• 한국전산유체공학회:학술대회논문집
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• 2002.10a
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• pp.109-113
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• 2002

Numerical analysis of aerodynamic heating for KPSAM is performed using aerodynamic heating model suitable to KPSAM, which has complex flow field resulting from the spike attached to the dome, such as large separation area and the strong shock/boundary layer interaction region around reattachment point on the dome. The aerodynamic heating model is validated and modified through the comparison between the flight test measurement and the thermal analysis results. TFD temperature sensors are installed on the dome to measure surface temperature during the flight. Computation results, obtained from the heat transfer analysis on the sensors, agree well with flight test data. The aerodynamic heating model provides heat transfer rate into surface as a boundary condition of unsteady 1D/axisymmetric thermal analysis on the missile structure. The axisymmetric thermal analysis using FLUENT is more versatile than the 1D analysis and can be applied to the heating problem related with complex structures and multi-dimensional heat transfer problems such as prediction of temperature rise at contact surface of different materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.703-704
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• 2010

The environmental tests simulating the flight condition have been performed to manufacture the high reliable safety and arming device(SAD). A motor assay in preliminary design was reinforced with the structure to resist severe vibration and shock environment, and the design change had been verified by conducting the principal environmental test again.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.15-15
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• 1998

The problem of the impingement of a sonic or a supersonic jet on a flat surface has not only wide applications but has also interesting and very complex flow phenomena. The main applications of this impinging jet include prediction of solid surface erosion, design of launcher systems, stage separation of multi-stage rocket system, V/STOL operations, thermal spray system, and manufacturing technologies of materials. Much have been learned about the supersonic impinging jet flow field but many fundamental questions have not been answered satisfactorily. The problem encompasses many facets of fluid dynamics which, in combination, present the compressibility effect and the viscous-inviscid interaction, coupled with flow separation and reattachment. What is more, there are many flow parameters that have on the impinging jet flow field, for example, Mach number, Reynolds number, pressure ratio, distance between the nozzle exit and flat plate, jet shock structure, nozzle diameter and etc. Thus the existing data on the supersonic impinging jet flow present considerable disagreement in which quantitative comparison between one result and another is often impossible.

• Archives of Pharmacal Research
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• v.19 no.3
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• pp.248-250
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• 1996

In conclusion, a series of N-Cbz-.alpha.-amono-glutarimides (1a-f), combining common structures such as N-CO-C-N and cyclic imide in a single molecule, were prepared from the (R)- or (S)-N-Cbz-glutamic acid and evaluated for their anticonvulsant activities in MES and PTZ tests in order to develope new and broad spectrum anticonvulsant. In this study, N-Cbz-.alpha.-aminoglutarimides (1) except ac and af, showed significant anticonvulsant activity in both MES and PTZ tests enough to be recommended as promising new anticonvulsant drug candidates. Now we are continuing to investigate further anticonvulsant test (quantification)for these compounds and synthesize their analogues in order to develop more active anticonvulsant and define the structure activity relationship more precisely.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1142-1147
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• 2006

A practical method for reducing the number of spot welds in automotive structures considering fatigue crack initiation life is suggested. At first, an influence index for the durability and the fatigue life of a spot weld itself is defined and then taken as the main effect of the DOE analysis. Spot welds that can be removed without serious reduction of durability through numerical experiments are selected by the results of DOE. The proposed method was applied to the shock tower and LCA(lower control arm) structure of a vehicle, which are important components in durability-related point of view.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.6 s.123
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• pp.484-490
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• 2007

A reciprocating compressor used in domestic refrigerators can be subjected to many different forms of shock. These shocks are usually experienced during transporting the products from a manufacturer to customers. The hermetic structure of this kind of compressor makes it difficult to conduct drop tests for identifying the failure mechanism and their drop behaviors. The drop/impact simulation for a reciprocating compressor has been carried out with the explicit code LS-DYNA and its validation has been experimentally verified. Simulation results are in good agreement with those of drop test. The present method of drop/impact simulation provides an efficient and powerful solution to improve the design quality and reduce the design period.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.23-26
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• 2004

A computational analysis has been conducted to investigate the detailed flow structure inside a supersonic cavity. The free stream Mach number and Reynolds number are 1.83 and $6.02\times10^5$ respectively. In the present study, the depth and width of the cavity are changed to investigate the effect of the cavity dimensions. A fully implicit finite volume scheme is applied to solve the three-dimensional, steady, unsteady, compressible, Navier-Stokes equations. The computed results are validated with the previous experimental data available. The present computation provides reasonable predictions of the cavity flow, compared with experimental results. The obtained results show that a shock wave is generated in front of the downstream edge of the cavity and the dominant frequencies of the pressure oscillations inside the cavity were obtained.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.442-447
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• 2008

A numerical analysis has been conducted to investigate and characterize the unsteadiness of flow structure and oscillatory vacuum pressure inside of a supersonic diffuser equipped to simulate the high-altitude rocket test on the ground. A physical model of concern includes a rocket motor, a vacuum chamber, and a diffuser, which have axisymmetric configurations, using nitrogen gas as a driving fluid. Emphasis is placed on investigating physical phenomena of very complex and oscillatory flow evolutions in the diffuser operating at very close to the starting condition, i.e. minimum starting condition, which is one of major important parameters in diffuser design points of view.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.193-195
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• 2011

An abrupt increase of duct cross-section is frequently encountered in pressure reducing devices, valves of internal combustion engines and in gas pipelines. Supersonic flow in a rectangular duct passing an abrupt increase of cross-section is studied numerically. The behavior of base pressure of the dead-air region at sudden enlargement of the duct is clarified. This investigation concerns the determination of the base pressure, which is independent of the size of the enlarged part. Several flow patterns are identified with different enlargements according to the ratio between the downstream ambient pressure and the upstream reservoir pressure. Base pressure and the resulting shock-structure are highly depending on the size of duct enlargement. For a given duct, base pressure tends to minimum for a particular pressure ratio. In addition, the locations of secondary separation and reattachment points of the jet plume are found with respect to different duct enlargements.

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.104-107
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• 2018

In this paper, we developed a sensor for monitoring the leakage current through the chassis of the robot. The leakage current sensor needs to be developed because it is a necessary part to prevent electric shock accidents that may occur through the chassis of a robot or an electric vehicle. This leakage monitoring sensor was developed to be mounted directly on the chassis of the robot. This sensor protects the control system from noise by discharging static and high-frequency noise that may occur in the chassis of the robot and monitors the leakage current by measuring the amount of current discharged through the ground. In this paper, a leakage monitoring sensor was developed with a simple structure using resistors, capacitors and OP-AMP, and the performance was evaluated.