• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1903-1910
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• 2001

The BI(Ball Indentation) method has a potential to assess the mechanical properties and to replace conventional fracture tests. In this study, the BI test system has been developed to evaluate material properties. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed by the system using four classes of thermally aged specimens. The results of the BI tests were in good agreement with fracture characteristics from a standard fracture test method.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.78-84
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• 2009

This paper presents development results of integrated operating program and its simulator for an inshore test miner. The inshore test miner drives on the seabed and collects manganese nodules. For operating the test miner, integrated operating program (IOP) is needed for remote control and monitor of the miner in real-time. However, it is hard to develop the practical IOP for the test miner system, because the system is big, expensive, and unique. So a simulator was developed as a test substitute in order to save time and to reduce cost. Using test results of the simulator, the IOP of the test miner was developed. The developed IOP consists of remote program, host program, monitoring program and database program. The operating program was developed using PXI and Labview of NI. The experimental results are presented to show the applicability of the developed program.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.16-22
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• 2012

We performed impact test to estimate necessary explosive charge weight for cutting the cable whose diameter is 22 mm. The impact test results were analyzed by Probit method. The cutting energy was calculated 37.7 J with 99.99% probability at 99% reliability compared to the average energy of 24.9 J. The cable was cut 3 times without failure with 150 mg of Zirconium Potassium Perchlorate (ZPP), which was considered to generate 24.5 J of mechanical energy with assumption that only 10% of explosive energy converts to mechanical energy. The calculated energy from measured pressure with 150 mg ZPP was 26.1 J, which is almost same with both impact test result and expected mechanical energy. We can argue that the cable can be cut with 99.99% probability at 99% reliability by 230 mg of ZPP.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1026-1029
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• 2006

Particulate reinforced titanium composites were produced by PM rout. Differents volumetric percentages of TiN reinforcements were used, 5,10,15 vol%. Samples were uniaxial pressed and vacuum sintered at differents temperatures between $1200-1300^{\circ}C$. Density, porosity, shrinkage, mechanical properties and microstructure were studied. Elastic properties and strength resistance were analysed by flexural strength and tension tests, and after the test, fractured samples were analysed too, obtaining a correlation between the fracture, interparticulated or intraparticulated, and the reinforcement addition.. Hardness and microhardness test were applied too, in order to complete the study about mechanical properties. In order to study wear resistance pin-on-disc test were used. In addition, the temperature influence, the reactivity between matrix and reinforcement, and the microstructures developed were observed by optical and electron microscopy.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.286-291
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• 2003

In this paper, new measurement and analysis system for the durability test is introduced. Not like previous development cases, newly developed system can process both primary and secondary signals effectively to enhance the analysis performance. Developed system can be easily adopted to the industrial fields with little modifications. Compared to the commercial products, the system showed satisfactory performances.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.169-172
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• 2005

The performance test result of the Arm Fire Device(Ignition Safety Device) for solid rocket which prevents accidental ignition was described. The results of the closed bomb test and the igniter test of the classical mechanical arm fire device and the advanced electro-mechanical arm fire device were presented, and according to the igniter test result it was realized that the electro-mechanical arm fire device has an advantage in aspect of the action time.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.37-44
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• 2001

Ultrasonic testing has a characteristics such as excellent permeability, high-sensitivity to find defect and an almost exact measurement for position. size and direction of inner defect, which differ from other non-destructive testing. In the study, we developed program into optimal testing condition, to distinguish obstacle echo and defect position. This program shows generation and processing of ultrasonic pulse. We compared simulation with ultrasonic test in 45$^\circ$, 60$^\circ$and 70$^\circ$transducer. Test results were in accordance with simulation within 0.1~7.2%.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.3
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• pp.21-27
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• 2002

In this paper, a simple test rig of high-speed crash for the front members of vehicles was developed for the improvement of crashworthiness of vehicle's side rail. The cart hanging the specimen is accelerated up to 35 mph by the traction wire and by the force of freely dropping weight and 1:3 accelerating pulleys. The cart with shock absorbers travels on the rail roads, so it does not transfer any additional vibration to the specimen. In order to measure the energy absorbed by the specimen when it collapse to the wall and during it deform, the two strain gage type load cells are used at the wall place. The test rig rated good to test the specimen like a side rail of vehicle as developing the vehicle's structures in the early design stage.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.7-11
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• 2010

Difficulties associated with full-scale pipe tests are rather obvious. That is, it is not only difficult to perform them but also very expensive and it requires lots of experience. And the process of the fracture test for the pipe specimen is very difficult and complicated. Because the pipe specimen, the test jig and the test equipment are very large and heavy, it requires lots of costs and times. In this study, to easily perform the fracture toughness test for a pipe specimen, load line displacement data was obtained using the image processing method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.200-203
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• 2011

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.