• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.18 no.4
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• pp.317-335
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• 2014

In this work, we investigate the global stability analysis of a viral infection model with antibody immune response. The incidence rate is given by a general function of the populations of the uninfected target cells, infected cells and free viruses. The model has been incorporated with two types of intracellular distributed time delays to describe the time required for viral contacting an uninfected cell and releasing new infectious viruses. We have established a set of conditions on the general incidence rate function and determined two threshold parameters $R_0$ (the basic infection reproduction number) and $R_1$ (the antibody immune response activation number) which are sufficient to determine the global dynamics of the model. The global asymptotic stability of the equilibria of the model has been proven by using Lyapunov theory and applying LaSalle's invariance principle.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.714-716
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• 2005

We studied the dependence of the electrical characteristics of MgO protecting layer on temperature in an AC PDP cell. Careful measurements of the surface resistance of MgO were performed for the temperature range from room temperature to $100^{\circ}C$ with and without the VUV illumination. Experimental results show that the resistivity is affected by not only the temperature but also VUV irradiation. The measurement of wall charge distribution and the address discharge delay time as to the temperature show that the resistivity change of MgO may affect the wall voltage and consequently the discharge delay time.

• ETRI Journal
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• v.38 no.1
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• pp.81-89
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• 2016

In this paper, a beam ID preamble (BIDP) technique, where a beam ID is transmitted in the physical layer, is proposed for efficient beam training in millimeter-wave cellular communication systems. To facilitate beam ID detection in a multicell environment with multiple beams, a BIDP is designed such that a beam ID is mapped onto a Zadoff-Chu sequence in association with its cell ID. By analyzing the correlation property of the BIDP, it is shown that multiple beams can be transmitted simultaneously with the proposed technique with minimal interbeam interference in a multicell environment, where beams have different time delays due to propagation delay or multipath channel delay. Through simulation with a spatial channel model, it is shown that the best beam pairs can be found with a significantly reduced processing time of beam training in the proposed technique.

• Journal of Multimedia Information System
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• v.5 no.2
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• pp.139-142
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• 2018

This work presents a novel architecture of phase locked loop (PLL) with the current compensating scheme to improve phase noise characteristic. The proposed PLL has two charge pumps (CP), main-CP (MCP) and sub-CP (SCP). The smaller SCP current with same time duration but opposite direction of UP/DN MCP current is injected to the loop filter (LF). It suppresses the voltage fluctuation of LF. The PLL has a novel voltage controlled oscillator (VCO) consisting of a voltage controlled resistor (VCR) and the three-stage ring oscillator with latch type delay cells. The VCR linearly converts voltage into current, and the latch type delay cell has short active on-time of transistors. As a result, it improves phase noise characteristic. The proposed PLL has been fabricated with $0.35{\mu}m$ 3.3 V CMOS process. Measured phase noise at 1 MHz offset is -103 dBc/Hz resulting in 3 dBc/Hz phase noise improvement compared to the conventional PLL.

• Molecules and Cells
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• v.20 no.1
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• pp.136-141
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• 2005

Mild stresses such as high temperature ($30^{\circ}C$) or a low $H_2O_2$ concentration induced transient cell cycle arrest at G1/S or G2/M depending on the cell cycle stage at which the stress was applied. When stresses were introduced during G0 or G1, the G1/S checkpoint was mainly used; when stresses were introduced after S phase, G2/M was the primary checkpoint. The slowing of cell cycle progression was associated with transient delays in expression of A-, B-, and D-type cyclins. The delay in expression of NtcycA13, one of the A-type cyclins, was most pronounced. The levels of expression of Ntcyc29 (a cyclin B gene) and of CycD3-1 differed most depending on the applied stress, suggesting that different cellular adjustments to mild heat and a low concentration of $H_2O_2$ are reflected in the expression of these two cyclins.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2009-2014
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• 2007

Hydrogen is a fuel of fuel cell system, which has powerful explosion possibility. Hence, the fuel cell system needs safety evaluation to prevent risk of hydrogen leakage. We use a actual size chamber of a common fuel cell module to analyze hydrogen. Hydrogen injection holes are located in lower part of the chamber in order to simulated hydrogen leakage. The hydrogen sensor can detect range of 0${\sim}$4%. Since the hydrogen gas, of which leaked amount is controled by MFC, are injected at the bottom holes, the transient sensor signals are measured. At a condition of 10cc/s of hydrogen leakage, the sensor detects hydrogen leakage after 22sec and there is also several seconds of time delay depending on the position of the sensor. This experimental data can be applied for the design of the hydrogen detection system and ventilation system of a residential fuel cell system.

• Toxicological Research
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• v.17
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• pp.59-69
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• 2001

Arsenic exposure is associated with several human diseases, including cancers, atherosclerosis, hypertension, and cerebrovascular diseases. In cultured cells, arsenite, an inorganic arsenic com-pound, was demonstrated to interfere with many physiological functions, such as enhancement of oxidative stress, delay of cell cycle progression, and induction of structural and numerical changes of chromosomes. The objective of this study is to investigate the effects of arsenic exposure on gene expression profiles by colorimetric cDNA microarray technique. HFW (normal human diploid skin fibroblasts), CL3 (human lung adenocarcinoma cell line), and HaCaT (immortalized human keratinocyte cell line) were treated with 5 $\mu\textrm{M}$ or 10 $\mu\textrm{M}$ sodium arsenite for 6 or 16 h, respectively. By a dual-color detection system, the expression profile of arsenite-treated cultures was compared to that of control cultures. Several genes expressed differentially were identified on the microarray membranes. For example, MDM2, SWI/SNF, ubiquitin specific protease 4, MAP3K11, RecQ protein-like 5, and Ribosomal protein Ll0a were consistently induced in all three cell types by arsenite, whereas prohibitin, cyclin D1, nucleolar protein 1, PCNA, Nm23, and immediate early protein (ETR101) were apparently inhibited. The present results suggest that arsenite insults altered the expression of several genes participating in cellular responses to DNA damage, stress, transcription, and cell cycle arrest.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.2
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• pp.354-363
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• 1994

This paper describes the method that voice traffic is served efficiently in BISDN. Voice is divided into talkspurt and silent period, and it is possible to transmit olny talksurt by the speech activity detection. This paper described the voice traffic control algorithm in the ATM network where cell discarding method is applied to the embedded ADPCM voice data. For traffic control, the cell discarding was used over low priority cells when it overflows the queue threshold. To estimate the efficiency of traffic control algorithm, the computer simuation was performed with cell loss probability, queue length and mean delay as performance parameters. The embedded ADPCM voice coding and cell disscarding resulted in improving the voice cell traffic efficiency and the dynamic control over network congestion.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2328-2339
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• 1994

The PBS(Partial Buffer Sharing) space priority mechanism is one of priority control methods which may improve the performance of a single server queueing system when mixed traffic with different performance requirements is applied to the system. This paper analyzes the cell loss behavior of PBS assuming loss sensitive traffic and delay sensitive traffic are applied to the system. To derive the successive cell loss probabilities. which are an important performance measure of realtime traffic, we develop a recursive algorithm. Performance results show the successive cell loss probabilities obtained by our method are lager than the probabilities derived from an independent cell loss assumption. These results may indicate the limitation of PBS for realtime traffic and the increase of the admissible load with the criterion of quality of service.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.635-656
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• 2019

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.