• The Journal of the Korea Contents Association
• /
• v.10 no.1
• /
• pp.46-58
• /
• 2010

The user valence of VoIP services with SIP protocol is increasing rapidly because of cheap communication cost and its conveniency. But attacker can easily modify the packet contents of SIP protocol as SIP header is transmitted by using UDP methods in text form. The reason is that SIP protocols does not provide an authentication function on the transmission session. Therefore, existing SIP protocol is very weak on SIP Packet Flooding attack etc. In order to solve like this kinds of SIP vulnerabilities, we used SIP status codes under the monitoring module for detecting SIP Flooding attacks and additionally proposed an advanced protocol where the authentication and security function is strengthened about SIP packet. We managed SIP session spontaneously in order to strengthen security with SIP authentication function and to solve the vulnerability of SIP protocol. The proposed mechanism can securely send SIP packet to solves the security vulnerability with minimum traffic transmission. Also service delay in SIP proxy servers will be minimized to solve the overload problem on SIP proxy server.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.8
• /
• pp.1114-1122
• /
• 2018

In this paper, we propose a theoretical framework for provisioning marginal resources in wired and wireless computer networks which include Internet. In more detail, we propose a mathematical model for the upper bounds of marginal capacity in grid networks, where the resource is designed a priori by normal traffic estimation and marginal resource is prepared for unexpected events such as natural disasters and abrupt flash crowd in public affairs. To be specific, we propose a method to evaluate an upper bound for minimum marginal capacity for an arbitrary grid topology using the concept of a strong Roman domination number. To that purpose, we introduce a graph theory to model and analyze the characteristics of general grid structure networks. After that we propose a new tight upper bound for the strong Roman domination number. Via a numerical example, we show the validity of the proposition.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.3
• /
• pp.821-830
• /
• 1997

The directory-based cache coherence scheme is an attractive approach to solve the caceh coherence problem in a large-scale shared-memory multiprocessor.However, the exsting directory-based schemes have some problens such as the enormous storage overhead for a directory, the long invalidation latency, the heavy network condes-tion, and the low scalability.For resolving these problems, we propose a new directroy- based caceh coherence scheme which is suitable for building scalable, shred-memory multiprocessors.In this scheme, each directory en-try ofr a given memory block is a number-balanced binaty tree(NBBT) stucture.The NBBT has several proper-ties to effciently maintain the directory for the cache consistency such that the shape is unique, the maximum depth is [log$_2$n], and the tree has the minimum number of leaf nodes among the binarry tree with n nodes.Therefore, this scheme can reduce the storage overhead, the network traffic, and the inbalidation latency and can ensutr the high- scalability the large-scale shared-memory multiprocessors.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.1
• /
• pp.17-25
• /
• 2017

Relocation and expansion of existing port facilities are necessary given this increase in marine traffic volume and the presence of larger entering vessels. Therefore, this study focused on anchorage among water facilities, and examined the degree of harmony between anchorage and other water facilities at Yeosu Kwangyang Port. The number of anchoring vessels in relation to anchorage over the past 5 years, total anchored hours by anchorage-years, average number of simultaneously anchored vessels by anchorage-years, maximum number of simultaneously anchored vessels by anchorage, and maximum size of anchored vessels by anchorage have been surveyed. The minimum anchorage radius has been calculated according to the designated anchorage capacity according to anchorage. Finally, improvement plans for Yeosu Kwangyang Port's anchorage have been suggested, including relocating of Yeosu no. 2 anchorage, expanding of Kwangyang no. 1 ~ 5 anchorage, relocating of Kwangyang no. 8 ~ 9 anchorage, and repealing of Kwangyang no. 11 anchorage.

• Wind and Structures
• /
• v.22 no.2
• /
• pp.211-234
• /
• 2016

Super long-span bridges provide people with great convenience, but they also bring traffic safety problems caused by strong wind owing to their high decks. In this paper, the large eddy simulation together with dynamic mesh technology in computational fluid dynamics (CFD) is used to explore the mechanism of a moving vehicle's transient aerodynamic force in crosswind, the regularity and mechanism of the vehicle's aerodynamic forces when it passes through a bridge tower's wake zone in crosswind. By comparing the calculated results and those from wind tunnel tests, the reliability of the methods used in the paper is verified on a moving vehicle's aerodynamic forces in a bridge tower's wake region. A vehicle's aerodynamic force coefficient decreases sharply when it enters into the wake region, and reaches its minimum on the leeward of the bridge tower where exists a backflow region. When a vehicle moves on the outermost lane on the windward direction and just passes through the backflow region, it will suffer from negative lateral aerodynamic force and yaw moment in the bridge tower's wake zone. And the vehicle's passing ruins the original vortex structure there, resulting in that the lateral wind on the right side of the bridge tower does not change its direction but directly impact on the vehicle's windward. So when the vehicle leaves from the backflow region, it will suffer stronger aerodynamic than that borne by the vehicle when it just enters into the region. Other cases of vehicle moving on different lane and different directions were also discussed thoroughly. The results show that the vehicle's pneumatic safety performance is evidently better than that of a vehicle on the outermost lane on the windward.

