Ji-Woong Choi

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When a preamble signal is repeated multiple times in OFDM systems, we derive joint maximum likelihood (ML) estimation of the frame timing (FT) and carrier frequency offset (CFO). Unlike conventional estimators which use correlation of adjacent repetition patterns only or some specific sets of patterns, the joint ML estimation exploits correlation of any(More)
Noncoding small regulatory RNA molecules control gene expression and microRNAs provide one of the best examples in eukaryotes. However, bacterial RNAs of comparable size to eukaryotic microRNAs have received little attention. Here, we demonstrate the existence of microRNA-size, small RNAs (msRNAs) in the model bacterium Escherichia coli. We examined the(More)
To maintain the Internet connectivity of a group of nodes in intelligent transportation systems (ITSs), the network mobility basic support (NEMO BS) protocol was standardized. The NEMO BS provides mobility for mobile network nodes (MNNs) in a moving network through a mobile router (MR). Since packet loss in NEMO dramatically increases during a handover as(More)
The network mobility basic support (NEMO BS) protocol has been investigated to provide Internet connectivity for a group of nodes, which is suitable for intelligent transportation systems (ITS) applications. NEMO BS often increases the traffic load and handover latency because it is designed on the basis of mobile Internet protocol version 6 (MIPv6).(More)
In the present study, we investigated the possible mechanisms of cellular injury induced by zinc in rat primary astrocytes and C6 glioma cells. Reactive oxygen species (ROS) production, cellular glutathione (GSH) level and mitochondrial transmembrane potential were examined. Exposure to 200–300 μM Zn2+ for 24 h resulted in significant lactate dehydrogenase(More)
Little is known about the detail of hypoxia-responsive gene expression patterns in advanced age, even though aging is thought to be partially associated with a decreased response to hypoxia. In the present study, we identified several hypoxia-inducible genes and investigated the effect of aging on hypoxic gene expression profiles using cDNA microarray(More)
Oxytocin (Oxt), produced in the hypothalamic paraventricular and supraoptic nuclei for transport to and release from the posterior pituitary, was originally discovered through its role in lactation and parturition. Oxt also plays important roles in the central nervous system by influencing various behaviors. MicroRNAs (miRNAs), endogenous regulators of many(More)
Mutation in the von Hippel-Lindau (VHL) protein associated with renal cell carcinoma causes hypoxia-inducible factor (HIF) to stabilize and consequently to induce various HIF-targeting proteins. In this study, we found that proopiomelanocortin (POMC), an adrenocorticotropic hormone precursor, is up-regulated constitutively in VHL-mutated renal cell(More)
The efficient service of a tremendous number of machine-type devices with heterogeneous traffic types may consider simple random access as a solution. For more rigorous analysis of system performance in multicell environments, it is required to consider not only the packet collisions within the same cell but also the interference from other cells. This(More)
The performance of a MIMO-OFDM system significantly depends upon the accuracy of the channel impulse response (CIR) estimates. In the presence of correlation between the CIRs of the transmit or receive antennas, it is desirable to exploit this correlation to improve the performance of CIR estimation. In this letter, we propose a low-complexity channel(More)