• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.290-296
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• 2018

In this study, the cold test and the numerical analysis were carried out according to the shape parameters of the test model in order to confirm the operation range of high altitude environment simulation test facility for the supersonic vehicle. The blockage ratio, angle and length ratio were considered as the design parameters. The blockage rate is expected to be limited in the region of more than 40% due to the normal shock and expansion fan. It was confirmed that the angle of model should be selected at the size of 45 degrees or less due to the influence of the strong shock wave. There was no difference in performance between the lengths of 8 times the model diameter. Finally, we obtained the performance database according to the shape parameters of the conical test model and confirmed the operable range of the semi-freejet type high altitude environment simulation test facility.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.485-488
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• 2007

Riverbank filtration is a kind of artificial aquifer recharge for the fresh water supply. By construction of several production wells penetrating the riverbank, surface water withdrawn from the river would pass riverbed. This extracted water is well known to be cooler than surface water in summer and warmer than surface water in winter, showing more constant water temperature. This characteristic of extracted water is applied to geothermal energy utilization. Prediction of the annual temperature variation of filtrated water is the major concern in this study. In Daesan-myeon, Changwon-si, Gyeongsangnam-do, South Korea, riverbank filtration facility has been on its operation for municipal water supply and thermal energy utilization since 2006. Appropriate hydraulic and thermal properties were estimated for flow and heat transfer modeling with given pumping rate and location. With the calibrated material properties and boundary conditions, we numerically reproduced measured head and temperature variation with acceptable error range. In the numerical simulation, the change of saturation ratio and river stage caused by rainfall was calculated and the resulting variation of thermal capacity and thermal conductivity was considered. Simulated temperature profiles can be used to assess the possible efficiency of geothermal energy utilization using riverbank filtration facility. Influence of pumping rate, pumping location on the extracted water temperature will be studied.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.217-225
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• 2023

This study analyzed the effect of flood level reduction in the case of creating and operating offline storage for the Jangdong district, which can be used as a flood buffer space for the Geumgang River, through one-dimensional unsteady flow numerical simulation. In particular, the sensitivity analysis of changes in the height and width (length) of transverse weirs on flood level changes was performed to provide quantitative information necessary for flood control facility (embankment) design. As a result of analyzing the flood control effect of the offline storage based on the peak flood discharge and level, spatially, the flood control effect at the planned flood buffer space site and the downstream end was confirmed, and it was confirmed that the flood reduction effect at the downstream occurred the most. By design conditions of the transverse overflow weir, the greatest flood reduction effect was found under the condition that the overflow weir height based on the 50-year frequency flood level and the transverse overflow weir width (length) of 125 m were considered. The effect of delaying the time to reach the maximum flood due to the operation of the offline storage site was also presented based on unsteady flow modeling.

• Nuclear Engineering and Technology
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• v.35 no.3
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• pp.179-190
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• 2003

The multiple steam generator tube rupture (SGTR) event scenario with available safety systems was experimentally and analytically evaluated. The experiment was conducted on the large scaled test facility to simulate the multiple SGTR event and investigate the effectiveness of operator actions. As a result, it indicated that the opening of pressurizer power operated relief valve was significantly effective in quickly terminating the primary-to-secondary break flow even for the 6.5 tubes rupture. In the analysis, the recent version of RELAP5 code was assessed with the test data. It indicated that the calculations agreed well with the measured data and that the plant responses such as the water level and relief valve cycling in the damaged steam generator were reasonably predicted. Finally, sensitivity study on the number of ruptured tubes up to 10 tubes was performed to investigate the coolant release into atmosphere. It indicated that the integrated steam mass released was not significantly varied with the number of ruptured tubes although the damaged steam generator was overfilled for more than 3 tubes rupture. These findings are expected to provide useful information in understanding and evaluating the plant ability to mitigate the consequence of multiple SGTR event.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3027-3032
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• 2007

