• 한국정보전자통신기술학회논문지
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• 제16권5호
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• pp.315-324
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• 2023

본 논문에서는 UKF(unscented Kalman filter)와 연동된 입자필터를 이용한 단안시 카메라의 실시간 자세추정 기법을 제안한다. 단안시 카메라 자세 추정 기법에는 주로 카메라 영상과 자이로스코프, 가속도센서 데이터 등을 연동하는 방법이 많이 이용되고 있으나 본 논문에서 제안하는 방법은 별도의 센서 없이 카메라 영상에서 취득되는 2차원 시각 정보만을 이용하는 것을 목표로 한다. 제안된 방법은 카메라 영상 이외의 부가적인 장비를 이용하지 않고 별도의 센싱 정보 없이 2차원 영상만으로 카메라 추적이 가능하며, 따라서 기존에 비해 하드웨어 구성이 단순해질수 있다는 장점을 갖고 있다. 제안된 방법은 UKF와 연동된 입자필터를 기반으로 한다. 입자필터의 각 입자마다 개별적으로 정의된 UKF로부터 카메라의 상태를 추정한 다음 입자필터의 전체 입자로부터 카메라 상태에 대한 통계데이터를 산출하고 이로부터 카메라의 실시간 자세정보를 계산한다. 기존의 방법과 달리 제안된 방법은 카메라의 급격한 흔들림이 발생하는 경우에도 카메라 추적이 가능함을 보여주며, 영상 내의 특징점 대다수가 가려지는 환경에서도 카메라 추적에 실패하지 않음을 실험을 통하여 확인하였다. 또한 입자의 개수가 35개인 경우 프레임 당 소요 시간이 약 25ms이며 이로부터 실시간 처리에 문제가 없음을 확인할 수 있었다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 1호
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• pp.357-360
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• 1998

DS/CDMA system rejected narrow-band interference and additional White Gaussian noise which are occured at multipath, intentional jammer and multiuser to share same bandwidth in mobile communication systems. Because of having not sufficiently obtained processing gain which is related to system performance, they were not effectively suppressed. In this paper, an matched filter channel model using backpropagation neural network based on complex multilayer perceptron is presented for suppressing interference of narrow-band of direct sequence spread spectrum receiver in DS/CDMA mobile communication systems. Recursive least square backpropagation algorithm with backpropagation error is used for fast convergence and better performance in matched filter receiver scheme. According to signal noise ratio and transmission power ratio, computer simulation results show that bit error ratio of matched filter using backpropagation neural network improved than that of RAKE receiver of direct sequence spread spectrum considering of con-channel and narrow-band interference.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.112-115
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• 2010

The heart rate is the most important vital sign in diagnosing heart status. The simple method to measure the heart rate in the mobile healthcare device is using the PPG signal. In developing the mobile healthcare device using the PPG signal, the most important issue is the inaccuracy of the measured heart rate because the PPG signal is distorted from the user's motions. To improve the problem, this study proposed the new method that is to estimate the heart rate without an additional sensor in real life. The proposed method in this study is using the histogram filter. In order to evaluate the performance of the proposed method, the study compares its results with the moving average method in motion environment. According to the experimental results, the performance of the proposed method was more than 40% better than the performances of the MAF.

• 로봇학회논문지
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• 제7권4호
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• pp.276-283
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• 2012

Due to the low localization accuracy and the requirement of special infrastructure, current LBS(Localization Based Service) is limited to show P.O.I.(Point of Interest) nearby. Improvement of IMU(Inertial Measurement Unit) based deadreckoning is presented in this paper. Additional sensors such as the magnetic compass and magnetic flux sensors are used as well as the accelerometer and the gyro for getting more information of movement. Based on the pedestrian movement, appropriate sensor information is selected and the complementary filter is used in order to enhance the accuracy of the localization.

