• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.513-522
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• 2019

It is not easy to refuel quickly and safely with 70 MPa hydrogen. This is because the temperature in the vehicle tank rises sharply due to Joule-Thomson effect, etc. Thus protocols such as SAE J2601 in the United States and JPEC-S 0003 in Japan were established. However, they have the problem of over-complexity and lack of versatility by setting the preconditions for hot and cold cases and introducing a number of look-up tables. This study was conducted with the ultimate goal of developing new protocols based on complete real-time communication. Thermodynamic models were made and programs were developed for hydrogen refueling simulations. Simulation results confirmed that there are five parameters in the influencing factors of the hydrogen refueling protocol.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.217-221
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• 2013

Quantum low-density parity-check (LDPC) codes based on the Calderbank-Shor-Steane construction have low encoding and decoding complexity. The sum-product algorithm(SPA) can be used to decode quantum LDPC codes; however, the decoding performance may be significantly decreased by the many four-cycles required by this type of quantum codes. All four-cycles can be eliminated using the entanglement-assisted formalism with maximally entangled states (ebits). The proposed entanglement-assisted quantum error-correcting code based on Euclidean geometry outperform differently structured quantum codes. However, the large number of ebits required to construct the entanglement-assisted formalism is a substantial obstacle to practical application. In this paper, we propose a novel class of entanglement-assisted quantum LDPC codes constructed using classical Euclidean geometry LDPC codes. Notably, the new codes require one copy of the ebit. Furthermore, we propose a construction scheme for a corresponding zigzag matrix and show that the algebraic structure of the codes could easily be expanded. A large class of quantum codes with various code lengths and code rates can be constructed. Our methods significantly improve the possibility of practical implementation of quantum error-correcting codes. Simulation results show that the entanglement-assisted quantum LDPC codes described in this study perform very well over a depolarizing channel with iterative decoding based on the SPA and that these codes outperform other quantum codes based on Euclidean geometries.

• Molecules and Cells
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• v.45 no.3
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• pp.158-167
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• 2022

Ubiquitin (Ub) is post-translationally modified by Ub itself or Ub-like proteins, phosphorylation, and acetylation, among others, which elicits a variety of Ub topologies and cellular functions. However, N-terminal (Nt) modifications of Ub remain unknown, except the linear head-to-tail ubiquitylation via Nt-Met. Here, using the yeast Saccharomyces cerevisiae and an Nt-arginylated Ub-specific antibody, we found that the detectable level of Ub undergoes Nt-Met excision, Nt-deamination, and Nt-arginylation. The resulting Nt-arginylated Ub and its conjugated proteins are upregulated in the stationary-growth phase or by oxidative stress. We further proved the existence of Nt-arginylated Ub in vivo and identified Nt-arginylated Ub-protein conjugates using stable isotope labeling by amino acids in cell culture (SILAC)-based tandem mass spectrometry. In silico structural modeling of Nt-arginylated Ub predicted that Nt-Arg flexibly protrudes from the surface of the Ub, thereby most likely providing a docking site for the factors that recognize it. Collectively, these results reveal unprecedented Nt-arginylated Ub and the pathway by which it is produced, which greatly expands the known complexity of the Ub code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3A
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• pp.179-187
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• 2012

In this paper, we propose an adaptive DFE (Decision Feedback Equalizer) based on LDPC (Low Density Parity Check) code for phase noise suppression and performance improvement. The proposed equalizer in this paper is applied for wireless repeater system. So as to meet ever increasing requirements on higher wireless access data rate and better quality of service (QoS), the wireless repeater system has been studied. The echo channel and RF impairments such as phase noise produce performance degradation. In order to remove echo channel and phase noise, we suggest a novel adaptive DFE equalizer based on LDPC code. The proposed equalizer helps to compensate RF impairments and improve the performance significantly better than used independently. In addition, proposed equalizer has less iteration number of LDPC code. So, the proposed equalizer system has low complexity.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.39-50
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• 2010

