• Journal of KSNVE
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• v.9 no.1
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• pp.60-69
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• 1999

In the first paper of this research$^{(1)}$. a new time series method. directional ARMAX (dARMAX) model-based approach. was proposed for rotordynamics identification. The dARMAX processes complex-valued signals, utilizing the complex modal testing theory which enables the separation of the backward and forward modes in the two-sided frequency domain and makes effective modal parameter identification possible. to account for the dynamic characteristics inherent in rotating machinery. In this second part. an evaluation of its performance characteristics based on both simulated and experimental data is presented. Numerical simulations are carried out to show that the method. a complex time series method. successfully implements the complex modal testing in the time domain. and it is superior in nature to the conventional ARMAX and the frequency-domain methods in the estimation of the modal parameters for isotropic and weakly anisotropic rotor systems. Experiments are carried out to demonstrate the applicability and the effectiveness of the dARMAX model-based approach, following the proposed fitting strategy. for the rotordynamics identification.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.55-56
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• 1994

There has been many attempts to improve the membrane performance using pervaporation processes[l-3]. They are 1) blending polymer with the high flux and one with high selectivity, 2) an incorporation of functional groups interacting with permeants into a membrane through copolymerization or modification, 3) composite membrane or asymmetric membrane structure with a thin skin layer which acts as a selective layer. Among them, a polymeric membrane containing ion complex group receives an extensive attention recently because ionic complex is known to activate the water transport through ion-dipole interaction. It is especially advantageous in the separation of organic-water system. We applied the ideas of the activation of water transport through ion-dipole. We have reported on the in-sire complex membrane to separate water from aqueous aceiic acid and pyridme solution[4-5] based on the simple acid-base theory. Water transport was enhanced through in-situ complex between pyridine moiety in the membrane and the incoming acetic acid in the feed. In this case, catalytic transport mechanism was proposed. In the present study we used pyridine solution as a feed and the sulfonic acid group in the membrane.

• Journal of the Korea Society of Computer and Information
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• v.14 no.7
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• pp.41-47
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• 2009

A solution to the problems of recognizing as one spot or detection failures for complex regions, in which many spots representing proteins are overlapped and saturated, is suggested. The accumulated gradients of each point in complex regions are calculated, and the resulting accumulated gradient image segmented using watershed technique. The suggested solution show better and efficient result than existing method for spot separation, detects more protein spots hidden in the image of 2-dimensional electrophoresis, and expands the scope of prediction.

• Analytical Science and Technology
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• v.12 no.6
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• pp.515-520
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• 1999

The spectrophotometric determination of Al(III) with thorin have been investigated. The optimum condition of pH, concentration of ligand and surfactant, and stability were evaluated. The thorin ligand offers selective separation of Al(III) from sample solution containing Fe(III), Ni(II), Cu(II), Pb(II) and Cu(II). Various surfactants were tested and Triton X-100 showed the best stability and the maximum absorbance in an aqueous solution of Al(III)-Thorin-Triton X-100 complex appears about 526 nm. The method was applied for the determination of Al(III) in mixed sample solution. Separation and preconcentration was performed with a short column filled with resorcinol-formaldehyde resin. Control of the pH during the column operation is essential because the adsorption capacities are very sensitive to change in pH. Their separation was carried out in 0.2 M acetic acid-sodium acetate buffer solution (pH 4.5) and 1.0 M $HNO_3$media.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2179-2188
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• 2015

Recently, many researches have been done to solve the challenging problem of Blind Source Separation (BSS) problems in the underdetermined cases, and the “Two-step” method is widely used, which estimates the mixing matrix first and then extracts the sources. To estimate the mixing matrix, conventional algorithms such as Single-Source-Points (SSPs) detection only exploits the sparsity of original signals. This paper proposes a new underdetermined mixing matrix estimation method for time-delayed mixtures based on the receiver prior exploitation. The prior information is extracted from the specific structure of the complex-valued mixing matrix, which is used to derive a special criterion to determine the SSPs. Moreover, after selecting the SSPs, Agglomerative Hierarchical Clustering (AHC) is used to automaticly cluster, suppress, and estimate all the elements of mixing matrix. Finally, a convex-model based subspace method is applied for signal separation. Simulation results show that the proposed algorithm can estimate the mixing matrix and extract the original source signals with higher accuracy especially in low SNR environments, and does not need the number of sources before hand, which is more reliable in the real non-cooperative environment.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.102-114
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• 2004

