• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.1
• /
• pp.79-85
• /
• 2008

Generally Solid Rocket Motor(SRM) has advantages like this - safety, simplicity and flexibility in design and manufacturing process. However, once propellant grain shape and nozzle throat area are determined, modification of thrust magnitude is nearly impossible. Recently, methods for controlling the thrust magnitude of SRM are vigorously developed. This paper predicts internal ballistic performance variation, especially thrust of SRM by means of Linear Approximation according as chamber pressure or nozzle throat area is changed. The results predicted by the proposed method are good agreement with the those of exclusive Ballistic Performance Prediction Program(SPP).

• Journal of the Korea Institute of Military Science and Technology
• /
• v.19 no.1
• /
• pp.95-104
• /
• 2016

To make a firing table of artillery with trajectory simulation, a precise trajectory model which corresponds with real firing test is required. Recent 4-DOF modified point mass trajectory model is considered accurate as a theoretical model, but fitting coefficients are used in calculation to match with real firing test results. In this paper, modified point mass trajectory model is presented and method of setting ballistic coefficient is introduced by applying optimization algorithms. After comparing two different algorithms, Particle Swarm Optimization and Covariance Matrix Adaptation - Evolutionary Strategy, we found that using CMA-ES algorithm gives fine optimization result. This fitting coefficient setting method can be used to make trajectory simulation which is required for development of new projectiles in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.47 no.3
• /
• pp.228-239
• /
• 2019

In order to design the conceptual configuration of the short-range ballistic missile, the authors have established an optimization problem considering various aspects such as volume, aerodynamics, propulsion, structure, stability, and flight trajectory. For this purpose, the existing missile cases were analyzed and the design conditions and performance indices were derived. The performance of the whole system was analyzed by integrating each subsystem's model. Through the design example, we analyzed the relationship between various design variables and final performances.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.8
• /
• pp.531-540
• /
• 2022

In this paper, we present an algorithm that identifies artillery type and rapidly predicts the impact point based on the IMM filter. The ballistic trajectory equation is used as a system model, and three models with different ballistic coefficient values are used. Acceleration was divided into three components of gravity, air resistance, and lift. And lift acceleration was added as a new state variable. The kinematic condition that the velocity vector and lift acceleration are perpendicular was used as a pseudo-measurement value. The impact point was predicted based on the state variable estimated through the IMM filter and the ballistic coefficient of the model with the highest mode probability. Instead of the commonly used Runge-Kutta numerical integration for impact point prediction, a semi-analytic method was used to predict impact point with a small amount of calculation. Finally, a state variable initialization method using the least-square method was proposed. An integrated algorithm including artillery type identification, impact point prediction and initialization was presented, and the validity of the proposed method was verified through simulation.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.2 no.2
• /
• pp.47-51
• /
• 1978

In order to improve the hitting rate in the shot of rifles, it is required that the analysis of exterior ballistics and the line of sight. One of the important factors influenced a marksman using a rifle obtained the zero-setting of a rifle at the horizontal range, is the deviation of the impact point from the aiming point when the shooting is performed in an inclined ranges. The deviation usually cccurs from the reaction force along the bore line, the characteristics of exterior ballistics, and the error of a shooting range judgement by the inclined range. This study is concerned with the problem of the vertical difference between the impact and aiming point in the inclined shooting ranges. The computing method to find the vertical difference is represented. This method is applied for and experimental rifle in three cases, (1) hofizontal shooting ranges, (2) upper inclined shooting ranges, and (3) lower inclined shooting ranges.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.10 no.2
• /
• pp.31-37
• /
• 2007

This paper presents a ballistic lead-computation method which utilizes automatic video tracking, tracking assistance and roll uncoupling. The method is able to improve the firing accuracy of army fighting vehicles such as main battle tanks. In the experiment, the efficiency of the proposed method is evaluated by an error analysis in real operating environment. The proposed method has been applied to the fire control system of a military vehicle and proved through the development test of the vehicle.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.3
• /
• pp.349-357
• /
• 2010

In this paper, a numerical code for the interior ballistics has been investigated. The Eulerian-Lagrangian approach and the SMART scheme have been used in the numerical code for the grain combustion. The translational kinetic energy of the projectile and work done against barrel friction have been considered only. The ghost cell extrapolation method has been used for the chamber change with the projectile movement. The calculation results of the numerical code have been compared and verified through those of IBHVG2 code.

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.5
• /
• pp.589-600
• /
• 2022

In order to verify the reliability of Dry Test Bench (DTB) used for testing the output energy from ballistic extracorporeal shock wave therapeutic devices, the measurements with DTB were compared with the acoustic energy measured with a Laser Doppler Vibrometer (LDV) for a commercial ballistic ESWT device. It was shown that the mechanical energy detected with DTB had variability maintained within 5 % at the same output power setting and also had a linear correlation (adj. R² = 0.991) with the acoustic energy measured with the LDV for the entire output power settings. Using the correlation between the two methods and the correlation on the acoustic energy measured in between air and water with the LDV, the DTB measurement can be used to estimate the energy flux density in water with an average error of 7.85 % for the entire output power settings of the ballistic shock wave generator considered in the experiment. DTB provides information limited to the output mechanical energy and therefore it is not suitable for testing the various acoustic output parameters required in IEC61846 and IEC63045. However, DTB that is simple in measurement principles and easy to use is expected for manufacturers and clinical users to monitor the performance of ballistic Extracorporeal Shock Wave Therapy (ESWT) devices.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.9 no.2
• /
• pp.1-8
• /
• 1991

The geoid is the one of major suject in Geophysics and Geodesy. The iregularities of the geoid will affect the computation of precise geodetic coordinates and moreover will cause an errors in trajectory computations and reference directions for inertial guidance system. The aim of this study is to develope the best local geoid model for Korea. For this purpose, an astrogeodetic levelling and surface fitting techniques have been applied in determination of the geoid as a first trials. As a result of it, a local geoid has been obtained with the standard errors of $\pm$0.49m and $\pm$0.66m respectively and the maximum geoid undulation in Korea is found as 22m~23m approximately.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.5
• /
• pp.405-412
• /
• 2015

This paper represents a filter design to estimate the airspeed of a spin-stabilized, trajectory-correctible artillery ammunition. Due to the limited power and space in operational point of view, the airspeed sensor is not installed, and thus the airspeed need to be estimated using limited sensor measurements. The only IMU measurements(three-axis specific forces and angular rates) are used in this application. The extended Kalman filter algorithm is applied since a linear filter can not cover the its wide operational range in airspeed and altitude. In the implementation of the EKF, the state and measurement equations are transformed into the no-roll frame for simple form of Jacobian matrix. The simulation study is conducted to evaluate the performance of the filter under various environment conditions of sensor noise and wind turbulence. In addition, the effect of the choice in filter design parameters, i.e. process error covariance matrices is analyzed on the performance of the estimation of airspeed and angular rates.