• Journal of KIISE:Computer Systems and Theory
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• v.34 no.8
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• pp.367-376
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• 2007

In this paper, we introduce an application-specific and adaptive power management technique for portable systems that support dynamic voltage scaling (DVS). We exploit both the idle time of multitasking systems running soft real-time tasks as well as memory- or CPU-bound code regions. Detailed power and execution time profiles guide an adaptive power manager (APM) that is linked to the operating system. A post-pass optimizer marks candidate regions for DVS by inserting calls to the APM. At runtime, the APM monitors the CPU's performance counters to dynamically determine the affinity of the each marked region. for each region, the APM computes the optimal voltage and frequency setting in terms of energy consumption and switches the CPU to that setting during the execution of the region. Idle time is exploited by monitoring system idle time and switching to the energy-wise most economical setting without prolonging execution. We show that our method is most effective for periodic workloads such as video or audio decoding. We have implemented our method in a multitasking operating system (Microsoft Windows CE) running on an Intel XScale-processor. We achieved up to 9% of total system power savings over the standard power management policy that puts the CPU in a low Power mode during idle periods.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.81-90
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• 2016

Different from general operating policies to be applied for controllable queueing models, two of three well-known simple N, T and D operating policies are applied alternatingly to the single server controllable queueing models, so called alternating (NT), (ND) and (TD) policies. For example, the alternating (ND) operating policy is defined as the busy period is initiated by the simple N operating policy first, then the next busy period is initiated by the simple D operating policy and repeats the same sequence after that continuously. Because of newly designed operating policies, important system characteristic such as the expected busy and idle periods, the expected busy cycle, the expected number of customers in the system and so on should be redefined. That is, the expected busy and idle periods are redefined as the sum of the corresponding expected busy periods and idle periods initiated by both one of the two simple operating policies and the remaining simple operating policy, respectively. The expected number of customers in the system is represented by the weighted or pooled average of both expected number of customers in the system when the predetermined two simple operating policies are applied in sequence repeatedly. In particular, the expected number of customers in the system could be used to derive the expected waiting time in the queue or system by applying the famous Little's formulas. Most of such system characteristics derived would play important roles to construct the total cost functions per unit time for determination of the optimal operating policies by defining appropriate cost elements to operate the desired queueing systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.7
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• pp.1026-1031
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• 2022

Cognitive Radio Ad-Hoc Networks (CRAHNs) enable to overcome the shortage of frequency resources due to the increase of radio services. In order to avoid interference with the primary user in CRANH, channel sensing to check the idle channel is required, and when the primary user appears, the time delay due to handover should be minimized through fast idle channel selection. In this paper, throughput was improved by reducing the number of channel sensing and preferentially sensing a channel with a high probability of being idle, using reinforcement learning. In addition, we proposed a multi-channel MAC (Medium Access Control) protocol that can minimize the possibility of collision with the primary user by sensing the channel at the time of data transmission without performing periodic sensing. The performance was compared and analyzed through computer simulation.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.23-26
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• 2002

In this paper, we modelize several scheduling algorithms for real-time packet filtering tasks based on the multi-threaded multi-processor architecture for the network security system like the firewall and compare the performance of the algorithms by implementing the algorithms and doing a number of empirical tasks. As the matrices of the performance we use the idle factor and the packet transfer rate. We get the idle factors and the packet transfer rates according to the transfers of the packet sizes from 64 bytes to 1500 bytes.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.175-181
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• 2014

This paper suggests O(m) polynomial time heuristic algorithm to obtain the solution for the driver scheduling problem, DSP, that has been classified as NP-complete problem. The proposed algorithm gets the initial assignment of n minimum number of drivers from given m schedules. Nextly, this algorithm gets the minimum total time (TC) using 5 rules of swap and insert for decrease of over times (OT) and idle times (IT). Although this algorithm is a heuristic polynomial time algorithm with O(m) time complexity rules to be find a optimal (or approximate) solution, this algorithm is equal to metaheuristic methods for the 5 experimental data. To conclude, this paper shows the DSP is not NP-complete problem but Polynomial time (P)-problem with polynomial time rules.

• Journal of Internet Computing and Services
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• v.6 no.6
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• pp.1-12
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• 2005

The number of web contents is enormous in the billions and rapidly growing, Most contents are state, but an increasing number are generated dynamically, Therefore, Internet-based client/server architecture of Contents Delivery Service System suffers from frequent disconnections and security threats casused by dependency of the server or overload. Idle computing resources in Internet are used for sloving these issues, In this paper, We implement and design the Content Delivery Service System for cyber education system using idle Computing Power in P2P computing to share computing resources, We implement not only internet infrastructure but also satellite infrastructure system. and designed to transfer real-time or non real-time contents.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.247-259
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• 1992

In this paper, the types of the data exchange between a cell site and a cobile phonefor the call processing on the AMPS(Advanced Mobile Phone Service) are investigated, and the circuit for processing the wideband data stream according to the data types is designed and implemented. The circuit for detecting the Busy / Idle bit which is needed for determining the channel access, the circuit for detecting the word sync and the circuit for transmitting and receiving the wideband data is designed. The 3-out-of-5 majority vote of the 5received data is performed to reduce error and an algorithm requiring a small buffer size for real time processing of voting process is proposed. The method to overcome the computational complexity and the real time constraint of the conventional BCH decoding is proposed.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.483-492
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• 2007

In this paper, we propose a new hybrid approach based on query tree protocol to arbitrate tag collisions in RFID systems. The hybrid query tree protocol that combines a tree based query protocol with a slotted backoff mechanism. The proposed protocol decreases the average identification delay by reducing collisions and idle time. To reduce collisions, we use a 4-ary query tree instead of a binary query tree. To reduce idle time, we introduce a slotted backoff mechanism to reduce the number of unnecessary Query commands. Simulation and numerical analysis reveal that the proposed protocol achieves lower identification delay than existing tag collision arbitration protocols.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.10 no.1
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• pp.14-26
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• 2011

In this paper, we've studied Optical Fiber Subscribe Transmit system. After receiving the ATM cell passing through the FIFO of the Asynchronous Transfer Method from the ATM Layer images to the VC4 signal payload passing through scrambling of the cell payload, HEC computation of the cell and inserting the Idle/Unassigned cell. At this time formed VC4 signal passing through the generating and inserting POH overhead at the same time indicating the start point of the cell by the H4 byte on the VC4 POH. This ATM cell transmits 155Mbps speed changing the optical signal after outputting the frame format at the STM-1 signal generation block through the AUG bus after generating J1 of the VC4 start point at the AU4 pointer generation block.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.780-788
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• 2011

The lack of QoS (Quality of Service) support functionalities in IEEE 802.11 DCF mode makes it difficult to provide real-time multimedia services in WLANs. In this paper, we propose an effective available bandwidth measurement method in IEEE 802.11b DCF environments. The proposed method measures the total channel idle time and the collision probability during each measurement period. Then, the available bandwidth is calculated by considering those measured information and the transmission overheads at MAC and PRY layers. The performances of the proposed method are evaluated using OPNET simulator. The simulation results show that the proposed method provides more exact results than existing comparable schemes.