• Journal of KIBIM
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• v.12 no.4
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• pp.1-18
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• 2022

New Fabrication Facility (FAB) construction is performed with Building Information Modeling (BIM) based design. The BIM design data keep updated during the FAB construction. To improve fast-track construction management, a Fabrication Facility Augmented Reality (FABAR) was developed. This study introduces a FABAR system development process and shows performance evaluation results of the FABAR prototype system. The FABAR is implemented with three major modules: Augmented Reality (AR) visualization unit (Room-box) to transfer big BIM data to AR data, AR registration and tracking unit to match AR with real scape and to keep AR coordination in real, and AR data management unit to enhance usability. The prototype performance results were as follows: visualization of design BIM data via AR within 24 hours, precise AR registration and tracking registration, and appropriate usability to support FAB construction management at site. The results indicate that the FABAR is applicable for FAB construction management. Especially, the BIM data transformation method using Room-box in this study signifies a new construction management approach using fluctuating BIM design data in the fast track construction condition.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1213-1224
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• 2024

The liquid lead-bismuth cooled fast reactor has been in a single-phase, low-pressure, and high-temperature state for a long time during operation. Considering the requirement of calculation efficiency for long-term transient accident calculation, based on a homogeneous hydrodynamic model, one-dimensional heat conduction model, coolant flow and heat transfer model, neutron kinetics model, coolant and material properties model, this study used the fully implicit difference scheme algorithm of the convection-diffusion term to solve the basic conservation equation, to develop the transient analysis program NUSOL-LMR 2.0 for the lead-bismuth fast reactor system. The steady-state and typical design basis accidents (including reactivity introduction, loss of flow caused by main pump idling, excessive cooling, and plant power outage accidents) for the ABR have been analyzed. The results are compared with the international system analysis software ATHENA. The results indicate that the developed program can stably, accurately, and efficiently predict the transient accident response and safety characteristics of the lead-bismuth fast reactor system.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.821-830
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• 2001

H.323 proposes to use Mobile IP and H.323 ad hoc conference signaling to provide Handoff function to a mobile terminal. But H.323 ad hoc conference signaling has a drawback. It requires an H.323 endpoint to do a complex conference signaling which makes inter-operability between H.323 endpoints difficult and takes the longer signaling time. In this paper, we propose an Handoff signaling using H.323 rerouting(Third party initiated Pause and Rerouting). H.323 rerouting signaling only requires an H.323 endpoint to do H.323 basic signaling in reestablishing media channel, and makes inter-operability more easier and provides the faster Handoff. To do this, our H.323 GK has derived H.245 control channel using tunneling for all H.323 calls including the fast connect calls which enable endpoints communicate each other if they don\`t have H.245 control channel. In order to evaluate the performance of the proposed signaling, we have conducted an experiment that compares a call transfer signaling using H.323 rerouting with ad hoc conference signaling in inter-operability and signaling delay. The results of our experiment shows that the call transfer signaling can inter-operate with four H.323 endpoints among five H.323 endpoints of other vendors and reduces the signaling delay average 1.4 sec.

• Journal of computational fluids engineering
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• v.18 no.4
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• pp.25-34
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• 2013

A numerical study of a laminar natural convection of the CuO-water nanofluid in a square cavity using the Buongiorno's nonhomogeneous model is presented. All the governing equations including the volume fraction equation are discretized on a cell-centered, non-uniform grid employing the finite-volume method with a primitive variable formulation. Calculations are performed over a range of Rayleigh numbers and volume fractions of the nanopartile. From the computed results, it is shown that both the homogeneous and nonhomogeneous models predict the deterioration of the natural convection heat transfer well with an increase of the volume fraction of nanoparticle at the same Rayleigh number, which was observed in the previous experimental studies. It is also shown that the differences in the computed results of the average Nusselt number at the wall between the homogeneous and nonhomogeneous models are very small, and this indicates that the slip mechanism of the Brown diffusion and thermophoresis effects are negligible in the laminar natural convection of the nanofluid. The degradation of the heat transfer with an increase of the volume fraction of the nanoparticle in the natural convection of nanofluid is due to the increase of the viscosity and the decrease of the thermal expansion coefficient and the specific heat. It is clarified in the present study that the previous controversies between the numerical and experimental studies are owing to the different definitions of the Nusselt number.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1217-1225
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• 2010

The possibility of a sodium-water reaction occurring in a conventional single-wall-tube steam generator in an SFR is a major problem. To improve the reliability of a steam generator, a double-wall-tube steam generator that can reduce the possibility of the occurrence of a sodium-water reaction is being developed. Current developments are focusing on improving the heat-transfer capability of a double-wall tube; further, the development of a leak-detection method to detect the occurrence of a sodium-water reaction during the reactor operation is also underway. In this study, new concepts, which will solve the above-mentioned problems, have been developed. Accordingly, a double-wall tube has been designed, fabricated, and mechanically tested for the purpose.

