• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.85-88
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• 2001

In this paper we consider a problem of blind co-channel signal separation, the goal of which is to estimate multiple co-channel digitally modulated signals using an antenna array. We employ the joint maximum likelihood estimation and present a sequential algorithm, which is referred to as sequential joint maximum likelihood (SJML) algorithm. It separates multiple co-channel signal on-line and converges fast in overdetermined noisy communication environment. And the computational complexity of SJML for M-QAM (M=8, 16, 64,...) signals is less expensive compared to the SLSP. Useful behavior of this algorithm are confirmed by simulations.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.390-391
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• 2008

대용량의 이동 고속통신 환경 하 에서 다중경로 페이딩에 의한 성능열화 영향을 효과적으로 줄이고, 용량을 극대화하기 위해 MIMO(Multi-Input Multi-Output) 와 OFDM (Orthogonal Frequency Division Multiplexing) 기술들이 차세대 이동통신시스템으로 최근에 각광을 받고 있다. 그러나 cellular 시스템에서는 Co-Channel Interference의 영향을 피할 수도 없으며, 그 영향 또한 그 무엇보다도 크다. 그러므로 본 논문에서는 이러한 MIMO OFDM 시스템의 Co-Channel Interference 의 영향을 줄이고 성능 향상을 위해 Interference Cancelling 기법을 응용한 STBC-OFDM 시스템의 성능을 MATLAB simulation을 통해 기술하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.145-148
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• 2007

The authors report on the fabrication of thin film transistors (TFTs) that use amorphous indium-gallium-zinc oxide (a-IGZO) channel and have the channel length (L) and width (W) patterned by dry etching. To prevent the plasma damage of active channel, a 100-nm-thckness $SiO_{x}$ by PECVD was adopted as an etch-stopper structure. IGZO TFT (W/L=10/50${\mu}m$) fabricated on glass exhibited the high performance mobility of $35.8\;cm^2/Vs$, a subthreshold gate voltage swing of $0.59V/dec$, and $I_{on/off}$ of $4.9{\times}10^6$. In addition, 4.1” transparent QCIF active-matrix organic light-emitting diode display were successfully fabricated, which was driven by a-IGZO TFTs.

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.28.1-28
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• 2001

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.465-470
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• 2007

The co-channel interference is a primary factor of loss in multimedia mobile communications. In this paper, we present a performance of the frequency reuse partitioning to refrain the co-channel interference and maximize system performance. First, we analyze the co-channel interference using the frequency reuse partitioning through the statistical modeling. From this results, we decide on the frequency reuse partitioning for the system throughput which is maximized. Finally, analysis and simulation results show that the frequency reuse partitioning based cellular system can mitigate the co-channel interference and maximize the system throughput. The experimental results show that system throughput is maximized from 0.7 to 0.8 according to traffic road. We can maximize the system throughput using the results with cellular system design parameter.

• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.818-823
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• 2015

In this study, FT reaction in a microchannel was simulated using computational fluid dynamics(CFD), and sensitivity analyses conducted to see effects of channel geometry variables, namely, process channel width, height, gap between process channel and cooling channel, and gap between process channels on the channel temperature profile. Microchannel reactor considered in the study is composed of five reaction channels with height and width ranging from 0.5 mm to 5.0 mm. Cooling surfaces is assumed to be in isothermal condition to account for the heat exchange between the surface and process channels. A gas mixture of $H_2$ and CO($H_2/CO$ molar ratio = 2) is used as a reactant and operating conditions are the following: GHSV(gas hourly space velocity) = $10000h^{-1}$, pressure = 20 bar, and temperature = 483 K. From the simulation study, it was confirmed that heat removal in an FT microchannel reactor is affected channel geometry variables. Of the channel geometry variables considered, channel height and width have significant effect on the channel temperature profile. However, gap between cooling surface and process channel, and gap between process channels have little effect. Maximum temperature in the reaction channel was found to be proportional to channel height, and not affected by the width over a particular channel width size. Therefore, microchannels with smaller channel height(about less than 2 mm) and bigger channel width (about more than 4 mm), can be attractive design for better heat removal and higher production.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.409-416
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• 2007

