• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.5
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• pp.23-33
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• 2008

In this paper, we verify the performance of LDPC coded OFDM/DS system by Monte-Carlo simulation of BER on Eb/No. The simulation results show that LDPC coded OFDM/DS has a strong anti-jamming characteristic over pulse-noise jammer and partial-band noise jammer. The performance of LDPC coded OFDM/DS system is evaluated on both faded waveforms and non-faded waveforms. For non-faded waveforms, high coding gain is attained due to LDPC, even when waveforms have short PN sequence and JSR is only 5dB. Especially, the increase in the repeated number of LDPC decoding enhances coding gain. However, faded waveforms cannot achieve sufficient average effect when PN sequence is short. High coding gain of faded waveforms can be achieved by extending length of PN sequence. In addition, we compare LDPC coded OFDM/DS system with Convolutional coded OFDM/DS system. The simulation results illustrate that when LDPC coded OFDM/DS system with short PN sequence has sufficient average effects, the system shows lower BER than Convolutional coded OFDM/DS system with long PN sequence.

• Earthquakes and Structures
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• v.12 no.3
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• pp.359-374
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• 2017

The seismic events in Northern Italy, May 2012, have revealed the seismic vulnerability of typical Italian precast industrial buildings. The aim of this paper is to present a seismic fragility model for Italian RC precast buildings, to be used in earthquake loss estimation and seismic risk assessment by comparing two building typologies and three different codes: D.M. 3-03-1975, D.M. 16-01-1996 and current Italian building code that has been released in 2008. Based on geometric characteristics and design procedure applied, ten different building classes were identified. A Monte Carlo simulation was performed for each building class in order to generate the building stock used for the development of fragility curves trough analytical method. The probabilistic distributions of geometry were mainly obtained from data collected from 650 field surveys, while the material properties were deduced from the code in place at the time of construction or from expert opinion. The structures were modelled in 2D frameworks; since the past seismic events have identified the beam-column connection as the weakest element of precast buildings, two different modelling solutions were adopted to develop fragility curves: a simple model with post processing required to detect connection collapse and an innovative modelling solution able to reproduce the real behaviour of the connection during the analysis. Fragility curves were derived using both nonlinear static and dynamic analysis.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.647-653
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• 2020

Stainless steel is used commonly in nuclear applications for shielding radiation, so in this study, three different types of new stainless steel samples were designed and developed. New stainless steel compound ratios were determined by using Monte Carlo Simulation program Geant 4 code. In the sample production, iron (Fe), nickel (Ni), chromium (Cr), silicium (Si), sulphur (S), carbon (C), molybdenum (Mo), manganese (Mn), wolfram (W), rhenium (Re), titanium (Ti) and vanadium (V), powder materials were used with powder metallurgy method. Total macroscopic cross sections, mean free path and transmission number were calculated for the fast neutron radiation shielding by using (Geant 4) code. In addition to neutron shielding, the gamma absorption parameters such as mass attenuation coefficients (MACs) and half value layer (HVL) were calculated using Win-XCOM software. Sulfuric acid abrasion and compressive strength tests were carried out and all samples showed good resistance to acid wear and pressure force. The neutron equivalent dose was measured using an average 4.5 MeV energy fast neutron source. Results were compared to 316LN type stainless steel, which commonly used in shielding radiation. New stainless steel samples were found to absorb neutron better than 316LN stainless steel at both low and high temperatures.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.207-214
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• 2001

The KN-12 spent nuclear fuel (SNF) transport cask is designed for transportation of up to 12 assemblies and is in standby status for being licensed in accordance with Korea Atomic Energy Act. To evaluate radiation shielding and criticality safety of the KN-12 cask, each case of study was carried out using MCNP4B Code. MCNP code is verified by performing benchmark calculation for the KSC-4 SNF cask designed in 1989. As a result of radiation safety evaluation for the KN-12 cask, calculated dose rates always satisfied the standards at the cask surface, at 2m from the surface in normal transport condition, and at 1 m from the surface in hypothetical accident condition. Maximum dose rate was always arisen on the side of the cask. For normal transport condition, photons primarily contribute to dose rate between two kinds of released sources, neutrons and photons, from spent nuclear fuel but for hypothetical accident condition, contrary case was resulted. The level of calculated dose rate was 27.8% of the limit at the cask surface, 89.3% at 2 m from the cask surface, and 25.1% at 1 m from the cask surface. For criticality analysis, keff resulting from the criticality analysis considering the condition of optimum partial flooding with fresh water is 0.89708(0.00065. The results confirm the standards recommended by all regulations on radiation safety.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.10
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• pp.1073-1078
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• 2014

In this paper, an effective repeat-back jamming (RBJ) mitigation scheme known assuccessive repeat-back jamming cancellation (SRC) is proposed for the utilization of the successive interference cancellation (SIC) algorithm which is used to mitigate the near-far effect and the multiple-access interference for code division multiple-access communication systems. The proposed scheme uses a combined pseudo-random noise (C-PRN) signal from the estimated major parameters of RBJ signals. To evaluate the performance of the proposed scheme, the root mean squared (RMS) code tracking errors are shown according to the standard deviation of the parameter estimation errors of an RBJ signal, and using the well-known major parameters estimation schemes with a C-PRN signal through Monte-Carlo simulation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.3
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• pp.193-199
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• 2000

