• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.6
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• pp.663-671
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• 1988

In this paper, in order to reduce the blocking effect of block coded images, we propose the method considering the lowpass and bandpass components of Granrath's human visual model. This method consists of two-stage enhancement procedure. The first step is lowpass filtering which smooths out the blocking effect, and the second step is a high frequency enhancement procedure to increase the contrast decreased by the lowpass filtering in the first step. In the first step, the one-dimensional Gaussian filter which aligthns parallel to the edge direction is considered to preserve the edge in the block and the two-dimensional Gaussian filter is used to smooth out the blocking effect near the block boundaries. In the second step, the lowpass and bandpass components of the Granrath's model are considered to increase contrast in a restored image. The performance comparison of the proposed method and the existing mehtods is made by a computer simulation with several block coded images. We can see that the enhancement in the subjective quality of images of the proposed method is more significant than the enhancement in the subjective quality of images of the proposed method is more significant than the existing methods, though the proposed method does not show better performance on the PSNR gain, the poor measure of picture quality for block coded images.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1032-1037
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• 2016

In this paper, the method of isolation enhancement for the mobile phone MIMO antenna of LTE class 40(2300~2400MHz) was studied. Design of MIMO antenna was based on the hybrid antenna that operates both a monopole and an IFA(Inverted F Antenna). A structure for the isolation enhancement which controls induced electric field on the ground plane is located between MIMO antenna, and was not connected with the ground but apart 0.3mm. A MIMO antenna that operates on class 3~40(1710~2400MHz) of LTE service bands and a structure for the isolation enhancement at the class 10 band were designed. VSWR measurement of implemented antenna on the FR4 board showed within 3:1 at entire design bands, and isolation between antennas at the class 40 band was less than -30dB. Isolation was enhanced more than 20dB by the studied structure. ECC(Envelope Correlation Coefficient) for MIMO performance was under 0.1, and antenna average gain and efficiency measured in the anechoic chamber were -4.28~-1.40dBi and 37.32~72.36% respectively.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.529-534
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• 2009

One of the characteristics of the hearing impaired is that their frequency selectivity is poorer than that of the normal hearing. To compensate this, formant enhancement algorithms and spectral contrast enhancement algorithms have been developed. However in some cases, these algorithms fail to improve the frequency selectivity of the hearing impaired. One of the reasons is the acoustic masking among enhanced formants. In this study, we tried to enhance the formants based on the individual masking characteristic of each subject. The masking characteristic used in this study was minimum level difference (MLD) between the first formant to the second formant while acoustic masking was occurred. If the level difference between the two formants in each frame is larger than the MLD, the gain of the first formant was decreased to reduce the acoustic masking that occurred among formants. As a result of the speech discrimination test, using formant enhanced speeches, speech discrimination score (SDS) of the speeches having differently enhanced formants was significantly superior to SDS of the speeches having equally enhanced formants. It means that suppression of the acoustic masking among formants improve frequency selectivity of the hearing impaired.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.147-153
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• 2009

In this paper, FSS(Frequency Selective Surface) using defect mode characteristic is proposed. The unit cell using defect mode characteristic of the proposed FSS is offered lower resonant frequency in the same cell size. The number of suitable array is optimized 13 by 13. Also, the patch antennas operated in WCDMA(Wideband Code Division Multiple Access) Tx band and Rx band are designed for the comparison. The gain value of proposed FSS-1 complex structure (the patch antenna of Tx band and FSS) is improved 3.3 dB from 9.98 dBi to 13.28 dBi in Tx band. The gain value of proposed FSS-2 complex structure(the patch antenna of Rx band and FSS) is improved 5.53 dB from 9.81 dBi to 15.34 dBi in Rx band. Also the measured impedance bandwidth($VSWR{\leq}2$) of manufactured $13{\times}13$ array antenna is from 337 MHz(1.87 to 2.21 GHz). The measured radiation gain is 11.39 dBi(1.94 GHz), 13.11 dBi(2.05 GHz), 11.09 dBi(2.14 GHz). The measured radiation efficiency is 81 %. Because the proposed FSS structure has more higher gain, it will be applied to antenna of WCDMA repeater system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.52-60
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• 2009

In this pater, a CP-DRA(Circularly Polarized Dielectric Resonator Antenna) using cross-slot-feed is studied to enhance the gain and axial ratio bandwidth. First, a single layer CP-DRA is studied as a reference for comparison. Then a new type of multilayer CP-DRA is proposed to enhance the gain and axial ratio bandwidth. In consideration of the antenna gain enhancement, the spacing between the elements of the multilayer CP-DRA is examined through analysis of the radiation performance of a 2$\times$2 planar amy of DRAs with a spacing of 0.7$\lambda_0$ and 1.2$\lambda_0$ using CST Microwave Studio. The measured result shows that the gain and bandwidth of the multilayer structure is approximately twice that of the single layer one. In the case of the array antenna in which the spacing between multilayer CP-DRA element is 1.2$\lambda_0$, a grating lobe is reduced, in contrast to what we can expect from a conventional antenna array. The gain is 13.4dBi and axial ratio bandwidth is 0.8GHz.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.46 no.4
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• pp.16-22
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• 2009

