• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.311-318
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• 2018

In this paper, test-bed for the evaluation of wireless communication system on a small launch vehicle is proposed. The proposed test-bed consists of antenna test-coupler, RF attenuators, and RF switch modules. The antenna test-coupler isolates antennas for each band and transmits / receives wireless signals. The RF attenuator and switch are used for path selection of testing signal path. In design and measurement result of the antenna test-coupler, the antenna test-coupler has shielding effect higher than 39.3, 47.1, 56.1 dB at UHF-, S-, X-band. Through testing on small launch vehicle wireless communication system, we were able to successfully transmit and receive data between each test system and launch vehicle with antenna path switching.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.339-344
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• 2019

In order to prepare for the rise of data security threats caused by the information and communication technology, technology that can guarantee the stability of the data stored in the missile test set is important. For this purpose, encryption should be performed when data is stored so that it cannot be restored even if data is leaked, and integrity should be ensured even after decrypting the data. In this paper, we apply AES algorithm, which is a symmetric key cryptography system, to the missile test set, and Encrypt and decrypt according to the amount of data for each bit of each AES algorithm. We implemented the AES Rijndael algorithm in the existing inspection system to analyze the effect of encryption and apply the proposed encryption algorithm to the existing system. confirmation of suitability. analysis of capacity and Algorithm bits it is confirmed that the proposed algorithm will not affect the system operation and the optimal algorithm is derived. compared with the initial data, we can confirm that the algorithm can guarantee data undulation.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.38-51
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• 2018

This study was carried out to improve the performance characteristics of nozzleless boosters that are used in ramjet boosters. A propellant using Zr as the metal fuel was developed, which provided a higher density than the propellant using Al as the metal fuel. The developed propellant was cast using the nozzleless booster and a ground test was carried out by varying the length-to-diameter ratio (L/D ratio) of the propellant. From a comparison between the performance characteristics of propellants using Zr and Al, it was proved that the performance of the propellant using Zr is higher than that of propellant using Al, except for the specific impulse, under all tested conditions. As the length-to-diameter ratio was increased, the specific impulse of the propellant using Zr was decreased by 88% compared with that of the propellant with Al. However, because of the density difference between the propellants, the impulse density of the propellant with Zr was higher than that of the propellant with Al under all tested conditions.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.1
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• pp.8-16
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• 2017

Structural integrity of solid rocket depends on the residual reactions between constituents of its composition(post cure, migration etc.), the oxygen(or anti-oxydent) in the free volume and humidity (desiccant) under the perfect sealed condition. Mechanical Properties of composite solid propellant arising from those factors are very complex. Moreover the propulsion are faced with thermal loads from diurnal & seasonal cycle till firing. In this study, the fast evaluation method of long term mechanical properties is suggested based on Thermo-Rheological Simplicity from curing oven to cool-down stage in view point of thermal stabilization. For this subject, endurance tester having temperature control capability are devised. From the results from incremental load and strain, non-linear characteristics are discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.7-15
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• 2018

In this study, AOT that is used as a surfactant in various industries was applied to an HTPB/AP solid propellant. AOT is one of the anionic surfactants, and there have been cases where AOT was reported to induce self-extinguishable properties in propellants overseas. In this study, solid propellants using AOT were prepared, and their properties and combustion characteristics were investigated. The combustion rate of the AOT-applied propellant drops sharply when the pressure reaches a certain value during combustion. Further, the density and hardness of the propellant are lower than those of conventional HTPB/AP propellants.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.508-516
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• 2019

In this paper, we propose a guidance law to control Impact Angle in consideration of look angle limit of the missile with strapdown seeker on the non-maneuvering target. The proposed law is based on sliding mode algorithm and generates acceleration commands using look angle and line of sight information provided by the strapdown seeker and navigation system. And, target velocity and target path angle are provided by like TADS (Target Acquisition and Designation System) at launch time. We can confirm that the target interception and impact angle control are possible through the convergence of the proposed sliding surface. In addition, it is possible to confirm that the sign of derivative result of the look angle at the maximum and minimum look angle is opposite to the sign of the look angle, so the look angle limit is not exceeded.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.22-31
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• 2018

In this study, numerical simulations were performed to determine the dynamic characteristics of a pintle nozzle, with changes to the chamber boundary conditions. To apply movement, to the pintle, the nozzle and pintle were created separately by an auto-grid generation program using an overset grid method. The chamber boundary conditions were selected between a constant mass-flow rate condition and a propellant burn-back condition. The pressure and thrust characteristics of the constant mass-flow rate condition were determined by changing the ratio of the mass-flow rate in the inlet. The propellant burn-back condition was considered by formulation of the combustion rate. The burn-back conditions represented nonlinear phenomena, unlike the constant mass flow rate, and a small flow rate resulted in a large change in the chamber pressure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.245-255
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• 2019

This paper describes on aerodynamic analysis based on the truncation rate of guided-weapon nose using computational fluid dynamics. The shape to perform the analysis is only the body of the guided weapon and the diameter to length ratio is 10.7. Three nose shapes were selected and hemisphere, 25% and 50% truncation were compared. For the accurate CFD analysis of the body, the grid method and the analytical method were selected and verified using NASA wind tunnel test data. For the three nose shapes, the drag analysis for the flight Mach number is 6~20% different. This difference was analyzed by the pressure distribution from nose to base.

• Journal of the Korea Society of Computer and Information
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• v.26 no.6
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• pp.1-8
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• 2021

In this paper, we propose reinforced VGG style network structure for low performance embedded system to classify low resolution infrared image. The combination of reinforced VGG style network structure and global average pooling makes lower computational complexity and higher accuracy. The proposed method classify the synthesize image which have 9 class 3,723,328ea images made from OKTAL-SE tool. The reinforced VGG style network structure composed of 4 filters on input and 16 filters on output from max pooling layer shows about 34% lower computational complexity and about 2.4% higher accuracy then the first parameter minimized network structure made for embedded system composed of 8 filters on input and 8 filters on output from max pooling layer. Finally we get 96.1% accuracy model. Additionally we confirmed the about 31% lower inference lead time in ported C code.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.105-110
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• 2018

The North Korea nuclear issue is now posing a serious security threat to the Korea and Northeast Asia. Accordingly, the South Korean military is pushing for the introduction of long-range air-to-surface flights and the development of domestic nuclear facilities that can precisely hit North Korea headquarters building and nuclear facility even hundreds of kilometers above the border. In this paper, we removed the cable braid for securing the weight of the missile among several design elements for long-range air-to-surface missile development and estimated and analyzed the resulting performance. The possibility of braid removal was analyzed in terms of crosstalk inside the cable and CS114, RE101 of MIL-STD-461F.