• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.301-316
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• 1995

experimental and computational studies ore carried out to investigate the natural convection of the single phase flow in a tank with a heated horizontal plate facing downward. This is a simplified model for investigations of the influence of a core melt at the bottom of a reactor vessel on the thermal hydraulic behavior in a oater filled cavity surrounding the vessel. In this case the vessel is simulated by a hexahedron insulated box with a heated plate Horizontally mounted at the bottom of the box. The box with the heated plate is installed in a water filled hexahedron tank. Coolers are immersed in the U-type water volume between the box and the tank. Although the multicomponent flows exist more probably below the heated plate in reality, present study concentrates on the single phase flow in a first step prior to investigating the complicated multicomponent thermal hydraulic phenomena. In the present study, in order to get a better understanding for the natural convection characteristics below the heated plate, the velocity and temperature are measured by LDA(Laser Doppler Anemometry) and thermocouples, respectively. And How fields are visualized by taking pictures of the How region with suspended particles. The results show the occurrence of a very effective circulation of the fluid in the whole How area as the heater and coolers are put into operation. In the remote region below the heated plate the new is nearly stagnant, and a remarkable temperature stratification can be observed with very thin thermal boundary. Analytical predictions using the FLUTAN code show a reasonable matching of the measured velocity fields.

• 지역과문화
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• v.5 no.1
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• pp.65-84
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• 2018

The purpose of this study is to develop education programs for effective education of Jeong-gan-bo. Jeong-gan-bo is a unique piece of music made during King Sejong's reign. Starting in the third grade elementary school, Jeong-gan-bo begins to develop. If you fail to understand Jeongganbo in lower grades, you often give up scores of music in a more detailed and complicated manner. This is why we need a customized education program for the first time in lower grades. For this purpose, the basic process of understanding the Jeongganbo is understood to be played as a traditional play. This study consists of the elementary school the 3rd grade scenario. This study consists of the second - grade class scenarios for the 3rd grade elementary school students, the curriculum is centered on the curriculum, which is currently in the 3rd grade curriculum, curriculum in 2009. The program learns to play the rhythm of the 1st phase, the code of the 2nd stage of Jeong-dan, and play the rhythm through play through play. Step 1 is not only visually recognizable, but also a direct sign of the code. The second phase consists of the basic composition of Jeongganbo, through the basic composition of Jangdan, and learns the exact rhythm of Jeongganbo. The results of the study can be divided into meaningful meaning in terms of educational significance and educational content development in terms of educational significance. The methods used to understand the exercises and play games were effective in understanding the contents of Jeongganbo, and also meaningful to the role of traditional music in the context of various programs.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.1
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• pp.55-61
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• 2015

When a radiation detector is applied to the measurement of the radioactivity of high-level of radioactive materials or the rapid response to the nuclear accident, several collimators with the different inner radii should be prepared according to the level of dose rate. This makes the in-situ measurement impractical, because of the heavy weight of the collimator. In this study, an IRIS collimator was developed so as to have a function of controlling the inner radius, with the same method used in optical camera, to vary the attenuation ratio of radiation. The shutter was made to have the double tungsten layers with different phase angles to prevent the radiation from penetrating owing to the mechanical tolerance. The performance evaluation through the MCNP code was conducted by calculating the attenuation ratio according to the inner radius of the collimator. The attenuation ratio was marked on the outer scale ring of the collimator. It is expected that when a radiation detector with the IRIS collimator is used for the in-situ measurement, it can change the attenuation ratio of the incident photon to the detector without replacing the collimator.

