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Adjacent Interference Analysis between M-WiMAX OFDMA/TDD and WCDMA FDD System in the 2.6 GHz Band Part II : Adjacent Interference Analysis with Smart Antenna in M-WiMAX System (2.6 GHz 대역에서 M-WiMAX OFDMA/TDD 시스템과 WCDMA FDD 시스템간의 상호 간섭 분석 Part II : Adjacent Interference Analysis with Smart Antenna in M-WiMAX System)

  • Wang, Yu-Peng;Ko, Sang-Jun;Chang, Kyung-Hi
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.6A
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    • pp.588-599
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    • 2007
  • This paper presents the coexistence issues between M-WiMAX TDD and WCDMA FDD systems. To improve the M-WiMAX system performance and to reduce the adjacent channel interference to WCDMA FDD system, transmit and receive beamforming techniques are applied in the base stations of M-WiMAX system. Furthermore, we propose an adjacent channel interference modeling methodology, which captures the effect of transmit beamforming on the adjacent channel interference. Besides, we verify the performance improvement in the uplink of WCDMA system due to the transmit beamforming in M-WiMAX downlink based on the proposed adjacent channel interference modeling methodology. We also verify the performance enhancement due to the receive beamforming in the uplink of M-WiMAX system through system level Monte Carlo simulations, considering random user position, the effect of shadowing and multi-path fading channel. Discussions on the gain of applying transmit and receive beamforming in M-WiMAX system comparing the case of SISO system are also included. Furthermore, we present the performance of cosited M-WiMAX and WCDMA systems, considering commercial deployment, additional channel filter at base stations and the effects of TxBF and RxBF.

A Study on Interference Analysis between Base Stations with FDD and TDD Modes for IMT-2000 (FDD 및 TDD 모드 채용 IMT-2000 시스템 기지국간 간섭분석 연구)

  • 이일근;이형수;이정규;신경철;김경태
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.1
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    • pp.11-17
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    • 2001
  • This paper introduces an interference analyzer based on the statistical approach called the Monte Carlo methodology, which has been chosen as one of the interference analyzing techniques in ITU-R. Furthermore, using the interference analyzer developed in this paper with modified Hata model, computer simulation is performed to examine probability of interference affecting between the base stations with FDD and TDD modes for IMT-2000. Through the simulation results, it is confirmed that two different systems with FDD/TDD modes of same frequency bands can be simultaneously used in a cell without significant interference, under the parameter conditions specified in this paper.

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Infiltration in Residential Buildings under Uncertainty (공동주택 침기의 불확실성 분석)

  • Hyun, Se-Hoon;Park, Cheol-Soo;Moon, Hyeun-Jun
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.369-374
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    • 2006
  • Quantification of infiltration rate is an important issue in HVAC system design. The infiltration in buildings depends on many uncertain parameters that vary with significant magnitude and hence, the results from standard deterministic simulation approach can be unreliable. The authors utilize uncertainty analysis In predicting the airflow rates. The paper presents relevant uncertain parameters such as meteorological data, building parameters (leakage areas of windows, doors, etc.), etc. Uncertainties of the aforementioned parameters are quantified based on available data from literature. Then, the Latin Hypercube Sampling (LHS) method was used for the uncertainty propagation. The LHS is one of the Monte Carlo simulation techniques that is suited for our needs. The CONTAMW was chosen to simulate infiltration phenomena in a residential apartment that is typical of residential buildings in Korea. It will be shown that the uncertainty propagating through this process is not negligible and may significantly influence the prediction of the airflow rates.

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Conceptual design of neutron measurement system for input accountancy in pyroprocessing

  • Lee, Chaehun;Seo, Hee;Menlove, Spencer H.;Menlove, Howard O.
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.1022-1028
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    • 2020
  • One of the possible options for spent-fuel management in Korea is pyroprocessing, which is a process for electrochemical recycling of spent nuclear fuel. Nuclear material accountancy is considered to be a safeguards measure of fundamental importance, for the purposes of which, the amount of nuclear material in the input and output materials should be measured as accurately as possible by means of chemical analysis and/or non-destructive assay. In the present study, a neutron measurement system based on the fast-neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) techniques was designed for nuclear material accountancy of a spent-fuel assembly (i.e., the input accountancy of a pyroprocessing facility). Various parameters including inter-detector distance, source-to-detector distance, neutron-reflector material, the structure of a cadmium sleeve around the close detectors, and an air cavity in the moderator were investigated by MCNP6 Monte Carlo simulations in order to maximize its performance. Then, the detector responses with the optimized geometry were estimated for the fresh-fuel assemblies with different 235U enrichments and a spent-fuel assembly. It was found that the measurement technique investigated here has the potential to measure changes in neutron multiplication and, in turn, amount of fissile material.