• Journal of Convergence for Information Technology
• /
• v.7 no.6
• /
• pp.135-141
• /
• 2017

Recently, as elderly people suffering from chronic diseases have increased and disasters such as traffic accidents have increased, urgent rescue workers and doctors need to respond effectively to such emergencies. For elderly people, the difficulty in communicating their condition especially the health condition during disaster is one of the problems in which delay on immediate handling by rescue team can cause death. Providing a solution for this problem is one of the main issues in our research. In this paper, we use the QR code to communicate the minimum personal information and medical history needed for emergency medical treatment to emergency medical personnel, and to transmit the medical history and treatment data to the doctors of the hospital through QR code and fingerprint recognition, respectively. Especially, by using both QR code of smart phone and fingerprint of individual, we can protects personal information and strengthens privacy and security of medical information by allowing only authorized physicians to check medical records of the old patient.

• Journal of Korean Foot and Ankle Society
• /
• v.5 no.1
• /
• pp.28-34
• /
• 2001

Study design: Clinical results were retrospectively analyzed in 11 patients with fractures of talar neck who were treated in our department from Jan. 1994 to Dec. 1999. Objective: The purpose of this study is to evaluate the short-term results and to assess the prognostic factors of talar neck fractures. Material and Method: 11 cases with fractures of talar neck were reviewed retrospectively with minimum 1 year follow-up. There were 8 men & 3 women, and the average age was 25. The most common cause was traffic accident. According to the modified Hawkins classification, type I was in 4 cases, type II in 5, type III in 2, and type IV was none. All type I fractures were treated conservatively, and others were treated operatively. Results: According to Hawkins criteria, there was excellent result in 7 cases(64%), good in 2(18%), and fair in 2(18%). Post-traumatic arthritis occurred in 2 cases, but there was no avascular necrosis. Conclusion: Careful selection of method of treatment and urgent management are important prognostic factors in talar neck fractures. The longer follow-up in more cases is necessary to evaluate the long-term clinical results and complications more accurately.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.479-482
• /
• 2011

This paper proposes a design of a ship backbone network-based on the survival and efficiency of the ship network. Currently IEC operates the standard ship network, a standard specification "IEC 61162-410 maintains the operation of the network. IEC 61162-410 offers a high stability of the ship network by using terminal equipment. But current studies are incomplete because it has been assumed that the ship's network will operate at double its current capacity. This paper analyzes the double ship backbone topology for an organization and then will summarise the minimum costs required to implement the ship backbone topology using an ILP. Also, we present an effective traffic assignment technique that uses an ILP, metaheuristic, heuristic algorism-based underlying the ship backbone network. The results by experimenting the design of the network confirmed a greter efficiency, stability and cost-effectiveness of the ship network.

• Journal of Navigation and Port Research
• /
• v.38 no.5
• /
• pp.493-501
• /
• 2014

An automated lifting vehicle(ALV) used in an automated container terminal is a type of unmanned vehicle that can self-lift a container as well as self-transport it to a destination. To operate a fleet of ALVs efficiently, one needs to be able to determine a minimum-time route to a given destination whenever an ALV is to start its transport job. To find a route free from any collision or deadlock, the occupation time of the ALV on each segment of the route should be carefully scheduled to avoid any such hazard. However, it is not easy because not only the travel times of ALVs are uncertain due to traffic condition but also the operation times of cranes en route are not predicted precisely. In this paper, we propose a routing method based on an ant colony optimization algorithm that takes into account these uncertainties. The result of simulation experiment shows that the proposed method can effectively find good routes under uncertainty.

• Journal of Information Processing Systems
• /
• v.13 no.5
• /
• pp.1229-1242
• /
• 2017

In this paper, an interference aware distributed multi-channel MAC (IDMMAC) protocol is proposed for wireless sensor and actor networks (WSANs). The WSAN consists of a huge number of sensors and ample amount of actors. Hence, in the IDMMAC protocol a lightweight channel selection mechanism is proposed to enhance the sensor's lifetime. The IDMMAC protocol divides the beacon interval into two phases (i.e., the ad-hoc traffic indication message (ATIM) window phase and data transmission phase). When a sensor wants to transmit event information to the actor, it negotiates the maximum packet reception ratio (PRR) and the capacity channel in the ATIM window with its 1-hop sensors. The channel negotiation takes place via a control channel. To improve the packet delivery ratio of the IDMMAC protocol, each actor selects a backup cluster head (BCH) from its cluster members. The BCH is elected based on its residual energy and node degree. The BCH selection phase takes place whenever an actor wants to perform actions in the event area or it leaves the cluster to help a neighbor actor. Furthermore, an interference and throughput aware multi-channel MAC protocol is also proposed for actor-actor coordination. An actor selects a minimum interference and maximum throughput channel among the available channels to communicate with the destination actor. The performance of the proposed IDMMAC protocol is analyzed using standard network parameters, such as packet delivery ratio, end-to-end delay, and energy dissipation, in the network. The obtained simulation results indicate that the IDMMAC protocol performs well compared to the existing MAC protocols.