• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1685-1686
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• 2008

This paper presents the design and experiment results of a multi-layered microsystem for magnetic bead applications. The magneto-microfluidic device is designed for capable of separating magnetic beads. In the presence of the magnetic field, magnetic beads are attracted and moved to high gradient magnetic fields. A multi-layered microfluidic channel consists of top and bottom layers in order to separate magnetic beads in the vertical direction. Our channel is easily integrated magnetic cell sorter, especially on-chip microelectromagnet or permanent magnet device. Fast separation of magnetic beads in top and bottom channels can be used in high throughput screening to monitor the efficiency of blood and drug compounds.

• Journal of KSNVE
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• v.9 no.6
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• pp.1137-1144
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• 1999

Most of ANC(active noise control) researches are focused on adaptive algorithms, computer simulations and implementations of single-channel system in experimental environments. In this paper, a multi-channel ANC system based on DSP's was developed to obtain global attenuations over wide region and applied to the active control of the humming noise generated by a transformer. The developed ANC system including 24 microphones and 12 spearkers was applied to the real transformer noise reduction problem. Results showed that the control system could successfully control the humming noise over the region of interest.

• Proceedings of the IEEK Conference
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• summer
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• pp.27-30
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• 2004

OFDMA is considered as one of the major candidates for broadband wireless access. The OFDMA signal is usually coherently demodulated, requiring the channel estimation which can be estimated using a known pilot signal. In multi-cell environment, the performance of channel estimation is mainly limited by intercell interference. It is desirable to use a pilot signal that can estimate the channel information robust to the intercell interference in the OFDMA uplink system. In this paper, we consider two types of pilot signal applicable to multi-cell OFDMA uplink systems: One is time-multiplexed pilot signal and the other is code­multiplexed pilot signal. Simulation results show that the code-multiplexed pilot is suitable for low mobility environment and time-multiplexed pilot is suitable for high mobility environment.

• The Journal of the Korea institute of electronic communication sciences
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• v.4 no.1
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• pp.33-36
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• 2009

Incremental converters provide a solution for such measurement applications, as they retain most of the advantages of conventional ${\Delta}{\Sigma}$ converters, and yet they are capable of offset-free and accurate conversion. Most of the previous research on incremental converters was for single-channel and dc signal applications, where they can perform extremely accurate data conversion with more than 20-bit resolution. In this paper, a design technique for implementing multi-channel incremental data converters to convert narrow bandwidth ac signals is discussed. It incorporates the operation principle, topology, and digital decimation filter design. The theoretical results are verified by simulation results.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.216-219
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• 2003

In this paper, we present performance analysis of an IEEE P802.15.3a high rate wireless personal area network transceiver. This physical layer standard uses QOSK as its sub-channel modulation scheme and orthogonal frequency domain modulation (OFDM) for sub-bands. OFDM is used for each sub-band so that multi-path effects are absorbed by equalizer and guard, and fading can be approximately modeled as additive white Gaussian noise. In multi-band ultra-wideband system, DAC quantization error is important noise source since high resolution conversion cannot be used due to high power consumption. Simulation result shows that, to get 640-Mbps throughput, at least 5-bits precision is necessary to maintain bit-error rate under 10$\^$-2/, which can be lowered, with channel coding, to 10$\^$-6/ that is the bit-error rate required by IEEE 802.15 upper protocol layer, in 4-meter LOS fading channel.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.280-282
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• 2005

급변하는 컴퓨터 네트워킹 환경에서 이동화에 따른 무선통신의 비중이 날로 더해지고 있다. 본 논문에서는 무선 인터넷 프로토콜 표준인 IEEE 802.11의 문제점들을 분석하고, Multi-Hop Ad Hoc Network에서 성능 향상을 위하여 Single-channel Jamming 신호를 기반으로 한 SJMAC(Single-channel Jamming MAC) 프로토콜을 설계하고, NS2 모듈을 구현한 후에 성능 평가를 하였다. 기존 IEEE 802.11과의 성능 비교를 위하여 NS2 (Network Simulator2)[1]에 SJMAC 모듈을 추가하여 제안된 프로토콜의 성능을 검증한다.

