• Journal of KIISE:Information Networking
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• v.37 no.4
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• pp.301-306
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• 2010

We propose the control channel access scheme for multi-interface multi-hop cognitive radio (CR) environment having a cluster structure. Due to the difficulty of obtaining common channels across the entire CR network, most multi-interface multi-hop CR networks put the control channel outside the CR bandwidth and dedicate one network interface to it in order to exchange the control information such as the activation of licensed users. However, this will be the waste of the network interface. Our focus is how to alternate between the control and the data channel without multichannel hidden node problem under the cluster structure where CR nodes connect with neighbors through multiple data channels. By using simulation, we evaluate the performance of the proposed scheme. The results show that the proposed scheme achieves higher network throughput than the dedicated scheme where one network interface card should dedicate to the control channel and cannot be used for data transmission.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.9
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• pp.3274-3297
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• 2021

Permission delegation is an important research issue in access control. It allows a user to delegate some of his permissions to others to reduce his workload, or enables others to complete some tasks on his behalf when he is unavailable to do so. As an ideal solution for controlling read access on outsourced data objects on the cloud, Ciphertext-Policy Attribute-Based Encryption (CP-ABE) has attracted much attention. Some existing CP-ABE schemes handle the read permission delegation through the delegation of the user's private key to others. Still, these schemes lack the further consideration of granularity and traceability of the permission delegation. To this end, this article proposes a flexible and fine-grained CP-ABE key delegation approach that supports white-box traceability. In this approach, the key delegator first examines the relations between the data objects, read permission thereof that he intends to delegate, and the attributes associated with the access policies of these data objects. Then he chooses a minimal attribute set from his attributes according to the principle of least privilege. He constructs the delegation key with the minimal attribute set. Thus, we can achieve the shortest delegation key and minimize the time of key delegation under the premise of guaranteeing the delegator's access control requirement. The Key Generation Center (KGC) then embeds the delegatee's identity into the key to trace the route of the delegation key. Our approach prevents the delegatee from combining his existing key with the new delegation key to access unauthorized data objects. Theoretical analysis and test results show that our approach helps the KGC transfer some of its burdensome key generation tasks to regular users (delegators) to accommodate more users.

• Journal of Communications and Networks
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• v.13 no.2
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• pp.102-112
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• 2011

In this paper, we propose a privacy-preserving emergency call scheme, called PEC, enabling patients in life-threatening emergencies to fast and accurately transmit emergency data to the nearby helpers via mobile healthcare social networks (MHSNs). Once an emergency happens, the personal digital assistant (PDA) of the patient runs the PEC to collect the emergency data including emergency location, patient health record, as well as patient physiological condition. The PEC then generates an emergency call with the emergency data inside and epidemically disseminates it to every user in the patient's neighborhood. If a physician happens to be nearby, the PEC ensures the time used to notify the physician of the emergency is the shortest. We show via theoretical analysis that the PEC is able to provide fine-grained access control on the emergency data, where the access policy is set by patients themselves. Moreover, the PEC can withstandmultiple types of attacks, such as identity theft attack, forgery attack, and collusion attack. We also devise an effective revocation mechanism to make the revocable PEC (rPEC) resistant to inside attacks. In addition, we demonstrate via simulation that the PEC can significantly reduce the response time of emergency care in MHSNs.

• Journal of KIISE:Databases
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• v.37 no.3
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• pp.171-175
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• 2010

This paper analyzes the tag data inconsistency problem caused by incomplete execution of the tag access operation to the RFID tag's memory and proposes a protocol to control consistent tag data accesses with finalizing the incomplete operation. Passive RFID tag cannot guarantee complete execution of the tag access operations because of uncertainty and unexpected disconnection of RF communications. This leads to the tag data inconsistency problem. To handle this, we propose a concurrency control protocol which defines incomplete tag operations as continuous queries and monitors the tags're-observation continuously. The protocol finalizes the incomplete operation when the tag is re-observed while it blocks inconsistent data accesses from other operations. We justify the proposed protocol by analyzing the completeness and consistency. The experiments show that the protocol shows better performance than the traditional lock-based concurrency control protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.323-329
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• 2018

In this paper, we implemented an access control system that only allows specific users to use documents in Hangul document system. The system structure designed in this paper is to transform header information of Hangul document by analyzing the structure of Hangul document. By modifying the function of a specific field of the header information in Hangul document, it prevents users that do not have data for the modified information to open and view the document. By controlling the access rights to important Hangul documents, it is possible to manage Hangul files more safely. In this paper, the actual design of information was implemented and experiments were carried out. Results of the experiment confirmed that the access control system is operated in normal way. In this paper, we implemented an access control system that only allows specific users to use documents in Hangul document system.

