• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.7
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• pp.89-96
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• 2021

In this study, a mini hydro cyclone was designed and manufactured to achieve an inlet flow rate of 2 L/min in the experiment, which was conducted using alumina powder with a specific gravity of 3.97. This hydro cyclone was studied for using in steam and water analysis system (SWAS) of thermal power plant and was manufactured by 3D printing. Numerical analysis was performed with Solidworks Flow Simulation, utilizing the reynolds stress method (RSM) of fluid multiphase flow analysis models. Experimental and numerical analysis were performed under the three conditions of inlet velocity 2.0, 4.0, and 6.0 m/s. The separation efficiency was over 80% at all inlet velocity conditions. At the inlet velocity 4m/s, the separation efficiency was the best, and it was confirmed that the efficiency was more than 90%.

• Journal of KSNVE
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• v.8 no.3
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• pp.450-456
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• 1998

A rotordynamic analysis is performed with a centrifuge rotor-bearing system for the raing speed of 100,000 rpm. The system is composed of a centrifuge rotor(or simply the rotor), flexible shaft, motor rotor and shaft, and two support rolling element bearings of the motor shaft. Design goals are to achieve wide separation margins of critical speeds and favorable unbalance responses of the rotor at the associated critical speeds. The latter requirements are especially important as the system crosses multiple numbers of critical speeds and as the system may not have enough separaton margins around the rating speed. As the system adopts an extra-flexible shaft, it is shown that the rotor has satisfactory small unbalance responses over higher criticals while having an unsatisfactory large one at the first critical. To supress this a bumper ring or guide bearing needs to be installed at a suitable location of the flexible shaft. It is also shown that even with the flexible shaft the dynamics of the motor must be incoporated into the full system model to accurately identify the fourth critical speed, which is close to the rating speed, and higher ones. The analysis is based on the finite element method.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.717-720
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• 2003

A chromogenic biosensor employing microfluidics on a chip has been developed for the determination of high-density lipoprotein (HDL) cholesterol (HDL-C) in human serum. We have investigated a plain and effective method to immobilize enzymes within the microchip without chemically modifying micro-channel or technically micro-fabricating column reactor and fluid channel network. In assessing risk factors of coronary heart disease, a micro-chip system would minimize requirements of instrument and reagent handling.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.76.1-76
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• 2002

This paper addresses a method for nonlinear controller construction for a general nonlinear system with the separation of controller construction and manipulated values generation. The nonlinear system model is firstly expressed with the coefficients of state-depended representation. The nonlinear control is designed without any approximation based on the model with state-depended representation. At the stage of controller implementation for the nonlinear system, the manipulated values are calculated accurately by use of an algorithm of the numerical analysis. The numerical error for calculating the manipulated value can be reduced to zero by selecting the sampling interval being a small val...

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.369-380
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• 2011

This paper studies a boundary value problem for a linear coupled Luikov's system of heat and mass diffusion in one-dimensional case. Using an a priori estimate, we prove the uniqueness of the solution. Also, some traveling wave solutions and explicit solutions are obtained by using the transformation ${\xi}$ = x - ct and separation method respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.2
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• pp.174-185
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• 2004

Organic pollutants (Phenol, 2-Chlorophenol, Nitrobenzene) were separated from wastewater by nondispersive membrane solvent extraction, using a microporous hydrophobic hollow fiber module. The system was operated countercurrently and cocurrently with the aqueous phase flowing through the fiber lumens and the solvent flowing through the shell side. The distribution coefficients of several solvents (MIBK, IPAc, Hexane) were examined and MIBK was selected as an extracting solvent. Separation efficiency of countercurrent flow method was better than that of cocurrent flow method. Also, the overall mass transfer coefficients were determined.

• Nonlinear Functional Analysis and Applications
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• v.26 no.3
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• pp.513-530
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• 2021

The purpose of this paper is to introduce and study a class of coupled systems of fuzzy delay differential equations involving fuzzy initial values and fuzzy source functions of triangular type. We assume that these initial values and source functions are triangular fuzzy functions and define solutions of the coupled systems as a triangular fuzzy function matrix consisting of real functional matrices. The method of triangular fuzzy function, fractional steps and fuzzy terms separation are used to solve the problems. Furthermore, we prove existence and uniqueness of solution for the considered systems, and then a solution algorithm is proposed. Finally, we present an example to illustrate our main results and give some work that can be done later.

• Analytical Science and Technology
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• v.9 no.1
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• pp.52-61
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• 1996

Detectable levels of several free D-amino acids were found in some food. This was accomplished by using a column switching method. The determination of total amount of D- and L-amino acids was based on an achiral separation with a $C_{18}$ column. The level of D-amino acids to L-amino acids was determined by the column switching system including the postcolumn reaction detection of the amino acids derivatized with O-phthalaldehyde. The chiral separation of the postcolumn detection system was carried out with chiral crown ether column. This system was applied for the micro-determination of D-amino acids in food such as soy sauce, fermented soy bean and beans. It turned out that the sampling process is critical for the trace analysis of D-amino acids under this achiral / chiral coupled-column system. It was found that commercial soy sauce contained 42ppm, conventional soy sauce 102ppm, fermented soy bean 8.34mg per 1g and bean 2.87mg per 1g sample for phenylalanine. D-phenylalanine was found 0.67% in commercial soy sauce, 0.34% in conventional soy sauce, less than 1.81% in fermented soy bean, and Jess than 2.82% in bean.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.801-803
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• 2004

The current drive in an MOSFET is limited by the intrinsic channel resistance. All the other parasitic elements in a device structure playa significant role and degrade the device performance. These other resistances need to be less than $10{\%}-20{\%}$ of the channel resistance. To achieve the requirements, we should investigate the methodology of separation and quantification of those resistances. In this paper, we developed the extraction method of resistances using calibrated TCAD simulation. The resistance of the extension region is also partially determined by the formation of a surface accumulation region that forms under the gate in the tail region of the extension profile. This resistance is strongly affected by the abruptness of the extension profile because the steeper the profile is, the shorter this accumulation region will be.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.431-433
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• 2006

The goal of this paper is improvement of vision inspection accuracy by using histogram specification operation. The histogram is composed of horizontal axis of image intensity value and vertical axis of pixel number in image. In appearance vision inspection, the histogram of reference image and input image are different because of minutely lighting distinction. The minutely lighting distinction is main reason of vision inspection error in many cases. Therefore we made an effort for elevation of vision inspection accuracy by making the identical histogram of reference image and input image. As a result of this area separation histogram specification algorithm, we could increase the exactness of vision inspection and prevent system error from physical and spirit condition of human. Also this system has been developed only using PC, CCD Camera and Visual C++ for universal workplace.