• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.85-91
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• 2007

Satellite Digital Multimedia Broadcasting (S-DMB) is the digital convergence service of broadcasting and communication for mobility and portability. Broadcasting service of S-DMB can be taken by the mobile phone or vehicle terminals anytime and anywhere. S-DMB system is currently providing 11 video channels and 26 audio channels. As the demand of multimedia service is recently increasing, S-DMB system needs high quality and new contents service. Therefore we need to make efficient S-DMB with more channel ability and high transmission quality. In this paper, we propose new S-DMB system that can be applied to powerful channel coding scheme and hierarchical 8-PSK(8-Phase Shift Keying) modulation with Backwards Compatibility modes that simultaneously can support both current and new system. And we analyze the performance of current S-DMB system and verify a possibility of advanced S-DMB through computer simulation.

• Smart Structures and Systems
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• v.15 no.6
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• pp.1463-1479
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• 2015

Lamb waves have been a promising candidate for quantitative damage identification for various engineering structures, taking advantage of their superb capabilities of traveling for long distances with fast propagation and low attenuation. However, the application of Lamb waves in damage identification so far has been hampered by the fact that the characteristic signals associated with defects are generally weaker compared with those arising from boundary reflections, mode conversions and environmental noises, making it a tough task to achieve satisfactory damage identification from the time series. With awareness of this challenge, this paper proposes a time reversal-based technique to enhance the strength of damage-scattered signals, which has been previously applied to bulk wave-based damage detection successfully. The investigation includes (i) an analysis of Lamb wave propagation in a plate, generated by PZT patches mounted on the structure; (ii) an introduction of the time reversal theory dedicated for waveform reconstruction with a narrow-band input; (iii) a process of enhancing damage-scattered signals based on time reversal focalization; and (iv) the experimental investigation of the proposed approach to enhance the damage identification on a composite plate. The results have demonstrated that signals scattered by delamination in the composite plate can be enhanced remarkably with the assistance of the proposed process, benefiting from which the damage in the plate is identified with ease and high precision.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1345-1353
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• 2007

The effect of salicylic acid(SA) on antioxidant system and protective mechanisms against UV-B induced oxidative stress was investigated in cucumber(Cucumis sativus L.) leaves. UV-B radiation and SA were applied separately or in combination to first leaves of cucumber seedlings, and dry matter accumulation, lipid peroxidation and activities of antioxidant enzymes were measured in both dose and time-dependant manner. UV-B exposure showed reduced levels of fresh weight and dry matter production, whereas SA treatment significantly increased them. SA noticeably recovered the UV-B induced inhibition of biomass production. UV-B stress also affected lipid peroxidation and antioxidant enzyme defense system. Malondialdehyde(MDA), a product of lipid peroxidation, was greatly increased under UV-B stress, showing a significant enhancement of a secondary metabolites, which may have antioxidative properties in cucumber leaves exposed to UV-B radiation. Combined application of UV-B and SA caused a moderate increase in lipid peroxidation. These results suggest that SA may mediate protection against oxidative stress. UV-B exposure significantly increased SOD, APX, and GR activity compared with untreated control plants. Those plants treated with 1.0 mM SA showed a similar pattern of changes in activities of antioxidant enzymes. SA-mediated induction of antioxidant enzyme activity may involve a protective accumulation of $H_2O_2$ against UV-B stress. Moreover, their activities were stimulated with a greater increase by UV-B+SA treatment. The UV-B+SA plants always presented higher values than UV-B and SA plants, considering the adverse effects of UV-B on the antioxidant cell system. ABA and JA, second messengers in signaling in response to stresses, showed similar mode of action in UV-B stress, supporting that they may be important in acquired stress tolerance. Based on these results, it can be suggested that SA may participates in the induction of protective mechanisms involved in tolerance to UV-B induced oxidative stress.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1199-1202
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• 2008

High mobility bottom gate thin film transistors (TFTs) with an amorphous gallium tin zinc oxide (a-GSZO) channel layer have been produced by rf magnetron cosputtering using a gallium zinc oxide (GZO) and tin (Sn) targets. The effect of the post annealing temperatures ($200^{\circ}C$, $250^{\circ}C$ and $300^{\circ}C$) was evaluated and compared with two series of TFTs produced at room temperature and $150^{\circ}C$ during the channel deposition. From the results it was observed that the effect of pos annealing is crucial for both series of TFTs either for stability as well as for improving the electrical characteristics. The a-GSZO TFTs operate in the enhancement mode (n-type), present a high saturation mobility of $24.6\;cm^2/Vs$, a subthreshold gate swing voltage of 0.38 V/decade, a turn-on voltage of -0.5 V, a threshold voltage of 4.6 V and an $I_{ON}/I_{OFF}$ ratio of $8{\times}10^7$, satisfying all the requirements to be used in active-matrix backplane.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.34-41
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• 1984

MOEN/MO double layer which is to be used It)r the RMOS (refractory metal oxide semiconductor) gate material has been fabricated by means of low temperature reactive sputtering in N2 and Ar mixture. Good Mo2N film was obtained in the volumetric mixture of Ar:N2=95:5. The sheet resistance of the fabricated Mo7N film was about 1.20 - 1.28 ohms/square, which is about an order of magnitude lower than that of polysilicon film, and this would enable to improve the operational speed of devices fabricated with this material. When PSG (phosphorus silicate glass) was used as impurity diffusion source for the source and drain of the RMOSFET in the N2 atmosphere at about 110$0^{\circ}C$, the Mo2N was reduced to Mo resulting in much smaller sheet resistance of about 0.38 ohm/square. The threshold voltage of the RMOSFET fabricated in our experiment was - 1.5 V, and both depletion and enhancement mode RMOSFETs could be obtained.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.905-914
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• 2008

