• International Journal of Aeronautical and Space Sciences
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• v.8 no.2
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• pp.37-43
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• 2007

Coordination of multiple UAVs is an essential technology for various applications in robotics, automation, and artificial intelligence. In general, it includes 1) waypoints assignment and 2) trajectory generation. In this paper, we propose a new method for this problem. First, we modify the concept of the standard visibility graph to greatly improve the optimality of the generated trajectories and reduce the computational complexity. Second, we propose an efficient stochastic approach using simulated annealing that assigns waypoints to each UAV from the constructed visibility graph. Third, we describe a method to detect collision between two UAVs. FinallY, we suggest an efficient method of controlling the velocity of UAVs using A* algorithm in order to avoid inter-UAV collision. We present simulation results from various environments that verify the effectiveness of our approach.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.14-25
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• 2006

This paper is focused on designing an implementable control law to perform spacecraft various missions using momentum exchange devices such as reaction wheels(RWs) and control moment gyros(CMGs). A compact equation of motion of a spacecraft installed with various momentum exchange devices is derived in this paper. A hybrid control law is proposed for precision attitude control of agile spacecraft. The control law proposed in this paper allocates control torque to the CMGs and the RWs adequately to satisfy the precision attitude control and large angle maneuver simultaneously. The saturation problem of reaction wheels and the singularity problem of control moment gyros are considered. The problems are successfully resolved by using the proposed hybrid closed loop control law. Finally, the proposed hybrid control law is demonstrated by numerical simulations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.715-718
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• 2002

This paper investigated that resonant frequencies of microstrip patch antenna were agile when piezoelectric materials were used as the antenna substrates. When the bias is applied on them, thickness of the substrate is varied according. to the piezoelectric phenomenon. The microstrip patch antenna using Quartz substrate was fabricated and designed by Ensemble v 7.0 simulator. We fabricated the microstrip antennas using Quartz(Y-cut) as its substrate. When the operating frequencies of the microstrip antenna were 7.045GHz, 7.773GHz 8.18GHz the frequency shifts versus electric field, Emax=4[kV/cm], were 21MHz, 26MHz and 28MHz, respectively.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.947-955
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• 2004

This paper is concerned with a mixed control with aerodynamic fin and side thrust control applied to an agile missile using a dynamic inversion and a time-varying control technique. The nonlinear dynamic inversion method with the weighting function allocates the desired control inputs(aerodynamic fin and side thrust control) to achieve a reference command, and the time-varying control technique plays the role to guarantee the robustness for the uncertainties. The proposed schemes are validated by nonlinear simulations with aerodynamic data.

• The Journal of Information Technology and Database
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• v.3 no.1
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• pp.45-63
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• 1996

This paper presents an integrated object-oriented database approach for managing the evolution of products in agile manufacturing environments, Schema evolution modification facilities are provided to support full potential versioning of type definitions. All of the possible versions for a composite product are not explicitly represented to avoid version proliferation. However, valid configurations of any composite products can be provided to comply with customer demands, The attributes of composite products are classified in order to provide well-defined representation scheme for composite products and to be exploited in version control. The attributes are partitioned into composite-related and non composite-related categories. Composite-related attributes consist of subproducts and description ones. Subproducts attributes represent physical constituents of a composite product. Description attributes represent external features, assembling, and correspondence property. Interface attributes are introduced for managing configurability and version propagation. Version derivations due to the changes to the interface attributes are propagated toward the product composition hierarchy, The validity of configurations of composite products is checked by using configurability maps. Instance objects which represent the actual product instances are stored and manipulated in the database in order to support traceability during product life cycle.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.561-563
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• 2012

In this work, tunable capacitors using a finger-type electrode are designed and characterized for frequency-agile RF circuit applications. Their top electrodes with different area and line width are designed in types of the finger for a long conducting perimeter which results in enhanced fringing-electric fields in order to improve their tunability. The tunable varactors were fabricated on a quartz substrate employing a multi-layer dielectric of a para/ferro/para-electric thin film. Compared to the conventional capacitor, finger-type capacitors are characterized in terms of effective capacitance and tunablility. Their effective capacitance and tunability with the long perimeter increase 24~40% and 7~12%, respectively, due to enhanced fringing electric fields from 1 to 2.5 GHz, compared to the conventional ones.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.488-491
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• 2001

This paper investigated that resonant frequencies of micro strip patch antenna were agile when piezoelectric materials were used as the antenna substrates. The resonant frequencies of the micro strip antenna using the piezoelectric substrate. The micro strip patch antenna made of Quartz substrate was designed and fabricated by Ensemble v 7.0 simulator. The experimental problem was compensated by Ensemble v 7.0

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.607-608
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• 2006

This article deals the development of Agile and Intelligent Manufacturing System(AIM) for the assembly automation of a tiny ultrasonic actuator used in camera phones and PDAs. The system consists of multi-vision modules, end-effectors, a standard base frame, dispensers, jigs and modular manipulators. Subsystems are a vision system, a force control system and a virtual reality system. Experimental results show that the assembly process for the small components in the various IT applications can be realized by the AIM system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.620-623
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• 2002

To cope with the challenge of competitive market, manufacturing system needs to be agile in terms of its reconfigurability and scalability. For a system to be adapted to changed requirements, decision support tools such as configurator have to be provided. This paper introduces the basic framework of a configurator for assembly system Based on the factory data model(FDM) depicting the overall structure of a manufacturing system, functions of the configurator are described, i.e., requirements analysis, module selection and configuration optimization.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.106-107
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• 2018

대학의 게임개발 프로젝트에서 품질관리를 수행할 때 폭포수 개발과 같은 전통적인 개발방법론을 적용하기는 어려움이 있다. 이에 대한 대안으로 신속한 개발을 진행하는 애자일 방법론의 적용을 권고하고 그 중에서도 일정한 주기를 기반으로 실행하는 스크럼 방법론의 적용방안을 제시하였다. 본 논문에서는 스크럼 방법론을 학기의 상황에 따라 적용할 수 있도록 일부 원칙을 수정하여 제시한다. 수정된 스크럼 방법을 적용할 경우 보다 체계적인 프로젝트 진행과 품질관리가 가능할 것으로 판단된다. 스크럼의 적용 후에는 회고 과정을 거쳐 프로세스를 지속적으로 개선하는 과정도 필요하다.