• Journal of the Korean Society for Precision Engineering
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• v.14 no.7
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• pp.154-162
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• 1997

본 논문은 구속된 기계 시스템의 운동 제어 설계를 위한 새로운 방법을 제안한다. 구속된 기계 시스템의 운동 제어에는 지금까지 주로 사용되어온 Lagrange의 운동 방정식에 의한 모델링 보다 Udwadia와 Kalaba에 의해 제안된 운동 방정식에 의한 모델링이 더욱 적합함을 보였으며 이는 Holonomic 및 Nonholonomic 구속 조건을 비롯한 대부분의 구속 조건이 포함된다. 문헌에 잘 알려진 두 시스템을 시뮬레이션을 통하여 비교 함으로써 본 논문에 제안된 방법이 보다 우수한 결과를 보여줌을 확인 할 수 있었다. 또한 지금까지 불가능 하였던 비선형 일반 속도(gereralized velocity)를 포함한 구속 조건도 용이하게 제어됨을 보임으로써 광범위한 구속된 기계 시스템의 제어 문제를 통일된 방법으로 접근 할 수 있음을 제시하였다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.115-120
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• 2003

일반적으로 광학위성은 궤도가 부정확하여 지상기준점(GCP)을 이용하여 궤도를 보정하는 작업을 수행한 후 수치 표고모형 자료(DEM)를 추출한다. 지상기준점은 실제 측량이나 지형도로부터 얻게 되지만, 이러한 작업이 불가능한 경우에는 광학영상으로부터 수치 표고 모형 자료를 추출할 수 없다. 본 연구에서는 수-수십 cm의 위성 궤도 정확도를 지니는 ESA ERS영상과 약 1Km의 해상도를 지니는 GTOPO-30 DEM을 이용하여 지상기준점을 추출 방법에 대해 연구하였다. 연구지역인 대전 주변에 대하여 지상기준점을 추출한 결과 경도 -0.348초, 위도 0.293초의 오차를 나타내었다. 또한 추출된 지상기준점을 이용하여 한 쌍의 SPOT 위성영상으로부터 DEM을 추출이 가능하였으며, 레이더 interferometry 기술을 이용한 지형고도 추출 및 변화 탐지에도 활용될 수 있음을 확인하였다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2003.04a
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• pp.135-138
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• 2003

레이더 interferometry 기법을 이용하여 1995년 12월 11일과 12일에 획득된 ERS-1(orbit: 23180, frame 2853), ERS-2(orbit: 03507, frame: 2853) tandem 자료로부터 서해안(강화도-아산만) 지역의 조간대 DEM을 추출하였다. 사용된 SAR 자료는 영상획득 당시의 낮은 조위(ERS-1: 0.89 cm, ERS-2: -0.02 cm), 짧은 시간 간격(1일), 그리고 비교적 긴 기선 간격(270 m 수직 baseline)을 갖기 때문에 조간대 DEM 추출에 매우 적합하였다. 비록 추출된 DEM의 정확도 평가는 수행되지 않았지만 기존에 광학영상으로부터 추출된 남양만 지역의 waterline과 시각적으로 단순 비교될 수 있었다. 보다 정밀한 정확도 평가는 본 연구에서 사용한 자료와 같은 날 획득된 곰소만 지역의 자료(frame: 2886)를 사용하여 waterline 방법으로 추출된 DEM 및 현장 측량자료를 이용하여 수행될 것이다. Temporal 그리고 baseline decorrelation 등을 무시하고 SAR 영상의 위상측정 오차만을 이용하여 계산된 고도 정밀도는 SNR 20 dB에서 약 0.57 m이다.

