• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.816-820
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• 2011

A method for increasing the difference of side-lobe level in spherical microphone array is presented. In array signal processing, it is known that narrow interval between sensors can increase the difference between main lobe and side-lobe of array response which eventually increase the source recognition capability. Recent commercial array being used, however, have shown certain limitation in using the number of sensors due to its costs and geometrical size of array. To overcome this problem, we have adapted MEMS sensors into spherical microphone array. To check out the improvement, two different types of spherical microphone array were designed. One array is composed with 32 regular instrument microphones and the other one is 85 MEMS sensors. Simulation and experiments were conducted on a sinusoidal noise source with two arrays. The time history data were analyzed with spherical harmonic decomposition and beamforming technique. 85 MEMS sensors array showed the improved side-lobe level suppression by more than 4 dB above the frequency content of 2 kHz compared to 32-sensor array.

• Genomics & Informatics
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• v.8 no.3
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• pp.138-141
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• 2010

Together with single nucleotide polymorphism (SNP), copy number variations (CNV) are recognized to be the major component of human genetic diversity and used as a genetic marker in many disease association studies. Affymetrix Genome-wide SNP 5.0 is one of the commonly used SNP array platforms for SNP-GWAS as well as CNV analysis. However, there has been no report that validated the accuracy and reproducibility of CNVs identified by Affymetrix SNP array 5.0. In this study, we compared the characteristics of CNVs from the same set of genomic DNAs detected by three different array platforms; Affymetrix SNP array 5.0, Agilent 2X244K CNV array and NimbleGen 2.1M CNV array. In our analysis, Affymetrix SNP array 5.0 seems to detect CNVs in a reliable manner, which can be applied for association studies. However, for the purpose of defining CNVs in detail, Affymetrix Genome-wide SNP 5.0 might be relatively less ideal than NimbleGen 2.1M CNV array and Agilent 2X244K CNV array, which outperform Affymetrix array for defining the small-sized single copy variants. This result will help researchers to select a suitable array platform for CNV analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.96-105
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• 2009

Photovoltaic array distance will be calculated that can have maximum output through the rearrangement of photovoltaic array by comparing and analyzing the power output decrease from the shadows of photovoltaic arrays according to the consideration of incidence angle that is not suitable to the situation of our country among the causes of power output decrease by sampling photovoltaic power generation plants. When relocate simulation result photovoltaic array 1 line, when relocate about 2.8[%], photovoltaic array 3 lines when relocate about 1.2[%], photovoltaic array 2 lines, output of about 5.0[%] improved. Also, gained space gains of photovoltaic array party 1.29[m] when relocate photovoltaic array party 0.82[m], 3 lines when relocate photovoltaic array party 0.39[m], 2 lines when relocate 1 line. As gains occur on photovoltaic array clearance, time that receive effect of shade was slowed down gradually and showed result that elevation of output shows finally.

• Journal of Biomedical Engineering Research
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• v.19 no.2
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• pp.129-132
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• 1998

A new one-channel phased-array quadrature RF coil is developed for spine MR imaging. Quadrature RF coils for MRI have been used to improve the signal-to-noise ratio (SNR) by$"\squt{2}"$ using two orthogonal RF coils in combination. More recently, the phased-array RF coil has been proposed for more improvement of SNR by using an array of reduced-size RF coil elements. Two schemes proposed for the new phased-array quadrature RF coil are:(1) Proper overlapping of two quadrature RF coils thus removing the mutual inductance and (2) Attaching preamplifiers right after the coil section and combining the signal with proper phase delays. The coil has been implemented for receive-only mode, and tested by phantom and volunteer imaging. The experimental results show the utility of the proposed RF coil.d RF coil.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.517-522
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• 2023

Existing radars have been developed by applying RF sub-array algorithms, and recently, fully digital Multiple-Input Multiple-Output (MIMO) radar algorithms have been implemented for vehicle radars. In this paper, the radar algorithm applying the Phased MIMO method to the hardware of the RF sub-array method, which is an unsecured technology, was implemented and verified in real time. In order to secure RF sub-array Phased MIMO algorithm technology, a hardware structure for FPGA-based real-time signal processing was presented, and performance was first predicted through design and simulation. Through this, the digital signal of FPGA-based broadband MIMO FMCW radar The processing hardware was developed, and the Phased MIMO radar algorithm of the RF sub-Array method was finally implemented and verified in real time. Based on this, it is judged that it will be possible to secure and apply core technologies necessary for terahertz band radar in the future.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.546-550
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• 2014

