• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3447-3469
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• 2019

It is well-known that the cooperative communication and error control technology can improve the network performance, but most existing cooperative MAC protocols have not focused on how to cope with the contention process caused by cooperation and how to reduce the bad influence of channel packet error rate on the system performance. Inspired by this, this paper first modifies and improves the basic rules of the IEEE 802.11 Medium Access Control (MAC) protocol to optimize the contention among the multi-relay in a cooperative ARQ scheme. Secondly, a hybrid ARQ protocol with soft combining is adopted to make full use of the effective information in the error data packet and hence improve the ability of the receiver to decode the data packet correctly. The closed expressions of network performance including throughput and average packet transmission delay in a saturated network are then analyzed and derived by establishing a dedicated two-dimensional Markov model and solving its steady-state distribution. Finally, the performance evaluation and superiority of the proposed protocol are validated in different representative study cases through MATLAB simulations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.603-606
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• 2019

In this paper, we propose a slotted-ALOHA-based random access protocol and derive the optimal number of random slots that maximize channel throughput when multiple energy harvesting sensor devices perform random access in wireless-powered sensor networks (WPSN). Throughput numerical analysis, we prove that the throughput has a concavity with respect to the number of random slots and obtain the optimal number of slots. Simulation results show that the throughput of the proposed slotted ALOHA-based random access protocol is maximize when the derived optimal number of slots is employed in the considered WPSN.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.17-27
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• 2005

With the development of wire and wireless based networks, a various security protocols have been proposed to protect important resources and user information against attackers. However, many security protocols have found oかy to be later vulnerable to attacks. In this Paper, we introduce the formal methodology to verify the safety of security protocols in the design phase, and we take advantage of the formal methodology which uses Casper/CSP and FDR tools by introducing the verification example of EKE protocol and BCY protocol. Lastly, we propose a new BCY protocol after verifying it's safety.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.327-333
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• 2022

Internet Protocol Television (IPTV) has emerged as a personal entertainment source for home users. Streaming IPTV content over a wireless medium with good Quality of Service (QoS) can be a challenging task as IPTV content requires more bandwidth and Wireless Local Area Networks (WLANs) are susceptible to packet loss, delay and jitter. This research presents the capacity of IPTV using User Datagram Protocol (UDP) and TCP Friendly Rate Control (TFRC) over IEEE 802.11ac WLANs in good and bad network conditions. Experimental results show that in good network conditions, UDP and TFRC could accommodate a maximum of 78 and 75 Standard Definition Television (SDTV) users, respectively. In contrast, 15 and 11 High-Definition Television (HDTV) users were supported by UDP and TFRC, respectively. Performance of UDP and TFRC was identical in bad network conditions and same number of SDTV and HDTV users were supported by TFRC and UDP. With background Transmission Control Protocol (TCP) traffic, both UDP and TFRC can support nearly the same number of SDTV users. It was found that TFRC can co-exist fairly with TCP by giving more throughput to TCP unlike UDP.

• The Journal of Korean Academic Society of Nursing Education
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• v.3 no.2
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• pp.193-206
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• 1997

Because the oral mucositis is often inevitable in acute leukemia patients during chemotherapy, the efforts must be made to keep these leukemia patients from oral mucositis. So we tried to develop two oral care protocols for reducing the level of oral mucositis during cytotoxic therapy through literature review and our clinical experience. This quasi-experimental study was performed to compare the prohpylatic value of these oral care protocols. Thirty-nine subjects were assigned to one of three groups. The first group performed bivon-normal saline gargling protocol, the second group performed chlorhexidine gargling protocol, and the last contrast group kept traditonal gargling protocol. The Oral Assessment Guide(OAG), the Beck's perception of oral comfort were used to assess oral status and subject's oral discomfort during chemotherapy. Each subjects were observed daily from the start of the chemotherapy until Absolute Neutrophil Count (ANC) reached $1,000/mm^3$. It continued about 2-4 weeks. The data was analyzed by ANCOVA and Kruskal-Wallis one way ANOVA, chi-sqare, survival analysis. The results were as follows : The contrast group showed significantly highest mean score of the OAG and Beck's perception of oral discomfort among three groups from second week to third week. However chie-test and survial analysis showed that the incidence of severe mucositis were not significantly different among three groups. Conclusively we recommend that nurses who care acute leukmia patients use bivon-normal saline gargling protocol be careful to occur severe mucositis during chemotherapy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2348-2356
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• 1997

