• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.3
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• pp.313-319
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• 2017

This study presents a genetic algorithm (GA) to design a PID controller systematically for an inchworm operated by piezoelectric actuators. The performance index considering overshoot and settling time is adopted to search an optimal PID gain using GA. The piezoelectric actuator shows nonlinear characteristics including hysteresis and residual displacement. The PID feedback system combined with an integrator is used to improve the ability of tracking the complex input signals and suppressing the steady state error. The PID controller tuned by GA can track the various motion contours effectively. However, the PID controller shows an improper residual vibration under the application of high-frequency square input. The input shaper combined with the feedback system can overcome this limitation of the PID controller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.741-746
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• 2007

In this study, transfer path identification and output estimation are simulated by multi-dimension spectral analysis method (MDSA). Multi -input/single-output system give expression the vehicle suspension which each inputs are correlated reciprocally. In case of correlating with inputs, the system needs separating the each input signal by MDSA. Main simulations are about finding effective input by coherent output spectrum and selecting optimal input's number by multiple coherence function. Also, by shielding transfer path of each input, transfer path characteristic is identified in terms of overall integrated contribution level.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.7
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• pp.756-763
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• 2008

This paper presents an inchworm with three piezoelectric actuators. The dynamic stiffness of the inchworm is generally low compared to its driving condition, so mechanical vibration may degenerate the motion accuracy of the inchworm. The dynamic model of inchworm is identified by curve fitting technique based on the experimental frequency response function. For the precision motion control and low residual vibration of inchworm, driving input signal is designed by using cycloid step input and LQG control technique. Experimental result shows that proposed input shaping method is applicable effectively to the inchworm.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.10
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• pp.572-581
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• 2000

When the manipulator consisting of high ratio gear reducers at its joints is used as the slave manipulator in teleoperated systems, its dynamic characteristics is much slower than that of the master manipulator and it is likely to encounter the saturation in the input magnitude. The control input saturation generates an windup phenomenon that the system stability and position tracking performance of the slave manipulator are to be deteriorated. This paper proposes an force reflecting control scheme and its design method which compensates the control input saturation with absolute stability. The proposed scheme is shown to give a stable force reflection while compensating for control input saturation effectively.

• Journal of the Korean Regional Science Association
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• v.14 no.2
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• pp.51-64
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• 1998

This paper investigates how the factor inputs of firms are affected by the expectation about land-price increase in the future. We develope a two-factor (land and labor) model, in which expectation about land-price increase plays a key role in determining the "optimal" input level of labor and land. Expecting capital gains from input of the land when land price increases, firms input land up to the point where the marginal productivity of land falls short of the marginal cost of purchasing the land, in order to maximize the "joint-profit". That is, firms have an incentive to use more land than they do when capital gains are not expected. We mean joint-profit by profit in the standard sense plus capital gains. Once the land is input "excessively", the productivity of labor increase and labor is also input more, since land and labor are assumed as complementary in production. This mechanism works in the opposite direction when land price decrease. This paper suggests that land price fluctuation is a major destabilizer of an economy.or destabilizer of an economy.

• Journal of the Korean Regional Science Association
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• v.12 no.2
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• pp.1-19
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• 1996

The purpose of this paper is to evaluate the accuracy of input coefficients which are usually estimated by various non-survey methods. The resulting analysis showed that there were considerable differences employed. One of the interesting findings was that the simple LQ method was shown to be better then the other non-survey methods with respect to the degree of accuracy. And from a sensitivity analysis which was to show the effect of changes in input coefficients on the level of production by industry, an increase of 10% in the value of input coefficient (machinary and equipment setor) resulted up to 500billion Won in GRP for the case region. Therfore one of the implications which we can derive from the resulting analysis is that it necessary to pay attention to the key coefficients first to save out time and money, while retaining a certain level of accuracy. One thing to be noted, however, is that the key coefficients but the total effects which are calculated through the Leontief inverse matrices. Therfore to enhance the accuracty of input coefficients estimated by nonsurvey methods it is required to handle the relevant setoral data more carefully or to employ semi-survey method in part.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.14-19
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• 2004

The objective of the present work is to examine evaporation cooling of droplet due to surface roughness under radiative heat input condition. The surface temperatures varied from $80\~160^{\circ}C$ on aluminum alloy (AL 2024) and surface roughness was $0.18{\mu}m,\;1.36{\mu}m$. The results are as follows; Regardless of surface roughness under radiative heat input condition, as droplet diameter is larger, the in-depth temperature of solid decreases and evaporation time increases. In the case of $0.18{\mu}m\;and\;1.36{\mu}m$ of surface roughness, the larger the surface roughness is, the less the evaporation time is and the larger the temperature within the solid is. In the case of $Ra=0.18{\mu}m$ evaporation time and time averaged heat flux for radiative heat input case is shorter than for the conductive case.

• Journal of Hydrogen and New Energy
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• v.15 no.4
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• pp.341-347
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• 2004

An experimental study has been carried out on cooling perfonnance of a thennoelectric module. This problem is of particular interest in the design of the refrigeration systems using thermoelectric module, such as cosmetic refrigerator, wine cellar and air cooler. The effect of the input voltage and the hot side temperature on the cooling performance is studied in detail. The $\Delta$T, temperature difference between cold side and hot side surface of thermoelectric module, is described in terms of the input voltage and the hot side temperature. It is found that the cooling capacity can be improved by increasing the input voltage and by reducing the heat from the hot side of the thermoelectric module. However, COP is decreased with an increase in the input voltage, since power consumption is also increased. Thus, optimum input voltage can be selected based on cooling capacity and COP.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.41-47
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• 1997

A geographical resource analysis support system (GRASS) was incorporated to an input and output processor for the agricultural nonpoint source pollution (AGNPS) model. The resulting interface system, GIS-AGNPS was a user-friendly, menu-driven system. GIS-AGNPS was developed to automatically process the input and output data from GIS-based data using GRASS and Motif routines. GIS-AGNPS was consisted of GISAGIN which was an input processor for the AGNPS model, GISAGOUT a output processor for the AGNPS and management submodel. The system defines an input data set for AGNPS from attributes of basic and thematic maps. It also provides with editing modes so that users can adjust and detail the values for selected input parameters, if needed. The post-processor at the system displays graphically the outputs from AGNPS, which may he used to identify areas significantly contributing nonpoint source pollution loads.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.15-26
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• 2008

This paper proposes a new sinusoidal rectifier which improves input factor and input current waveform without complicated switching modulation such as pulse width or a complicated feed back control. The proposed rectifier consists of a pair of capacitors connected in series, a full bridge diode rectifier, a pair of inductors, and a pair of switching devices connected in series. While the configuration of the sinusoidal rectifier is simple in itself, it effectively reduces the reactive power and harmonics involved(IEC555-2 SC77A90 Class C) in input line current. The excellent properties of the new sinusoidal rectifier are verified by theoretical analysis and experimental results.