• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.185-190
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• 2015

The purpose of this study is developing the quantify the seat belt pulling Noise index and evaluation method. This paper presents the objective method to evaluate the emotional feeling about the pulling Noise of the seat belt. The physical quantification is required to objectively evaluate the emotional feeling of the pulling Noise. This is called the "Noise metric." The Noise metric is should correlated to the subjective rating of the pulling Noise. The pulling Noise index is developed throughout the linear regression of the Noise metric and the subjective rating. The developed index is used for the objective evaluation of the emotional feeling about the pulling Noise of a seat belt throughout the modification of seat belt components.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.8
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• pp.375-377
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• 2006

An adaptive IIR filter in ANC(Active Noise Control) systems is more effective than an adaptive FIR filter when acoustic feedback exists, in which cause an order of an adaptive FIR filter must be very large if some of poles of the ideal control filter are near the unit circle. But the IIR filters may have stability problems especially when the adaptive algorithm for adaptive filters is not yet converged. In this paper, a stabilized multi-channel recursive LMS (MCRLMS) algorithm for an adaptive multi-channel IIR filter is presented. RLMS algorithms usually diverge before the algorithm is not yet converged. So, in the beginning of the ANC system, the stability of the RLMS algorithms could be improved by pulling the poles of the IIR filter to the center of the unit circle, and returning the poles to their original positions after the filter converges. Computer simulations and experiments for dipole ducts using a TMS320C32 digital signal processor have performed to show the effectiveness of a proposed algorithm.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.30-32
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• 2006

An adaptive IIR filter in ANC(Active Noise Control) systems is more effective than an adaptive FIR filter when acoustic feedback exists, in which cause an order of an adaptive FIR filter must be very large if some of poles of the ideal control filter are near the unit circle. But the IIR filters may have stability problems especially when the adaptive algorithm for adaptive filters is not yet converged. In this paper, a stabilized multi-channel recursive LMS (MCRLMS) algorithm for an adaptive multi-channel IIR filter is presented. RLMS algorithms usually diverge before the algorithm is not yet converged. So, in the beginning of the ANC system, the stability of the RLMS algorithms could be Improved by pulling the poles of the IIR filter to the center of the unit circle, and returning the poles to their original positions after the filter converges. Computer simulations and experiments for dipole ducts using a TMS320C32 digital signal processor have performed to show the effectiveness of a proposed algorithm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.112-118
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• 2002

The adaptive m filters is more effective than m filters when acoustic feedback exists, in which cause an order of a FIR filter must be very large if some of poles of the ideal control filter are near the unit circle. But the IIR filters may have stability problems especially when the adaptive algorithm is not converged. In this paper, a stabilizing procedure for adaptive IIR filters is proposed. In the beginning of the ANC system, it improve a stability by pulling the poles of the IIR filter to the center of the unit circle, and it returns the poles to their original positions after the filter converge. Computer simulations and experiments are performed to show the effectiveness of proposed schemes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.99-106
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• 2006

In this paper, implementation of active mufflers using multiple channel adaptive IIR filter is presented. Usually, recursive LMS(RLMS) algorithms for adaptive IIR filters are highly efficient than filtered-X LMS(FXLMS) algorithms, when the order of both algorithms are the same. However, RLMS algorithms usually diverge before the algorithms arenot yet converged. So, the prefilters are presented to improve the stability by pulling the poles of feedback control transfer function in the beginning of active noise control and returning the original poles after the filters converge. The engine noises of diesel engine automobiles and gasoline engine automobiles are analyzed and the mathematical model of an active muffler is derived. Computer simulations and experiments are performed to show the effectiveness of the proposed systems.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.5
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• pp.889-895
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• 2008

In this paper a Fractional-N frequency synthesizer is designed for UHF RFID readers. It satisfies the ISO/IEC frequency band($860{\sim}960MHz$) and is also applicable to mobile RFID readers. A VCO is designed to operate at 1.8GHz band such that the LO pulling effect is minimized. The 900MHz differential I/Q LO signals are obtained by dividing the differential signal from an integrated 1.8GHz VCO. It is designed using a $0.18{\mu}m$ RF CMOS process. The measured results show that the designed circuit has a phase noise of -103dBc/Hz at 100KHz offset and consumes 9mA from a 1.8V supply. The channel switching time of $10{\mu}s$ over 5MHz transition have been achieved, and the chip size including PADs is $1.8{\times}0.99mm^2$.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.191-192
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• 2007

