• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.12
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• pp.1551-1557
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• 2019

In modern society, a variety of video media have been widely spread in line with the fourth industrial revolution and the development of IoT technology; in accordance with this trend, numerous researches have been performed to remove noise generated in image and data communications. However, the conventional Additive White Gaussian Noise (AWGN) cancellation techniques are likely to induce a blurring phenomenon in the noise removal process, thus impairing the information of the image. In this study, we propose an algorithm for minimizing the loss of image information in the removal process of AWGN. The proposed algorithm can apply weights according to the characteristics of noise by predicting AWGN in the image, where the output is calculated based on adding and subtracting the outputs of the high pass filter and the low pass filter. Compared to the existing method, the noise reduction using the proposed algorithm exhibited less blurring issues and better noise reduction properties in the AWGN removal process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1060-1065
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• 2007

This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.4
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• pp.333-338
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• 2011

This paper describes the design process of floor damping material optimization to reduce structure borne noise. This process uses finite element analysis(FEA) along with experimental techniques to complement each other. The objective of this approach was to develop an optimized damping material application layout and thickness at the initial design stage. The first step is to find the sensitivity areas of vehicle body without damping material applied using FEA. In order to determine the high vibration areas of the floor panel, the velocity was measured using a scanning laser vibrometer from 20 Hz to 300 Hz. To excite the floor panel vibration, shaker was placed at the front suspension attachment point. The second step is the optimization process to determine the light weight solution of damping material. The design guideline of damping material was suggested that the lightweight solution was verified using test result of road noise. Design engineer could efficiently decide the design variable of damping material using parameter analysis results in early design stage.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.10
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• pp.24-30
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• 2020

The high speed of an engine balance box may cause significant additional gear noise. Gear accuracy is the most useful key to reduce gear noise, but the small tooth width and thin-walled anti-backlash gear introduce challenges to the manufacturing process. In order to reduce the gear noise caused by gear pitch error, this paper investigates the correlation between influencing factors and gear pitch error by analyzing the processing technology, tooling fixture, and equipment accuracy. By improving the process and optimizing the gear design, the gear machining accuracy was improved and the processing cost was saved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.899-903
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• 2008

The purpose of this study is to establish the noise abatement procedures in Kimhae International Airport and also make noise limit and methods to monitor and detect an aircraft flying over Kimhae airport. First of all, noise monitoring system(NMS) should be set up, have a test and noise limit will be adjusted afterwards. Before applying Noise Abatement Procederes and noise limit, the amendment of Aviation Law 'article 108' required to proceed. The accumulative data and long term process of NMS will proceed and it is necessary to issue a notification of noise limit in phases.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.1
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• pp.74-82
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• 2008

The objective of this paper is to remove noises of image based on the heuristic noises filter and to extract a tumor region by using morphology techniques in breast ultrasound image. Similar objective studies have been conducted based on ultrasound image of high resolution. As a result, efficiency of noise removal is not fine enough for low resolution image. Moreover, when ultrasound image has multiple tumors, the extraction of ROI (Region Of Interest) is not accomplished or processed by a manual selection. In this paper, our method is done 4 kinds of process for noises removal and the extraction of ROI for solving problems of restrictive automated segmentation. First process is that pixel value is acquired as matrix type. Second process is a image preprocessing phase that is aimed to maximize a contrast of image and prevent a leak of personal information. In next process, the heuristic noise filter that is based on opinion of medical specialist is applied to remove noises. The last process is to extract a tumor region by using morphology techniques. As a result, the noise is effectively eliminated in all images and a extraction of tumor regions is possible though one ultrasound image has several tumors.

• Journal of Korea Water Resources Association
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• v.52 no.9
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• pp.603-613
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• 2019

This study proposes a method to generate runoff ensemble members using a rainfall-runoff model based on the shot noise process (hereafter the rainfall-runoff model). The proposed method was applied to generate runoff ensemble members for three drainage basins of Daerim 2, Guro 1 and the Jungdong, whose results were then compared with the observed. The parameters of the rainfall-runoff model were estimated using the empirical formulas like the Kerby, Kraven II and Russel, also the concept of modified rational formula. Gamma and exponential distributions were used to generate random numbers of the parameters of the rainfall-runoff model. Especially, the gamma distribution is found to be useful to generate various random numbers depending on the pre-assigned relationship between mean and standard deviation. Comparison between the generated runoff ensemble members and the observed shows that those runoff ensemble members generated using the gamma distribution with its standard deviation twice of the mean properly cover the observed runoff.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.281-284
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• 2015

Digital image processing is utilized in various application fields by rapid development of memory cell. However, the noise occurs with various causes in the process of data processing process and various methods have been studied in order to remove such noises. In general, the image is damaged by the mixed noise which has different characteristics each other. This paper proposed a filter algorithm which processes the data according to shape of noise in order to mitigate the impact of the mixed noise added to the image. In addition, this paper compared this filter algorithm with the current methods and used PSNR(peak signal to noise ratio) as a criterion of judgment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.676-678
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• 2016

Noise occurs in the process of obtaining, transmission, and processing in image processing systems and these noises lower the resolution of image and cause visual errors. Currently, a representative filter to remove salt and pepper noise is SMF(standard median filter) but it is inadequate in preserving edge as the noise field expands. Therefore, for salt and pepper noise enviroment, the study suggested and algorithm that are places with original pixel when the central pixel is non-noise and process by applying weighted value on areas with less local mask pixel changes when there is noise.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.1-10
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• 2021

Gears, which rotate and transmit power by interlocking two cogwheels, were invented in BC. They have been used in various systems, including industrial machinery, transportation devices, and living facilities, through the industrial revolution. Regardless of how they are used, gears are a major source of noise and vibration. Many effective measures are being taken to reduce the radiation noise generated from gears, most commonly by lubrication. Lubrication in gear units reduces friction on interlocking gear surfaces, dampening radioactive noise. This can be very useful for quiet gear design if these lubricating damping effects can be reflected in the analytical phase for gear design. This study experimentally confirms the properties of lubricated and non-lubricated radioactive noise by designing a decelerator gearbox and analyzing the radioactive noise characteristics by torque, rotation, and the number of gears using computer analysis.