• Journal of the Korea Society of Computer and Information
• /
• v.24 no.7
• /
• pp.79-85
• /
• 2019

We investigate the D2D utility maximization in the cellular system. We focus on the non cooperative game theoretic approach to maximize the individual utility. Cellular system's perspective, interference from the D2D links must be limited to protect the cellular users. To accommodate this interference issue, utility function is first defined to control the individual D2D user's transmit power. More specifically, utility function includes the pricing which limits the individual D2D user's transmit power. Then, non cooperative power game is formulated to maximize the individual utility. Distributed algorithm is proposed to maximize the individual utility, while limiting the interference. Convergence of the proposed distributed algorithm is verified through computer simulation. Also the effect of pricing factor to SIR and interference is provided to show the performance of the proposed distributed algorithm.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.17 no.2
• /
• pp.115-121
• /
• 2022

This paper proposes a distributed model predictive formation control algorithm for a group of unmanned ground vehicles (UGVs) with guaranteeing collision avoidance between UGVs. Generally, the model predictive control based formation control has a disadvantage in that it takes a long time to compute control inputs when considering collision avoidance between UGVs. In this paper, in order to overcome this problem, the formation control algorithm is implemented in a distributed manner so that it could be individually controlled. Also, a collision-avoidance method considering real-time is proposed. The proposed formation control algorithm is implemented based on robot operating system (ROS), open source-based middleware. Through the various simulation tests, it is confirmed that the formation control of five UGVs is successfully performed while avoiding collisions between UGVs.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.10
• /
• pp.561-572
• /
• 2002

Deadlock detection in distributed systems is considered difficult since no single site knows the exact information on the whole system state. This paper proposes a time-efficient algorithm for distributed deadlock detection and resolution. The initiator of the algorithm propagates a deadlock detection message and builds a reduced wait-for graph from the information carried by the replies. The time required for deadlock detection is reduced to half of that of the other algorithms. Moreover, any deadlock reachable from the initiator is detected whereas most previous algorithms only find out whether the initiator is involved in deadlock. This feature accelerates the detection of deadlock. Resolution of the detected deadlock is also simplified and precisely specified, while the current algorithms either present no resolution scheme or simply abort the initiator of the algorithm upon detecting deadlock.

• Journal of KIISE:Computer Systems and Theory
• /
• v.28 no.9
• /
• pp.469-478
• /
• 2001

It is difficult to test a distributed system because of the task of controlling concurrent events,. Existing works do not propose the test sequence generation algorithm in a formal way and the amount of message is large due to synchronization. In this paper, we propose a formal test sequence generation algorithm using logical clock to control concurrent events. It can solve the control-observation problem and makes the test results reproducible. It also provides a generic solution such that the algorithm can be used for any possible communication paradigm. In distributed test, the number of channels among the testers increases non-linearly with the number of distributed objects. We propose a new remote test architecture for solving this problem. SDL Tool is used to verify the correctness of the proposed algorithm and it is applied to the message exchange for the establishment of Q.2971 point-to-multipoint call/connection as a case study.

• The Journal of Bigdata
• /
• v.7 no.1
• /
• pp.1-14
• /
• 2022

The proof-of-work consensus algorithm used by most blockchains is causing a massive waste of computing resources in the form of mining. A useful proof-of-work consensus algorithm has been studied to reduce the waste of computing resources in proof-of-work, but there are still resource waste and mining centralization problems when creating blocks. In this paper, the problem of resource waste in block generation was solved by replacing the relatively inefficient computation process for block generation with distributed artificial intelligence model learning. In addition, by providing fair rewards to nodes participating in the learning process, nodes with weak computing power were motivated to participate, and performance similar to the existing centralized AI learning method was maintained. To show the validity of the proposed methodology, we implemented a blockchain network capable of distributed AI learning and experimented with reward distribution through resource verification, and compared the results of the existing centralized learning method and the blockchain distributed AI learning method. In addition, as a future study, the thesis was concluded by suggesting problems and development directions that may occur when expanding the blockchain main network and artificial intelligence model.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.4
• /
• pp.1386-1396
• /
• 2017

