• Journal of Korea Society of Industrial Information Systems
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• v.28 no.4
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• pp.35-43
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• 2023

In next-generation electric vehicles, research is being conducted on an in-wheel motor system that directly controls torque by each wheel to improve total cost and driving performance. Accordingly, in this paper, a study was conducted on an algorithm that distributes the torque applied to each wheel in a torque vectoring system applied to an in-wheel motor for driving an electric vehicle. In order to implement a vehicle model that applies actual vehicle characteristic parameters according to vehicle driving and steering, a simulation was conducted in the MATLAB Simulink environment, and it was confirmed that torque distribution was performed according to the proposed algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1704-1712
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• 2014

The unused Worst-Case Execution Time (WCET) allocated to a real-time task occurs when the actual execution time of the task can be far less than the WCET preassigned to the task for a schedulability test. Any unused WCET allocated to the task can be exploited to reduce the power consumption of battery-powered sensor nodes through real-time power-aware scheduling techniques. From the distribution perspective of the unused WCET, the unused WCET distribution policy is classified into three types: Conservative Unused WCET (CU-WCET), Moderate Unused WCET (MU-WCET), and Aggressive Unused WCET (AU-WCET) distribution policies. We evaluated the performance of real-time power-aware scheduling techniques incorporating each of three unused WCET distribution policies in terms of low power consumption.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.199-208
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• 2009

Recently,IP-based broadcasting systems,such as Mobile-TV and IP-TV, have been widely deployed. These systems require a security system to allow only authorized subscribers access to broadcasting services. We analyzed the Conditional Access System, which is a security system used in the IP-based Pay-TV systems. A weakness of the system is that it does not scale well when the system experiences frequent membership changes. In this paper, we propose a group key distribution protocol which overcomes the scalability problem by reducing communication and computation overheads without loss of security strength. Our experimental results show that computation delay of the proposed protocol is smaller than one of the Conditional Access System. This is attributed to the fact that the proposed protocol replaces expensive encryption and decryption with relatively inexpensive arithmetic operations. In addition, the proposed protocol can help to set up a secure channel between a server and a client with the minimum additional overhead.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.112-121
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• 2010

Distributed video coding is a coding paradigm that allows complexity to be shared between encoder and decoder, in contrast with conventional video coding. We propose that complexity balancing method of encoder/decoder by phase motion estimation algorithm. The encoder performs partial motion estimation. The result of the partial motion estimation is transferred to the decoder, and the decoder performs motion estimation within the narrow range. When the encoder can afford some complexity, complexity balancing is possible. The method proposed is able to know relativity between complexity balancing and coding efficiency. The coding efficiency increase rate by the encoder complexity increases is higher than that by the decoder complexity increases. The proposed method can control the complexity and coding efficiency according to devices' resources and channel conditions.

• KIISE Transactions on Computing Practices
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• v.23 no.9
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• pp.572-577
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• 2017

Virtualization allows multiple virtual machines to share the resources of a physical machine in order to utilize idle resources. The purpose of virtualization is the efficient allocation of resources among virtual machines. However, the efficient allocation of resources is difficult because the workload characteristics of each virtual machine cannot be understood in the current virtualization environment. This causes performance interference among virtual machines, which leads to performance degradation of the virtual machine. Previous works have been carried out to develop a method of solving such performance interference. This paper introduces a representative method, a CPU scheduling method that guarantees I/O performance by using feedback control to solve performance interference. In addition, we compare and analyze a model-based feedback control method and a dynamic feedback control method.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.3
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• pp.60-71
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• 2017

Smart devices such as smart phones, smart TVs, and smart pads have become essential devices in recent years. As the popularity and demand grows, the performance of smart devices is also getting better and users are dealing with a lot of things such as education and business using smart devices instead of desktop. However, smart devices that still have poor performance compared to desktop, even with improved performance, have difficulty running high performance applications due to limited resources. In this paper, we propose a load balancing algorithm applying the characteristics of smart devices to overcome the resource limitations of devices. in order to verify the algorithm, we implemented the algorithm after adding the distributed processing system service in Android platform. After constructing the cluster on the smart device, various experiments were conducted. Through the analysis of the test results, it is confirmed that the proposed algorithm efficiently improves the overall distributed processing performance by effectively aggregating different amounts of computing resources in heterogeneous smart devices.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.93-97
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• 2015

In this Paper, we proposed optimization of system performance, optimal splitting factor applied to power splitting protocol with relay in the cooperative communication undergo co-channel interference. We can possible to optimize and maximize the channel capacity of the receiver through optimal factor of splitting protocol. So, we can solve inability in system, and to increase the efficiency of the network. Finally, performance of the proposed protocol is analyzed in terms of outage probability, capacity of system.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.61-70
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• 2017

Robust thrust distribution method of solid DACS is researched. For the case of the system which has higher number of actuation nozzles than the degree of freedom of thrust to be controlled, the robust thrust allocation law which accommodate the abnormal operation is suggested. Assuming the situation that some nozzles are uncontrollable, the error between nozzle throat area command and response can be calculated. The error is used for realtime reshaping of weighting matrix. From the weighting effect, the nozzle which operated abnormally has low responsibility for the command then, the thrust error is reduced. The suggested algorithm is verified by the simulation of abnormal operation condition of DCS and ACS nozzle respectively.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.3
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• pp.111-119
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• 2008

This paper combines fuzzy concepts with an existing dynamic performance isolation technique in order to improve the response time performance of a Web server supporting differentiated services. A load balancing mechanism based on the fuzzy control technique is developed in such a way that ambiguous situations caused by workload estimation of cluster-based Web servers, client request rates, and dynamic request rates can be represented in an effective way. In addition, we verify that the fuzzy-based performance isolation technique improves the performance and robustness of differentiated service systems efficiently through comparing 95-percentile of response time between the fuzzy-based Performance isolation technique and the existing one, which do not use the fuzzy concept.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.668_669
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• 2009

상업운전이 개시된 이래 24년이 경과한 원자력발전소의 480V 저전압분배계통 차단기의 설비특성, 운전 및 정비경험, 현행 정비활동, 경년열화, 성능, 단종 분야를 검토하여 480V 저전압분배계통 차단기에서 제기될 수 있는 현안사항과 이를 해결하기 위한 일련의 수명관리계획을 도출하는 기술성 평가를 수행하였다. 기술성 평가를 통해 제시된 일련의 수명관리계획안에 대하여 비용 및 고장률 데이터를 근거로 EPRI의 LcmVALUE 프로그램을 이용하여 경제성을 분석하고 480V 저전압분배계통차단기의 최적 수명관리계획과 권고사항을 제시하였다.