• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.666-669
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• 2008

Droplet in miniaturized microfluidic systems have received much focused attention recently. In this work, electrical charging phenomenon of a conducting water droplet on the electrode under the dc electric field is studied and using this phenomenon droplet actuation method for microreactor applications is experimentally demonstrated. To find effects of key factors, the effects of electric field, medium viscosity, and droplet size are investigated. A scaling law of charging for the conducting droplet is derived from the experimental results. Unlike the case of a perfect conductor, the estimated amount of electrical charge ($Q_{est}$) of a water droplet is proportional to the 1.59 power of the droplet radius (R) and the 1.33 power of the electric field strength (E). (For a spherical perfect conductor, Q is proportional to R2 and E.) It is thought that the differences are mainly due to incomplete charging of a water droplet resulted from the combined effect of electrochemical reaction at electrode and the relatively low conductivity of water. Using this phenomenon, we demonstrate the transport of the charged droplet and fusion of two oppositely-charged droplets. When electric field is subjected sequentially on the electrode, the charged droplet is transported on the electrode. For the visualization of fusion of charged droplets, the precipitation reaction is used. When subjected to a DC voltage, two droplets charged are moving and merging toward each other due to the Coulombic force and chemical reaction is simultaneously occurred by coalescence of droplets. It may be due to the interchange effect of charge. It is shown that the droplet can be used for microreactor where transporting, merging etc. of reagents constitute unit operation.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.10
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• pp.421-426
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• 2019

In this paper, we propose a method to visualize the geometric features of the contact region between proteins in a protein complex. When proteins or ligands are represented as curved surfaces with irregularities, the property that the two surfaces contact each other without intersections is called shape compatibility. Protein-Protein or Protein-Ligand docking researches have shown that shape complementarity, chemical properties, and entropy play an important role in finding contact regions. Usually, after finding a region with high shape complementarity, we can predict the contact region by using residual polarity and hydrophobicity of amino acids belonging to this region. In the research for predicting the contact region, it is necessary to investigate the geometrical features of the contact region in known protein complexes. For this purpose, it is essential to visualize the geometric features of the molecular surface. In this paper, we propose a method to find the contact region, and visualize the geometric features of it as normal vectors and mean curvatures of the protein complex.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.201-206
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• 2006

Earth sciences is undergoing a gradual but massive shift from description of the earth and earth systems, toward process modeling, simulation, and process visualization. This shift is very challenging because the underlying physical and chemical processes are often nonlinear and coupled. In addition, we are especially challenged when the processes take place in strongly heterogeneous systems. An example is two-phase fluid flow in rocks, which is a nonlinear, coupled and time-dependent problem and occurs in complex porous media. To understand and simulate these complex processes, the knowledge of underlying pore-scale processes is essential. This paper presents a new attempt to use pore-scale simulations for understanding physical properties of rocks. A rigorous pore-scale simulator requires three important traits: reliability, efficiency, and ability to handle complex microstructures. We use the Lattice-Boltzmann (LB) method for singleand two-phase flow properties, finite-element methods (FEM) for elastic and electrical properties of rocks. These rigorous pore-scale simulators can significantly complement the physical laboratory, with several distinct advantages: (1) rigorous prediction of the physical properties, (2) interrelations among the different rock properties in a given pore geometry, and (3) simulation of dynamic problems, which describe coupled, nonlinear, transient and complex behavior of Earth systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.185-190
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• 2020

The rapid aging is increasing as the shortage of medical facilities and the resulting of decline in the quality of public health. In order to ease the burden of rising medical expenses, advanced medical institutions are expanding their remote medical care to lower the cost of services. U-healthcare detects the changes in physical and chemical phenomena occurring in the human body and converts them into electrical signals that can be processed and feeds back to the results through analytical and visualization processes to select only the desired information from the measured signals. The service is provided through a process of providing an alarm to a user. However, traditional biometric methods of attaching sensors directly to the body can be annoying and rejected in daily life. Therefore, there is a need for a method of continuously measuring biometric information without causing inconvenience to daily life. In this paper, we propose an IR-UWB-based non-contact and non-responsive respiratory measurement system that can continuously monitor biological information without any inconveniences to daily life.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.43-49
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• 2014

This experimental study has been conducted to scrutinize the effects of an ultrasonic standing wave (USW) on the propagating velocity and structure of methane/air premixed flame. Propagating flame was caught by high-speed Schlieren photography, and the variation of flame-behavior was analyzed in detail. It is revealed that horizontal splitting in burnt zone is resulted by the USW, and the flame propagation velocity is augmented due to the strengthened chemical reaction. Evolutionary feature of the flame perturbed by USW, maintaining a pseudo-symmetry of top and bottom flame-front about the propagation axis tends to be free from buoyancy effect.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.203-206
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• 1996

To understand the local fluid dynamics for different desists of Fontan operation, five models were made out of Pyrex glass to facilitate in-vitro study. Model I, II and III have same position of the center of the anastomosis of the IVC( inferior vena cava) with that of the SVC(superior vena cava), but Model IV and V have 10 mm offset between them. Also the anastomotic junction angles are different(Model I and $IV:90^{\circ}$, Model II and $V:70^{\circ}$, Model $III:45^{\circ}$). These models were then connected to a flow loop for flow visualization study. In Model I any dominant vortex was not seen in the central region of the juntion, but a large unstable vortex was created in the Model II and III. In Model IV and V a significant stagnation region was created in the middle of the offset region. It also showed that the flow direction from the IVC and SVC to the LPA(left pulmonary artery) and RPA(right pulmonary artery) highly depends on the offset of the junction rather than the anastomotic junction angle.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.700-704
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• 2015

As pH is a widely used index in chemical, medical, and environmental applications, research on pH sensors has been active in recent years. This study obtained RGB values by measuring the reflected light from a liquid sample to detect fine changes in pH, and performed mathematical modeling to investigate the relationship between the detected optical signal and pH value. Also, the trends in pH changes were easily identified by analyzing RGB values and displaying them in the color coordinate for easy visualization of data. This method implemented a user-friendly system that can measure and analyze in real time. This system can be used in many fields such as genetic engineering, environmental engineering, and clinical engineering, because it not only can measure pH but also replaces a colorimeter or turbidimeter.