• Journal of the Korean Society for Railway
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• v.9 no.2 s.33
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• pp.230-236
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• 2006

For a short-term measurement to reduce an accident on a railroad crossing, it is necessary to find out the weakness and problems of existing equipment in the railroad transportation system. The analysis of railroad crossing accidents shows that main causes of accidents (24.9%) are the careless driving including an engine problem, damage on the safety equipment, slide on the snow, and an engine stop on the railroad crossing. Therefore, it is required to install a sensor, or to make a crossing gate at the exist for detecting obstacles on a railroad to prevent collisions among trains. This paper suggests 'a panel sensor using the strain gauge' to make up the weaknesses of the sensing Dead Zone, which are caused by using a laser method, and to detect any small objects passing railroads in order to reduce the errors, which are occurred in the earth magnetic field for controlling Exit Slide Crossing Arm Detector. The device, suggested in this paper, is verified with detecting any small objects passing the railroad, with judging entry decision clearly, and with controlling passing gate and obstruction warnings/cautions obstacles at the same time, through an experimental test.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2610-2612
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• 1999

In controlling vector of induction motor, PID controller is required much time as the expert should control manually a gain of controller according to plant or a change of circumstances. Accordingly, this paper has gotten a gain of PID controller used neural network by self-funning method in order to settle above problem. The neural network can describe an input/output features in spite of non-linear system which is hard to get mathematical model by controlling the strength of connection by learning. It has a strong character against a distortion and noise of input information, and is suitable modeling of diver-variable system which is composed of several input/output. This paper has represented the self-tunning method for gain of PID controller used neural network when using PID controller to control speed of induction motor, and has checked strong characters against distortion and noise of input information through simulation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.1 no.1
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• pp.17-21
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• 2002

There are many problems of interoperability between ITS system equipments since the protocol standard for a network center and a node has not defined. In this paper, we consider the use of the SNMP to solve the interoperability problem, and apply the SNMP in the case of a CCTV as an example. Also, we defined its corresponding MIBs and accomplished the interoperability test, where the method of controlling the CCTV is explained and the data transmitted on the network are shown in a hexadecimal format. Our results are expected to be helpful for a guideline or feasibility test as nationwide data to support the interoperability of ITS systems between a network center and nodes.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.10
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• pp.988-993
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• 2009

In this paper, we deal with a tracking gain-up controller design problem to control effectively the shake of tracking actuator after a track seek. A minimum tracking gain-up open-loop gain can be calculated by estimating the shake of tracking actuator and a desired transient specification is considered to diminish effectively the shake of actuator. A tracking gain-up controller is designed by considering a robust $H_{\infty}$ control problem with a regional stability constraint. The proposed tracking gain-up controller design method is applied to the track-following system of a DVD recording device and is evaluated through the experimental results.

• Journal of the Korea Society for Simulation
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• v.7 no.2
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• pp.137-152
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• 1998

One of the components that constitute the simulation models is the state variables whose values are determined by the time related simulation process. Embedding rule-based expert systems into the simulation models should provide a systematic way of handling these time-dependent variables without distracting the essential problem solving capabilities of the expert systems which are well suited for expressing the decision making function of complex cases. The expert system, however, is inefficient in dealing with the time elapsing characteristics of target system compare to the simulation models. To solve the problem, this paper provides an interruptible inference engine whose inferencing process can be interrupted when the variables' value, which are used as the parameters of the rules, are not yet determined due to the time dependent nature of the state variables. The process is resumed when the variables are ready. The elapse of time is calculated by time-advance function of the simulation model to which the expert system has been embedded. The example modeling shown exploits the embedded interruptible inferencing capability for the controlling and monitoring of metal grating process.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.9
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• pp.591-599
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• 1988

After the short-term dynamics due to the major disturbance are over, the power system may lead to viability crisis state wherein there is possibility of cascading damage. This paper presents an emergency control algorithm to alleviate the obstacles of system frequency or bus voltage during the viability crisis state. The algorithm considers the effects of controlling reactive power sources for load shedding and generation reallocation in order to alleviate the obstacles. The problem is decomposed into a subproblem I and a subproblem II. The former minimizes system frequency deviation from nominal value and the latter voltage violation of load buses. The optimization problem is solved by a reduced gradient technique which can handle a great number of inequality constraints more easily. It has been verified that the use of the proposed algorithm for IEEE 14 bus system alleviates the obstacles efficiently during the viability crisis.

