• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.62-70
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• 2002

Methodology of predicting steady performance of gas turbine engine from transient test data was explored to develop an economic performance test technique. Discrepancy of transient performance from steady performance was categorized as dynamic, thermal and aerodynamic transient effects. Each effect was mathematically modeled and quantified to provide correction factors for calculating steady performance. Engine performance tests were conducted at Altitude Engine Test Facility of KARI. The influence of engine inlet/outlet condition change on engine performance was corrected firstly, and then steady performance was predicted from the correction factors. The result was compared with steady performance test data. This correction method showed an acceptable level of precision, 3.68% difference of fuel flow.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.675-680
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• 2004

In this study, a turbine simuiator is designed and manufactured to investigate the transient response of an actual turbine. The rotor mass and bearing stiffness is reduced to 1/140 of its actual turbine. The dynamic characteristics of turbine simulator are similar to those of the actual turbine. The turbine simulator is excited by an electro-magnetic type exciter in the form of half sine wave. Duration time is con☞oiled by Sms, 10ms, and Isms, and maximum acceleration is applied by 3g. Foundation excitation test is performed in stationary condition and rotating condition(6000rpm). The test results can be used to verify the validif of the theoretical afproach for transient analysis of actual turbine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.821-826
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• 2011

The turbopump+gas generator (TP+GG) coupled test for the liquid rocket engine development was performed. By comparing the results of a engine startup transient analysis with this test results, the verification of the analysis model was performed. From this, as to the analysis of the engine startup, the method calculating the pressure ratio of the turbine during the initial stage of startup was improved. And a fact that the transient heat transfer phenomenon between the working fluid and the solid parts of turbine effects to the calculation of turbine pressure ratio and consequentially to the startup analysis was revealed.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.1
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• pp.40-46
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• 2000

In this paper, a transient identification based on a Hidden Markov Model (HMM) has been suggested and evaluated experimentally for the classification of transients in the dynamic process. The transient can be identified by its unique time dependent patterns related to the principal variables. The HMM, a double stochastic process, can be applied to transient identification which is a spatial and temporal classification problem under a statistical pattern recognition framework. The HMM is created for each transient from a set of training data by the maximum-likelihood estimation method. The transient identification is determined by calculating which model has the highest probability for the given test data. Several experimental tests have been performed with normalization methods, clustering algorithms, and a number of states in HMM. Several experimental tests have been performed including superimposing random noise, adding systematic error, and untrained transients. The proposed real-time transient identification system has many advantages, however, there are still a lot of problems that should be solved to apply to a real dynamic process. Further efforts are being made to improve the system performance and robustness to demonstrate reliability and accuracy to the required level.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2477-2487
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• 2021

To improve safety analysis technology for a nuclear reactor containment considering an interaction between a reactor coolant system (RCS) and containment, this study aims at an experimental investigation on the integrated simulation of the RCS and containment, with an integral effect test facility, ATLAS-CUBE. For a realistic simulation of a pressure and temperature (P/T) transient, the containment simulation vessel was designed to preserve a volumetric scale equivalently to the RCS volume scale of ATLAS. Three test cases for a steam line break (SLB) transient were conducted with variation of the initial condition of the passive heat sink or the steam flow direction. The test results indicated a stratified behavior of the steam-gas mixture in the containment following a high-temperature steam injection in prior to the spray injection. The test case with a reduced heat transfer on the passive heat sink showed a faster increase of the P/T inside the containment. The effect of the steam flow direction was also investigated with respect to a multi-dimensional distribution of the local heat transfer on the passive heat sink. The integral effect test data obtained in this study will contribute to validating the evaluation methodology for mass and energy (M/E) and P/T transient of the containment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1448-1453
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• 2012

In this study, we carried out transient radiation test for identify failure situation by a transient radiation effect on operational amplifier devices. This experiments were carried out using a 60 MeV electron beam pulse of the LINAC(Linear Accelerator) facility in the Pohang Accelerator Laboratory. In this test, we has found that a serious failure as a burn-out effect due to overcurrent on the partial electronic devices.

• Nuclear Engineering and Technology
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• v.41 no.3
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• pp.295-306
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• 2009

The subchannel grade void distributions in the NUPEC (Nuclear Power Engineering Corporation) BFBT (BWR Full-Size Fine-Mesh Bundle Tests) facility were evaluated with the subchannel analysis code MATRA and the system code MARS. Fifteen test series from five different test bundles were selected for an analysis of the steady-state subchannel void distributions. Two transient cases, a turbine trip without a bypass as a typical power transient and a re-circulation pump trip as a flow transient, were also chosen for this analysis. It was found that the steady-state void distributions calculated by both the MATRA and MARS codes coincided well with the measured data in the range of thermodynamic qualities from 5% to 25%. The results of the transient calculations were also similar and were highly feasible. However, the computational aspects of the two codes were clearly different.

• Proceedings of the KIEE Conference
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• summer
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• pp.839-841
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• 2004

IEC 60044-6 (Requirements for protective current transformers for transient performance) was established to Korea Standard (KS C IEC 60044-6 ; Instrument transformers Part 6 ; Requirements for protective current transformers for transient performance) in December 11, 2003. In this paper, requirements, test items and test methods protective current transformers for transient performance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1722-1729
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• 1994

At early stage of creep-fatigue crack growth tests, initial transient behavior which implies high crack growth rate has been generally observed by some researchers. Since the influence of the initial transient crack growth behavior on the remaining life of components is significant, cause of it should be further studied. In this study, characteristics of the initial transient behavior of 1Cr-1Mo-0.25V steel is studied experimentally by performing creep-fatigue crack growth tests at $538^{\circ}C$ in air under trapezoidal waveshapes. It is verified that the cause of the initial transient behavior is not high ${(C_t)}_{avg}$ values due to the small scale creep condition at the early stage of test, but oxidation-dominated crack growth mechanism during the transient period which is different from the creep-dominated crack growth mechanism in steady crack growth period.

• Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.55-59
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• 2013

Before avionics equipment are installed in aircraft, several environmental tests such as temperature, vibration, lightning, fire etc. must be conducted. One of the environmental tests is to substantiate protection designs of lightning indirect effect. It can be showed through RTCA DO-160G, section22 "Lightning Induced Transient Susceptibility" test. An additional test of aircraft level is required as well after installation of avionics equipment.