• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.389-399
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• 1998

The DMR-II shared-medium access control protocol was developed for the ATM access network users to supper the isochronous traffic and the non-isochronous traffic simultaneously under the bandwidth-skating environment. In this paper we analyze the performance of the DMR-II protocol by using both the analytical analysis and the simulation method. Under the ATM access network environment, the performance analysis result shows that the DMR-II protocol maintains the delay variation of the isochronous traffic beyond the threshold value, and satisfies the delay time criteria of the non-isochronous traffic by supporting the priority service. Moreover the result shows high network utilization over 130% due to the destination release mechanism of the DMR-II protocol.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.236-246
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• 2007

This paper investigates the performance of the transmission control protocol (TCP) transport protocol over IEEE 802.11 infrastructure based wireless networks. A wireless link is generally characterized by high transmission errors, random interference and a varying latency. The erratic packet losses usually lead to a curbing of the flow of segments on the TCP connection and thus limit TCP's performance. This paper examines the impact of the lossy nature of IEEE 802.11 wireless networks on the TCP performance and proposes a scheme to improve the performance of TCP over wireless links. A negative acknowledgment scheme, selective negative acknowledgment (SNACK), is applied on TCP over wireless networks and a series of ns-2 simulations are performed to compare its performance against that of other TCP schemes. The simulation results confirm that SNACK and its proposed enhancement SNACK-S, which incorporates a bandwidth estimation model at the sender, outperform conventional TCP implementations in 802.11 wireless networks.

• Journal of Korean Clinical Nursing Research
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• v.20 no.2
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• pp.223-235
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• 2014

Purpose: Resuscitation rooms in emergency department are places for time-critical tasks. This study aimed 1) to develop a resuscitation protocol for dyspneic patients and 2) to evaluate the effect of the resuscitation protocol for dyspneic patients in improving clinical performances. Methods: A panel of experts including emergency physicians and nurses developed a resuscitation protocol for dyspneic patients which included a list of critical interventions and time-limits. The resuscitation protocol was implemented in a emergency medical center for two months. Clinical performances of health care providers were compared by analyzing video-recorded clinical performances. Results: The resuscitation protocol consisted of four steps: Initial treatments within 5 minutes, main treatments within 15 minutes, diagnostic tests within 30 minutes, and disposition within 60 minutes. A total of 43 dyspneic patients (23 patients experimental group, 20 patients control group) were included for the analysis of the clinical performance change. Clinical performance rates were improved significantly from control group (66.71%) to experimental group (82.41%) after implementing the resuscitation protocol (Z=-3.09, p=.004). Conclusion: The resuscitation protocol developed for dyspneic patients improved clinical performance rates of health care providers. Further development of clinical protocols for other emergent cases at resuscitation rooms are strongly recommended.

• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.59-70
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• 2014

This paper propose a new wireless multi-hop routing protocol that takes the hierarchical mesh of the hybrid WMN into account. WMN that is possible to provide various applications of wireless networks still has many open issues that should be solved despite the studies carried out over a decade. Especially, in routing protocol area, a problem degrading the routing efficiency by applying one of the routing protocols, which are designed for the MANET, to the hybrid WMN be solved above all. For the improvement of the routing performance, both good routing protocol and metric are essential. However, the recent studies are only concentrated in routing metric by use of the cross-layer design. Therefore, this paper is dedicated to the routing protocol that is essential for the performance of the routing but needed more studies. The proposed protocol in this paper is reactive, and designed to reorganize the hybrid WMN with several pseudo domains, and carry out domain-based route decision. By the simulation result for the performance analysis of the proposed protocol, the average delay for the route decision was decreased by 43% compared to AODV that is the typical reactive protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6B
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• pp.585-594
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• 2009

