• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.167-171
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• 2006

The previous models for thermal behavior in the melting furnace were deterministic, composed of such a form that if the initial input conditions are determined, the results would have been come out by using the basic heat equilibrium equations. But making the experiment by trusting the analysis results, the melted slag is fortuitously set often, because temperature variation of the melted slag in the reaction process is not point function but path function. So in this study, a transient model was developed and verified by comparing with the experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.69-74
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• 1997

In this paper we derive relations which describe the geometry and kinematics of contact between the travelling wheel and stepped comb joint. From which we can obtain the impulse, impulsive force and its time interval due to travelling wheel impact which can not be taken from Carter's model or Newland and Cassidy's. The calculated transient responses of the comb joint structure to travelling wheel impact reveals that the proposed wheel contact model and Carter's give very similar results but Newland Cassidy's model make a quite different results from the others.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.35-38
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• 2005

One of the most serious problems in KEPCO system operation is higher fault current than the SCC(Short Circuit Capacity) of circuit breaker. There are many alternatives to reduce the increased fault current such as isolations of bus ties, enhancement of SCC of circuit breaker, applications of HVDC-BTB(Back to Back) and FCL(fault current limiter). But, these alternatives have some drawbacks in viewpoints of system stability and cost. As the superconductivity technology has been developed, the resistance type HTS-FCL(High Temperature Superconductor Fault Current Limiter) can be one of the most attractive alternatives to solve the fault current problem. To evaluate the accurate transient performance of resistance type HTS-FCL, it is needed that the dynamic simulation model considering transient characteristics during quenching and recovery state. Under this background, this paper presents the EMTDC model for resistance type HTS-FCL considering the nonlinear characteristic of final resistance value when quenching and recovery phenomena by fault current injection and clearing occurs.

• Journal of computational fluids engineering
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• v.12 no.4
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• pp.44-53
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• 2007

A three-dimensional (3D) unstructured hydrodynamic solver for transient two-phase flows has been developed for a 3D component of a nuclear system code and a component-scale analysis tool. A two-fluid three-field model is used for the two-phase flows. The three fields represent a continuous liquid, an entrained liquid, and a vapour field. An unstructured grid is adopted for realistic simulations of the flows in a complicated geometry. The semi-implicit ICE (Implicit Continuous-fluid Eulerian) numerical scheme has been applied to the unstructured non-staggered grid. This paper presents the numerical method and the preliminary results of the calculations. The results show that the modified numerical scheme is robust and predicts the phase change and the flow transitions due to boiling and flashing very well.

• Journal of Korean Neurosurgical Society
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• v.65 no.2
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• pp.180-185
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• 2022

Objective : Drug-eluting stents and balloons are occasionally used to reduce restenosis in medically intractable intracranial atherosclerotic stenosis. The authors aimed to determine whether such drugs can cause neurotoxicity due to local effects in a rat model. Methods : Intra-arterial catheters were placed in the right common carotid artery of rats. Mannitol was injected to transiently open the brain-blood barrier (BBB), followed by high-dose drug (paclitaxel and rapamycin) injection. The optimal time interval of transient BBB opening for maximal drug penetration was determined to be 10 minutes. Paclitaxel and rapamycin were intra-arterially administered in various doses. All the rats were neurologically evaluated, and their brain tissues were histologically examined. Results : Neither neurological deficits nor histological abnormalities were observed in all the rats. Conclusion : Paclitaxel and rapamycin did not cause neurotoxicity in a rat model with transient BBB opening.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.6
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• pp.296-301
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• 2002

Modern power systems are very complex and to model them completely is impractical for electromagnetic transient studies. Therefore areas outside the immediate area of interest must be represented by some form of Frequency Dependent Network Equivalent (FDNE). In this paper a method for developing Frequency Dependent AC system Equivalent (FDACSE) using Z-domain rational Function Fitting is presented and demonstrated. The FDACSE is generated by Linearized Least Squares Fitting(LSF) of the frequency response of a Z-domain formulation. This 1 & 2 port FDACSE have been applied to the New Zealand South Island AC power system. The electromagnetic transient package PSCAD/EMTDC is used to assess the transient response of the 1 & 2 port FDACSE developed under different condition (linear load, fault and nonlinear loading). The study results have indicated the robustness and accuracy of 1 & 2 port FDACSE for electromagnetic transient studies.

