• International Journal of Computer Science & Network Security
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• v.21 no.7
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• pp.331-340
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• 2021

The Internet of Things (IoT) is a rapidly growing physical network that depends on objects, vehicles, sensors, and smart devices. IoT has recently become an important research topic as it autonomously acquires, integrates, communicates, and shares data directly across each other. The centralized architecture of IoT makes it complex to concurrently access control them and presents a new set of technological limitations when trying to manage them globally. This paper proposes a new decentralized access control architecture to manage IoT devices using blockchain, that proposes a solution to concurrency management problems and enhances resource locking to reduce the transaction conflict and avoids deadlock problems. In addition, the proposed algorithm improves performance using a fully distributed access control system for IoT based on blockchain technology. Finally, a performance comparison is provided between the proposed solution and the existing access management solutions in IoT. Deadlock detection is evaluated with the latency of requesting in order to examine various configurations of our solution for increasing scalability. The main goal of the proposed solution is concurrency problem avoidance in decentralized access control management for IoT devices.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.57-64
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• 2005

While the secure concurrency control schemes in multilevel secure database management systems synchronize transactions cleared at different security level they must consider the problem covert channel. although previous works achieve the confidentiality successfully, they overlook the integrity or the availability. For being evaluated as highly secure database systems , the multilevel secure database management systems must achieve the confidentiality, integrity, and the availability that are the well-known major security aspects. By use of verified transactions ordering relationship, in this Paper, we Propose a new secure concurrency control scheme that is capable of increasing the degree of fairness among transactions cleared at different security levels.

• Journal of the Korea Society for Simulation
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• v.12 no.2
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• pp.13-24
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• 2003

In this study, we propose a scheduling analysis method of the Flexible management system using the transitive matrix. The Scheduling problem is a combination-optimization problem basically, and a complexity is increased exponentially for a size of the problem. To reduce an increase of a complexity, we define that the basic unit of concurrency (short BUC) is a set of control flows based on behavioral properties in the net. And we propose an algorithm to divide original system into some BUC. To sum up, we divide a petri net model of the Flexible management system Into the basic unit of concurrency through the division algorithm using the transitive matrix. Then we apply it to the division-scheduling algorithm to find an efficient scheduling. Finally, we verify its efficiency with an example.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.1-7
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• 2001

The database development is in need or transaction management composed of operations about data, efficiency database management and security of information data in necessity of as well as the new thinking about data security. When users approach data, transaction concurrency is controlled by the users security authentication and security level of data. So, existing secure algorithm occurred the problems which don't satisfy serializability of high level transaction which is delayed high level transaction repeatedly by the low level transaction, because existing secure algorithm is focused on the part which removes the security channel. Therefore this proposed algorithm which prevents waste of resource from the high level transaction reexecution and delay by stopping serializability offense problem by the increase of efficiency of concurrency control.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.62-65
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• 2002

The locking is the most widely-used concurrency control mechanism for guaranteeing logical consistency of a database where a number of transactions perform concurrently. In this Paper, we propose a new method for lock management appropriate in main-memory databases. Our method chooses the partition, a fixed-sized container for records. as a unit of locking. and directly keeps lock information within the Partition itself. These make our method enjoy the following advantages: (1) it has freedom in controlling of the trade-off between the system concurrency and the lock processing overhead by considering the characteristics of given target applications. (2) it enhances the overall system performance by eliminating the hashing overhead, a serious problem occurred in the traditional method.

• Asia pacific journal of information systems
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• v.5 no.1
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• pp.219-235
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• 1995

Complexity of some problems often transcends the problem solving capability of human individuals. As such, we cannot but take a collaborative approach to those complex problems. Collaboration while using computing systems can take place through shared objects. However, current commercial DBMSs do not provide a satisfactory control for concurrent access to objects shared by collaborators. A new concurrency control scheme is proposed which will help a group of people work in a more collaborative and natural way. The idea of softlock is refined into three different kinds of softlocks and the roles of collaborators are taken into account in the proposal of the new scheme. Although these softlocks are illustrated together with read/write hardlocks in this paper, the use of softlocks can be extended to be exploited with other kinds of hardlocks, for example, of granularity locking.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.809-822
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• 2004

In this paper, we propose a concurrency control algorithm based on R-tree for spatial database management system. The previous proposed algorithms can't prevent problem that search operation is to be blocking during update operations. In case of multidimensional indexes like R-tree, locking of update operations may be locked to several nodes, and splitting of nodes have to lock a splitting node for a long time. Therefore search operations have to waiting a long time until update operations unlock. In this paper we propose new algorithms for lock-free search operation. First, we develop a new technique using a linked-list technique on the node. The linked-list enable lock-free search when search operations search a node. Next, we propose a new technique using a version technique. The version technique enable lock-free search on the node that update operations is to be splitting.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.1
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• pp.15-28
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• 1999

In Multilevel Secure Database Management System(MLS/DBMS), we assume that system has a security clearance level for each user and a classification level for each data item in system and the objective of these systems is to protect secure information from unauthorized user. Many algorithms which have been researched have focus on removing covert channel by modifying conventional lock-based algorithm or timestamp-based algorithm. but there is high-level starvation problem that high level transaction is aborted by low level transaction repeatedly. In order to solve this problem, we propose an algorithm to reduce high-level starvation using dynamic adjustment of serialization order, which is basically using orange lock. Because our algorithm is based on a single version unlike conventional secure algorithms which are performed on multiversion, it can get high degree of concurrency control. we also show that it guarantees the serializability of concurrent execution, and satisfies secure properties of MLS/DBMS.

• Journal of Korean Society for Quality Management
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• v.27 no.2
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• pp.251-262
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• 1999

In the automated manufacturing systems, the problem regarding how to make production activities flexible is even more important and critical than that regarding how to product large quantities, and the more flexible, if possible, the manufacturing system is, the more competitiveness and profitable factors it gets. This research, therefore, concentrated on establishing the flexibility and evaluating performance on the manufacturing system, operational flexibility is considered because of enabling the manufacturing system to get both the improvement of production rate and the adaptive ability of environment changes. For it, we used the analytical tool, GSPNs, which is a kind of timed Petri-Nets. GSPNs is competent enough to consider practical situations just like operation priorities, machine failure, randomness, concurrency and so on. Through the GSPNs analysis, it is confirmed that in the manufacturing system with operational flexibility is compatible with the traditional performances such as production rate or mean waiting time.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.735-738
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• 2000

The most important issue in database security is correct concurrency control under the restrictive security policy. The goal of secure transaction management is to keep security and provide many concurrent users with the high availability of database. In this paper, we consider the security environment of multidatabase system with replicated data. The read-from relationship in the existed serializability is improper in security environment. So, we define new read-from relationship and propose new secure 1-copy quasi-seriailzability by utilizing this relationship and display some examples. This security environment requires both the existed local autonomy and the security autonomy as newly defined restriction. To solve covert channel problem is the most difficult issue in developing secure scheduling scheme. The proposed secure 1-copy quasi-serializability is very proper for global transactions in that this serializability not violates security autonomy and prevents covert channel between global transactions.