In cellular orthogonal frequency division multiplexing (OFDM) networks, co-channel interference (CCI) leads to severe degradation in the BER performance. To solve this problem, maximum-likelihood estimation (MLE) CCI cancellation scheme has been proposed in the literature. MLE CCI cancellation scheme generates weighted replicas of the transmitted signals where weights represent the estimated channel transfer functions. The replica with the smallest Euclidean distance from the received signal is selected and data are detected. When the received power of the desired and interference signals are nearly the same, the BER performance is degraded. In this paper, we propose a closed-loop power control (PC) scheme capable of detecting the equal received power situation at the mobile station (MS) receiver by using the newly introduced parameter power ratio (PR). When this situation is detected, the MS sends a feedback to the desired base station (BS) which boosts the transmission power in the next frame. At cell edge where signal to interferer ratio (SIR) is considered to have average value between -5 dB and 10 dB, computer simulations show that the proposed CCI cancellation scheme has a gain of 7 dB at 28 Km/h.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3412-3431
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• 2015

This paper considers the effect of co-channel interference on hybrid satellite-terrestrial relay network. In particular, we investigate the problem of amplify-and-forward (AF) relaying in hybrid satellite-terrestrial link, where the relay is interfered by multiple co-channel interferers. The direct link between satellite and terrestrial destination is not available due to masking by surroundings. The destination node can only receive signals from satellite with the assistance of a relay node situated at ground. The satellite-relay link is assumed to follow the shadowed Rice fading, while the channels of interferer-relay and relay-destination links experience Nakagami-m fading. For the considered AF relaying scheme, we first derive the analytical expression for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR). Then, we use the obtained MGF to derive the average symbol error rate (SER) of the considered scenario for M-ary phase shift keying (M-PSK) constellation under these generalized fading channels.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.45-45
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• 2003

We isolated a novel ankyrin-repeat containing protein, rSIAP (rSlo Interacting Ankyrin-repeat Protein), as an interacting protein to the cytosolic domain of the alpha-subunit of rat large-conductance Ca$\^$2+/-activated K$\^$+/ channel (rSlo) by yeast two-hybrid screening. Affinity pull-down assay showed the direct and specific interaction between rSIAP and rSlo domain. The channel-binding proteins can be classified into several categories according to their functional effects on the channel proteins, i.e. signaling adaptors, scaffolding net, molecular tuners, molecular chaperones, etc. To obtain initial clues on its functional roles, we investigated the cellular localization of rSIAP using immunofluorescent staining. The results showed the possible co-localization of rSlo and rSIAP protein near the plasma membrane, when co-expressed in CHO cells. We then investigated the functional effects of rSIAP on the rSlo channel using electrophysiological means. The co-expression of rSIAP accelerated the activation of rSlo channel. These effects were initiated at the micromolar [Ca$\^$2+/]$\_$i/ and gradually increased as [Ca$\^$2+/]$\_$i/ raised. Interestingly, rSIAP decreased the inactivation kinetics of rSlo channel at micromolar [Ca$\^$2+/]$\_$i/, while the rate was accelerated at sub-micromolar [Ca$\^$2+/]$\_$i/. These results suggest that rSIAP may modulate the activity of native BK$\_$Ca/ channel by altering its gating kinetics depending on [Ca$\^$2+/]$\_$i/. To localize critical regions involved in protein-protein interaction between rSlo and rSIAP, a series of sub-domain constructs were generated. We are currently investigating sub-domain interaction using both of yeast two-hybrid method and in vitro binding assay.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1079-1083
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• 2009

In this study, the distribution of $CO_2$ in an evaporator with 10 parallel micro channel aluminum tubes are experimentally investigated. Each tube has 6 circular micro channels with a diameter of 0.8mm. The tubes are heated with electric resistance wires, and the distribution of $CO_2$ into each tube is investigated by measuring the outer wall temperature. The outer wall temperature was found to be higher at the exit part of the top tube. It is thought that the $CO_2$ vapor at the upper part of the header reduces the mass flow rate of $CO_2$ into the top tube.