• Journal of IKEEE
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• v.11 no.4
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• pp.198-204
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• 2007

For parallel and serially concatenated trellis coded modulation (TCM), improved iterative decoding schemes with a simple mechanism are proposed and their performances are compared with those of conventional decoding schemes. Simulation results have shown that the proposed schemes have provided a considerable decoding gain in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels, even if they can be implemented by a simple modification of conventional decoding algorithms.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.97-100
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• 2001

This paper introduces that it minimizes interference between links at high speed trajectory tracking of 2-degree parallel link robot. And in spite of system uncertainty, it introduces controller design method which is satisfied with performance specification. To do these, we separate two channels from parallel link robot through ICD(Individual Channel Design) and design controller of each channel using QFT(Quantitative Feedback Theory). Finally, we make sure of robustness and excellence of QFT control1er through simulation and experiment.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.55-60
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• 2008

Turbulent flow characteristics on the gap of two parallel channels are investigated using LES(large eddy simulation) approach. Two parallel channels have the same cross-section area and are connected by the narrow channel named the gap. Turbulent flow near the gap makes the flow pulsation along the streamwise direction of two channels. The flow condition is the Reynolds number of $2.5{\times}10^{-5}$. We compared the predicted results with the previous experimental results and presented the axial mean velocity, turbulent intensities, Reynolds shear stresses and turbulent kinetic energy.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.4
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• pp.333-354
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• 2016

The present investigation deals, heat and mass transfer characteristics with the effect of slip on the hydromagnetic pulsatile flow through a parallel plate channel filled with saturated porous medium. Based on the pulsatile flow nature, exact solution of the governing equations for the fluid velocity, temperature and concentration are obtained by using two term perturbation technique subject to physically appropriate boundary conditions. The expressions of skin friction, Nusselt number and Sherwood number are also derived. The numerical values of the fluid velocity, temperature and concentration are displayed graphically whereas those of shear stress, rate of heat transfer and rate of mass transfer at the plate are presented in tabular form for various values of pertinent flow parameters. By increasing the slip parameter at the cold wall the velocity increases whereas the effect is totally reversed in the case of shear stress at the cold wall.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.661-669
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• 2000

DS-CDMA downlink distinguishes actual user by orthogonal spreading codes ,but its orthogonality may be lost by the multiple access interference(MAI) caused by the multipath channel. Therefore in this paper, we proposed the single-user receiver, which use linear channel equalizer to eliminate the interference due to multipath channel and to recover orthogonality and then use code-matched filter to detect transmitted data. Unlike existing research, which mainly assumed ideal channel information, we use pilot channel assisted methods that is a kind of transmission of a parallel reference method to estimate the channel coefficients. Especially we use guard symbols which are inserted periodically to estimate channel coefficients exactly without interference from user signal. The results show that we accepted an approximately ideal channel information and achieved excellent performance improvement using proposed receiver compared with the conventional receiver especially user populations are high.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.1
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• pp.55-63
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• 2016

New materials and shapes for a humidifying element were developed which outperformed the widely used crisscross glass wool Glasdek media design. The new material consists of 50% cellulose and 50% PET. The parallel channel configuration was devised to reduce excessive pressure loss caused by the reduced height (from 7.0 mm to 5.0 mm) of the crisscross configuration. For the same crisscross configuration, the humidification efficiency of the cellulose/PET element was 26% higher than that of the glass wool element. For the same cellulose/PET material, humidification efficiency of the parallel channel configuration was 14% higher than that of the crisscross configuration. As for the pressure drops, the cellulose/PET element was 2-52% higher than those of the glass wool element. For the same cellulose/PET material, the pressure drop of the parallel channel configuration was 14% higher than that of the crisscross configuration. Data were compared against the predictions from existing correlations and those by the proposed model.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.73-76
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• 2000

We investigate the stepwise parallel processing of the serial search which can success the co]1 search at low Ec/Io. The single path Rayleigh fading channel which is worst-case channel model is considered. The typical 3-step cell search is used. The probabilities of detection, miss and false alarm for each step are used in closed forms based on the statistics of CDMA noncoherent demodulator output. The optimal power allocation to each channel and The optimal number of post-detection integrations for each step is obtained. Also, the cumulative probability distribution of the average eel] search time for serial search methods are compared.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.11-18
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• 2006

Compound flow by confluence of two parallel flows through a convergent channel and its choking phenomenon are calculated by one-dimensional isentropic model and completely mixing model. Optical observations and pressure measurements for subsonic/subsonic compound flows are carried out and compared with the results of one-dimensional calculations. As a result, it is found that inlet conditions of one flow influence the behavior of the other flow as well as the choking condition and present experimental data agree well with the results of one-dimensional calculations.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1079-1083
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• 2009

In this study, the distribution of $CO_2$ in an evaporator with 10 parallel micro channel aluminum tubes are experimentally investigated. Each tube has 6 circular micro channels with a diameter of 0.8mm. The tubes are heated with electric resistance wires, and the distribution of $CO_2$ into each tube is investigated by measuring the outer wall temperature. The outer wall temperature was found to be higher at the exit part of the top tube. It is thought that the $CO_2$ vapor at the upper part of the header reduces the mass flow rate of $CO_2$ into the top tube.

• Journal of computational fluids engineering
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• v.17 no.3
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• pp.93-98
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• 2012

The injection molding process is suitable for manufacturing complicated plastic products. As the customer request higher quality products increase, realization of the precise dimensional and shape controls is getting more important. For this purpose it is important to obtain uniform cooling procedure over the whole surface of the high temperature molded plastic. Failure to this may lead to different shrinkage speed, internal stresses and unwanted shape deformations. It is necessary to distribute coolant flow rates to the main channel and to the sub-channels properly to insure uniform cooling process when there are parallel cooling channels. In this study, three-dimensional turbulent flow simulations for representative parallel cooling channels were performed. To insure the intended flow rate to each sub-channels, various shape designs for the channel system were investigated. The results show that as the Reynolds number increases the effect of shape design is more profound. Through the proper flow distribution, uniform cooling effects would be expected.