• Journal of Energy Engineering
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• v.21 no.4
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• pp.419-426
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• 2012

A transient, three-dimensional, two-phase flow analysis code, CUPID, has been developed in KAERI. In this work, we performed a preliminary analysis using the CUPID code to investigate the thermal-hydraulic behavior of the moderator in the Calandria vessel of a CANDU reactor. At first, we validated the CUPID code using the three experiments that were performed at Stern Laboratories Inc. To avoid the complexity to generate computational mesh around the Calandria tube bundles, a porous media approach was applied for the region. The pressure drop in the porous media zone was modeled by an empirical correlation. The results of the calculations showed that the CUPID code can predict the mixed flow pattern of forced and natural convection inside the Calandria vessel very well. Thereafter, the analysis was extended to a two-phase flow condition. Also, the local maximum temperature in the Calandria vessel was plotted as a function of the injection flow rate, which may be utilized to predict the local subcooling margin.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.9
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• pp.1149-1164
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• 1997

In this study, the applicability of the RNG k-.epsilon. model to the analysis of the complex flows is studied. The governing equations based on a non-orthogonal coordinate formulation with Cartesian velocity components are used and discretized by the finite volume method with non-staggered variable arrangements. The predicted results using the RNG k-.epsilon. model of three complex flows, i.e., the flow over a backward-facing step and a blunt flat plate, the flow around a 2D model car are compared to these from the standard k-.epsilon. model and experimental data. That of the unsteady axisymmetric turbulent flow within a cylinder of reciprocating model engine including port/valve assembly and the spray characteristics within a chamber of direct injection model engine are compared to these from the standard k-.epsilon. model and experimental data. The results of reattachment length, separated eddy size, average surface pressure distribution using the RNG k-.epsilon. model show more reasonable trends comparing with the experimental data than those using the modified k-.epsilon. model. Although the predicted rms velocity using the modified k-.epsilon. model is lower considerably than the experimental data in incylinder flow with poppet valve, predicted axial and radial velocity distributions at the valve exit and in-cylinder region show good agreements with the experimental data. The spray tip penetration predicted using the RNG k-.epsilon. model is more close to the experimental data than that using the modified k-.epsilon. model. The application of the RNG k-.epsilon. model seems to have some potential for the simulations of the unsteady turbulent flow within a port/valve-cylinder assembly and the spray characteristics over the modified k-.epsilon. model.

• Tunnel and Underground Space
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• v.15 no.2 s.55
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• pp.145-156
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• 2005

MODFLOW, 3-D finite difference code, is widely used to model groundwater flow and has been used to assess the effect of excavations on the groundwater system due to construction of subways and mountain tunnels. The results of numerical analysis depend on boundary conditions, initial conditions, conceptual models and hydrogeological properties. Therefore, its accuracy can only be enhanced using more realistic and field oriented input parameters. In this study, SA(simulated annealing) was used to integrate hydraulic conductivities from a few of injection tests with geophysical reference images. The realizations of hydraulic conductivity random field are obtained and then groundwater flows in each geostatistically equivalent media are analyzed with a numerical simulation. This approach can give probabilistic results of groundwater flow modeling considering the uncertainty of hydrogeological medium. In other words, this approach makes it possible to quantify the propagation of uncertainty of hydraulic conductivities into groundwater flow.

• Journal of the Korean Chemical Society
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• v.44 no.3
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• pp.212-219
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• 2000

An absorption spectrometry coupled with flow injection analysis has been developed and tested for the analysis of the Cr$_2O_7^{2-}$/Nn$O_4^-$ mixtures. Even though one has to inject the sample twice into the FIA system and the process of the sample treatment is required to completely destroy the Mn$O_4^-$ ion for the analysis of the Cr$_2O_7^{2-}$ ion, the new method has definite advantages over the current method. It utilizes only a single analytical wavelength (570 nm) and enables one to construct calibration curves which accurately follow the Beer's law over wide ranges of analytical concentrations of both ions ($2.0{\times}10^{-6}$M∼$8.0{\times}10^{-3}$M for Cr$_2O_7^{2-}$ ion, $2.0{\times}10^{-6}$M∼$4.0{\times}10^{-3}$M for MnO4- ion).

• Composites Research
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• v.27 no.2
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• pp.52-58
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• 2014

Short fiber reinforced composites manufactured by injection molding have diverse fiber orientations variable with measuring positions even in the same specimen, which is caused by the flow induced fiber orientation. Fiber orientations considerably affect the mechanical and thermal properties of final composite products. In this study, fiber orientation of injection molded carbon fiber reinforced PA6/PPO composite was measured at several points of the specimen by optical microscopy analysis and the corresponding izod impact strength, coefficients of thermal expansion (CTE) were also measured to investigate the influence of local fiber orientation on the mechanical and thermal properties. Izod impact strength where fiber was perpendicular to the direction of crack propagation was higher than where fiber was parallel to the direction, which could be explained be the impact resistance reinforcing mechanism by fiber orientation. CTE was also lower where fiber was parallel to the measurement direction of CTE than where fiber was perpendicular to the direction, which could be also explained by the dimensional stability mechanism by fiber orientation.