To understand the complex phenomena performed in steam explosion, the fast and global measurement of the steam distribution is imperative for this extremely rapid transient stimulation of the bubble breakup and coalescence due to turbulent eddies and shock waves. TROI, the experimental facility requests more robust sensor system to meet this requirement. In Europe, researchers are prefer a X-ray method but this method is very expensive and has limited measurement range. There is an alternative technology such as ECT. Because of TROI's geometry, however, we need axial tomography method. This paper reviews image reconstruction algorethms for axial tomography, including Tikhonov regularization and iterative Tikhonov regularization. Axial tomography method is examined by simulation and experiment for typical permittivity distributions. Future works in axial tomography technology is discussed.

• Journal of Korean Society of Water and Wastewater
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• v.24 no.2
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• pp.211-217
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• 2010

In order to suggest the methodology for achieving anti-vortex within multi pump intake well, the field test and CFD(Computational Fluid Dynamics) simulation were conducted. The filed test were carried out for domestic W_multi pump intake well according to usual operation condition through the naked observation. From the results, operating #4, #5, #8 and 9# pumps, the vortex and swirl occurred above #4 and #9 intake pipe within two wells. For qualitative analysis, a commercial CFD code, using sump model, was used to predict the vortex generation within the selected pump intake facility accurately. The analysed results by CFD show that the vortex structure and location are in accordance with the results of the field test.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1011-1016
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• 2010

It is an important issue to electric power system operations that it can reliably supply large-capacity power to consumption area as due to increasing power demand growth. For this purpose, The FACTS equipment based on Power IT technology with the existing mechanical compensators has been applied to power system. Therefore we suggest on this paper that a plan for coordination control of multiple power compensation equipment in order to increase the utilization of each facility and secure operation margin capacity. As the result of simulation, it is possible to cope actively with a suddenly changed power system. This helps greatly for the voltage stability and supply reliability in a suddenly changed power system.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.172-175
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• 2008

In the last five years, 45 people died and 104 were wounded because of carbon monoxide poisoning accident. CO poisoning accident is higher than any other gas accident in the rate of deaths/incidents. Most of these CO poisoning accidents were caused by defective exhaust tube in the old gas boiler and multi-use facility. In this study, the spread of CO gas released from leakage hole of exhaust tube was analyzed by computational flow modeling and concentration measuring test. CO gas leaked form exhaust tube in a building was highest concentrated near the ceiling and formed the circular currents along the walls. Through these experiments and simulation, the reasonable installation location of CO alarm was made certain and suggested.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.50-51
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• 2017

The Urban-type building is an building that it relaxed the construction standard and subsidiary facility standard. The most of the urban-type buildings are pilotis, the main case of representing these building's fire risk is the Uijeongbu fire this study investigated to piloti urban type housing risk on the basis of Uijeongbu fire, and we checked structural problem that unable to escape from the rooftop inside the piloti. also, there was confirmed limit to the evacuation of the occupants because the smoke was rapidly transferred to the top layer through inside the electric duct. and when we analyzed smoke flow use of Fire simulation, it was confirmed Available Safety Egress Time that is four minutes of CO.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.511-521
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• 2010

This paper presents a new algorithm to determine accurate bus-wise transmission loss allocation utilizing path-integrals dictated by the transaction strategy. For any transaction strategy, the total sum of the allocated transmission losses of all buses is equal to the actual loss given by the AC power-flow calculation considering the distributed slack. In this paper, the bus-wise allocation of the transmission loss is calculated by integrating the differential loss along a path determined by the transaction strategy. The proposed algorithm is also compared with Galiana's method, which is the well-known transmission loss allocation algorithm based on integration. The performance of the proposed algorithm is evaluated by case studies carried out on the WSCC 9-bus, IEEE 14-bus, New England 39-bus, and IEEE 118-bus systems. The simulation results show that the proposed algorithm is fast and accurate with a large step size.