• Journal of Broadcast Engineering
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• v.11 no.3 s.32
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• pp.302-310
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• 2006

ITU-R B.O. 1130-4 Digital System E adopted for Korean satellite DMB service is a multimedia broadcasting system based on DS-CDM-QPSK technique which broadcasts audio and video contents via the satellite or terrestrial gap-filler. However, Digital System E can not provide full loading services because the multi-channel interference (MCI) is increased due to the loss of orthogonality between signature waveforms in multipath fading channels. In this paper a chip equalizer using tap selection algorithm that enhances the receiving performance is proposed and compared to the conventional rake receiver for the satellite DMB system.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.1
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• pp.25-33
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• 2016

Ion channels in carcinoma and their roles in cell proliferation are drawing attention. Intracellular $Ca^{2+}$ ($[Ca^{2+}]_i$)-dependent signaling affects the fate of cancer cells. Here we investigate the role of $Ca^{2+}$-activated $K^+$ channel (SK4) in head and neck squamous cell carcinoma cells (HNSCCs) of dif-ferent cell lines; SNU-1076, OSC-19 and HN5. Treatment with $1{\mu}M$ ionomycin induced cell death in all the three cell lines. Whole-cell patch clamp study suggested common expressions of $Ca^{2+}$-activated $Cl^-$ channels (Ano-1) and $Ca^{2+}$-activated nonselective cation channels (CAN). 1-EBIO, an activator of SK4, induced outward $K^+$ current (ISK4) in SNU-1076 and OSC-19. In HN5, ISK4 was not observed or negligible. The 1-EBIO-induced current was abolished by TRAM-34, a selective SK4 blocker. Interestingly, the ionomycin-induced cell death was effectively prevented by 1-EBIO in SNU-1076 and OSC-19, and the rescue effect was annihilated by combined TRAM-34. Con-sistent with the lower level of ISK4, the rescue by 1-EBIO was least effective in HN5. The results newly demonstrate the role of SK4 in the fate of HNSCCs under the $Ca^{2+}$ overloaded condition. Pharmacological modulation of SK4 might provide an intriguing novel tool for the anti-cancer strategy in HNSCC.

• The Korean Journal of Physiology and Pharmacology
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• v.10 no.2
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• pp.95-99
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• 2006

Employing electrophysiological and cell proliferation assay techniques, we studied the effects of $Ca^{2+}$ -activated $K^+$ channel modulators on the proliferation of human dermal fibroblasts, which is important in wound healing. Macroscopic voltage-dependent outward $K^+$ currents were found at about -40 mV stepped from a holding potential of -70 mV. The amplitude of $K^+$ current was increased by NS1619, a specific large-conductance $Ca^{2+}$-activated $K^+$ (BK) channel activator, but decreased by iberiotoxin (IBTX), a specific BK channel inhibitor. To investigate the presence of an intermediate-conductance $Ca^{2+}$-activated $K^+$ (IK) channels, we pretreated the fibroblasts with low dose of TEA to block BK currents, and added 1-EBIO (an IK activator). 1-EBIO recovered the currents inhibited by TEA. When various $Ca^{2+}$-activated $K^+$ channel modulators were added into culture media for 1∼3 days, NS1619 or 1-EBIO inhibited the cell proliferation. On the other hand, IBTX, clotrimazole or apamin, a small conductance $Ca^{2+}$-activated $K^+$ channel (SK) inhibitor, increased it. These results suggest that BK, IK, and SK channels might be involved in the proliferation of human dermal fibroblasts, which is inversely related to the channel activation.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.343-344
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• 2007

In this paper, we study the signed-DLMS adaptive algorithm of wireless repeater for solving shadow region due to propagation between base station and mobile station. The the signed-DLMS algorithm reduces interference signals from multipath and solves the oscillation problem of repeater by estimation and cancellation. To efficiently reject interference signal, the signed-DLMS adaptive algorithm is applied. The computational complexities of the signed-DLMS are reduced verse standard LMS algorithm. Wireless ICS repeater based on signed-DLMS reduces the cost and is able to increase channel capacities.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.56-58
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• 2014

