• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.894-899
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• 1991

GRAFCET is the program language for a sequential control and utilized in the description of sequence of a process. This study is to implement GRAFCET editor and compiler for personnel computer. The GRAFCET editor module is developed to use as menu-driven method based on the graphic screen and the graphic symbol. So, users can use it interactively. The GRAFCET compiler module analyzes the already drawed GRAFCET diagram, then translates it to Z80 assembly code. After generating Z80 machine code from assembly code, we can send the outputed machine code file to Z80 one-board computer through RS232C. We have developed the GRAFCET programming tool to utilize under IBM PC/AT with the VGA monitor, and it may be contribute to low cost automation system.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1578-1583
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• 2003

Time-Optimal solutions for attitude control with reaction wheels as well as with thrusters are studied. The suggested varying-time-sharing ratio thrusting is found to reduce the maneuvering time enormously. The hybrid control such as sequential hybrid and simultaneous hybrid with reaction wheels and thrusters are considered. The results show that simultaneous hybrid method reduces the maneuver time very much. Spacecraft model is KOrea Multi-Purpose SATellite(KOMPSAT)-II, which is being developed by KARI in KOREA as an agile maneuvering satellite.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04b
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• pp.178-180
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• 2002

모바일 클라이언트(Mobile Client, MC) - 서버 환경에서 캐쉬된 공간 데이타는 용량과 가용성이 크고 긴단절을 가지는 특징이 있다. 이러한 긴 단절을 거친 MC의 일관성 제어시 캐쉬된 데이타 전체가 무효화되어 재전송 하는 것은 비효율적이므로 서버는 변경된 객체 정보를 로그로 기록하여, 캐쉬된 영역에 속하는 최근 변경 정보만을 전송하는 것이 필요하다. 또한 일반적으로 로그의 순차 검색과 불필요한 로그의 누적으로 인해 일관성 제어시 통신 비용이 증가하게 되므로, 서버의 로그 검색 시간과 전송량을 최소화 하기위한 기법이 필요하다. 이를 위해 본 논문에서는 로그를 이용안 공간 로그 인덱스(Spatial Log Index, SLI) 기법과 공간 로그 관리(Spatial Log Management, SLM) 기법을 제시하고 있다.

• Electronics and Telecommunications Trends
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• v.20 no.2 s.92
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• pp.1-13
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• 2005

비구조화되고 예측 불가능한 환경에서 동작하는 지능형 로봇의 제어를 위한 프로그램의 개발은 범용 컴퓨터에서 수행되는 일반 응용프로그램과는 달리 로봇이 존재하는 세계와의 복잡한 상호작용을 전제로 하고 있다. 이러한 전제는 로봇 프로그램에게 순차성과 더불어 병행성, 예외처리, 외부세계와의 인터페이스 등을 요구하며 더불어 로봇소프트웨어 제어구조가 특정 하드웨어나 플랫폼에 의존적이지 않고 여러 하드웨어 플랫폼에 두루 적용될 수 있는 구조가 요구된다. 로봇 소프트웨어 아키텍처는 이러한 요구에 기반하여 프로그래밍의 복잡성과 반복성을 줄이고 로봇을 보다 효율적으로 제어할 수 있는 구조를 제공하는 것을 목적으로 한다. 본 논문에서는 로봇 소프트웨어 아키텍처에 대한 최근의 연구동향에 대하여 살펴보고 신성장동력의 하나인 IT 기반 지능형서비스 로봇을 위한 로봇 소프트웨어 아키텍처의 최근의 연구현황에 대하여 소개한다.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.3
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• pp.213-220
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• 2008

The object of this paper is to propose a method to deal with the problem of modeling user specifications in approaches based on supervisory control and Petri nets. However, most of Petri Net approaches are based on forbidden states specifications, and these specifications are suitable the use of tool such as the reachability graph. But these methods were not able to show the user specification easily and these formalisms are generally limited by the combinatorial explosion that occurs when attempting to model complex systems. Herein, we propose a new efficient method using FSSTP (Forbidden Sequences of State-Transitions Problem) and theory of region. Also, to detect and avoid the deadlock problem in control process, we use DAPN method (Deadlock Avoidance Petri nets) for solving this problem in control model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.1
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• pp.109-116
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• 1998

