• 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 Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.480-489
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• 1988

Although CDP stacking of common depth gathering is used to get the zero-offset-section, the exploding reflector concept is examined for the modeling of zero source to receiver offset sections in this paper. The acoustic wave equation is compared with a one way wave equation which represents the upgoing wave field only. The one way wave equation used is not derived through an expansion and, therefore, can represent dips up do 90b degrees and may not lost the signals by the dipping angles. There is apparently no simple counterpart of this equation is the space domain and it can be conveniently implemented only by a Fourier method. This paper compares their modeling technique with ray tracing and wave method for over thrust structure which is one of the geological structures are dificult to process and interpret. As a result of modeling much clean and accurate signals, especially, diffractions form the corner and dipping angles can be gathered.

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.313-314
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• 2006

We have investigated the wavelength tuning characteristics due to the vernier effect of coupled-ring reflector laser diode including active region within resonators using time-domain modeling. It is shown that the wavelength can be widely tuned with side mode suppression ratio more than 30dB by adjusting the refractive index difference between mismatched rings.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.315-316
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• 2006

The modulation bandwidth, wavelength chirp of directly modulated coupled-ring reflector laser diode have been investigated using time-domain modeling. For a specific design, the modulation frequency could be 6 GHz and the frequency chirp could be in the range of $120^{\sim}200$ MHz/mA.

• Journal of Navigation and Port Research
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• v.27 no.3
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• pp.267-272
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• 2003

This paper describes design method of Passive-type Radar Reflector (PRR) which is to provide the requirement of newly revised 2000 SOLAS regulations on the Radar Reflector. The main target of this work is to find the optimum shape of a radar target having large Radar Cross Section (RCS). Through the RCS analysis based on the theoretical approach, two kinds of PRR models, RRR-F model for use in fisheries and PRR-S model for use in small sized ship, are designed and discussed their RCS performance. RCS measurement tests for the various sized samples are carried out in an anechoic chamber. As evaluation results it was clearly shown that the conventional sphere-type shows optimum shape in case of PRR-S, while the cylinder-type which consists of large sized corner clusters or zig-zag flat plats gives best performance in case of PRR-F.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.82-90
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• 2013

Concentration errors critically affect the performance of solar concentrator, so their evaluation is important to the concentrated solar power technology. However, the evaluation is very challenging because error sources are various and not easy to measure individually. Therefore, the integrated effect of concentration errors is often more interesting and useful for large-scale applications. In the present work, we analytically investigate and classify various concentration error sources and then explain that the effect of various concentration errors can be represented in terms of a root mean square value of reflector surface slope error. We present an indirect approach to assessing the reflector surface slope error by comparing solar flux measurement data with modeling calculations. We apply the approach for solar furnaces with different thermal capacity and investigate its advantages and disadvantages.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.19-24
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• 1997

In this study, we extend the application of the interface-matrix(IM) method for reflector modeling to Analytic Flux Expansion Nodal (AFEN) method. This include the modifications of the surface-averaged net current continuity and the net leakage balance conditions for IM method in accordance with AFEN fomular. AFEN-interface matrix (AFEN-IM) method has been tested against ZION-1 benchmark problem. The numerical result AFEN-IM method shows 1.24% of maximum error and 0.42% of root-mean square error in assembly power distribution, and 0.006%Δk of neutron multiplication factor. This result proves that the interface-matrix method for reflector modeling can be useful in AFEN method.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.57.1-57
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• 2003

• Journal of electromagnetic engineering and science
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• v.13 no.2
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• pp.113-119
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• 2013

We developed a transformed, symmetrical, mushroom-like surface without via holes in cells focused on a 2.4-GHz WLAN band. Each slot in the novel type structure plays a key role in modeling at the desired frequencies. The designed artificial magnetic conductor (AMC) has several advantages, including a small size, a wider bandwidth, a short reflecting distance to the antenna, and easy fabrication because there are no via holes. Overall dimensions of the AMC cell are 21 mm $(Width){\times}21mm$ $(Height){\times}2.6mm$ (Thickness), and the bandwidth is about three times wider (11.7%) compared to that of a conventional AMC (4.0%). For evaluating the performance of the proposed structure, a reflector, which periodically consists of the designed AMC cells, was developed. The antenna with the investigated AMC reflector not only works within a quarter of the wavelength because of the extremely high wave impedance generated by the AMC cells on the surface of the structure but also reduces the specific absorption rate (SAR). Electromagnetic field (EMF) exposure to a human phantom was analyzed by applying the designed reflector to the 2.4-GHz dipole antenna in a tablet PC. The calculated peak SAR averaged over 1 g was 0.125 W/kg when the input power was 1 W and the antenna was located at 20 cm from the human phantom. However, the SAR value was only 0.002 W/kg (i.e., 98.4% blocked) when the designed reflector was inserted in front of the antenna.

• Journal of information and communication convergence engineering
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• v.4 no.3
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• pp.108-110
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• 2006

Film bulk acoustic resonators for radio frequency wireless applications are presented. Various simulations and modeling were carried out. The impedance of a five-layered FBAR showed almost the same trend of the wideband characteristics as that of an ideal FBAR, but the characteristics of the higher modes appear to be much more suppressed. In addition, the wideband impedance decreased with increasing device size. The resonance characteristics depend strongly on the physical dimensions.