• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.131-136
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• 2003

Comparison criteria and a selection model for concurrency control algorithms has been presented in this article. In addition, a comparison analysis has been performed with the developed comparison model. The result of the analysis can be utilized to select the best fitting concurrency control algorithm to the user's existing system environment.

• Journal of KIISE
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• v.43 no.9
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• pp.1015-1025
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• 2016

Currently, software testing is becoming increasingly important in the industrial field and a large body of research supports the improvement of efficient software testing. Model-based testing is generally used to formalize user requirement data for test design. Complex system that includes loop and concurrency has a high probability of path explosion problem. Specially, as threads are added to concurrency, test scenarios have also increased exponentially. However, it is difficult to solve this problem using existing techniques. In this paper, we propose novel path-search technique that focuses on behavioral features of concurrency path in order to avoid path explosion problem. A system that contains concurrent paths is represented by activity diagram in case study section. Efficiency of our study is shown through comparison with several generated test scenarios of other studies. The result indicate that our approach is efficient for finding faults in loop and concurrency with fewer test scenario.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2751-2762
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• 1998

In this paper, a new priority assignment ploicy and concurrency control for improvement of transaction predictability and performance are proposed. We present a new priority assignment algorithm called classified priority assignment(CPA), which solves the defects of Earliest Deadline First(EDF) by using class and bucket, and deals with real-time transaction and time-sharing transaction effectively. Also, we present a new concurrency control policy called conditional optimistic concurrency control using lock. It uses optimistic concurrency control for improvement of predictability, and solves transaction conflict by considering priority and execution time of transaction to waste less system resource.

• The KIPS Transactions:PartD
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• v.10D no.3
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• pp.439-446
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• 2003

A crucial limitation in environments where data is broadcast to very large client populations is the low bandwidth available for clients to communicate with servers. Many advanced applications are developed in mobile computing environments, but conventional concurrency controls are not suitable because of the low bandwidth of wireless network. In this paper, we propose a new optimistic concurrency control protocol for mobile transactions. In this protocol, mobile read-only transactions can be completed locally at the clients without additional communication, only mobile update transactions are sent to the server for global validation. Our protocol reduces unnecessary aborts occurred in the previous study using only conflict information. In addition to, our algorithm can detect and resolve non-serializable execution using by data table maintained in a server.

• International journal of advanced smart convergence
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• v.5 no.3
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• pp.32-39
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• 2016

With the help of a small wearable device, patients reside in an isolated village need constant monitoring which may increase access to care and decrease healthcare delivery cost. As the number of patients' requests increases in simultaneously manner, the web service gateway located in the village hall encounters limitations for performing them successfully and concurrently. The gateway based RESTful technology responsible for handling patients' requests attests an internet latency in case a large number of them submit toward the gateway increases. In this paper, we propose the design tasks of the web service gateway for handling concurrency events. In the procedure of designing tasks, concurrency is best understood by employing multiple levels of abstraction. The way that is eminently to accomplish concurrency is to build an object-oriented environment with support for messages passing between concurrent objects. We also investigate the performance of event-driven architecture for building web service gateway using node.js. The experiments results show that server-side JavaScript with Node.js and MongoDB as database is 40% faster than Apache Sling. With Node.js developers can build a high-performance, asynchronous, event-driven healthcare hub server to handle an increasing number of concurrent connections for Remote Healthcare Monitoring System in an isolated village with no access to local medical care.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.10
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• pp.2301-2306
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• 2015

The time to address the exabytes of data has come as the information age accelerates. Big data transfer technology is essential for processing large amounts of data. This paper posits to transfer big data in the optimal conditions by the proposed algorithm for predicting the optimal combination of Pipelining, Concurrency, and Parallelism (PCP), which are major functions of GridFTP. In addition, the author introduced a simple design process of Takagi-Sugeno-Kang (TSK) fuzzy model and designed a model for predicting transfer throughput with optimal combination of Pipelining, Concurrency and Parallelism. Hence, the author evaluated the model of the proposed algorithm and the TSK model to prove the superiority.

• Journal of the Korea Society of Computer and Information
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• v.1 no.1
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• pp.147-158
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• 1996

This paper proposed a concurrency control structure based on specialized data flow graphs that was analysed a run-time concurrency control activity to be integrated with the task scheduler Data were viewed as flowing on the arcs from one node to another in a stream of discrete to tokens. The network that Is based upon the Entity-Relationship model, can be viewed a fixed problems used query tokens as a data flow graph. The performance was measured used in the various expriments compared the overall performance of the different concurrency control methods, DBFG (DataBase Flow graphs) scheduling had the knowledge to obtain better performance than 2PL in a distributed environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.430-433
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• 2017

Programming that ensures concurrency is essential for developers. If you do not use it, it is hard to expect the speed of the program to improve unless there is technical advancement of the hardware itself. Programming languages that support good concurrency code include go, elixir, and scala. Python, which supports a number of useful libraries, also supports concurrent programming like asyncio and coroutine. This paper defines the concepts of concurrency and parallelism, and explains what to note when writing concurrency programming in Python. The crawler that collects web data is written in concurrent code and compared with programs written in sequential, multithreaded code.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.633-639
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• 2004

The performance of optimistic concurrency control schemes which are generally used for Mobile computing is very sensitive to the transaction abort rate. Even if the abort probability can be reduced by back-shifting the timestamp from the time of requesting a commit, some transactions continuously perform unnecessary operations after the transactions accessed write-write conflicting data. In this paper, we propose an optimistic protocol that can abort the transactions during the execution phase by using the write notification approach. The proposed protocol enhances the performance of the optimistic concurrency control by reducing the unnecessary operations. In addition, we present a simulation study that compares our schemes with the timestamp based certification scheme. This study shows that our scheme outperforms the timestamp based certification scheme.

• 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.