• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.551-553
• /
• 2005

When a hearing aid' s user is listening through telephone or cellular phone, he/she usually suffers from severe electrical magnetic interference noise. It is because hearing aids amplify voice signal as well as background noise. A telecoil, an induction coil, is a possible solution for the problem. Because a telecoil has the characteristic of high pass filter, it has some problem of resulting increased high frequency noise. For solving this problem, we can use a capacitor connected with the telecoil in parallel. According to capacitance, receiving signal quality may change. In this paper, proper capacitor values for the best sound quality are investigated by experimental work.

• Current Optics and Photonics
• /
• v.3 no.6
• /
• pp.548-554
• /
• 2019

A binary encoding method for grayscale images is proposed to address their unsatisfactory decryption results from joint transform correlator (JTC) encryption systems. The method converts the encryption and decryption of grayscale images into that of binary images, and effectively improves decrypted-image quality. In the simulation, we replaced unencoded grayscale images with their binary encoded counterparts in the JTC encryption and decryption processes, then adopted a median filter to suppress saturation noise while keeping other settings unchanged. Accordingly, decrypted-image quality was clearly enhanced as the correlation coefficient (CC) between a decrypted image and its original rose from 0.8237 to 0.9473 initially, and then further to 0.9937, following the above two steps respectively. Finally, optical experimental results confirmed that the proposed encryption system works correctly.

• Textile Coloration and Finishing
• /
• v.10 no.4
• /
• pp.45-52
• /
• 1998

Reuse of wastewater become an important consideration to solve the environmental pollution problems in recent industriallzation and urbanization. Especially, he characteristic of dyeing process is subject to use much water and thus has serious problems for removal of color and organic pollutants in their wastewater. This report is divided into two main parts ： The purpose of the first part was to determine if alkaline wastewater discharged from textile dyeing operation factory could be flocculated directly by Fenton oxidation method. This study was conducted to investigate Fenton reagent dose and reaction condition of Fenton method as pretreatment for dyeing wastewater in K dyeing industry were investigated. In the second part of this research, to treat dyeing wastewater it was found that the most effective way is to use ultrafiltation and reverse osmosis at the conditions of the pH 7.0~8.0 and operating pressure of $2.5~35kg_f/cm^2$. This paper is mainly dealt with the application on reuse system of dyeing wastewater treatment using ultrafiltration and reverse osmosis membranes. The results showed that dyeing wastewater could be reused by chemical, filter and membrane sequential treatment process.

• Proceedings of the IEEK Conference
• /
• 2001.06e
• /
• pp.89-92
• /
• 2001

For the diagnosis of arrhythmia in the heart system, the QRS complex of ECG signals is used in many cases. The rejection of the noise in ECG signals is important to acquisition of exact QRS complex. This paper presents some experimental results about instantaneous bandwidth estimation and noise rejection of ECG signals with the purpose of rejection of the 60 Hz power noise and the motion artifacts such as EMG signals and contact noise. ECG signals corrupted by noise are cleaned by using the variable bandwidth filter. For the filtering of ECG signals with noise, the instantaneous bandwidth of the signals is estimated by analysis of time-frequency representation of ECG signal.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.265-270
• /
• 2006

Recently, inertial sensors like gyros and accelerometers have been quite miniaturized by Micro Electro-Mechanical Systems (MEMS) technology. JAXA is developing a MEM-based GPS/INS hybrid navigation system named Micro-GAIA. The navigation performance of Micro-GAIA was evaluated through off-line analysis by using flight test data. The estimation errors of the roll, pitch, and azimuth were $0.03^{\circ}$, $0.05^{\circ}$, $0.05^{\circ}$ $(1{\sigma})$, respectively. he horizontal position errors after 60-second GPS outages were reduced to 25 m CEP. The attitude errors and position errors are nearly half of ones reported previously[2]. Furthermore, using the adaptive Kalman filters, the robustness against the uncertainty of the measurement noise was improved. Comparing the innovation-based and residual-based adaptive Kalman filters, it was confirmed that the latter is robuster than the former.

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.736-738
• /
• 1993

The problems of he plentiful harmonics and low power factor have occured to the increase of semiconductor power conversion equipments. These problems should be improved by the active power filters which have been studied recently. This paper described the appliaction of delta modulation technique to current-fed filter and control performance. Through digital simulation the output characteristics of delta modulator are investigated theoretically.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.5
• /
• pp.974-980
• /
• 1997

The 23GHz 1-state LNA was designed by using MPIE numerical analysis and conventional design EEsof softwares. The circuit was designed using conventional tools but analyzed and modified by using numerical MPIE tools. he matching sections was designed with parallel coupled filter-type, which gives impedance matching and DC blocking and has small discontinuities. THe FET chip is directly attached to the graound metal. The designed LNA gives 5.8dB gain and 2.5dB noise figure withoug considering the loss and impedance shift of connectors that degenerate the gain and noise figure considerably. this results gives very promising characteristics for our design process and matching schemes and fabrication technologies.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.104.2-104.2
• /
• 2013

A residual gas analyzer (RGA) system has been developed in this laboratory. Characteristics of the RGA system parts such as ion source, quadrupole mass filter and sensitivity are introduced. Some efforts have been made to improve performance of the two types of ion sources, open ion source (OIS) and closed ion source (CIS). A metal mesh was placed onto the electron beam entrance of the CIS anode tube to block the filament field penetration. Sensitivity of the CIS ion sources with and without the mesh was compared by mass spectra of SF6 gas (97% He base) introduced into the CIS anode through a needle valve. About ten-times improvement in the RGA sensitivity was observed for the CIS with the mesh in the electron entrance. Computer simulation showed an axi-symmetric anode potential distribution and improved focusing of the electron beam inside the anode tube with the mesh.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.4
• /
• pp.2113-2128
• /
• 2019

Image thresholding techniques introducing spatial information are widely used image segmentation. Some methods are used to calculate the optimal threshold by building a specific histogram with different parameters, such as gray value of pixel, average gray value and gradient-magnitude, etc. However, these methods still have some limitations. In this paper, an entropic thresholding method based on Gabor histogram (a new 2D histogram constructed by using Gabor filter) is applied to image segmentation, which can distinguish foreground/background, edge and noise of image effectively. Comparing with some methods, including 2D-KSW, GLSC-KSW, 2D-D-KSW and GLGM-KSW, the proposed method, tested on 10 realistic images for segmentation, presents a higher effectiveness and robustness.

• Current Optics and Photonics
• /
• v.4 no.6
• /
• pp.530-539
• /
• 2020

Hyperspectral images feature a relatively narrow band and are easily disturbed by noise. Accurate estimation of the types and parameters of noise in hyperspectral images can provide prior knowledge for subsequent image processing. Existing hyperspectral-noise estimation methods often pay more attention to the use of spectral information while ignoring the spatial information of hyperspectral images. To evaluate the noise in hyperspectral images more accurately, we have proposed a spectral-spatial cooperative noise-evaluation method. First, the feature of spatial information was extracted by Gabor-filter and K-means algorithms. Then, texture edges were extracted by the Otsu threshold algorithm, and homogeneous image blocks were automatically separated. After that, signal and noise values for each pixel in homogeneous blocks were split with a multiple-linear-regression model. By experiments with both simulated and real hyperspectral images, the proposed method was demonstrated to be effective and accurate, and the composition of the hyperspectral image was verified.