• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.5
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• pp.712-719
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• 2012

Penetrator with enhanced lateral effect(PELE) is a newconcept projectile, without dynamite and fuze. It consists of high-density jacket, closed at its rear end and filled with a low-density filling material. To study the explosion characteristics of PELE, by AUTODYN-3D code, the calculation models of projectile body and bullet target are established and the process of penetrating aluminum-2024 alloy target of PELE is simulated, and the scattering characteristics after penetrating aluminum-2024 alloy target of PELE are studied by different initial velocity. The explicit finite element analysis of PELE fragmentation was implemented with stochastic failure criterion in AUTODYN-3D code. As expansion of filling, the fragments were obtained velocities and dispersed laterally and further more enhancing the damage area largely. The number and shape of the PELE fragments were different depend on impact velocity and incidence angle of filling which fragment generated during penetration and lateral dispersion process.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1139-1146
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• 2010

Simulated target generators are used to evaluate the various radar performance. Using the radar parameters such as target range(time delay), doppler frequency, target RCS, simulated target generator can be developed. Especially moving targets are simulated by control time delay and update target signal intensive for target range. Base on this concepts, in this paper, simulated target generators are designed and developed for X-band Radar performance test. Developed equipment is evaluated its performance and then tested with X-band Radar. This paper presents these design, development, and test results of developed target generator.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.2
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• pp.132-138
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• 1997

Six different types of velocity profiles of trolley movement of a container crane are investigated for the minimal sway angle at the target trolley position. Three velocity patterns which include trapezoidal, stepped and notched-type velocity patterns are obtained assuming constant rope length. The notched type velocity pattern is shown to be derived from the time-optimal bang-bang control. The stepped type velocity pattern can be shown to be derived as bang-off bang control as well. Considering the damping effect due to hoist motion a double stage acceleration pattern is also analyzed. The main objective of the paper is to show how much time-reduction can be obtained among several velocity patterns appearing in the literature.

• Journal of Biomedical Engineering Research
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• v.4 no.1
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• pp.15-20
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• 1983

In this paper, the velocity characteristics of the vertical saccadic eye movement system with subject-experiment are investigated utilizing the infra-red methed. Especially, target-generation system which produces pseudo-random signals using EPROM 2716 and differentiator whose time constant is 12 msec are developed in hardware.

• Physical Therapy Korea
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• v.15 no.3
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• pp.44-52
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• 2008

The purpose of this study was to investigate the effects of different objects and target location of dominant hand on the non-dominant hand movement kinematics in a bimanual reaching task. Fifteen right-handed volunteers were asked to reach from same starting point to the different target point of right and left hand with grasping the objects of different size. Independent variables were 1) three different object types (small mug cup, name pen, and PET bottle), and 2) three different target locations (shorter distance, same distance, and longer distance than the non-dominant hand) of the dominant hand. Dependent variables were movement time (MT), movement distance (MD), movement mean velocity ($MV_{mean}$), and movement peak velocity ($MV_{peak}$) of the non-dominant hand. Repeated measures two-way analysis of variance (ANOVA) was used to test for differences in the non-dominant hand movement kinematics during bimanual reaching. The results of this study were as follows: 1) MT of the non-dominant hand was increased significantly when traveling with grasping the mug cup and reaching the far target location, and was decreased significantly when traveling with grasping the PET bottle and reaching the near target location of the dominant hand. 2) MD of the non-dominant hand was significantly increased during reaching the far target location, and significantly decreased during reaching the near target location with dominant hand. 3) $MV_{mean}$ of the non-dominant hand was increased significantly when traveling with grasping the PET bottle, and was decreased significantly when traveling with grasping the mug cup of the dominant hand. Therefore, it can be concluded that the changes of the ipsilateral hand movement have influence on coupling of the contralateral hand movement in bimanual reaching.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.2 s.21
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• pp.49-57
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• 2005

The target localization using the line arrays buried in the seabed is a difficult problem due to the complex sea bottom characteristics and need to compensate the wave propagation effect to localize the target accurately Sound speed mismatch in the seabed causes a bias in the target bearing estimation and induces the localization error. In this paper we describe a target localization method with improved accuracy of target bearing and localization by calibration the sound speed in the seabed. The proposed algorithm is verified through the ocean data.

