• Journal of Convergence for Information Technology
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• v.7 no.3
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• pp.97-103
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• 2017

In this paper, we aim to investigate the generalization of ZRC codes by performing performance analysis on various coding rates and channel conditions of Zero Reduction Code (ZRC) for dimming control in VLC system. Simulation results show that the ZRC codes with relatively high coding rate achieve the enhanced BER performance as the RMS (Root Mean Square) delay spread value increases in the NLOS channelse. Therefore, it is expected that the designing of the dimming control technology using ZRC in the future visible light communication system will help to determine the coding rate according to the channel state through the analysis result in this study.

• Journal of the Korea Convergence Society
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• v.9 no.9
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• pp.47-52
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• 2018

Wi-Fi enabled Internet of Things (IoTs) had a substantial impact on society, economy and industry. However wireless connectivity technologies in unlicensed band such as Wi-Fi are vulnerable to interferences. They also face difficulty providing wireless connectivity over long range in dense networks due to the dynamically changed interference effect and asymmetric interference conditions. In this paper, robust acknowledgement transmission scheme is proposed for long range IoTs. According to the proposed scheme, it is possible to control the transmission rate of the transmission success rate of the response frame by adjusting the transmission rate of the response frame when the interference is present asymmetrically. It is also possible to use higher data rate when high quality link is guaranteed. The evaluation results demonstrated the proposed scheme improves the aggregate throughput by at most 9 Mbps when 20 MHz bandwidth transmission mode was adopted.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.94-97
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• 2003

In this Paper, propose for MLP(multilayer perception) neural network that uses optimization recognition training scheme for the wavelet transform and the numeral image add to noise, and apply this system in Numeral Recognition. As important part of original image information preserves maximum using the wavelet transform, node number of neural network and the loaming convergence time did size of input vector so that decrease. Apply in training vector, examine about change of the recognition rate as optimization recognition training scheme raises noise of data gradually. We used original image and original image added 0, 10, 20, 30, 40, 50㏈ noise (or the increase of numeral recognition rate. In case of test image added 30∼50㏈, numeral recognition rate between the original image and image added noise for training Is a little But, in case of test image added 0∼20㏈ noise, the image added 0, 10, 20, 30, 40 , 50㏈ noise is used training. Then numeral recognition rate improved 9 percent.

• Composites Research
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• v.35 no.1
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• pp.38-41
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• 2022

In this study, the strain rate dependent tensile and compressive properties of PP-LGF and TPO was investigated under the high strain rate by using the Split Hopkinson Pressure Bar (SHPB). The SHPB is the most widely used apparatus to characterize dynamic mechanical behavior of materials at high strain rates between 100 s^-1 and 10,000 s^-1. The SHPB test is based on the wave propagation theory which was developed to give the stress, strain and strain rate in the specimen using the strains measured in the incident and transmission bars. In addition, to verify the strain data obtained from SHPB, the specimen was photographed with a high-speed camera and compared with the strain data obtained through the Digital Image Correlation (DIC).

• ETRI Journal
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• v.30 no.2
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• pp.261-267
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• 2008

In this paper, we propose and demonstrate a cost-effective technique to upgrade the capacity of dense wavelength division multiplexing (DWDM) networks to a 40 Gb/s line rate using the existing 10 Gb/s-based infrastructure. To accommodate 40 Gb/s over the link optimized for 10 Gb/s, we propose applying a combination of super-FEC, carrier-suppressed return-to-zero, and pre-emphasis to the 40 Gb/s transponder. The transmission of 40 Gb/s DWDM channels over existing 10 Gb/s line-rate long-haul DWDM links, including $40{\times}40$ Gb/s transmission over KT's standard single-mode fiber optimized for 10 Gb/s achieves successful results. The proposed upgrading technique allows the Q-value margin for a 40 Gb/s line rate to be compatible with that of 10 Gb/s.

• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.54-60
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• 2016

In this study, tank truck incidents of road transport of hazardous materials to experimental investigated the potential fire hazard. Real scale fire was to perform experiments for on this qualitative and quantitative data collection and analysis. Particularly affected by radiant heat from the flames caused and damage estimates range investigated accordingly. Flame temperature, internal temperature of tank and emitted radiation from the flames was investigated. The flame of light oil spill caused a fire at a temperature of about $300^{\circ}C$ high in comparison with the methanol by combustion of diesel and methanol, according to the difference, the flame duration changes varies depending on the Burning rate. Depending on spill rate(30, 60, 90 and $120{\ell}/min$) and the longer the duration of the flame important factors for the internal temperature of tank lorry rise was found. Road accident in a fire caused by leakage of hazardous was could the higher the damaged. Therefor, Fire suppression activities should be required in particular to be around.

• Journal of Korea Multimedia Society
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• v.19 no.7
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• pp.1107-1115
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• 2016

Efficient Market Hypothesis (EMH), states that at any point in time in a liquid market security prices fully reflect all available information. This paper presents a study of proving the hypothesis through daily Twitter sentiments using the hybrid approach of the lexicon-based approach and the naïve Bayes classifier. In this research we analyze the currency exchange rate movement of Indonesia Rupiah vs US dollar as a way of testing the Efficient Market Hypothesis. In order to find a correlation between the prediction sentiments from Twitter data and the actual currency exchange rate trends we collect Twitter data every day and compute the overall sentiment to label them as positive or negative. Experimental results have shown 69% correct prediction of sentiment analysis and 65.7% correlation with positive sentiments. This implies that EMH is semi-strong Efficient Market Hypothesis, and that public information provide by Twitter sentiment correlate with changes in the exchange market trends.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.2
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• pp.69-78
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• 2009

Dust in the fabric production sites is increased by the static electricity in air which is generated in the manufacturing process. The static electricity is shown in inverse proportion to humidity of the production sites. The optimum humidity rate for the filament in the production process has been established as 65~75%. Where as, average humidity rate of production site is estimated as 40%. Therefore, it is necessary to raise the humidity rate by 30% to maintain appropriate humidity to control generation of static electricity and dust in the production sites. In this study, a new air-jet water sprayer was developed and it can produce $10{\mu}m$ sprayed particles. When the air-jet water sprayer was operated on the production site dust generation rate was shown far below the environmental standard. It is assumed that when the air jet sprayers was applied to 1,000 fabric machines of 5 gloves making plants, its productivity and rates of operation will be improved by value of about 2.5 billion Won a year.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.226-231
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• 2010

This paper proposes a new coding technique for constructing error correcting high rate DC-free multimode code using a generator matrix generated from a sparse parity-check matrix. The scheme exploits high rate generator matrixes for producing distinct candidate codewords. The decoding complexity depends on whether the syndrome of the received codeword is zero or not. If the syndrome is zero, the decoding is simply performed by expurgating the redundant bits of the received codeword. Otherwise, the decoding is performed by a sum-product algorithm. The performance of the proposed scheme can achieve a reasonable DC-suppression and a low bit error rate.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.605-613
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• 2023

The multi-axis combined machining technology has enabled combined machining, which was difficult. However, the reality is that manufacturing costs are rising due to expensive equipment and there is a shortage of machine operation engineers. The purpose of this research is to present the optimum cutting conditions for the surface roughness when processing the inner diameter of SUS440C, which is an egg material, using a CNC automatic lathe. As a result of measuring the surface roughness, dry machining was the best at R_a0.481㎛ at a spindle speed of 4,000rpm, a feed rate of 0.05rev/min, and a cutting depth of 0.3mm. In wet machining, the highest value was R_a0.317 at a spindle speed of 2,000 rpm, a feed rate of 0.05 rev/min, and a cutting depth of 0.2 mm. The lower the feed rate, the better surface roughness appears. It was found that the feed rate had more influence than the number of revolutions and depth of cut.