• Journal of Magnetics
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• 제16권2호
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• pp.114-119
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• 2011

This paper presents a magnetization modeling method combined with material sensitivity information to identify the unknown magnetization distribution of a hull and improve the accuracy of the predicted fields. First, based on the magnetization modeling, the hull surface was divided into three-dimensional sheet elements, where the individual remanent magnetization was assumed to be constant. For a fast search of the optimum magnetization distribution on the hull, a material sensitivity formula containing the first-order gradient information of an objective function was combined with the magnetization modeling method. The feature of the proposed method is that it can provide a stable and accurate field solution, even in the vicinity of the hull. Finally, the validity of the method was tested using a scale model ship.

• 대한산업공학회지
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• 제39권6호
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• pp.461-472
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• 2013

In this paper, we deal with a simulation-based reliability and maintainability design problem of a warship and want to determine the optimal values of MTBF and MTTR of all units and ALDT of the warship. The system availability and life cycle cost are used as optimization criteria and estimated by simulation. A hybrid genetic algorithm with a heuristic method is proposed to find near-optimal solutions and numerical examples are also studied to investigate the effect of model parameters to the optimal solutions and compare with a general genetic algorithm.

• 한국군사과학기술학회지
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• 제13권4호
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• pp.612-618
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• 2010

In order to successfully manage of the state-of-the-art weapon system R&D program which are under the limited budget and schedule but also has a high level of technical risks, it is gaining weights to use such a scientific program management tool as TPM. Therefore, the purpose of this research is to review the concept of the TPM and its relation among MOE, MOP and TPM, and introduce an application method of TPM mainly focusing on helicopter development program. It has the organized structure, detailed procedure and 282 parameters for performance management through the TPM.

• 한국군사과학기술학회지
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• 제22권5호
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• pp.590-598
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• 2019

Aerial photographs taken by an image sensor fixed on a flight body, e.g. without a gimbal, are generally distorted according to its attitude, altitude and angle of view in flight. This can result in a significant difficulty of analyzing geometric information which should be integrated for numerous still frames. In this study, a simulation method of observation performance that uses geometric relationships between navigation data and image data is suggested, and this method is shown to be very useful for easily examining the integrated information such as the total range of photography, the time of target acquisition, etc.

• 한국군사과학기술학회지
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• 제22권2호
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• pp.215-223
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• 2019

A high temperature adhesive development which is crosslinked in low temperature is necessary for aerospace application because of thermal expansion mismatches of various substrates. For this purpose, we have designed and fabricated several formulations with high temperature epoxy resins, crosslinkers and additives considering various working conditions and high service temperature. As a result, some formulations showed higher adhesive strengths than Hysol EA 9394/C2 which is widely used for aerospace applications. We also have studied and summarized the mechanical properties of the best development adhesive in both room and high temperatures.

• 전기학회논문지
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• 제68권4호
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• pp.566-572
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• 2019

This paper proposes a new composite guidance law that can intercept moving targets and satisfy look angle rate constraint. In order to obtain the composite guidance law, we first develop a new look angle rate control guidance law which can maintain the maximum look angle rate limitation. And then, we propose the composite guidance scheme on the basis of the look angle rate control guidance and the proportional navigation guidance. To investigate the capturablity and characteristics of the proposed guidance, we also derive closed-form solutions and perform various numerical simulations. The proposed composite guidance only requires the line-of-sight rate, closing velocity, and missile's speed, thereby easily implementing in practical homing missiles.

• 한국군사과학기술학회지
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• 제26권4호
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• pp.361-370
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• 2023

Swarm has recently become a critical component of offensive and defensive systems. Multi-agent reinforcement learning(MARL) empowers swarm systems to handle a wide range of scenarios. However, the main challenge lies in MARL's scalability issue - as the number of agents increases, the performance of the learning decreases. In this study, transfer learning is applied to advanced MARL algorithm to resolve the scalability issue. Validation results show that the training efficiency has significantly improved, reducing computational time by 31 %.

• 한국군사과학기술학회지
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• 제27권1호
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• pp.31-42
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• 2024

In this study, the methodology of determination of base bleed motor data for base bleed projectile based on the NATO standard trajectory model, especially STANAG 4355 Method 2 were presented. Ground combustion experiments and aerodynamic performance firing tests were conducted to determine the drag reduction motor data of the base bleed projectile and this data was described based on the NATO standard ballistic model. The derived drag reduction motor data were input into the ballistic equations to complete the ballistic model and it was confirmed that the calculated predicted trajectory from the ballistic model matched well with the measured trajectory from the aerodynamic performance firing tests.

• 한국항행학회논문지
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• 제22권4호
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• pp.311-318
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• 2018

본 논문에서는 소형발사체의 무선통신 시스템 검증을 위한 테스트 베드를 제안한다. 제안하는 테스트 베드는 안테나 테스트 커플러와 RF 감쇄기 및 스위칭 시스템으로 구성되어 있다. 안테나 테스트 커플러는 소형 발사체에 장착되어 있는 각 대역별 안테나를 서로 격리 시키며 무선신호를 송/수신하기 위한 장치이며 RF 감쇄기 및 스위칭 시스템은 각 대역의 안테나별 통신점검을 위하여 안테나별 경로를 선택해 주는 장치이다. 안테나 테스트 커플러 설계 결과, UHF-, S-, X-대역에서 39.3, 47.1, 56.1 dB 이상의 차폐율을 확인 할 수 있었다. 실제 소형 발사체에 적용하여 발사체 통신 시스템을 점검한 결과, 정상적으로 데이터 송/수신을 확인 할 수 있었으며, 안테나 경로 스위칭을 통하여 각 대역의 안테나별 통신 점검을 수행할 수 있었다.

• 산업경영시스템학회지
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• 제46권4호
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• pp.229-237
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• 2023

In this research, a new Test and Evaluation (T&E) procedure for defense AI systems is proposed to fill the existing gap in established methodologies. This proposed concept incorporates a data-based performance evaluation, allowing for independent assessment of AI model efficacy. It then follows with an on-site T&E using the actual AI system. The performance evaluation approach adopts the project promotion framework from the defense acquisition system, outlining 10 steps for R&D projects and 9 steps for procurement projects. This procedure was crafted after examining AI system testing standards and guidelines from both domestic and international civilian sectors. The validity of each step in the procedure was confirmed using real-world data. This study's findings aim to offer insightful guidance in defense T&E, particularly in developing robust T&E procedures for defense AI systems.