• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.405-410
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• 1994

The purpose of this paper is to present the details of design procedure of a nonlinear regulator by Riemannian geometric approach and to applied it to the case of a double-effect evaporator. A nonlinear geometric model is proposed on a direct sum space of a state vector and a control vector as well as in the previous parers by the authors. The geometric model is derived by replacing the orthogonal straight coordinate axes of a linear system on the direct sum space with the curvilinear coordinate axes. The integral manifold of the geometric model becomes homeomorphic to that of fictitious linear system. For the geometric model a nonlinear regulator with a performance index is designed renewedly by the procedure of optimization. The construction method of the curvilinear coordinate axes on which the nonlinear system behaves as a linear system is discussed. To apply the above regulator theory to double-effect evaporators especially to the pilot plant at the University of Alberta, a suitable nonlinear model is determined by the plant dynamics. The optimal control law is derived through the calculation of the homeomorphism. As a result it is confirmed that the regulator is effective and superior to that of the conventional control.

• Journal of Electrochemical Science and Technology
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• v.9 no.1
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• pp.20-27
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• 2018

We describe a redox-enhanced electric double-layer capacitor (EDLC) that turns the electrolyte in a conventional EDLC into an integral, active component for charge storage-charge is stored both through faradaic reactions with soluble redox-active molecules in the electrolyte, and through the double-layer capacitance in a porous carbon electrode. The mixed-redox electrolyte, composed of vanadium and iodides, was employed to achieve high power density. The electrochemical reaction in a supercapacitor with vanadium and iodide was studied to estimate the charge capacity and energy density of the redox supercapacitor. A redox supercapacitor with a mixed electrolyte composed of 0.75 M NaI and 0.5 M $VOSO_4$ was fabricated and studied. When charged to a potential of 1 V, faradaic charging processes were observed, in addition to the capacitive processes that increased the energy storage capabilities of the supercapacitor. The redox supercapacitor achieved a specific capacity of 13.44 mAh/g and an energy density of 3.81 Wh/kg in a simple Swagelok cell. A control EDLC with 1 M $H_2SO_4$ yielded 7.43 mAh/g and 2.85 Wh/kg. However, the relatively fast self-discharge in the redox-EDLC may be due to the shuttling of the redox couple between the polarized carbon electrodes.

• Journal of Power Electronics
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• v.9 no.1
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• pp.109-116
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• 2009

This paper addresses the output control of a utility-connected double-fed induction machine (DFIM) for wind power generation systems (WPGS). DFIM has a back-to-back converter to control outputs of DFIM driven by the wind turbine for WPGS. To supply commercially the power of WPGS to the grid without any problems related to power quality, the real and reactive powers (PQ) at the stator side of DFIM are strictly controlled at the required level, which in this paper is realized with the Fuzzy PI controller based on the field orientation control. For the Sinusoidal Pulse Width Modulation (SPWM) converter connected to the rotor side of DFIG to maintain the controllability of PQ at the state side of DFIM, the DC voltage of the DC link capacitor is also controlled at a certain level with the conventional Proportion-Integral (PI) controller of the real power. In addition, the power quality at the grid connected to the rotor side of DFIM through the back-to-back converter is maintained in a certain level with a PI controller of the reactive power. The controllers for the PQ at the stator side of DFIM, the DC link voltage of the back-to-back inverter and the reactive power at the grid connected to the rotor side of DFIM are designed and simulated in the PSIM program, of which the result verifies the performance of the proposed controllers.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.278-284
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• 1998

This paper describes a l0b CMOS A/D converter (ADC) for HDTV applications. The proposed ADC adopts a typical multi-step pipelined architecture. The proposed circuit design techniques are as fo1lows: A selective channel-length adjustment technique for a bias circuit minimizes the mismatch of the bias current due to the short channel effect by supply voltage variations. A power reduction technique for a high-speed two-stage operational amplifier decreases the power consumption of amplifiers with wide bandwidths by turning on and off bias currents in the suggested sequence. A typical capacitor scaling technique optimizes the chip area and power dissipation of the ADC. The proposed ADC is designed and fabricated in s 0.8 um double-poly double-metal n-well CMOS technology. The measured differential and integral nonlinearities of the prototype ADC show less than ${\pm}0.6LSB\;and\;{\pm}2.0LSB$, respectively. The typical ADC power consumption is 119 mW at 3 V with a 40 MHz sampling rate, and 320 mW at 5 V with a 50 MHz sampling rate.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.11
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• pp.809-814
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• 2013

