• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.3-3
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• 2000

Limit cycle analysis of attitude control system using gas jet thrusters is performed. Schmitt-Trigger and PD control laws are applied and solenoid valve time delay is considered. Phase plane method is used for calculation of characteristics of limit cycle. Important characteristics of resultant limit cycle such as frequency, amplitude, maximum rate, and duty ratio could be expressed analytically by proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.118.2-118
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• 2002

Uncertain time delay happens when the process reads the sensor data and sends the control input to the plant located at a remote site in distributed control system. As in the case of data network using TCP/IP, VDN that integrates both device network and data network has uncertain tim e delay. Uncertain time delay can cause degradation in stability of distributed control system based on VDN. This paper investigates the transmission characteristic of VDN and suggests a control scheme based on the Smith's predictor to minimize the effect of uncertain time delay. The validity of the proposed control scheme is demonstrated with tracking position control of experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.529-535
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• 2013

This paper considers the problem of robust stability for uncertain discrete-time interval time-varying delayed descriptor systems using any combinations of quantization and overflow nonlinearities. First, delay-dependent linear matrix inequality (LMI) condition for discrete-time descriptor systems with time-varying delay and quantization/overflow nonlinearities is presented by proper Lyapunov function. Second, it is shown that the obtained condition can be extended into descriptor systems with uncertainties such as norm-bounded parameter uncertainties and polytopic uncertainties by some useful lemmas. The proposed results can be applied to both descriptor systems and non-descriptor systems. Finally, numerical examples are shown to illustrate the effectiveness and less conservativeness.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.6
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• pp.629-636
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• 1988

The reduction of recovery time for delay, in the train movements, is generally realized through train operations in the shortest running time and it leads to maximum energy consumption. At the region of this shortest running time, the amount of energy consumption is sharply reduced according to the running time. So the effect for the energy savings can be largely obtained by furnishing a little spare time on train operations. In this paper, it has been modelized the delay and it's enlargement phenomena and formualted the relief patterns in order to restore the delay by restraint and relief of precedent traints. Also it has been proved the number of relief trains for minimum energy consumption exists and then represented one example of relief patterns.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.179-187
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• 2009

This study develops a real-time signal control algorithm based on sectional travel times and includes a field test and evaluation. The objective function of the signal control algorithm is the equalization of delay of traffic movements, and the main process is calculating dissolved time of the queue and delay using the sectional travel time and detection time of individual vehicles. Then this algorithm calculates the delay variation and a targeted red time and calculates the length of the cycle and phase. A progression factor from the US HCM was applied as a method to consider the effect of coordinating the delay calculation, and this algorithm uses the average delay and detection time of probe vehicles, which were collected during the accumulated cycle for a stabile signal control. As a result of the field test and evaluation through the application of the traffic signal control algorithm on four consecutive intersections at 400m intervals, reduction of delay and an equalization effect of delay against TOD control were confirmed using the standard deviation of delay by traffic movements. This study was conducted to develop a real-time traffic signal control algorithm based on sectional travel time, using general-purpose traffic information detectors. With the current practice of disseminating ubiquitous technology, the aim of this study was a fundamental change of the traffic signal control method.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.154-159
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• 2011

The effect of the ignition delay time gap is newly studied. The operational characteristics of the linked two pyrotechnic thrusters are affected by the time gap. Although two thrusters are simultaneously ignited, the time at which the pressure starts to rise in each thruster may not be synchronized. The characteristic of the system with the time gap is compared with that of the fully synchronized system without any time gap. Depending upon the magnitude of the time gap, the pressure-time profile and the ballistic performance are different. When two pyrotechnic thrusters have a time gap, the peak pressure of one thruster(in which the pressure is built up earlier) is increased and the other is decreased. As the time gap is increased, the peak pressure is converged into the maximum pressure. This maximum pressure can be obtained when only one thruster is activated. Because the maximum pressure is bounded, it is predicted that there isn't any catastrophic failures in the considered system. When the time gap is relatively small, the impulse of the combined force acting on the moving body is almost maintained. But the ballistic performance of the system with a large time gap should be carefully estimated because the reduction of the ballistic performance should not be easily neglected.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.49-55
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• 2007

The characteristics of auto-ignition and combustion process of a single droplet of emulsified fuel suspended in a high-temperature air chamber have been investigated experimentally with various droplet sizes, surrounding temperatures, and water contents. The used fuels was n-Decane and it was emulsified with varied water contents whose maximum is 30%. The high-speed camera has been adopted to measure the ignition delay and flame life time. It was also applied to observe micro-explosion behaviors. The increase of droplet size and chamber temperature cause the decrease of the ignition delay time and flame life-time. As the water contents increases, the ignition delay time increases and the micro-explosion behaviors are strengthened. The starting timings of micro-explosion and fuel puffing are compared for different droplet sizes and the amount of water contents.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.165-170
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• 1997

In this paper, we consider the aortic sinus baroreceptor, which is the most representative baroreceptors sensing the variance of pressure in the cardiovascular system(CVS), and propose heart activity control model to observe the effect of delay time in heart period and stroke volume under the regulation of baroreflex in arotic sinus. The proposed heart activity baroreflex regulation model contains CVS electric circuit sub-model, baroreflex regulation sub-model and time delay sub-model. In these models, applied electric circuit sub-model is researched by B.C.Choi and the baroreflex regulation sub-model transforms the input, the arotic pressure of CVS electric circuit sub-model, to outputs, heart period and stroke volume by mathematical nonlinear feedback. We constituted the time delay sub-model to observe sensitivity of heart activity baroreflex regulation model by using the variable value to represent the control signal transmission time from the output of baroreflex regulation model to efferent nerve through central nervous system. The simulation object of this model is to observe variability of the CVS by variable value in time delay sub-model. As simulation results, we observe three patterns of CVS variability by the time delay. First, if the time delay is over 2.5 sec, arotic pressure, stroke volume and heart rate is observed nonperiodically and irregularly. Second, if the time delay is from between 0.1 sec and 0.25 sec, the regular oscillation is observed. Finally, if time delay is under 0.1 sec, then heart rate and arotic pressure-heart rate trajectory is maintained in stable state.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3630-3638
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• 1996

An experimental study has been conducted to explore the behaviors of the radiative ignition of polymethylmetacrylate(PMMA) in a confined enclosure such as the ignition delay time, PMMA surface temperature, the ignition location and the ignition process. In addition, the effects of hot wall orientation on the ignition delay and PMMA surface temperature were studied. When the hot wall is located at the bottom, ignition delay time is the shortest. Ignition surface temperature becomes the lowest for the hot top wall case. These are due to buoyancy effect. Since the radiative heat flux of hot wall is rather lower than laser source, the ignition is considered to be controlled by the mixing process. Therefore, the ignition location, where appropriate mixture of fuel and oxygen exists, occurs near the hot wall. The flame propagates along the hot wall where there exists sufficient oxygen.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.530-535
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• 2004

This paper deals with the unknown input observer (UIO) design problem for a class of linear time-delay systems. A case in which the observer error can completely be decoupled from an unknown input is treated. Necessary and sufficient conditions for the existences of such observers are present. Based on Lyapunov stability theory, thedesign of the observer with internal delay is formulated in terms of linear matrix inequalities (LMI). The design of the observer without internal delay is turned into a stabilization problem in linear systems. Two design algorithms of UIO are proposed. The effect of the proposed approach is illustrated by two numerical examples.