• Computational Structural Engineering
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• v.7 no.3
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• pp.95-103
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• 1994

The safety related components in the nuclear power plant should be designed to withstand the seismic load. Among these components the integrity of reactor internals under earthquake load is important in stand points of safety and economics, because these are classified to Seismic Class I components. So far the modelling methods of reactor internals have been investigated by many authors. In this paper, the dynamic behaviour of reactor internals of Yong Gwang 1&2 nuclear power plants under SSE(Safe Shutdown Earthquake) load is analyzed by using of the simpled Global Beam Model. For this, as a first step, the characteristic analysis of reactor internal components are performed by using of the finite element code ANSYS. And the Global Beam Model for reactor internals which includes beam elements, nonlinear impact springs which have gaps in upper and lower positions, and hydrodynamical couplings which simulate the fluid-filled cylinders of reactor vessel and core barrel structures is established. And for the exciting external force the response spectrum which is applied to reactor support is converted to the time history input. With this excitation and the model the dynamic behaviour of reactor internals is obtained. As the results, the structural integrity of reactor internal components under seismic excitation is verified and the input for the detailed duel assembly series model could be obtained. And the simplicity and effectiveness of Global Beam Model and the economics of the explicit Runge-Kutta-Gills algorithm in impact problem of high frequency interface components are confirmed.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.169-175
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• 2018

This study deals with a process for the recovery of hydrogen isotopes from methane ($CQ_4$) and water ($Q_2O$) containing tritium in the nuclear fusion exhaust gas (Q is Hydrogen, Deuterium, Tritium). Steam Methane Reforming and Water Gas Shift reactions are used to convert $CQ_4$ and $Q_2O$ to $Q_2$ and the produced $Q_2$ is recovered by the subsequent Pd membrane. In this study, one circulation loop consisting of catalytic reactor, Pd membrane, and circulation pump was applied to recover H components from $CH_4$ and $H_2O$, one of $CQ_4$ and $Q_2O$. The conversion of $CH_4$ and $H_2O$ was measured by varying the catalytic reaction temperature and the circulating flow rate. $CH_4$ conversion was 99% or more at the catalytic reaction temperature of $650^{\circ}C$ and the circulating flow rate of 2.0 L/min. $H_2O$ conversion was 96% or more at the catalytic reaction temperature of $375^{\circ}C$ and the circulating flow rate of 1.8 L/min. In addition, the amount of $CQ_4$ generated by Korean Demonstration Fusion Power Plant (K-DEMO) in the future was predicted. Then, the treatment process for the $CQ_4$ was proposed and HAZOP (hazard and operability) analysis was conducted to identify the risk factors and operation problems of the process.

• Journal of Radiation Industry
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• v.9 no.2
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• pp.85-90
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• 2015

