• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.237-244
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• 2022

We measured the clutter loss (CL) and building entry loss (BEL) of signals in a low-rise high-density suburban environment. Three propagation models for BEL, CL, and a combination of BEL and CL were measured in the selected environment. We then derived the figures when the BEL was combined with the CL. At the two frequencies, the measured value of combination of BEL and CL is 27.55 dB and 26.12dB, respectively, and the differences between the measured value and the sum were -4.19 dB and 5.82 dB. Considering that the measurement was performed inside a building, such a difference seems to be small. Therefore, when BEL and CL were measured separately and summed, and then combined and summed, differences of -4.19 dB and 5.82 dB were apparent. This this result can be referenced when similar case of a propagation model was analyzed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.9-14
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• 2008

Intentional city bands and public radio frequencies could reduce the internet transmission speed on the wired lines because AM and HF band are overlapping on the xDSL up and down data steam by way of the wired transmission lines. We were designed the adaptive common mode rejection circuit with 2 way amplifier against public radio frequency. Specially our circuits were applied for power and signal lines. We could reduced the common mode rejection up to 30dB and increased the up stream speed around 1.8 times using a our developed equipments. Also it could expanded the transmission distance up to 1.7 times than old lines.

• Journal of Families and Better Life
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• v.26 no.4
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• pp.149-162
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• 2008

The purpose of this study is to provide a meaningful thought to professionals and administrators of Korea working for Consumer General Education development at their Universities. Also, tips for organizing and meaning Consumer General Education Curriculum effectively are provided. Finally, the study suggests essential elements to improve qualities of Consumer General Education in Korea Universities. This study's method are content analysis through web site and survey. The subjects of this survey were 257 students. The data were collected by qusetionaires developed by researcher and analyzed by frequencies, correlation Analysis, One Way Anova, Duncan Test, Factor Analysis, Multiple Regression Analysis. The major findings were as follows: University students's satisfaction level about General Education was low and the needs level about Consumer General Education was high. And the education service quality showed factors to be administrative service element, professor service element, classroom environment element, communication element. And Multiple Regression Analysis on each of the education service quality factors had been significant effects for find out the differences in the degree of satisfaction.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.27-31
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• 2017

A high-performance wideband transition from double-sided parallel-stripline (DSPSL) to coplanar stripline (CPS) is proposed. This transition is designed by consideration of gradual field transformation and optimal impedance matching between DSPSL and CPS. Clear design guidelines of proposed transition are provided to determine the ground shape and the transition length. The fabricated transition exhibits less than 0.7 dB insertion loss per transition for frequencies from 6.2 to 18.2 GHz, and less than 1.25 dB insertion loss to over 30 GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.7
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• pp.987-994
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• 2013

In this paper, a dual-band open-ended circular ring moNopole antenna for WLAN(Wireless Local Area Networks) applications. The proposed antenna is based on a planar moNopole design, and composed of open-ended one circular ring of radiating patches for dual-band operation. To obtain the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS) and found the parameters that effect antenna characteristics. Using the obtained parameters, the proposed antenna is fabricated. The fabricated antenna is measured at the operating frequencies(2.4-2.484 GHz, 5.15-5.825 GHz), and the return loss coefficient, gain, and radiation patterns are determined.

• International journal of advanced smart convergence
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• v.8 no.4
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• pp.214-220
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• 2019

Hearing impaired people are apt to be in danger because they can't detect danger with sound. Hearing impaired people have less risk-detection ability than non-disabled people because of lack of hearing. There are many devices to help the hearing impaired, such as hearing aids. A hearing aids can be helpful, but it may not be available depending on the degree or type of hearing loss for example, to the hearing-impaired people with little remaining hearing of high frequencies, ordinary hearing aids are not very useful for understanding the high frequency consonants and it requires a high cost, from thousands to tens of thousands of dollars. Also, it is difficult for the underprivileged, such as the low-income bracket and the elderly, to use them because they are difficult to manage. Therefore, this paper describes the development of low-cost wearable device to assistant a hearing-impaired people using Arduino. Also, it accepts values from switches or sensors and can control external electronic devices such as LEDs and motors to create objects that can interact with the environment. In this is paper, through sound sensors, the ambient sound was taken as an analogue value and transmitted to the aduino board, and the vibration motor was operated when the noise was generated, so that the user could be aware of the occurrence of danger.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.64-67
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• 1997

In the total artificial heart(TAH), a transcutaneous information transmission system(TITS) is vely important to monitor the TAH status and detect the device failure, and repair the possible problems. First of all, the communication channel(skin) and method were simulated in terms of transmittance, scattering, reflection and absorption, then the system was designed with size reduction including low power consumption and reliability compared to the previous one. The informations are transmitted through the skin(approximately 1cm in depth) by frequency modulated near infrared(NIR) pulses using 780nm laser diodes as transmitters and photodiode as receiver with high speed and high spectral sensitivity. The logic high and low frequencies are 3MHz, 1MHz respectively. The system is a bidirectional data link for more than 38.4Kbps data rate, full-duplex with a bit error rate of less than $10^{-5}$.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3181-3183
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• 2000

As the fact that the simple data of text and sound in early year have been changed to be high quality images and sounds. PLL(Phase-Locked Loop) system plays an important role in communication system. VCO(Voltage Controlled Oscillator) is the most important part in PLL system because it can have critical effects on operation of PLL. Recently, it has been raised the necessity of high speed and high accuracy circuit application. In this paper, a new differential voltage clamped VCO using negative-skewed path is suggested. Using a dual-delay scheme to implement the VCO, higher operation frequency and wider tuning are achieved simultaneously. The dual-delay scheme means that both the negative skewed delay paths and the normal delay paths exist in the same ring oscillator. The negative skewed delay paths decrease the unit delay time of the ring oscillator below the single inverter delay time. As a result, higher operation frequency can be obtained. The whole characteristics of VCO are simulated by using HSPICE. Simulation results show that the resulting operating frequencies are 50% higher than those obtainable from the conventional approaches.

• International Journal of Contents
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• v.5 no.2
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• pp.26-31
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• 2009

This paper describes a new image watermarking scheme invariant to rotation, scaling and translation (RST) attacks. For obtaining the invariance properties we propose to present an image of watermark by wedges and rings to convert its rotation to shift and then utilize the shift invariance property of the Direct Fourier Transform (DFT). But in contrast to conversional schemes based on the Fourier-Mellin transform (FMT), we do not use a log-polar mapping (LPM). As a result, our scheme preserves high quality of original image since it is not underwent to LPM For withstanding against JPEG compression, noise addition and low-pass (LP) filtering attacks a low frequency watermark is embedded into middle frequencies of the original image. Experiments with various attacks show the robustness of the proposed scheme.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.04a
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• pp.25-28
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• 1984

This paper describes the design of band-pass filter using the dielectric resonator and microstrip line depends mainly upon the magnetic field and is principal parameter as band-pass filter. Because dielectric resonator band~pass filter has a very high-Q, the bandwidth of this filter is very narrow. as a result of experiment, the dielectric resonator bandwidth of this filter is very narrow. As a result of experiment, the dielectric resonator band-pase filter has various modes central frequencies due to the mode change and good characteristric as a band-pass filter.