• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.281-284
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• 2004

This paper described an Enhanced-xVSB system for improving mobile/pedestrian reception performance to the ATSC DTV 8-VSB transmission standard. E-xVSB system can transmit a mixture of normal (8-VSB) stream and enhanced (robust) stream. The robust stream has a higher threshold of visibility (TOV) compared to the standard stream, and legacy receivers ignore the robust packets. Thus, Enhanced-xVSB system is fully backward compatible with a current ATSC standard. for mobile and portable reception support, E-xVSB system adopts a reduced constellation method as well as enhanced trellis-coded modulation scheme. E-xVSB system supports a variety of enhanced modulation schemes: Pseudo-2VSB, Enhanced-4VSB, modified Enhanced-8VSB and Hybrid-VSB. Proposed E-xVSB system performs well under serious dynamic multipath reception environment.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.100-110
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• 2008

It is not easy to monitor and identify all engine faults and conditions using conventional fault detection approaches like the GPA (Gas Path Analysis) method due to the nature and complexity of the faults. This study therefore focuses on a model based diagnostic method using Neural Network algorithms proposed for fault detection on a turbo shaft engine (PW 206C) selected as the power plant for a tilt rotor type unmanned aerial vehicle (Smart UAV). The model based diagnosis should be performed by a precise performance model. However component maps for the performance model were not provided by the engine manufacturer. Therefore they were generated by a new component map generation method, namely hybrid method using system identification and genetic algorithms that identifies inversely component characteristics from limited performance deck data provided by the engine manufacturer. Performance simulations at different operating conditions were performed on the PW206C turbo shaft engine using SIMULINK. In order to train the proposed BPNN (Back Propagation Neural Network), performance data sets obtained from performance analysis results using various implanted component degradations were used. The trained NN system could reasonably detect the faulted components including the fault pattern and quantity of the study engine at various operating conditions.

• Nuclear Engineering and Technology
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• v.42 no.5
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• pp.546-551
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• 2010

The objective of this research is to estimate the crack location and size of a carbon steel pipe by using a laser ultrasound guided wave for the wall thinning evaluation of an elbow. The wall thinning of the carbon steel pipe is one of the most serious problems in nuclear power plants, especially the wall thinning of the carbon steel elbow caused by Flow-Accelerated Corrosion (FAC). Therefore, a non-destructive inspection method of elbow is essential for the nuclear power plants to operate safely. The specimens used in this study were carbon steel elbows, which represented the main elements of real nuclear power plants. The shape of the wall thinning was an oval with a width of 120mm, a length of 80mm, and a depth of 5mm. The L(0,1) and L(0,2) modes variation of the ultrasound guided wave signal is obtained from the response of the laser generation/air-coupled detection ultrasonic hybrid system represent the characteristics of the defect. The trends of these characteristics and signal processing were used to estimate the size and location of wall thinning.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.838-843
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• 2008

Cause of struggling to escape from dependency of fossil fuels, the fuel cell and the Plug-in Hybrid Electric Vehicle (PHEV) draw attention in the all of the world. Especially, the Polymer Electrolyte Membrane Fuel Cell (PEMFC) systems have been anticipated for next generation's energy supplying system, and we can predict the PHEV will enlarge the market share in the next few years to reduce not only the air pollution in the metropolis but the fuel-expenses of commuters. This paper presents simulation results about the strategy of smart charging system for PHEV in the residential house which has 1 kW PEMFC cogeneration system. The smart charging system has a function of recommending the best time to charge the battery of PHEV by the lowest energy cost. The simulated energy cost for charging the battery based on the electricity demand data pattern in the house. The house which floor area is $132\;m^2$ (40 pyeong.). In these conditions, the annual gasoline, electricity, and total energy cost to fuel the PHEV versus Conventional Vehicle (CV) have been simulated in terms of cars' average life span in Korea.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.1
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• pp.99-104
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• 2014

Nowadays, various researches fulfill in many communication engineering area for B4G (Beyond Forth Generation). Next LTE-A (Long Term Evolution Advanced), MU-MIMO (Multi-User Multi Input Multi Output) method raises to upgrade throughput performance. However, the method of user selection is not decided because of many types and discussions in MU-MIMO system. Many existing methods are powerful for enhancing performance but have various restrictions in practical implementation. Fairness problem is primary restriction in this area. Existing papers emphasis algorithm to increase sum-rate but we introduce an algorithm about dealing with fairness problem for real commercialization implementation. Therefore, this paper introduces new user selection method in MU-MIMO system. This method overcomes a fairness problem in SUS (Semiorthogonal User Selection) algorithm. We can use the method to get a similar sum-rate with SUS and a high fairness performance. And this paper uses a hybrid method with SC-SUS (Superposition Coding SUS) algorithm and SUS algorithm. We find a threshold value of optimal performance by experimental method. We show this performance by computer simulation with MATLAB and analysis that results. And we compare the results with another paper's that different way to solve fairness problem.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1125-1131
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• 2013

