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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 39, Issue 12 - Dec 2015
Volume 39, Issue 11 - Nov 2015
Volume 39, Issue 10 - Oct 2015
Volume 39, Issue 9 - Sep 2015
Volume 39, Issue 8 - Aug 2015
Volume 39, Issue 7 - Jul 2015
Volume 39, Issue 6 - Jun 2015
Volume 39, Issue 5 - May 2015
Volume 39, Issue 4 - Apr 2015
Volume 39, Issue 3 - Mar 2015
Volume 39, Issue 2 - Feb 2015
Volume 39, Issue 1 - Jan 2015
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Experimental Study of Micro-Shock Tube Flow
Park, Jin-Ouk ; Kim, Gyu-Wan ; Rasel, Md. Alim Iftakhar ; Kim, Heuy-Dong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 385~390
DOI : 10.3795/KSME-B.2015.39.5.385
The flow characteristics in micro shock tube are investigated experimentally. Studies were carried out using a stainless steel micro shock tube. Shock and expansion wave was measured using 8 pressure sensors. The initial pressure ratio was varied from 4.3 to 30.5, and the diameter of tube was also changed from 3mm to 6mm. Diaphragm conditions were varied using two types of diaphragms. The results obtained show that the shock strength in the tube becomes stronger for an increase in the initial pressure ratio and diameter of tube. For the thinner diaphragm, the highest shock strength was found among varied diaphragm condition. Shock attenuation was highly influenced by the diameter of tube.
Development of Standard ECG Simulator for 15-Lead ECG Monitor
Kang, Yu Min ; Lee, Jin Hong ; Choi, Seong Wook ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 391~395
DOI : 10.3795/KSME-B.2015.39.5.391
A 15-Lead ECG has been developed to diagnose posterior wall diseases of the heart that a 12-Lead ECG cannot diagnose. However, 15-Lead ECG data for developing heart-diseases-detecting algorithm are limited, and previous ECG simulators cannot predict the ECG waveform according to the changes in electrode. To solve these problems, the lumped parameter model (LPM), which divides the heart into 15 sections with varying electrical capacitance and electrical resistance. To imitate the electrical conduction in the heart, each node was connected to a current source and delivered the specific current considering the positions and time delay. The purpose of this study is to acquire the waveform that can be used in an ECG by delivering the specific current to LPM.
Measurement of Humidity Distribution in a Proton Exchange Membrane Fuel Cell Using Channel Embedded Humidity Sensors
Lee, Yongtaek ; Yang, Gyung Yull ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 397~403
DOI : 10.3795/KSME-B.2015.39.5.397
In this study, water distribution inside a proton exchange membrane fuel cell (PEMFC) was measured experimentally. Water distribution is non-uniform because of vigorous chemical reaction and mass transport and has been difficult to measure experimentally. Therefore, much research relied on indirect measuring methods or numerical simulations. In this study, several mini temperature-humidity sensors were installed at the channel for measuring temperature and humidity of the flowing gas throughout the channel. Only one of two electrode channels was humidified externally, and the humidity distribution on the other side was measured, enabling the observation of water transport characteristics under various conditions. Diffusion through the membrane became more vigorous as the temperature of the humidifier rose, but at high current density, electro-osmotic drag became more effective than diffusion.
Numerical Analysis of the Movement of an Initially Hemispherical Droplet on Hydrophilic/Hydrophobic Surfaces
Myong, Hyon Kook ; Kwon, Young Hoo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 405~414
DOI : 10.3795/KSME-B.2015.39.5.405
Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources and numerically validated the results for a hypothetical 2D, initially having a hemicylindrical droplet. In this paper, the movement of an actual water droplet, initially having a 3D hemispherical shape, on horizontal hydrophilic/hydrophobic surfaces is simulated using a commercial computational fluid dynamics (CFD) package, Fluent, with VOF (volume of fluid) method. The results are compared with the 2D analysis of Myong (2014), and the transport mechanism for the actual water droplet is examined based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, surface free and pressure energies inside the droplet.
Grid Refinement Model in Lattice Boltzmann Method for Stream Function-Vorticity Formulations
Shin, Myung Seob ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 415~423
DOI : 10.3795/KSME-B.2015.39.5.415
In this study, we present a grid refinement model in the lattice Boltzmann method (LBM) for two-dimensional incompressible fluid flow. That is, the model combines the desirable features of the lattice Boltzmann method and stream function-vorticity formulations. In order to obtain an accurate result, very fine grid (or lattice) is required near the solid boundary. Therefore, the grid refinement model is used in the lattice Boltzmann method for stream function-vorticity formulation. This approach is more efficient in that it can obtain the same accurate solution as that in single-block approach even if few lattices are used for computation. In order to validate the grid refinement approach for the stream function-vorticity formulation, the numerical simulations of lid-driven cavity flows were performed and good results were obtained.
Direct-current Dielectrophoretic Motions of a Single Particle due to Interactions with a Nearby Nonconducting Wall
Kang, Sangmo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 425~433
DOI : 10.3795/KSME-B.2015.39.5.425
In this paper, we have numerically investigated two-dimensional dielectrophoretic (DEP) motions of a single particle suspended freely in a viscous fluid, interacting with a nearby nonconducting planar wall, under an externally applied uniform direct-current electric field. Particularly, we solve the Maxwell equation with a large sharp jump in the electric conductivity at the particle-fluid interface and then integrate the Maxwell stress tensor to compute the DEP force on the particle. Results show that, under an electric field parallel to the wall, one particle is always repelled to move far away from the wall and the motion depends strongly on the particle-wall spacing and the particle conductivity. The motion strength vanishes when the particle is as conductive as the fluid and increases as the conductivity deviates further from that of the fluid.
