• Journal of Environmental Science International
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• v.16 no.3
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• pp.255-260
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• 2007

The photocatalytic decolorization of Rhodamine B (RhB) was studied using packed-bed reactor and immobilized $TiO_2/UV$ System. The 20 W UV-A, UV-B and UV-C lamps were employed as the light source. The effect of shape and surface polishing extent of reflector, distance between the reactor and reflector, reactor material were investigated. The results showed that the order of the initial reaction constant with reflector shape was round > polygon > W > rhombus. The optimum distance between the reactor and reflector was 2 cm. The initial reaction constant of quartz reactor was 1.46 times higher than that of tile PVDF reactor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.255-258
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• 2006

In this paper, a novel physical structure for planar spiral inductors is proposed. The spiral inductors were designed and fabricated on multi-layered substrate Bragg-reflector/silicon (BR/Si) wafer. The impacts of multi-layered structure substrate and pattern on characteristics of inductor were studied. Experimental results show that the inductor embedded on Bragg reflector/silicon substrate can achieve the best improvement. At 0.4-1.6 GHz, the Bragg reflector seems to significantly increase the $S_{11}-parameter$ of the inductor.

• Journal of Integrative Natural Science
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• v.7 no.1
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• pp.1-4
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• 2014

Distributed Bragg reflector porous silicon of different characteristics were formed to determine their optical constants in the visible wavelength range using a periodic square wave current between low and high current densities. The surface and cross-sectional SEM images of distributed Bragg reflector porous silicon were obtained using a cold field emission scanning electron microscope. The surface image of distributed Bragg reflector porous silicon indicates that the distributions of pores are even. The cross-sectional image illustrates that the multilayer of distributed Bragg reflector porous silicon exhibits a depth of few microns and applying of square current density during the etching process results two distinct refractive indices in the contrast. Distributed Bragg reflector porous silicon exhibited a porosity depth profile that related directly to the current-time profile used in etch. Its free-standing film was obtained by applying an electro-polishing current.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4583-4590
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• 2023

This study aims at modeling the beryllium reflector poisoning under neutron irradiation conditions and calculating the impact of beryllium poisoning on the core parameters of ETRR-2 research reactor. The CITVAP code was used to calculate the neutron flux and parameters of ETRR-2 core with beryllium reflector elements. The neutron flux in each reflector element was calculated to solve the modeling equations for the atomic densities of lithium-6 (⁶Li), tritium-3 (³H), and helium-3 (³He) using the BERYL program. The results are discussed based on CITVAP calculations of the core excess reactivity and cycle length Full Power Days (FPD). Possible solutions to minimize the degradation due to beryllium poisoning are also discussed and compared based on calculations.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.2
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• pp.255-260
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• 2014

Recently infrared cameras have been widely used to diagnosis degradation status of the power substitution system. At the place of high magnetic field, however, electronic parts of infrared camera take a place problem that is not reasonable working due to high magnetic field. To solve this problem, we may generally use reflector, it has a problem that the performance of reflection degrade caused by flexure of the reflector. In this paper, in order to overcome these problem, technique of design for reflector is proposed to reduce error and to increase measurement efficiency. The reflector is made by coating using aluminum on the acrylic sheet.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.34-39
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• 2015

In this paper, a design of an offset Cassegrain antenna is proposed for Ku and Ka dual-band without increasing the antenna size. For Efficiency of computation and implementation, the frequency selectivity surface (FSS) of reflecting the Ka-band signal and passing the Ku-band is provided for the sub-reflector instead of the main reflector. The proposed FSS hyperboloid sub-reflector is the periodic structure of a unit cell comprising octagon metal rings embedded in the multiple layers. The proposed design is verified for 19 GHz and 45 GHz bands by the use of precise electromagneitc-field simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.3
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• pp.190-194
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• 2019

In this study, the beamforming characteristics of a reflector antenna, such as a phased array antenna, as a feeder have been studied. The beamforming characteristics were examined by observing the actual steering angle of the reflector according to the diameter, the F/D of the reflector, and the number of array elements of the feeder. In addition, the beamforming characteristics were verified by measurement using a reflector of 1.5 m diameter and a four-element log-periodic dipole array(LPDA).

• Journal of the Korean Ceramic Society
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• v.38 no.11
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• pp.980-986
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• 2001

Bragg reflector type FBAR was fabricated on the Si(100) substrate. We measured a frequency response of the resonator at 5.2 GHz and analyzed it by numerical calculation considering actual acoustic losses of each layer in the structure. We fabricated nine layer Bragg reflector of W-SiO$_2$pairs using r.f. sputtering method and fabricated AlN piezoelectric and Al electrodes using pulsed dc sputtering. The return loss(S$_{11}$) of the fabricated Bragg reflector type FBAR was 12 dB at 5.38 GHz and the series resonance frequency(f$_{s}$) was 5.376 GHz and the parallel resonance frequency(f$_{p}$) was 5.3865 GHz. Effective electro-mechanical coupling constant (K$_{eff{^2}}$) and Quality factors(Q$_{s}$), the Figures of Merit of the resonator, were about 0.48% and 411, respectively. We extracted acoustic parameters of AlN piezoelectric and reflection coefficient of the Bragg reflector by numerical calculation. We could know that material acoustic impedance and wave velocity of AlN piezoelectric decreased for intrinsic value and the electromechanical coupling constant(K$_2$) value was very low owing to the poor quality of the AlN piezoelectric. Reflection coefficient of Bragg reflector was 0.99966 and reflection band was very wide from 2.5 to 9.5 GHz.

• Korean Journal of Acupuncture
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• v.27 no.4
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• pp.1-4
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• 2010

Objectives : The purpose of this study is to summarize the historical aspects of parabolic reflector moxa and to suggest the applications of light moxibustion in Korean medicine. Results : Getting a fire by parabolic reflector(concave mirror) is well known because of the Olympic torch lighted with a solar reflector in Greece. From anecdotes or myths for Diocles and Archimedes(third century B.C.) a long history has been chronicled in books and films in western culture. However, it has another history in Asian countries since 2,000 years ago. Some reflectors had a tiny size with 6.5 to 10 cm in diameter, 4 mm to 1 cm thickness, and these mobile handheld devices could make us guess that they have been used for multiple purposes. Bronze reflectors were described in Dongeui-bogam, and excavated from the ancient remains of the Shilla and Koryo dynasties. This common firing device was used as a moxibustion device, one of the acupuncture and moxibustion modalities in traditional Korean medicine. Conclusions : Reflector moxa has been used as a light moxibustion to deliver heat energy to acupuncture points, muscles, and skin along meridians. We present a plausible proposal to improve other phototherapy modalities including reflector moxa in Korean medicine practice.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.273-280
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• 2017

In this paper, a freeform reflector is designed for low road lighting. In the case of low road lighting, which requires light distribution over a wide lane compared to the height, it is difficult to match uniformity, compared to existing road lighting. To satisfy road lighting grade M3, the reflector was divided into nine parts, and the inclination of the reflecting surface was changed to have the desired light distribution. The fitted curves were drawn based on each point, following the formula that was derived. Through the Street Light Simulation of LightTools, we confirmed that it meets the M3 road lighting standard; we then made it directly and satisfied the lighting grade on an actual road, proving the validity of the design result.