• International Journal of Computer Science & Network Security
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• v.21 no.9
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• pp.132-140
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• 2021

Under the mobile ad-hoc network system, the main reason for causing congestion is because of the limited availability of resources. On the other hand, the standardised TCP based congestion controlling mechanism is unable to control and handle the major properties associated with the shared system of wireless channels. It creates an effect on the design associated with suitable protocols along with protocol stacks through the process of determining the mechanisms of congestion on a complete basis. Moreover, when bringing a comparison with standard TCP systems the major environment associated with mobile ad hoc network is regraded to be more problematic on a complete basis. On the other hand, an agent-based mobile technique for congestion is designed and developed for the part of avoiding any mode of congestion under the ad-hoc network systems.

• The Journal of the Korea Contents Association
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• v.8 no.8
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• pp.57-64
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• 2008

In this paper, to resolve the problem caused by a network state information inaccuracy the slow delay time that conclusion of network state of one way delay time which accuracy delay time information, according to network state changes on the based TFRC flow control, and suggest that flow control mechanism to adjust transfer rate fit of real time multimedia data. In simulation, to measure of netowork state information that on the average about 12% difference of compared RTT and $OWD{\times}2$. When used RTT, used fair bandwidth TFRC much better than TCP about 32%, when used OWD, difference about 3% used fair bandwidth. Thus, conclusion of accuracy network state that used fair bandwidth according to network state changes on the based TFRC, users can support service of high quality that flow control mechanism to adjust transfer rate fit of real time data.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.618-624
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• 2008

Various calcium phosphate bioceramics are distinguished by their excellent biocompatibility and osteoconductivity. Especially, the exceptional biodegradability of $\beta$-TCP makes it a bone graft substitute of choice in many clinical applications. The activation of osteoclasts, differentiated from macrophage precursor cells, trigger a cell-mediated resorption mechanism that renders $\beta$-TCP biodegradable. Based on this evidence, we studied the biodegradation process of granular-type $\beta$-TCP bone graft substitute through in vitro and in vivo studies. Raw 264.7 cells treated with RANKL and M-CSF differentiated into osteoclasts with macrophage-like properties, as observed with TRAP stain. These osteoclasts were cultured with $\beta$-TCP nano powders synthesized by microwave-assisted process. We confirmed the phagocytosis of osteoclasts by observing $\beta$-TCP particles in their phagosomes via electron microscopy. No damage to the osteoclasts during phagocytosis was observed, nor did the $\beta$-TCP powders show any sign of cytotoxicity. We also observed the histological changes in subcutaneous tissues of rats implanted with granule-type $\beta$-TCP synthesized by fibrous monolithic process. The $\beta$-TCP bone graft substitute was well surrounded with fibrous tissue, and 4 months after implantation, 60% of its mass had been biodegraded. Also, histological findings via H&E stain showed a higher level of infiltration of lymphocytes as well as macrophages around the granule-type $\beta$-TCP. From the results, we have concluded that macrophages play an important role in the biodegradation process of $\beta$-TCP bone graft substitutes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.6
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• pp.575-596
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• 2009

Facing limited network resources such as bandwidth and processing capability, the Internet will have congestion from time to time. In this paper, we propose a scheme to maximize the total utility offered by the network to the end user during congested times. We believe the only way to achieve our goal is to make the scheme application-aware, that is, to take advantage of the characteristics of the application. To make our scheme scalable, it is designed to be class-based. Traffic from applications with similar characteristics is classified into the same class. We adopted the RED queue management mechanism to adaptively control the traffic belonging to the same class. To achieve the optimal utility, the traffic belonging to different classes should be controlled differently. By adjusting link bandwidth assignments of different classes, the scheme can achieve the goal and adapt to the changes of dynamical incoming traffic. We use the control theoretical approach to analyze our scheme. In this paper, we focus on optimizing the control on two types of traffic flows: TCP and Simple UDP (SUDP, modeling audio or video applications based on UDP). We derive the differential equations to model the dynamics of SUDP traffic flows and drive stability conditions for the system with both SUDP and TCP traffic flows. In our study, we also find analytical results on the TCP traffic stable point are not accurate, so we derived new formulas on the TCP traffic stable point. We verified the proposed scheme with extensive NS2 simulations.

