• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1408-1414
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• 2015

The renewable energies such as photovoltaic power, wind power and biomass have grown to a greater extent as decarbonization techniques. The renewable energies are interconnected to power systems (or electrical grids) in order to increase benefits from economies of scale, and the extra attention is focused on the Grid Code. A grid code defines technical parameters that power plants must meet to ensure functions of power systems, and the grid code determined by considering power system characteristics is various across the country. Some TSO (Transmission System Operator) and ISO (Independent System Operator) have issued grid code for wind power and the special requirements for offshore wind farm. The main purpose of the above grid code is that wind farm in power systems has to act as the existing power plants. Therefore wind farm developer and wind turbine manufacturer have great difficulty in grasping and meeting grid code requirements. This paper presents the basic understanding for grid codes of developed countries in the wind power and trends of those technical requirements. Moreover, in grid code viewpoint, the active power control of wind power is also discussed in details.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.73-81
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• 2009

Wireless media communication has lower robustness and stability than wired communication because of narrow bandwidth and unstable channel state. To make up for the deficient points of wireless communication, we used the diversity effect of cooperation communication and the error correction effect of channel coding schemes. In this paper, the cooperative communication system with RCPC codes and Hybrid ARQ transmission scheme is proposed for improving reliability on wireless communication, and we executed these simulations. From the simulation results, proposed system is showed lower BER performance than legacy system. In addition, we confirm the fact that the channel state of Relay-node and source-node is more important than the channel state of Relay-node and destination-node.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.309-313
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• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (CDMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated. We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) for satellite broadcasting communications is considered. In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical CDMA network can be substantially improved by increasing the interleaver length and the number of iterations in the decoding process. The results of this paper can be applied to implement the satellite broadcasting communications.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.314-319
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• 2009

In this paper, the network performance of a turbo coded optical code division multiple access (COMA) system with cross-layer, which is between physical and network layers, concept is analyzed and simulated We consider physical and MAC layers in a cross-layer concept. An intensity-modulated/direct-detection (IM/DD) optical system employing pulse position modulation (PPM) is considered In order to increase the system performance, turbo codes composed of parallel concatenated convolutional codes (PCCCs) is utilized. The network performance is evaluated in terms of bit error probability (BEP). From the simulation results, it is demonstrated that turbo coding offers considerable coding gain with reasonable encoding and decoding complexity. Also, it is confirmed that the performance of such an optical COMA network can be substantially improved by increasing the interleaver length and the number of iterations in the decoding process. The results of this paper can be applied to implement the indoor optical wireless LANs.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.855-870
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• 2012

The paper deals with three main topics: a) the definition of System Thermal-Hydraulics (SYS TH), b) a historical outline for SYS TH and, c) the description of elements for reflection when planning research projects or improvement activities, this last topic being the main reason for the paper. Distinctions between basic thermal-hydraulics and computational Fluid-Dynamics (CFD) on the one side and SYS TH on the other side are considered under the first topic; stakeholders in the technology are identified. The proposal of Interim Acceptance Criteria for Emergency Core Cooling Systems in 1971 by US NRC (AEC at the time) is recognized as the starting date or the triggering event for SYS TH (second topic). The complex codes and the main experimental programs (list provided in the paper) constitute the pillars for SYS TH. Caution or warning statements are introduced in advance when discussing the third topic: a single person (or a researcher) has little to no possibility, or capability, of streamlining the forthcoming investments or to propose a roadmap for future activities. Nevertheless, the ambitious attempt to foresee developments in this area has been pursued without constraints connected with the availability of funds and with industrial benefits or interests. Demonstrating the acceptability of current SYS TH limitations and training in the application of those codes are mentioned as the main challenges for forthcoming research activities.

• Journal of Korea Multimedia Society
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• v.9 no.9
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• pp.1247-1256
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• 2006

VM(Virtual Machine) can be considered as a software processor which interprets the abstract machine code. Also, it is considered as a conceptional computer that consists of logical system configuration. But, the execution speed of VM system is much slower than that of a real processor system. So, it is very important to optimize the code for virtual machine to enhance the execution time. In this paper, we designed and implemented the optimizer for the virtual(or abstract) machine code(VMC) which is actually SIL(Standard Intermediate Language) that is an intermediate code of EVM(Embedded Virtual Machine). The optimizer uses the pattern matching optimization techniques reflecting the characteristics of the VMC as well as adopting the existing optimization methodology. Also, we tried a benchmark test for the VMC optimizer and obtained reasonable results.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.5
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• pp.24-28
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• 1985

In this paper, the cyclic product codes which are capable of correcting random erros and burst errors simultaneously have been designed and constructed. First, the procedure for product of two cyclic codes is shown and thin the encoder and decoder system using the (7,4) cyclic Hamming code and the (3,1) cyclic code is implemented. The micro-computer is used for experiment and the system consists of encoder, decoder and interface circuits. The encoder of cyclic product code is implemented by interlacing encoders while the decoder is implemented by cascading decoders that interlace error trapping decoders. In conclusion, cyclic product codas are easily decodable and are capable of correcting four random errors and eight-burst errors. Better performance is obtained with low error rate.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.69-78
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• 2005

RFID is a technique that plays an important role in identifying and tracking the movement of objects by inserting small chips in objects. It is somewhat similar to bar codes from the various points of applications, but is hopefully considered to lead to tremendous development by solving the present drawbacks of bar codes such as slow identification. Speed, low rate of identification, limitation on the distance of identification and on the amount of saving capacity. Through the development of RFID technique, revolutionary growth is anticipated in the area of logistics and commodity distributional systems. Futhermore, the self processing RFID makes the communications between man and objects possible, and through which introduction of ubiquitous atmosphere will be accelerated. Therefore RFID is considered as one of the most attracting area of investment by developed countries as well as Korea. In this paper, we analyze the world wide tendency on RFID, and propose the conditions for activating RFID industry and also suggest directions for national strategy for diffusing RFID.

• Nuclear Engineering and Technology
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• v.44 no.6
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• pp.561-586
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• 2012

This paper describes a summary of final prediction results by system-scale safety analysis codes during the OECD/NEA/CSNI ISP-50 exercise, targeting a 50% Direct Vessel Injection (DVI) line break integral effect test performed with the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS). This ISP-50 exercise has been performed in two consecutive phases: "blind" and "open" phases. Quantitative comparisons were performed using the Fast Fourier Transform Based Method (FFTBM) to compare the overall accuracy of the collected calculations. Great user effects resulting from the combination of the possible reasons were found in the blind phase, confirming that user effect is still one of the major issues in connection with the system thermal-hydraulic code application. Open calculations showed better prediction accuracy than the blind calculations in terms of average amplitude (AA) value. A total of nineteen organizations from eleven countries participated in this ISP-50 program and eight leading thermal-hydraulic system analysis codes were used: APROS, ATHLET, CATHARE, KORSAR, MARS-KS, RELAP5/MOD3.3, TECH-M-97, and TRACE.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.132-142
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• 2006

In this paper, we present a candidate high data rate space time coded OFDM system for short range personal networking. The system transmits the complex space time coded signals with a hybrid orthogonal frequency division multiplexing (OFDM) based on ultra wideband (UWB) pulses. The transmitted signals are sparse pulse trains modulated by a frequency selected from a properly designed set of frequencies. Additionally, a widely linear (WL) receive filter and a space time frequency transmission are designed by using two simple parallel linear detectors. To overcome the deeply fade in the propagation system, a beamforming combined with space time block codes also 따 e briefly discussed.