• Smart Structures and Systems
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• v.19 no.5
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• pp.513-521
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• 2017

The purpose of this paper is to study the capabilities of the impulse response method in length and flaw detecting for concrete piles and provide a suggested method to find small-size flaws in piles. In this work, wavelet transform is used to decompose the recorded time domain signal into a series of levels. These levels are narrowband, so the mix of different dominant bandwidths can be avoided. In this study, the impulse response method is used to analyze the signal obtained from the wavelet transform to improve the judgment of the flaw signal so as to detect the flaw location. This study provides a new way of thinking in non-destructive testing detection. The results show that the length of a pile is easy to be detected in the traditional reflection time or frequency domain method. However, the small flaws within pile are difficult to be found using these methods. The proposed approach in this paper is able to greatly improve the results of small-size flaw detection within piles by reducing the effects of any noise and clarifying the signal in the frequency domains.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.151.3-151
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• 2001

A design of PI controller to be used to control the first-order lag plus dead time process, such as a flow process, by the coefficient diagram method (CDM) is investigated. The factor of the dead time of process is first approximated to be the first-order by the Pade approximation. The response of the flow control system designed by CDM satisfy both transient and steady state specifications. However, the transient response generally still has long rise time. In order to improve the speed of the system response, a feedforward controller (FFC) is added into the PI control system. The structure of the FFC is a phase lead structure with two designed parameters and one derivative time obtained from the reaction curve of the flow process ...

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.110-119
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• 2000

In this paper, an experimental study is carried out under the operating conditions of low speed and rapid acceleration in order to investigate and improve the response characteristics of a turbocharged diesel engine with radial turbine driven by exhaust gas. A rapid acceleration for investigating the response performance is applied to the fuel-pump rack of the engine from 0-10% to 0-40% in steps of 10%, and accelerating time of 1, 2 and 3 seconds is applied to the engine. Further experiment for improving the low speed torque and acceleration performance is also performed by means of injecting air into the inlet manifold at compressor exit during the period of low speed and application of a rapid acceleration. The effects of air injection on the response performance are represented at subjected engine speed with the changes of response performance factors such as air injection pressure, air injection period, accelerating rate, accelerating time and load. From the experimental results obtained throughout this study, it is shown that air injection into the inlet manifold at compressor exit is closely related to the improvement of low speed and acceleration performance of a turbocharged diesel engine.

• Journal of the Korean Society for Precision Engineering
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• v.8 no.3
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• pp.64-72
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• 1991

This paper deals with the state estimator and controller. All state variables' feedback in the system were used to improve electro hydraulic servo sysem were used to improve electro hydraulic servo system's responese charact- eristics. Many gains of the state variables'and estimator's are produced by the algebraic Riccati equation, and every state variables'optimal gain and estimator gain is selected by trial and error method. For the designed estimator performance's examination, this paper simulate the time response for the step input, the reduced velocity output in subjected to load torque, and the time response for the step input in changing the inertiamoment.

• Journal of KIISE:Databases
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• v.32 no.3
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• pp.315-325
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• 2005

In mobile computing environments, a mobile host caches the data items to use the bandwidth efficiently and improve the response time of transactions. If the data items cached in mobile host are updated in the server, the server broadcasts an invalidation report for maintaining the cache consistency of mobile hosts. However, this method has a problem that the response time of mobile transactions can be long since their commit decision is delayed until receiving the invalidation report from the server In this paper, we propose the USR-MT method for improving the response time of mobile transactions. As the UGR-MT method can make a commit decision by using the data group information before receiving the invalidation report, the response time of mobile transactions can be improved. Also our method can improve the cache's efficiency since it prevents all the contents of a cache from being invalidated in the case that the disconnection of a mobile host is longer than the broadcast period of invalidation report.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.173-176
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• 1996

This paper deals with the problem of designing an adaptive regulator in order to improve transient performance in time-response when the linear state-space model of the plant contains unknown parameters which vary within prescribed bounds. The whole possible parameter space is divided into some subspaces and multiple models and controllers are established from the view point that each controller gives satisfactory transient behavior for systems corresponding to each parameter subspace. Based on time-response and an associated cost function, an appropriate controller is selected on-line out of multiple controllers.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1725-1731
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• 2003

A high level CVT ratio control algorithm is proposed to improve the engine performance by considering the powertrain response lag. In this algorithm, the desired CVT speed ratio is modified from the vehicle velocity, which is estimated after the time delay due to the powertrain response lag. In addition, the acceleration map is constructed to estimate the vehicle acceleration from the throttle pedal position and the CVT ratio. Using the CVT ratio control algorithm and the acceleration map, vehicle performance simulations are performed to evaluate the engine performance and fuel economy. It is found that the fuel economy can be improved about 3.6% for FUDS by the ratio control algorithm for the target vehicle. In selecting the appropriate time delay, compromise between the fuel economy and the acceleration performance is required.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.172-177
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• 2016

Miller feedback compensation is introduced in a low dropout regulator (LDO) in order to obtain a capacitor-free regulator and improve the fast transient response. The conventional LDO has a limited bandwidth because of the large-size output capacitor and parasitic gate capacitance in the power MOSFET. In order to obtain a stable frequency response without the output capacitor, LDO is designed with resistor-capacitor (R-C) compensation and this is achieved with a connection between the gain-stage and the power MOS. An R-C compensator is suggested to provide a pole and zero to improve the stability. The proposed LDO is designed with the 0.35 μm CMOS process. Simulation testing shows that the phase margin in the Bode plot indicates a stable response, which is over 100^o. In the load regulation, the transient time is within 55 μs when the load current changes from 0.1 to 1 mA.

• Carbon letters
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• v.12 no.1
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• pp.21-25
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• 2011

A novel electrode for an NO gas sensor was fabricated from electrospun polyacrylonitrile fibers by thermal treatment to obtain carbon fibers followed by chemical activation to enhance the activity of gas adsorption sites. The activation process improved the porous structure, increasing the specific surface area and allowing for efficient gas adsorption. The gas sensing ability and response time were improved by the increased surface area and micropore fraction. High performance gas sensing was then demonstrated by following a proposed mechanism based on the activation effects. Initially, the pore structure developed by activation significantly increased the amount of adsorbed gas, as shown by the high sensitivity of the gas sensor. Additionally, the increased micropore fraction enabled a rapid sensor response time due to improve the adsorption speed. Overall, the sensitivity for NO gas was improved approximately six-fold, and the response time was reduced by approximately 83% due to the effects of chemical activation.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.559-571
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• 2008

Platform Screen Door(PSD) has been installed and operated at seoul subway line $1\sim4$ in the manual train operation mode(ATS/ATC) by SeoulMetro since 2005. SeoulMetro uses the wireless (RF) communication system and the train door detection system for the link between the train and PSD doors opening/closing motion in the manual train operation mode. For the convenience and safety of passengers, the train doors and the PSD doors opening/closing shall be synchronized as much as possible. In ATO(Automatic Train Operation) mode which provides the interface between train control system and PSD system, ATO signaling system makes the train doors and PSD doors open/close command signals systematically, so PSD doors can be opened/closed almost simultaneously with the train doors. But, in the manual train control(ATS/ATC) mode, PSD system needs to detect the train doors open/close operation and make PSD open/close command signals to actuate PSD doors. These PSD open/close commanding process cause time delay of PSD doors opening/closing motion in response to the train doors opening/closing motion. Sometimes the response delay time can be over 1 second, which is not proper to operate PSD, and need to be reduced This paper presents the reduction method of the PSD response delay time to improve the convenience and safety of passengers.