• Journal of Power System Engineering
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• v.19 no.5
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• pp.60-66
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• 2015

Embrittlement of material by hydrogen charging should be cleared for safety of storage vessel of hydrogen and components deal with hydrogen. A stainless steel is generally used as materials for hydrogen transportation and storage, and it has a big advantage of corrosion resistance due to nickel component in material. In this study, microscopic damage behavior of stainless steel according to the hydrogen charging time using nondestructive evaluation was studied. The surface of stainless steel became more brittle as the hydrogen charging time increased. The parameters of nondestructive evaluation were also changed with the embrittlement of stainless steel surface by hydrogen charging. Ultrasonic test, which is the most generalized nondestructive technique, was applied to evaluate the relationship between the ultrasonic wave and mechanical properties of stainless steel by hydrogen charging. The attenuation coefficient of ultrasonic wave was increased with hydrogen charging time because of surface embrittlement of stainless steel. In addition, acoustic emission test was also used to study the dynamic behavior of stainless steel experienced hydrogen charging. AE event at the hydrogen charged specimen was obviously decreased at the plastic zone of stress-strain curves, while the number of event for the specimen of hydrogen free was dramatically generated when compared with the specimens underwent hydrogen charging.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.11
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• pp.898-905
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• 2018

In this work, infrared targets for a developed hardware-in-the-loop simulation(HILS) system are proposed for a performance test of a dual-sensor imaging seeker equipped with an infrared and a visible sensor that can lock and track for ground and air targets. This integrated system is composed of 100 modules of heat and light sources to simulate various kinds of target and the trajectory of moving targets based on scenarios. It is possible to simulate not only the position, velocity, and direction for these targets but also background clutter and jamming environments. The design and measurement results of an infrared target, such as the HILS system configuration, developed for testing and evaluation of a dual-sensor imaging seeker are described. In the future, it is planned to test the lock-on and tracking performance of an imaging seeker equipped with single or dual sensors dynamically in real time based on a simulation flight scenario in the developed HILS system.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.99-107
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• 1998

A test on venturi-type premixer of ASE120 engine combustor has been performed to evaluate its mixing performance. Cold air was supplied into the premixer through the fuel nozzle and mixed with the hot air from the compressor exit. The measured temperature of the mixed air was used to evaluate the mixedness. DOE(Design of Experiment) technique was utilized to make a test matrix of variables and to determine the optimum combination of variables, which was verified through a confirmation test.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.3
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• pp.205-210
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• 2017

Critical speed analysis was conducted for a active steering bogie prototype, developed to improve the curving performance of railway vehicles. The critical speed for the design concept was about 169.2k m/h. To validate the analysis result, we performed a critical speed test for the prototype bogie using a roller-rig tester. The test results showed that the critical speed for the prototype bogie was about 165 km/h. From the analysis and test results, The critical speed for the prototype bogie was determined to be 165 km/h. Considering the maximum operating speed of the test vehicle is 100 km/h, the prototype bogie is considered stable.

• The KSFM Journal of Fluid Machinery
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• v.16 no.2
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• pp.5-9
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• 2013

The aim of present study is to evaluate the stability of GM(Metacentric Height) calculation and investigate the damping effect of free rolling test. Moreover, GZ(Righting arm in stability) curve shows that it can provide reasonable design conditions for Fish boat. The roll damping characteristics of the improved model for an 7.9 ton class fishing boat are investigated through the free roll test in towing tank. The safety and boarding sensitivity are evaluated by GM calculation and roll motion period. Therefore, the results in this paper describe that the effect for improved hull is more improved than the original hull.

• Journal of KSNVE
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• v.10 no.2
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• pp.261-268
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• 2000

The instrumented capsule is subjected to flow-induced vibration(FIV) due to the flow of the primary coolant and then the structural integrity of the capsule during irradiation in the HANARO reactor is an issue of major concern. For this purpose the acceleration was measured by four accelerometers attached to the protection tube of the capsule mainbody and the displacement of test holes was calcultated using commercial finite element program ANSYS to evaluate the structural interference with the neighboring flow tubes under the reactor operating condition. The calculated displacements of test holes in the reactor in-core were found to be lower than the values of allowable design criteria.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.155-160
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• 2001

The road simulator system can simulate the longitudinal, lateral, and vertical movement changed by road conditions and vehicle dynamic characteristics while driving. This system provides the durability evaluation of vehicle suspensions. The system consists of hydraulic actuators, link mechanism, and servo controller. The hydraulic actuators are specially manufactured using low friction seals to endure high speed movement. The link mechanism is designed in order to minimize the dynamic effect during motion and remove the interference between 3axes actuators. The servo controller is composed of sensors, sensor amplifiers - displacement transducers and load cells, and an industrial PC with DSP board which calculates the control algorithm to control hydraulic actuators. The test results are included to evaluate the performance of this simulator comparing vehicle driving test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.330-333
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• 2000

Dimensional accuracy and surface quality are very important in rapid prototyping especially when the models are used for the production of tools. This paper presents the development of benchmarking part to investigate dimensional accuracy and surface finish. A new test part is designed to perform benchmarking of major rapid prototyping processes such as selective laser sintering, laminated object manufacturing, stereolithography apparatus, and fused deposition modeling. The test part design includes basic manufacturing features such as holes, walls, squares, cylinder and etc. In addition, the small features are included in order to evaluate the fine details that can be manufactured by a specific RP process. The CMM program that automatically measures different features in the test part is also developed. The evaluation of accuracy as well as surface roughness are discussed for major rapid prototyping processes.

• International Journal of Reliability and Applications
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• v.10 no.2
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• pp.109-118
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• 2009

Crankshaft, the core element of the engine of a vehicle, transforms the translational motion generated by combustion to rotational motion. Its failure will cause serious damage to the engine so its reliability verification must be performed. In this study, the S-N data of the bending and torsion fatigue limits of a crankshaft are derived. To evaluate the reliability of the crankshaft, reliability verification and analysis are performed. For the purpose of further evaluation, the bending and torsion tests of the original crankshaft are carried out, and failure mode analysis is made. The appropriate number of samples, the applied load, and the test time are computed. On the basis of the test results, Weibull analysis for the shape and scale parameters of the crankshaft is estimated. Likewise, the $B_{10}$ life under 50% of the confidence level and the MTTF are exactly calculated, and the groundwork for improving the reliability of the crankshaft is laid.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.3
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• pp.368-375
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• 2012

Durability performance evaluation of automotive components is very important and time consuming task. In this paper, to reduce vehicle component development time and cost virtual testing simulation technology is used to evaluate durability performance of a passenger car front aluminum sub-frame. Multibody dynamics based vehicle model and virtual test simulation model of a half car road simulator are validated by comparisons between rig test results and simulation results. Durability life prediction of the sub-frame is carried out using the model with road load data of proving ground which can evaluate accelerated durability life. We found that the durability performance of the sub-frame is sufficient and it can be predicted within short time compared to rig test time.