In this paper, a new approach is proposed to select the optimal sitting and sizing of distributed solar photovoltaic generation (SPVG) in a radial electrical distribution systems (EDS) considering load/generation uncertainties. Here, distributed generations (DGs) allocation problem is modeled as optimization problem with network loss based objective function under various equality and inequality constrains in an uncertain environment. A boundary power flow is utilized to address the uncertainties in load/generation forecasts. This approach facilitates the consideration of random uncertainties in forecast having no statistical history. Uncertain solar irradiance is modeled by beta distribution function (BDF). The resulted optimization problem is solved by a new Dynamic Harmony Search Algorithm (DHSA). Dynamic band width (DBW) based DHSA is proposed to enhance the search space and dynamically adjust the exploitation near the optimal solution. Proposed approach is demonstrated for two standard IEEE radial distribution systems under different scenarios.

• Journal of Multimedia Information System
• /
• v.2 no.1
• /
• pp.143-152
• /
• 2015

Multimedia services in the cloud have become a popular trend in the big data environment. However, how to efficiently schedule a large number of multimedia services in the cloud is still an open and challengeable problem. Current cloud-based scheduling algorithms exist the following problems: 1) the content of the multimedia is ignored, and 2) the cloud platform is a known parameter, which makes current solutions are difficult to utilize practically. To resolve the above issues completely, in this work, we propose a novel distributed multimedia scheduling to satisfy the objectives: 1) Develop a general cloud-based multimedia scheduling model which is able to apply to different multimedia applications and service platforms; 2) Design a distributed scheduling algorithm in which each user makes a decision based on its local information without knowing the others' information; 3) The computational complexity of the proposed scheduling algorithm is low and it is asymptotically optimal in any case. Numerous simulations have demonstrated that the proposed scheduling can work well in all the cloud service environments.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.181-183
• /
• 2005

The existing distribution networks are growing with an increase of power demand more and more. Therefore, for efficient operation of distribution networks, operators are much in need of distributed generation. This paper describes a development of the digital protection relay(HIMAP) for protecting distributed generation which is expected to play an increasing role in electric power systems in the near future. This paper particularly introduces frequency protective algorithm and reverse power protective algorithm among the relaying algorithms for protecting distributed generation in distribution networks and resents capability of a developed digital protection relay including these algorithms.

• Journal of the Korea Safety Management & Science
• /
• v.3 no.3
• /
• pp.191-200
• /
• 2001

Parallel Genetic Algorithms partition the whole population into several sub-populations and search the optimal solution by exchanging the information each others periodically. Distributed Genetic Algorithm, one of Parallel Genetic Algorithms, divides a large population into several sub-populations and executes the traditional Genetic Algorithm on each sub-population independently. And periodically promising individuals selected from sub-populations are migrated by following the migration interval and migration rate to different sub-populations. In this paper, for the Travelling Salesman Problems, we analyze and compare with Distributed Genetic Algorithms using different Genetic Algorithms and using same Genetic Algorithms on each separated sub-population The simulation result shows that using different Genetic Algorithms obtains better results than using same Genetic Algorithms in Distributed Genetic Algorithms. This results look like the property of rapidly searching the approximated optima and keeping the variety of solution make interaction in different Genetic Algorithms.

• ETRI Journal
• /
• v.28 no.1
• /
• pp.31-44
• /
• 2006

In a packet switching network, congestion is unavoidable and affects the quality of real-time traffic with such problems as delay and packet loss. Packet fair queuing (PFQ) algorithms are well-known solutions for quality-of-service (QoS) guarantee by packet scheduling. Our approach is different from previous algorithms in that it uses hardware time achieved by sampling a counter triggered by a periodic clock signal. This clock signal can be provided to all the modules of a routing system to get synchronization. In this architecture, a variant of the PFQ algorithm, called digitized delay queuing (DDQ), can be distributed on many line interface modules. We derive the delay bounds in a single processor system and in a distributed architecture. The definition of traffic contribution improves the simplicity of the mathematical models. The effect of different time between modules in a distributed architecture is the key idea for understanding the delay behavior of a routing system. The number of bins required for the DDQ algorithm is also derived to make the system configuration clear. The analytical models developed in this paper form the basis of improvement and application to a combined input and output queuing (CIOQ) router architecture for a higher speed QoS network.