• Biomolecules & Therapeutics
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• v.16 no.3
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• pp.203-209
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• 2008

The aim of this study was to investigate the hepatoprotective effect of $ACTIValoe^{(R)}$ N-931 complex, a mixture of Aloe vera and Silybum marianum, against acute liver injuries. Acute liver damages were induced by intraperitoneal injection of galactosamine (GalN, 700 mg/kg), naphthylisothiocyanate (ANIT, 40 mg/kg) and ethionine (500 mg/kg). $ACTIValoe^{(R)}$ N-931 (85, 170 and 340) was administered orally 48 h, 24 h, 2 h before and 6 h after the injection of hepatotoxins. At 24 h after GalN treatment the levels of serum aminotransferases and hepatic lipid peroxidation were significantly elevated, whereas hepatic glutathione, serum triglyceride (TG) and total cholesterol were decreased. These changes were attenuated by $ACTIValoe^{(R)}$ N-931 complex. The serum aminotransferase activities and total bilirubin significantly increased at 48 h after ANIT treatment, but were attenuated by $ACTIValoe^{(R)}$ N-931 complex. The bile flow was lower after ANIT treatment, which was restored by $ACTIValoe^{(R)}$ N-931 complex. $ACTIValoe^{(R)}$ N-931 complex reduced the ethionine-induced elevated hepatic TG contents. Histopathological analysis revealed that signs of liver injury were prominent at 24 h as result of ethionine injection, demonstrated by extensive areas of fatty change and microvesicular steatosis were observed around cells. These changes were attenuated by $ACTIValoe^{(R)}$ N-931 complex. Our results suggest that the $ACTIValoe^{(R)}$ N-931 complex has a protective effect on acute liver injury.

• The Korean Journal of Nuclear Medicine
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• v.20 no.2
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• pp.53-59
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• 1986

Radionuclide angiography of the liver and spleen with rapid bolus injection of 5 mCi of $^{99m}Tc-Sn-phytate$ was performed for evaluation of dynamic flow change of the liver in 5 normal subjects and 11 patients with diffuse hepatocellular diseases. And quantification of hepatic arterial index (HAI) was generated from those TACs of the liver and compared with HAI generated from hepatic TAC with injection of $^{99m}Tc-TcO_4^-$ as previously reported method by former investigators, 67 patients with diffuse hepatocellular diseases undergoing hepatic scintigraphy were also evaluated by 2 minutes-hepatosplenic scintiangiography with 5 mCi of $^{99m}Tc-phytate$ and followed injection of 7 mCi of $^{99m}Tc-TcO_4^-$. Those heaptic and splenic TACs were analysed and compared with HAIs of 99m Tc-phytate for evaluation of relative change (%) of count at 30 seconds and 1 minuite after peaks of rapid influx phase to the peaks (100%) in T ACs of $^{99m}Tc-phytate$ and at 1 minuite and 3 minuites after in 5 minuite-TAC of $^{99m}Tc-TcO_4^-$. Correlation between HAIs with $^{99m}Tc-phytate$ and $^{99m}Tc-TcO_4^-$ was highly significant (R=0,984, P=0), and there was most significant and useful correlation (R=0,708, p<0.0001) between HAI and splenic TAC generated by $^{99m}Tc-phytate$.

• Journal of the Korean GEO-environmental Society
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• v.10 no.2
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• pp.61-68
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• 2009

This paper presents the numerical investigation for the hydraulic behavior of a fractured rock mass with a hydromechanical interaction which may be considered during the in-situ hydraulic injection test. These experiments consist in a series of flow meter injection tests for fractures existing along an open hole section installed in a borehole, and experimental results are applied for testing a numerical model developed to the analysis and prediction of such hydromechanical interactions. Field experimental results show that conductive fractures form a dynamic and interdependent network, that individual fractures cannot be adequately modeled as independent systems, that new fluid intaking zones generate when pore pressure exceeds the minimum principal stress magnitude in that borehole, and that pore pressures much larger than this minimum stress can be further supported by the circulated fractures. In this study, these characteristics are investigated numerically how to influence the morphology of the natural fracture network in a rock mass by using a discrete fracture ntework model.

• Tunnel and Underground Space
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• v.23 no.6
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• pp.572-580
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• 2013

In this case study, I examined the microseismic safety management system of Deep Heat Mining Basel (DHMB) as EGS Geothermal Project which was conducted in Basel, Switzerland. EGS Geothermal Power projects which require induced seismic event by stimulation for creation of EGS geothermal reservoir have to be controlled pressure and flow rate of stimulation by establishment of microseismic safety management system. Traffic light system and Communication response procedure of DHMB project to respond step by step corresponding microseismic event intensity through continuous monitoring during stimulation period have been managed and established in advance of stimulation. However, the project was discontinued because of an earthquake to occur larger than expected one due to post-injection seismicity occurring in the geothermal reservoir after completion of injection for stimulation. The result of post analysis, Real-time traffic light system was verified to need a establishment of new microseismic safe management system to be considered post-injection seismicity phenomenon.

• Journal of Powder Materials
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• v.21 no.3
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• pp.215-221
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• 2014

Translucent alumina is a potential candidate for high temperature application as a replacement of the glass or polymer. Recently, due to the increasing demand of high power light emitting diode (LED), there is a growing interest in the translucent alumina. Since the translucent property is very sensitive to the internal defect, such as voids inside or abnormal grain growth of sintered alumina, it is important to fabricate the defect-free product through the fabrication process. Powder injection molding (PIM) has been commonly applied for the fabrication of complex shaped products. Among the many parameters of PIM, the flowability of powder/binder mixture becomes more significant especially for the shape of the cavity with thin thickness. Two different positions of the gate were applied during PIM using the disc type of die. The binder was removed by solvent extraction method and the brown compact was sintered at $1750^{\circ}C$ for 3 hours in a vacuum. The flowability was also simulated using moldflow (MPI 6.0) with two different types of gate. The effect of the flowability of powder/binder mixture on the microstructure of the sintered specimen was studied with the analysis of the simulation result.