• Journal of the Korea Society for Simulation
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• v.17 no.3
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• pp.1-8
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• 2008

It is essential to maintain constant QoS despite of cell overload or erroneous wireless link during transmission because QoS of a multimedia service may be severely degraded by small delay or packet loss. This paper deals with a cell selection method for supporting the QoS of multimedia services over heterogeneous networks. The proposed scheme is based on Fuzzy Multi-Criteria Decision Making (FMCDM), in which uncertain parameters such as user system preference, the communication cost and cell load, and the transmission delay are used in the decision process using the aggregation function in fuzzy set theory. In this scheme, errors in the evaluation parameters impose milder changes on the total evaluation value than in binary logics. Simulation is focused on the average delay and packet loss rate, and the simulation results show that our proposed method provides mobile terminals the optimal performance.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.267-274
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• 2015

Due to the difficulty of coordination in the cellular uplink, it is a practical challenge how to achieve the optimal throughput scaling with distributed scheduling. In this paper, we propose a distributed and opportunistic user scheduling (DOUS) that achieves the optimal throughput scaling in a single-input multiple-output interfering multiple-access channel, i.e., a multi-cell uplink network, with M antennas at each base station (BS) and N users in a cell. In a distributed fashion, each BS adopts M random receive beamforming vectors and then selects M users such that both sufficiently large desired signal power and sufficiently small generating interference are guaranteed. As a main result, it is proved that full multiuser diversity gain can be achieved in each cell when a sufficiently large number of users exist. Numerical evaluation confirms that in a practical setting of the multi-cell network, the proposed DOUS outperforms the existing distributed user scheduling algorithms in terms of sum-rate.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.5
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• pp.275-284
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• 2014

This paper considers two-tier networks consisting of macrocells and femtocells operating in the same spectrum. This paper proposes a femtocell spectrum reuse scheme that determines the shared spectrum and transmit power for the femtocells to mitigate the effects of cross-tier interference between the macrocells and femtocells. The proposed scheme provides macrocell throughput that is unaffected by the increasing number of femtocells per cell site and improves the femtocell signal quality at the same time by limiting the cross-tier interference. This study analyzed the per-tier signal-to-interference ratio (SIR) and outage probability of the proposed scheme to investigate the macrocell and femtocell performance. The total throughput of the proposed scheme was analyzed based on the outage probabilities. The analysis and numerical results proved that high femtocell throughput can be achieved using only a small fraction of the spectrum while protecting the macrocell throughput. As a result, an improved total throughput was achieved enforcing higher spatial reuse.

• ETRI Journal
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• v.35 no.5
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• pp.775-785
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• 2013

Because of their exclusive features, millimeter wave directive mesh networks can be considered for small cell backhaul support in urban environments. For this purpose, a network of closely spaced stations has been considered with very directive line-of-sight links operating in the 60-GHz band. An attempt is made to evaluate channel response and interference behavior in such a network, taking into account the effect of building blockage. A simple grid of building blocks is considered as the propagation environment, and wave propagation is simulated using 2.5-dimensional (2.5D) ray tracing (2D with ground effect) to calculate the received signal at different nodes in the network. The results are compared with free space predictions and used to evaluate interference at all nodes in the channel and describe certain characteristics of links, such as the delay profile and the correlation length.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2563-2568
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• 2013

Recently, various solutions to support explosively growing mobile data traffic have attracted intensive attentions. However, the range of spectrum which can be exploited for mobile communications is very limited. Small cell networks are actively investigated because they can efficiently offload mobile data traffic from macro cells without using additional spectrum. In this paper, we developed a system-level simulator considering small cell networks in the indoor environments. We compare the performance of outage probability when a load-balancing algorithm is utilized or not. We can reduce the outage probability of congested BS with the load-balancing algorithm. In addition, overall outage probability of whole wireless systems can be reduced by using the proposed load-balancing algorithm.

