• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.2
• /
• pp.322-330
• /
• 1994

SIBs(Service Independent Building block) are defined in CCITT advanced intelligent network concept model for supporting various services in the future. This paper describes the protocol modeling and verification for basic call process SIB. For modeling, we use Petri Net and verify this modeling by analyzing reachability tree of Petri Net. Results of this paper should be used for design and implementation of basic call process SIB.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.12
• /
• pp.82-88
• /
• 2008

This paper describes an application of sliding mode control to an active magnetic bearing(AMB) system. A sliding mode control is robust to model uncertainties and external disturbances. To ensure the authority of sliding mode control, model parameter uncertainties caused from linearization of electro-magnetic attractive force are analyzed and a domain of parameter uncertainties in which reachability to sliding surface is guaranteed is derived. The validity of the analysis is illustrated along with some simulation examples.

• Journal of Institute of Control, Robotics and Systems
• /
• v.14 no.3
• /
• pp.213-220
• /
• 2008

The object of this paper is to propose a method to deal with the problem of modeling user specifications in approaches based on supervisory control and Petri nets. However, most of Petri Net approaches are based on forbidden states specifications, and these specifications are suitable the use of tool such as the reachability graph. But these methods were not able to show the user specification easily and these formalisms are generally limited by the combinatorial explosion that occurs when attempting to model complex systems. Herein, we propose a new efficient method using FSSTP (Forbidden Sequences of State-Transitions Problem) and theory of region. Also, to detect and avoid the deadlock problem in control process, we use DAPN method (Deadlock Avoidance Petri nets) for solving this problem in control model.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.11
• /
• pp.2463-2470
• /
• 2010

In some cases of u-health services, it is important and then required to pursue the location of users in real time because users could occasionally be in the situation beyond self-regulation. Location positioning has used two such typical techniques as trilateration and fingerprinting. A trilateration technique is usually based on three resident coordinates to identify the location of the target node. Ranging that measures distances between coordinates and the node is essential for applying the trilateration technique. Users especially in u-health services could be out of reachability in any such reasons as out of propagation ranges, fault of a communication counterpart, non-existence of possible communication facility, etc. This paper proposes a real-time locating method which can improve to identify and track the location of mobile objects. The method is based on references of identified mobile nodes as well as resident coordinates even though they may be partially out of communication reachability.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.12
• /
• pp.1780-1792
• /
• 2016

In this paper, we propose an efficient counter-based broadcast scheme for high reachability and energy efficiency. To achieve this, we propose a method to calculate additional coverage when a node receives the same broadcast message from both nodes, in order to rebroadcast by a node who can cover an large area. We also propose a formula to determine random access delay (RAD) considering addition coverage, distance, density, and remaining battery information, and a formula to determine count threshold ($C_{th}$) considering density and remaining battery information. In addition, we evaluate the performance of the proposed broadcast scheme compared with the existing counter-based broadcast schemes through simulation.

• The Mathematical Education
• /
• v.57 no.4
• /
• pp.353-369
• /
• 2018

This study started with the following questions. Suppose that students do not accept various forms of geometric series tasks as the same task. Also, let's say that the approach was different for each task. Then, when they realize that they are the same task, how will students connect the different approaches? This study is a process of pro-actively confirming whether or not such a question can be made. For this purpose, three students in the second grade of high school participated in the teaching experiment. The results of this study are as follows. It also confirmed how the students think about the various types of tasks in the geometric series. For example, students have stated that the value is 1 in a series type of task. However, in the case of the 0.999... type of task, the value is expressed as less than 1. At this time, we examined only mathematical expressions of students approaching each task. The problem of reachability was not encountered because the task represented by the series symbol approaches the problem solved by procedural calculation. However, in the 0.999... type of task, a variety of expressions were observed that revealed problems with reachability. The analysis of students' expressions related to geometric series can provide important information for infinite concepts and limit conceptual research. The problems of this study may be discussed through related studies. Perhaps more advanced research may be based on the results of this study. Through these discussions, I expect that the contents of infinity in the school field will not be forced unilaterally because there is no mathematical error, but it will be an opportunity for students to think about the learning method in a natural way.

• Proceedings of the IEEK Conference
• /
• 1999.11a
• /
• pp.384-387
• /
• 1999

In this paper, we have proposed a testing methodology for Speed-Independent asynchronous control circuits using the self-checking property where the circuit detects certain classes of faults during normal operation. To exploit self-checking properties of Speed-Independent circuits, the Proposed methodology generates tests from the specification of the target circuit which describes the behavior of the circuit. The generated tests are applied to a fault-free and a faulty circuit, and target faults can be detected by the comparison of the outputs of the both circuits. For the purpose of efficient comparison, reachability information of the both circuits in the form of BDD's is used and operations are conducted by BDD manipulations. The identification for undetectable faults in testing is also used to increase efficiency of the proposed methodology. The proposed identification uses only topological information of the target circuit and reachability information of the good circuit which was generated in the course of preprocess. Experimental results show that high fault coverage is obtained for synthesized Speed-Independent circuits and the use of the identification process decreases the number of tests and execution time.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.4
• /
• pp.1-10
• /
• 2008

The problem of controlling asynchronous sequential machines is addressed in this paper. Corrective control means to make behavior of an asynchronous sequential machine equal to that of a given model. The main objective is to develope a corrective controller, especially when a model is given as nondeterministic, or a set of reference models. The structure of corrective control system for asynchronous sequential machines is addressed first, followed by description of nondeterministic models. Then, we propose a method for analyzing reachability of asynchronous machines and nondeterministic models. Proposed methods are demonstrated in an example.

• Journal of KIISE:Software and Applications
• /
• v.30 no.3_4
• /
• pp.212-218
• /
• 2003

State invariant is a property that holds in every reachable state. It can be used not only in understanding and analyzing complex software systems, but it can also be used for system verifications such as checking safety, liveness, and consistency. For these reasons, there are many vital researches for deriving state invariant from finite state machine models. In previous works every reachable state is to be considered to generate state invariant. Thus it is likely to be too complex for the user to understand. This paper seeks to answer the question `how to simplify state invariant\ulcorner`. Since the complexity of state invariant is strongly dependent upon the size of states to be considered, so the smaller the set of states to be considered is, the shorter the length of state invariant is. For doing so, we let the user focus on some interested scopes rather than a whole state space in a model. Computation Tree Logic(CTL) is used to specify scopes in which he/she is interested. Given a scope in CTL, mixed reachability analysis is used to find out a set of states inside it. Obviously, a set of states calculated in this way is a subset of every reachable state. Therefore, we give a weaker, but comprehensible, state invariant.

• Journal of the Korean Mathematical Society
• /
• v.50 no.1
• /
• pp.17-39
• /
• 2013

The study of nonlinear discrete-time control dynamical systems with disturbance is an important topic in control theory. In this paper, we concentrate our efforts to multiple valued iterative dynamical systems, which model the nonlinear discrete-time control dynamical systems with disturbance. After establishing the validity of such modeling, we study the invariant set theory of the multiple valued iterative dynamical systems, including the controllability/reachablity problems of the maximal invariant sets.