• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.922-931
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• 2017

This research paper describes design procedures and those verification with multi-body dynamic analysis and an experiment for the development of an unprecedented type of canister cover, named as the separating cover. In order to overcome drawbacks from the precious rupture type and actuator driven cover, the separating cover was suggested. It has the simplest structure composed of the previously developed explosive bolt and a spring-lever driven system. First of all, mechanical feasibility with proposed design parameters based on mathematical modeling was confirmed through dynamic analysis and then its results showed good agreement with the followed empirical results acquired from a high speed camera. On top of that, a parametric study was conducted to identify the effect of each design parameter on separating performance. It is highly expected that this research contributes to provide military industries with a brand new canister cover having simplicity and cost efficiency and thus it will be very useful in MLRS(Multiple Launch Rocket System).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1210-1220
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• 2016

As modern warfare has changed into network centered, the ability to share situational awareness among allies become a core competency for performing operational missions. In an airborne environment, it uses a tactical data link such as Link-16 for shared situational awareness. There exist problems when it shares situational awareness over the existing data link that can not allocate slots dynamically or that can not change the number of a slot to be allocated. In addition, there was a problem that can not share this failure so that failed to improves situation awareness because of finite time slot resources. In this paper, we accommodate dynamic slot allocation and changes of slot allocation with mixed structure of TDMA (time division multiple access) and random access. We propose a technique that can be used when available slots are exhausted, and a load balancing method to prevent slot allocation delay when slot requesting or message sending is concentrated on a single subframe.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.1
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• pp.9-22
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• 2022

A fighter performing a reconnaissance mission is equipped with a pod that drives optical/infrared sensors for acquiring and identifying target information on the lower part of the fuselage. Due to the nature of the reconnaissance mission, the fighter performs high speed evasive maneuvers, and the resulting load should be considered importantly for the development of the pod. This paper concerns a numerical investigation into the inertial and aerodynamic loads of the airborne pod of high performance aircrafts. For the aerodynamic load analysis, the pylon and pod shapes are added to the fighter 3D model, and the commercial software was used for static and dynamic analysis. Considering the practical mission conditions, the common/extreme conditions were established respectively in the static and dynamic situations of pods and the driving torque could be tripled under dynamic conditions. In the analysis of inertia load, a 3-DOF model considering roll and turning maneuvers was derived by the Lagrangian method, and then the numerical integration method was applied to the analysis. As a results, it was conformed that the inertia load was generally induced at a low level compared to the aerodynamic load, but depending on the unbalance mass condition of the pod, the inertia load cannot be negligible.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.3
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• pp.244-252
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• 2015

This paper describes design and construction results of the measurement system developed on the purpose of measuring properties of AC magnetic field sensors used in the weapon system. The system for measuring the properties of AC magnetic field sensors consist of 3-axis helmholtz coil, signal generator, signal amplifier, sensor data acquisition unit and AC magnetic field sensor property measurement & analysis equipment including the operating software. By using this system, we can measure various properties of AC magnetic field sensor such as sensitivity, linearity and dynamic response in the frequency from 1 Hz to 10 kHz. Finally we also verified its performance by measuring the property of a MAG 639, standard magnetic field sensor of bartington instruments, with the developed measurement system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.5
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• pp.380-385
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• 2020

Over the past decade, small robots have been of particular interest in the engineering field. Among the various types of small robots, biomimetic robots, which mimic animals and insects, have been developed for special activities in areas where humans cannot physically access. The optimal motion of a walking robot can be determined by the characteristics of the traversed surface (e.g., roughness, curvature, slope, materials, etc.). This study proposes three types of piezoelectric structures using different driving mechanisms, depending on the application range of the small walking robots. Dynamic modeling using computer-aided engineering optimized the shape of the robot to maximize its moving characteristics, and the results were also verified through its fabrication and experimentation. Three types of robots, named by their actuator shapes as I, π, & T-shape, were proposed regarding application for small scale ambulatory robots to different terrain conditions. Among these, the T-shaped robots were shown to have a wide range of speeds (from 2 mm/s up to 255 mm/s) and good carrying capacity (up to 10 g at 50 mm/s) through driving experiments. Based on this study, we proposed possible application areas for the three types of walking robot actuators.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.195-203
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• 2017