The paper studied the scheme of applying the MPEG-4 SVC signal to the Ka band satellite broadcasting system through the JSCC system to resolve the rain fading problem generated when providing the Ka band HDTV satellite broadcasting service. The Ka band satellite broadcasting system is based on the VCM mode of the DVB-S2, and the SVC signal is considered as one of the spatial scalability, the SNR scalability and the temporal scalability. The JSCC system jointed all the layers of the source coding system and the channel coding system, and allocated bit rate to source coding and channel coding for each layer to get the optimum receiving quality. The layers are consists of a base layer and an enhancement layer, and the bit rate of each layer is affected by the SVC signal. The applicability of the three SVC signals to the Ka band satellite broadcasting service is analyzed with respect to the rain fading, and the scheme of applying the most excellent SVC to the service is considered.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.647-650
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• 2013

HEVC RExt(High Efficiency Video Coding Range Extension) set a goal to support RGB/YUV 4:2:2 4:4:4 color sampling and over 10 bit-depth images. Unlike the previous 4:2:0 color sampling images, RGB images have the high correlation in inter-color planes. Using this characteristic, some methods which are contributed in JCT-VC standardization meetings estimate the pixel values of inter-color plane. But when we use the estimation of inter-color plane in RGB images, high frequency components of RGB images are caused to reduce the coding efficiency because they usually have the low inter-color plane correlation. Therefore, in this paper, we propose an adaptive low pass filtering method in the inter-color plane estimation. Using this method, we can improve the estimation efficiency of inter-color plane in RGB images. The experimental results with HEVC RExt RGB test sequences show that the proposed method has 0.6% BD(Bjontegaard Distortion)-rate gain and some increased complexity compared to the previous inter-color plane estimation method.

• Composites Research
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• v.29 no.5
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• pp.249-255
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• 2016

The fiber metal laminates have been widely used at aerospace industry due to outstanding fatigue characteristic, corrosion resistance and impact resistance and so forth. The objective of this research is to establish the proper manufacturing variables for enhancing the interfacial energy release rate of fiber metal laminates using Taguchi method. The major variables of the manufacturing process are surface treatment, pre-specified temperature holding time and additional pressure. In order to determine the interfacial adhesive strength, the double cantilever beam and end-notched flexure tests were conducted. Afterward, Mode I and II energy release rates at various conditions were introduced signal-to-noise ratio with respect to each condition. Finally, the most efficient manufacturing variables are recognized using larger-the-better characteristic.

• Natural Product Sciences
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• v.5 no.1
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• pp.25-32
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• 1999

The pharmacological actions of ambrein were investigated alone or in combination as a pretreatment with agonists (adrenaline, noradrenaline, acetylcholine, histamine, nicotine), antagonists (atropine, atenolol) and calcium channel blocker (verapamil) in vivo in anaesthetized SWR rats using blood pressure, heart rate and myocardial contractility as parameters. Ambrein in the dose range of 50-200 mg/kg to the normotensive anaesthetized rats demonstrated negative chronotropic effect and increased the myocardial contractility significantly. At the mid dose (100 mg/kg) this increase in contractile force was 36% and 44% above the normal at 30 min and 60 min intervals post-treatment, respectively. Both of the lower and high doses (50 mg/kg and 200 mg/kg) had similar effects. Furthermore, this contractile response was dose related. Also, this compound produced a considerable increase in myocardial contractility when used as a pretreatment with some agonists and antagonists. The results on blood pressure did not show a considerable change when ambrein was used alone. However, ambrein pretreatment at the dose of 100 mg/kg did not block the effects of adrenaline, noradrenaline, isoprenaline and acetylcholine on heart rate and blood pressure. On the other hand, this pretreatment attenuated the sympathoadrenal effects of nicotine significantly. Chronotropic and blood pressure changes produced by histamine were also inhibited by ambrein pretreatment. This pretreatment significantly reversed the effects of atenolol but failed to demonstrate any change in the negative chronotropic, inotropic and hypotensive responses induced by verapamil. It is concluded that ambrein induced nonselective dose dependent antagonism of the effects of some agonists and antagonists require contribution of some neuromediators. However, the positive isotropic effects of ambrein possibly involve the enhancement of slow Ca channels and/or activation of ${\beta}-adrenergic$ receptors in the heart. At this moment it is difficult to explain the exact mode of action of ambrein and the studies dealing with Ca channel blocker and adrenergic blocker followed by ambrein may help to define the factors which contribute to its positive inotropic effects.

• Journal of the Korean Vacuum Society
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• v.7 no.2
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• pp.118-126
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• 1998

A study to improve filling of semiconductor contact holes by enhancement of the directionality of the source beams has been undertaken. The collimation of source beams was improved by the ionized cluster beam deposition technique with modification of the cell geometry. The collimation tested with neutral beam was excellent. But, the Cu flims were grown in a columnar mode due to the lack of surface mobilit of the impinged clusters. A shadow effect also caused cleavage and consequent discontinuity at the steos as films grow. By applying acceleration voltage, the columnar growth in a contact hole of 0.5 $\mu$m diameter and 1 $\mu$m height disappeared and considerable coverage at the side wall of the contacts as well as perfect bottom coverage were observed. These are all due to the assistants of the accelerated ionized clusters with high kinetic energy. Thus we demonstrated that the ICB deposition technique can be used to completely fill sub-half-micron contact holes with high aspect ratio.