• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.6
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• pp.725-732
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• 2014

The silencer for the medium caliber gun was studied to reduce the propagation of gun-generated noise from the firing test range to the community. Three types of silencer were made to compare the reduction of sound pressure level and the effect of chamber volume and the exit angle to the reduction of sound pressure was considered. The structural analysis and measurement of pressure in the silencer showed that the structure is safe in terms of strength. The increase of recoil force to buffer must be considered in the development of silencer. The hypothesis test on the muzzle velocity for the existence of silencer showed that there are no difference at the significance level of 0.05.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.1023-1027
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• 1996

In this paper, the new technology and R&D status is presented, which accelerates the projectile using the electrical energy to overcome the limit of the conventional gun. The ETC (electro_thermal_chemical) gun, one kind of electric guns, seems to be the highly probable candidate as the next generation gun. The high density power supply and the forming and control of the current pulse are required to develop the ETC gun. And, the interior ballistics considered the mechanism of ETC gun must to be studied.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.204-212
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• 2014

The purpose of this paper is to investigate the effects of calibration rounds on the statistical distribution of the muzzle velocity in acceptance test of propelling charge. It is shown that the normal distribution fits best among statistical distributions from goodness-of fit test. The 3p-Weibull distribution is also acceptable because the shape of the probability density function curve is similar to that of normal distribution and it also has near zero skewness value. Muzzle velocities of test rounds uncompensated by calibration rounds showed high variation and had comparatively higher skewness. Because the skewness of normal distribution is defined to be zero, calibration rounds make the normality of data higher.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.279-282
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• 2011

Projectile can be damaged during the storage and handling. Maximum range calculation of the ammunition was performed on the assumption that each projectiles have 1.5mm/3.3mm axisymetric dent on the surface. Drag coefficient for trajectory calculation was delivered from CFD using commercial software FLUENT. In the result of CFD, damaged projectiles those have 1.5mm/3.3mm axisymetric dent have similar drag coefficient compare with normal projectile in the region of subsonic. But, in supersonic region, drag coefficient was increased 3%, 9% each in average. In the result of trajectory calculation, Maximum rage was decreased 1%, 3% each.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.88-94
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• 2006

In order to substitute current aluminum sabot and to increase the penetration performance of the kinetic energy projectiles, the research and development program for composites sabot has been conducted. For carbon/epoxy composites sabot, unidirectional carbon fiber reinforced epoxy prepreg was chosen and thick sectioned composites preforms with the different fiber angles along the circumferential direction of sabot were prepared by compression molding under the careful processing conditions at $150^{\circ}C$ for 1hour with $70kgf/cm^2$ curing pressure. The composites sabot demonstrated a weight reduction by approximately 30% than that of current aluminum sabot. The muzzle velocity of a kinetic energy projectile with composites sabot was measured to be about 63m/s higher than that with aluminum sabot. These results imply that the penetration performance is expected to be considerably increased when the composite sabot is applied to the kinetic energy projectiles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.47-50
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• 2003

JA2 Propellants, made by non-solvent process, are of great interest for the tank gun propellant. This is due to high energy. The grain geometries of JA2 and modified JA2 propellant were designed for application to 105mm APFSDS projectile. The combustion, thermochemical, and interior ballistic properties of the propellant were tested and calculated. The performances of the propellant were evaluated out using 105mm slug T2 projectiles and 105mm tank gun. The muzzle velocity of the propellants was higher than that of the KM30 for K274 projectile.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.615-621
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• 2011

In this paper, the proper quantity of conditioning rounds has been studied using the statistical analysis on the basis of the acceptance test data of K676 and K677 propelling charge for K9 self propelled howitzer. In general, the muzzle velocity of the initial rounds tends to be a little lower than that of the succeeding rounds. The latter rounds are likely to have the constant velocities after firing the appropriate conditioning rounds. The main cause of velocity difference was proved to be the proper quantity of conditioning rounds by doing the correlation analysis among the initial tube temperature, the tube life and the quantity of conditioning rounds. The result of paired t-test shows that two rounds of conditioning projectiles are proved to be enough to maintain the constant velocity in the case of the acceptance test of K676 and K677 propelling charge.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.4
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• pp.401-407
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• 2021

To confirm the change of muzzle velocity and the most suitable probability distribution model of the 155 mm K9 howitzer barrel with chrome plating and changed rifling. Using a statistical program, the muzzle velocity were plotted on a normal distribution, a 2-parameter and 3-parameter Weibull distribution on a probability paper. Also, statistical parameters were estimated and muzzle velocity fitness test and probability of K676 charge were plotted. In both the chrome-plated with standard rifling and changed rifling for K9 barrel, the 2-parameter and 3-parameter Weibull distribution were skewed to the left compared to the normal distribution. It was confirmed that the muzzle velocity of the K9 barrel with chromium-plated is suitable for the normal distribution and 3-parameter Weibull distribution model.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.618-624
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• 1989

Ultrasonically induced bubble formation in thermoplastic matrix was investigated experimentally and theoretically. polystyrene was saturated with nitrogen under the pressure of 0.2 to 3.45 MPa in a pressure chamber, followed by pressure release and ultrasonic bubble nucleation. Zinc stearate was added to polystyrene as the nucleating agent to induce heterogeneous nucleation. Various mixture of low density polyethylene and polyethylene wax was also saturated with the gas. The foamed specimens with or without ultrasonically induced bubble nucleation was modeled by modifying the classical nucleation theory. The rate of ultrasonic nucleation was predicted for homogeneous and heterogeneous nucleation at a conical cavity. This study showed that the heterogeneous and heterogeneous nucleation at a conical cavity. This study showed that the heterogeneous nucleation must be employed for ultrasonic production of bubbles in a viscous fluid and the homogeneous nucleation for ultrasonic production of bubbles in a low viscosity fluid.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.3
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• pp.27-35
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• 2013

This study intends to analyze the accessibility to the evacuation shelters according to pedestrian characteristics for Shinpo-district and Haewoon district, Masan Happo-gu, Changwon, designated as Disaster Risk Districts(Typhoon and Storm Surge Risk Zones) due to the typhoon and surge disasters of the past such as Typhoon RUSA or MAEMI. Evacuation speed was analyzed by dividing the types of evacuees into children, general adults, and the aged people by considering physical conditions. In the case of Haewoon district, currently designated evacuation shelters appeared to be appropriate. But in the case of Sinpo district, over 50% of designated Disaster Risk Districts appeared to be evacuation-vulnerable zones in the case of the aged. Therefore, three additional shelters were designated to complement these problems. The results reveal that the problems about the evacuation-vulnerable zones in the case of the existing designated shelters, appeared to be improved. It is expected that the results, obtained in this study will be utilized to establish the complementary measures to analyze the evacuation risk and solve the problems.