Efficient filtering is an important factor in RFID system performance. Because of huge volume of tag data in future ubiquitous environment, if RFID readers transmit tag data without filtering to upper-layer applications, which results in a significant system performance degradation. In this paper, we provide an efficient filtering technique which operates on RFID air protocol. RFID air protocol filtering between tags and a reader has some advantages over filtering in readers and middleware, because air protocol filtering reduces the volume of filtering work before readers and middleware start filtering. Exploiting the air protocol filtering advantage, we introduce a geometrical algorithm for generating air protocol filters and verify their performance through simulation with analytical time models. Results of dense RFID reader environment show that air protocol filtering algorithms reduce almost a half of the total filtering time when compared to the results of linear search.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1A
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• pp.50-57
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• 2009

Tag collection is one of the major functions in RFID systems. In this paper, we propose a multichannel slotted-aloha anticollision protocol to mitigate the tag collision problem and improve tag collection performance in active RFID systems. In the proposed anticollision protocol, while an RFID reader transmits commands to multiple RFID tags via a common channel, it receives multiple tag responses over multiple channels simultaneously. We also implemented an active RFID system supporting the proposed anticollision protocol. In experiments with the implemented reader and 60 tags, the proposed dual-channel slotted-aloha anticollision protocol showed a large improvement in tag collection performance compared with the single-channel slotted-aloha anticollision protocol. With 60 tags, the average time spent on tag collection using the dual-channel anticollision protocol was 600.543 ms, which was 46.3% of the 1289.721 ms required using the single-channel anticollision protocol.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.685-690
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• 2006

This paper compares the performance of the unicast routing protocol and the broadcast routing protocol in a small-sized wireless multi-hop network, such as home network. Normally, ad-hoc routing protocols are designed for general wireless multi-hop networks, not being said to be optimized for the small-sized ad hoc network. This paper compares some unicast routing protocols and optimal broadcast routing protocol, and shows the result. The result of the simulation says the broadcast routing protocol shows better performance than the ad-hoc routing protocols in the small-sired wireless multi-hop network. Especially, the result shows that the broadcast protocol has higher packet delivery ratio and lower packet latency than unicast routing protocols

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.1005-1014
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• 2010

When reader collect tags, we found that they tend to get together to specific interface in Multi-Interface Multi-Channel 2.4GHz Active RFID system. To solve this problem, we designed the LP-Combind and AP-Balanced protocol for load distribution between interfaces, then verified its superiority of the performance through the simulation. There are three problems to implement designed protocols in hardware of firmware-level. first, tag selects randomly the channel of reader and reader need the method which can change the channel of tags. second, reader has the synchronization problem between reader and tag. third, reader has problem that MCU of reader have to operate simultaneously dual interface. To slove this problems, we designed the message and implemented method for tag channel change and the protocol in order to adjust synchronization between reader and tag, Therefore, we compared and analyzed the performance of protocols by experiment. If LP windows size is same, the performance of LP-Combined protocol and AP-Balanced protocol which lower collision probability by its load distribution is more outstanding than single interface protocol performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.955-963
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• 2022

The Internet of Things (IoT), combined with various technologies, is rapidly becoming an integral part of our daily life. While it is rapidly taking root in society, security considerations are relatively insufficient, making it a major target for cyber attacks. Since all devices in the IoT environment are connected to the Internet and are closely used in daily life, the damage caused by cyber attacks is also serious. Therefore, encryption communication using a network security protocol must be considered for a service in a more secure IoT environment. A representative network security protocol includes TLS (Transport Layer Protocol) defined by the IETF. This paper analyzes the performance measurement results for TLS version 1.2 and version 1.3 in an IoT device open platform environment to predict the load of TLS, a representative network security protocol, in IoT devices with limited resource characteristics. In addition, by analyzing the performance of each major cryptographic algorithm in version 1.3, we intend to present a standard for setting appropriate network security protocol properties according to IoT device specifications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.470-473
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• 2002

Most networks for automation are tuned to an expected traffic at their design stage. During their actual operations, however, the networks experience considerable changes in traffic from time to time. These traffic changes caused by common events like machine failure and production schedule change may adversely affect the network performance and, in turn, the performance of the connected devices. This paper presents communication delay model for Profibus token passing protocol, and introduces TTR selection methods to maintain a uniform level of network performance at all stations under changing network traffic.