• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.3
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• pp.136-143
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• 2001

A micro particle manipulator, which is devised for trapping particles at fixed positions by negative dielectrophoretic force (DEP force), has been fabricated and experimented. It is composed of square type electrode arrays fabricated by nickel electroplating with the height of 28 ${\mu}m$. To improve the quality of electroplated nickel electrodes, plating conditions have been optimized. Micro particles used in this study are polystyrene spheres and their to the specific position and trapped. The DEP force along the moving path of the particles has been estimated by the motion equation of a single particle. The displacement of a particle with an elapsed time was measured using a high-speed camera (1000 frames/sec). The velocity and acceleration of the particle were calculated from the measured data. The DEP force acting on the particle was estimated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.566-569
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• 2008

Recently, the biolistic process is emerging as an effective needle-free drug delivery technique to transfer adequate concentrations of pharmacologic agents to soft living tissues with minimum side effects. We have started developing an effective method for delivering drug coated particles using laser ablation. A thin metal foil with deposited micro-particles on one side is irradiated with laser beam on the opposite side so that a shock wave is generated. This shock wave travels through the foil and is reflected, which causes and instantaneous deformation of the foil. Due to such a sudden deformation, the micro-particles are ejected at a very high speed. Here we present the experimental results of direct and confined laser ablation, which correspond to the initial stage of the whole experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.587-593
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• 2008

Transdermal and topical drug delivery with minimal tissue damage has been an area of vigorous research for years. Our research team has initiated the development of an effective method for delivering drug particles across the skin (transdermal) for systemic circulation, and to localized (topical) areas. The device consists of a laser ablation based micro-particle acceleration system that can be integrated with endoscopic surgical techniques. We have successfully delivered 3μm size cobalt particles into gelatin models that represent soft tissue with remarkable penetration depth.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.48-52
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• 2009

Micro-hole targets are studied to generate energetic protons from laser-thin foil targets by using 2-dimensional particle-in-cell simulations. By using a small hole, the maximum energy of the accelerated proton is increased to 4 times higher than that from a simple planar target. The main proton acceleration mechanism of the hole-targets is the electrostatic field created between the fast electrons accelerated by the laser pulse ponderomotive force combined with the vacuum heating and the target rear surface. But in this case, the proton angular distribution shows double-peak shape, which means poor collimation and low current density. By using a small cone-shaped hole, the maximum proton energy is increased 3 times higher than that from a simple planar target. Furthermore, the angular distribution of the accelerated protons shows good collimation.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.68-71
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• 2008

Transdermal and topical drug delivery with minimal tissue damage has been an area of vigorous research for a number of years. Our research team has initiated the development of an effective method for delivering drug particles across the skin (transdermal) for systemic circulation, and to localized (topical) areas. The device consists of a micro particle acceleration system based on laser ablation that can be integrated with endoscopic surgical techniques. A layer of micro particles is deposited on the surface of a thin metal foil. The rear side of the foil is irradiated with a laser beam, which generates a shockwave that travels through the foil. When the shockwave reaches the end of the foil, it is reflected as an expansion wave and causes instantaneous deformation of the foil in the opposite direction. Due to this sudden deformation, the microparticles are ejected from the foil at very high speeds, and therefore have sufficient momentum to penetrate soft body tissues. We have demonstrated this by successfully delivering cobalt particles $3\;{\mu}m$ in diameter into gelatin models that represent soft tissue with remarkable penetration depth.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.837-841
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• 2008

Propulsion of gene coated micro-particles is desired for non-intrusive drug delivery inside biological tissue. This has been achieved by the development of a device that uses high power laser pulses. The present paper looks at the mechanisms of micro-particle acceleration. Initially, a high power laser pulse is focused onto the front side of a thin aluminium foil leading to its ablation. The ablation front drives a compression wave inside the foil, thus leading to the formation of a shock wave, which will later reflect from the rear side of the foil, due to acoustic impedance mismatch. The reflected wave will induce an opposite motion of the foil, characterized by a very high speed, of the order of several millimeters per microsecond. Micro-particles, which are deposited on the rear side of the foil, thus get accelerated and ejected as micro-projectiles and are able to penetrate several hundreds of micrometers inside tissue-like material. These processes have been observed experimentally by using high-speed shadowgraphy and considered analytically.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.1
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• pp.37-42
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• 2020

This study is for a bulletproof experiment through speed acceleration of steel ball(2.385 mm) at the laboratory level. The secondary propulsion method is used for speed acceleration, which uses a sabot assembly consisting of a sabot body, a plunger, water, and a sabot cap. At the core of the secondary drive, it is important that the energy in the water of the private particle is transferred well to the steel ball. The experiment was conducted by selecting a plunger that pushes water and water charged with variables. judging that the longer the contact time, the greater the energy transferred to the steel ball. As a result of experiments with each variable, the amount of water does not affect the speed acceleration efficiency of the steel ball and, when the length of the plunger is increased by 200 %, the speed of the steel ball can be accelerated up to 130 m/s.

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.22-27
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• 2009

Target design study to improve the quality of an accelerated proton beam from the interaction of a high-intensity short pulse laser with an overdense plasma slab has been accomplished by using a two-dimensional, fully electromagnetic and relativistic particle-in-cell (PIC) simulation. The target consists of a thin core part and a thick peripheral part of equivalent plasma densities, while the ratio of the radius of the core part to the laser spot size, and the position of the peripheral part relative to the fixed core part were varied. The positive effects of this core-peripheral target structure could be expected from the knowledge of the typical target normal sheath acceleration (TNSA) mechanism in a laser-plasma interaction, and were apparently evidenced from the comparison with the case of a conventional simple planar target and the case of the transversal size reduction of the simple planar target. Improvements of the beam qualities including the collimation, the forward directionality, and the beam divergence were verified by detailed analysis of relativistic momentum, angular directionality, and the spatial density map of the accelerated protons.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.179-190
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• 2003

The grout based on solution type makes it difficult to get the improvement of ground strength and the effefct of water curtain because it has lower strength and durability than suspension type. Nowadays, the technology of particle acceleration, that enhance the material permeability, such as grout based on solution type, and inexpensive grout, is being required. For these reasons, in this study, using wet milling system, we evaluated physical properties of manufactured factors such as water-cement ratio of particles before being milled, optimum milling capacity by controlling milling time and rpm, viscosity of materials, permeation coefficient, and unconfined compressive strength. Also, using micro wet milling apparatus which could manufacture ordinary Portland cement and high speed shear mix which could forcefully separate conglomerate particles in situ, we performed electrical resistivity investigation and falling head permeability tests to analyze differences of grouting effects. From these results, we found that the permeability of the applied equipment was much superior, and in the case of using high speed shear mixer, particles of grout material were well separated.