• International Journal of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.1-10
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• 2018

In cognitive radio (CR), secondary users (SUs) are able to sense the absence of primary users (PUs) in the spectrum. Then, SUs use this information to opportunistically access the licensed spectrum in the PUs' absence. In this paper, we present an implementation of real-time video transmission with spectrum-sensing between two points using GNU Radio and a National Instruments 2900 Universal Software Radio Peripheral (USRP). In our project, spectrum-sensing is implemented at both transmitter and receiver. The transmitter senses the channel, and if the channel is free, a video signal (which could be a real-time signal from a video file) will be modulated and processed by GNU Radio and transmitted using a USRP. A USRP receiver also senses the channel, but in contrast, if the channel is busy, the signal is demodulated to reproduce the transmitted video signal. This project brings in several challenges, like spectrum-sensing in the devices' environment, and packets getting lost or corrupted over the air.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.6
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• pp.51-57
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• 1980

Any switching function can be constructed with universal building block of MAND gate. Threelevel AND-NOT logic networks with only true inputs are called TANT networks. Systematic approach to TANT minimization starts from the UF type minterm with the smallest subscript and ends when UF type minterms are all covered. Optinal PEI is composed of CPPI or EPPi without C-C table. The algorithm in this work is usful in solving TANT optimization porblem of four or five variables by hand solution. When variable are six or more, it is required to be solved by computer, A CAD software package of this algorithm with FORTRAN IV language is made to solve such problems.

• Journal of Distribution Science
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• v.13 no.4
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• pp.5-8
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• 2015

Purpose - The purpose of this paper is to review, analyze, and learn from the most recent cases of plagiarism and to identify and promote ethical practices in research and publication. Research design, data, and methodology - This is a case study, an analytical approach, which focuses on analyzing the most recent cases of plagiarism to identify ethical issues and concerns in journal publication practices. Results - Despite the availability of many software and web-based applications and programs to detect plagiarism, there is no universal or perfect plagiarism detection application available to ease the editorial responsibility. Lack of understanding the concept and ignorance of plagiarism were the main reasons for the cases of plagiarism. Conclusions - Some of the plagiarism cases reveal a lack of knowledge in proper application of in-text citations and references, including quoting, requiting, paraphrasing, and citing sources, etc. Furthermore, the need for recognizing and considering the distorted and falsified primary and secondary research data as plagiarism is essential to enhance ethical practices in journal publication.

• Journal of the Korean Institute of Landscape Architecture
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• v.24 no.3
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• pp.115-132
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• 1996

The purpose of this study is to estimate the soil loss amount with Geographic Information System according to the land use change of Buju mountain area in Mokpo city. To estimate the soil loss, Universal Soil Loss Equation which is the most proper technique to predict soil loss in this site condition is adopted and IDRISI, a raster GIS software, is used. GIS application with USLE is very efficient to estimate soil loss accurately and fastly. In order to decide value and to find application method of USLE factors, we used existing rainfall erosion index, soil erodibility analysis, slope length, slope steepness, vegetation management and practices, which are rated by GIS through the analysis of various studies related USLE. The result of this study was compared with the previous other researches to verify our method of constructing numerical data of USLE's factors. The result of verification of our way showed significance for the soil loss in forest area. But the result of verification for the soil loss in forest area. But the result of verification for the soil loss of cultivated area showed some errors. It seems that this result was due to local variation of topographical map.

• Journal of Engineering Education Research
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• v.5 no.2
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• pp.3-9
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• 2002

Recently, the use of the internet and the web becomes universal. So, many internet applications are made by educators. In this paper, contents about the electromagnetics course which is one of the basic subjects for electrical and electronic fields are dealt. Most textbooks concerned this topic describes the phenomena in mathematical formulas. Naturally, for the students, the understanding of the phenomena is not so easy. For the improvement the educational efficiency, the multimedia techniques such as HTML, pictures, animations and sound are utilized. And also the software developed by authors is available for the analysis or the exercise of various electromagnetic problems. The contents are composed 4 parts : electrostatic fields, magnetostatic fields, time varying fields propagation of waves.

