• Journal of the Korean Chemical Society
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• v.65 no.4
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• pp.254-259
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• 2021

The purpose of this work is the development of a method for an effective, less expensive, rapid, and simultaneous determination of three phenolic compounds (caffeic acid, gallic acid, and quercetin) widely present in food resources and known for their antioxidant powers. The method relies on partial least squares (PLS) calibration of UV-visible spectroscopic data. This model was applied to simultaneously determine, the concentrations of caffeic acid (CA), gallic acid (GA), and quercetin (Q) in six herb infusion extracts: basil, chive, laurel, mint, parsley, and thyme. A wavelength range (250-400) nm, and an experimental calibration matrix with 21 samples of ternary mixtures composed of CA (6.0-21.0 mg/L), GA (10.0-35.2 mg/L), and Q (6.4-17.5 mg/L) were chosen. Spectroscopic data were mean-centered before calibration. Two latent variables were determined using the contiguous block cross-validation procedure after calculating the root mean square error cross-validation RMSECV. Other statistic parameters: RMSEP, R², and Recovery (%) were used to determine the predictive ability of the model. The results obtained demonstrated that UV-visible spectrometry and PLS regression were successfully applied to simultaneously quantify the three phenolic compounds in synthetic ternary mixtures. Moreover, the concentrations of CA, GA and Q in herb infusion extracts were easily predicted and found to be 3.918-18.055, 9.014-23.825, and 9.040-13.350 mg/g of dry sample, respectively.

• Bulletin of the Korean Mathematical Society
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• v.50 no.5
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• pp.1623-1630
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• 2013

The aim of this paper is to prove that every quadratic formal power series ${\omega}$ can be expressed as a periodic non-simple continued fraction having period length one.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.374-376
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• 2005

In this paper, we presented our implementation of 3DES and HMAC-MD5 processing functionality in Intel? IXP 2400 platform. It can be used as encryption and authentication engine for VPNs such as IPsec and SSL.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.31-53
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• 2003

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.205.1-205.1
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• 2008

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.131-131
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• 1997

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.47-50
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• 2008

The unsteady vortical flow over ONERA 70-degree delta wing was simulated using RANS and DES flow solvers on hybrid unstructured meshes. A study of time accuracy is accomplished to determine the effects of time step and number of iteration in pseudo-time stepping on numerical solutions. The grid size test is also performed to demonstrate that DES can be used to capture more accurately the unsteady vortical flow features over RANS simulation.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1059-1062
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• 1998

This paper which can simulate FRIENDS(Flexible Reliable Intelligent Electrical eNergy Delivery System) model of distribution electrical system presents a new algorithm. In the operation of FRIENDS model, dispersed energy storage(DES) systems have an important role. We can use the active and reactive power of DES to control customer's voltage. In this, the former means load levelling operation and the later means voltage control operation of DES. We focus our research on load levelling operation of DES. We develope an algorithm to get an optimal capacity and operation schedule of DES and then apply it to the FRIENDS model. The results show the effectiveness of the proposed method.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.558-563
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• 2007

Detached Eddy Simulation(DES) is performed for turbulent flow of the $270^{\circ}$ bend at a Reynolds number of 56,690. A Fine grid generation is used near a wall in order to satisfy the wall boundary condition of y+<1. Turbulence models adopted for DES and Reynolds Average Navier Stokes(RANS) simulation are SST(Shear Stress Transfort) model. Solutions for both streamwise and circumferential velocity components are compared with the experimental data by Lee for $270^{\circ}$ bend and by Chang for $180^{\circ}$ bend.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.66-78
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• 2009

This paper introduces the design of a fuzzy logic controller in conjunction with direct torque control strategy for a Permanent Magnet synchronous machine. A stator flux angle mapping technique is proposed to reduce significantly the size of the rule base to a great extent so that the fuzzy reasoning speed increases. Also, a fuzzy resistance estimator is developed to estimate the change in the stator resistance. The change in the steady state value of stator current for a constant torque and flux reference is used to change the value of stator resistance used by the controller to match the machine resistance.