• Nuclear Engineering and Technology
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• v.50 no.2
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• pp.268-279
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• 2018

The ALCYONE multidimensional fuel performance code codeveloped by the CEA, EDF, and AREVA NP within the PLEIADES software environment models the behavior of fuel rods during irradiation in commercial pressurized water reactors (PWRs), power ramps in experimental reactors, or accidental conditions such as loss of coolant accidents or reactivity-initiated accidents (RIAs). As regards the latter case of transient in particular, ALCYONE is intended to predictively simulate the response of a fuel rod by taking account of mechanisms in a way that models the physics as closely as possible, encompassing all possible stages of the transient as well as various fuel/cladding material types and irradiation conditions of interest. On the way to complying with these objectives, ALCYONE development and validation shall include tests on $PWR-UO_2$ fuel rods with advanced claddings such as M5(R) under "low pressure-low temperature" or "high pressure-high temperature" water coolant conditions. This article first presents ALCYONE V1.4 RIA-related features and modeling. It especially focuses on recent developments dedicated on the one hand to nonsteady water heat and mass transport and on the other hand to the modeling of grain boundary cracking-induced fission gas release and swelling. This article then compares some simulations of RIA transients performed on $UO_2$-M5(R) fuel rods in flowing sodium or stagnant water coolant conditions to the relevant experimental results gained from tests performed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities. It shows in particular to what extent ALCYONE-starting from base irradiation conditions it itself computes-is currently able to handle both the first stage of the transient, namely the pellet-cladding mechanical interaction phase, and the second stage of the transient, should a boiling crisis occur. Areas of improvement are finally discussed with a view to simulating and analyzing further tests to be performed under prototypical PWR conditions within the CABRI International Program. M5(R) is a trademark or a registered trademark of AREVA NP in the USA or other countries.

• The KIPS Transactions:PartC
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• v.11C no.6 s.95
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• pp.835-842
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• 2004

In this paper, we have analyzed the MC-DS/CDMA system with input signal synchronized completely through adjustment of the gain in the PLL loop, by using the hybrid SC/MRC-(2/3) technique, which is said to one of the optimal diversity techniques under the multi-path fading environment, assuming that phase error is defined to the phase difference between the received signal from the multi-path and the reference signal in the PLL of the receiver. Also, assuming that the regarded radio channel model for the mobile communication is subject to the Nakagami-m fading channel, we have developed the expressions and performed the simulation under the consideration of various factor, in the MC/DS-CDMA system with the hybrid SC.MRC-(2/3) diversity method, such as the Nakagami fading index(m), $the\;number\;of\;paths\;(L_p),$ the number of hybrid SC.MRC-(2/3) $diversity\;branches\;(L,\;L_c),$ the number of users (K), the number of subcarriers (U), and the gain in the PLL loop. As a result of the simulation, it has been confirmed that the performance improvement of the system can be achieved by adjusting properly the PLL loop in order for the MC/DS-CDMA system with the hybrid SC/MRC-(2/3) diversity method to receive a fully synchronized signal. And the value of the gain in the PLL loop should exceed 7dB in order for the system to receive the signal with prefect synchronization, even though there might be a slight difference according to the values of the fading index and the spread processing gain of the subcarrier.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.611-618
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• 2018

In this study, numerical analysis of solid-liquid two-phase flow was conducted as a preliminary step to analyze the flow characteristics of drilling fluid using the commercial CFD code, ANSYS CFX 14.5. The homogeneous model and separated flow model were used to simulate solid-liquid two-phase flow phenomena. In the separated flow model, Gidaspow's drag force model was applied with the kinetic theory model was applied for solid particles. The validity of the numerical model used in this study was verified based on the published experimental results. Numerical analysis was carried out for volume fractions of 0.1 to 0.5 and velocities of 1 to 5 m/s in a horizontal tube with a diameter of 54.9 mm and a length of 3 m. The Pressure drop and volume fraction distribution of solid particles were confirmed. The pressure drop was predicted using the homogeneous model and separated flow model within the MAE of 17.04 % and 8.98 %, respectively. A high volume fraction was observed in the lower part of the tube, and the volume fraction decreased toward the upper part. As velocity increased, variations in volume fraction distribution at varying heights were decreased, and the numerical results predicted these flow characteristics well.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.139-144
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• 2013

