• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.37 no.1
• /
• pp.96-103
• /
• 2014

A steady-state controllable M/G/1 queueing model operating under the (TN) policy is considered where the (TN) policy is defined as the next busy period will be initiated either after T time units elapsed from the end of the previous busy period if at least one customer arrives at the system during that time period, or the time instant when Nth customer arrives at the system after T time units elapsed without customers' arrivals during that time period. After deriving the necessary system characteristics such as the expected number of customers in the system, the expected length of busy period and so on, the total expected cost function per unit time in the system operation is constructed to determine the optimal operating policy. To do so, the cost elements associated with such system characteristics including the customers' waiting cost in the system and the server's removal and activating cost are defined. Then, the optimal values of the decision variables included in the operating policies are determined by minimizing the total expected cost function per unit time to operate the system under consideration.

• Journal of Advanced Navigation Technology
• /
• v.18 no.5
• /
• pp.501-507
• /
• 2014

A dynamic system is called positive if any trajectory of the system starting from non-negative initial states remains forever non-negative for non-negative controls. In this paper, new sufficient conditions for asymptotic stability of the interval positive time-varying linear discrete-time systems with time-varying delay in states are considered. The considered time-varying delay time has an interval-like bound which has minimum and maximum delay time. The proposed conditions are established by using a solution bound of the Lyapunov equation and they are expressed by simple inequalities which do not require any complex numerical algorithms. An example is given to illustrate that the new conditions are simple and effective in checking stability for interval positive time-varying discrete systems.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.1 no.2
• /
• pp.90-103
• /
• 2006

There are many file systems in various operating systems. Those are usually designed for server environments, where the common cases are usually 'multiple active users', 'great many small files' And they assume a big main memory to be used as buffer cache. So the existing file systems are not suitable for resource hungry embedded systems that process multimedia data streams. In this study, we designed and implemented a new file system which efficiently stores and retrieves multimedia data steams. The proposed file system has a very simple disk layout, which guarantees a quick disk initialization and file system recovery. And we introduced a new indexing-scheme, called the time-based indexing scheme, with the file system. With the indexing scheme, the file system maintains the relation between time and the location for all the multimedia streams. The scheme is useful in searching and playing the compressed multimedia streams by locating exact frame position with given time, resulting in reduction of CPU processing and power consumption. The proposed file system and its APIs utilizing the time-based indexing schemes were implemented firstly on a Linux environment, though it is operating system independent. In the performance evaluation on a real DVR system, which measured the execution time of multi-threaded reading and writing, we found the proposed file system is maximum 38.7% faster than EXT2 file system.

• International Journal of Computer Science & Network Security
• /
• v.21 no.3
• /
• pp.153-164
• /
• 2021

The increasing importance of such fields as embedded systems, pervasive computing, and hybrid systems control is increasing attention to the time-dependent aspects of system modeling. In this paper, we focus on modeling conceptual time. Conceptual time is time represented in conceptual modeling, where the notion of time does not always play a major role. Time modeling in computing is far from exhibiting a unified and comprehensive framework, and is often handled in an ad hoc manner. This paper contributes to the establishment of a broader understanding of time in conceptual modeling based on a software and system engineering model denoted thinging machine (TM). TM modeling is founded on a one-category ontology called a thimac (thing/machine) that is used to elaborate the design and analysis of ontological presumptions. The issue under study is a sample of abstract modeling domains as exemplified by time. The goal is to provide better understanding of the TM model by supplementing it with a conceptualization of time aspects. The results reveal new characteristics of time and related notions such as space, events, and system behavior.