• The Journal of the Acoustical Society of Korea
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• v.42 no.1
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• pp.25-31
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• 2023

In order to estimate the radial speed of an underwater object so-called target with active sonar, Continuous Wave (CW) pulse is generally used, but if a target is slow and at near distance, it is not easy to estimate the radial velocity of the target due to acoustic reverberation in the ocean. In 2017, Wang et al. utilized broadband signal of two Hyperbolic Frequency Modulation (HFM) pulses, which is known as a doppler-invariant pulse, with equal frequency band and in opposite sweep directions to overcome this problem and successfully estimate the radial speed of slow-moving nearby target. They demonstrated the estimation of the radial velocity with computer simulation using the parameters of two HFM starting time differences and receiving times. However, for it uses two HFM pulses with equal frequency, cross-correlation between the two pulses negatively affect the detection performance. To mitigate this cross-correlation effect, we suggest using two different band HFM with the opposite sweep directions. In this paper, a method of radial velocity estimation is derived and simulated using two HFM pulses with the pulse length of 1 second and bandwidth of 400 Hz. Applying the suggested method, the radial velocity was estimated with approximately 6 % of relative error in the simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.7
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• pp.562-569
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• 2016

This paper proposes a navigation system with a robust localization method for an underwater unmanned vehicle. For robust localization with IMU (Inertial Measurement Unit), a DVL (Doppler Velocity Log), and depth sensors, the EKF (Extended Kalman Filter) has been utilized to fuse multiple nonlinear data. Note that the GPS (Global Positioning System), which can obtain the absolute coordinates of the vehicle, cannot be used in the water. Additionally, the DVL has been used for measuring the relative velocity of the underwater vehicle. The DVL sensor measures the velocity of an object by using Doppler effects, which cause sound frequency changes from the relative velocity between a sound source and an observer. When the vehicle is moving, the motion trajectory to a target position can be recorded by the sensors attached to the vehicle. The performance of the proposed navigation system has been verified through real experiments in which an underwater unmanned vehicle reached a target position by using an IMU as a primary sensor and a DVL as the secondary sensor.

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.830-835
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• 1998

The characteristics of the ablation plume generated by 532 nm Nd: YAG laser irradiation of a Pb(Zr0.52Ti0.48)O3 (PZT) target have been investigated using a pulsed-field time-of-flight mass spectrometer (TOFMS). The relative abundance of O+, Ti+, Zr+, Pb+, TiO+, and ZrO+ ions has been measured and discussed. TiO+ and ZrO+ ions were also found to be particularly stable within the laser ablation plasma with respect to PbO+ species. The behavior of the temporal distributions of each ionic species was studied as a function of the delay time between the laser shot and the ion extraction pulse. The most probable velocity of each ablated ion is estimated to be Vmp=1.1-1.6x 105 cm/s at a laser fluence of 1.2 J/cm2, which is typically employed for the thin film deposition of PZT. The TOF distribution of Ti+ and Zr+ ions shows a trimodal distribution with one fast and two slow velocity components. The fast velocity component (6.8x 10' cm/s) appears to consist of directly ablated species via nonthermal process. The second component, originated from the thermal evaporation process, has a characteristic velocity of 1.4-1.6 x 105 cm/s. The slowest component (1.2 x 105 cm/s) is composed of a dissociation product formed from the corresponding oxide ion.

• Journal of The Korean Astronomical Society
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• v.54 no.2
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• pp.71-88
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• 2021

We use N-body/hydrodynamic simulations to study the evolution of the spin of a Milky Way-like galaxy through interactions. We perform a controlled experiment of co-planar galaxy-galaxy encounters and study the evolution of disk spins of interacting galaxies. Specifically, we consider cases where the late-type target galaxy encounters an equally massive companion galaxy, which has either a late or an early-type morphology, with a closest approach distance of about 50 kpc, in prograde or retrograde sense. By examining the time change of the circular velocity of the disk material of the target galaxy from each case, we find that the target galaxy tends to lose the spin through prograde collisions but hardly through retrograde collisions, regardless of the companion galaxy type. The decrease of the spin results mainly from the deflection of the orbit of the disk material by tidal disruption. Although there is some disk material which gains the circular velocity through hydrodynamic as well as gravitational interactions or by transferring material from the companion galaxy, it turns out that the amount of the material is generally insufficient to increase the overall galactic spin under the conditions we set. We find that the spin angular momentum of the target galaxy disk decreases by 15-20% after a prograde collision. We conclude that the accumulated effects of galaxy-galaxy interactions will play an important role in determining the total angular momentum of late-type galaxies.