• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.155-161
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• 1996

For the condition monitoring of the journal bearing in rotating machinery, a system for their diagnosis by acoustic emission(AE) was developed. AE has been used to detect abnormal conditions in the bearing system. It was found from the field application study as well as the laboratory experiment using a simulated journal bearing system that AE RMS voltage was the most efficient parameter for the purpose of current study. Based on the above results, algorithms and judgement criteria for the diagnosis system was established. The system is composed of four parts as follows: the sensing part including AE sensor and preamplifier, the signal processing part for RMS-to-DC conversion to measure AE ms voltage, the interface part for transferring RMS voltage data into PC using A/D converter, and the software part including the graphic display of bearing conditions and the diagnosis program.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.60-64
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• 2004

In this paper, we implemented a real-time remote home monitoring system which we have ported the Linux OS and HTTP(Hypertext Transfer Protocol) web server. The GoAhead web server was ported using by ARM cross compiler. And then we used the analog to digital converter ADC0809 for sensing the vii able input signal at widely separated home. We have implemented linux device driver for ADC(Analog to Digital Convertor) and CGI-C(Common Gateway Interface - C language) application program using Client pull method for monitoring real-time changing data. The factor of monitoring is temperature, intensity of illumination and gas's existence. And this system has ability which check the status of out door and gas valve. We have designed the embedded web server system for home emergency monitoring in low cost.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.174-181
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• 2014

Design procedure of LEG(Linear Electric Generator) is introduced by performing the time-domain analysis for the heaving motion of a floating buoy coupled with LEG. A vertical truncated buoy is selected as a point absorber and a double-sided Halbach array mover and cored slotless stator is adopted as a linear electric generator. LEG with a double-sided Halbach array mover and cored slotless stator is designed with the input data such as the heave motion velocity and wave exciting forces in time-domain. The validity of designed LEG is confirmed by performing generating-characteristic-analysis under the sinusoidal motion of a buoy, based on the numerical techniques such as FE(Finite Element) analysis. In particular, an ECM(Equivalent Circuit Method) is employed as the design tool for the prediction of generating characteristics under irregular wave conditions. Finally, we confirm that the ECM gives reasonable and fast results without sacrifice of accuracy.

• Journal of Fashion Business
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• v.4 no.4
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• pp.17-28
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• 2000

The purpose of this study is to analyze the recognition of and the preference for a fashion specialist among students from 4-year and 2-year colleges in Taegu, in order to provide basic data for the effective management methods for the students. The objects of the survey were students in Taegu and Kyungbuk province; 287 students from 4-year colleges and 430 students from 2-year colleges, making the total of 717 students. The survey tool was a questionnaire, which consists of 7 general questions, 7 major curriculum related questions, and 6 questions regarding the information about a fashion specialist, and students career plan. It also contains 3-level Licurt type questionnaire on the recognition of and the preference for a fashion specialist from 20 professional fields. SPSS is used for frequency, percentage, average, standard deviation, $x^2$-test and ANOVA. The results of this study are as follows: 1. The students' motivation in choosing their major as clothing and fashion design was out of independent career plan (86.7%). They were quite content with their major but were unsatisfactory with the current curriculum. 2. The subjects students thought necessary in preparing to be a fashion specialist were pattern, clothing construction (40.1%), clothing design (33.7%), and fashion marketing (18.9%). The answer to the question about the most important subject in the future was fashion marketing (57.2%). 3. What students consider most in choosing a job was aptitude and ability (70.8%). The most preferable clothing types that students want to work with after graduation were womens clothing (52.1%) and wedding dress (18.1%). 4. The means of getting information on a fashion specialist were magazines or broadcasting (72%) and school lectures (20.6%), and there was a significant deference among colleges. 5. Fashion coordinator was the highest recognized specialist (2.64) and the lowest was fashion converter (1.23) among other fashion specialists. 4-year college students had higher recognition in all areas (20 areas) than 2-year college students, and there was a significant deference among colleges in 20 areas.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.643-645
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• 2013

When you convert word processor files with large amounts of input data to PDF files in on/off line, current PDF conversion solutions do one of the source files to perform the conversion task in the Windows PDF virtual printer environment. Depending on the size of the original PDF file conversion speed to convert PDF to do a large amount of different and if you are performing a very slow speed. When you convert files to PDF in this sequence, depending on the capacity of the original file, PDF conversion rate is different, if automating a mass conversion to the PDF, the speed is very slow. In this paper, the PDF conversion which can use the Windows Terminal Server from one Windows Server when performing a PDF conversion processing of the source file, to create a multi-session Terminal, to perform the PDF conversion process at the same time was studied.

