• Journal of the Korean Society of Industry Convergence
• /
• v.3 no.2
• /
• pp.149-154
• /
• 2000

The purpose of this study is to measure the compression temperature in cylinder by using the fine thermocouple. As for using the thermocouple, it's response time delay should be regarded, even if it is a fine one. So, the output of thermocouple needs some compensation. The compensation circuit, which consists of a differential and an adding circuit is used for the compensate the time lag. And the time constant of the compensation circuit is determined the time between the TDC and the maximum point of the thermocouple output. Using this compensation circuit, the compression temperature is investigated of the cylinder in the diesel engine.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.2516-2520
• /
• 2005

In this paper, finite impulse response (FIR) smoothers are proposed for discrete-time systems. The proposed FIR smoother is designed under the constraints of linearity, unbiasedness, FIR structure, and independence of the initial state information. It is also obtained by directly minimizing the performance criterion with unbiased constraints. The approach to the MVF smoother proposed in this paper is logical and systematic, while existing results have heuristic assumption, such as infinite covariance of the initial state. Additionally, the proposed MVF smoother is based on the general system model that may have the singular system matrix and has both system and measurement noises. Thorough simulation studies, it is shown that the proposed MVF smoother is more robust against modeling uncertainties numerical errors than fixed-lag Kalman smoother which is infinite impulse response (IIR) type estimator.

• 제어로봇시스템학회:학술대회논문집
• /
• 1987.10b
• /
• pp.370-375
• /
• 1987

Damping piston with an orifice in the piston head is utilized to improve the damping characteristics of a pneumatic push-push type rotary actuator. Through linearized analysis, the optimum size of orifice, which gives maximum damping effect at the frequency where damping is desired. most, is predicted. The frequency response test of teal system were carried out to see the effects of damping piston and to obtain true optimum size of orifice by trying orifices of various size near the predicted value. During the tests, both air and helium were tried as working fluid, and a lag-lead compensation circuit was incorporated to improve system dynamics. The finally chosen orifice size is a little bigger than that predicted from analysis, however it gives high damping effects for the finally designed pneumatic system enough to have wide frequency response bandwidth.

• Journal of Korea Water Resources Association
• /
• v.30 no.2
• /
• pp.97-106
• /
• 1997

Parameters of the Nash model were analyzed using similarity concepts for the hydrogeomorphologic and the time response characteristics, then the application of parameter estimation was performed for a basin where no data are available. The self-similarity was investigated to evaluate the similarity of hydrogeomorphologic characteristics and to derive a equation for the time of concentration. The relation between model parameters and time characteristics such as travel and lag time, were developed to obtain their properties of similarity. There were remarkable results about the assessment for basin similarity and the application to an ungaged basin in Wi stream basin.

• Transactions of The Korea Fluid Power Systems Society
• /
• v.1 no.4
• /
• pp.15-21
• /
• 2004

High speed on-off electro-magnetic valves have been used for pressure control or flow control in automotive or construction machine servomechanisms. These systems require quicker valve switching speed to improve control preciseness. The authors designed and manufactured an electric valve driver with quick response characteristics by using 3 power source type valve driver concept. In experiments by using a hydraulic system incorporating the new valve driver, the new driver shortened the switching lag time from 5 ms to 1.3 ms. And also the new driver showed excellent position tracking control performances.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.04a
• /
• pp.327-334
• /
• 2002

The global behavior of tube structures (including tube and tube(s)-in-tube constructions) is investigated for the behavioral characteristics of the structures and their performance in relation to the various structural parameters. The stiffness factor in terms of the axial stiffness of the columns and the bending stiffness of both columns and beams is chosen as a parameter to explain the global behavior of the structures. The shear-lag phenomenon is also discussed to explain the general behavior of the structures. Three types of tube structures, with various structural parameters, are analysed for the comparative study, and the results are compared to investigate the structural response and performance of such structures. As a result of the comparison it is obtained that the axial stiffness of the columns is the most important factor governing the response of the tube structures under lateral loading

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.24 no.3
• /
• pp.376-380
• /
• 1987

The closed-loop transfer function of 2-nd order PLL (phase-looked loop)of which loop filter has active-lag 1-st order is found. Considering the three criteria of system performance: the transient response time of the circuit, noise bandwidth by the linear analysis and stability which uses root-locus method, the optimum value of damping factor is 1.0 and the natural frequency which depends upon the signal frequency can be determined after consideration of the trade-off relationship between the transient response time and the noise bandwidth.

• Journal of Wetlands Research
• /
• v.13 no.2
• /
• pp.171-179
• /
• 2011

The main objective of this study is to estimate of the vegetation response induced by climate change to soil moisture. We investigated a relationship between vegetation activity and climate variables using Moderate Resolution Imaging Spectroradiometer (MODIS)-retrieved Normalized Difference Vegetation Index (NDVI) and soil moisture. NDVI which extracted from MODIS 13 Vegetation Indices Product was considered as an useful parameter to figure out a relationship with two types of soil moisture, which were observed at Rural Development Administration sites and estimated from Advanced Microwave Scanning Radiometer E (AMSR-E) satellite imagery. The correlation of MODIS-NDVI and ground measured soil moisture were observed, became much stronger when compared to soil moisture values with time lag (5days, 10days, 15days). The correlation patterns between NDVI and soil moisture with different time lag were related to soil texture. The results from this study will be useful to understand the role of vegetation in water balance control in various scales from regional to global climate change.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.2
• /
• pp.122-129
• /
• 2014

Identification of the whipping response out of the combined wave-vibration response of a flexible sea going vessel is one of the most interesting research topic from ship designer's point of view. In order to achieve this goal, a novel methodology based on the wavelet cross-correlation technique was proposed in this paper. The cross-correlation of the wavelet power spectrum averaged across the frequency axis was introduced to check the similarity between the combined wave-vibration response and impulse response. The calculated cross-correlation of the wavelet power spectrum was normalized by the auto-correlation of the each spectrum with zero time lag, eventually providing the cross-correlation coefficient that stays between 0 and 1, precisely indicating the existence of the impulse response buried in the combined wave-vibration response. Additionally, the weight function was introduced while calculating the cross-correlation of the two spectrums in order to filter out the signal of lower frequency so that the accuracy of the similarity check becomes as high as possible. The validity of the proposed methodology was checked through the application to the artificially generated ideal combined wave-vibration signal, together with the more realistic signal obtained by running 3D hydroelasticity program WISH-Flex. The correspondence of the identified whipping instances between the results, one from the proposed method and the other from the calculated slamming modal force, was excellent.

• Journal of Mechanical Science and Technology
• /
• v.20 no.4
• /
• pp.533-544
• /
• 2006

The amplitude and phase lag of surface deformation were determined for a compliant coating under the action of turbulent pressure fluctuations. For this purpose, pressure fluctuations were measured experimentally. The amplitude and duration of coherent wave train of pressure fluctuations were investigated using digital filtration. The transient response was calculated for stabilization of forced oscillations of the coating in approximation of local deformation. The response of coating was analyzed with considerations of its inertial properties and limited duration of coherent harmonics action of pressure fluctuations. It is shown that a compliant coating interacts not with the whole spectrum of pressure fluctuations, but only with a frequency range near the first resonance. According to the analysis, with increasing elasticity modulus of the coating material E, deformation amplitude decreases as 1/E, and dimensionless velocity of the coating surface decreases as $1/\sqrt{E}$. For sufficiently hard coatings, deformation amplitude becomes smaller than the thickness of viscous sublayer, while surface velocity remains comparable to vertical velocity fluctuations of the flow.