• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.191-194
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• 2003

In IEEE 802.11b, Medium Access Control Sublayer consists of DCF (Distributed Coordination Function) and PCF (Point Coordination Function). DCF provides contention based services and PCF provides contention free services for QoS satisfaction. DCF uses CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) as an access protocol. And PCF uses Polling Scheme. In this paper, a modified New-PCF, which gives weights to channels with heavier traffic load, was suggested. NS-2 simulations were conducted to compare the service performances with original DCF, PCF and the modified New-PCF respectively. Simulation results has shown the increased overall throughput with the proposed New-PCF compared with other cases.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.107-111
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• 2008

3GPP는 사용자의 다운링크 패킷 데이터 Throughput을 높이고,NodeB에 MAC계층을 위치시켜, 사용자의 스케줄링과 재전송을 담당하게 함으로써, 다운링크 패킷의 전송 지연을 감소시키는 HSDPA(High Speed Data Packet Access)기술을 Release 5에서 도입하였다. NodeB에 위치한 MAC-hs 스케줄러는 각각의 사용자에게 가용한 NodeB의 RF power와 code 자원을 제공하며, R99에서 사용했던 Power control을 이용하는 대신, AMC(Adaptive Modulation and Coding)기능을 제공하여 Radio conditions에 따라 전송되는 Data Format을 조정하여 채널환경이 좋은 사용자에게는 높은 data Throughput을 제공하며, 채널환경이 좋지 않은 사용자에게는 낮은 data throughput을 제공하고 있다. 본 고에서는 매 TTI에 스케줄링된 사용자에게 제공하고도, RF power 및 code 자원이 남아 있을 경우, 스케줄러는 남은 자원을 각각의 사용자에게 재 분배하여, 초기에 추정한 HSDPA Throughput보다 향상된 성능을 갖을 수 있음을 설명하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1685-1695
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• 2010

In this paper, we propose a new reliable multicast MAC protocol over the IEEE 802.11-based tactical ad hoc networks. The major contribution compared to the previous reliable multicast schemes using consecutive CTSs/ACKs is that the proposed scheme can send multiple CTS/ACK messages concurrently assisted by MC-DS/CDMA mechanisms. When multiple receivers receive the RTS/DATA message from a sender, they respond with the CTS/ACK message spread with pre-assigned code in the same time interval. The proposed scheme can reduce the overhead of multiple CTSs/ACKs. It is also possible to alleviate the received signal strength at the enemy detector and thus it improves low probability of detection performance. Through simulations and analysis, the proposed scheme outperforms that of the multiple CTSs/ACks in terms of the throughput, transmission delay and low probability of detection.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1458-1466
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• 2020

Oligomeric proanthocyanidins (OPCs), classified as condensed tannins, have significant antioxidation, anti-inflammation and anti-cancer effects. This study was performed to investigate the anti-inflammatory effects of OPCs and the mechanism underlying these effects in lipopolysaccharide (LPS)-stimulated bovine mammary epithelial cells (MAC-T). Real-time PCR and ELISA assays indicated that OPC treatment at 1, 3 and 5 ㎍/ml significantly reduced the mRNA and protein, respectively, of oxidant indicators cyclooxygenase-2 (COX-2) (p < 0.05) and inducible nitric oxide synthase (iNOS) (p < 0.01) as well as inflammation cytokines interleukin (IL)-6 (p < 0.01), IL-1β (p < 0.01) and tumor necrosis factor-α (TNF-α) (p < 0.05) in LPS-induced MAC-T cells. Moreover, OPCs downregulated LPS-induced phosphorylation of p65 and inhibitor of nuclear factor kappa B (NF-κB) (IκB) in the NF-κB signaling pathway (p < 0.01), and they inhibited p65 translocation from the cytoplasm to the nucleus as revealed by immunofluorescence test and western blot. Additionally, OPCs decreased phosphorylation of p38, extracellular signal regulated kinase and c-jun NH₂-terminal kinase in the MAPK signaling pathway (p < 0.01). In conclusion, the anti-inflammatory and antioxidant activities of OPCs involve NF-κB and MAPK signaling pathways, thus inhibiting expression of pro-inflammatory factors and oxidation indicators. These findings provide novel experimental evidence for the further practical application of OPCs in prevention and treatment of bovine mastitis.

