• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.3
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• pp.30-37
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• 2023

The PSCB girder bridge is a closed cross-section in which the top and bottom flanges and the web are integrated, and the structural characteristics are generally different from the bridges in which the girder and the floor plate are separated, so a maintenance plan that reflects the characteristics of the PSCB girder bridge is required. As a result of analyzing damage types by collecting detailed safety diagnosis reports of highway PSCB girder bridges, most of the deterioration and damage occurring during use is concentrated on the top flange. In particular, cracks in the bridge direction on the underside of the top flange occurred in about 70 % of the PSCB girder bridges to be analyzed, and these cracks were judged to be caused by indirect loads such as heat of hydration and drying shrinkage rather than structural cracks caused by external loads. In order to improve durability and reduce maintenance costs of PSCB girder bridges in use, it is necessary to control restraint drying shrinkage cracks from the design stage. Therefore, in this paper, the cracks caused by drying shrinkage under restraint, which is the main cause of cracks under the flanges of the top part of the PSCB girder bridge, were directly calculated using the Gilbert Model, and the influencing factors such as the amount of reinforcing bars, diameter and spacing of reinforcing bars were analyzed. As a result of the analysis, it was found that the crack width caused by restraint drying shrinkage exceeded the allowable crack width of 0.2 mm for reinforcing bars with a reinforcing bar ratio of 0.01 or less based on the H16 reinforcing bar and a reinforcing bar with a diameter greater than H19 based on the reinforcing bar ratio of 0.01. Finally, based on the results of the crack width review, a method for controlling the crack width of the top flange of the PSCB girder bridge was proposed.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1351-1354
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• 2002

Wind farm which are composed with wind turbine generators can be a good alternatives to solve environmental problem and solutions to cope with energy crisis for using wind energy. Until now, these wind turbine generators have been being studied on the viewpoint of only active power control for reducing the burden of main grid. In this control scheme, we might demand a reactive power compensator in order to make reparation for the reactive power produced from wind turbine generator itself. Therefore, if the reactive power as well as active power of wind turbine generator were controlled according to the demand of reactive power, the installation of a additional reactive power compensator could be reduced. This paper presents the control method of a active and reactive power for wind turbine generators by means of SVPWM(Space Vector Pulse Width Modulation) inverting method and describes a operational coordination of wind turbine generators. The proposed power control algorithm can simply produce the output power of wind turbine generator needed in wind farm, which can reduce the power of main grid more and exclude a supplementary reactive power compensator. We assumed that wind farm are composed with two kinds of wind turbine generators, AC/DC/AC and induction generator types.

• Korean Journal of Applied Biomechanics
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• v.21 no.4
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• pp.459-466
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• 2011

The purpose of this study was to analyze of obstacle gait using spatio-temporal and foot pressure variables in children with autism. Fifteen children with autism and fifteen age-matched controls participated in the study. Spatio-temporal and foot pressure variables was investigated using GAITRite pressure sensor system. Each footprint was divided into 12 equal trapezoids and after that the hindfoot, midfoot and forefoot analysis was developed. Independent t-test was applied to compare the gait variables between the groups. The results showed that the autism group were significantly decreased in velocity, cadence, cycle and swing time compared to the control group. The autism group were significantly increased in step width and toe out angle compared to the control group. The autism group were significantly increased at midfoot and forefoot of lateral part of footprint and forefoot of medial part of footprint in the peak time compared to the control group. The autism group were significantly increased at midfoot and hindfoot in $P^*t$, at midfoot in active area, and at hindfoot in peak pressure compared to the control group. In conclusion, the children with autism showed abnormal obstacle gait characteristics due to muscle hypotonia, muscle rigidity, akinesia, bradykinesia and postural control impairments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.61-64
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• 2003

A band function model paired comparison method (BMPC method) is a kind of a paired comparison methods. Considering the human ambiguities, the BMPC method expressing the human judgment characteristics as a monotonous increase function with some width. Since function types are not specified in a BMPC method, the solution is obtained from inequalities, and the solution is given as a domain. To solve the simultaneous inequalities, the sequential renew method is used in the previous BMPC method. However, the sequential renew method requires much computational effort and memories. Generally, in BMPC method, it is able to solve only a paired comparison table which has less 12-13 samples. For that purpose, a new fast solution algorithm is required. In this paper, we proposed a new “search vector method” which renews the solution domain without creating new edge vectors. By using the method, it is able to decrease the necessary memory spaces and time to solve. The proposed method makes it able to solve more than 15 samples paired comparison inspections which are impossible to solve by previous method.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.119-121
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• 2008

