• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.611-615
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• 2015

Anti-aircraft gun system is used for low-level air defense system and has more than twin guns with high firing rate in order to maximize the capability of defense. Gun's vibration and bullet's variance has a critical effect on accuracy and hit probability of weapon system such as anti-aircraft gun system with high firing rate. Typical mechanism to reduce the amount of vibration and shock during gun-fire process is very important design factor. In this paper, the suspension characteristics of the vehicle are studied for the improvement of isolating performance of gun firing system with high firing rate. Gun fire test for the vehicle is conducted and computational models using Recurdyn and Adams are created based on test results. Through this study, results of computational analysis are compared with the real test results, which includes type, location and quantity of suspension and gun mechanism are selected for anti-aircraft gun. From the result of this study, we could make basic design and consider the proper component of the system such as suspension and gun spring.

• Journal of the Korean Wood Science and Technology
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• v.46 no.5
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• pp.437-448
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• 2018

Physical characteristics of Korean red pine (Pinus densiflora) were investigated with different cultivation locations in Taebaek Mountains as Goseong-gun, Hongcheon-gun and Bonghwa-gun as experimental sites. Moisture content based on air-dried or green (artificial) wood was no significant differences with different cultivation places. Specific gravities of both sapwood and heartwood of red pine from Bonghwa-gun were higher than those from other two sites (Hongcheon-gun or Goseong-gun). Specific gravity of heartwood of red pine from Goseong-gun was higher than it from Hongcheon-gun, but this trend was opposite in case of sapwood. Higher specific gravity of red pine heartwood from Goseong-gun maybe resulted in higher strength than those of other sites. In shrinkage ratio, there was no significant difference among different cultivation places in radial directions, but red pine from Bonghwa-gun was higher than those of other sites in tangential directions. Hygroscopicity was no significant differences with different cultivation places. These results will be helpful information for efficient use of pinewood and good quality of pinewood production for genetical breeding improved.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.23-29
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• 2002

This paper is studied to investigate the effect of slits and swirl vanes on the main flow fields of a gun-type gas burner through X-Y plane and Y-Z plane respectively by using X-probe from hot-wire anemometer system. This experiment was carried out with flow rate $450{\ell}/min$ in respective burner models installed in the test section of a subsonic wind tunnel. The burner models with only slits and only swirl vanes respectively were made by modifying original gun-type gas burner. The fast jet flow spurted from slits played a role such as an air-curtain because it encircled rotational flow by swirl vanes and drives mixed main flow to axial direction. As a result, the gun-type gas burner had a wider flow range up to about Y/R=1.5 deviated from slits and maintains a comparatively large velocity in the central part of burner within the range of about X/R=2.5. Therefore, it was very desirable that swirl vanes were installed within slits in gun-type gas burner in order to control the main flow fields effectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.20-29
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• 2001

We recently developed a friability test procedure, which will be used as one of substance tests for Extremely Insensitive Detonating Substances(EIDSs) in Test Series 7 of the United Nations. This test was intended to assess the susceptibility of insensitive explosives to the break-up as high strain rate and subsequent ignition characteristics of the deformed material. We designed an air gun system using the hydro code simulation. The projectile velocities of the gun were in good agreement with those predicted by the hydro code with an inert material. Three different types of explosives, melt castable Comp B, castable plastic bonded explosives(PBXs), and pressable PBXs were tested during the development of the test procedure. Two tastable PBXs, i.e. DXD-09 and DXD-10, which are currently under development as candidate formulations of EIDS were classified as EIDS, since test results with these formulations were far better than the criterion of the UN Test Series 7.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.914-924
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• 2003

The interaction and breakdown of vortices over the Leading Edge Extension (LEX) - Delta wing configuration has been investigated through wing-surface pressure measurements, the off-surface flow visualization, and 5-hole probe measurements of the wing wake section. The description focused on analyzing the interaction and the breakdown of vortices depending on the angle of attack and the sideslip angle. The Effect of angle of attack and sideslip angle on the aerodynamic load characteristics of the model is also presented. The sideslip angle was found to be a very influential parameter of the vortex flow over the LEX-delta wing configuration. The introduction of LEX vortex stabilized the vortex flow, and delayed the vortex breakdown up to a higher angle of attack. The vortex interaction and breakdown was promoted on the windward side, whereas it was suppressed on the leeward side.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.34-40
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• 2016

A satellite is exposed to various impact environment until orbit entry. It is particularly undergoing the biggest impact by pyro shock, which is generated when the launch vehicle stages are separated or the satellite is separated from the launch vehicle. In this paper, due to the fact that the pyro shock is prerequisite for performing the test and verification on the ground, we developed an air-gun type shock tester for NEXTSat-1 shock test at the KAIST SaTReC along with the development of program introduced by LabVIEW software. The program operated in shock tester is consist of data measurement and analysis with the convenient implementation of user interface and its easy modification of the code.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.397-398
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• 2006

In late years, from a trend for ecology of auto motive engine, low emission and low fuel consumption of engine become a social assignment. At the same time, the high output (high efficiency) is required, too. In order to meet those requirements, in comparison with conventional engines, lean A/F (Air fuel ratio) setting is becoming popular for the high performance engines of late years. Exhaust valve seat (sintered material) used in these engines has a problem in wear resistance, because it is exposed to the surroundings that is clean and a high temperature in comparison with the conventional engines. Therefore, wear mechanism with lean A/F of engine was analyzed.The exhaust valve seat (sintered material), that was superior in wear resistance, was developed.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.122.1-122
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• 2001

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.102-105
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• 2001

Numerical simulations of coal combustion were carried out to identify what kind of burner design parameters are affecting the NOx emission. Where used burner design parameters are primary air velocity, secondary air velocity, $2^{nd}/3^{rd}$ air ratio, tertiary air velocity, and tertiary air injection location. Taguchi method was used to find the effective burner design parameters related to NOx formation. The results of numerical simulations showed that secondary air velocity and $2^{nd}/3^{rd}$ air ratio was the key parameters reducing the NOx emission. The total number of simulation cases was reduced by Taguchi method.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.6
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• pp.788-793
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• 2017

This military aircraft requires the compatibility evaluation of armed installations in accordance with guidelines and standards. In order to ensure the influence of gas-air mixtures caused by gunfire of the supersonic aircraft, CFD analysis of internal and external flows was performed and the results carried out and discussed. The low velocity vortex was formed due to the shape of the Gun Port, after firing the gas-air mixture was evacuated to the outside flow, where it moved to the front of the aircraft and soon merged with the aircraft flow field.