• The KIPS Transactions:PartC
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• v.10C no.5
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• pp.595-602
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• 2003

In this paper, we proposed new buffer management and cell scheduling scheme of GFR service for improving fairness of TCP/IP traffic in ATM networks. The proposed algorithm used untagged cell, which came to ATM switch, to decide the policy for discard of frame and what kind of VC cell it would serve. Performance analysis through the simulation present that proposed scheme can meet fairness 2 (MCR Plus equal share), which are not met by conventional scheduling mechanism such as WRR. Also, proposed scheme is superior to WRR about 30% in throughput and more efficiency in fairness criteria.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2003.05a
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• pp.311-315
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• 2003

Recently, there is asymmetrical transmission in Internet data stream. The asymmetrical transmission has much more downstream than upstream. Owing to this point, it needs to reduce the acknowledgement as element of the obsrtuction in downstream. In this paper, according to simulation's result, we know that Sack has good performance than New Reno in bottleneck environment Comparing two protocols in packet loss rate, NewReno is lower than Sack. And also comparing two protocols in throughput of ack packet, not only NewReno processes ack packet more quickly than Sack, but also NewReno processes more ack packet than Sack protocol during ten seconds in simulation. As a result, NewReno is batter than Sack in throughput of asymmetrical link.

• Journal of Advanced Navigation Technology
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• v.14 no.3
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• pp.358-366
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• 2010

In the wireless network the congestion and delay occurs mainly when there are too many packets for the network to process or the sender transmits more packets than the receiver can accept. The congestion and delay is the reason of packet loss which degrades the performance of multimedia streaming. This paper proposes a novel transmission rate monitoring-based optimization mechanism to optimize packet loss and to improve QoS. The proposed scheme is based on the trade-off relationship between transmission rate monitoring and overhead monitoring. For this purpose this paper processes a source rate control-based optimization which optimizes congestion and delay. Performance evaluated RED, TFRC, and the proposed mechanism. The simulation results show that the proposed mechanism is more efficient than REC(Random Early Detection) mechanism and TFRC(TCP-friendly Rate Control) mechanism in packet loss rate, throughput rate, and average response rate.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.764-775
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• 2003

Previous works for the assured service in the Diffserv network have no sufficient consideration on the fairness of bandwidth share based on RTTs and the target rates of TCP flows. In this paper, in order to solve these problems, we propose a TRA3CM(Target rate and RTT Aware 3 Color Marking) mechanism. The TRA3CM mechanism provides three color marking and fair transmission rates among aggregate flows by considering RTT and target rate simultaneously. In case of higher target rate than bottleneck bandwidth, the TRA3CM mechanism is able to mitigate the RTT effect and provides fair transmission rates. In the results of comparing the performance among existing mechanisms and the TRA3CM, the TRA3CM mechanism was able to mitigate the RTT effect better than the former. The TRA3CM is shown to provide good performance for transmission rates proportional to various target rates.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.11
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• pp.635-642
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• 2004

The traditional communication protocols such as TCP/IP are not suitable for PC cluster systems because of their high software processing overhead. To eliminate this overhead, industry leaders have defined the Virtual Interface Architecture (VIA). VIA provides two different data transfer mechanisms, a traditional Send/Receive model and the Remote Direct Memory Access (RDMA) model. RDMA is extremely efficient way to reduce software overhead because it can bypass the OS and use the network interface controller (NIC) directly for communication, also bypass the CPU on the remote host. In this paper, we have implemented VIA-based RDMA mechanism in hardware. Compared to the traditional Send/Receive model, the RDMA mechanism improves latency and bandwidth. Our RDMA mechanism can also communicate without using remote CPU cycles. Our experimental results show a minimum latency of 12.5${\mu}\textrm{s}$ and a maximum bandwidth of 95.5MB/s. As a result, our RDMA mechanism allows PC cluster systems to have a high performance communication method.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.966-969
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• 2007

In this paper, we propose a novel probing mechanism for adaptive transmission of video data based on congestion control and client state. The proposed mechanism is friendly to the network dominant transport protocols (TCP) and can reduce fluctuations compared to the previous works.