• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.4
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• pp.369-375
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• 2001

This paper proposes a dual real-time scheduling design under real-time constraints kernel environments. In this paper, we have designed both the real-time kernel and the general kernel that have their different properties to satisfy these properties, that is, interrupt latency, scheduling precision, and message passing. In real-time tasks, interrupt processing should be run. In general kernel, non real-time tasks or general tasks are run. Also, when tasks conflict, it executed the mixed priority scheduling that non real-time kernel executed static scheduling and real-time kernel executed dynamic priority transformation scheduling, that is, least-laxity-first/minimization preemption scheduling. We have compared the results of this study for performance of the proposal real-time kernel with both RT Linux 0.5a and QNX 4.23A, that is, of interrupt latency scheduling precision and message passing.

• KIISE Transactions on Computing Practices
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• v.22 no.1
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• pp.1-7
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• 2016

When multiple applications are running concurrently on a multi-processor system, interferences between applications make it difficult to guarantee real-time constraints. We propose a novel interference analysis technique that allows sharing of share processors among dataflow applications, while satisfying real-time constraints. Based on the interference analysis, we develop a co-scheduling technique that aims to minimize the resource usage. Compared to an existent technique that involves converting application graphs to real-time tasks, the proposed technique shows better results in terms of resource usage, especially when it is applied to applications with tight time constraints.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.40-44
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• 2004

A fact that limits a company's ability to achieve more of its goal is referred to as a 'constraint' shipbuilding industries need to identify and manage constraints. The theory of constraints is evolved out of the problems of bottleneck formation. This happens and is conserved for the formulation if various real time problems for arriving standard uniquely addressed problems If, for example, the goal of a shipbuilding industry is to make money now and in the future, it is suggested that TOC will enable th mangers of the company to do so. TOC, focuses the organization scare resources on improving the performance of the true constraints, and therefore the bottom line of the organization. An attempt is made for the implantation of the theory into real world shipyard decision support mechanism.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.609-615
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• 1987

The optimal operation of power system is developed by alternately using real power dispatch and reactive power dispatch problem. The real power system scheduling process is formulated as an optimization problem with linear inequality constraints. A.C. loadflow method is used for the problem solution and line losses are considered. The constraints under consideration are generator power limits, load scehdling limits and line capacity limits. In solving the objective function the Dual Relaxation method is adopted. Tests indicate that the method is practical for real time application. The reactive power control problem uses the Dual Simplex Relaxation method as in the real scheduling case. Insted of minimizing the cost of power system, the objective is selected as to determine the highest possible voltage schedule. The constraints under consideration are the voltage limits at each node and the possibilities of supply or absobtion of reactive energy by generator units and the compensation facilities. Tests indicate that the method is practical for real time applications. The overall optimization methods developed in this paper proved to obtained fine results in minimizing object function compared with the method without using voltage control. And the overall voltage profiles were also improved.

• The KIPS Transactions:PartA
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• v.19A no.2
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• pp.101-112
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• 2012

In recently years, distributed real-time software has performed important roles in various areas. Real-time applications should be performed with satisfying strict constraints on response time. Usually real-time applications are developed on the real-time supporting middleware such as TMO(Time-triggered, Message-triggered Object), CORBA/RT, and RTAI. However, it is not easy to develop applications using them since these real-time middleware are unfamiliar to programmers. In this paper, we propose an automatic code generator for real-time application based on TMO in order to reduce development costs. For increasing or reflecting the characteristics of TMO into the design model, SpM and SvM methods are added into the class diagram, which have time constraints as their properties. And behaviors of them are represented as separated regions on state machine diagram in different abstract level. These diagrams are inputted into TMO-based code automatic generator, which generates details of the TMO class. Our approach has advantages for decreasing effort and time for making real time software by automatically generating TMO codes without detailed knowledge of TMO.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.120.4-120
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• 2001

In this paper, a method of generating trajectories in real time for a mobile robot in a dynamic environment is proposed. Specifically, this method is focused on soccer-playing robots that need to calculate trajectories in real time, which are constantly subject to rapidly change as targets and obstacles move. The robots also should move at the fastest available speed, while tracking the generated trajectories. The method proposed in this paper solves the geometric problem of finding a smooth curve that joins two endpoints. To have this solved, we assign five constraints to each endpoint, which are the usual x, y, theta, and curvature as well as the influence of the initial robot velocity on the path. With these five constraints, the path generated can always be physically followed by robot. Through this method, the travel time of the robot over the entire path can b optimized. Therefore it can ...

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.2
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• pp.127-136
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• 2016

The camera based object detection systems should satisfy the recognition performance as well as real-time constraints. Particularly, in safety-critical systems such as Autonomous Emergency Braking (AEB), the real-time constraints significantly affects the system performance. Recently, multi-core processors and system-on-chip technologies are widely used to accelerate the object detection algorithm by distributing computational loads. However, due to the advanced hardware, the complexity of system architecture is increased even though additional hardwares improve the real-time performance. The increased complexity also cause difficulty in migration of existing algorithms and development of new algorithms. In this paper, to improve real-time performance and design complexity, a task scheduling strategy is proposed for visual object tracking systems. The real-time performance of the vision algorithm is increased by applying pipelining to task scheduling in a multi-core processor. Finally, the proposed task scheduling algorithm is applied to crosswalk detection and tracking system to prove the effectiveness of the proposed strategy.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.534-538
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• 1995

In this paper, a realization of a real-time train information system(TIS) is discussed. The requirements of TIS which satisfy real-time constraints are analyzed in view of data transfer. For efficient data communication in TIS, a new network system is suggested and its real-time characteristics are analyzed and compared with the standard network system. A local unit is designed based on VMEbus system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.43-48
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• 2022

With the recent performance improvement of mobile devices as well as the emergence of various applications, not only interactive tasks but also real-time tasks are rapidly increasing. As real-time tasks have deadline requirements, resource management policies used in the conventional time-sharing systems have limitations in satisfying real-time constraints. In this paper, we examine how to efficiently manage resources while satisfying the constraints of real-time tasks through end-to-end resource management of CPU, memory, and storage when interactive and real-time tasks are executed concurrently on a mobile device. Instead of suggesting complicated resource management policies, we focus on examining the basic concepts necessary for each resource management. Specifically, we first look at basic policies such as assigning dedicated CPU cores for real-time tasks, allocating a certain working set of real-time tasks in memory, and using fast storage without context switch in I/O. We then consider how these basic policies can be adopted efficiently.

• Journal of Internet Computing and Services
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• v.1 no.2
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• pp.11-18
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• 2000

In this paper we present a new extensible model based upon the concept of subtransactions in real-time transaction systems. The nested transaction model originally proposed by J. Moss is extended for real-time uniprocessor transaction systems by adding explicit timing constraints. Based upon the model, an integrated concurrency control and scheduling algorithm is developed, that not only guarantees timing constraints of a set of real-time transactions but also maintains consistency of the database. The algorithm is based on the priority ceiling protocol of Sha et al. We prove that the Real-Time Nested Priority Ceiling Protocol prevents unbounded blocking and deadlock, and maintains the serializability of a set of real-time transactions. We use the upper bound on the duration that a transaction can be blocked to show that it is possible to analyze the schedulability of a transaction set using rate-monotonic priority assignment. This work is viewed as a step toward multiprocessor and distributed real-time nested transaction systems. Also, it is possible to be extended to include the real-time multimedia transactions in the emerging web-based database application areas.