• Journal of the Korean Society of Physical Medicine
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• v.4 no.1
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• pp.15-21
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• 2009

Purpose : The purpose of this study was to find the effect of ankle joint angle on knee extensor electromyographic activity following knee extension exercise. Methods : Ten male university students participated in the study. The subjects performed isometric maximal voluntary knee extensor contractions (MVC) and knee extensor EMG activity measured in with three different ankle joint angle. The EMG activity of rectus femoris(RF), vastus medialis(VM), vastus lateralis(VL) were measured using surface electromyography. Results : EMG activity of vastus lateralis following the change of ankle joint angle was shown statistically significant difference. Conclusion : Ankle plantar flexion position increase EMG activity of vastus lateralis during knee extension exercise.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.279-281
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• 2006

In this paper, we study an approach to design a self-tuning Fuzzy-PI controller in HVDC(High Voltage Direct Current) system. In the rectifier of conversional HVDC system, turning on, turning off, triggering and protections of thyristors have lots of problems that can make the dynamic instability and cannot damp the dynamic disturbance efficiently. The above problems are solved by adapting Fuzzy-PI controller for the fire angle control of rectifier.[7] The performance of the Fuzzy-PI controller is sensitive to the variety of scaling factors. The design procedure dwells on the use of evolutionary computing(Genetic Algorithms, GAs). Then we can obtain the optimal scaling factors of the Fuzzy-PI controller by Genetic Algorithms. In order to improve Fuzzy-PI controller, we adopt FIS to tune the scaling factors of the Fuzzy-PI controller on line. A comparative study has been performed between Fuzzy-PI and self-tuning Fuzzy-PI controller, to prove the superiority of the proposed scheme.

• Journal of Drive and Control
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• v.13 no.3
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• pp.53-66
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• 2016

New non-hybrid approaches to improve energy efficiency of construction machineries are reviewed in this paper. Hydraulic systems are classified into four classes according to Backe's classification and commercially promising new technologies are carefully chosen in each class. IMV, 3-Line CPR, Closed Circuit Displacement Control of Differential Cylinder, and Throttle-less Secondary Control are chosen as representative non-hybrid new technologies. Key principle of each technology is explained and representative references which run through each technology are selected. Advantages and weaknesses of each technology are discussed and compared from the view point of construction machinery manufacturers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1236-1240
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• 2014

We propose a robot museum, "ROSIEUM," based on a new concept of museum. Roles of a new concept based museum are being investigated. We also propose a classification scheme for robot contents as museum's collections. This scheme for collecting and displaying robot contents includes the first robots, the delegate robots, the robots with special meanings, the robot experiences and the robot events. Also, types of robot contents are described. Key ideas and scenario for "ROSIEUM" have been presented. Operations of "ROSIEUM" are designed and implemented.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.386-386
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• 2000

Cell mapping is a powerful computational technique for analyzing the global behavior of nonlinear dynamic systems. It simplifies the task of analyzing a continuous phase space by partitioning it into a finite number of disjoint cells and approximating system trajectories as cell transitions. A cell map for the system is then constructed based on the allowable control actions. Next search algorithms are employed to identify the optimal or near-optimal sequence(s) of control actions required to drive the system from each cell to the target cell by an "unravelling algorithm." Errors resulting from the cell center-point approximation could be reduced and eliminated by fuzzifying the bonders of cells. The dynamic system control method based on the cell mapping has been demonstrated for a motor control problem.l problem.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.532-532
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• 2000

Conventional artificial intelligence systems are not properly responding under dynamically changing environments. To overcome this problem, reactive planning systems implementing new Al principles, called behavior-based Al or emergent computation, have been proposed and confirmed their usefulness. As another alternative, biological information processing systems may provide many feasible ideas to these problems. Immune system, among these systems, plays important roles to maintain its own system against dynamically changing environments. Therefore, immune system would provide a new paradigm suitable for dynamic problem dealing with unknown environments. In this paper, a new approach to behavior-based Al by paying attention to biological immune system is investigated. The feasibility of this method is confirmed by applying to behavior control of an autonomous mobile robot in cluttered environment.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.33-40
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• 2010

Vibration of a hydraulic excavator's body and boom occurs when the boom quickly stops after upward or downward motion. The main objective of this research is to present an idea of suppressing the vibration. Three parameters which affect the vibration are defined and analyzed thoroughly and a heuristic method suppressing the vibration is presented in this paper. Experimental results show that the proposed method works very well.