Nowadays, embedded software development using the MATLAB/Simulink system is gradually emerging. Studies generating the parts of embedded S/W in a Rapid Prototype are presented. In this paper, a method to generate the entire embedded S/W of enhanced AC motor control is proposed. High performance motor control could not be achieved with the basic Simulink library and RAppID Toolbox library as it does not have PWM based Interrupt, an ASAC (Analog Sensing for AC Motors) function and other special functions of the Freescale MPC555x. Consequently, the required libraries for enhanced AC motor control are created by Legacy code tool, TLC (Target Language Compiler) and S-Function (System-Function) of MATLAB/ Simulink and utilized in the Rapid Prototype. Motor control performance and execution time are compared automatically to the generated-code S/W with the hand coded S/W. The IPMSM (Interior Permanent Magnet Synchronous Motor) and MPC5553 board that were designed as the AC motor controller for hybrid electrical vehicle are used for the test. The performances meet the requirements and satisfactory results are acquired.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1685-1688
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• 2002

Application Routing Load Balancing (ARLB) is a novel load balancing mode that combines QoS routing and load balancing in per application to support QoS far real-time application based on wired network. Zone Routing Protocol (ZRP) is a recent hybrid proactive/reactive routing approach in an attempt to achieve scalability of ad-hoc network. This routing approach has the potential to be efficient in the generation of control traffic than traditional routing schemes. Up to now, without proper load balancing tools, the ZRP can actually guarantee QoS for delay-sensitive applications when congestion occurred in ad-hoc network. In this paper, we propose the ARLB to improve QoS fur delay-sensitive applications based on ZRP in ad-hoc network when congestion occurred and to be forwarding mechanism fur route coupling to support QoS for real-time applications. The critical point is that the routing metric of ARLB is originally designed for wired network environment. Therefore, we study and present an appropriate metric or cost computation routing of ARLB for recently proposed ZRP over ad-hoc network environment.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.283-289
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• 2014

A Fresnel lens is an optical component which can be used as a cost-effective, lightweight alternative to conventional continuous surface optics. Fresnel lens solar concentrators continue to fulfill a market requirement as a system component in high volume cost effective Concentrating Photovoltaic (CPV) electricity generation. The basic principles of the fresnel lens are reviewed and some practical examples are described. To investigate the performance space of the Fresnel lens, a fast simulation method which is a hybrid between raytracing and analytical computation is employed to generate a cache of simulation data. Injection molders are warming up to the idea of cycling their tool surface temperature during the molding cycle rather than keeping it constant. Heat and cool process are now also finding that raising the mold wall temperature above the resin's glass-transition or crystalline melting temperature during the filling stage and product performance in applications from automotive to packaging to optics. This paper deals with the suitability of Fresnel lenses of imaging and non-imaging designs for solar energy concentration. The concentration fresnel lens confirmed machinability and optical transmittance and roughness measure through manufactured the prototype.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.7
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• pp.500-508
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• 2000

Basic design for single-phase active power filter, which aims at railway application provided with PWM-controlled converters, is comprehensively studied and its performance is presented in this paper. Active power filters are used to compensate railway signaling and public telecommunication interference due to the high-order harmonic currents generated in railway traction locomotives. A type of hybrid digital filter which is composed of low pass filter and high pass filter is proposed so that the desired harmonic reference current with accurate magnitude and phase shift can be extracted from catenary line current. A design criteria to determine input inductor L and output capacitor C is also described, considering voltage, current, PWM pattern, and switching frequency of the main converters. Finally, computer simulation and DSP-based experiments resulted from laboratory test are presented.

• KIEE International Transactions on Power Engineering
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• v.4A no.4
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• pp.254-261
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• 2004

Traditionally, electrical power systems had formed the vertically integrated industry structures based on the economics of scale. However, power systems have been recently reformed to increase their energy efficiency. According to these trends, the Korean power industry underwent partial reorganization and competition in the generation market was initiated in 2001. In competitive electric markets, accurate load data is one of the most important issues to maintaining flexibility in the electric markets as well as reliability in the power systems. In practice, the measuring load data can be uncertain because of mechanical trouble, communication jamming, and other issues. To obtain reliable load data, an efficient evaluation technique to adjust the missing load data is required. This paper analyzes the load pattern of historical real data and then the tuned ARIMA (Autoregressive Integrated Moving Average), PCHIP (Piecewise Cubic Interpolation) and Branch & Bound method are applied to seek the missing parameters. The proposed method is tested under a variety of conditions and also tested against historical measured data from the Korea Energy Management Corporation (KEMCO).