The present work has been developed the interpretation processor including the behavior of material failure and the separation phenomena under transient dynamic loading (the operation of explosive bolt) using AUTODYN V4.3, SoildWork 2003 and TrueGrid V2.1 programs. It has been demonstrated that the interpretation in ridge-cut explosive bolt under dynamic loading condition should be necessary to the appropriate failure model and the basic stress of bolt failure is the principal stress. The use of this interpretation processor developing the present work could be extensively helped to design the shape and the amount of explosives in the explosive bolt having a complex geometry. It is also proved that the interpretation processor approach is an accurate and effective analysis technique to evaluate the separation mechanism in explosive bolts.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.45-48
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• 2003

The plume interference is a complex phenomenon, consisting of plume-induced boundary layer separation, separated shear layer, multiple shock waves, and their interactions. The base knowledge of plume interference effect on powered missiles and flight vehicles is not yet adequate to get an overall insight of the flow physics in plume-freestream flow field. Computational studies are performed to better understand the flow physics of the plume-induced shock and separation for Simple, Rounded, Porous-extension test model configurations. The present study simulates highly underexpanded exhaust plume effect on missile body at the transoni $c^ersonic speeds. In order to investigate the plume-induced separation phenomenon, Simple, Rounded and Porous-extension plate are attacked to the missile afterbody. The computational result shows that the rounded afterbody and the porous-extension wall attached at the missile base can alleviate the plume-induced shock wave and separation phenomenon and improve the control of the missile body.dy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.100-108
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• 2017

Because of urbanization, Industrialization and expansion of transportation network, blasting works are recently increasing in construction field. The blasting work influences environmental effects to residents and the safety of facilities around the working place, so the development of blasting technology is needed to reduce the damage to residents. The blasting mechanism in the hole was studied and tested in the blasting sites by the difference of diameter between explosives and drilling hole, which is named by the decoupling effect. This effect was tested by changing the medium between explosives and hole wall in three working sites(railway, highway and industrial complex). The vibration velocity of blasting was recorded and vibration equations were produced by regression analyses. Finally, the structure separation distance was derived using these equations. The testing results show that the specific gravity of medium is larger, the separation distance is smaller and the duration time of blasting is shorter in case of large specific gravity of medium, so the vibration effect stops more fastly in the water compared with the air.

• Clean Technology
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• v.13 no.1 s.36
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• pp.79-84
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• 2007

Separation of ethylene from ethane and propylene from propane have been conducted using facilitated olefin transport membrane with SPEEK-Ag (Ag substituted sulfonated poly(ether ether ketone)). SPEEK was prepared by the sulfonation of PEEK using cone. $H_2SO_4$ and the reaction time affected the degree of sulfonation (DS) of the resulting SPEEK. SPEEK-Ag composite membrane was formed by soaking SPEEK in the polyester support into the Ag salt solution. With increasing the concentration of SPEEK in MeOH, the thickness of SPEEK on the polyester increased. The selectivity and the flux of SPEEK-Ag membrane for the separation of ethylene/ethane and propylene/propane were changed by the thickness of SPEEK layer on the top of polyester support. The anion of silver salt also affects the membrane performance.

• Journal of ILASS-Korea
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• v.25 no.4
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• pp.162-169
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• 2020

The worldwide focus on reducing the emissions, fuel and lubricant consumption in T-GDI engines is leading engineers to consider the crankcase ventilation and oil mist separation system as an important means of control. In today's passenger cars, the oil mist separation systems mainly use the inertia effect (e.g. labyrinth, cyclone etc.). Therefore, this study has investigated high efficiency cylinder head-integrated oil-mist separator by using a compact multi-impactor type oil mist separator system to ensure adequate oil mist separation performance. For this purpose, engine dynamometer testing with oil particle efficiency measurement equipment and 3D two-phase flow simulation have been performed for various engine operating conditions. Tests with an actual engine on a dynamometer showed oil aerosol particle size distributions varied depending on operating conditions. For instance, high rpm and load increases bot only blow-by gases but the amount of small size oil droplets. Submicron-sized particles (less than 0.5 ㎛) were also observed. It is also found that the impactor type separator is able to separate nearly no droplets of diameter lower than 3 ㎛. CFD results showed that the complex aerodynamics processes that lead to strong impingement and break-up can strip out large droplets and generate more small size droplets.