• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.423-440
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• 2001

For sodium cooling liquid metal reactors during the last 25 years, it was most important to verify the safety of the steam generator, which absolutely requires a water leak detection system with fine sensitivity and response. This study describes the structure and leak classification of the HAMMER (Korea Advanced Liquid Metal Reactor) steam generator, compared with other classifications, and explains the effects of leak development. The requirements and experimental situations for the development of the KALIMER acoustic leak detection system (KADS) which detects micro leaks, not intermediate leaks, are introduced. We proposed four frequency bands, 1∼8kHz, 8∼20kHz, 20∼40kHz and 40∼200kHz, split effectively for analyzing the detected acoustic leak signals obtained from the sodium-water reaction model or water model in the mock-up system.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.352-361
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• 2017

This paper proposes a design and fabrication of the test equipment that is implemented as a part of the airborne tracking radar inspection under the environment of indoor simulation. This test equipment provides controlling the operation status of airborne tracking radar and replicating the velocity and range information of target by generating a variety of target signal. This is mainly composed of radar operation controller, target signal generator, horn antenna driving devices. Radar operation controller is able to perform the controlling of radar operation mode and monitoring in real time by serial communication. Target signal generator is generated doppler signal and range delayed signal using virtual target of RF-band. Horn antenna driving devices perform a role of target simulating exercise. In the end, the performance is demonstrated using experiment results of test equipment for airborne tracking radar.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.209-213
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• 2010

This paper describes the fabrication and characteristics of AlN piezoelectric MPG(micro power generator). The micro energy harvester was fabricated to convert ambient vibration energy to electrical power as a AlN piezoelectric cantilever with Si proof-mass. To be compatible with CMOS process, AlN thin film was grown at low temperature by RF magnetron sputtering and micro power generators were fabricated by MEMS technologies. X-ray diffraction pattern proved that the grown AlN film had highly(002) orientation with low value of FWHM(full width at the half maximum, $\theta=0.276^{\circ}$) in the rocking curve around(002) reflections. The implemented harvester showed the $198.5\;{\mu}m$ highest membrane displacement and generated 6.4 nW of electrical power to $80\;k{\Omega}$ resistive load with $22.6\;mV_{rms}$ voltage from 1.0 G acceleration at its resonant frequency of 389 Hz. From these results, the AlN piezoelectric MPG will be possible to suitable with the batch process and confirm the possibility for power supply in portable, mobile and wearable microsystems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.157-163
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• 2019

A small millimeter-wave tracking radar is a pulse radar that searches, detects, and tracks a target in real time through a TWS (Track While Scan) method on a sea-going traps target with a large RCS running at low speed. This paper describes the development of a simulated signal generator to verify the performance of a small millimeter wave tracking radar in laboratory anechoic chamber environment. We describe a GUI program for testing and performance analysis in conjunction with hardware configuration and tracking radar, and verified the simulated signal generator implemented through performance test.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.88-95
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• 2015

This paper presents a new analysis of RF negative resistance (RFNR) circuits, known as a negative resistance generator. For accurate equation analysis of RFNR, this study examined the effects of the gate resistance and the source parasitic capacitance of the transistor. In addition, the input admittance of the conventional equation was calculated by looking into the source-terminal of the transistor, whereas that of the proposed equation was calculated by examining the gate-terminal of the transistor. The proposed equation analysis is more accurate than that of the conventional analysis, especially for higher frequency range. This paper verify the accuracy of the proposed analysis at high frequency range using the simulation.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.451-451
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• 2012

• Journal of The Korean Radiological Technologist Association
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• v.30 no.1
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• pp.58-62
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• 2004

The purpose of this study was to determine the factors influencing on the size of Radiofrequency ablation using an internally cooled needle electrodes in cattle liver. Ablation procedures involved the use of cool-tip RF system generator and internally coo

• Korean Journal of Radiology
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• v.1 no.4
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• pp.175-184
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• 2000

Although surgical resection remains the best option as potentially curative therapy for hepatocellular carcinoma, radiofrequency thermal ablation has begun to receive much attention as an effective minimally invasive technique for the local control of unresectable malignant hepatic tumors. Most recent radiofrequency devices equipped with a powerful generator and larger needle electrode permit larger thermal lesions, up to 5 cm in diameter, with a single ablation. In this article, the author reviews the technical developments and early clinical results obtained with radiofrequency ablation techniques.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.5
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• pp.197-203
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• 2003

In this paper, we have presented millimeter-wave high conversion gain quadruple subharmonic mixers adopting the cascode harmonic generator The subharmonic mixers were successfully integrated by using 0.1 ${\mu}{\textrm}{m}$ GaAs pseudomorphic HEMTs(PHEMTs) and coplanar waveguide(CPW) structures. Measured output of 1st, 2nd and 4th harmonics of the fabricated cascode 4th harmonic generator are -21.42 dBm, -32.65 dBm and -13.45 dBm, respectively, for an input power of 10 dBm at 14.5 GHz. We showed that the highest conversion gain of 3.4 dB has obtained thus far at a LO power of 13 dBm from the fabricated subharmonic mixers. The millimeter-wave subharmonic mixer also ensure a high degree of isolation showing -53.6 dB in the LO-to-IF and -46.2 dB in the LO-to-RF, respectively, at a frequency of 14.5 GHz. The high conversion gain achieved in this work is the first report among the millimeter-wave subharmonic mixers.

• Journal of the Korean Wood Science and Technology
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• v.37 no.3
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• pp.192-199
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• 2009

This study was carried out to investigate the performance of a radio-frequency/vacuum dryer combined with a mechanical compressive load (RF/VC) with a scale of about $3m^3$ during drying board of Azobe (Lophira alata) and Korean red pine (Pinus densiflora). The degree of vacuum of the RF/VC system was maintained at 80~105 torr, and wood temperature was increased from $40^{\circ}C$ at the beginning of drying to $60^{\circ}C$ at the end of drying and the radiofrequency generator was operated with schedule of 7 minute-ON and 3 minute-OFF. The wood temperatures near charge plate always remained higher than those of the control during all of the drying stage, whereas the wood temperature near ground plate always remained lower than those of the controlled. As drying time proceeding, the temperature of the wood near ground plate presented lower than those of the control. Whereas the temperature of the wood near charge plate presented higher than those of the controlled. The final average moisture contents of the Azobe boards stacked near the input side of the RF generator showed slightly lower than those near the opposite side. Those of the wood stacked in the layers near the charge plate were lower than those of near the ground plate. The average length of surface checks of the Azobe boards stacked near the charge plate was very slight, whereas that toward the ground plate represented high values. The efficiency of input energy was simliar with the commercial systems.