• 한국해양학회지
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• v.30 no.2
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• pp.116-124
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• 1995

Marine, shallow seismic data have been acquired and processed by newly developed multi-channel(6 channel), PC-based digital recording and processing system. The digital processing system includes pre-processing, swell-compensation filter, frequency filter, gain correction, deconvolution, stacking, migration, and plotting. The quality of processed sections is greatly enhanced in terms of signal-to-noise ratio and vertical/horizontal resolution. The multi-channel, digital recording, acquisition and processing system proved to be and economical, efficient and easy-to-use marine shallow seismic tool.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.677-687
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• 2016

Multi-way relay networks (MWRNs) allow multiple users to exchange information with each other through a single relay terminal. MWRNs are often incorporated with capacity achieving lattice codes to enable the benefits of high-rate signal constellations to be extracted. In this paper, we analytically characterize the symbol error rate (SER) performance of a functional decode and forward (FDF) MWRN in the presence of channel estimation errors. Considering M-ary quadrature amplitude modulation (QAM) with square constellations as an important special case of lattice codes, we obtain asymptotic expressions for the average SER for a user in FDF MWRN. The accuracy of the analysis at high signal-to-noise ratio is validated by comparison with the simulation results. The analysis shows that when a user decodes other users with better channel conditions than itself, the decoding user experiences better error performance. The analytical results allow system designers to accurately assess the non-trivial impact of channel estimation errors and the users' channel conditions on the SER performance of a FDF MWRN with M-QAM modulation.

• Knowledge Management Research
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• v.17 no.3
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• pp.45-64
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• 2016

As the digital retail environement becomes prevalent, consumers are given greater opportunities to make purchases across physical and digital boundaries. Prior research emphasizes that the attractiveness of the digital or online channel is relatively determined by spatial specifics of physical locations. The overall market trend combined with prior research suggests that understanding spatial specifics becomes a key to managing both offline and online sales performance together. In this study, we focus on geographic variation in sales performance through offline and online channels and aim to investigate the channel-level sales difference between central and subsidiary areas. To this end, we obtain sales data of skincare and makeup products from a leading cosmetic company. Next, we examine spatial autocorrelations in data and then employ the spatial error models to study the effects of spatial specifics. The empirical findings are as follows. First, there are significant differences in category-specific and channel-level sales between central and subsidiary areas. Second, Moran's I statistics demonstrate the spatial autocorrelations of each variable. Third, spatial error models outperform simple regression models with lower AIC values. Finally, spatial specifics play a greater role in understanding online sales in subsidiary areas whereas they exert greater influence on offline sales in central areas. We believe our study advances the related theory and knowledge of multi-channel retailing and also contributes practically to location-dependent multi-channel strategies and sales data analytics.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.150-157
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• 2009

In this paper, we propose a person tracking based multi-channel audio panning system for multi-view broadcasting services. Multi-view broadcasting is to render the video sequences that are captured from a set of cameras based on different viewpoints, and multi-channel audio panning techniques are necessary for audio rendering in these services. In order to apply such a realistic audio technique to this multi-view broadcasting service, person tracking techniques which are to estimate the position of users are also necessary. For these reasons, proposed methods are composed of two parts. The first part is a person tracking method by using ultrasonic satellites and receiver. We could obtain user's coordinates of high resolution and short duration about 10 mm and 150 ms. The second part is MPEG Surround parameter-based multi-channel audio panning method. It is a method to obtain panned multi-channel audio by controlling the MPEG Surround spatial parameters. A MUSHRA test is conducted to objectively evaluate the perceptual quality and measure localization performance using a dummy head. From the experiments, it is shown that the proposed method provides better perceptual quality and localization performance than the conventional parameter-based audio panning method. In addition, we implement the prototype of person tracking based multi-view broadcasting system by integrating proposed methods with multi-view display system.