Summed area table (SAT) is a data structure in which the sum of pixel values in an arbitrary rectangular area can be represented by the linear combination of four pixel values. Since SAT serially accumulates the pixel values from an image corner to the other corner, a high-resolution image can yield overflow in a floating-point representation. In this paper, we present a new SAT construction technique, which accumulates only the residuals from the linearly-regressed representation of an image and thereby significantly reduces the accumulation errors. Also, we propose a method to find the integral of the linear regression in constant time using double integral. We performed experiments on the image reconstruction, and the results showed that our approach more reduces the accumulation errors than the conventional fixed-offset SAT.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.215-220
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• 2014

Most of studies on wave height algorithms that are using at buoys describe algorithms using double integral to determine the position data from the acceleration data measured from the accelerometer. but sometimes, it can involve some cumulative error in that process, and result in misjudgment or unstabe system. On the other hand, It is widely known that the motion of fluid particles on or underneath a linear progressive wave is periodic and elliptic. This fact is considered in this article and leads a improved algorithms with no integral processing.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.11
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• pp.1005-1012
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• 2011

In this paper, the effect of wrinkling on the failure behavior of thin membrane was studied using geometrically nonlinear shell element post-buckling analysis with global-local analysis strategy. In the analysis, double-edge notched and single-edge notched tensile specimen configurations were considered. The analyses were performed for both cases with allowing and suppressing the wrinkling deformation. The results were investigated focusing on the effect of wrinkle development on the variation of J-integral values at the cut tip. The effect of cut lengths and the specimen lengths were also systematically studied.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.494-499
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• 2013

In this paper, we present an optical encryption and information authentication of 3D objects considering wireless channel characteristics. Using the optical encryption such as double random phase encryption (DRPE) and 3D integral imaging, a 3D scene with encryption can be transmitted. However, the wireless channel causes the noise and fading effects of the 3D transmitted encryption data. When the 3D encrypted data is transmitted via wireless channel, the information may be lost or distorted because there are a lot of factors such as channel noise, propagation fading, and so on. Thus, using digital modulation and maximum likelihood (ML) detection, the noise and fading effects are mitigated, and the encrypted data is estimated well at the receiver. In addition, using computational volumetric reconstruction of integral imaging and advanced correlation filters, the noise effects may be remedied and 3D information may be authenticated. To prove our method, we carry out an optical experiment for sensing 3D information and simulation for optical encryption with DRPE and authentication with a nonlinear correlation filter. To the best of our knowledge, this is the first report on optical encryption and information authentication of 3D objects considering the wireless channel characteristics.

• Structural Engineering and Mechanics
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• v.21 no.2
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• pp.205-220
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• 2005

This paper presents the possibilities of adapting artificial neural networks (ANNs) to predict the dimensionless parameters related to the maximum contact pressures of an elasticity problem. The plane symmetric double receding contact problem for a rigid stamp and two elastic strips having different elastic constants and heights is considered. The external load is applied to the upper elastic strip by means of a rigid stamp and the lower elastic strip is bonded to a rigid support. The problem is solved under the assumptions that the contact between two elastic strips also between the rigid stamp and the upper elastic strip are frictionless, the effect of gravity force is neglected and only compressive normal tractions can be transmitted through the interfaces. A three layered ANN with backpropagation (BP) algorithm is utilized for prediction of the dimensionless parameters related to the maximum contact pressures. Training and testing patterns are formed by using the theory of elasticity with integral transformation technique. ANN predictions and theoretical solutions are compared and seen that ANN predictions are quite close to the theoretical solutions. It is demonstrated that ANNs is a suitable numerical tool and if properly used, can reduce time consumed.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.461-468
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• 2020

The improvements of the DeCART/MUSAD code system for uncertainty analysis of HTGR neutronic parameters are presented in this paper. The function for quantifying an uncertainty of critical-spectrumweighted few group cross section was implemented using the generalized adjoint B₁ equation solver. Though the changes between the infinite and critical spectra cause a considerable difference in the contribution by the graphite scattering cross section, it does not significantly affect the total uncertainty. To reduce the number of iterations of the generalized adjoint transport equation solver, the generalized adjoint B₁ solution was used as the initial value for it and the number of iterations decreased to 50%. To reflect the implicit uncertainty, the correction factor was derived with the resonance integral. Moreover, an additional correction factor for the double heterogeneity was derived with the effective cross section of the DH region and it reduces the difference from the complete uncertainty. The code system was examined with the MHTGR-350 Ex.II-2 3D core benchmark. The k_eff uncertainty for Ex.II-2a with only the fresh fuel block was similar to that of the block and the uncertainty for Ex.II-2b with the fresh fuel and the burnt fuel blocks was smaller than that of the fresh fuel block.