A computer program has been developed to estimate time-domain electromagnetic (EM) responses for a onedimensional model with multiple source and receiver dipoles that are finite in length. The time-domain solution can be obtained by applying an inverse fast Fourier transform (FFT) to frequency-domain fields for efficiency. Frequency-domain responses are first obtained for 10 logarithmically equidistant frequencies per decade, and then cubic spline interpolated to get the FFT input. In the case of phases, the phase curve must be made to be continuous prior to the spline interpolation. The spline interpolated data are convolved with a source current waveform prior to FFT. In this paper, only a step-off waveform is considered. This time-domain code is verified with an analytic solution and EM responses for a marine hydrocarbon reservoir model. Through these comparisons, we can confirm that the accuracy of the developed program is fairly high.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1656-1662
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• 2013

The ternary phase $EuZn_xIn_{4-x}$ has been identified as the main product of reactions of Eu, Zn, and In by using the In-flux method and characterized by both powder and single-crystal X-ray diffraction. The structure belongs to the common $BaAl_4$-type (tetragonal space group I4/mmm, Pearson code tI10) with lattice parameters of a = 4.5610(9) ${\AA}$, c = 12.049(3) ${\AA}$ for composition $EuZn_{1.10(12)}In_{2.90}$ and a = 4.5463(3) ${\AA}$, c = 12.028(2) ${\AA}$ for composition $EuZn_{1.18(2)}In_{2.82}$, respectively. In this structure, the Eu atoms are situated at the center of 18-vertex Fedorov polyhedra made of Zn and In atoms, where the 4d site is preferentially occupied by In and the 4e site is occupied by randomly mixed Zn and In atoms. Theoretical investigations using tight-binding linear muffintin orbital (TB-LMTO) method provide rationale for the observed site preferences and suggest potentially wider homogeneity range than the experimentally established for $EuZn_xIn_{4-x}$ ($x{\approx}1.1$).

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.12.1-12.1
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• 2009

Nano-hydroxyapatite (N-HAp)has shown the pivotal role in producing bone-regenerative materials since it has similarity to natural bone minerals in terms of size, morphology, and the composition. Currently, the combination of biopolymers and N-HAp is recognizedas an attractive approach in generating hybrid scaffolds for bone tissueengineering. Surface engineering is an important issue since it determines whether cells can effectively adhere and proliferate on porous scaffolds. We aim to develop a synthetic approach to porous 3D scaffolds by immobilizing N-HAp on pore surfaces. The discrete nano-level anchoring of N-HAp on the scaffold pore surface is achieved using surface-repellent stable colloidal N-HAp with surface phosphate functionality. This rational surface engineering enables surface-anchored N-HAp to express its overall intrinsic bioactivity,since N-HAp is not phase-mixed with the polymers. The porous polymer scaffolds with surface-immobilized N-HAp provide more favorable environments thanconventional bulk phase-mixed polymer/N-HAp scaffolds in terms of cellular interaction and growth. In vitro biological evaluation using alkalinephosphatase activity assay supports that immobilized N-HAp on pore surfaces of polymer scaffolds contributed to the more enhanced in vitro osteogenicpotential. Besides, the scaffolds with surface-exposed N-HAp provide favorable environments for enhanced in vivo bone tissue growth, estimated by characteristic biomarkers of bone formation such as collagen. The results suggest that newly developed hybrid scaffolds with surface-immobilized N-HApmay serve as a useful 3D substrate with pore surfaces featuring excellent bonetissue-regenerative properties. Acknowledgement. This research was supported by a grant (code #: 2009K000430) from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Education, Science and Technology, Korea.

• Korean Journal of Construction Engineering and Management
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• v.1 no.2 s.2
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• pp.53-62
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• 2000

A concrete element is obtained through multi-steps, and its quality is affected by site conditions and control constituents of procedures. In these regards, in order to assure designed qualities of concrete and associated materials of the element good quality control method is necessary in various procedures. The existing quality control measures do not satisfy the requirements for the quality control activities at each production step. This study provides a more effective checklist for each phase of concrete work, which improves existing quality control checklist through extensive research on current practices and surveys from expertises. This paper also proposes the application of multi-facet codes to develop a customized checklist to improve the efficiency in field practices and the effectiveness in assuring the designed performance of concrete. This study finally provides a more effective checklist for each phase of concrete work by improving usability of the developed project sensitive matric quality control checklist through application experiments on construction project sites.