• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.147-156
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• 2004

This paper presents an implementation and performance analysis of an access channel decoder which exploits a diversity gain due to the independent magnitude of received signals energy at each of antenna elements of a smart antenna BTS (Base-station Transceiver Subsystem) operating in CDMA2000 1X signal environment. Proposed access channel decoder consists of a searcher supporting 4 fingers, Walsh demodulator, and demodulator controller. They have been implemented with 5 of 1 million-gate FPGA's (Field Programmable Gate Array) Altera's APEX EP20K1000EBC652 and TMS320C6203 DSP (digital signal processing). The objective of the proposed access channel decoders is to enhance the data retrieval at co]1-site during the access period, for which the optimal weight vector of the smart antenna BTS is not available. Through experimental tests, we confirmed that the proposed access channel decoder exploitng the diversity technique outperforms the conventional one, which is based on a single antenna channel, in terms of detection probability of access probe, access channel failure probability, and $E_{b/}$ $N_{o}$ in Walsh demodulator.r.r.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.1
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• pp.69-74
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• 2010

In a grid connected variable speed wind turbine, the PCC voltage and the wind power fluctuate as the wind velocity changed. And this voltage variation is changed due to location of PCC. This paper calculate the value of PCC voltage variation which is proportional to the product of the line impedance from the ideal generator to the PCC and the wind turbine output current. And to reduce this PCC voltage variation, this paper calculate the required reactive power analytically using the vector diagram method. Output reactive current is changed, if the reactive current is limited by inverter capacity or grid code have the margin of voltage variation. If the grid connected inverter is controlled by proposed algorithm, the PCC voltage variation is minimized though the wind turbine output change at random. To verify calculated voltage variation and required reactive power, this paper utilized Matlab and PSCAD/EMTDC simulation and real small wind turbine and power system in Sapsido, island in the Yellow Sea.

• Fire Science and Engineering
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• v.28 no.1
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• pp.52-57
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• 2014

In this paper, the unsteady incompressible Navier-Stokes equations coupled with energy equation were solved to find out the optimal location of electrical heat trace for anti-freeze of water inside the pipe for fire protection. Since the conduction equation of pipe was coupled with the natural convection of water, the analysis of conjugate heat transfer was conducted. A commercial code (ANSYS-FLUENT) based on SIMPLE-type algorithm was used for investigating the unsteady flows and temperature distributions in water region. From the numerical experiments, the isotherms and the vector fields in water region were obtained. Furthermore, it was found that the lowest part of the pipe cross-section was an optimal position of electrical heat trace assuming the constant thermal expansion coefficient of water since the minimum temperature of the water with the position is higher than those with the other positions.

• Fire Science and Engineering
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• v.29 no.6
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• pp.33-39
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• 2015

In this paper, a numerical experiment was conducted to find out the optimal location of electrical heat trace for anti-freeze of water inside the CPVC pipe for fire protection. The unsteady incompressible Navier-Stokes equations coupled with energy equation were solved. Since the conduction equation of pipe was coupled with the natural convection of water, the analysis of conjugate heat transfer was conducted. A commercial code (ANSYS-FLUENT) based on SIMPLE-type algorithm was used for investigating the unsteady flows and temperature distributions in water region. From the present numerical experiment, it has been found that the vector field of water inside the PVC pipe is opposite to the case of steel because of the huge difference of material properties of the two pipes. Furthermore, it was found that the lowest part of the pipe was an optimal position for electrical heat trace since the minimum water temperature of the case was higher than those of the other cases.

• Fire Science and Engineering
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• v.30 no.1
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• pp.49-56
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• 2016

This paper numerically examines, straight and twisted electrical heat trace installations for their anti-freezing effects on water inside a pipe. The unsteady incompressible Navier-Stokes equations coupled with an energy equation were solved to compare the two installation methods. The heat conduction of the pipe with a heat source interacts with the natural convection of the water, and the conjugate heat transfer was considered using a commercial code (ANSYS-FLUENT) based on a SIMPLE-type algorithm. Numerical experiments, were done to investigate the isotherms and the vector fields in the water region to extract the evolutions of the minimum and maximum temperatures of the water inside the pipe. There was no substantial difference in the anti-freezing effects between the straight and twisted. Therefore, the straight installation is recommended after considering the damage and short circuit behavior of the electrical heat trace.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.47-57
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• 2010

Subgrid scale stabilization method is applied to Woo and Liu(2004)'s extended Boussinesq FEM numerical model to eliminate the 2dx wiggles. In order to optimize the computational efficiency, Hessian operator is introduced and the matrix of velocity vector is combined to one matrix for solving matrix equations. The mass lumping technique is also applied to the matrix equations of auxiliary variables. The newly developed code is applied to simulate Vincent and Briggs(1989)' wave transformation experiments and the results show that the numerical solution is almost wiggle-free and it matches very well with experimental data. Due to improvement of computational efficiency and wiggle reduction, it is plausible to apply this model to a realistic problem such as harbor oscillation problems.

