• Composites Research
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• v.23 no.6
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• pp.14-18
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• 2010

Among the factors that threaten spacecraft, Micrometeoroid and Orbital Space Debris(MMOD) cause damage to spacecraft and impact velocity is about 8~70km/s. Nowadays, various Whipple Shield are studied and applied to protect spacecraft. As the materials used to Shielding System, aluminum is usually used but composite is also used increasingly. So this study compared characteristics of hypervelocity impact of Aluminum and composites through finite element analysis. The Projectile was a spherical shape using Aluminum 2017-T4, and aluminum plate was using Aluminum 6061-T6, CFRP plate was using T300/5208. Initial impact velocity of projectile was 1km/s. As a result, kinematic energy of projectile decreased to about 64J and about 63J for aluminum plate and CFRP plate, respectively after impact. Although both results is almost same about the absorption of impact energy, you can think the CFRP has good ballistic characteristic, because CFRP is lighter about 1.7 times compared with density of aluminum.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.195-201
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• 2016

An experimental study has been found the air guide grooves for reducing drag. When a bullet is fired and move in the air, the drag is generated. The vortex which is one of the types of drag hinders the movement of the bullet. To solve this phenomenon, cut a negative grooves that we are called the air guiding grooves at the back of bullet. The grooves bullet has identified that the drag compared to conventional ammunition(KM80 and K193) is reduced to 4.480 and 4.054 : 10 % through a Finite Analysis Program($Ansys^{TM}$). Even pressure center was retreating 0.72 % compared to a Bullet(KM80 and K193). Effect obtained with these results is the accuracy of the grooves bullet in a shooting test was improved by over 32 %(KM80: 2.86, air guide grooves : 1.94) compared to conventional ammunition(KM80 and K193). In addition, muzzle velocity is increased 73 m/s. This is expected to be extended the velocity and effective range of bullet. Also, the velocity of the grooves bullet is increased when moving in the air while the velocity of the bullet(KM80 and K193) is reduced. The gas ejected from the muzzle to be balanced and stable flight of the Bullet. Given these effects, we can reckon the air guide grooves have positive influence.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.3
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• pp.20-28
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• 2015

Performance parameters of solid rocket motor with multi axis pintle nozzles were analyzed theoretically and modeled. For figuring out the governed variable of dynamic characteristics of system, dynamic analysis was done by using established model. To present characteristics of this system, the model should include not only internal ballistics of propulsion unit but also actuating system to move pintle. For solid rocket motor with multi axis pintle nozzles, not only performance of steady state but also dynamic characteristic of transient state is important design parameter to precise thrust control. Therefore, response time of open-loop system was analyzed by using established model and requirement about response time was satisfied by controlling pressure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.311-316
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• 2017

The network analysis method has emerged as a new methodology for various disciplines, due to its ability to provide a representative knowledge network of references, co-authors and keywords. Bulletproof technology is an interdisciplinary field involving various disciplines, such as material mechanics, structural mechanics, and ballistics, so it is essential to keep up with the recent trends in technological research. In this research, the recent R&D trends in the field of bulletproof materials were analyzed using keyword based network analysis. From the results, the core keywords were identified as 'Composite', 'Model' and 'Head' using the scholar search engine, google scholar. The centrality analysis for the core keywords showed that bulletproof technology has developed in 3 different areas, viz. material, structure and effects. To the best of our knowledge, this is the first application of (network analysis?) to bulletproof technology. Moreover, we are also convinced that the results of this study will be useful for defense technology planning and determining the direction of R&D in the field of bulletproof technology.

• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.54-62
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• 2017

China has invested for military satellite technology development to construct the space-based surveillance system from existing land-based and aerostat surveillance system since 1960s to react rapidly for deployment of marine force of United States and surrounding nations in west Pacific, south China sea and Indian ocean. China has also launched about 40 the Yaogan military intelligence satellites series for EO, SAR and ELINT fields since 2006 after the required technique with several technical experiment satellites launch and operational test. ELINT satellites transmit data from satellite to earth station in real time with construction space-based network around it. Those data are simultaneously delivered to Anti-Ship Ballistic Missile(ASBM) connected land-based C4ISR network for marine target attack. Therefore China has enhanced surveillance and attack capability to the surrounding marine nations with space-based network around it. In the future, It is considered that China will increase accurate location search, signal processing and analysis ability through a further study on its technology.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.7
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• pp.552-560
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• 2013

Airplane Buhwal is the first light airplane which is designed and made in South Korea. Restoration of airplane Buhwal is designed based on the one made by Korean Airforce in 2004 but there are some changes also. It uses aluminum main wing, electronic indicator, BRS(Ballistic recovery parachute) and black box for improved performance. In this paper, for the restorated Buhwal, major design changes are introduced, structure, aerodynamic and stability analysis are reviewed and improved performances which is proven through flight test are shown. This study will be a big help for domestic light airplane development.