In this paper, a back propagation neural network teaming algorithm based on the complex multilyer perceptron is represented for suppressing narrowband interference of the received signals in DS-SS mobile communication system. We proposed neural network adaptive correlator(NNAC) which has fast convergence rate and good performance with combining back propagation neural network and the receiver of DS-SS. We analyzed and proved that NNAC has lower bit error probability than that of traditional RAKE receiver through results of computer simulation in the presence of the tone and narrow-band interference and the co-channel interference.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.48-50
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• 2015

웹 응용 프로그램은 운영체제에서 동작하는 응용프로그램에 비해 사용의 범위와 양이 폭발적으로 증가하는 추세이다. 이러한 흐름에 맞추어 다양한 웹 응용프로그램이 개발되고 있고, 다중의 사용자가 동일한 페이지를 볼 수 있는 실시간 웹 프레젠테이션 프로그램을 폴링 기법을 활용하여 제작되고 있다. 하지만 이러한 문제가 있어 비동기 데이터의 순서제어에 관한 연구가 필요하다. 본 연구에서는 이러한 문제를 해결하기 위해 비동기 데이터의 순서 제어에 대해 연구하였고, 타임스템프 기법을 활용하여 해결하고자 하였다. 타임스템프 기법을 활용하여 클라이언트와 서버는 각각 결과의 순서와 요청의 순서를 제어하여 불필요한 통신 대역폭 낭비를 줄였으며, 순차적으로 진행 되어야 하는 프레젠테이션 응용 프로그램의 특성에 맞는 결과를 보일 수 있게 되었다.

• Aerospace Engineering and Technology
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• v.13 no.2
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• pp.18-28
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• 2014

We assume that two control moment gyros are installed for space qualification in a satellite with four reaction wheels, and study the high agile maneuver method. Using high torque control moment gyros, we reduce the satellite's attitude error. After that, we activate reaction wheels to control remaining attitude error. This proposed method can avoid singularity problem of control moment gyros, and do not require gimbals' angle to calculate torque command. Through numerical simulations, we show that our method's agile performance is similar to previous method and reduce the reaction wheels' required momentum.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.48 no.3
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• pp.40-47
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• 2011

This paper addresses the problem of fault detection and tolerance for asynchronous sequential machines using state feedback control. The considered asynchronous machine is affected by intermittent faults. When intermittent faults occur, the machine undergoes unauthorized state transitions and, for a finite duration, remains at the fault state, not responding to the change of the external input. In this paper, we postulate the scheme of detecting intermittent faults and present the existence condition and design algorithm for a robust state feedback controller that overcomes the adversarial effect of intermittent faults. We also undertake a comparative study between the previous control scheme for transient faults and the present strategy for intermittent faults. The design procedure for the proposed controller is described in a case study.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.35-43
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• 2011

Cognitive Radio (CR) ad hoc network is highly considered as one of promising future ad hoc networks, which enables opportunistic access to under-utilized licensed spectrum. Similarly to other CR networks, the spectrum sensing is a prerequisite in CR ad hoc network. Collaborative spectrum sensing can help increasing sensing performance. For such an infrastructureless network, however the coordination for the sensing collaboration is really complicated due to the lack of a central controller. In this paper, we propose a novel collaborative spectrum sensing scheme in which the final decision is made by the node with the highest data reliability based on a sequential Dempster Shafer theory. The collaboration of sensing data is also executed by the proposed contention-aware reporting mechanism which utilizes the sensing data reliability order for broadcasting spectrum sensing result. The proposed method reduces the collecting time and the overhead of the control channel due to the efficiency of the ordered sequential combination while keeping the same sensing performance in comparison with the conventional cooperative centralized spectrum sensing scheme.