This paper is proposed a high Performance speed control of the synchronous reluctance motor through the SV-PWM(Space Vector Pulse Width Modulation) of FAM-PI(Fuzzy Adaptive Mechanism-PI). SV-PWM is controlled using FAM-PI control. SV-PWM can be maximum used maximum do link voltage and is excellent control method due to characteristic to reducing harmonic more than others. Fuzzy control has a advantage which can be robustly controlled. FAM-PI controller is changed fixed gain of PI controller using fuzzy adaptive mechanism(FAM) to match operating condition. The results on a speed controller of IPMSM are presented to show the effectiveness of the proposed gain tuner. And this controller is better than the fixed gains one in terms of robustness, even under great variations of operating conditions and load disturbance.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.266-273
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• 2006

In difference with the rotary type electrical machinery, the single-sided linear induction motor(SLIM) that generates the direct thrust, is widely used for the operation system of electrified railroad, lope-less elevation system, conveyer system, and so on. The operational principle of single-sided linear induction motor is constructively similar to the general rotary Induction motor It Is difficult to realize the complicate linear induction motor which is applied space vector pulse width modulation(SVPWM) system, but widely used in vector motor control system or servo control system because of its high performance in current control. In this paper, we has modeled the dynamic characteristic analyzing methode, and calculated efficiently the end effect by using equivalent circuit methode in the operating linear Induction motor control system.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.138-147
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• 1998

This paper describes design and implementation results of a fuzzy logic speed controller of EV(Electric vehicle)'s induction motor for the purpose of realizing comfortable driving. The fuzzy controller is suitable for speed control of EV since that without detailed knowledge about the induction motor, it is easier to design a well-performing speed control system with good stability. PWM wave for driving the induction motor is generated by space vector modulation method and all the control algorithms are realized digitally. The results of experiment show excellence of the proposed system and that the proposed system is appropriate to control the speed of induction motor for commercial EVs.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.59-66
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• 2007

Voice coil actuator is used linear motion system that requires precision positioning control. In order to control precision positioning of voice coil actuator, relation model between duty ratio and moving displacement of voice coil actuator is needed. This paper present a duty ratio - displacement model in PWM control of voice coil actuator. Transfer function of voice coil actuator is obtained by combining voice coil motor's equation of motion with the equation of circuit and characteristic of voice coil motor. Consider to initial condition of velocity and current, transfer function is transformed mathematical model. The induced model can predict output displacement, velocity and current according to duty ratio and amplitude. The model is verified by experimental tests such as velocity and displacement response of voice coil motor. Simulated results have tracking errors of less than 10 percent of experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.1
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• pp.150-155
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• 2009

Hysteresis current regulator has been used widely because of its simple principle and structure. However, when the current band width is too narrow or the applied voltage is relatively too high, the switching frequency increases abruptly and it makes large amount of heat. In this study, for single phase current control, the hysteresis current control is executed by adding 0 mode state and comparing the slope of the current reference, which decreases the switching frequency so much and make the current control much stable. These were proved with computer simulations.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.405-415
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• 2016

This paper presents a model predictive control for shunt active power filters in synchronous reference frame using space vector pulse-width modulation (SVPWM). The three phase load currents are transformed into synchronous rotating reference frame in order to reduce the order of the control system. The proposed current controller calculates reference current command for harmonic current components in synchronous frame. The fundamental load current components are transformed into dc components revealing only the harmonics. The predictive current controller will add robustness and fast compensation to generate commands to the SVPWM which minimizes switching frequency while maintaining fast harmonic compensation. By using the model predictive control, the optimal switching state to be applied to the next sampling time is selected. The filter current contains only the harmonic components, which are the reference compensating currents. In this method the supply current will be equal to the fundamental component of load current and a part of the current at fundamental frequency for losses of the inverter. Mathematical analysis and the feasibility of the suggested approach are verified through simulation results under steady state and transient conditions for non-linear load. The effectiveness of the proposed controller is confirmed through experimental validation.