• Journal of Distribution Science
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• v.14 no.8
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• pp.51-57
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• 2016

Purpose - If control-ownership disparity is large, managers will not actively reduce costs; rather, they will maintain unutilized resources or possess surplus resources even when sales decrease with the purpose of increasing personal utility from status, power, compensation, and prestige. These managers' utility maximizing tendencies cause cost stickiness. We examine whether asymmetric behavior related to costs becomes stronger when there is a large disparity between ownership and control rights. Research design, data, and methodology - We construct a regression model to examine the relationship between control-ownership disparity and cost stickiness. STICKY, a dependent variable representing cost stickiness is a value found using the method of Weiss (2010), and Disparity is an interest variable that shows control-ownership disparity. Results - This study is based from the unique situations in Korea, in which high control-ownership disparity is common in firms. Large control-ownership disparity was found to increase cost stickiness of corporations. Conclusions - The results of this study imply that controlling shareholders may be regarded as a threat to the interests of minority shareholders and corporate values especially when controlling shareholders have significant influence over managers or the power to make managerial decisions as owners of a corporation.

• Journal of Communications and Networks
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• v.17 no.5
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• pp.506-516
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• 2015

Wireless sensor networks (WSNs) are generally comprised of densely deployed sensor nodes, which results in highly redundant sensor data transmissions and energy waste. Since the sensor nodes depend on batteries for energy, previous studies have focused on designing energy-efficient medium access control (MAC) protocols to extend the network lifetime. However, the energy-efficient protocols induce an extra end-to-end delay, and therefore recent increase in focus on WSNs has led to timely and reliable communication protocols for mission-critical applications. In this paper, we propose an energy efficient and delay guaranteeing node scheduling scheme inspired by biological systems, which have gained considerable attention as a computing and problem solving technique.With the identification of analogies between cellular signaling systems and WSN systems, we formulate a new mathematical model that considers the networking challenges of WSNs. The proposed bio-inspired algorithm determines the state of the sensor node, as required by each application and as determined by the local environmental conditions and the states of the adjacent nodes. A control analysis shows that the proposed bio-inspired scheme guarantees the system stability by controlling the parameters of each node. Simulation results also indicate that the proposed scheme provides significant energy savings, as well as reliable delay guarantees by controlling the states of the sensor nodes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.3
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• pp.19-26
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• 2010

Since T-DMB commercial services have been launched, various broadcasting services such as DMB2.0, which provides interactive data broadcasting services, have emerged. Due to activation of T-DMB services, the needs of the existing video contents as well as new data contents are increasing. Especially, video contents are frequently reused because of the production cost of digitalized contents. In order to solve the problem occurring in the contents reusing process, this paper proposes the method controlling transfer rate by defining a numerical formula and verifies it through simulation.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.359-368
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• 2014

Process synchronization is one of the most difficult subject for students learning the Operating System courses. It is due to the fact that concurrent process environment, where many events occur at the same time, is difficult to understand for ordinary human who thinks only one thing at a time. Classical synchronization examples like the Bounded buffer problem or the Dining philosopher problem fail to hook attention and interest from lower grade students who just begin to study the Operating System courses in college because these examples are either too technical or too unrealistic. In this paper we propose another synchronization example named the Bank account problem as an alternative to the classical ones. Bank account problem is proved to succeed getting high interest and understanding from the student as it is easy and realistic, and almost every student has the experience using bank account in real life. Various synchronization subjects including controlling the execution sequence of each process, incorrect result due to the race conditions, use of semaphores, deadlock, and monitor are considered to apply them to the Bank account problem.