모바일 와이맥스 시스템에서 인접 셀 간섭 완화를 위한 채널 추정

In orthogonal frequency division multiplexing based wireless system, a pilot signal is often employed to estimate channel state information (CSI). However, the received pilot signal is interfered by other cell interference in multi-cell environments. We consider the estimation of CSI by utilizing orthogonal preambles and channel correlation.Seoul R&BD Progra

Preamble-Assisted Channel Estimation in OFDM-based Wireless Systems

Accurate channel state information (CSI) is indispensable for the use of channel-adaptive transmission techniques, but it may not easily be achievable near the cell boundary in cellular environments. This paper considers the improvement of CSI estimation accuracy in OFDM-based wireless packet transmission systems by exploiting the preamble signal as well as the pilot signal. The CSIs respectively estimated from the received preamble and pilot signal are combined according to the channel correlation between the preamble and the pilot signaling. The combining weight is analytically determined to minimize the mean squared error. When multiple antennas are employed for interference cancellation, the CSI of interference channels can also be estimated in a similar manner. The proposed scheme is applied to the mobile-WiMAX system to verify the effectiveness. Simulation results show that the proposed scheme is quite effective near the cell boundary.This work was in part supported by the IT R&D program of MKE/IITA (2008-F-007-01, Intelligent Wireless Communication Systems in 3 Dimensional Environment)

Adaptive Grouping MMSE Channel Estimation in OFDM-Based Wireless Systems

In this paper, we design an minimum meansquare error (MMSE)-type channel estimation scheme in orthogonal frequency division multiplexing-based wireless systems. By using the averaged channel frequency response (CFR) of pilot symbols in a group as a representative CFR , the proposed MMSE channel estimator can reduce the mean-square error (MSE) of channel estimation by achieving the signal-to-noise ratio (SNR) gain without increasing the computational complexity compared to conventional MMSE channel estimator. The grouping size of pilot symbols is optimized to minimize the MSE according to the channel correlation characteristics. Finally, the performance of the proposed channel estimation scheme is verified by computer simulation.This work was in part supported by the IT R&D program of MKE/IITA (2008-F-007-01, Intelligent Wireless Communication Systems in 3 Dimensional Environment)

o-Carboranylalkoxy-1,3,5-Triazine Derivatives: Synthesis, Characterization, X-ray Structural Studies, and Biological Activity

Morpholine- and bis(2-methoxyethyl)amine-substituted 1,3,5-triazine derivatives containing an alkoxy-o-carborane in the 6-position of the triazine ring were successfully synthesized. The molecular structures of the methoxy- and ethoxy-o-carboranyl-1,3,5-triazines were established by X-ray crystallography. In vitro studies showed that the methylene bridged morpholine- and bis(2-methoxyethyl)amine-substituted o-carboranyl-1,3,5-triazines accumulated to high levels in B16 melanoma cells and exhibited higher cytotoxicity than p-boronophenylalanine

Design and Implementation for the Electronic Parking Brake System Based on Operating System

Electronic Parking Brake(EPB) system is operated by Electronic Control unit(ECU). EPB system has been by replaced a traditional parking brake system, which is a mechanical device to be driven by a parking brake lever or foot pedal. EPB system is more convenient for the women and elderly. Interior design as well as space utilization has also been important recently. By using EPB system, it is possible to ensure more space in a vehicle. Also, EPB system provides better convenience and safety than the traditional system through the cooperative control of Electric Stability Program(ESP) or alone. In this paper, we propose methodology of software architecture design and function development for the EPB system based on software tools.1

UPLC-MS/MS-Based Profiling of Eicosanoids in RAW264.7 Cells Treated with Lipopolysaccharide

While both the pro- and anti-inflammatory effects of several eicosanoids have been widely studied, the degree of inflammation in cells that results from various eicosanoids has yet to be comprehensively studied. The objective of this study was to assess the effect of lipopolysaccharide (LPS) treatment on eicosanoid content in RAW264.7 cells. An Ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS)-based profiling method was used to analyze the eicosanoid contents of RAW264.7 cells treated with different LPS concentrations. The profiling data were subjected to statistical analyses, such as principal component analysis (PCA) and hierarchical clustering analysis. LPS treatment increased nitric oxide production and secretion of pro-inflammatory cytokines, such as tumor necrosis factor-α and interleukin-6, in a concentration-dependent manner. In total, 79 eicosanoids were identified in the cells. RAW264.7 cells treated with different LPS concentrations were well differentiated in the PCA score plot. A heatmap was used to identify the eicosanoids that were up- or down-regulated according to the degree of inflammation and LPS concentration. Thirty-nine eicosanoids were upregulated and seven were down-regulated by LPS treatment in a concentration-dependent manner. Our novel UPLC-MS/MS technique can profile eicosanoids, and can evaluate the correlations between inflammation and eicosanoid metabolism

Cancer-specific cytotoxicity of pyridinium-based ionic liquids by regulating hypoxia-inducible factor-1α-centric cancer metabolism

Owing to their unique properties and biological activities, ionic liquids (ILs) have attracted research interest in pharmaceutics and medicine. Hypoxia-inducible factor (HIF)− 1α is an attractive cancer drug target involved in cancer malignancy in the hypoxic tumor microenvironment. Herein, we report the inhibitory activity of ILs on the HIF-1α pathway and their mechanism of action. Substitution of a dimethylamino group on pyridinium reduced hypoxia-induced HIF-1α activation. It selectively inhibited the viability of the human colon cancer cell line HCT116, compared to that of the normal fibroblast cell line WI-38. These activities were enhanced by increasing the alkyl chain length in the pyridinium. Under hypoxic conditions, dimethylaminopyridinium reduced the accumulation of HIF-1α and its target genes without affecting the HIF1A mRNA level in cancer cells. It suppressed the oxygen consumption rate and ATP production by directly inhibiting electron transfer chain complex I, which led to enhanced intracellular oxygen content and oxygen-dependent degradation of HIF-1α under hypoxia. These results indicate that dimethylaminopyridinium suppresses the mitochondria and HIF-1α-dependent glucose metabolic pathway in hypoxic cancer cells. This study provides insights into the anticancer activity of pyridinium-based ILs through the regulation of cancer metabolism, making them promising candidates for cancer treatment