• Nuclear industry
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• v.7 no.1 s.47
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• pp.88-93
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• 1987

• 한국전기화학회:학술대회논문집
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• 2003.04a
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• pp.12-12
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• 2003

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.630-638
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• 2001

This paper has been proposed a structure composed of FIRs and IIR filters as digital decimation filter to compensate the drooping inband on the high precision AU chips. The area of chip has been reduced compared with the conventional structure because the RAM and MAC is reduced. The passband ripple$(\leq\; 0.4535 \times fs)$, passband attenuation(at $\; 0.4535 \times fs$ and stopband attenuation$(\geq\; 0.59\times fs)$ of the 6th-order $\Delta\Sigma$ modulator and digital decimation filter had $\pm0.0007[dB]$, -0.0013[dB] and -110[dB] respectively. Also the inband group delay, which was almost same compared with the conventional digital decimation filter structure, was 30.07/fs[s] band the error of group delay was 0.1672%.

• Journal of Animal Science and Technology
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• v.64 no.5
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• pp.922-936
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• 2022

5-Hydroxytryptamine (5-HT), a monoamine, as a local regulator in the mammary gland is a chemical signal produced by the mammary epithelium cell. In cows, studies have shown that 5-HT is associated with epithelial cell apoptosis during the degenerative phase of the mammary gland. However, studies in other tissues have shown that 5-HT can effectively promote cell viability. Whether 5-HT could have an effect on mammary cell viability in dairy cows is still unknown. The purpose of this study was to determine: (1) effect of 5-HT on the viability of bovine mammary epithelial cells and its related signaling pathways, (2) interaction between prolactin (PRL) and 5-HT on the cell viability. The bovine mammary alveolar cell-T (MAC-T) were cultured with different concentrations of 5-HT for 12, 24, 48 or 72 hours, and then were assayed using cell counting kit-8, polymerase chain reaction (PCR) and immunobloting. The results suggested that 20 μM 5-HT treatment for 12 or 24 h promote cell viability, which was mainly induced by the activation of 5-HT receptor (5-HTR) 1B and 4, because the increase caused by 5-HT vanished when 5-HTR 1B and 4 was blocked by SB224289 and SB204070. And protein expression of mammalian target of rapamycin (mTOR), eukaryotic translation elongation factor 2 (eEF2), janus kinase 2 (JAK2) and signal transducer and activator of transcription 5 (STAT5) were decreased after blocking 5-HT 1B and 4 receptors. When MAC-T cells were treated with 5-HT and PRL simultaneously for 24 h, both the cell viability and the level of mTOR protein were significantly higher than that cultured with 5-HT or PRL alone. In conclusion, our study suggested that 5-HT promotes the viability of MAC-T cells by 5-HTR 1B and/or 4. Furthermore, there is a reciprocal relationship between PRL and 5-HT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.740-743
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• 2008

RSA crypto-processors equipped with more than 1024 bits of key space handle the entire key stream in units of blocks. The RSA processor which will be the target design in this paper defines the length of the basic word as 128 bits, and uses an 256-bits register as the accumulator. For efficient execution of 128-bit multiplication, $32b^*32b$ multiplier was designed and adopted and the results are stored in 8 separate 128-bit registers according to the stalks flag. In this paper, a fast 32bit nodular multiplier which is required to execute 128-bit MAC (multiplication and accumulation) operation is proposed. The proposed architecture prototype of the multiplier unit was automatically synthesized, and successfully operated at the frequency in the target RSA processor.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1B
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• pp.15-20
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• 2012

In this paper, an algorithm that enhances the conventional directional CSMA/CA protocol in IEEE 802.15.3c is proposed under saturation environments. For the algorithm, a Markov chain model is presented and analyzed in no-ACK mode. The effects of directional antennas and the features of IEEE 802.15.3c MAC are considered in the model. The optimal sizes of contention window are derived from the numerical results. The numerical results show that the proposed directional CSMA/CA algorithm outperforms conventional one. The overall analysis is verified by simulation. The obtained results provide the criterion for selecting the optimal parameters and developing a MAC protocol that enhances the performance of mmWave WPANs.