• Nuclear Engineering and Technology
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• 제49권4호
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• pp.787-791
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• 2017

Americium-beryllium (Am-Be; n, ${\gamma}$) is a neutron emitting source used in various research fields such as chemistry, physics, geology, archaeology, medicine, and environmental monitoring, as well as in the forensic sciences. It is a mobile source of neutron activity (20 Ci), yielding a small thermal neutron flux that is water moderated. The aim of this study is to develop a model to increase the neutron thermal flux of a source such as Am-Be. This study achieved multiple advantageous results: primarily, it will help us perform neutron activation analysis. Next, it will give us the opportunity to produce radio-elements with short half-lives. Am-Be single and multisource (5 sources) experiments were performed within an irradiation facility with a paraffin moderator. The resulting models mainly increase the thermal neutron flux compared to the traditional method with water moderator.

• Journal of Microbiology
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• 제45권4호
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• pp.311-317
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• 2007

In this study, the effects of phosphate concentration and carbon source on the patterns of alkaline phosphatase (APase) and phospholipase (PLase) expression in Vibrio vulnificus ATCC 29307 were assessed under various conditions. The activities of these enzymes were repressed by excess phosphate (4 mM) in the culture medium, but this repression was reversed upon the onset of phosphate starvation in low phosphate defined medium (LPDM) containing 0.2 mM of phosphate at approximately the end of the exponential growth phase. The expressions of the two enzymes were also influenced by different carbon sources, including glucose, fructose, maltose, glycerol, and sodium acetate at different levels. The APase activity was derepressed most profoundly in LPDM containing fructose as a sole carbon source. However, the repression/derepression of the enzyme by phosphate was not observed in media containing glycerol or sodium acetate. In LPDM-glycerol or sodium acetate, the growth rate was quite low. The highest levels of PLase activity were detected in LPDM-sodium acetate, followed by LPDM-fructose. PLase was not fully repressed by high phosphate concentrations when sodium acetate was utilized as the sole carbon source. These results showed that multiple regulatory systems, including the phosphate regulon, may perform a function in the expression of both or either APase and PLC, in the broader context of the survival of V. vulnificus.

• 천문학회보
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• 제38권2호
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• pp.43.1-43.1
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• 2013

We report the preliminary results of our GMVA(Global mm VLBI Array) observation at the frequency of 86 GHz. Observation were made in the dual polarization mode (LCP and RCP), to produce the polarimetric maps with the maximum angular resolution which the array is capable of. We aim to link the source-integrated AGN polarization properties with the polarized spatial source structure, by mapping the polarized "fine structure" of the target AGN. We selected 2 targets, 0954+658 and 0716+714, which (1) have been observed multiple times by the PdBI polarimetric monitoring program; (2) have sufficient integrated fluxes ($S_{90GHz}$ > 1 Jy) ; (3) are close enough to resolve the source structure < 1 pc with given angular resolution ; and (4) are located at high northern declination for good UV coverages. As preliminary results, we present LL and RR polarized images of each target with the maximum angular resolution of ${\sim}60{\mu}as$. Extended structures, probably the jet outflows, are discovered in both sources.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.875-880
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• 2002

It is necessary to determine the vibration source and its transmission paths in order to develop a low-noise compressor. Through the use of multiple-input/single-output(MISO) mode1, the transmission paths of vibration within a reciprocating compressor have been investigated. In order to identify the transmission path, we measure the accelerations of the block and transverse vibrations of the line discharge tube. As outputs, vibrations of compressor shell were measured at three positions; cylinder head, one near the suction line, and the top of upper shell. The partial coherence function and transfer function are obtained ken the measured data, and the results are observed in order to determine vibration source and its influence on the shell vibration.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.239-242
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• 2005

This paper introduced an approach of improvement of performance of Electric device for EMU type Train like as TTX. The electric equipments are characterized by insulation, Noise, cooling system etc. and Their weight arc decided by these factors. There are two kinds of power source in EMU train. First, DC voltage source, 1500 volt, 750 volt is used for subway system. Second, AC power source 25000 volt is applied to high speed train and existing main lines. Composite material has the protection of inrush current and high frequency noise. We can use this material to minimize weight of train. Additionally we can get energy saving when operator service TTX.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.386.1-386
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• 2002

It is necessary to determine the vibration source and its transmission paths in order to develop a low-noise compressor Through the use of multiple-input/single-output(MISO) model, the transmission paths of vibration within a reciprocating compressor have been investigated. In order to identify the transmission path, we measure the accelerations of the block and transverse vibrations of the line discharge tube. (omitted)

• 한국통신학회논문지
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• 제34권9A호
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• pp.649-655
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• 2009

The peak-to-average power ratio (PAPR) regrowth after the clipping is one main disadvantage of space-frequency block coded orthogonal frequency-division multiplexing (SFBC-OFDM). In this paper, we propose a relay assisted low PAPR technique for SFBC-OFDM transmission. For low PAPR at the source (mobile equipment), the relay processes SFBC encoding, which enables the source to transmit clipped single-input single-output (SISO)-OFDM signals without any increase of PAPR. Simulation results show that the clipped signal of proposed scheme is effectively recovered, and the proposed scheme achieves the diversity of SFBC without the complexity of multiple antennas at the source.

• 대한기계학회논문집A
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• 제30권9호
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• pp.1154-1159
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• 2006

In this paper, time-frequency analysis and multi-dimensional spectral analysis methods are applied to source identification and diagnostic of non-stationary sound vibration signals. By checking the coherences for concerned time, this simulation is very well coincident to expected results. The proposed method analyzes the signal instantaneously in both time and frequency domains. The MDSA (Multiple Dimensional Spectral Analysis) analyzes the signal in the plane of instantaneous time and instantaneous frequency at the same time. And it was verified by using the 1500cc passenger car which is accelerated from 70Hz to 95Hz in 4 seconds, the proposed method is effective in determining the vehicle diagnostic problems.

• Journal of Electrical Engineering and Technology
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• 제11권5호
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• pp.1116-1127
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• 2016

• Journal of Power Electronics
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• 제15권4호
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• pp.1054-1065
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• 2015

Multi-functional voltage source inverters (VSIs) have attracted increasing attention in recent years for their advantageous auxiliary services for power quality enhancement in autonomous microgrids. These types of VSIs can not only achieve a proper control scheme in autonomous mode but also cope with the prescribed power quality and stability requirements. These functionalities are integrated within the same device, thereby significantly improving the cost-effectiveness of microgrids while decreasing the investment and bulk compared with those of multiple devices with independent functionalities. Control strategies for power quality enhancement in autonomous microgrids using multi-functional VSIs are comprehensively reviewed in this paper. In addition, such VSIs are discussed in detail, and comparisons of which are also provided. Lastly, a number of future research directions for multi-functional VSIs are recommended.