• Journal of Engineering Education Research
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• v.5 no.1
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• pp.3-18
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• 2002

Recently, as the use of the Internet and the Web becomes universal, there has been a great deal of efforts to use it for education among educators throughout the world. The advantage of a Web-based lecture is that people can take it anywhere at a low cost anytime. The demand for learning java programming using the Web is increasing. Accordingly, a number of Web-based Java programming course contents have developed and used. Problems with existing contents are that materials about how to program are not sufficient and the presentation of the lecture is most often separated from the programming environment. In this paper, we present a methodology for developing course contents of Java programming to solve these problems and develop them using it. Then we report the evaluation result of course contents by students who took a Web-based lecture using them.

• Journal of the Ergonomics Society of Korea
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• v.25 no.4
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• pp.121-128
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• 2006

Although population of the elderly is increasing rapidly, the older adults are the least users of the Internet in Korea. Prior research suggests that older adults are physically and psychologically disadvantaged when using the Internet. With the existence of the digital divide over different age groups, the objectives of this study were to identify the current status of Internet usage of Korean adults and to suggest some alternatives for solving digital divide on Internet usage. A total of 654 Korean adults, including the elderly, participated in both on-line and off-line (on-site interview) surveys using structured questionnaires. The results of statistical analyses indicated that the gap between the percentages of Internet users in younger and older groups was significantly wide, though many older adults had strong interests of Internet. To reduce this gap on digital divide, with an appropriate help from family and government, several characteristics of the elderly should be considered in designing some age-related web sites. Some effective alternatives suggested in this study may be used as basic data for universal design of Internet-oriented software.

• Journal of Welding and Joining
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• v.35 no.3
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• pp.35-43
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• 2017

A 3D transient heat transfer model is developed by ABAQUS software to study the temperature distribution during friction stir welding process at different rotational speeds. Furthermore, AA 5083-O plates were joined by FSW technique. For this purpose, a universal milling machine was used to perform the welding process and a mechanical vice was used to fix the work pieces in the proper position. The joints were friction stir welded at a constant travel speed 50 mm/min and two rotational speed values; 400 rpm and 630 rpm using two types of tools; cylindrical threaded pin and tapered smooth one. At each welding condition the temperature was measured using infra-red thermal image camera to verify the simulated temperature distribution. The welded joints were visually inspected as well as by macro- and microstructure evolutions. In addition, the welded joints were mechanically tested for hardness and tensile strength. The maximum peak temperature obtained was at higher rotational speed using the threaded tool pin profile. The results showed that the rotational speed affects the peak temperature, defects formation and sizes, and the mechanical properties of friction stir welded joints. Moreover, the threaded tool gives superior mechanical properties than the tapered one at lower rotational speed.

• The Journal of Advanced Prosthodontics
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• v.1 no.2
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• pp.102-106
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• 2009

STATEMENT OF PROBLEM. Screw loosening has been a common complication and still reported frequently. PURPOSE. The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS. Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated poly-esther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss. RESULTS. TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test). CONCLUSION. Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.3
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• pp.95-104
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• 2017

Positioning signals transmitted by Global Positioning System (GPS) satellites located at approximately 20,000 km height is very weak. For the reason, GPS signals are vulnerable to intentional jamming and unintentional disturbance. Recently, the number of jamming has been increased significantly all over the world. For the applications where continuous and reliable positioning is required when GPS jammers are activated, other positioning systems are strongly required. In this work, a set of Time Division Multiple Access (TDMA)-based transmitters and receivers utilizing Universal Software Radio Peripheral (USRP) and GNU Radio are designed and implemented. To eliminate the undesirable effects of GPS jamming, a frequency band which does not overlap L band is utilized. To demonstrate the accuracy of the proposed method, an experiment was performed.