This paper presents a 900MHz fractional-N frequency synthesizer for radio frequency identification (RFID) reader using $0.18{\mu}m$ standard CMOS process. The IC meets the EPC Class-1 Generation-2 and ISO-18000 Type-C standards. To minimize VCO pulling, the 900MHz VCO is generated by a 1.8GHz VCO followed by a frequency divider. The settling time of the synthesizer is less than $20{\mu}m$. The frequency synthesizer achieves the phase noise of -105.6dBc/Hz at 200kHz offset. The frequency synthesizer occupies an area of $1.8{\times}0.99mm^2$, and dissipates 8mA from a low supply voltage of 1.8V.

• Asian Oncology Nursing
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• v.9 no.1
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• pp.31-42
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• 2009

Purpose: The purpose of the study was to understand how patients experience everyday life in an isolation unit for hematopoietic stem cell transplantation (HSCT). Method: The data were collected from 25 patients with HSCT at the isolation unit from January to March in 2008 in one general hospital in Korea. The data were collected by participant observations and ethnographic interviews and were analyzed using ethnographic method. Results: Four themes regarding environmental area emerged: 'barrier pulling up the drawbridge', 'very strange world', 'small and restricted space tied by IV and other treatment lines', and 'loud noise in a silent space.' Three themes regarding patients emerged: 'facing fear and anxiety', 'continuation of loneliness and lethargy', and 'compromising with a very long, dull, and boring time'. These themes describe how patients with HSCT suffer from continuous physical and psychosocial problems in a confined space, while endeavoring to control these problems and to search for hope for a new life. Conclusion: The results of the study provide an in-depth understanding of the experience and culture of patients in an isolation unit for HSCT. They would be used in developing practical programs to decrease patient's culture shock including fear and anxiety at isolation unit for HSCT.

• Journal of IKEEE
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• v.14 no.1
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• pp.65-74
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• 2010

The Digital TV(DTV) standard has ushered in a new era in TV broadcasting and raised a great demand for DTV tuners. There are many challenges in designing a DTV tuner, of which the most difficult part is the frequency synthesizer. This paper presents the design of a frequency synthesizer for DTV Tuners in a $0.18{\mu}m$ CMOS process. It satisfies the DTV(ATSC) frequency band(54~806MHz). A scheme is proposed to cover the full band using only one VCO. The VCO has been designed to operate at 1.6~3.6GHz band such that the LO pulling effect is minimized, and reliable broadband characteristics have been achieved by reducing the variations of VCO gain and frequency step. The simulation results show that the designed VCO has gains of 59~94MHz(${\pm}$17.7MHz/V,${\pm}$23%) and frequency steps of 26~42.5MHz(${\pm}$8.25MHz/V,${\pm}$24%), and a very wide tuning range of 76.9%. The designed frequency synthesizer has a phase noise of -106dBc/Hz at 100kHz offset, and the lock time is less than $10{\mu}$sec. It consumes 20~23mA from a 1.8V supply, and the chip size including PADs is 2.0mm${\times}$1.8mm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.570-575
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• 2019

Active muffler is implemented by applying active noise control technique to reduce exhaust noise of automobile muffler. Conventional Filtered_x LMS algorithm has a problem that the degree of control filter becomes very large and convergence deteriorates when acoustic feedback is present. The recursive LMS algorithm can compensate for this problem because it can be easily diverted in the adaptive filter adaptation process. In this paper, the structure of the primary path and the secondary path transfer function is designed as the IIR filter to improve the convergence performance and the computational burden, and the stabilization filter algorithm is applied to secure stability which is a disadvantage of the IIR filter structure. The stabilization filter algorithm plays a role of pulling the pole into the unit circle to prevent the pole of the transfer function corresponding to the acoustic feedback from diverging during the adaptation process. In this way, the computational burden of the active muffler system and the convergence performance can be improved. In order to show the usefulness of the proposed system, we compared the performance of the proposed Filtered_x LMS algorithm with the performance of the proposed system for the exhaust sound of a diesel engine, which is a variable environment. Compared to conventional algorithm, proposed algorithm's computational burden is less than half, and convergence performances are more than 4 times.