본 논문에서는 압축 도메인에서 고속으로 움직임을 검출하고 해당 구간을 저장 하는 알고리즘을 제안한다. 제안하는 알고리즘은 H.264/AVC 기반의 압축 비트스트림에서 움직임 벡터와 참조프레임을 이용하여 움직임이 있는 프레임을 검출하고 움직임 유무에 따라 GOP 단위로 저장하는 과정을 수행한다. 압축도메인에서 움직임 검출과 구간 저장을 수행함으로써 복잡도를 낮추고 비디오 저장을 위한 공간을 절약해 실시간 다채널 영상 처리에 최적화 된 성능을 제공한다. 제안하는 움직임 검출 및 저장 시스템은 single thread 환경에서 실시간으로 평균 2957 프레임을 처리 가능하며, Multi thread의 경우 30 fps 영상 98개 채널을 실시간으로 처리 가능하다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.77-78
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• 2008

With advent of 3G mobile communication services, video telephony becomes one of the major services. However, due to a narrow channel bandwidth, the current video telephony services have not yet reached a satisfied level. In this paper, we propose an ROI (Region-Of-Interest) based improvement of visual quality for video telephony services with the H.264|MPEG-4 Part 10 (AVC: Advanced Video Coding) codec. To this end, we propose a face detection and tracking method to define ROI for the AVC codec based video telephony. Experiment results show that our proposed ROI based method allowed for improved visual quality in both objective and subjective perspectives.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.41-41
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• 2003

Small conductance calcium-activated potassium channels (or SKCa channels) are potassium selective, voltage-independent, and activated by intracellular calcium concentration. These channels play important roles in excitable cells such as neuron in the central nervous system (Vergara et al., 1998). The activity of SKCa channels underlies the slow afterhyperpolarization that inhibits neuronal cell firing (Hille, 1991; Vergara et al.,1998). Until now, N-terminal region of rSK2 isn't characterized. To study the role of N-terminus, we constructed the N-terminal deletion mutant and characterized by electrophysiological means. Interestingly, N-terminal deletion mutant be trafficked to membrane couldn't evoke any ionic currents. Thus, N-terminal region has a role in functional rSK2 channel formation. To elucidate the function of N-terminal region, (His)6-conjugated protein was purified and filtrated by affinity column chromatography. Surprisingly, N-terminal region was shown in tetramer size that was supported by cross-linking result. Thus, we predicted that N-terminal region might be involved in the tetramerization of rSK2.

• Information Systems Review
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• v.25 no.3
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• pp.121-138
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• 2023

The advancement in mobile technology brought disruptive innovation in media industry. The introduction of mobile devices broke spatial and temporal restrictions in media consumption. This study investigates the impact of mobile channel adoption on video viewing behavior, using real-world dataset obtained from a particular on-demand service provider in South Korea. We find that the adoption of a mobile channel significantly increases the total viewing time of video-on-demand via TV and the number of contents viewed. Our results suggest that the mobile channels act as a complement channel to conventional TV channels. We provide theoretical and practical insights on consumer usage in the emerging over-the-top market.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.181-184
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• 2000

In this paper, performance of an optical CDMA system with PCCC and SCCC is simulated and compared. It is assumed that optical channel is an intensity modulated (IM) channel and direct-detection scheme is employed to detect the received optical signal. The modulation scheme used is pulse-position-modulation (PPM). The performance is evaluated in terms of bit error probability. From the simulation results, it is shown that turbo coding offers considerable coding gain with reasonable encoding/decoding complexity.

• BMB Reports
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• v.44 no.10
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• pp.635-646
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• 2011

Due to its high external and low internal concentration the $Ca^{2+}$ ion is used ubiquitously as an intracellular signaling molecule, and a great many $Ca^{2+}$-sensing proteins have evolved to receive and propagate $Ca^{2+}$ signals. Among them are ion channel proteins, whose $Ca^{2+}$ sensitivity allows internal $Ca^{2+}$ to influence the electrical activity of cell membranes and to feedback-inhibit further $Ca^{2+}$ entry into the cytoplasm. In this review I will describe what is understood about the $Ca^{2+}$ sensing mechanisms of the three best studied classes of $Ca^{2+}$-sensitive ion channels: Large-conductance $Ca^{2+}$-activated $K^+$ channels, small-conductance $Ca^{2+}$-activated $K^+$ channels, and voltage-gated $Ca^{2+}$ channels. Great strides in mechanistic understanding have be made for each of these channel types in just the past few years.