• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.74-80
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• 2014

This paper describes the development of the dual-thrust flight motor for enhancing the hit probability of unguided rockets. We designed dual-thrust flight motor by shape modification of the double base propellant with high burning rate, and confirmed the dual-thrust performance by static firing tests. The test results showed the thrust ratio of about 1:7.6 between sustaining phase and boosting phase, and had a quietly normal dual-thrust characteristics. And the results showed that there was not the fire extinction phenomenon of propellant due to the pressure drop.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.90-95
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• 2014

The system design and the system performance analysis of 3D imaging laser radar system for the mapping purpose is addressed in this article. For the mapping, a push-bloom scanning method is utilized. The pulsed fiber laser with high pulse energy and high pulse repetition rate is used for the light source of laser radar system. The high sensitive linear mode InGaAs avalanche photo-diode is used for the laser receiver module. The time-of-flight of laser pulse from the laser to the receiver is calculated by using high speed FPGA based signal processing board. To reduce the walk error of laser pulse regardless of the intensity differences between pulses, the time of flight is measured from peak to peak of laser pulses. To get 3D image with a single pixel detector, Risley scanner which stirs the laser beam in an ellipsoidal pattern is used. The system laser energy budget characteristics is modeled using LADAR equation, from which the system performances such as the pulse detection probability, false alarm and etc. are analyzed and predicted. The test results of the system performances are acquired and compared with the predicted system performance. According to test results, all the system requirements are satisfied. The 3D image which was acquired by using the laser radar system is also presented in this article.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.59-67
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• 2023

Recently, interest in flight simulators based on HMD and mixed reality is increasing. However, they have limitations in providing various interactions and a sense of presence to pilot wearing HMD. To overcome these limitations, a mixed reality image corresponding to the interaction under the actual cockpit environment must be generated in real time and provided to the pilot. For this purpose, we proposed a mixed reality image generation method, in which the cockpit area including the pilot's body could be extracted from real image obtained from the camera attached to the HMD and then composed with virtual image to generate a high-resolution mixed reality image. Simulation results showed that the proposed method could provide mixed reality images to HMD at 30 Hz frame rate with 99% image composition accuracy.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.100-108
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• 2013

In aerospace industry, MTBF (Mean Time Between Failure) and MFTBF (Mean Flight Time Between Failure) are generally used for reliability analysis. So far, especially to Korean military aircraft, MFTBF of avionic equipments is predicted by MIL-HDBK-217 and MIL-HDBK-338, however, the predicted MFTBF by military standard has a wide discrepancy to that of real-world operation, which leads to overstock and increase operation cost. This study analyzes operational data of avionic equipments. Operational MFTBF, which is calculated from operational data, is compared with predicted MFTBF calculated conventionally by military standard. In addition, failure rate trend is investigated to verify reliability growth in operational data, the investigation shows that failure rate curve from operational data has somewhat pattern with decreased failure rate and constant failure rate.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.116-122
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• 2016

The performance characteristics of a TBCC engine considering the transition mode from a turbojet to a ramjet engine has been investigated. The performance of each engine was proposed and a transition mode of the TBCC engine has been evaluated by adjusting the operating rate of the ramjet engine and turbojet engine performance changes continuously. Based on the transition model, it was confirmed that the performance is continuously changed at various flight Mach numbers and altitudes. The performance characteristics including thrust and specific impulse considering various flight conditions and transition mode were analyzed, which testifies characteristics of the engine itself, as well as transition of the combined cycle.

• Nuclear Engineering and Technology
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• v.11 no.2
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• pp.111-117
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• 1979

The light output of the NE213 liquid scintillator to electrons and protons was measured by coincidence spectrometer which employs the time of flight technique. The proton energies (3.2Mev, 4Mev, 5Mev, 6Mev) represent the kinetic energies of recoil protons from elastic scattering of a polyenergetic neutron source Am-Be (about 2-9 Mev) at angle of 45$^{\circ}$ and 60$^{\circ}$. The response of the NE213 liquid scintillator to protons was varied nonolinearly as the energy increased. while the response to electrons was varied linearly. The light intensity produced by electrons was relatively larger than that of protons in the rate of about three times when the same energy was introduced. The results of the light output to protons were similar to those of Batchelor et al.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.3
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• pp.277-284
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• 2013

In this paper, the ventilating and heating system of T-103 trainer aircraft were investigated and redesigned to improve its poor performance. The ventilation system of the trainer was designed to increase the mass flow rate of fresh air by using air intake valves. The flow-in air through the air intake valve is supplied to the cabin by the ram effect of aircraft and the propeller. And the additional heating system was installed to improve the temperature of the cabin inside. The wasted heat from the exhaust gas of the engines was used as heat source of the additional heating system by installing an heat exchanger around the exhaust nozzle. The additional fresh air and the heated air enter the cabin via two ducts mounted under the instrument panel and behind the pedal in the cabin. The additional ventilating and heating system can be controlled by the first pilot and the secondary pilot individually using the control knob equipped separately. After mounting the additional ventilating and heating system, evaluations such as inspection of parts and component, ground run-up test, in-flight test, user test, etc. were conducted. The result of the tests was sufficient to meet the requirements of the manuals, and the pilots were satisfied with the additionally mounted systems.

• Aerospace Engineering and Technology
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• v.11 no.2
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• pp.96-102
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• 2012

Recently, interests about frame error reduction method, using multiple PCM data which are received at several ground stations, are increasing. Simple data merge method is already applied to data processing system at Naro Space Center and have been used in the first and the second flight test analysis of KSLV-I. This paper is focused on error reduction with error correcting merge algorithm and time-delayed data correction algorithm. Result of applying the proposed algorithms to the flight test data shows 1.32% improvement in error rate, compared to simple-data-merge method. It is considered that presented algorithms could be very useful in generating various telemetry merge data.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2404-2412
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• 1994

A mathematical model has been developed for predicting kinematic, thermal, and solidification histories of atomized droplets during flight. Liquid droplet convective cooling, recalescence, equilibrium-state solidification, and solid-phase cooling were taken into account in the analysis of the solidification process. The spherical shell model was adopted where the heterogeneous nucleation is initiated from the whole surface of a droplet. The growth rate of the solid-liquid interface was determined from the theory of crystal growth kinetics with undercooling caused by the rapid solidification. The solid fraction after recalescence was obtained by using the integral method. The thermal responses of atomized droplets to gas velocity, particle size variation, and degree of undercooling were investigated through the parametric studies. It is possible to evaluate the solid fraction of the droplet according to flight distance and time in terms of a dimensionless parameter derived from the overall energy balance of the system. It is also found that the solid fraction at the end of recalescence is not dependent on the droplet size and nozzle exit velocity but on the degree of subcooling.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.981-992
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• 2006

In this paper, a lateral vehicle control using the concept of control configured vehicle (CCV) is presented. The control objectives for the lateral dynamics of a vehicle include the ability to follow a chosen variable without significant motion change in other specified variables. The analysis techniques for decoupling of the aircraft motions are utilized to develop vehicle lateral control with advanced mode. Vehicle lateral dynamic is determined to have the steering input and control torque input. The additional vehicle modes are also defined to using CCV concept. We use right eigenstructure assignment techniques and command generator tracker to design a control law for an lateral vehicle dynamics. The desired eigenvectors are chosen to achieve the desired decoupling (i.e., lateral direction speed and yaw rate). The command generator tracker is used to ensure steady-state tracking of the driver's command. Finally, the developed design is utilized by using the lateral vehicle dynamic with four wheel.