Shape Optimization of High Power Centrifugal Compressor Using Multi-Objective Optimal Method
Kang, Hyun Su ; Lee, Jeong Min ; Kim, Youn Jea ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 435~441
DOI : 10.3795/KSME-B.2015.39.5.435
In this study, a method for optimal design of impeller and diffuser blades in the centrifugal compressor using response surface method (RSM) and multi-objective genetic algorithm (MOGA) was evaluated. A numerical simulation was conducted using ANSYS CFX with various values of impeller and diffuser parameters, which consist of leading edge (LE) angle, trailing edge (TE) angle, and blade thickness. Each of the parameters was divided into three levels. A total of 45 design points were planned using central composite design (CCD), which is one of the design of experiment (DOE) techniques. Response surfaces that were generated on the basis of the results of DOE were used to determine the optimal shape of impeller and diffuser blade. The entire process of optimization was conducted using ANSYS Design Xplorer (DX). Through the optimization, isentropic efficiency and pressure recovery coefficient, which are the main performance parameters of the centrifugal compressor, were increased by 0.3 and 5, respectively.
Flow Analyses of Upper Airway Before and After Maxillomandibular Advancement Surgery for Obstructive Sleep Apnea Patient
Kim, Hyoung-Ho ; Suh, Sang-Ho ; Choi, Jin-Young ; Kim, Taeyun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 443~448
DOI : 10.3795/KSME-B.2015.39.5.443
Obstructive sleep apnea (OSA) is a syndrome characterized by the repetitive episodic collapse of the upper airway. Maxillomandibular advancement surgery is one of the most effective surgical treatment methods in treating obstructive sleep apnea. The advancement of both maxill and mandible can enlarge the cross-sectional areas and volumes of the postero-superior airway. The purpose of this study is to analyze flow patterns in the upper airway before and after maxillomandibular advancement surgery. Here, we analyzed flow phenomena of inspiration and expiration to prevent obstructive sleep apnea patient from happening side effect. Modeling of the upper airway carried out from clinical CT scanned images. We used time-dependent values for boundary condition. CFD analyses were performed and evaluated section of minimum area (SMA), compared with patient inside upper airway before and after maxillomandibular advancement surgery in SMA, and negative pressure effects. The study showed the greatest enlargment of the section of minimum cross-sectional area. Moreover, the velocity and the negative airway pressure were decreased. According to the result of this study, the maxillomandibular advancement surgery stabilizes the airflow in the postero-superior airway of OSA patients.
Interfacial Behavior of Water Droplet on Micro-Nano Structured Surfaces
Kwak, Ho Jae ; Yu, Dong In ; Kim, Moo Hwan ; Park, Hyun Sun ; Moriyama, Kiyofumi ; Ahn, Ho Sun ; Kim, Dong Eok ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 449~453
DOI : 10.3795/KSME-B.2015.39.5.449
Recently, surfaces with micro and nano structures are the focus of various research and engineering fields to enhance wetting characteristics of the surfaces. Hydrophilic surfaces with hierarchical structures are generally characterized by the interfacial behavior of water droplets. In this study, the interfacial behavior of water droplets is experimentally investigated considering the scale of structures. Using the dry etching and conventional lithography method, quantitative hierarchical structured surfaces are developed. The behavior of the liquid-vapor interface on the test sections is visualized using an automatic goniometer and a high-speed camera. On the basis of the visualized data, the interfacial behavior of water droplets is intensively investigated according to surface geometrical characteristics.
A Study of the Fluidic Characteristics of High-Pressure Fuel Pumps for GDI Engines
Lee, Sangjin ; Noh, Yoojeong ; Liu, Hao ; Lee, Jae-Cheon ; Shin, Yongnam ; Park, Yongduk ; Kang, Myungkweon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 455~461
DOI : 10.3795/KSME-B.2015.39.5.455
A high-pressure fuel pump is a key component in a gasoline direct injection (GDI) engine; thus, understanding its flow characteristics is essential for improving the engine power and fuel efficiency. In this study, AMESim, which is a hydraulic analysis program, was used to analyze the performance of the high-pressure fuel pump. However, since AMESim uses a one-dimensional model for the system analysis, it does not accurately analyze the complicated flow characteristics. Thus, Fluent, computational fluid dynamics (CFD) software, was used to calculate the flow rates and net forces at the intake and discharge ports of the high-pressure fuel pump where turbulent flow occurs. The CFD analysis results for various pressure conditions and valve lifts were used as look-up tables for the AMEsim model. The CFD analysis results complemented the AMEsim results, and thus, improved the accuracy of the performance analysis results for the high-pressure fuel pump.
Development and Analysis of Graphene Oxide Thin Film Coating
Cheon, Yeong Ah ; Nam, Jin-Su ; Son, Kyung Soo ; Im, Young Tae ; Ahn, Won Kee ; Chung, Bong Geun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 39, issue 5, 2015, Pages 463~469
DOI : 10.3795/KSME-B.2015.39.5.463
In this study, we synthesized graphene oxide and developed novel spin-spray coating technology. The graphene oxide thin film was uniformly coated on amine-functionalized glass surfaces using spin-spray coating technology. We also stacked up to four layers of graphene oxide on glass substrates in a uniform manner. From the results, we infer that this spin-spray coating of graphene oxide thin film could be a powerful tool for various electronic display coating applications.