This paper describes a method of AAL(SSCOP) protocol conformance testing and its result analysis in ATM network. Terminal equipment(TE) that implements protocols for connecting ATM network shall be verified if appropriately implement by conformance testing. The protocol specifications and the testing methodology are recommended or standardized by international standardization organization(ITU-T, ISO, etc.). The ATM AAL (SSCOP) protocol which selected for describing conformance test procedure is standardized in ITU-T Q.2110 and ATM Forum UNI 3.1 which are same in contents. Also Testing standard like ATS for SSCOP is specified in ATM Forum 95-1459R2. Construction of conformance testing environment is necessary to coordinate in relations with standards, then testing must beexecuted at that environment and the results from the test system analyzed. For this, it is necessary to select any test case from standard for testing and to make ETS. The ETS is proted on the test system and conformance testing will execute on that system. Finally the result from the test system is to analyze. This conformance testing procedure is applicable to the same other test cases in SSCOP and protocols in any communcation networks.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.126-134
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• 2012

The researchers of this study closely looked into the methods for cognitive-scientific approach to problems of marine design at a time when the overall values of marine cultures are acknowledged in full scale. To that end, the researchers analyzed the problems and problem-solving process for the initial approach to marine design. At the same time, the researchers made the matrix of the design-developmental directions by cognitive scientific approach. After selecting the subjects, the researchers collected verbal protocol and behavior protocol which were shown in the process of a designer's thinking. This was for the sake of protocol analysis which is the representative research technique of cognitive science. Based on the collected data, the researchers empirically analyzed the behavior patterns shown in the marine design process so as to develop the design behavior-graph pattern of designers in an objective and systematic way. The behavior graph was helpful for looking into the initial developmental directions of design and for predicting cognitive structure of designers. The researchers hope that this study will become a fundamental material for predicting cognitive directions of designer for planning and designing the marine design.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.897-910
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• 2012

Inappropriate communications can cause a lack of necessary information exchange between operators and lead to serious consequences in large process systems such as nuclear power plants (NPPs). In this regard, various kinds of taxonomies of inappropriate communications have been developed to prevent inappropriate communications. However, there seems to be difficult to identify inappropriate communications from verbal protocol data between operators. Because the existing taxonomies were developed for use in report analysis, there is a problem of 'uncertainty'. In consequence, this paper proposes a new taxonomy of inappropriate communications and provides some insights to prevent inappropriate communications. In order to develop the taxonomy, existing taxonomies for four industries from 1980 to 2010 were collected and a new taxonomy is developed based on the simplified one-way communication model. In addition, the ratio of inappropriate communications from 8 samples of audio-visual format verbal protocol data recorded during emergency training sessions by operating teams is compared with performance scores calculated based on the task analysis. As a result, inappropriate communications can be easily identified from the verbal protocol data using the suggested taxonomy, and teams with a higher ratio of inappropriate communications tend to have a lower performance score.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1083-1092
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• 2016

In this paper, the performance of the optical code-division multiple access (OCDMA) technology on a plastic optical fiber (POF) access network, which had received much attention due to its low weight, large core diameter, flexibility, easy installation, and especially its high bandwidth, is analyzed. Recently, POF was a very attractive candidate for transmission media in an access network based on OCDMA technology. But the conventional OCDMA system only allows finite units to transmit and access simultaneously according to the number of channels which are restricted by BER, and so, in this paper, to resolve this problem a novel multi-priority reservation protocol is also proposed. By using this reservation scheme and a distributed arbitration algorithm, channel collision and destination conflict could be avoided. And this protocol can efficiently support the transmission of multimedia messages that require the different time-delay. The network throughput and average delay using various system parameters have been investigated by numerical analysis and simulation experiments. These results shows that the multi-priority reservation protocol in this POF access network based on OCDMA technology is valid and efficient.

• Convergence Security Journal
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• v.23 no.4
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• pp.43-52
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• 2023

Many businesses and organizations use smartcard-based user authentication for remote access. In the meantime, through various studies, dynamic ID-based remote user authentication protocols for distributed multi-server environments have been proposed to protect the connection between users and servers. Among them, Qiu et al. proposed an efficient smart card-based remote user authentication system that provides mutual authentication and key agreement, user anonymity, and resistance to various types of attacks. Later, Andola et al. found various vulnerabilities in the authentication scheme proposed by Qiu et al., and overcame the flaws in their authentication scheme, and whenever the user wants to log in to the server, the user ID is dynamically changed before logging in. An improved authentication protocol is proposed. In this paper, by analyzing the operation process and vulnerabilities of the protocol proposed by Andola et al., it was revealed that the protocol proposed by Andola et al. was vulnerable to offline smart card attack, dos attack, lack of perfect forward secrecy, and session key attack.