In this paper, we analyze and simulate the performance of a tactics mobile communication system based on ultra wide band (UWB) in multi-user interference (MUI) environments. This system adopts a double binary turbo code for forward error correction (FEC). Wireless channel is modeled a modified Saleh and Valenzuela (SV) model. We employ a space time block coding (STBC) scheme for enhancing system performance. System performance is evaluated in terms of bit error probability. From the simulation results, it is confirmed that the tactics mobile communication system based on UWB, which is encoded with the double binary turbo code, can achieve a remarkable coding gain with reasonable encoding and decoding complexity in multi-user interference environments. It is also known that the bit error probability performance of the tactics mobile communication system based on UWB can be substantially improved by increasing the number of iterations in the decoding process for a fixed cod rate. Besides, we can demonstrate that the double binary turbo coding scheme is very effective for increasing the number of simultaneous users for a given bit error probability requirement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1275-1283
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• 2014

Characteristics of PCM(Pulse Code Modulation) waveform are suitable for target tracking. Especially in terms of dwell time, it is desirable to detect and track a moving target with the single PCM waveform for a MFR(Multi-Function Radar) which carries out multiple tasks. General PCM waveform processing includes Doppler filter bank caused by the characteristics of ambiguity function, to detect target and estimate Doppler frequency, which induces hardware burden and computational complexity. We propose a ML(Maximum Likelihood) based Doppler estimator for a PCM waveform, which is the closed form suboptimal solution and computationally efficient to estimate Doppler frequency and detect a moving target.

• Journal of Convergence Society for SMB
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• v.2 no.1
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• pp.33-40
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• 2012

Recently, embedded environment suffers a huge change, by growth of hardware and turning to be software-controlled. This has improved embedded software complexity. It also brought us the limit of the old development way to resolve the problem. Model-driven development is one solution to solve the limit common software development by previous way, and it became a one uses for embedded environment also. In this paper, we propose model based development approach for embedded software, witch consists of diagram editor and automatic code generator. The diagram editors are implemented by GMF, which include additional functions to solve memory restrictions and concurrent execution problems without OS environment to a automatic code generator. In order to verify the generated code, it will be tested in main control model of UAV by replacing existing module with generated one.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.13-23
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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) 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 e interleaver length and e number of iterations in e decoding process. The results of this paper can be applied to implement the indoor optical wireless LANs.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.1
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• pp.57-68
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• 2004

Although variable-length codes (VLCs) increase coding efficiency using the statistical characteristics of the source data, they have catastrophic effects from bit errors in noisy transmission environments. In order to overcome this problem with VLCs, reversible variable-length codes (RVLCS) have recently been proposed owing to their data recovering capability. RVLCS can be divided into two categories: symmetrical and asymmetrical RVLCs. Although the symmetrical RVLC has generally more overheads than the asymmetrical RVLC, it has some advantages of simpler design and more efficient memory usage. However, existing symmetrical RVLCs still have high complexity in their code design and some room for improvement in coding efficiency. In this paper, we propose a new algorithm for constructing a symmetrical RVLC from the optimal Huffman code table. The proposed algorithm has a simpler design process and also demonstrates improved performance in terms of the average codeword length relative to the existing symmetrical RVLC algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9C
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• pp.537-545
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• 2011

This paper analyzed performance of three dimensional turbo code and turbo ${\Phi}$ codes proposed in the next generation DVB-RCS systems. In the view of turbo ${\Phi}$ codes, we proposed the optimal permutation and puncturing patterns for triple binary input data. We also proposed optimal post-encoder types and interleaving algorithm for three dimensional turbo codes. Based on optimal parameters, we simulated both turbo codes, and we confirmed that the performance of turbo ${\Phi}$ codes are better than that of three dimensional turbo codes. However, the complexity of turbo ${\Phi}$ is more complex than that of three dimensional turbo codes by 18%.