• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.22.1-22
• /
• 2001

In this paper we present Multiple-Channel Active Noise Control[ANC] system by employing Independent Component Analysis[ICA] and Adaptive Network Fuzzy Inference System[ANFIS]. ICA is widely used in signal processing and communication and it use prewhiting and appropriate choice of non-linearities, ICA can separate mixed signal. ANFIS controller is trained with the hybrid learning algorithm to optimize its parameters for adaptively canceling noise. This new method which minimizes a statistical dependency of mutual information(MI) in mixed low frequency noise signal and there is no need to secondary path modeling. The proposed implementations achieve more powerful and stable noise reduction than Filtered-X LMS algorithms which is needed for LTI assumption and precise secondary error

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.4
• /
• pp.152-159
• /
• 2005

The method of induction noise reduction can be classified by using passive control or active control method. However, the passive control method has a demerit to reduce the effect of noise reduction to low frequency (below) 500Hz) range and to be limited in a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used in LMS (Least-Mean-Square) algorithm because it can obtain the complex transfer function easily in real-time. Especially, Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm could not match if the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. So, in order to solve the problem in this study, the Moving Bandpass Filter(MBPF) was proposed and implemented. The ANC using MBPF for the reduction of the induction noise shows that more noise reduction as 4dB than without MBPF.

• Digital Contents
• /
• no.10 s.77
• /
• pp.38-44
• /
• 1999

인터넷 사용인구의 증가와 사용 용도의 다양화로 인해서 초기 웹의 정적이고 단순함은 더 이상 사용자의 욕구를 충족 시킬 수 없었다. 이러한 욕구는 웹 페이지가 동적이며 더욱 다양한 기능을 갖도록 요구하였으며 자바, Active-X Control 등의 기술을 이용한 Executable Content가 등장하게 되었다. 그러나 이것은 내부 정보 유출 및 파일 삭제 등의 컴퓨터자원에 대한 불법적인 접근의 위험성이 증가하고 있다. 이런 보안상의 취약점에 대해 살펴본다.

• The Journal of the Acoustical Society of Korea
• /
• v.33 no.5
• /
• pp.309-315
• /
• 2014

In this paper, a novel variable step-size filtered-x gradient adaptive lattice (NVSS-FxGAL) algorithm for active noise control system is proposed. The gradient adaptive lattice (GAL) algorithm is capable of controlling the narrow band noise effectively. The GAL algorithm can achieve both fast convergence rate and low steady-state level using the variable step-size. However, it suffers from the convergence performance for varying signal characteristic since the global variable step-size is equally applied to all lattice stages. Therefore, the proposed algorithm guarantees the stable and consistency convergence performance by using the local variable step-size for the suitable each lattice stage. Simulation results confirm that the proposed algorithm can obtain the fast convergence rate and low steady-state level compared to the conventional algorithms.

• The Journal of the Acoustical Society of Korea
• /
• v.34 no.5
• /
• pp.377-384
• /
• 2015

An active noise control (ANC) algorithm for noise canceling headphone is proposed. In this study, the feedback ANC operated with the filtered-x least mean square algorithm (FxLMS) algorithm is used to attenuate the undesired noise. Also an adaptive residual music canceller (RMC) is proposed for enhancing the accuracy of the reference signal of the feedback ANC. Simulation results show that a high quality of music sound can be consistently achieved in a time-varying secondary path situation.

• Journal of the Korea Computer Industry Society
• /
• v.3 no.3
• /
• pp.283-294
• /
• 2002

Now is the time for web-based video e-mail system because of world wide use of internet. But video data is so large, then data compression is much needed for transmission by web. In this paper, my colleagues and I implement full motion video e-mail system using MPEG-4, the international standards for audio-visual data. This video e-mail system is made of web-based active-X control, so easily accessible by web, and applies real-time audio-video compression. It's possible for everyone to send video e-mail for free to everywhere in the world if this system is used. The main application areas of this system are multimedia mailing service, web-based video advertisement, remote education, remote medical service and shopping mall construction, etc.

