• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.1938-1945
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• 2008

Due to rapid economic growth, the usage of residential cooling electrical appliances such as air conditioners and refrigerators has increased dramatically for the last decades. In other to reduce its energy consumption, the authorities have applied energy efficiency standards for principal appliances, including refrigerator. This paper estimates the distribution of refrigerators using the Bass Diffusion Model and then performs economic analysis corresponding to enhancement of energy efficiency more correctly than existing methods.

• Journal of Broadcast Engineering
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• v.21 no.6
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• pp.889-898
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• 2016

Virtual Bass System (VBS) is widely used to extend the lower frequency limit of small loudspeakers, which generates harmonics of a fundamental frequency. The perceptual quality of the VBS is highly dependent on the harmonic weighting strategy. There have been several weighting methods, including exponential attenuation and timbre matching. However, it is essential to match phases between harmonics in the original signal and generate harmonics to precisely convey the weighting strategy. This paper shows the limitations of the previous harmonic weighting schemes and proposes a new harmonic weighting scheme. The proposed weighting scheme proposes phase matching between the original and generated harmonics and varies the slope of the attenuation weighting dynamically according to the missing fundamental frequency. Objective and subjective tests show that the proposed harmonic weighting scheme provides more natural and effective bass perception in a limited situation than the conventional schemes, which implies that the phase matching is essential for the high quality bass enhancement.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.360-365
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• 2019

A polyvinylidene fluoride (PVDF)-based film speaker is successfully fabricated with enhanced bass sound by incorporating buckled nanospring carbon nanotubes (NS-CNTs) as fillers. Various concentrations up to 1-7 wt% of uniformly dispersed buckled NS-CNTs are loaded to increase the beta (β)-phase fraction, crystallinity, and dielectric constant of the speaker, and this results in the bass part enhancement of about 19 dB full scale (dBFS) at 7 wt% filler loading of the piezoelectric film speaker.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.433-433
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• 2006

• IE interfaces
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• v.9 no.3
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• pp.44-51
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• 1996

The purpose of this paper is to develop a modeling framework for analyzing the effect of price on the PCS (Personal Commununications Service) demand. To achieve this aim, a nonlinear regression model was derived to capture the income effect on the PCS demand and then was combined into an integrated Bass diffusion model. The model was then applied to the emerging PCS market in Korea and the market demands up to the year 2006 were estimated. The results were reviewed and evaluated in various aspects. Finally, the possibilities of model enhancement and model extensions were explored.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.566-573
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• 2003

This study was performed to manufacture a rigid sound absorbing material by increasing the continuous void ratio of cellular concrete, thereby achieving an increase in sound absorption ratio and an enhancement in strength of the cellular concrete. By the experiments, it was determined that an increase in sound absorption ratio is achieved by increasing the added amount of air voids, thereby increasing the continuous void ratio. When the material had a thickness of 5 cm, a satisfactory average sound absorption ratio of 70% was obtained at a continuous void ratio of 40% or more. An increase in the thickness of the sound absorbing material resulted in an increase in sound absorption ratio in a super bass range. The specific gravity of cellular concrete meeting an average sound absorption ratio of 70% was 0.4 at a material thickness of 5 cm, and 0.6 or less at a material thickness of 7 cm. The compressive strength of the cellular concrete having a specific gravity of 0.4 meeting an average sound absorption ratio of 70% or more was 1.37 Mpa at a cement fineness of 3,000. This compressive strength was increased to 3.34 MPa at a cement fineness of 8,000. Accordingly, it was determined that the compressive strength of cellular concrete having continuous voids increases with a higher cement fineness.