This paper is concerned with the active vibration control of shell structure that is subjected to internal unbalanced excitation by using active mounts and accelerometers. The unbalanced excitation is caused by a rotating unbalanced mass. The control algorithm considered in this study is the negative acceleration feedback (NAF) control. A simplified dynamic model was derived to verify the effectiveness of the NAF control. Four actuators and four accelerometers were mounted on the shell structure, so that the multiple-input and multiple-output (MIMO) NAF controller was designed by both centralized and decentralized ways. Numerical results show that both the decentralized and centralized NAF controllers are effective. Based on the numerical simulation, the proposed decentralized NAF controller was applied to the real shell structure. Experimental results show that the proposed decentralized NAF controller can effectively suppress vibrations of the shell structure.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.469-470
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• 2014

동적 무기할당 문제는 전형적인 NP-완전 문제로써 위협하는 표적에 대해 아군의 무기를 적절히 할당하는 문제이다. 이는 매우 시간 제약적인 문제로써 가능한 단 시간 내에 적절한 무기할당 및 대응을 도출하여야 하지만 매우 유동적인 전장 환경에서 이는 쉽지 않다. 최근 이와 같이 높은 복잡성을 가진 빅데이터를 기반으로 하는 응용에서 분산 처리 시스템을 활용한 분석 및 처리에 대한 연구가 큰 주목을 받고 있고, 대표적인 프레임워크로써 맵리듀스가 활용되고 있다. 그러나 맵리듀스는 전체 데이터에 대한 일괄 처리 기능만을 제공하므로 동적 데이터에 대한 유전자 알고리즘의 수행이 쉽지 않고, 최종 결과 도출에 여전히 많은 시간을 필요로 한다. 본 논문에서는 맵리듀스 환경에서 유전자 알고리즘 기반의 동적 무기할당 알고리즘을 제안한다. 제안하는 기법에서는 맵리듀스 환경에서 유전자 알고리즘의 연속적인 데이터 처리의 지원을 위해 새롭게 추가 및 제거된 무기-표적 데이터만을 분석하고, 이를 기 분석 완료된 데이터와 결합하여 최종 결과를 도출한다. 이를 통해, 신속한 동적무기할당의 수행이 가능하다.

• Journal of Powder Materials
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• v.6 no.1
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• pp.69-74
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• 1999

The microstructure of the reagion of carters, created by Cu and W-Cu shaped charge jets, in a 1020 mild steel target has been intestiaged. The region ahead of the crater created by the Cu shaped charge jet, reveals dramatic grain refinement implying the occurrence of a dynamic recrystallization, while that of W-Cu one dose a martensitic transformation indicative of heating up to an austenitic region followed by rapid cooling.The impacting pressure calculated when the W-Cu shaped charge jet encounters the target is higher than that of the Cu one. The micro-hardness of the region ahead of the crater created by the W-Cu shaped charge jet is also higher than that of the Cu one. The microstructure of W-Cu slug remained in the inside of the craters depicts the occurrence of the remarkable elongation of W particles during the liner collaphse. From these results, the microstructural variation of the region ahead of the crater with Cu and W-Cu shaped charge jets is discussed in trems of the pressure dependency of the transformation region of ferrite and austenite phases.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.12
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• pp.1015-1023
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• 2001

error behaviour can be considered as a linear combination of low amplitude random noise and abrupt jumps. The reason of jump appearance can be explained by the semi-shading effects(buildings, trees), jamming, high dynamic of vehicle and so on. This study describes the stand-alone GPS error jump smoothing algorithm which is developed based on the scalar adaptive filter. The algorithm consists of the coarse jump smoothing and the fine jump smoothing. On the coarse smoothing step, GPS velocities or position differences are used as the measurement for the scalar adaptive filter. The purpose of adaptive filter is to smooth the jump errors. The coarse positions are detennined by the integration of smoothed velocities. On the fine smoothing step, the differences between GPS positions and the coarse positions are smoothed by another scalar adaptive filter. The reason of fine smoothing is based on the facts that smoothing accuracy depends on the variance ofusefuJ signa\. The coarse smoothing which deal with the difference of positions provides the rough error removing. So the coarse smoothed velocities can have much more low amplitude than the raw ones. The fine smoothing procedure provides high quality of filtering process. Simulation results show the efficiency of proposed scheme.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.409-414
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• 2015

M125 booster is one of the reliable S&A device(safety and arming device) to determine the arming distance of fuze for gun ammunitions from 90 mm to 8 inch in diameter. And it is also well known that the arming distance of M125 booster is determined by the multiplication value of the gun tube property(traveled distance per turn of projectile) and the S&A device property(number of turns to arm), not by the projectile muzzle velocity. We have tried and succeeded in executing a proper analysis on M125 booster to figure out its characteristic constant of arming distance by considering only the gun tube properties and the S&A device properties. More detailed arming distance will be analyzed in the future by considering dynamic characteristics on all elements in the S&A device with vector analysis.