mitigating performance of the Sybil attack is proposed. Through simulation, how three important factors affect the performance of the Sybil attack is analyzed, which is proved consistent with the model. The simulation results not only confirm that for P2P botnets in large scale, the Sybil attack is an effective countermeasure, but also imply that the model can give suggestions for the deployment of Sybil nodes to get the ideal performance in mitigating the P2P botnet.

• Structural Engineering and Mechanics
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• 제54권6호
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• pp.1045-1059
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• 2015

Form-finding for cable-membrane structures is a delicate operation. During the last decades, the force density method (FDM) was considered to be an efficient method to address the problem. Many researchers were devoted to improving this method and proposed many methods such as natural force density method (NFDM), improved nonlinear force density method (INFDM), et al. In this paper, a modified nonlinear force density method (MNFDM) is proposed. In this method, the stresses of membrane elements were transformed to the force-densities of cable nets by an equivalent relationship, and then they can be used as initial conditions. By comparing with the forming finding results by using the FDM, NFDM, INFDM and MNFDM, it had demonstrated that the MNFDM presented in this paper is the most efficient and precise.

• 한국군사과학기술학회지
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• 제19권5호
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• pp.662-668
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• 2016

Defense specification suitability review task means to examine whether to need enactment, amendment or abolition of defense specification, and realistic and efficient review environment are urgently needed by improving system. For the promotion of efficient tasks, the cycle of defense specification suitability review needs to be changed to 5 years for active specifications and 10 years for inactive specifications. To simplify the standards of defense specification suitability review, the distinction between prior management items and general management items should be abolished and the number of review items need to be reduced from ten to three. Also, in order to promote substantial defense specification suitability review, a system improvement is needed to utilize retired professionals from defense acquisition related agencies.

• 한국군사과학기술학회지
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• 제17권2호
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• pp.248-257
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• 2014

As observed in the recent war, suppression of enemy air defense operation is one of the major tactics, simultaneously conducted with high payoff target. Specifically, our air defense operation should be properly constructed, since the operating environment of our forces mostly consists with mountainous terrain, which makes detections of the enemy difficult. The effective arrangements of low altitude air defense radars can be suggested as a way of improving the detection capability of our forces. In this paper, we consider the location problem of low altitude air defense radar, and formulate it as an Integer Programming. Specifically, we surveyed the previous researches on facility location problems and applied two particularly relevant models(MCLP, MEXCLP) to our problem. The terrain factor was represented as demand points in the models. We verified the optimal radar locations for operational situations through simulation model which depicts simple battle field. In the simulation model, the performance of optimal radar locations are measured by the enemy detection rate. With a series of experiments, we may conclude that when locating low altitude air defense radars, it is important to consider the detection probability of radar. We expect that this finding may be helpful to make a more effective air defense plan.

• 한국군사과학기술학회지
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• 제11권6호
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• pp.81-89
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• 2008

University Research Centers specialized in defense technology(DURCs) were designed to develop fundamental knowledge and to acquire core technologies related to defense development by conducting creative and interdisciplinary research. The centers also have a function of fostering scientists and practitioners possessing defense-oriented cross-disciplinary knowledges. Since the outset of the DURC in 1994, Sixteen DURCs have been funded and eleven DURCs are now in operation. The purpose of this paper is to analyse the operational status and the performance of DURCs and to suggest ideas on improving the effectiveness of the DURC program by comparing with the Korea Excellent Research Center program and the U.S. National Science Foundation(NSF) Engineering Research Center(ERC) program.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권5호
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• pp.909-937
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• 2011

Energy efficiency is one of the most critical issues in the design of wireless sensor networks. In object-tracking sensor networks, the data storage and query processing should be energy-conserving by decreasing the message complexity. In this paper, a Prediction-based Energy-conserving Approximate StoragE schema (P-EASE) is proposed, which can reduce the query error of EASE by changing its approximate area and adopting predicting model without increasing the cost. In addition, focusing on reducing the unnecessary querying messages, P-EASE enables an optimal query algorithm to taking into consideration to query the proper storage node, i.e., the nearer storage node of the centric storage node and local storage node. The theoretical analysis illuminates the correctness and efficiency of the P-EASE. Simulation experiments are conducted under semi-random walk and random waypoint mobility. Compared to EASE, P-EASE performs better at the query error, message complexity, total energy consumption and hotspot energy consumption. Results have shown that P-EASE is more energy-conserving and has higher location precision than EASE.

• 한국군사과학기술학회지
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• 제26권1호
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• pp.44-53
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• 2023

Adversarial attacks have received great attentions for their capacity to distract state-of-the-art neural networks by modifying objects in physical domain. Patch-based attack especially have got much attention for its optimization effectiveness and feasible adaptation to any objects to attack neural network-based object detectors. However, despite their strong attack performance, generated patches are strongly perceptible for humans, violating the fundamental assumption of adversarial examples. In this paper, we propose a camouflaged adversarial patch optimization method using military camouflage assessment metrics for naturalistic patch attacks. We also investigate camouflaged attack loss functions, applications of various camouflaged patches on army tank images, and validate the proposed approach with extensive experiments attacking Yolov5 detection model. Our methods produce more natural and realistic looking camouflaged patches while achieving competitive performance.