• Steel and Composite Structures
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• v.21 no.1
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• pp.57-72
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• 2016

The Poisson ratio reduction of symmetric hygrothermal aged $[{\theta}_m/90_n]_s$ composite laminates containing a transverse cracking in mid-layer is predicted by using a modified shear-lag model. Good agreement is obtained by comparing the prediction models and experimental data published by Joffe et al. (2001). The material properties of the composite are affected by the variation of temperature and transient moisture concentration distribution in desorption case, and are based on a micro-mechanical model of laminates. The transient and non-uniform moisture concentration distribution give rise to the transient Poisson ratio reduction. The obtained results represent well the dependence of the Poisson ratio degradation on the cracks density, fibre orientation angle of the outer layers and transient environmental conditions. Through the presented study, we hope to contribute to the understanding of the hygrothermal behaviour of cracked composite laminate.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.6
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• pp.1777-1783
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• 2004

This study was conducted to determine the effects Wonjiseokchangpo-san on brain damage in transient focal cerebral ischemia. Rats were used for testing in the following three models: Morris Water Maze, Eight-Arm Radial Maze, and Histochemistry. In the Morris Water Maze Model, the Wonjiseokchangpo-san group showed significant decrease in the 3rd and 6th training session compared with the ischemia group. A retention test, in the Morris Water Maze Model, was performed on the 7th day without the escape platform. The Wonjiseokchangpo-san group showed significant increase compared to the ischemia group. In the Eight-Arm radial Maze model, the Wonjiseokchangpo-san group showed significant decrease in the error rate compared to the ischemia group. In the density of hippocampal CA1 cell of the cresyl violet-stained section, the Wonjiseokahangpo-san group showed significant increase compared to the ischemia group. These results suggest that Wonjiseokchangpo-san may have a significant protective effect on brain damage and cognitive dysfunction in transient focal cerebral ischemia.

• The Journal of Korean Medicine
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• v.26 no.2 s.62
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• pp.52-62
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• 2005

Objectives: This study was conducted to determine the effects of Geupunggibodan on brain damage in transient focal cerebral ischemia in rats. Methods: Rats were used for testing in the following three models: Morris water maze, eight-ann radial maze, and histochemistry. Results: In the Morris water maze model, the Geupunggibodan group showed significant decrease in the 3rd, 4th and 6th training sessions compared with the ischemia, group. A retention test in the Morris water maze model was performed on the 7th day without the escape platform. The Geupunggibodan group showed significant increase compared to the ischemia group. In the eight-ann radial maze model, the Geupunggibodan group showed significant decrease in the error rate compared to the ischemia group. In the density of hippocampal CA1 cell of the cresyl violet-stained section, the Geupunggibodan group showed significant increase compared to the ischemia group. Conclusions: These results suggest that Geupunggibodan may have a significant protective effect on brain damage and cognitive dysfunction in transient focal cerebral ischemia.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.487-490
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• 2010

A fluid transient analysis on the pipe network of bipropellant propulsion system is conducted through numerical parametric studies in which unsteady friction results are compared with quasi-steady friction results and also show the pressure drop results during the liquid apogee engine firing. The fluid transient analysis program has verified through comparing with the original Zielke model, the full and recursive convolution model and quasi-steady model as a reference. And the pressure drop program also has verified through comparing with results of the well-known program, EPANET2. The bipropellant propulsion system has two different fluids as fuel and oxidizer, and mostly they are hypergolic combination so that the valve opening and closing of the thrusters, that cause the pressure waves, shall take place simultaneously to get proper performance. The different physical properties of the fuel and oxidizer result in the different responsive to the same valve opening and closing. The response results may be helpful to know the characteristics of the bipropellant propulsion system and design it.