Purpose: Time of operation has been reduced and accuracy of operation has been improved since C-arm, which offer real-time image of patient, was introduced in operation room. However, because of the contamination of patient, C-arm could not be used more appropriately. Therefore, this study is to know factors of controlling exposure dose, image quality and the exposed dose of health professional in operation room. Materials and methods: Height of Wilson frame (bed for operation) was fixed at 130 cm. Then, Model 76-2 Phantom, which was set by assembling manual of Fluke Company, was set on the bed. Head/Spine Fluoroscopy AEC mode was set for exposure condition. According to detector size of C-arm, the absorbed dose per min was measured in the 7 steps OFD (cm) from 10 cm to 40 cm (10, 15, 20, 25, 30, 35, 40 cm). In each step of OFD, the absorbed dose per min of same diameter of collimation was measured. Moreover, using Nero MAX Model 8000, exposure dose per min was measured according to 3 step of distance from detector (20 cm, 60 cm, 100 cm). Finally, resolution was measured by CDRH Disc Phantom and magnification of each OFD was measured by aluminum stick bar. Result: According to detector size of C-arm, difference of absorbed dose shows that the dose of 20 cm OFD is 1.750 times higher than the dose of 40 cm OFD. It means that the C-arm, which has smaller size of detector, shows the bigger difference of absorbed dose per min (p<0.05). In the difference of absorbed dose in the same step of OFD (from 20 cm to 40 cm), the absorbed dose of 9 inch detect or C-arm was 1.370 times higher than 12 inch' s (p<0.05). When OFD was set to 20 cm OFD, the absorbed dose of non-collimation case was approximately 0.816 times lower than the absorbed dose of collimation cases (p<0.05). When the distance was 20 cm from detector, exposed does includes first-ray and scatter-ray. When the distance was 60 cm and 100 cm from detector, exposed does includes just scatter-ray. So, there was the 2.200 times difference of absorbed does. Finally, when OFD was increased, spatial resolution was 4 to 5 step was increased. However, low contrast resolution was not relative. Moreover, there was 1.363 times difference of magnification (p<0.05). Conclusion: When C-Arm is used, avoiding contamination of patient is more important factor than reducing exposed dose of health professional in operation room. Just controlling exposure time is just way to reduce the exposed does of workers. However, in the case, non-probability influence could be occurred. Therefore, this study proved that the exposed dose will be reduced if the factors such as using small detector size of C-arm, setting OFD from 20 cm to 25 cm and non-collimating. Moreover, dose management of C-arm in the non-interesting area will be considered additionally.

• Progress in Medical Physics
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• v.21 no.1
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• pp.35-41
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• 2010

The purpose of this study is to quantitate regional neurochemical profile of regional normal adult mice brain and assess regional metabolic differences by using ex vivo $^1H$ high-resolution magic angle spinning nuclear magnetic resonance spectroscopy ($^1H$ HR-MAS NMRS). The animals were matched in sex and age. The collected brain tissue included frontal cortex, temporal cortex, thalamus, and hippocampus. Quantitative 1D spectra were acquired on 40 samples with the CPMG pulse sequence (8 kHz spectral window, TR/TE = 5500/2.2 ms, NEX = 128, scan time: 17 min 20 sec). The mass of brain tissue and $D_2O$+TSP solvent were 8~14 mg and 7~13 mg. A total of 16 metabolites were quantified as follow: Acet, NAA, NAAG, tCr, Cr, tCho, Cho, GPC + PC, mIns, Lac, GABA, Glu, Gln, Tau and Ala. As a results, Acet, Cho, NAA, NAAG and mIns were showed significantly different aspects on frontal cortex, hippocampus, temporal cortex and thalamus respectively. The present study demonstrated that absolute metabolite concentrations were significantly different among four brain regions of adult mice. Our finding might be helpful to investigate brain metabolism of neuro-disease in animal model.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.253-259
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• 2004

in this study, we developed a Monte Carlo imaging simulation code written by the visual C$\^$++/ programing language for design optimization of a digital X-ray imaging system. As a digital X-ray imaging system, we considered a Gd$_2$O$_2$S(Tb) scintillator and a photosensor array, and included a 2D parallel grid to simulate general test renditions. The interactions between X-ray beams and the system structure, the behavior of lights generated in the scintillator, and their collection in the photosensor array were simulated by using the Monte Carlo method. The scintillator thickness and the photosensor array pitch were assumed to 66$\mu\textrm{m}$ and 48$\mu\textrm{m}$, respertively, and the pixel format was set to 256 x 256. Using the code, we obtained X-ray images under various simulation conditions, and evaluated their image qualities through the calculations of SNR (signal-to-noise ratio), MTF (modulation transfer function), NPS (noise power spectrum), DQE (detective quantum efficiency). The image simulation code developed in this study can be applied effectively for a variety of digital X-ray imaging systems for their design optimization on various design parameters.

