• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.93-99
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• 2024

The digital medical imaging, especially, computed tomography (CT), should necessarily be considered in terms of noise distribution caused by converting to X-ray photon to digital imaging signal. Recently, the denoising technique based on deep learning architecture is increasingly used in the medical imaging field. Here, we evaluated noise reduction effect according to various noise types based on the U-net deep learning model in the lung CT images. The input data for deep learning was generated by applying Gaussian noise, Poisson noise, salt and pepper noise and speckle noise from the ground truth (GT) image. In particular, two types of Gaussian noise input data were applied with standard deviation values of 30 and 50. There are applied hyper-parameters, which were Adam as optimizer function, 100 as epochs, and 0.0001 as learning rate, respectively. To analyze the quantitative values, the mean square error (MSE), the peak signal to noise ratio (PSNR) and coefficient of variation (COV) were calculated. According to the results, it was confirmed that the U-net model was effective for noise reduction all of the set conditions in this study. Especially, it showed the best performance in Gaussian noise.

• Journal of Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.101-114
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• 2006

Recently due to the increase of cars and city life, the traffic congestion has worsened. It Is particularly worse in the center of the metropolis. Within the general public means, the public transport buses have the advantage of being more cheap, accessible and mobile. But as there is no separate lane for buses, the collision of cars and buses are creating damage to public service. In order to solve this situation, the bus priority signal system has been introduced to reduce the bus travel time and improve its services. The purpose of this study is to establish bus priority signal algorithm which builds bus efficiency under the real-time traffic signal control system and to analyze the effect of it. As the green time was calculated against real time (under the real-time traffic signal control system), compared to existing bus priority signal there was a reduction in cross street loss. The modified cycle was used to maintain signal progression. A case study was carried out using VISSIM simulation model. In result of this study, we found that there was a decrease in bus travel time despite some evidence of car delays and compared to existing bus priority signal the delay of dishonor could be reduced dramatically. The analysed result of person delay using MOE, is that there is evidence that when bus priority signal is in effect, the person delay is reduced.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.17-28
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• 2009

There are many limitations in dealing with rapidly changing traffic demand in urban cities. Thus recently, traffic operation and management skills are more emphasized rather than the expansion of traffic facilities. In particular, in the interrupted flow formed by signalized intersections, it is quite important to give optimal signal timing to each intersection with consideration of progression. However, as fixed signal times per direction can affect passing capacity in signalized intersections, the present four-signal phase including a left-turn signal has many limitations, including reduction of directional road capacity when traffic demand is increases dramatically during peak hours. Because of this problem, lots of studies about internal metering techniques for oversaturated signal control skills have progressed but these techniques are not used widely due to the absence of detectors for queue sensing in real-time signal control systems. In this research, a new methodology called the "restrictive left-turn signal control", which is already used at the intersection above Samsung subway station, is suggested in order to reduce control delay of urban arterial roads. The restrictive left-turn signal control allows a driver to make a U-turn and then a right turn instead of turning left in that intersection. With this change, the restrictive left-turn signal control can contribute to increased intersection capacity by reducing the number of signal phases and maximizing the through phase time. However, road structure and traffic conditions at the target intersections should be considered before the adoption of the proposed signal control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.9C
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• pp.888-894
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• 2007

The computational complexity of a sphere decoder (SD) is conventionally reduced by decoding order scheme which sorts candidate symbols in the ascending order of the Euclidean distance from the output of a zero-forcing (ZF) receiver. However, since the ZF output may not be a reliable sorting reference, we propose two types of sorting schemes to allow faster decoding. The first is to use the newly found lattice points in the previous search round instead of the ZF output (Type I). Since these lattice points are closer to the received signal than the ZF output, they can serve as a more reliable sorting reference for finding the maximum likelihood (ML) solution. The second sorting scheme is to sort candidate symbols in descending order according to the number of candidate symbols in the following layer, which are called child symbols (Type II). These two proposed sorting schemes can be combined with layer sorting for more complexity reduction. Through simulation, the Type I and Type II sorting schemes were found to provide 12% and 20% complexity reduction respectively over conventional sorting schemes. When they are combined with layer sorting, Type I and Type II provide an additional 10-15% complexity reduction while maintaining detection performance.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.667-672
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• 2013