• International Journal of Automotive Technology
• /
• v.7 no.7
• /
• pp.777-784
• /
• 2006

The lateral dynamic behaviours of a track inspection vehicle with laterally guided system are studied for the safety and comfort. A 10-DOF dynamic model is proposed counting for lateral and yaw motions. The equations for motions of the vehicle running on curved tracks at a constant speed are presented. It is shown by simulation that lateral guiding forces applied to the guiding wheels on the inner side of the track increase in a larger scale in comparison with those on the outer side when the vehicle passes through curved tracks with cant, and the front guiding spring forces is larger than the rears. Lateral vibrations due to yaw motions of the vehicle take place when the vehicle runs through curved tracks. Finally, effect of the lateral guidance on the vehicle dynamics is also examined and advantages of such a guiding system are discussed in some details. An optimal guided control is applied to restrain the lateral and yaw motions. The comparisons between the active and passive guidance explain the effect of the active control approaches.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.6C
• /
• pp.343-348
• /
• 2011

This paper introduces a design for real time wireless headset using ANC (active noise control) system based on NFxLMS adaptive filter algorithm. The training time of the proposed system is significantly reduced by using the RMS delay spread of a channel as an error correction parameter, and convergence rate of the FxLMS filter has been improved with updating the coefficients of the NFxLMS filter, which we have got during the training process. Our system has shorter training time and better convergence rate at the same noise reduction level than the conventional system under real noisy environment.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.1
• /
• pp.133-141
• /
• 2020

PURPOSE: This study examined the effects of active release technique on pain, Oswestry Disability Index, and pelvic asymmetry in chronic low back pain patients. METHODS: Thirty five outpatients diagnosed with chronic low back pain were enrolled in this study. The patients were divided randomly into an active release technique therapy group(experimental group; n=18) and myofascial release technique therapy group(control group; n=17). These groups performed their respective therapy for a 40-minute session occurring twice a week over six weeks. The Visual Analogue Scale(VAS) was used to measure the subjects' pain, and the Korean Oswestry Disability Index(KODI) was used to measure the subjects' dysfunction. To assess the patients' pelvic asymmetry, their pelvic tilt and pelvic rotation were measured using X-ray imaging. RESULTS: Both the experimental group and control group exhibited significant decreases in their VAS and KODI scores after the therapy(p<.05). The experimental group exhibited a significant decrease in their pelvic tilt and pelvic rotation after therapy(p<.05). A significant difference was observed between the experimental group and the control group (p<.05). CONCLUSION: These results suggest that active release technique is effective in decreasing the level of pain and dysfunction in chronic low back pain patients. In addition, the active release technique is considered to be more effective in improving the pelvic tilt and pelvic rotation than myofascial release technique. This can be an effective method for the non-pharmacological and non-surgical treatment of chronic low back pain.

• Advances in Energy Research
• /
• v.3 no.2
• /
• pp.81-95
• /
• 2015

Microgrid, which can be considered as an integration of various dispersed resources (DRs), is characterized by number of DRs interfaced through the power electronics converters. The microgrid comprising these DRs is often operated in an islanded mode. To minimize the cost, reduce complexity and increase reliability, it is preferred to avoid any communication channel between them. Consequently, the droop control method is traditionally adopted to distribute active and reactive power among the DRs operating in parallel. However, the accuracy of distribution of active and reactive power among the DRs controlled by the conventional droop control approach is highly dependent on the value of line impedance, R/X i.e., resistance to reactance ratio of the line, voltage setting of inverters etc. The limitations of the conventional droop control approach are demonstrated and a modified droop control approach to reduce the effect of impedance mis-match and improve the time response is proposed. The error in reactive power sharing is minimized by inserting virtual impedance in line with the inverters to remove the mis-match in impedance. The improved time response is achieved by modifying the real-power frequency droop using arctan function. Simulations results are presented to validate the effectiveness of the control approach.