• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.114-115
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• 2002

마이크로파 방전에 의한 고압 2-원자 황증기 (high-pressure di-atomic sulfur vapor)는 고효율(high luminous efficacy) 및 고연색성 (high color rendering index)의 백색 광원 (source of white light)으로 높이 평가되고 있다 [1]. 소위 무전극 황전등 (elec출odeless sulfur lamp, ESL)으로 알려진 이 발광원은 최고 효율이 173 lm/w 까지 시연되어 알려진 모든 인조 광원 중에서 가장 높은 효율을 보인 혁신적인 광원이다 [2]. (중략)

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2203-2205
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• 2003

KIRAMS-13, the first medical cyclotron developed by domestic technique, is used to produce radio-isotope such as $^{18}F$ whose life time is relatively short through test operation. For high-power operation of charged particle accelerators, the power coupler must withstand enormous stresses due to charging induced by high RF power passing through. High-power RF testing with peak power in excess of 30kW has been performed on prototype power coupler for KIRAMS-13 normal conducting cavities. CST MICROWAVE STUDIO(CST MWS) is used for fundamental RF Design, and power coupler is manufactured according to fundamental power coupler design requisite. The qualification of the couplers has occurred for the time being only in a limited set of conditions as the available RF system and control instrumentation are under improvement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1300-1305
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• 2014

Equivalent circuits for the waveguide probe with H-shaped small aperture, as a key ingredient of near field microwave microscope, is described along with a working principle of the probe. Small rectangular or circular aperture in comparison with the wavelength behaves like the inductive element. So adding the ridged structure (corresponding to capacitive component) to the small aperture allows the transmission resonance to occur. For verification, we represents the equivalent circuit descriptions for the two types, ridged aperture and cavity types. The values of obtained by use of the equivalent circuit approaches are compared with those obtained by use of the available numerical software. The results are also experimentally verified.

• Smart Structures and Systems
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• v.8 no.1
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• pp.93-105
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• 2011

This paper presents a flexible low-profile antenna sensor for fatigue crack detection and monitoring. The sensor was inspired by the sense of pain in bio-systems as a protection mechanism. Because the antenna sensor does not need wiring for power supply or data transmission, it is an ideal candidate as sensing elements for the implementation of engineering sensor skins with a dense sensor distribution. Based on the principle of microstrip patch antenna, the antenna sensor is essentially an electromagnetic cavity that radiates at certain resonant frequencies. By implementing a metallic structure as the ground plane of the antenna sensor, crack development in the metallic structure due to fatigue loading can be detected from the resonant frequency shift of the antenna sensor. A monostatic microwave radar system was developed to interrogate the antenna sensor remotely. Fabrication and characterization of the antenna sensor for crack monitoring as well as the implementation of the remote interrogation system are presented.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.6
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• pp.1-4
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• 1975

This paper dells with the impedance variations of the IMPATT diode depending upon the small a.c. coomponent superimposed on the d.c. bias. The frequency deviation of the modulated wave is measured using a carrier null method on microwave spectrum analyser. Frequency modulation is achieved by the weack a.c. signal superimposed on the d.c. bias. The bandwidth rapidly increase with increasing modulation signal magnitude for constant modulation frquency and slightly decrease with decreasing modulation frequency for constant modulation signal magnitude.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.406-412
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• 2018

In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.

• ETRI Journal
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• v.45 no.2
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• pp.338-345
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• 2023

A filtering power divider based on air-filled substrate-integrated waveguide (AFSIW) technology is proposed in this study. The AFSIW structure is used in the proposed filtering power divider for substantially reducing the transmission losses. This structure occupies a large area because of the use of air as a dielectric instead of typical dielectric materials. A filtering power divider provides power division and frequency selectivity simultaneously in a single device. The proposed filtering power divider comprises three AFSIW cavities. The filtering function is achieved using symmetrical inductive posts. The input and output ports of the proposed circuit are realized by directly connecting coaxial lines to the AFSIW cavities. This transition from the coaxial line to the AFSIW cavity eliminates the additional transitions, such as AFSIW-SIW and SIW-conductor-backed coplanar waveguide, applied in existing AFSIW circuits. The proposed power divider with a second-order bandpass filtering response is fabricated and measured at 5.5 GHz. The measurement results show that this circuit has a minimum insertion loss of 1 dB, 3-dB fractional bandwidth of 11.2%, and return loss exceeding 11 dB.

• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.189-199
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• 2016

Fast neutrons with a broad energy spectrum, with which it is possible to evaluate nuclear data for various research fields such as medical applications and the development of fusion reactors, can be generated by irradiating proton beams on target materials such as beryllium. To generate short-pulse proton beam, we adopted a deflector and slit system. In a simple deflector with slit system, most of the proton beam is blocked by the slit, especially when the beam pulse width is short. Therefore, the available beam current is very low, which results in low neutron flux. In this study, we proposed beam modulation using a buncher cavity to increase the available beam current. The ideal field pattern for the buncher cavity is sawtooth. To make the field pattern similar to a sawtooth waveform, a multiharmonic buncher was adopted. The design process for the multiharmonic buncher includes a beam dynamics calculation and three-dimensional electromagnetic simulation. In addition to the system design for pulsed proton generation, a test bench with a microwave ion source is under preparation to test the performance of the system. The design study results concerning the pulsed proton beam generation and the test bench preparation with some preliminary test results are presented in this paper.

• Korean Journal of Optics and Photonics
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• v.3 no.2
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• pp.123-132
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• 1992

We designed and constructed the Cs beam tube which consists of a Ramsey cavity, four C-field rods, fluorescence detecting systems, and etc. for developing an optically pumped Cs atomic clock. A semiconductor laser was used for optical pumping and probing in the Cs beam. We observed Ramsey resonance signal by detecting the fluorescence signal in the probing region as the microwave frequency injected into the Ramsey cavity was scanned near 9192.6 MHz which corresponds to the "clock transition" of Cs atoms. We found that the linewidth of the Ramsey signal was 200 Hz, the magnetic field intensity was $8.61\muT$ when the current of 0.8A flowed in the C-field rods, and the second order Zeeman shift by the magnetic field was 3.17 Hz.s 3.17 Hz.

• Journal of the Korean Vacuum Society
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• v.19 no.6
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• pp.467-474
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• 2010

Packet propagation and absorption for the 28 GHz superconducting ECRIS under developing by KBSI Pusan center is analyzed with limited parameter range. The microwave power generated by 28 GHz gyrotron is axially injected to the plasma cavity through waveguide system. According to the analytical ray tracing calculation, the wave packet launched quasi-longitudinally at a high magnetic field side changes its direction from outward to inward as it is approaching resonance layer. Therefore, initially diverging wave does not likely hit a conducting surface before absorbing by electron cyclotron resonance. Also, absorption by plasma with moderate electron density is so strong that reflection by an extraction plate may not be expected.