• International Journal of Computer Science & Network Security
• /
• 제21권4호
• /
• pp.19-27
• /
• 2021

Tasks scheduling have been gaining attention in both industry and research. The scheduling that ensures independent task execution is critical in real-time systems. While task scheduling has gained a lot of attention in recent years, there have been few works that have been implemented into real-time architecture. The efficiency of the classical scheduling strategy in real-time systems, in particular, is still understudied. To reduce total waiting time, we apply three scheduling approaches in this paper: First In/First Out (FIFO), Shortest Execution Time (SET), and Shortest-Longest Execution Time (SLET). Experimental results have demonstrated the efficacy of the SLET in comparison with the others in most cases in a wide range of configurations.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 1998년도 추계종합학술대회 논문집
• /
• pp.127-130
• /
• 1998

Wireless multimedia networks require channel allocation strategies for various multimedia traffic since the mobility of users needs to be considered in addition to diversity of QoS requirements of multimedia traffic. In this paper, we propose an Efficient Channel Allocation strategy, based on prioritization of handoff calls used in Guard channel method. Gurad channels can be shared between non real time calls and real time handoff calls. To decrease the probability of handoff failure, when resources become scarce, the Call Admission Control can take some resources away from the active calls. It is shown through extensive simulations that the proposed strategy provides higher channel utilization and lower probability of handoff failure than existing strategies.

• Journal of Power Electronics
• /
• 제12권5호
• /
• pp.821-829
• /
• 2012

This research article presents a novel approach based on an instantaneous active and reactive power component (p-q) theory for generating reference currents for shunt active filter (SHAF). Three-phase reference current waveforms generated by proposed scheme are tracked by the three-phase voltage source converter in a hysteresis band control scheme. The performance of the SHAF using the p-q control strategy has been evaluated under various source conditions. The performance of the proposed control strategy has been evaluated in terms of harmonic mitigation and DC link voltage regulation. In order to maintain DC link voltage constant and to generate the compensating reference currents, we have developed Fuzzy logic controller with different (Trapezoidal, Triangular and Gaussian) fuzzy M.F.s. The proposed SHAF with different fuzzy M.F.s is able to eliminate the uncertainty in the system and SHAF gains outstanding compensation abilities. The detailed simulation results using MATLAB/SIMULINK software are presented to support the feasibility of proposed control strategy. To validate the proposed approach, the system is also implemented on a real time digital simulator and adequate results are reported for its verifications.

• 한국융합학회논문지
• /
• 제12권9호
• /
• pp.215-227
• /
• 2021

본 연구의 목적은 실시간 비대면 유아체육의 효율적 운영방안을 제시하기 위함이다. 연구 방법은 질적 연구방법 중 심층면담, 비 참여관찰을 통해 자료를 수집하였다. 귀납적 범주분석을 통해 주제어를 도출하였고 Spradley의 영역분석과 분류분석을 통해 분류하였다. 범주화 된 연구 결과는 다음과 같다. 첫째, 실시간 비대면 유아체육 수업에서 고려할 요인의 하위주제로 '수업을 진행하는 장소', '의사소통의 어려움', '비대면에 적합한 프로그램', '시설 및 장비의 중요성'이 나타났다. 둘째, 실시간 비대면 유아체육 수업의 효율적 운영방안의 하위주제로 '비대면 환경을 고려한 수업설계', '확실한 수업 준비', '원격 관리자의 역할', '포스트 코로나에 대비한 지도자 역량강화'가 나타났다. 향후 비대면 유아체육에 대한 연구가 더 필요하며 본 연구를 통해 비대면 유아체육 수업의 효율적 운영방안이 마련되기를 기대한다.

• Journal of Information Technology Applications and Management
• /
• 제14권3호
• /
• pp.227-236
• /
• 2007

Students in cyber universities can take every course because there are no physical constraints such as class rooms. On the other hand. cyber universities should take a heavy burden to schedule real-time exams in a designated time period. Any two courses a student takes must not be simultaneously allocated to a time slot in such a schedule. It is well known that the complexity of this kind of scheduling problem increases exponentially as the number of courses does. This research provides a heuristic method to make on-line real-time exam timetables with minimal exam time span. It considers the constraint of not allocating courses a student takes to simultaneous exam time and prioritizes courses by the number of students.