Development of de-noised image reconstruction technique using Convolutional AutoEncoder for fast monitoring of fuel assemblies

  • Choi, Se Hwan;Choi, Hyun Joon;Min, Chul Hee;Chung, Young Hyun;Ahn, Jae Joon
    • Nuclear Engineering and Technology
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    • v.53 no.3
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    • pp.888-893
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    • 2021
  • The International Atomic Energy Agency has developed a tomographic imaging system for accomplishing the total fuel rod-by-rod verification time of fuel assemblies within the order of 1-2 h, however, there are still limitations for some fuel types. The aim of this study is to develop a deep learning-based denoising process resulting in increasing the tomographic image acquisition speed of fuel assembly compared to the conventional techniques. Convolutional AutoEncoder (CAE) was employed for denoising the low-quality images reconstructed by filtered back-projection (FBP) algorithm. The image data set was constructed by the Monte Carlo method with the FBP and ground truth (GT) images for 511 patterns of missing fuel rods. The de-noising performance of the CAE model was evaluated by comparing the pixel-by-pixel subtracted images between the GT and FBP images and the GT and CAE images; the average differences of the pixel values for the sample image 1, 2, and 3 were 7.7%, 28.0% and 44.7% for the FBP images, and 0.5%, 1.4% and 1.9% for the predicted image, respectively. Even for the FBP images not discriminable the source patterns, the CAE model could successfully estimate the patterns similarly with the GT image.

Global sensitivity analysis improvement of rotor-bearing system based on the Genetic Based Latine Hypercube Sampling (GBLHS) method

  • Fatehi, Mohammad Reza;Ghanbarzadeh, Afshin;Moradi, Shapour;Hajnayeb, Ali
    • Structural Engineering and Mechanics
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    • v.68 no.5
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    • pp.549-561
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    • 2018
  • Sobol method is applied as a powerful variance decomposition technique in the field of global sensitivity analysis (GSA). The paper is devoted to increase convergence speed of the extracted Sobol indices using a new proposed sampling technique called genetic based Latine hypercube sampling (GBLHS). This technique is indeed an improved version of restricted Latine hypercube sampling (LHS) and the optimization algorithm is inspired from genetic algorithm in a new approach. The new approach is based on the optimization of minimax value of LHS arrays using manipulation of array indices as chromosomes in genetic algorithm. The improved Sobol method is implemented to perform factor prioritization and fixing of an uncertain comprehensive high speed rotor-bearing system. The finite element method is employed for rotor-bearing modeling by considering Eshleman-Eubanks assumption and interaction of axial force on the rotor whirling behavior. The performance of the GBLHS technique are compared with the Monte Carlo Simulation (MCS), LHS and Optimized LHS (Minimax. criteria). Comparison of the GBLHS with other techniques demonstrates its capability for increasing convergence speed of the sensitivity indices and improving computational time of the GSA.

Measurement and Arrival Direction Estimation of Supersonic Flight Sonic Boom (초음속 비행체의 소닉붐 측정과 도래각 추정)

  • Ha, Jae-hyoun;Jung, Suk Young;Lee, Younghwan;Jin, Hyeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.3
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    • pp.175-183
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    • 2021
  • This paper studies measurement of sonic boom created by supersonic flight and its arrival angle estimation techniques. Since sonic boom propagates as an impulsive noise and includes infrasound frequency, we propose measurement instrumentation acquiring sonic boom signature without distortion. And we suggest the methodology for an arrival angle estimation with its performance analysis in accordance with sensor array configurations. The performance of our estimator is verified by comparing theoretical performance bound with statistics of its Monte-Carlo simulation results. Furthermore, we presents the analysis of the sonic boom measurement from real flight tests. This work provides an intuitive concept for sensor array configurations and measurement instrumentation.

