• Journal of Animal Science and Technology
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• v.52 no.6
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• pp.521-527
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• 2010

Fibroblast growth factor receptor 1 (FGFR1) plays roles in angiogenesis, wound healing, and embryonic development via the regulation of cell proliferation, differentiation, and survival. It is well known that ectopic expression of FGFR1 is associated with cancer development. To characterize the function of FGFR1 in the normal and cancer cell lines DF-1 and DT40, respectively, we performed FGFR1 knockdown by RNA interference. In the DT40 cells, FGFR1 knockdown induced upregulation of FGFR2 and FGFR3 expression, downregulation of pro-apoptosis-related genes, and upregulation of anti-apoptosis-related genes. However, in DF-1 cells, FGFR1 knockdown induced upregulation of pro-apoptosis-related genes and downregulation of anti-apoptosis-related genes. Our data suggest that repression of FGFR1 induced upregulation of other FGF receptors and anti-apoptosis-related genes in cancer cells and pro-apoptosis-related genes in normal cells.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.291-292
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• 2008

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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1077-1083
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• 2015

In this paper, we introduce an energy-efficient opportunistic interference alignment (OIA) scheme that greatly improves the sum-rates in multi-cell uplink networks. Each user employs optimal transmit vector design and power control in the sense of minimizing the amount of generated interference to other-cell base stations while satisfying a required signal quality. As our main result, it is shown that owing to the reduced interference level, the proposed OIA schemes attains larger sum-rates than those of OIA with no power control for almost all signal-to-noise ratio regions. In addition, when both zero-forcing and minimum mean square error (MMSE) detectors are employed at the receiver along with the OIA scheme, it is shown that the OIA scheme with MMSE detection shows superior performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.462-466
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• 1999

As the spectrum migrates to the higher frequency band around several milimeters wavelength for implementing wideband highspeed communications, it is more important to consider the channel attenuation characteristics of microwave signals. Microwave channels in 27GHz used in B-WLL system must be considered by compensating the power attenuation due to rainfall. So, in the design of one cell, the radiation power enhancement considering rainfall attenuation has an effort on the receiver in other cell as interference. In this paper we consider the main characteristics for B-WLL systems, optimum cell radius, and serviceable limit of heavy rainfall the design of the radiation power control system in case of enhancing the power that prevents from reducing the system capacity by interference.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.494-498
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• 2011

Satellite digital multimedia broadcasting (S-DMB) systems use gap fillers (GFs) to provide wireless multimedia services to non-line-of-sight locations. GFs act as repeaters, and S-DMB systems require GF networks in order to guarantee mobile reception. Each GF covers a cell or sector. In order to provide contiguous coverage of an area comprising two or more cells or sectors, multiple GFs are needed. However, when multiple GFs are situated close to each other, interference is likely to occur. As a result, in this study, we have investigated system-level environments for planning the design of interference-free GF networks in S-DMB systems. Our investigations revealed that S-DMB services are unavailable because of quality deterioration caused by interference when the delay attributable to a GF and the satellite signals exceeds ${\pm}$256 chips and the distance between the GF and its reception terminal is greater than 4.6 km. On the basis of this analysis, we conducted a field test that confirmed that the above-mentioned time delay can be controlled in such a way as to ensure high quality S-DMB services.

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.19-27
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• 2010

In recent years, high-throughput genome-wide RNA interference screening is emerging as an essential tool to biologists in understanding complex cellular processes. The manual analysis of the large number of images produced in each study spends much time and the labor. Hence, automatic cellular image analysis becomes an urgent need, where segmentation is the first and one of the most important steps. However, those factors such as the region overlapping, a variety of shapes, and non-uniform local characteristics of cellular images become obstacles to efficient cell segmentation. To avoid the problem, a new watershed-based cell segmentation algorithm using a localized segmentation method and a feature vector is proposed in this paper. Localized approach in segmentation resolves the problems caused by a variety of shapes and non-uniform characteristics. In addition, the poor performance of segmentation in overlapped regions can be improved by taking advantage of a feature vector whose component features complement each other. Simulation results show that the proposed method improves the segmentation performance compared to the method in Cellprofiler.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9A
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• pp.784-789
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• 2011

In this paper, a precoder based on limited phase feedback is proposed to maximize user's receive signal-to-interference-plus-noise ratio (SINR) in coordinated multi-point (CoMP) coordinated scheduling / coordinated beamforming (CS/CB) precoding matrix indicator (PMI) scenario. Most conventional precoding techniques based on limited phase feedback have been considered in a single-cell environment. However, considering neighboring cells in a multi-cell environment, we enhance the conventional preocoding. method. First, to maximize receive SINR, precoding matrices are designed to maximize the serving cell's signal and to minimize the coordinated cells' signal. Also, a precoder which can be used in a limited bit feedback condition is suggested. Finally, the proposed precoder's performance is evaluated and compared with some other precoding techniques by using simulation under the CoMP CS/CB PMI scenario.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4703-4723
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• 2018

In recent years, dense small cell network has been deployed to address the challenge that has resulted from the unprecendented growth of mobile data traffic and users. It has proven to be a cost efficeient solution to offload traffic from macro-cells. Software defined heterogeneous wireless network can decouple the control plane from the data plane. The control signal goes through the macro-cell while the data traffic can be offloaded by small cells. In this paper, we propose a framework for cell virtualization and user association in order to satisfy versatile requirements of multiple tenants. In the proposed framework, we propose an interference graph partioning based virtual-cell association and customized physical-cell association for multi-homed users in a software defined small cell network. The proposed user association scheme includes 3 steps: initialization, virtual-cell association and physical-cell association. Simulation results show that the proposed virtual-cell association outperforms the other schemes. For physical-cell association, the results on resource utilization and user fairness are examined for mobile users and infrastructure providers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5A
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• pp.276-283
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• 2003

Most of CDMA system algorithm must be verified by simulating the cellular system consisted of many other tier cells. But it takes long time to simulate such a huge CDMA cellular system. In this paper, we propose an effective time saving simulation scheme based on wraparound technique. And we study that how our remaining cell interference compensation method works on calculating of the total interference, SIR, outage probability, and cell capacity. We made a conclusion that by using proposed scheme, we can get the same result of maximum configuration cells with only one tier real cells and that we can minimize the simulation time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11A
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• pp.822-830
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• 2009

The spectrum efficiency of mobile communication networks can be improved dramatically adopting multiple antennas technologies. In order to guarantee the licensed rights of primary user (PU), the cognitive radio system should perform in a relatively low interference manner when it gets access to the spectrum of licensed networks. In this paper, we explore a uniformly distributed circular antenna array to implement beamforming algorithm that is accomplished by optimization method at the base station of cognitive radio networks, and therefore we can suppress the interference to PU by steering quite low transmission power toward PU and constructing a narrow beam toward cognitive user (CU). By reducing the constraint number of the optimization problem, we also propose a null steering algorithm that steers rather low radiation power toward PU, while the other areas in the same cell are covered by radiation power except the local area around PU. It is pursued to reduce the computation load and enlarge the capacity of cognitive radio networks extremely. The simulation results demonstrate that the proposed algorithms process superior performance.