• Journal of the Korea Computer Graphics Society
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• v.28 no.1
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• pp.1-9
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• 2022

Non-small cell lung cancer (NSCLC) accounts for a high proportion of 85% among all lung cancer and has a significantly higher mortality rate (22.7%) compared to other cancers. Therefore, it is very important to predict the prognosis after surgery in patients with non-small cell lung cancer. In this study, the types of preoperative chest CT image patches for non-small cell lung cancer patients with tumor as a region of interest are diversified into five types according to tumor-related information, and performance of single classifier model, ensemble classifier model with soft-voting method, and ensemble classifier model using 3 input channels for combination of three different patches using pre-trained ResNet and EfficientNet CNN networks are analyzed through misclassification cases and Grad-CAM visualization. As a result of the experiment, the ResNet152 single model and the EfficientNet-b7 single model trained on the peritumoral patch showed accuracy of 87.93% and 81.03%, respectively. In addition, ResNet152 ensemble model using the image, peritumoral, and shape-focused intratumoral patches which were placed in each input channels showed stable performance with an accuracy of 87.93%. Also, EfficientNet-b7 ensemble classifier model with soft-voting method using the image and peritumoral patches showed accuracy of 84.48%.

• Bulletin of the Korean Chemical Society
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• v.35 no.5
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• pp.1294-1298
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• 2014

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer representing 85% of lung cancer patients. Despite several EGFR-targeted drugs have been developed in the treatment of NSCLC, the clinical efficacy of these EGFR-targeted therapies is being challenged by the occurrence of drug resistance. In this regard, Hsp90 represents great promise as a therapeutic target of cancerous diseases due to its role in modulating and stabilizing numerous oncogenic proteins. Accordingly, inhibition of single Hsp90 protein simultaneously disables multiple signaling networks so as to overcome drug resistance in cancer. In this study, we synthesized a series of 11 butein analogues and evaluated their biological activities against gefitinibresistant NSCLC cells (H1975). Our study indicated that analogue 1h inhibited the proliferation of H1975 cells, down-regulated the expression of Hsp90 client proteins, including EGFR, Met, Her2, Akt and Cdk4, and upregulated the expression of Hsp70. The result suggested that compound 1h disrupted Hsp90 chaperoning function and could serve a potential lead compound to overcome the drug resistance in cancer chemotherapy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.583-585
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• 2016

The recent advances in wireless networks area have led to new techniques, such as small cells or full-duplex (FD) transmission, have also been developed to further increase the network capacity. Particularly, full-duplex communication promises expected throughput gain by doubling the spectrum compared to half-duplex (HD) communication. Because this technique permits one set of frequencies to simultaneously transmit and receive signals. In this paper, we focus on the binary power control for the users and the base stations in full-duplex multiple cellulars wireless networks to obtain optimal sum-rate under the effect interference and noise. We investigate with a scenario in there one carrier is assigned to only one user in each cell and construct a model for this problem. In this work, we apply the binary power control by the its simplification in the implemented algorithm for both uplink and downlink simultaneously to maximize sum data rate of the system. At first, we realize the 2-cells case separately to check the optimal power allocation whether being binary. Then, we carry on with N-cells case in general through properties of binary power control.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.8
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• pp.2648-2665
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• 2022

Device-to-device (D2D) multicast has become a promising technology to provide specific services within a small geographical region with a high data rate, low delay and low energy consumption. However, D2D multicast communications are allowed to reuse the same channels with cellular uplinks and result in mutual interference in a cell. In this paper, an intelligent channel assignment algorithm is designed in D2D underlaid cellular networks with the target of maximizing network throughput. We first model the channel assignment problem to be a throughput maximizing problem which is NP-hard. To solve the problem in a feasible way, a novel channel assignment algorithm is proposed. The key idea is to find the appropriate cellular communications and D2D multicast groups to share a channel without causing critical interference, i.e., finding a channel for a D2D multicast group which generates the least interference to network based on current channel assignment status. In order to show the efficacy and effectiveness of our proposed algorithm, a novel search algorithm is proposed to find the near-optimal solution as the baseline for comparisons. Simulation results show that the proposed algorithm improves the network throughput.

• BMB Reports
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• v.51 no.10
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• pp.493-499
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• 2018

Cellular senescence is a state of permanent cell-cycle arrest triggered by different internal and external stimuli. This phenomenon is considered to be both beneficial and detrimental depending on the cell types and biological contexts. During normal embryonic development and after tissue injury, cellular senescence is critical for tissue remodeling. In addition, this process is useful for arresting growth of tumor cells, particularly during early onset of tumorigenesis. However, accumulation of senescent cells decreases tissue regenerative capabilities and induces inflammation, which is responsible for cancer and organismal aging. Therefore cellular senescence has to be tightly regulated, and dysregulation might lead to the aging and human diseases. Among many regulators of cellular senescence, in this review, I will focus on microRNAs, small non-coding RNAs playing critical roles in diverse biological events including cellular senescence.