• Journal of Powder Materials
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• v.23 no.6
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• pp.458-465
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• 2016

A $TiO_2$/CNT nanohybrid photocatalyst is synthesized via sol-gel route, with titanium (IV) isopropoxide and multi-walled carbon nanotubes (MWCNTs) as the starting materials. The microstructures and phase constitution of the nanohybrid $TiO_2$/CNT (0.005wt%) samples after calcination at $450^{\circ}C$, $550^{\circ}C$ and $650^{\circ}C$ in air are compared with those of pure $TiO_2$ using field-emission scanning electron microscopy and X-ray diffraction, respectively. In addition, the photocatalytic activity of the nanohybrid is compared with that of pure $TiO_2$ with regard to the degradation of methyl orange under visible light irradiation. The $TiO_2$/CNT composite exhibits a fast grain growth and phase transformation during calcination. The nanocomposite shows enhanced photocatalytic activity under visible light irradiation in comparison to pure $TiO_2$ owing to not only better adsorption capability of CNT but also effective electron transfer between $TiO_2$ and CNTs. However, the high calcination temperature of $650^{\circ}C$, regardless of addition of CNT, causes a decrease in photocatalytic activity because of grain growth and phase transformation to rutile. These results such as fast phase transformation to rutile and effective electron transfer are related to carbon doping into $TiO_2$.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3864-3871
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• 2024

In case of a hypothetical severe accident in a Sodium-cooled Fast Reactor (SFR), coolability of the debris bed in the post-accident phase plays a vital role in mitigating the accident and ensuring the structural integrity of the reactor vessel. Few numerical studies are reported in literature, in which the boiling heat transfer in debris bed is expressed as equivalent heat conduction using similarity law between heat conduction and two-phase heat transfer. However, these studies assumed steady state mass conservation for the boiling zone and neglected the gravity force. Hence, a detailed study has been carried out for various particle sizes and porosities of SFR debris to investigate the influence of above considerations. The effect of gravity on debris bed coolability is studied using steady state model of Lipinski, which showed that gravity has a non-negligible effect, for particle size of 0.3 mm and porosity of 0.5. However, the gravitation force was found to have a negligible effect in dryout heat flux estimation for the bottom cooled configuration. A transient numerical model is developed for simulating the boiling phenomena in debris beds and validated with the published experimental results. The assumption of steady state mass conservation is verified by carrying out transient analysis, which indicated early prediction of the dryout inception. For time dependent heat generation case, the unsteady mass conservation predicted higher DHF compared to constant heat generation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.959-962
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• 2005

Recently, business integration and interoperability of between the heterogeneous applications are requested by rapid growth of web. Web Services that self-contained for platform and programming language is appeared used to XML of standard data format. Such amid Fast Web Services attract attention at fields necessary to bring rapid communication like Mobile and RFID. In this paper, we inquired about ASN.1 of ITU-T and IS0/IEC standard that a central role of data transform. And we studied encoding process of between ASN.1 and XML for transform SOAP massage of a massage transfer mode of Web Services to binary data.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.79-85
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• 2006

Radiative heat transfer is very important in many combustion systems since they are operated in high temperature. Fluid flows in most of the combustion systems are turbulent to promote fast mixing of the hydrocarbon fuel and oxidant. Major combustion products are $CO_2$ and $H_2O$. The turbulent flow is modeled by using the standard ${\kappa}-{\epsilon}$ model and the radiation transfer is modeled by using the discrete ordinates method where the radiative gas properties are calculated by using the weighted sum of gray gases model with a gray gas regrouping(WSGGM-RG). Effect of the radiation on the combustion characteristics in a three-dimensional rectangular enclosure is studied by changing the equivalence ratio. Results show that the radiation plays a significant role on the heat transfer in the combustion systems by resulting in a temperature drop of 16% as compared to that obtained without radiation. The equivalence ratio also affects the combustion by different contribution of the radiative transfer with different gas compositions.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.50-52
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• 2008

We have limited the transfer power to capital area below a certain level which is called "The Capital Area Transfer Power Limit", and calculated on every Thursday for the application next week. This level is very important in our network operation, because if this level is not set properly, our power network can be fallen under great danger in case of a fault among the transfer power line. But the calculation procedure for the limit level is so complicated and iterative that it mace us spend much time and do much work. So, when a sudden trip of the related facility to the limit level we can't recalculate the limit level fast enough. And this can drop our network reliability below our standards, therefore our network can be dangerous. To avoid this kind of problems, we have figured out a method to calculate simply the limit level. That method uses the index related to the level. We think this method can make short of the calculation procedures for the level. This paper deals with the simplified method for the calculation of the level limit.