• Quality Improvement in Health Care
• /
• v.3 no.1
• /
• pp.144-152
• /
• 1996

Background : Because of introduction of nationwide health care system in 1989 and the improvement of socioeconomic status of population the number of outpatient visiting university hospital has good facilities and manpower has increased. So the waiting time for medical service at university hospital are lengthened. Particularly outpatients complain that waiting for prescribed drugs at pharmacy depart are long. Reducing waiting time at pharmacy depart door-to-door delivery system that the patients applying for door-to-door delivery receive prescribed drug at home without waiting at pharmacy depart were studied. The objective of this study is to analysis the opinion of outpatients for door-to-door delivery system, to study the appropriateness of adopting the system and to produce ideal model for the system. Method : Outpatients waiting drug at pharmacy depart were questioned about door-to-door delivery system. to find the factors affect utilizing the system the logistic regression was used. Result : 83.3% of the patients want to utilize the system without charging, and 72.9% of the patients want to utilized system with charging. 68.3% of patients with charging want to use this system because of long waiting time at pharmacy depart. 50% of patients who do not want to use door-to-door do not use this system because of incorrect delivery. The affecting factors to utilize the system were sex, waiting time, fee. Conclusion : The model for door to door delivery system. 1. door-to-door personnel reside in hospital and the patient want to utilize the system apply for the delivery with charging. 2. The applied drugs dispense at spare time. 3. Delivery company gathers drug at appointed time and delivers. 4. The delivery fee is 2,000-3,000 won. 5. To prevent from loss and changing the drug the name of patient on packet are printed and drug packet are sealed. 6. The company submit the confirm sheet which are written that the patient received drug correctly to hospital. 7. The delivery time of drug is reserved for the convenience of receiving.

• Convergence Security Journal
• /
• v.8 no.1
• /
• pp.43-48
• /
• 2008

Previously, we need to log-in to the target system to check the system log. This is a problem that can not be monitored in real time. This paper designed a syslog real-time monitoring system to solve this problem. The proposed system be able to detect a problem of system in real time without log-in process and be able to solve problems immediately. The proposed syslog real-time monitoring system in this paper is based on Windows OS.

• IE interfaces
• /
• v.20 no.4
• /
• pp.547-559
• /
• 2007

In this paper, we design Real-Time Postal Logistics Operational Model and System as a to-be system. Current postal logistics information system, named PostNet, is a basic infra system designed for an end-to-end IT-driven process, from mail acceptance to delivery, linked with internal and external systems. Recent competing circumstances drive demand for more intelligent information system. So we design real-time postal logistics operational system focused on site operations. we analyze postal logistics operation and interview field workers and establish real-time postal logistics operational model to solve operational issues. Finally we suggest system specifications.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.1
• /
• pp.194-203
• /
• 2005

The process of guaranteeing that a distributed real-time control system will meet its timing constraints, is referred to as schedulability analysis. However, schedulability analysis algorithm cannot be simply used to analyze the system because of complex calculations of algorithm. It is difficult for control engineer to understand the algorithm because it was developed in a software engineer's position. In this paper we introduce a Response-time Analysis Tool(RAT) which provides easy way far system designer to analyze the system by encapsulating calculation complexity. Based on the RAT, control engineer can verify whether all real-time tasks and messages in a system will be completed by their deadline in the system design phase.

• Proceedings of the KIEE Conference
• /
• 2004.11c
• /
• pp.72-75
• /
• 2004

In this paper, the task assignment strategy considering communication delay and the priority of distributed tasks is proposed for the real-time network system in order to maximize the utilization of the system. For the task assignment strategy, the relationship among priority of tasks in network nodes, the calculation time of each task, and the end-to-end response time including the network delay is formulated firstly. Then, the task assignment strategy using the genetic algorithm is proposed to optimize the utilization of the system considering the LCM(Least Common Multiple) period. The effectiveness of proposed strategy is proven by the simulation for estimating the performance such as the utilization and the response time of the system in case of changing the number of tasks and the number of network nodes.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.33B no.12
• /
• pp.13-23
• /
• 1996

In tis paper we researched the implementation methodology and techniques for the high real-time responsive operating system of an ISDN PABX system. The operating system we developed takes a high role as a dedicated real-time operating system for PABX systems. It provides the functions and synchronization, interprocessor communication, interrupt processing, and data I/O processing. And also it provides lots of real-time processing functions for supproting various real-time applications. Finally, we evaluated the performance by measuring the best, the average, and the worst-case execution time of all functions implemented in this real-time operating system.