As an energetic focused-ion beam(FIB) is irradiated on an inorganic amorphous thin film a majority of ions without a reflection at surface, is randomly collided with constituent atoms in thin film. but their distribution exhibits generally a systematic form of distribution. In our previous paper we reported the concentration distribution and the transmission per unit depth of Ga$^{+}$ ions penetrated int a-Se$_{75}$ /Ge$_{25}$ thin film using the LSS-based calculation. In this paper these simulated results are compared with those obtained by a conventional profile code(ISC) and a practical SIMS profile. Then the results of LSS-based calculation have only a small difference with those of code and SIMS Especially. in the case of Ga$^{+}$-FIB with an accelerating energy of 15keV. the depth of the maximum ion concentration is coincident with each other in an error range of $\pm$5$\AA$.EX>.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3692-3699
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• 2023

The Rare isotope Accelerator complex for ON-line experiments in Korea houses several accelerator complexes. Among them, the µSR facility will be initially equipped with a 600 MeV and 100 kW proton beam to generate surface muons, and will be upgraded to 400 kW with the same energy. Accelerated proton beams lose approximately 20% of the power at the target, and the remaining power is concentrated in the beam direction. Therefore, to ensure safe operation of the facility, concentrated protons must be distributed and absorbed at the beam dump. Additionally, effective dose levels must be lower than the legal standard, and the beam dumps used at 100 kW should be reused at 400 kW to minimize the generation of radioactive waste. In this study, we introduce a tailored method for designing beam dumps based on the characteristics of the µSR facility. To optimize the geometry, the absorbed power and effective dose were calculated using the MCNP6 code. The temperature and stress were determined using the ANSYS Mechanical code. Thus, the beam dump design consists of six structures when operated at 100 kW, and a 400 kW beam dump consisting of 24 structures was developed by reusing the 100 kW beam dump.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.179-184
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• 2018

In this study, we compared the measured values of the effective beam size of standard gamma irradiator with the simulation results to provide a useful means to the effective beam area determination. Results of the simulation and measured using ion chamber was distributed in a relative error of 4.5 ~ 7.3% of the case of air kerma rate. The size of the effective beam area is when the simulation was implemented in the horizontal direction 27cm, 21.6cm vertical direction, the measured result using a film was obtained similar results with the horizontal direction 26.5cm, 21.9cm vertical direction. The relative error in the horizontal direction is 1.85% and 1.38% vertical effective beam area was also similarly distributed around the field gamma rays. As a result of the study, it was confirmed that the effectiveness of the simulation was sufficient for the gamma irradiation system. In particular, it is small relative errors in the effective beam size than the air kerma rate is considered to be due to the size of the beam is determined by geometric factors rather than the capacity of the standard source. A further study is needed to improve the reliability of the photon energy distribution diagram using simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.329-340
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• 2009

This paper proposes a novel code tracking scheme to track the fine code synchronization for BOC(pn,n) modulated spreading signals. The correlation function of BOC(pn,n) modulated spreading signals has been several peaks. In this paper, we observe that the correlation function in the advanced offset region remains almost unchanged, due to the multipath signals being received later than a line-of-sight signal. Based on this observation, we propose a novel code tracking scheme which is called the advanced region correlation (ARC) method for BOC(n,n) modulated spreading signals. And, we compare with the code tracking accuracy between the conventional and proposed methods in the static multipath and land mobile satellite system channels through the Monte-Carlo simulation. Then, base on the proposed scheme, we propose the generalized-ARC (ARC) scheme for BOC(pn, n) modulated spreading signals.

• Radiation Oncology Journal
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• v.28 no.4
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• pp.224-230
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• 2010

Purpose: We designed the aft-multiple-slit (AMS) system to reduce scatter in cone-beam computed tomography (CBCT). As a preliminary study, we performed a Monte Carlo N-Particle Transport Code (MCNP) simulation to verify the effectiveness of this system. Materials and Methods: The MCNPX code was used to build the AMS geometry. An AMS is an equi-angled arc to consider beam divergence. The scatter-reduced projection images were compared with the primary images only and the primary plus scatter radiation images with and without AMS to evaluate the effectiveness of scatter reduction. To obtain the full 2 dimensional (2D) projection image, the whole AMS system was moved to obtain closed septa of the AMS after the first image acquisition. Results: The primary radiation with and without AMS is identical to all the slit widths, but the profiles of the primary plus scattered radiation varied according to the slit widths in the 2D projection image. The average scatter reduction factors were 29%, 15%, 9%, and 8% when the slit widths were 5 mm, 10 mm, 15 mm, and 20 mm, respectively. Conclusion: We have evaluated the scatter reduction effect of the AMS in CBCT imaging using the Monte Carlo (MC) simulations. A preliminary study based on the MCNP simulations showed a mount of scatter reduction with the proposed system.