This paper presents the development of a condition monitoring system that monitors the operating conditions of a reduction unit, such as the bearing temperature, gearbox vibration, and gear oil deterioration, and notifies the operator of potential problems or abnormal conditions. A series of field tests on high-speed rail and conventional lines was performed to identify the characteristics of temperature rise and vibration levels on the reduction unit during operation. The monitoring system was designed based on the proper sensor selection, measurement method, and signal analysis to optimize the interface with the operating system of high-speed trains. Application of this monitoring system to high-speed trains will play an important role in their proper maintenance and safe operation.

• Communications for Statistical Applications and Methods
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• v.19 no.2
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• pp.225-235
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• 2012

Noise reduction is an important issue in the field of image processing because image noise worsens the quality of the input image. The basic difficulty is that the noise and the signal are not easy to distinguish. Simple moothing is one of the most basic and important procedures to remove the noise, however, it does not consider the level of noise. This method effectively reduces the noise but the feature area is simultaneously blurred. This paper considers the block approach to detect noise and image features of the input image so that noise reduction could be adaptively applied. Simulation results show that the proposed algorithm improves the overall quality of the image by removing the noise according to the noise level.

• Smart Media Journal
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• v.3 no.1
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• pp.39-45
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• 2014

The partial product matrix of a parallel squarer are symmetric about the diagonal. To reduce the number of partial product bits and the depth of partial product matrix, it can be typically folded, shifted and bit-rearranged. In this paper, an efficient design approach for the combined squarer, capable of operating on either unsigned or signed numbers based on a mode selection signal, is presented. By simulations, it is shown that the proposed combined squarers lead to up to 18% reduction in area, 11% reduction in propagation delay and 9% reduction in power consumption compared with the previous combined squarers.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.75-81
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• 2015

In active sonar system, clutters degrade performance of target detection/tracking and overwhelm sonar operators in ASW (Antisubmarine Warfare). Conventional clutter reduction algorithms using consistency of local peaks are studied in multi-ping data and tracking filter research for active sonar was conducted. However these algorithms cannot classify target and clutters in single ping data. This paper suggests a single ping clutter reduction approach to reduce clutters in mid-frequency active sonar system using echo shape features. The algorithm performance test is conducted using real sea-trial data in heavy clutter density environment. It is confirmed that the number of clutters was reduced by about 80 % over the conventional algorithm while retaining the detection of target.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1756-1760
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• 2015

This paper focuses on a priori signal to noise ratio (SNR) estimation method for the speech enhancement. There are many researches for speech enhancement with several ambient noise cancellation methods. The method based on spectral subtraction (SS) which is widely used in noise reduction has a trade-off between the performance and the distortion of the signals. So the need of adaptive method like an estimated a priori SNR being able to making a high performance and low distortion is increasing. The decision directed (DD) approach is used to determine a priori SNR in noisy speech signals. A priori SNR is estimated by using only the magnitude components and consequently follows a posteriori SNR with one frame delay. We propose a modified a priori SNR estimator and the weighted rational transfer function for speech enhancement with wind noises. The experimental result shows the performance of our proposed estimator is better Perceptual Evaluation of Speech Quality scores (PESQ, ITU-T P.862) compare to the conventional DD approach-based systems and different noise reduction methods.

• Journal of IKEEE
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• v.24 no.2
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• pp.649-653
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• 2020

GPS is a representative satellite navigation system that provides users with accurate location and time information. GPS L1 C / A is opened for civilian and thus utilized in various fields. When the satellite signal reaches the receiver, signal acquisition unit of the digital signal processing hardware searches and acquires the signal among visible satellites. The signal acquisition unit has different implementation methods depending on the signal searching method, such as serial search acquisition, parallel frequency search, parallel code phase search. In this paper, we compare and analyze the three representative acquisition hardwares using live GPS L1 C/A signals. According to the comparison, the parallel code phase search acquisition outperforms the other methods due to reduction of the number of the searchings and a high resolution.