In this research, we report all the elements are placed in the space above the patient table as a transmit coil to give optimized B1+ field for the body object. Through the simulations, we compared upper-and-lower parts combined 8 channel Tx array to upper only 8 channel Tx array and showed the utilities of B1+ shimming in multi-channel Tx body imaging at 3T. Half-cylinder shaped upper array shows weak B1+ field area around back of patient without B1+ shimming. After B1+ shimming, highly induced SAR places occurred in the arm region due to the close distance to the both end elements which were driven by very high RF current to enhance B1+ in back area. The proposed upper and lower combined array provides an enhanced homogeneous B1+ field in large ROI imaging as a result of shimming over the body size phantom. Through this research we proved the usefulness of the proposed insertional upper and lower parts combined transmit array for 3T body imaging.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1871-1876
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• 2004

We demonstrate a novel fabrication technology for the microneedle array that can be used in the medical test field, which is transdermal drug delivery and blood analyte sampling. Previous researchers have used silicon-processed micromachining, a reactive ion etching, and molding techniques for the fabrication of microneedle array. However, these fabrication techniques have somewhat limitations apply to the microneedle array fabrication according to its application. Inclined LIGA process is suggested to overcome these problems. This process provides easier, sharper and longer out-of-plane microneedle array structure than conventional silicon-processed fabrication method did. Additionally, because of the advantage of the LIGA process based on mold fabrication for mass production, the polymer, PMMA(PolyMethylMethAcrylate), based microneedle array is useful as the mold base of nickel electroplating process; on the other hand, silicon-processed microneedle array is used in itself. In this research, we fabricate different types of out-of-plane microneedle array, which have different shape of tip, base and hole structure, using the inclined LIGA process. The fabricated microneedles have proper mechanical strength, height and sharpness to puncture human hand epidermis or dermis with less pain and without needle tip break during penetrating the skin.

• Journal of electromagnetic engineering and science
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• v.18 no.3
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• pp.175-181
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• 2018

The array patterns of a patch array antenna were calculated using an active element pattern (AEP) method that considers ground edge effects. The classical equivalent radiation model of the patch antenna, which is characterized by two radiating slots, was adopted, and the AEPs that include mutual coupling were precisely calculated using full-wave simulated S-parameters. To improve the accuracy of the calculation, the edge diffraction of a ground plane was incorporated into AEP using the uniform geometrical theory of diffraction. The array patterns were then calculated on the basis of the computed AEPs. The array patterns obtained through the conventional AEP approach and the AEP method that takes ground edge effects into account were compared with the findings derived through full-wave simulations conducted using a High Frequency Structure Simulator (HFSS) and FEKO software. Results showed that the array patterns calculated using the proposed AEP method are more accurate than those derived using the conventional AEP technique, especially under a small number of array elements or under increased steering angles.

• Journal of the Korean Vacuum Society
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• v.18 no.6
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• pp.488-493
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• 2009

We developed a simple method to control the length of carbon nanotube array by using oxygen plasma etching. In this way, we could obtain a carbon nanotube with a uniform length (20, 30, 50, $70\;{\mu}m$), that was parallel to the substrate. Moreover, our growing method of carbon nanotube array gives a uniform diameter ~3.5nm, which is consistent with our previous results. Using the same etching method, we demonstrated the carbon nanotube radio frequency identification (RFID) antenna. The results could be useful for carbon nanotube applications such as flexible and transparent conductive films.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1461-1466
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• 2003

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The characteristics of the frost formation on staggered fin array are somewhat different from those of in-line array. The frost layer at the first fin of the in-line array grows rapidly, compared to second fin, whereas the difference of the frost layer growth between the fins of the staggered array is small. For fin pitch below 10 mm, the frost layer growth of second fin in the staggered array is affected by that of first fin. The frost layer growth and heat transfer of single fin deteriorate with decreasing fin pitch regardless of fin array, however, the thermal performance of a heat exchanger, considering increase of heat surface area, becomes better.