• 한국연소학회지
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• 제15권3호
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• pp.25-31
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• 2010

Combined technique of burner and DOC has been used for regeneration of Diesel Particulate Filter. Experiments has been performed to increase the temperature of engine exhaust gas to burn the collected soot in DPF at all conditions of operation of 3 liter diesel engine. Ignition temperature of soot can be successfully obtained by heats of burner flame and residual fuel oxidation at diesel oxidation catalyst even in the condition of oxygen deficiency. It is found that the load of air compressor and heat loss can be reduced to the level of practical application. It is also found that CO and THC emissions are not increase by additional combustion of regeneration burner.

• 한국통신학회논문지
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• 제9권2호
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• pp.62-69
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• 1984

DS대역확산 통신 수신기의 성능은 디지털 백색화 여파기를 사용하여 개선시킬 수 있다. 본 연구에서는 출력의 hard-limiter에서 검출한 신호를 입력으로 궤환시켜 간섭과 잡음성분만을 백색화하는 디지털 궤환 백색화 여파기를 제안하고 여파기의 계수계산 방법에 관하여 기술하였다. SNR과 BER에 관한 식을 유도하였으며 종래의 디지털 백색화 여파기와 비교하였다. 컴퓨터 시뮬레이션 결과 오율특성은 종래의 방식에 비해 크게 향상된 것으로 나타났다.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.253-261
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• 2004

A simple and effective filtering method to control the member size of an optimized structure is proposed for topology optimization. In the present approach, the original objective sensitivities are replaced with their relative values evaluated within a filtering area. By adjusting the size of the filtering area, the member size of an optimized structure or the level of its topological complexity can be controlled even within a given finite element mesh. In contrast to the checkerboard-free filter, the present filter focuses on high-frequency components of the sensitivities. Since the present filtering method does not add a penalty term to the objective function nor require additional constraints, it is not only efficient but also simple to implement. Mean compliance minimization and eigenfrequency maximization problems are considered to verify the effectiveness of the present approach.

• 제어로봇시스템학회논문지
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• 제12권7호
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• pp.637-643
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• 2006

Generally, the tracking performance of optical disk drive(ODD) system can be improved using a disturbance observer(DOB). However, a DOB is not easily applied in an ODD system because an additional microprocessor, such as a digital signal processor(DSP), is needed. This paper shows how a DOB system can be replaced by the error-based modified disturbance observer(EM-DOB) when two mathematical conditions are satisfied. Due to the simplified structure of EM-DOB, the algorithm is easily implemented as an analog circuit, which is suitable for the ODD servo system. Additionally, in these algorithms, disturbances rejection performances can be tuned as Q filter parameters. Similar to a DOB system, three design guidelines of a Q filter can be applied. Experimental results of DOB and EM-DOB are evaluated under forced disturbances.

• 전기학회논문지
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• 제56권2호
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• pp.383-388
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• 2007

This paper considers a low-order dynamic output feedback controller design problem. Since the proposed control law inherently has a low-pass filter property, it can alleviate the mal-effects of the sensor noise without additional filter designs. Frequency domain analysis shows the characteristics of the proposed control law against measurement noise. The effectiveness of the proposed control law is illustrated by numerical simulations with a rotary inverted pendulum and a convey-crane. Using only one integrator the proposed control law has the advantage to the stabilization problem with sensor noise as well as it can successfully replace the measurements of derivative terms in a state feedback control law.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.634-637
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• 2008

A large eddy simulation with an explicit filter on unstructured mesh is presented. The flow filed is semi-implicitly marched by a fractional step method. Spatial discretization of the solver is designed to guarantee the second order accuracy. An isotropic explicit filter is adopted for measuring the level of subgrid scale velocity fluctuation. The filter is linearity-preserving and has second order commutation error. The developed subgrid scale model is basically eddy viscosity model which depends on the explicitly filtered fields and needs no additional ad hoc wall treatment, such as van Driest damping function. For the validation, the flows in a channel and a pipe are calculated and compared to experimental data and numerical results in the literature.