• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.237-245
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• 2012

This paper describes an acoustic echo canceller with double-talk by the blind signal separation. The acoustic echo canceller is deteriorated or diverged in the double-talk period. So we use the blind signal separation to estimate the near-end speech signal and to eliminate the estimated signal from the residual signal. The blind signal separation extracts the near-end signal with dual microphones by the iterative computations using the 2nd order statistical character. Because the mixture model of blind signal separation is multi-channel in the closed reverberation environment, we used the copied coefficients of echo canceller without computing the separation coefficients. By this method, the acoustic echo canceller operates irrespective of double-talking. We verified performances of the proposed acoustic echo canceller by simulations. The results show that the acoustic echo canceller with this algorithm detects the double-talk periods thoroughly, and then operates stably in the normal state without the divergence of coefficients after ending the double-talking. And it shows the ERLE of averagely 20dB higher than the normal LMS algorithm.

• Journal of Information Processing Systems
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• v.5 no.3
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• pp.151-158
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• 2009

This paper proposes a utility-based data rate allocation algorithm to provide high-quality mobile video streaming over femtocell networks. We first derive a utility function to calculate the optimal data rates for maximizing the aggregate utilities of all mobile users in the femtocell. The total sum of optimal data rates is limited by the link capacity of the backhaul connections. Furthermore, electromagnetic cross-talk poses a serious problem for the backhaul connections, and its influence passes on to mobile users, as well as causing data rate degradation in the femtocell networks. We also have studied a fixed margin iterative water-filling algorithm to achieve the target data rate of each backhaul connection as a counter-measure to the cross-talk problem. The results of our simulation show that the algorithm is capable of minimizing the transmission power of backhaul connections while guaranteeing a high overall quality of service for all users of the same binder. In particular, it can provide the target data rate required to maximize user satisfaction with the mobile video streaming service over the femtocell networks.

• Journal of Fashion Business
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• v.27 no.6
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• pp.110-123
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• 2023

As social distancing strengthened after the COVID-19 incident, people looked for things they could do alone. Additionally, as people have more financial resources, they purchase products they had previously considered purchasing, and the phenomenon of giving gifts to oneself has also appeared. Accordingly, this study analyzed fashion product reviews of KakaoTalk Gift, the service to exchange gift via SNS mobile app, to discover the phenomenon of self-gifting and the differences from interpersonal-gifting. For post-hoc data, in collected 18,354 pieces after excluding unnecessary data using a Python-based web crawling technique. The self-gifting behavior of KakaoTalk Gift different from the previous study for self-gift. Regardless of the gift-giving contexts, it determines that most self-gift products are material items. There are differences in product types and price levels when choosing gifts for others and oneself. As a self-gift, people typically buy luxury jewelry and branded bags/wallets to wear and show off. As interpersonal, among fashion products, people usually buy beauty products that reflect less personal tastes. When gift-giving to others, people buy products to appropriate prices to reduce the burden on both. When gift-giving to oneself, people buy wanted products regardless of the price. This study is significant because it suggests a new direction in self-gift research by limited online places to give gifts.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1546-1549
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• 2006

We have developed $EPLaR^{TM}$, a new way of making flexible electrophoretic displays. The TFTs have the same good performance, reliability and mature manufacturing processes as TFTs used in LCD monitors and LCD-TVs. We are working with partners to show that plastic displays can be made in existing TFT-LCD factories alongside glass LCDS. In this talk we describe the EPLaR process and show results for TFT arrays on plastic made in a factory by standard ${\alpha}$-Si TFT processing.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1527-1530
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• 2002

Video summary is one of the tools which can provide the fast and effective browsing fur a lengthy video. Video summary consists of many key-frames that could be defined differently depending on the video genre it belongs to. Consequently, the video summary constructed by the uniform manner might lead into inadequate result. Therefore, identifying the video genre is the important first step in generating the meaningful video summary. We propose a new method that can classify the genre of the video data in MPEG compressed bit-stream domain. Since the proposed method operates directly on the com- pressed bit-stream without decoding the frame, it has merits such as simple calculation and short processing time. In the proposed method, only the visual information is utilized through the spatial-temporal analysis to classify the video genre. Experiments are done for 6 genres of video: Cartoon, Commercial, Music Video, News, Sports, and Talk Show. Experimental result shows more than 90% of accuracy in genre classification for the well-structured video data such as Talk Show and Sports.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.780-783
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• 2004

The two-dimensional modeling of the non-stationary thermal state and voltage responsivity of the sensitive elements usually used in solid-state pyroelectric focal plane arrays are presented. Temperature distributions under periodical thermal excitation and the response of the thermal imaging device, which is composed of the pyroelectric sensitive elements mounted on a single silicon substrate, are numerically calculated. The sensitive element consists of a covering metal layer, infrared polymer absorber, front metal contact, sensitive pyroelectric element, the interconnecting column and the bulk silicon readout. The results of the numerical modeling show that the thermal crosstalk between sensitive elements to be critical especially at low frequency (f < 10Hz) of periodically modulated light. It is also shown that the use of our models gives the possibility to improve the design, operating regimes and sensitivity of the device.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.872-876
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• 2005

We propose a real-time post processing of nonlinear amplified signal to improve voice recognition in remote talk. In the previous research, we have found the nonlinear amplification has unique advantage for both the voice activity detection and the sound localization in remote talk. However, the original signal becomes distorted due to its nonlinear amplification and, as a result, the rest of sequence such as speech recognition show less satisfactorily results. To remedy this problem, we implement a linearization algorithm to recover the voice signal's linear characteristics after the localization has been done.

• The Journal of the Acoustical Society of Korea
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• v.27 no.1E
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• pp.17-24
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• 2008

Blind speech separation (BSS) is well-known as a powerful technique for speech enhancement in many real world environments. In this paper, we propose a new application of BSS - acoustic echo cancellation (AEC) in a car environment. For this purpose, we develop a block-online BSS algorithm which provides robust separation than a batch version in changing environments with moving speakers. Simulation results using real world recordings show that the block-online BSS algorithm is very robust to speaker movement. When combined with AEC, simulation results using real audio recording in a car confirm the expectation that BSS improves double talk detection and echo suppression.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2019-2021
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• 1999

In this paper, the AC-PDP's structural defects with a gap between front and rear glass are investigated. Breakdown voltage, sustain voltage, current and brightness have been measured for various gaps between two plates under various gas pressures. The experimental results show that the firing voltage, sustain voltage and brightness were decreased whereas the discharge current was increased as the gap increased. When the gap is over $40{\mu}m$, it was impossible to drive cells separately.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.28-28
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• 2014

Type Ia supernovae (SNe Ia) have provided the first evidence that the Universe is accelerating. Nevertheless, the nature of the progenitors has remained a mystery, indeed controversial. In this talk I will first summarize the main supernova explosion mechanisms and the observational classification of supernovae. I will show how SNe Ia can be used as standardizable distance candles and discuss possible limitations of the method. In the main part of the talk I will discuss the main progenitor models that have been proposed, emphasizing the problems and advantages of each, and how they can be observationally tested. I will then present some relatively recent discoveries by the Palomar Transient Factory and most recently in M82 that directly constrain the progenitors in a few cases.