• Nuclear Engineering and Technology
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• v.44 no.4
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• pp.369-378
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• 2012

A load-following operation in APR+ nuclear plants is necessary to reduce the need to adjust the boric acid concentration and to efficiently control the control rods for flexible operation. In particular, a disproportion in the axial flux distribution, which is normally caused by a load-following operation in a reactor core, causes xenon oscillation because the absorption cross-section of xenon is extremely large and its effects in a reactor are delayed by the iodine precursor. A model predictive control (MPC) method was used to design an automatic load-following controller for the integrated thermal power level and axial shape index (ASI) control for APR+ nuclear plants. Some tracking controllers employ the current tracking command only. On the other hand, the MPC can achieve better tracking performance because it considers future commands in addition to the current tracking command. The basic concept of the MPC is to solve an optimization problem for generating finite future control inputs at the current time and to implement as the current control input only the first control input among the solutions of the finite time steps. At the next time step, the procedure to solve the optimization problem is then repeated. The support vector regression (SVR) model that is used widely for function approximation problems is used to predict the future outputs based on previous inputs and outputs. In addition, a genetic algorithm is employed to minimize the objective function of a MPC control algorithm with multiple constraints. The power level and ASI are controlled by regulating the control banks and part-strength control banks together with an automatic adjustment of the boric acid concentration. The 3-dimensional MASTER code, which models APR+ nuclear plants, is interfaced to the proposed controller to confirm the performance of the controlling reactor power level and ASI. Numerical simulations showed that the proposed controller exhibits very fast tracking responses.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.3
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• pp.1-10
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• 2000

This paper proposes a novel video coding system with rate control based on fractal algorithm To overcome the demerits of excessive amounts of coded bit generated by previous fractal coding methodology. the proposed system classifies the Image into three classes such as background, motion compensation, and fractal coding area. The motion vector for motion compensation, and the fractal offset value that is difference value between the predicted offset and the least-square approximated value are coded with variable length code The decision method which determines threshold value of partitioning quadtree is applied to the bit-rate control algorithm considering the quantity of currently generated bits and fixed channel bandwidth Experimental result shows that the proposed system enhances compression ratio 1.8 times higher than previous method for the same image quality, and performs efficient rate control for fixed channel bandwidth.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.2
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• pp.106-112
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• 2017

In the paper, we propose a levitation and a propulsion controller for the magnetic levitation logistic transportation system. The levitation controller is designed considering the mutual influence of the electromagnets to minimize roll and pitch movements. In order to solve the structural disadvantages of the magnetic levitation transportation system, we improve the problem of the existing controller by applying the exponential filter to the reference input. DSP-based control hardware is developed and the levitation control method is verified by levitation experiments to the air gap goal. The propulsion controller uses the space vector voltage modulation method. The propulsion controller is designed to follow the position and velocity profile by detecting the absolute position from the bar code information attached to the rail. The position control result shows satisfactory performance through the propulsion control reciprocating motion experiment.

• The Plant Pathology Journal
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• v.27 no.1
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• pp.37-43
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• 2011

Rice stripe virus (RSV) is one of serious epidemic pathogens for rice species grown in many Asian countries. Therefore, it is necessary to produce a diagnostic detection kit applicable in fields for RSV detection. In this study, RSV proteins that were derived from recombinant proteins and synthetic polypeptides as antigens were generated and were raised in rabbits for antiserum production. Among seven proteins in RSV, genes that code for NCP and NS3 proteins were cloned and subcloned into vector carrying His-tag protein and were expressed in E. coli. Of two recombinant proteins, only anti-NCP displayed stable hybridization signals in western blot analysis. Alternately, synthetic RSV polypeptides for CP, NCP, NS3 and NSvc4 we also generated and only antibodies against CP and NCP were very effective to detect RSV in both RSV infected rice and weed plants. However, antibodies against NS3 and NSvc4 showed weak specific bands as well as strong non-specific background due to the difference of viral proteins produced in the infected leaves. In summary, the antibodies generated against RSV proteins produced in this study will be useful for various assays such as for RSV diagnostic detection, immunoprecipitation, protein purification, and western blot analysis.