• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.325-328
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• 2001

In this work, Cell search which is one of the important abilities of W-CDMA system in Reyleigh s fading channel is studied by using Cell Searcher of asynchronous IMT-2000 system(3GPP) and Cell - search simulation. For the methods of cell search to optimize codes, three stages are considered: 1) slot synchronization, 2) frame synchronization, and 3) scrambling code identification. It is found that key system parameters such as Primary Synchronization Channel (P-SCH), Secondary L Synchronization Channel(S-SCH), and Common Pilot Channel (CPCH) loading factor are optimized. It is noted that the smaller Optimal threshold value, the larger SNR of the received singnal. Therefore, It is important that the optimal threshold value is selected in the region of SNR

• Journal of Power System Engineering
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• v.13 no.3
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• pp.11-19
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• 2009

This paper introduces a conceptual design of a combined scroll expander-compressor unit for a fuel cell. Since air discharged out of the fuel cell stack has still high pressure energy, some power can be extracted from the air by directing it to pass through an expanding device. Such extracted power can be used to drive an auxiliary compressor. For this purpose, a scroll type expander coupled to a scroll type compressor was designed for a 1kW-class fuel cell. The orbiting scroll members of the expander and the compressor were made to share three of common drive shafts installed in the mid frame plate. Performance analysis for the combined expander-compressor unit showed that the installation of this unit could reduce the auxiliary power consumption in the fuel cell by about 42%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.1
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• pp.85-91
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• 2009

Recently, the LCD has high market share in TV market. The use of motion images in portable devices like DMB, PMP and Cell Phone is growing rapidly. One of the technique of enhancing the LCD's characteristic which is the slow response time. But, the technique requires a lot of memory usage, because of the requirement of frame memory. In this paper, we propose a reduction method for the frame memory that is required for LCD overdrive. Proposed overdrive architecture based on modified DWT-Inverse DWT and Color Conversion. The proposed architecture has a considerable PSNR. At once, it uses 50% of frame memory size and reduces 15% of frame memory size compare with previous architecture. The design was implemented using Xilinx Vertex4 and had 2172 Slice except Memory.

• Korea-Australia Rheology Journal
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• v.18 no.4
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• pp.171-181
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• 2006

We present a short review for authors' previous work on direct numerical simulations for inertialess hard particle suspensions formulated either with a Newtonian fluid or with viscoelastic polymeric fluids to understand the microstructural evolution and the bulk material behavior. We employ two well-defined bi-periodic domain concepts such that a single cell problem with a small number of particles may represent a large number of repeated structures: one is the sliding bi-periodic frame for simple shear flow and the other is the extensional bi-periodic frame for planar elongational flow. For implicit treatment of hydrodynamic interaction between particle and fluid, we use the finite-element/fictitious-domain method similar to the distributed Lagrangian multiplier (DLM) method together with the rigid ring description. The bi-periodic boundary conditions can be effectively incorportated as constraint equations and implemented by Lagrangian multipliers. The bulk stress can be evaluated by simple boundary integrals of stresslets on the particle boundary in such formulations. Some 2-D example results are presented to show effects of the solid fraction and the particle configuration on the shear and elongational viscosity along with the micro-structural evolution for both particles and fluid. Effects of the fluid elasticity has been also presented.

• Journal of Power Electronics
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• v.19 no.2
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• pp.487-496
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• 2019

For a solid-state transformer (SST), some factors, such as signal delay, switching loss and differences in the system parameters, lead to unbalanced DC-link voltages among the cascaded H-bridges (CHB). With a control method implemented in the ${\alpha}{\beta}$ frame, the DC-link voltages are balanced, and the reactive power is equally distributed among all of the H-bridges. Based on the ${\alpha}{\beta}$ frame control, the system can achieve independent active current and reactive current control. In addition, the control method of the high-voltage stage is easy to implement without decoupling or a phase-locked loop. Furthermore, the method can eliminate additional current delays during transients and get the dynamic response rapidly without an imaginary current component. In order to carry out the controller design, the vector refactoring relations that are used to balance DC-link voltages are derived. Different strategies are discussed and simulated under the unbalanced load condition. Finally, a three-cell CHB rectifier is constructed to conduct further research, and the steady and transient experimental results verify the effectiveness and correctness of the proposed method.

