• Membrane Journal
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• v.29 no.1
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• pp.61-65
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• 2019

Anisotropic particles have been issued in various fields due to their unique physical properties. Herein, a novel dynamic phase separation method (DPS) is introduced to fabricate anisotropic acorn-like nanoparticles. DPS consists of two dynamic conditions; solvent evaporation and nonsolvent induced precipitation. The bottom layer is controlled by feeding the water as a non-solvent diluent, and the phase separation of the upper layer relies on the diffusion and evaporation of a volatile good solvent. At this condition, the acorn-like particles were fabricated. Under a closed box filled with water (spontaneous phase separation), monodisperse polystyrene (PS) particles were synthesized. At the coexistence between DPS and spontaneous phase separation, the sizes of cap and particle were changed. Also, the volume of PS solutions influences on the particle shape. Since the unique structures could be utilized into various applications, if advanced techniques such as membrane-based controlled water feeding is developed, monodisperse acorn-like particles could be tuned.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.348-357
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• 2006

Ground Vibration Tests (GVT) are needed on au new aircraft types and as part of certification. Its first objective is to verify models used for the calculation and prediction of the dynamic behavior of the structure. The main objectives of this paper are to introduce 'the integrated approach of dynamic testing for aerospace structure' in detail and 'The research projects in which LMS participated in aerospace structural dynamic area'

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.33-41
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• 2011

A mathematical model of slip-in booster separation dynamics is described. A longitudinal 3-DOF(degree of freedom) 2-body dynamic model is developed to simulate the separation dynamics. Aerodynamic models of the missile and the exposed area of booster are built. And, gas generator pushing the booster out and internal channel pressure drop are modelled. To simulate the model, it is assumed that the missile can maintain the 1g level-fight condition during the separation. With this assumption, the interaction forces between missile and booster through the separation phases: phase 0: initial, phase 1: linear translation, and phase 2: free flight motion are defined. Using the simulation, missile flight conditions for slip-in booster`s safe separation, which can be represented by Mach vs. height envelope, are suggested.

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1707-1710
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• 2004

• Elastomers and Composites
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• v.43 no.3
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• pp.191-198
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• 2008

It is said that polymer modified asphalt using polyethylene as modifier would show phase separation due to density difference and incompatibility between asphalt and polyethylene. In this study, to prevent coalescence of polyethylene in asphalt, we employed peroxides as phase separation inhibitor. On microscope, peroxides (dicumyl peroxide, lauroyl peroxide) with waste vinyl (comprising low density polyethylene) did not show phase separation, however, rheometer test showed phase separation at molecular level, i.e., polyethylene and asphalt are immiscible ultimately. Mechanical properties (tensile strength, Marshall stability, dynamic stability) showed waste vinyl-modified asphalts are highly resistant to plastic deformation and these properties are even better than those of Superphalt.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.116-123
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• 2005

An experimental investigation on the static and dynamic stall characteristics of elliptic airfoil was performed by PIV velocity field measurements. The flow Reynolds number was $3.13{\times}10^5$ and the reduced frequency of the pitch oscillation ranged from 0.075 to 0.125. The onset of static stall was caused by boundary layer separation which started at the trailing edge and progressed toward the leading edge. However, dynamic stall was caused by the vortex shed at the leading edge region and the flow field showed a vortex dominated flow with turbulent separation and alternate vortex shedding. The increase of reduced frequency increased the dynamic stall angle of attack and intensified the flow hysteresis in the down-stroke phase.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.540-549
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• 2018

Classifying the front body of the missile and debris of a high-speed missile in intercepting a high-speed missile is an important issue. The motion of the front body of the missile is characterized by precession, but the motion of the debris in the boosting part separation phase is characterized by tumbling. There are periodic patterns caused by the precession or tumbling motion on the dynamic radar cross section (RCS). In addition, there are statistical properties caused by the change pattern of the dynamic RCS. A method is proposed to classify the front body of the missile and debris using periodic and statistical properties of the dynamic RCS. Three kinds of feature vector are extracted from the periodic and statistical properties of the dynamic RCS. The front body of the missiles and debris was classified using a support vector machine.

• Progress in Superconductivity
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• v.9 no.2
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• pp.140-145
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• 2008

We report on the Josephson vortex dynamics in $Bi_2Sr_2CaCuO_{8+\delta}$ natural Josephson junctions by c-axis tunneling measurements. Beside the quasiparticle branches in the current-voltage characteristics, a new set of multiple branches, referred to as Josephson-vortex-flow branches (JVFBs), are observed. The JVFBs emerge in an in-plane magnetic field above $H_0\;=\;{\Phi}_0/{\gamma}s^2$ and show highly hysteretic behavior, which can be explained in terms of the recently proposed dynamic-phase-separation model. In this work we examined the effect on the JVFBs by the presence of pancake vortices generated as the external magnetic field was applied slightly tilted from the in-plane direction. JVFBs were found to become larger and prominent with increasing pancake vortex density as the tilt angle increased, which were presumably caused by slowing down of a Josephson vortex lattice in the presence of pancake vortices.

• Membrane Journal
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• v.4 no.2
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• pp.85-95
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• 1994

This papr studies the dynamic effects of polyelectrolyte in the multilayered membrane. It is found that electrophoretic convection in the fluid phase can be used to accelerate the speed of the polyelectrolyte. The model in the membrane separation is studied via interactions between fluid and solid phases. The spectra evaluation using the operator theoretic method is performed for the parametric studies of the physical properties in the membrane process. The findings of this paper shoould be useful in guiding the design of separation devices. This paper shows one example for macroscopic study the theoretical review paper of membrane transport.

• Journal of the Korean Chemical Society
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• v.32 no.5
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• pp.452-457
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• 1988

Capacity factors (k') of some inorganic anions including $BF_4^{-1}$ were measured on cetylpyridinium coated column, and with dynamic system using tetrabutylammonium salicylate on PRP-1 reversed-phase column, respectively. After optimum separation condition was obtained this method was applied to the determination of boron in some different type samples.