• 한국통신학회논문지
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• 제18권5호
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• pp.634-642
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• 1993

본 논문에서는 로보트 매니퓰레이터 제어를 위하여 시간 지연이 있는 다층 신경회로망(TDNN)의 학습 알고리즘으로 매니퓰레이터의 역동역학 모델을 학습시키고 이것을 앞먹임(Feedforward)제어기로 사용하는 궤적 제어 방법을 새로이 제시하였다. TDNN 구조는 뉴런이 현재 및 과거의 입력 신호로부터 더 많은 정보를 추출할 수 있고 보다 효율적으로 학습할 수 있는 유리한 특징을 가지고 있다. TDNN 신경회로망은 기준 궤적 입력 신호와 비례 미분 제어기의 오차 신호를 각각 정규화하여 받아드린다. TDNN 신경회로망으로 입력되는 정규화 신호는 TDNN 신경회로망의 학습 효율을 향상시키는 것으로 입증되었다. 제안된 제어 방법을 두개의 관절을 가진 평면 로보트 매니퓰레이터에 대하여 적용하고 컴퓨터 시뮬레이션으로 고찰하였다.

• 한국해양공학회지
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• 제23권5호
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• pp.61-70
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• 2009

An AUV (Autonomous Underwater Vehicle) is an unmanned underwater vessel to investigate sea environments and deep sea resource. To be completely autonomous, AUV must have the ability to home and dock to the launcher. In this paper, we consider a class of homing trajectory planning problem for an AUV with kinematic and tactical constraints in horizontal plane. Since the AUV under consideration has underactuated characteristics, trajectory for this kind of AUV must be designed considering the underactuated characteristics. Otherwise, the AUV cannot follow the trajectory. Proposed homing trajectory panning method that called VGM (Virtual Goal Method) based on visibility graph takes the underactated characteristics into consideration. And it guarantees shortest collision free trajectory. For tracking control, we propose a PD controller by simple guidance law. Finally, we validate the trajectory planning algorithm and tracking controller by numerical simulation and ocean engineering basin experiment in KORDI.

• 산업기술연구
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• 제20권B호
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• pp.155-162
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• 2000

Although Fuzzy Logic Controller(FLC) adopted three terms as input gives better performance, FLC is in general composed of two-term control because of the difficulty in the construction of fuzzy rule base. In this paper, a three-term FLC which is similar to PID control but acts as a nonlinear controller is proposed. To reduce the complexity of the rule base design and to increase efficiency. a simplified fuzzy PID control is induced from a hybrid velocity/position type PID algorithm by sharing a common rule base for both fuzzy PI and fuzzy PD parts. It is simple in structure, easy in implementation, and fast in calculation. The phase plane technique is applied to obtain the rule base for fuzzy two-term control and the resultant rule base is Macvicar-Whelan type. And the membership function is a Gaussian function. The frequency response information is used in tuning of the membership functions. Also a tuning strategy for the scaling factors is proposed based on the relationship between PID gain and the scaling factors. Simulation results show better performance and the effectiveness of the proposed method.

• 조명전기설비학회논문지
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• 제25권8호
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• pp.30-38
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• 2011

This paper proposes a new intelligent diagnosis equipment for the partial discharge, which keeps deteriorating the insulating materials inside electric machineries, ultimately leading to electrical breakdown. In order to simulate experimentally the partial discharge inside the electric machinery, the tip-to-plate, the sphere-to-plate, the sphere-to-sphere and the plate-to-plate electrodes are used respectively, of which the gaps are 1[mm], 3[mm] or 5[mm] and the applied voltages are 3[kV], 5[kV] or 7[kV]. Ceramic coupler sensor and FIR digital filter are used to measure the partial discharge and the artificial neural network is used for the deterioration diagnosis of the electric machinery. The microprocessor of PD diagnosis equipment is DSP (TMS320C6713) with FPGA (Cyclone II). The results of the real-time and on-line experiments performed with the developed equipment are also explained.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1726-1728
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• 2003

The aging diagnosis method using partial discharge measurement detects discharge signals that critical cause of failure in insulation material operated a long time and can diagnose aging state of insulation materials with an aging analysis algorithm. The HFPD measurement method is a technique to analyze aging state of high voltage insulation materials and detect higher frequency signals than conventional PD measurement method therefore it takes less noise effect and could execute active line measurement. It is possible to analyze main discharge phenomena and obtain access to aging progress occurred in insulation materials through accumulation of HFPD signals during determined interval and expression of fractal dimension using statistical process of accumulated signals. The HFPD signals that occurred in each applied voltages are measured during 180 cycles and accumulated to the same phase of one cycle. These patterns that made by previous method are normalized with logarithm function and than inputted to neural networks. The aging diagnosis of insulation material was possible and the recognition ratio of neural network appeared very high.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권3호
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• pp.185-191
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• 2008

In this paper, experimental studies of a neural network (NN) control technique for non-model based position control of the x-y table robot are presented. Decentralized neural networks are used to control each axis of the x-y table robot separately. For an each neural network compensator, an inverse control technique is used. The neural network control technique called the reference compensation technique (RCT) is conceptually different from the existing neural controllers in that the NN controller compensates for uncertainties in the dynamical system by modifying desired trajectories. The back-propagation learning algorithm is developed in a real time DSP board for on-line learning. Practical real time position control experiments are conducted on the x-y table robot. Experimental results of using neural networks show more excellent position tracking than that of when PD controllers are used only.