• Korean Journal of Crystallography
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• v.7 no.2
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• pp.191-195
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• 1996

Geometrical calculations are often more easily made in an orthonormal than in a crystallographic frame. In this paper a rational for the transformation from a triclinic cell data and atomic coordinates to orthonormal ones has been shown and a computer program has been made for the transformation.

• Journal of Microbiology and Biotechnology
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• v.7 no.4
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• pp.223-228
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• 1997

A DNA fragment containing the gene for cell wall hydrolase of alkalophilic Bacillus subtilis BL-29 was cloned into E. coli JM109 using pUC18 as a vector. A recombinant plasmid, designated pCWL45B, was contained in the fragment originating from the alkalophilic B. subtilis BL-29 chromosomal DNA by Southern hybridization analysis. The nucleotide sequence of a 1.6-kb HindIII fragment containing a cell wall hydrolase-encoding gene was determined. The nucleotide sequence revealed an open reading frame (ORF) of 900 bp with a concensus ribosome-binding site located 6 nucleotide upstream from the ATG start codon. The primary amino acid sequence deduced from the nucleotide sequence revealed a putative protein of 299 amino acid residues with an M.W. of 33, 206. Based on comparison of the amino acid sequence of the ORF with amino acid sequences in the GenBank data, it showed significant homology to the sequence of cell wall amidase of the PBSX bacteriophage of B. subtilis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.8
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• pp.1146-1158
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• 1993

In this paper, parallel scrambling techniques are considered for practical use in the SDH transmission and the ATM transmission. In the ATM transmission, there are two ways of transmitting ATM cells - the SDH-based and the cell-based - and the corresponding scrambling techniques differ accordingly. For the SDH transmission and the SDH-based ATM transmission, the FSS (frame synchronous scrambling) is applied to the STM frames : while for the cell-based ATM trans-mission, the DSS(distributed sample scrambling) is used on the ATM cell stream. The parallel scrambling techniques are examined for the FSS and the DSS, and applied to achieve the parallel FSSs for use in the SDH and the SDH-based ATM transmission along with the parallel DSS applicable to the cell-based ATM transmission. The resulting(8, 4) PSRG(parallel shift resister generator) and (8, 16) PSRG based parallel scramblings are directly applicable for the STM-1 rate processing of the STM-4 and STM-16 scramblings, respectively. Likewise, the resulting (1, 8)PSRG and double-sampling-double-correction based parallel scrambling techniques can be practically used for a low-rate processing of the SDH-based and the cell-based ATM signal scrambling respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8C
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• pp.667-679
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• 2010

The use of femtocells in buildings and homes has been widely studied as a means to enlarge the cell coverage and increase the network capacity of mobile communication systems. Femtocells for Mobile WiMAX (M-WiMAX) using time division duplexing (TDD) requires frame synchronization with neighboring base stations to avoid interference between uplink and downlink signals. In this paper, we propose a new frame synchronization method for femtocell using IEEE 802.11 based wireless backhaul, which transfers the time information of mobile network to femtocells via the beacon signal provided by IEEE 802.11. Also, in order to reduce timing error of the proposed method, we modify the collision avoidance scheme in the transmitter of IEEE 802.11 and apply a timing estimation technique designed in the sense of least squares to the receiver of IEEE 802.11. Through computer simulations using the proposed scheme, we evaluate the performance of frame synchronization for femtocells and show that the recovered timing information satisfies the timing specification defined by M-WiMAX standard.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.54-56
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• 2013

A subcarrier allocation scheme for base station (BS), relay station (RS) and mobile station (MS) can affect the performance of orthogonal frequency division multiple access (OFDMA) relay systems. In this paper, we propose a subcarrier allocation scheme with inter-cell interference and network coding in OFDMA relay systems. In the network coding zone, we consider an environment where RS can transmit a frame to BS and MS simultaneously. We divide an OFDMA frame into downlink zone, uplink zone, and network coding zone. The proposed scheme allocates subcarriers to BS, RS, and MS for each zone with consideration of inter-cell interference in OFDMA relay systems. We evaluate the performance of the proposed subcarrier allocation scheme through simulation.