• Investigative Magnetic Resonance Imaging
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• v.12 no.1
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• pp.8-19
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• 2008

Purpose : To investigate the 3-bond and spatial connectivity of human brain metabolites by scalar coupling and dipolar nuclear Overhauser effect/enhancement (NOE) interaction through 2D- correlation spectroscopy (COSY) and 2D- NOE spectroscopy (NOESY) techniques. Materials and Methods : All 2D experiments were performed on Bruker Avance 500 (11.8 T) with the zshield gradient triple resonance cryoprobe at 298 K. Human brain metabolites were prepared with 10% $D_2O$. Two-dimensional spectra with 2048 data points contains 320 free induction decay (FID) averaging. Repetition delay was 2 sec. The Top Spin 2.0 software was used for post-processing. Total 7 metabolites such as N-acetyl aspartate (NAA), creatine (Cr), choline (Cho), lutamine (Gln), glutamate (Glu), myo-inositol (Ins), and lactate (Lac) were included for major target metabolites. Results : Symmetrical 2D-COSY and 2D-NOESY pectra were successfully acquired: COSY cross peaks were observed in the only 1.0-4.5 ppm, however, NOESY cross peaks were observed in the 1.0-4.5 ppm and 7.9 ppm. From the result of the 2-D COSY data, cross peaks between the methyl protons ($CH_3$(3)) at 1.33 ppm and methine proton (CH(2)) at 4.11 ppm were observed in Lac. Cross peaks between the methylene protons (CH2(3,$H{\alpha}$)) at 2.50ppm and methylene protons ($CH_2$,(3,$H_B$)) at 2.70 ppm were observed in NAA. Cross peaks between the methine proton (CH(5)) at 3.27 ppm and the methine proton (CH(4,6)) at 3.59 ppm, between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(4,6)) at 3.59 ppm, and between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(2)) at 4.05 ppm were observed in Ins. From the result of 2-D NOESY data, cross peaks between the NH proton at 8.00 ppm and methyl protons ($CH_3$) were observed in NAA. Cross peaks between the methyl protons ($CH_3$(3)) at 1.33 ppm and methine proton (CH(2)) at 4.11 ppm were observed in Lac. Cross peaks between the methyl protons (CH3) at 3.03 ppm and methylene protons (CH2) at 3.93 ppm were observed in Cr. Cross peaks between the methylene protons ($CH_2$(3)) at 2.11 ppm and methylene protons ($CH_2$(4)) at 2.35 ppm, and between the methylene protons($CH_2$ (3)) at 2.11 ppm and methine proton (CH(2)) at 3.76 ppm were observed in Glu. Cross peaks between the methylene protons (CH2 (3)) at 2.14 ppm and methine proton (CH(2)) at 3.79 ppm were observed in Gln. Cross peaks between the methine proton (CH(5)) at 3.27 ppm and the methine proton (CH(4,6)) at 3.59 ppm, and between the methine proton (CH(1,3)) at 3.53 ppm and methine proton (CH(2)) at 4.05 ppm were observed in Ins. Conclusion : The present study demonstrated that in vitro 2D-COSY and NOESY represented the 3-bond and spatial connectivity of human brain metabolites by scalar coupling and dipolar NOE interaction. This study could aid in better understanding the interactions between human brain metabolites in vivo 2DCOSY study.

• Journal of radiological science and technology
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• v.38 no.2
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• pp.163-170
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• 2015

The interest of the people in the radioactive contamination of the water has increased significantly and the study about analysis and management of radioactive materials are being actively conducted. And monitoring spots have been expanded to the range of public water as well as drinking water by publishing the rule of drinking water quality standards and examination in the Environmental Enforcement Ordinance No. 553 of Korea. In this study, US EPA was investigated as the foreign advanced cases and the way that is appropriate for the Korea was sought by analyzing investigate radionuclide, interval and management. As a result, in the selection part of investigate radionuclide, geological survey, status of nuclear power plants and the presence of the use of artificial radionuclides of the Korea should be investigated and additionally after the selection of a few radionuclides, the systems should be extended to cover all possible radionuclides by considering radioactive pollution levels in humans may be exposed due to the annual drinking water. In the part of the investigate interval, the concept(MCL, DL) should be set up for preventing concentration detection of above MCL and it needs to the maintenance and management. For example, when the concentration is more than MCL, it should be investigated on a quarterly and when the concentration is lower than MCL, it should be investigated to each different interval and management. And the US EPA divided the management area and make the roadmap for managing drinking water. The each classified area has been organized to match the state budget and labor force and the individual data have been managed effectively by HPGe, the NaI, TLD and so on.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.25-34
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• 2012

