서울대 차세대융합기술연구원

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Publications

Conferences

Study of dispenser cathode development for terahertz vacuum devices application

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz

Barik R.K., Tanwar A.K., Baek I.K., Eom K., Bera A., Sattorov M.A., Min S.H., Kwon O.J., Park G.-S.

Abstract
A Scandium oxide doped tungsten nano-powder for using in high current density thermionic cathode is believed to play a dominant role to improve emission capability. The nano-powder was prepared using sol-gel method by dissolving the blue tungsten and scandium nitrate into the solution. The result shows average particle diameter ∼50 nm, uniform grain size, spherical morphology, uniform phase and homogeneous mixing Sc2O3 doped W nano-powder. Dispenser cathodes will be prepared using this powder and expected excellent emission current density more than 100 A/cm2 which can be used for THz vacuum electron devices. © 2012 IEEE.
Non-bulk-like behavior of hydration water on fluid phase lipids revealed by tera...

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz

Choi D.-H., Son H., Jung S., Park J., Park W.-Y., Kwon O.S., Park G.-S.

Abstract
Hydration state of lipid bilayer during the gel to fluid phase transition is measured with THz time domain spectroscopy (TDS). Hydration water showed bulk-water-like behavior at gel phase, but showed non-bulk-like behavior at fluid phase. © 2012 IEEE.
Automodulation processes in THz resonant backward wave oscillator with low focus...

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz

Sattorov M.A., Khutoryan E., Lukin K., Park G.-S., Kwon O.

Abstract
The automodulation processes in THz resonant backward wave oscillator (BWO) operating at low focusing magnetic field have been studied. Automodulation behavior has been analyzed for different electron beam inclination angles. It has been shown that at low magnetic field the RF transverse electric field leads to steep change of beam-wave interaction power that causes automodulation. The theoretical results are compared with particle-in-cell simulations. © 2012 IEEE.
Determination of relaxation time of DNA hydration water by THz-TDS

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz

Son H., Choi D.-H., Jung S., Park J., Park W.-Y., Kwon O.S., Park G.-S.

Abstract
Interaction of DNA and hydration water affects both structure and function of DNA. Here, we find out the relaxation time of DNA hydration water probed by THz-TDS under biological condition. Double Debye relaxation model is applied for figuring out relaxation time of hydration water. We observed 14.9ps for 50mM of DNA solution. This is much slower compared to bulk water, 8.15ps. The results indicate the existence of slow hydration water around DNA. © 2012 IEEE.
Bending transmission of human hair at terahertz frequency regime

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz

Kim S., Kwon O., Baek I.-K., Eom K., Bera A., Min S.-H., Kwon O.S., Park W.-Y., Park G.-S.

Abstract
Frequency, geometry and dimensional dependences of the single-mode terahertz (THz) wave transmission along a dielectric bent fiber have been investigated. The human hair shaft, which resembles a dielectric rod and thus acts as a waveguide, is used for the transmission experiment. We here show the investigations based on a computational time-domain method in order to fully interpret the experimental results of hair-guided THz wave propagation. The frequency at which the difference between the wave vectors of the incident wave and the waveguide mode is comparable to the reciprocal of the length of the hair bundle gives low bending radiation loss under whole-body irradiation condition due to the maximized coupling coefficient. © 2012 IEEE.
Power estimation of electromagnetic coupling effectiveness by a X-band backward ...

14th IEEE International Vacuum Electronics Conference, IVEC 2013 - Proceedings

Min S.H., Kwon O., Sattorov M., Baek I.K., Kim S.T., Bera A., Barik R.K., Lee W.S., So J.H., Park G.S.

Abstract
Effective electromagnetic coupling with electronic equipment at radiation is used by a high power microwave (HPM) weapons source which means a relativistic backward wave oscillator in here. In the process of researching, developing and using HPM source, we have been studying a real effective coupling source which is able to attack the overall target, suitable in all situation ns. The experimental results show the broken electronic equipment or circuit damages after the radiation by an X-band relativistic backward wave oscillator (RBWO) of a HPM source with mode conversion. We used 500kA-5kA RBWO. The RF power is 0.5GW-30ns at 10GHz with mode conversion radiation from TM01 to TE11. © 2013 IEEE.
Sol-gel synthesis of Sc2O3 doped W nano-particle for cathode application

14th IEEE International Vacuum Electronics Conference, IVEC 2013 - Proceedings

Barik R.K., Bera A., Tanwar A.K., Baek I.K., Eom K., Sattorov M.A., Min S.H., Kwon O.J., Park G.-S.

Abstract
Sc2O3 doped W nano-powder is believed to play a dominant role for improving emission capabilities of the high current density thermionic cathodes. In this study a novel nano-particle synthesis approach was adopted in order to precisely control the particle parameters. The particle characteristics and sintering behavior has been analyzed using SEM, TEM, EDS, XRD and XPS. Uniform grain size with average particle diameter∼50 nm, spherical morphology, uniform phase and homogeneous mixing of Sc 2O3 doped W nano-powder was obtain which will enhance the emission current density, emission uniformity and life of the cathode. © 2013 IEEE.
Cherenkov-like radiation from metallic metamaterials

14th IEEE International Vacuum Electronics Conference, IVEC 2013 - Proceedings

Bera A., Sattorov M.A., Kwon O.J., Barik R.K., Min S.H., Park G.S.

Abstract
The radiation of slit modes excited by convection electron inside a perfect metal film perforated with one dimensional array of cut-through slit is studied. The radiations of non radiating slit modes are achieved by grating coupler which provides the required momentum shift to them. Numerical simulation shows that the radiation intensity of these momentum shifted slit modes are more than that of Smith-Purcell radiation by more than one order magnitude. © 2013 IEEE.
Combination method of atom trap and time-of-flight mass spectrometer for Ca isot...

Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest

Ko K.-H., Jang K.-H., Kim Y., Lee L., Kim T.-S., Park H., Park G.-S., Cha Y.-H., Lim G., Jeong D.-Y.

Abstract
The coupling of the atom trap and the time-of-flight mass spectrometer is demonstrated using calcium atom. The design of the acceleration unit is introduced and the isotope selective characteristics of the systems are discussed. © 2013 IEEE.
Quantitative study of lipid head group effect on long-range hydration dynamics w...

International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz

Choi D.-H., Son H., Jung S., Park J., Park G.-S.

Abstract
Activation energy of phospholipids in aqueous solution was obtained by terahertz (THz) time domain spectroscopy. The THz absorption as a function of temperature, an Arrhenius plot, yields activation energy of water relaxation process. Head group structure and phase dependence of the activation energy is reported. © 2013 IEEE.

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