• Water for future
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• v.28 no.6
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• pp.183-191
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• 1995

Applying microwave, a velocity measurement system has been developed in order to measure the velocity of stream water surface. It's main purpose is the measurement for high velocity of flood water. It is under the developing stage of experimental measurement system. The microwave surface velocity meter uses Doppler effects of microwave. It consists of a radio frequency(RF) part and that of signal processing. Thr RF part has the function of microwave oscillation, reception of reflected wave, and determination of Doppler frequency, etc. Signal processing designates amplification, fast Fourier transform, etx. Various measuring experiments were performed at bridges and a spillway of Taechong re-regulation dam with the microwave velocity meter. Verification test was also made through water tank of ship model test at Research Institute of Ships and Ocean Engineering. It shows 4% error inherent in A/D converter and additional several percentage errors from measurement circumstance. The measuring ranges are from 0.5 to 3.5 m/s. The result shows good linear relationship between carriage velocity and measured velocity, thus proves usefulness as a measuring instrument for flood water velocity. The instrument requires overall re-engineering procedure and number of data should be accumulated and analyzed to treat wind effects and random fluctuations of water surface.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.330-335
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• 2012

Brushless doubly-fed machine (BDFM) doesn't use brush and slip ring, and has advantages such as high system reliability, small capacity of its frequency converter, low system cost, adjustable power factor and speed, etc. At the same time, it has good applicable potentials on the variable frequency motors and the variable speed constant frequency generators. However, due to the complicacy and particularity of BDFM in the structure and operating mechanism, the effect of magnetic field modulation directly influences the operating efficiency of BDFM. To study the effect of different cage rotor structures on the magnetic field modulation of BDFM, the rotor magnetomotive force (MMF) of BDFM with cage rotor is studied by the analytical method. The components and features of rotor harmonic MMFs are discussed. At the same time, the method to weaken the higher harmonics is analyzed by the theoretic formulae. Furthermore, the magnetic field modulation mechanism is expounded on in detail and the relationship between the magnetic field modulation effect and the operating efficiency of BDFM is established. And then, a new method for estimating the magnetic field modulation effect is proposed. At last, the magnetic field modulation effects of four BDFM prototypes with different cage rotor structures are compared by the MMF analysis and the efficiency data of electromagnetic design. The results verify the effectiveness of the new method for estimating the magnetic field modulation effect of BDFM with cage rotor.

• Journal of Ocean Engineering and Technology
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• v.31 no.4
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• pp.308-314
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• 2017

The purpose of this study was to investigate the sea floor using a seismic profiler in the northern part of Chagwi-do of Jeju Island in order to select the optimal location for the 60-m-class berth of a sea test bed for wave energy converters and provide basic environmental data for designing a suction anchor. The echo types of the seismic profiles were classified based on the study of Kim et al. (2016a), and the location for installing the suction anchor was selected based on a sediment thickness of more than 10 m. The physical properties of the surface sediments were determined by analyzing the sediment samples obtained from 16 grab sample points. Based on the investigation and analysis, we proposed a survey area in the North-Eastern sea as an optimum location for the 60-m-class berth where the suction anchor could be installed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.94-102
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• 2003

This paper describes the load parallel type full-bridge high frequency resonant inverter can be used as power source. Output control method of proposed circuit is compared with pulse frequency modulation(PFM), pulse width modulation(PWM) and pulse phase variation(Phase-Shift). The analysis of the proposed circuit is generally described by using the normalized parameters. The principle of basic operating and the its characteristics are estimated according to the parameters such as switching frequency(${\mu}$), pulse width($\theta$d) the variation of phase angle($\phi$) by three driving signal patterns. Experimental results are presented to verify the theoretical analysis result. In future, Characteristics by three driving signal control method is provided as useful data in case of output control of a power supply in various fields as induction heating application, DC-DC converter etc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1820-1826
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• 2013

Heterogeneous field sensor network between sensor to sensor is designed the CAN method to bus type structure in most using at industry. This Network is supporting a distance vector routing protocol on a characteristic structural a bus type. Also This network support to convert as making separate routing table in heterogeneous network. However distance vector routing protocol make a problem of decrease efficiency because of restriction of network expandability and low transmission process. We propose new CAN routing protocol to support network expandability and high transmission process of industry network. New CAN routing protocol structure addition priority and optional function field based on RIPv2. We established heterogeneous field sensor network, we measure data Throughput(bits/sec) for confirm new CAN routing protocol to increase efficient in industry.