In order to verify that the recently proposed two-parameters site classification system and the corresponding site coefficients are suitable for the local geological conditions in Korea, a comparison was conducted with current Korean seismic code, Eurocode-8, NYC DOT seismic code. The design spectrum of the current Korean seismic code is significantly amplified in the long-period range, whereas the other response spectra, including the proposed two-parameters approach, are significantly amplified in the short-period range, which is a typical geological condition in Korea. In addition, based on the results of site response analyses in the specific $10km{\times}10km$ area of Gyeongju, spatial distributions of site coefficients from site-specific seismic response analyses were compared with the proposed site coefficients, as well as those specified in the current Korean seismic code. The site coefficients ($F_a$ and $F_v$) from the current Korean seismic codes show significantly high spatial error distributions compared with those specified by the two-parameters site classification system. Therefore, the proposed system is suitable for regions of shallow bedrock including the Korean peninsula.

• Journal of the Korean Geotechnical Society
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• v.28 no.3
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• pp.35-43
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• 2012

Following the companion paper (I. Comparisons with Well-known Seismic Code and Site Response Characteristics), several acceleration data recorded during recent earthquake events in Korea were analyzed to verify the suitability of the proposed two-parameters site classification system and the corresponding site coefficients. For all of rock-soil site pairs less than 30 km distant, response spectrums and corresponding site coefficients, $F_a$ and $F_v$, were determined. Unfortunately, some of data have an eccentric error, where the spectral acceleration of rock site is more amplified than that of soil site. The $F_a$ and $F_v$ for all of pairs except the pairs of error were compared with those in the current code and the proposed system. The $F_a$ and $F_v$ from the recorded motions show definitely different trend from that of the current code. In addition, the site coefficients from recorded motions at four 765 kV substation sites, which are several hundred meters distant, have a remarkably similar trend and absolute values to those in proposed two-parameters site classification system. Based on earthquake motions recorded in domestic areas including data from the four 765 kV substation sites, the two-parameters site classification and site coefficients are superior to the results obtained from the current Korean seismic code.

• Fire Science and Engineering
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• v.26 no.6
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• pp.15-23
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• 2012

Indirect Test Method is often used instead of direct test method in test method for extinguishing performance of $CO_2$ extinguishing facility because of high cost, environment problems and difficulties of procedure. But in the danger facilities for a unit of nation, such as a petrochemical plant, a nuclear power plant, or etc. is better to verify the performance of the extinguishment through direct discharge test. In $CO_2$ extinguishing system for total flooding system installed in dangerous facilities in Korea, each protected area in surface fire and deep-seated fire had selected and verified of extinguishing performance of $CO_2$ extinguishing facilities. To get recognized as extinguishing performance, discharged $CO_2$ concentration to protected area should be equivalence with design concentration standards (NFSC and NFPA). The Design Concentration means that $CO_2$ extinguishing agent is considerate of concentration for percentage of allowance (20 %) from extinguishing concentration which available to control of flame. As test result, surface fire and deep seated fire in protected area is obtained $CO_2$ design concentration and maintained design concentration more than 20 minutes as deep-seated fire. Through this study, we introduced direct discharging test method and decision method. And furthermore, especially in the dangerous facilities as a unit of Nation, we suggested necessity about reliability of extinguishing facilities to use direct test method.