• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.176-183
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• 2004

In this paper, two-stage low noise amplifier(LNA) for S-band is designed and implemented using ATF54143 HEMT of HP CO. In order to get noise figure and input VSWR to be wanted, it is considered input VSWR and noise figure simultaneously in matching-circuit designing. The fabricated two-stage low noise amplifier has the gain of 27.8dB, input VSWR and output VSWR under 1.5.

• The Journal of the Acoustical Society of Korea
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• v.28 no.1
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• pp.19-24
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• 2009

Investigations of the relation between the stack temperature profile of a standing wave thermoacoustic cooler and the cooling efficiency were performed. Based on the mathematical derivations using the Rott Equation, it was found that the temperature profile along the stack becomes nonlinear as the enthalpy flux passing through the stack increases. It was also found that such nonlinear temperature profiles lower the cooling efficiency. Simulations using a thermoacoustic simulation program called DELTAE showed that the nonlinear temperature profile occurs with a long stack and large cooling load.

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.5-14
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• 2020

This study analyzed the reinforcement effect by conducting laboratory test, model test and program analysis to utilize the surface stabilizer used for the restoration work of collapsed slopes as a reinforcing material for aging reservoirs that exhibits a curing reaction similar to cement. Based on the results of the laboratory test, a model test and program analysis were performed by applying 9% of the mixing ratio. As a result, when the surface stabilizer was used in aging reservoir, it was found that the flow of water only occurred on part of the slope and underground in reservoir. And the water flow could be reduced inside the reservoir. In addition, it was analyzed that the seepage discharge could be reduced by about 42% and the saturated area within the reservoir by about 73%, thereby securing the stability of the aged reservoir.

• Sijohaknonchong
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• v.23
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• pp.189-212
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• 2005

There are the at Royal Banquet(Woiyoa 외연) in the 19th Chosun Dynasty. The is a performance at Royal Banquet by Singing Visitors in Chosun Dynasty. The was performed by the singing male visitors for long times. They sang some Korean Alphbet Songs while congratulators were enjoying the md and drink. The purpose of this wrritten essay is to search the existense of before the 19th century. 1 show the results as follows. 1. There are the records the performed in the Kukjo-Olyeei (國朝五禮儀), Kukjo-Olyeei(國朝五禮儀) is a book of the royal various ceremonial rules in Ealy Chosun Dynasty. 2. There are the records of the performed in the Kukjo-SokOlyeei(國朝續五禮儀). Kukjo-SokOlyeei(國朝五禮儀) is a book of the royal various ceremonial rules in Late Chosun Dynasty. 3. All of the is the same in the order and form. 4. All conculusion the was performed always in Chosun Dynasty.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.9 s.339
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• pp.65-70
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• 2005

For the base station or repeater which is in operation as part of a mobile communication system, any kind of degradation in antenna performance such as lowered gam or increased VSWR which maybe due to aging of antenna, connector corrosion or other environmental factors, is difficult to detect and react to immediately. In this paper, a VSWR measurement device which is capable of detecting the VSWR of a PCS forward path ($1,840\~1,870$MHz) antenna in operation in real time without any interruption in service is developed. Such regular measurement will allow the prediction of any serious failures and insure reliable operation of the antenna. All components of the antenna VSWR measurement device was researched so that the whole system could be produced and shown to be accurate in measuring the YSWR of an actual RF repeater in operation, proving it's effectiveness.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.287-294
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• 2021

In this study, tests were performed to analyze the feasibility of using the ground stabilizer from recycled resources such as blast furnace slag powder as filling material of prebored piles. For this, specimens were prepared by applying 70% and 83% of the general water/binder ratio of the filling material of prebored piles. And compression test, model test, and shaking table test were performed to determine the compressive strength, skin friction on the surface between prebored pile and filling material, and seismic performance of ground stabilizer. As a result of the tests, the compressive strength exceeded the relevant domestic standards, and the skin friction was equivalent to that of ordinary portland cement. In addition, the amount of vertical and horizontal displacement caused by earthquakes was found to be much smaller than the domestic standard. Therefore, when considering the test results comprehensively, it is judged that the feasibility of using a ground stabilizer from recycled resources as filling material for prebored pile is sufficient.

• The Journal of the Acoustical Society of Korea
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• v.20 no.8
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• pp.38-43
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• 2001

We developed a new standing wave type ultrasonic linear motor that can be driven bi-directionally. The operation principle of the motor was derived in an analytical form and the detailed structure was designed by the finite element method. Based on the design, a motor sample and a driving circuit were fabricated, and validity of the structure was verified through experiments.

• 레미콘
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• no.3 s.27
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• pp.62-69
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• 1991

• 레미콘
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• no.12 s.14
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• pp.53-55
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• 1987

• 레미콘
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• no.4 s.51
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• pp.51-59
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• 1997