• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.657-665
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• 2016

Launch Control System(LCS) performs the pre-launch preparation and launch operation during launch campaign. The successful launch operation is basically influenced by hardware and software of LCS. Especially, a trivial errors in control algorithm can cause critical problem or disaster in launch operation. Therefore, the hidden or implicit errors should be distinguished and eliminated by the verification test in advance. In this paper, the design and implementation of hardware and software simulator which have already been used in LCS verification will be introduced. By presenting the detailed design and flowchart-based algorithms, we make other similar systems adopt the implementation philosophies of this paper. Especially, this paper emphasizes that all the simulation algorithms work on the self-controller in LCS without using separated computer or PLC.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.2
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• pp.115-123
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• 2018

In a long-span bridge, the cables are important elements that support the load of the bridge. Accordingly, the cable tension is a very important variable in evaluating the health and safety of the bridge. The most popular methods of estimating the cable tensions are the direct method, which directly measures the cable stresses using load cells, hydraulic jacking devices, etc., and the vibration method, which inverses the tensions using the cable shapes and the measured dynamic characteristics. Studies on the use of the electromagnetic (EM) sensor, which detects the magnetic field variations caused by the change in the stress of the steel in the cable, are increasing. In this study, the lift-off test, the EM sensor, and the vibration method (Vision-based System and Accelerometer) were used to measure cable tension, and their results were compared and analyzed.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.80-88
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• 2018

The function of a vehicle holding device (VHD) is to securely hold a launch vehicle on the launch pad and release the launch vehicle at maximum thrust after engine ignition to allow lift-off of the launch vehicle. During the release of the launch vehicle, to prevent the Ka doing a doing a doing mode, which is the vertical oscillation of the entire liquid propellant, the release of the launch vehicle should be gradual. In this study, for the gradual release of a launch vehicle, a hydraulic system comprising an accumulator and pyro valve to operate a hydraulic cylinder and control the speed of the cylinder with an orifice is introduced. Through a test, the influence of design variables on the cylinder speed is analyzed. Based on this, the design values of the hydraulic cylinder are determined. Through this study, the engineering basis for developing a VHD releasing a launch vehicle at maximum thrust is provided.

• Applied Microscopy
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• v.38 no.4
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• pp.339-345
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• 2008

In this study, we compared the stress and tensile strength of the hair treated with oxidative permanent dye with those of virgin hair. We investigated the fine structure of the hair section after the tensile test using scanning electron microscopy. The tensile strength of the virgin hair was measured as $14.66\;g/cm^2$, tensile energy was $108\;erg/cm^2$, and the maximum stress was 146.64g. Those of the dyed hair were $13.69\;g/cm^2$, $89.62\;erg/cm^2$ and 136.90 g, respectively. The differences in the tensile strength, the tensile energy and the maximum stress were $-0.97\;g/cm^2$, $-18.38\;erg/cm^2$, -9.74 g, respectively, which showed that the dyed hair had less elasticity and strength than the virgin hair. In the scanning electron microscopy investigation of the damaged hair after the tensile test, lift-off of the cuticle outer layer were shown in both virgin hair and dyed hair, which was more severe in the dyed hair than the virgin hair. Adjacent cuticular cells of the cuticle layer were separated by the destruction of intercellular membrane complex. The macrofibrils were exposed and separated from the cortex torn by tensile strength.