• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.399-402
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• 2000

본 논문에서는 Windows 환경에서 동작하는 문서 편집기상에서 사용자의 명령을 음성으로 입력받아 글자 크기 및 화면의 이동속도를 조절하는 시스템을 연구하였다. 입력된 명령으로부터 추론된 글자 크기 값을 중심으로 font size 변경 범위를 1/2씩 줄여감으로써 사용자가 만족하는 글자 크기로 접근해 가는 방법을 사용하였다. 화면의 이동 속도는 사용자가 선택한 명령 부근에서는 원하는 이동 속도로 근접할 것이라는 개념을 도입하여 사용자가 원하는 속도로 접근하는 방법을 사용하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.842-850
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• 2014

This paper presents a trajectory tracking controller for rotorcraft UAVs to improve the tracking performances in the presence of various uncertainties. The proposed tracking method consists of a velocity guidance law based on the relative distance and L1 adaptive augmentation loop for tracking the velocity commands. In the proposed structure, the desired velocity generated by the guidance law is the reference value of the adaptive controller for accurate path tracking. In the guidance law, the desired acceleration is generated based on the relative distance and its derivatives, and then the velocity command of the inner control loop is calculated by integrating the accelerations. $L_1$ augmentation loop supplements the linear controller to guarantee the flight performances such as a tracking accuracy in the presence of the uncertainties. The proposed controller was validated in actual flight tests to successfully demonstrate its capability using a quadrotor UAV.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.5
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• pp.308-316
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• 2003

This paper describes a tracking control for the mobile robot based on fuzzy systems. The conventional back-stepping controller includes the dynamics and kinematics of the mobile robot, which is affected by the derived velocity reference by a kinematic controller. To improve the performance of conventional back-stepping controller, this paper uses the fuzzy systems known as the nonlinear controller. In this paper, the new velocity reference for the back-stepping controller is derived through the fuzzy inference. Fuzzy rules are selected for gains of the kinematic controller. The produced velocity reference has properly considered the varying reference trajectories. And simulation results show that the proposed controller is more robust than the conventional back-stepping controller.

• Journal of Korea Multimedia Society
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• v.12 no.4
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• pp.512-520
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• 2009

Maximum intensity projection (MIP) is a volume rendering method which extracts maximum values along the viewing direction through volume data. It visualizes high-density structures, such as angio-graphic datasets so that it is frequently used in medical imaging systems. We have proposed an efficient two-step MIP acceleration method that uses the recent CPUs. First, we exploited SIMD instructions to reduce conditional branch instructions which take up a considerable part of whole rendering process, so that we improved rendering speed. Second, we proposed a new method, which accesses volume and image data successively by modifying the shear-warp rendering. This method improves memory access patterns so that cache misses are reduced. Using the current CPUs, our method improved the rendering speed by a factor of 7 than that of the shear-warp rendering.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.2
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• pp.114-120
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• 2011

This paper presents a cooperative standoff tracking of a moving target using multiple unmanned aircraft. To provide guidance commands, vector fields are designed utilizing the Lyapunov stability theory. A roll angle command is generated to keep a constant distance from the target in a circular motion. A speed command and a heading angle command are designed to keep a constant phase angle with respect to the front aircraft and to prevent a collision between aircraft. Numerical simulation is performed to verify the tracking and collision performance of the proposed control laws.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.157-160
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• 2001

본 논문에서는 강수량과 자동차 주행속도 등의 환경조건에 따라 와이퍼 속도를 일정하게 적용한 기존의 시스템을 개선하여 운전자의 개인 특성에 의해서도 속도 변경이 가능하게 함으로서 인간에게 조금 더 친밀감을 제공하는 시스템을 구현하였다. 초기 와이퍼 속도는 입력받은 강수량과 자동차 주행 속도로 추론하여 구하였다. 추론된 와이퍼 속도를 운전자의 개인 특성에 따라 변경하고자 할 경우, 해당 음성명령을 입력받아 재 추론하였다. 음성인식을 위해서는 고립단어 인식에 적절한 DTW방식을 사용하였고, 와이퍼 속도는 퍼지 추론을 적용하여 구하였다.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.617-624
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• 2003

This paper proposes a modified DCPC (Distributed Constrained Power Control, M-DCPC) algorithm that can improve the performance of a CDMA power control system. The control performance of the proposed method is verified using two performance measures : the SIR response of each mobile and the outage probability in a cell. As regards the SIR response, in simulations, the M-DCPC algorithm has shown a faster convergence and lower overshoot in transient time than the other power control algorithms when the desired SIR value was varying. For the outage probability. M-DCPC converged to a fixed outage rate faster than CSOPC while also maintaining the system capacity to make as high a connection as CSOPC. In particular, when the desired SIR was varying, CSOPC showed an abrupt outage probability increase during the desired SIR Increase, yet M-DCPC was unaffected.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.871-885
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• 2015

The improved DFSA for 2.4GHz multi-tags active RFID is suggested in 2 different ways: 1) simplified tag collection and Ack procedure using query command and 2) modified Schoute's method to control the number of slots in the frame. To evaluate the performance of the improved system we develop the simulation model. Varying the number of tags in the system we track the performance measures such as throughput, recognition time for multi-tags and tag recognition rate during a given time. The suggested method shows the best performance over all measures. Simplification of collection and Ack commands using query commands contributes to reducing tag recognition time. And the modified Schoute's method which controls the frame size using $k_1$ and $k_2$ contributes to throughput improvement and reduces target cognition time by reducing the number of collection rounds.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6B
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• pp.544-552
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• 2003

This paper suggests an instruction code sufficiency algorithm preventing data collision when multiple transponders attempt to connect in the radio frequency identification system. Conventional time domain procedure generates unconditional collision. On the other hand, this algorithm prevents data collision by transmitting data when it meets instruction code. When multiple transponders are transmitting data coincidently, they exploit desired data with using difference of arrival time generated by recognition distance, respectively. As a result of simulation, utilizing the wireless recognition system, adopting the suggested algorithm, operating in 13.56MHz frequency band, it verify that there is Anti-collision and data loss by ensuring transmission time difference of one bit by adopting this algorithm.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2390-2392
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• 2003

ILC(Iterative Learning Control: 이하 ILC)는 현재 기계, 전기, 화학 등 많은 분야에 널리 적용되고 있다. ILC는 특히 반복적인 trajectory tracking Control 문제에 아주 효과적인 방법 중의 하나이다. 하지만 ILC는 메모리 기반의 scheme로서 trajectory tracking을 위해서는 많은 메모리를 요구하게 된다. 한편, 자세한 관찰에 의하면 인간의 팔, 다리 등의 관절의 움직임은 아주 정확하지가 않다. 이러한 사실로 미루어 인간이 정화한 모션을 취하는데 드는 비용을 줄이고자 모션 명령을 간단히 한다는 가정을 추론 해 낼 수 있다. 이러한 가정에 기초하여 우리는 ILC 명령을 간단히 하기 위해서 약간의 trajectory tracking의 정확성을 회생하는 메커니즘을 제안한다. 간단해진 ILC 명령은 적은 메모리 공간에 저장될 것이다. 또한, 로봇의 trajectory tracking을 위한 기존의 방법들은 아주 복잡할 뿐만 아니라 하나의 task의 수행만이 가능할 뿐 어떤 일반화의 방법도 제시하지 못하고 있다. 그래서 본 논문에서는 ILC 명령의 scaling에 대한 메커니즘을 제공하여 하나의 trajectory에 대해서 비슷한 모양이지만 다른 크기와 속도를 가지는 trajectory를 구현 할 수 있도록 하였다.