In this paper, we propose an auto gain/offset which considers the visibility of human visual system (HVS) and the histogram of a target image jointly. In the proposed method, the lower and upper clipping thresholds are determined to maximize the averaged visibility of the contrast-stretched image. The target image is then contrast-stitched by the gain and offset derived from the clipping thresholds. We define the visibility as a quantity related to the spatial JND, which means the threshold below which any change of a pixel from its textured neighbors is not recognized by the HVS. Experimental results show that the contrast-stretched images by the proposed method have better global and local contrasts compared to the results by some conventional methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.367-370
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• 2004

We fabricated SiGe BiCMOS devices, which are important for ultra high speed RF IC chips, by employing $0.35\mu{m}$ CMOS process. To meet with the requirement of low noise level with linear base leakage current at low VBE region, we try to minimize polysilicon/ silicon interface traps by optimizing capping silicon thickness and EDR(emitter drive-in RTA) temperature. We employed $200\AA$and $300\AA$-thick capping silicon, and varied the EDR process condition at temperature of $900-1000^\circ{C}$, and time of 0-30 sec at a given capping silicon thickness. We investigated current gain behavior at each process condition. We suggest that optimum EDR process condition would be $975^\circ{C}$-30 sec with $300\AA$-thick capping silicon for proposed $0.35\mu{m}$-SiGe HBT devices.

• Nutrition Research and Practice
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• v.7 no.5
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• pp.352-358
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• 2013

Korean pine nut oil (PNO) has been reported to have favorable effects on lipid metabolism and appetite control. We investigated whether PNO consumption could influence weight gain, and whether the PNO-induced effect would result in an improvement of immune function in high-fat diet (HFD)-induced obese mice. C57BL/6 mice were fed control diets with 10% energy fat from either PNO or soybean oil (SBO), or HFDs with 45% energy fat from 10% PNO or SBO and 35% lard, 20% PNO or SBO and 25% lard, or 30% PNO or SBO and 15% lard for 12 weeks. The proliferative responses of splenocytes upon stimulation with concanavalin A (Con A) or lipopolysaccharide (LPS), Con A-stimulated production of interleukin (IL)-2 and interferon (IFN)-${\gamma}$, and LPS-stimulated production of IL-6, IL-$1{\beta}$, and prostaglandin $E_2$ ($PGE_2$) by splenocytes were determined. Consumption of HFDs containing PNO resulted in significantly less weight gain (17% less, P < 0.001), and lower weight gain was mainly due to less white adipose tissue (18% less, P = 0.001). The reduction in weight gain did not result in the overall enhancement in splenocyte proliferation. Overall, PNO consumption resulted in a higher production of IL-$1{\beta}$ (P = 0.04). Replacement of SBO with PNO had no effect on the production of IL-2, IFN-${\gamma}$, IL-6, or $PGE_2$ in mice fed with either the control diets or HFDs. In conclusion, consumption of PNO reduced weight gain in mice fed with HFD, but this effect did not result in the overall improvement in immune responses.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.252-258
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• 2017

In this paper, the bandwidth and gain enhancement of a double-dipole quasi-Yagi antenna (DDQYA) using a modified balun and two directors is studied. The proposed DDQYA consists of two strip dipoles with different lengths, a ground reflector, which are connected through a coplanar strip line, and two directors. The modified balun is used to increase the bandwidth, whereas two directors are appended to the DDQYA to enhance the gain in the middle and high frequency band. The effects of the length and width of the first director on the antenna performance are analyzed, and final design parameters to obtain a gain over 7 dBi at 1.60-2.90 GHz band are obtained. A prototype of the proposed DDQYA is fabricated on an FR4 substrate, and the experimental results show that the antenna has a frequency band of 1.57-3.00 GHz for a VSWR < 2, and measured gain ranges 7.1-7.8 dBi at 1.60-2.90 GHz band.

• Journal of the Korean Magnetic Resonance Society
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• v.1 no.2
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• pp.103-111
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• 1997

Proper pulse sequences and experimental optimization for the 3D 15N edited TOCSY and NOESY spectra were described. Using sensitivity enhancement approach with coherent selection by pulsed field gradients described by Kay and co-workers, an considerable gain in sensitivity was achieved. The sensitivity was also improved by minimal water saturation using water flip-back pulse. Among the three types of TOCSY mixing pulse, named MLEV-17, DIPSI-2rc, DIPSI-2rc sequence gave the most sensitive spectrum. These results suggest an appropriate pulse sequence for for those 3D experiments for large proteins.