• Convergence Security Journal
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• v.11 no.4
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• pp.43-49
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• 2011

Web-based health information provides a lot of conveniences, however the security vulnerabilities that appear in the network environment without the risk of exposure in the use of information are growing. Web-based medical information security issues when accessing only the technology advances, without attempting to seek a safe methodology are to increase the threat element. So it is required. to take advantage of web-based information security measures as a web-based access control security mechanism-based design. This paper is based on software architecture, design, ideas and health information systems were designed based on access control security mechanism. The methodologies are to derive a new design procedure, to design architecture and algorithms that make the mechanism functio n. To accomplish this goal, web-based access control for multiple patient information architecture infrastructures is needed. For this software framework to derive features that make the mechanism was derived based on the structure. The proposed system utilizes medical information, medical information when designing an application user retrieves data in real time, while ensuring integration of encrypted information under the access control algorithms, ensuring the safety management system design.

• Smart Media Journal
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• v.12 no.7
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• pp.27-42
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• 2023

The development of cloud services and IoT technology has radically changed the cloud environment, and has evolved into a new concept called fog computing and F2C (fog-to-cloud). However, as heterogeneous cloud/fog layers are integrated, problems of access control and security management for end users and edge devices may occur. In this paper, an F2C-based IoT smart health monitoring system architecture was designed to operate a medical information service that can quickly respond to medical emergencies. In addition, a role-based service access control technology was proposed to enhance the security of user's personal health information and sensor information during service interoperability. Through simulation, it was shown that role-based access control is achieved by sharing role registration and user role token issuance information through blockchain. End users can receive services from the device with the fastest response time, and by performing service access control according to roles, direct access to data can be minimized and security for personal information can be enhanced.

• Journal of the Korea Society of Computer and Information
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• v.29 no.9
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• pp.115-123
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• 2024

This paper proposes a method to reduce the delay time caused by control message conflicts in VADAMA (Virtual Allocation Demand Assigned Multiple Access) technology, which is a virtual allocation based on-demand multiple access technology in MF-TDMA (Multi-Frequency Time Division Multiple Access) satellite network. Traditionally, satellite networks have had the problem that all network transmissions have long delay times due to control messages. In this study, in order to improve the delay time caused by terminal control message conflicts in VADAMA technology, the concept of virtual allocation is used to reduce the delay time. VADAMA-PTR (VADAMA Periodic Transmission) divides all terminals into subnets and transmits control. The method is proposed, and the performance analysis of the existing DAMA technology, delay time and data processing rate is performed using Matlab. The results show that the performance is improved.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.275-285
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• 2015

To improve the efficiency of carrier sense multiple access (CSMA)-based medium access control (MAC) protocols, CSMA with collision resolution (CSMA/CR) has been proposed. In the CSMA/CR, a transmitting station can detect a collision by employing additional sensing after the start of a data transmission and then resolve the next collision that might occur by broadcasting a jam signal during a collision detection (CD) period. In this paper, we analyze the delay of a CSMA/CR based on a generic p- persistent CSMA model and obtain the minimum achievable delay of the CSMA/CR by finding the optimal length of the CD period according to the number of contending stations. Through this delay analysis, we also investigate the throughput-delay characteristics of the CSMA/CR protocol according to various parameters. Analysis and simulation results show that the CSMA/CR has a considerably lower delay and its throughput-delay characteristic is significantly improved than the conventional CSMA/CA and wireless CSMA/CD protocols.

• Journal of information and communication convergence engineering
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• v.5 no.2
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• pp.93-97
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• 2007

In this paper, centralized access control and slot allocation algorithm is proposed for wireless networks. The proposed algorithm is characterized by the contention-based reservation. In order to reduce the collision probability of reservation request, the base station calculates and broadcasts the transmission probability of reservation requests, and the wireless terminal transmits its reservation request with the received transmission probability. The scheduler allocates the uplink data slots based on the successful reservation requests. Simulation results show that the proposed algorithms can provide high channel utilization, and furthermore, maintains constant delay performance in the heavy traffic environment.