• 대한건축학회논문집:계획계
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• 제36권4호
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• pp.103-111
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• 2020

Perforated metal sheets are used as panels of facades for controlling environmental factors while ensuring user's visibility. Despite their functional potentials, only a specific direction of facades or an orientation of a building was considered in the relevant studies. This study proposed a design methodology for the perforated panel facades that reflects the location on the facades and the user's requirements. The optimization of quantitative and qualitative performance is achieved through communication between designers and users in a VR system. In optimizing quantitative performances, designers use machine learning techniques such as clustering and genetic algorithm to allocate optimal panels on the facades. In optimizing qualitative performances, through the VR system, users intervene in evaluating performances whose preferences are depending on them. The experiment using the office project showed that designers were able to make decisions based on clustering using GMM to optimize multiple quantitative performances. The gap between the target and final performance could be narrowed by limiting the types of perforated panels considering mass customization. In assessing visibility as a qualitative performance, users were able to participate in the design process using the VR system.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.314-324
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• 2020

Due to the nonlinearity and environmental uncertainties, the design of the ship's steering controller is a long-term challenge. The purpose of this study is to design an intelligent autopilot based on Extended Kalman Filter (EKF) trained Radial Basis Function Neural Network (RBFNN) control algorithm. The newly developed free running model scaled surface vessel was employed to execute the motion control experiments. After describing the design of the EKF trained RBFNN autopilot, the performances of the proposed control system were investigated by conducting experiments using the physical model on lake and simulations using the corresponding mathematical model. The results demonstrate that the developed control system is feasible to be used for the ship's motion control in the presences of environmental disturbances. Moreover, in comparison with the Back-Propagation (BP) neural networks and Proportional-Derivative (PD) based control methods, the EKF RBFNN based control method shows better performance regarding course keeping and trajectory tracking.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.96-103
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• 2023

This paper presents a robust position tracking controller for a motor used in semiconductor equipment, utilizing the motor angle measurement. Precise position control is challenging due to the presence of uncertainties in various motor applications. The proposed controller consists of a PD (Proportional-Derivative) controller and a PIO (Proportional-Integral Observer) to estimate the system's state and equivalent disturbance compensating for the uncertainties. Since the stability alternates as the observer gain increases, we have investigated it through the closedloop root locus under the system parameters change. The analysis has showed that the inertia of the motor is the main parameter that affects it, and by adjusting the control gain appropriately, the system can be rendered to be stable even when the inertia of the motor changes. The effectiveness of the proposed control algorithm is validated through computer simulations, followed by a comparison of its performance with the results of a previous study.

• 대한핵의학회지
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• 제39권1호
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• pp.9-14
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• 2005

목적 : 좌각차단이나 우심실조율박동과 같은 부정맥을 가진 환자들에서 심근관류는 의미있게 변화한다는 것이 알려져 있다. 비정상적인 심근관류는 심실조기흥분에 의해서도 야기될 수 있다고 알려져 있지만, 그 위치 범위 강도와 부전도로와의 관계는 아직 정립되어 있지 않았다. 이에 WPW 증후군 환자에서 부전도로의 위치와 SPECT상에서 관류양상의 관계에 대해 알아보고자 하였다. 대상 및 방법 : WPW 증후군 환자 11명에 대해 Adenosine 99m-Tc MIBI 또는 Tl-201 심근관류 SPECT를 시행하였다, 관류결손은 Fitzpatrick's algorithm을 기초로 한 심전도 또는 전기생리학적검사 및 전극도자 절제술을 이용한 부전도로의 위치와 비교하였다. 결과: 11명의 환자들의 평균 나이는 $39.9{\pm}8.6$세 였고, 비특이적인 흉통을 호소하거나, 증상이 없었다. 11명 모두 관삳동맥의 위험도에 관한 계산도표를 이용하여 관상동맥질환의 확률을 예측했으나 0.1 이하로 위험도가 낮았고 이중 4명은 관상동맥조영술을 시행한 결과 3명은 정상이었고 1명은 관동맥 협착 (50%) 부위의 심근혈류가 정상이었다. 4명의 환자에서 전기생리학적검사 및 전극도자 절제술을 시행하였다. 9명의 가역적 그리고 1명의 비가역적 관류결손이 관찰되었고. 범위는 소에서 대까지 강도는 경도에서 중등도까지 나왔다. 부전도로의 위치가 우외측인 1명은 관류결손이 없었으나, 그 외의 환자들은 다양한 양상을 보였다. 부전도로의 위치가 좌외측인 환자중 1명에 대해 전극도자 절제술을 시행하였고 6주후에 SPECT를 한 결과 시술 전에 있던 관류결손의 범위가 현저하게 감소하였다. 결론: WPW환자에서 심근관류결손은 다양한 범위, 강도 및 위치를 가진다. 거의 대부분의 환자에서 비정상적인 관류결손이 나타났으나, SPECT 소견으로 부전도로의 위치를 특이적으로 예측하기는 어려웠다. 그러므로 WPW증후군 환자에서 심근관류 SPECT의 결과를 주의 깊게 해석해야 한다.