• 대한전기학회논문지:전력기술부문A
• /
• 제53권11호
• /
• pp.596-603
• /
• 2004

This paper proposes an expert system based on the pattern recognition method which can enhance the accuracy and effectiveness of real-time bus reconfiguration strategy for the transfer of faulted load when a main transformer fault occurs in the automated substation. The minimum distance classification method is adopted as the pattern recognition method of expert system. The training pattern set is designed MTr by MTr to minimize the searching time for target load pattern which is similar to the real-time load pattern. But the control pattern set, which is required to determine the corresponding bus reconfiguration strategy to these trained load pattern set is designed as one table by considering the efficiency of knowledge base design because its size is small. The training load pattern generator based on load level and the training load pattern generator based on load profile are designed, which are can reduce the size of each training pattern set from max L/sup (m+f)/ to the size of effective level. Here, L is the number of load level, m and f are the number of main transformers and the number of feeders. The one reduces the number of trained load pattern by setting the sawmiller patterns to a same pattern, the other reduces by considering only load pattern while the given period. And control pattern generator based on exhaustive search method with breadth-limit is designed, which generates the corresponding bus reconfiguration strategy to these trained load pattern set. The inference engine of the expert system and the substation database and knowledge base is implemented in MFC function of Visual C++ Finally, the performance and effectiveness of the proposed expert system is verified by comparing the best-first search solution and pattern recognition solution based on diversity event simulations for typical distribution substation.

• 한국통신학회논문지
• /
• 제21권2호
• /
• pp.541-551
• /
• 1996

본 연구에서는 인공 신경 회로망을 이용하여 LCD 변수들의 값을 동적으로 변화시킴으로써 보다 개선된 전압 적정유지율을 얻을 수 있는 실시간 ULTC 제어전략이 개발된다. 제안된 전략에서는 수전전압의 변화에 따른 주변압기 송출전압 변화를 인식하는 ANNs, 그리고 ANNs로부터의 전압레벨과 배전선로들의 시간대별 변화패턴을 인식하여, ULTC의 정정치를 동적으로 결정하는 ANNg를 도입함으로서 보다 개선된 전압보상능력을 얻을 수 있도록 하였다. 개발된 제어전략의 성능을 평가하기 위해서 8개의 피더로 구성되는 시험 배전계통에 대해서 부하가 불규칙적으로 변화하였을때, 그리고 부하가 일정한 시간대별 패턴으로 변화하였을때의 ULTC의 전압 보상 전략이 모의된다. 인공 신경회로망은 Fortran 언어로 구현되며 시험계통에 대한 성능평가에서 유용한 결과를 입증하였다.

• 한국멀티미디어학회논문지
• /
• 제12권12호
• /
• pp.1761-1768
• /
• 2009

In this paper, we implemented online real time strategy game using hand as the mouse in augmented reality. Also, we introduced the algorithm for detecting hand direction, finding fingertip of the index finger and counting the number of fingers for interaction between users and the virtual objects. The proposed method increases the reality of the game by combining the real world and the virtual objects. Retinex algorithm is used to remove the effect of illumination change. The implementation of the virtual reality in the online environment enables to extend the applicability of the proposed method to the areas such as online education, remote medical treatment, and mobile interactive games.

• 제어로봇시스템학회논문지
• /
• 제8권7호
• /
• pp.584-588
• /
• 2002

The real-time characteristic of the adaptive leaning control algorithms is validated based on the applied results of the hydraulic servo system that has very strong a non-linearity. The evolutionary strategy automatically adjusts the search regions with natural competition among many individuals. The error that is generated from the dynamic system is applied to the mutation equation. Competitive individuals are reduced with automatic adjustments of the search region in accordance with the error. In this paper, the individual parents and offspring can be reduced in order to apply evolutionary algorithms in real-time. The feasibility of the newly proposed algorithm was demonstrated through the real-time test.

• 제어로봇시스템학회논문지
• /
• 제14권4호
• /
• pp.376-380
• /
• 2008

This paper deals with a performance analysis of real-time control systems, which engages DMR(dual modular redundancy) to detect transient errors and checkpointing technique to tolerate transient errors. Transient errors are caused by transient faults and the most significant type of errors in reliable computer systems. Transient faults are assumed to occur according to a Poisson process and to be detected by a dual modular redundant structure. In addition, an equidistant checkpointing strategy is considered. The probability of the successful task completion in a real-time control system where periodic checkpointing operations are performed during the execution of a real-time control task is derived. Numerical examples show how checkpoiniting scheme influences the probability of task completion. In addition, the result of the analysis is compared with the simulation result.