• Strategy21
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• s.39
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• pp.47-81
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• 2016

This paper has attempted to examine the political and operational contexts within which North Korea's latest acts of nuclear blackmail, its test-firing of an SLBM on April 23rd 2016 and its fourth nuclear test on January 6^th 2016, should be understood. Analysis of the KN-11 SLBM and the Sinpo-class SSB is based on official South Korean, US and others sources, especially the ROK MND, as well as other resources from South Korea, US and others. Unfortunately, the results of this exploration are inconclusive: there is simply not enough evidence available at present to either confirm or refute the existence of a functional North Korean SLBM and SSB. Nevertheless, the North Korean determination to possess such assets should not be taken lightly. But even accepting North Korea's claims about its SLBMs at face value, which is undermined by news of apparently unsuccessful follow-up test-firings in November, and probably December 2015, there is little proof that North Korea has yet succeeded in miniaturizing its nuclear warhead, so the most extravagant fears are not yet justified. Taken together with North Korea's latest announcement of a supposed successful SLBM ejection-test, on March 23^th 2016, the KN-11 SLBM claims should probably be seen as primarily about proving North Korea's status as a nuclear power, both to exert external political pressure and to bolster internal political support for Kim Jong-un's rule. In conclusion, this paper recommends formulating a preemptive anti-access strategy for the ROKN, proposes acquiring an ASW CV and SSNs to implement submarine strategic deterrent patrols, and urges extending the existing limited AORs to facilitate the preemptive anti-access strategy. Other deterrence options may be suggested, but it is surely significant that the ROKN has recently publically referred to the deployment of an ASW CV and SSNs for the first time.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.68-75
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• 2015

In this paper, unsteady characteristics of pressure in solid rocket motor were analyzed by using response of pintle actuation, pressure and thrust data from ground test. Pressure and thrust in solid rocket motor can be controlled in real time by varying nozzle throat area with pintle, installed in the valve. Unsteady characteristics of pressure can be observed in this system occurred by various reasons. Two critical reasons, error of pintle actuation and ablation of center tube, are found and effects of each reason can be analyzed individually by re-prediction of pressure with response of pintle actuation and analyzing thrust to pressure ratio.

• Composites Research
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• v.28 no.4
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• pp.176-181
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• 2015

In this study, the Z-shape fabric design is proposed as the way to enhance the ballistic performance of fabrics which are used as the intermediate layer of stuffed Whipple shield configurations. The Z-shape fabric employs a different boundary condition from those of conventional configurations of fabrics which include 4 edge fixed. Impact analysis on Z-shape aramid yarns and fabrics using LS-DYNA software was performed and the results were compared with 2 edge fixed and 4 edge fixed fabrics to identify the high velocity impact energy absorption characteristics of the Z-shape fabric. It was revealed that the Z-shape showed different impact behavior and higher energy absorption performance than 2 and 4 edge fixed fabrics.

• Composites Research
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• v.32 no.2
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• pp.120-126
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• 2019

Advanced fiber fabrics have been utilized in not only anti-stabbing and bullet-proofing for body armor but also various industrial fields including vehicular armor and spacecraft structure. Furthermore, there have been a number of research to improve the ballistic performance of advanced fabrics introducing many computational approaches. In our research, an advanced fabric, Heracron manufactured in South Korea was modelled firstly using Autodyn, a commercial software specializing in impact and explosion phenomenon. The sensitivity of the input parameters was also confirmed by conducting simulations. To verify the numerical modelling, we measured and compared the simulation results with velocity decrements after impact involving one, three, and five layers of Heracron under 200-500 m/s impacts by an aluminum spherical projectile. The Heracron fabric was successfully modelled using Autodyn.