• Structural Engineering and Mechanics
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• v.54 no.6
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• pp.1201-1216
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• 2015

This paper presents the details of size independent fracture energy and bi-linear tension softening relation for nano modified high strength concrete. Nano silica in powder form has been used as partial replacement of cement by 2 wt%. Two popular methods, namely, simplified boundary effect method of Karihaloo et al. (2003) and RILEM (1985) fracture energy with P-${\delta}$ tail correction have been employed for estimation of size independent fracture energy for nano modified high strength concrete (compressive strength ranges from 55 MPa to 72 MPa). It is found that both the methods gave nearly same values, which is an additional evidence that either of them can be employed for determination of size independent fracture energy. Bi-linear tension softening relation corresponding to their size independent fracture energy has been constructed in an inverse manner based on the concept of non-linear hinge from the load-crack mouth opening plots of notched three-point bend beams.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.12 no.2
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• pp.162-166
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• 2012

The instantaneous amplitude (IA) based on the higher order differential energy operator is proposed. And its general form for arbitrary order is also proposed. The various definitions of the IA and the instantaneous frequency (IF) estimators are considered. The IA and IF estimators based on the energy operators need less computational cost than the conventional IF and IA estimators exploiting the Hilbert transform. The IF and IA estimators are compared in terms of the frequency and amplitude tracking accuracy of the AM-FM signals. For noiseless case, the IA and IF estimators based on the Teager-Kaiser energy operator show better tracking performance than the IF and IA estimators based on the higher energy operators. However, under noisy condition, the IF and IA estimator based on the higher order energy operators with the order 3 and 4 show better tracking than the Teager-Kaiser energy based estimators. The IF and IA estimators are applied to signals in the various power anomalies to show their usefulness as the disturbance detectors.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.87-94
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• 2004

A number of approximate techniques have been developed to calculate the eigenvalues in a reduced manner. These schemes approximate the lower eigenvalues that represent the global behavior of the structures. In general, sequential elimination has been widely used with reliability. But it takes excessively large amount of time to construct a reduced system. The present study proposes two-level condensation scheme(TLCS). In the first step, the candidate elements are selected by element-level energy estimation. In the second step, master degrees of freedom are selected by sequential elimination from the candidate degrees of freedom linked to the selected elements in the first step. Numerical examples demonstrate that the proposed method saves computational cost effectively and provides a reduced system which predicts the accurate eigenvalues of global system.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.561-564
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• 2004

The motion estimation which requires huge computation consumes large power in a video encoder. Although a number of fast-search algorithms are proposed to reduce the power consumption, the smaller the computation, the worse the performance they have. In this paper, we propose an architecture that a low energy management scheme can be applied with several fast-search algorithm. In addition. we show that ECVH, a software scheduling scheme which dynamically changes the search algorithm, the operating frequency, and the supply voltage using the remaining slack time within given power-budget, can be applied to the architecture, and show that the power consumption can be reduced.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.31-36
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• 2001

As a part of micro engine development feasibility estimation was done through fabrication and test of down scaled combustor and MEMS fabricated spark electrode. In an experimental observation of the down scaled combustion phenomena where flame propagation was observed by optical method and pressure change in combustor which gives the information about the reaction generated thermal energy was recorded and analyzed. Optimal combustor scale was derived to be about 2mm considering increased heat loss effect and thermal energy generation capability. Through the fabrication and discharge test of MEMS electrode effects of electrode width and gap was investigated. Electrode was fabricated by thick PR mold and electroplating. From the result discharge voltage characteristic in sub millimeter scale electrode having thickness of $40{\mu}m$ was obtained. From the result base technology for design and fabrication of micro engine was obtained.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.260-265
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• 1995

Based on a thermohydraulic estimation of the level swell and shrinkage of the nuclear steam generators, a fuzzy logic controller is designed and tested to handle the problem of controlling the level swell and its restoration. The estimation is used to form an artificial system which is nearly the opposite of the level swell and shrinkage and a PD type controller is designed to control this system. This controller is added to a PI type ordinary fuzzy logic controller to form the proposed controller which is tested through various experiments on a scaled-down steam generator. It is found to perform efficiently so that the divergence of the level to a low limit can be avoided.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.135-143
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• 1999

This investigation evaluates effects of notch depth, fatigue precrack length and side groove in impact specimen for estimation of a valid K1d by instrumented Charpy impact test. Specimen material is 6005-T6. for notch depth 2.0mm and 2.5mm specimens or within about 2mm fatigue precrack length with notch depth 2.0mm and 2.5mm specimens or within about 2mm fatigue precrack length with notch depth 2.0mm , dynamic fracture toughness [$K_{1d,(1)}$] obtained by crack initiation load($P_m$) should be used. Dynamic fracture toughness of side grooved specimens are overestimated to that of standard impact specimen about 15 %-20%. It is confirmed that the formula of dynamic fracture toughness obtained by impact absorbed energy is inappropriate for ductile materials.

• Journal of the Korean Society for Marine Environment & Energy
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• v.2 no.1
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• pp.34-39
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• 1999

Removal of spilled oil over the sea and the river has become one of the urgent problems in these days. Removing oil using mechanical devices by adhesion method is known to be closely related with the problem of estimating the thickness of film remaining on the surface of solid withdrawn from a quiescent liquid. In the present study a series of experimental results are compared with the analytic estimation for the thickness of film remaining on the solid surface using non-dimensional analysis. For the case of pure water both results show the remarkable agreement. However, discrepancy has been found for the case of Bunker C oil and diesel oil. The analytic estimation over-predicts the experimental value for the case of Bunker C oil and under-predicts it for the case of diesel oil. Further study is required to investigate the real situation including a contact angle and the property difference between oil and water.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.60-61
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• 2014

Lithium-Ion batteries have become the best tradeoff between energy, power density and cost of the energy storage system in many portable high electric power applications. In order to manage the battery efficiently State of Charge (SOC) of the battery needs to be estimated accurately. In this paper a model-based approach to estimate the SOC of the Lithium-Ion battery based on the estimation of the battery impedance is proposed. The validity and feasibility of the proposed algorithm is verified by the experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.12-15
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• 1994

To establish the sea surface temperature estimation scheme for the upcoming advanced remote sensor, the quasi-analytical solution of the approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the non-linear equation. To solve the simultaneous approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the nonlinear equation. To solve the simultaneous approximated radiative transfer equation at each channel, the constrained non-linear optimization technique is adopted. To define the coefficients of the approximated radiative transfer equation and the constraints, the satellite detected radiance and the total transmittance are computed from the 1350 kinds of simulated atmosphere / surface models via radiative transfer code. The verification from the simulated data show the sufficient result.