Quantitative risk assessment for wellbore stability analysis using different failure criteria

  • Noohnejad, Alireza;Ahangari, Kaveh;Goshtasbi, Kamran
    • Geomechanics and Engineering
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    • v.24 no.3
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    • pp.281-293
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    • 2021
  • Uncertainties in geomechanical input parameters which mainly related to inappropriate data acquisition and estimation due to lack of sufficient calibration information, have led wellbore instability not yet to be fully understood or addressed. This paper demonstrates a workflow of employing Quantitative Risk Assessment technique, considering these uncertainties in terms of rock properties, pore pressure and in-situ stresses to makes it possible to survey not just the likelihood of accomplishing a desired level of wellbore stability at a specific mud pressure, but also the influence of the uncertainty in each input parameter on the wellbore stability. This probabilistic methodology in conjunction with Monte Carlo numerical modeling techniques was applied to a case study of a well. The response surfaces analysis provides a measure of the effects of uncertainties in each input parameter on the predicted mud pressure from three widely used failure criteria, thereby provides a key measurement for data acquisition in the future wells to reduce the uncertainty. The results pointed out that the mud pressure is tremendously sensitive to UCS and SHmax which emphasize the significance of reliable determinations of these two parameters for safe drilling. On the other hand, the predicted safe mud window from Mogi-Coulomb is the widest while the Hoek-Brown is the narrowest and comparing the anticipated collapse failures from the failure criteria and breakouts observations from caliper data, indicates that Hoek-Brown overestimate the minimum mud weight to avoid breakouts while Mogi-Coulomb criterion give better forecast according to real observations.

A complete 3D map of Bell Glasstone spatial correction factors for BRAHMMA subcritical core

  • Shukla, Shefali;Roy, Tushar;Kashyap, Yogesh;Shukla, Mayank;Singh, Prashant
    • Nuclear Engineering and Technology
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    • v.54 no.9
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    • pp.3488-3493
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    • 2022
  • Accelerator driven subcritical systems have long been discussed as facilities which can be used for solving the nuclear waste problem. The physics of these systems is very different from conventional reactors and new techniques had to be developed for reactivity monitoring. One such technique is the Area Ratio Method which studies the response of a subcritical system upon insertion of a large number of neutron pulses. An issue associated with this technique is the spatial dependence of measured reactivity which is intrinsic to the sub criticality of the system since the reactor does not operate on the fundamental mode and measured reactivity depends on the detector position. This is generally addressed by defining Bell-Glasstone spatial correction factor. This factor upon multiplication with measured reactivity gives the correct reactivity which is independent of detector location. Monte Carlo Methods are used for evaluating these factors. This paper presents a complete three dimensional map of spatial correction factors for BRAHMMA subcritical system. In addition, the dataset obtained also helps in identifying detector locations where the correction factor is close to unity, thereby implying no correction if the detector is used at those locations.

MODIFICATION OF INITIALLY GROWN BN LAYERS BY POST-N+ IMPLANTATION

  • Byon, E-S.;Lee, S-H.;Lee, S-R.;Lee, K-H.;Tian, J.;Youn, J-H.;Sung, C.
    • Journal of Surface Science and Engineering
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    • v.32 no.3
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    • pp.351-355
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    • 1999
  • BN films with a high content of cubic phase has been deposited by a variety of techniques. It is well known that c-BN films grow with a unique microstructure consisting of sp2 and sp3 bonded layers. Because of existence of the initially grown sp2 /bonded layer, BN films are not adhesive to the substrates. In this study, post-N+ / implantation was applied to improve the adhesion of the films. A Monte Carlo program TAMIX was used to simulate this modification process. The simulation showed nitrogen concentration profile at 1200\AA in depth in case of 50keV -implantation energy. FTIR spectra of the N+ implanted specimens demonstrated a strong change of absorption band at 1380 cm1The films were also investigated by HRTEM. From these results, it is concluded that the post ion implantation could be an effective technique which improves the adhesion between BN film and substrate.

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