• The Pure and Applied Mathematics
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• v.13 no.1 s.31
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• pp.1-10
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• 2006

The unsteady Hartmann flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to a constant pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the magnetic field and the uniform suction and injection on both the velocity and temperature distributions is examined.

• KIPS Transactions on Computer and Communication Systems
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• v.9 no.9
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• pp.197-206
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• 2020

Collaborative research in science applications based on HPC service needs rapid transfers of massive data between research colleagues over wide area network. With regard to this requirement, researches on enhancing data transfer performance between major superfacilities in the U.S. have been conducted recently. In this paper, we deploy multiple data transfer nodes(DTNs) over high-speed science networks in order to move rapidly large amounts of data in the parallel filesystem of KISTI's Nurion supercomputer, and perform transfer experiments between endpoints with approximately 130ms round trip time. We have shown the results of transfer throughput in different size file sets and compared them. In addition, it has been confirmed that the DTN cluster with three nodes can provide about 1.8 and 2.7 times higher transfer throughput than a single node in two types of concurrency and parallelism settings.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.273-283
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• 2008

GDL(Gas Diffusion Layer) is one of the main components of PEM fuel cell. It transports reactants from the channel to the catalyst and removes reaction products from the catalyst to the channels in the flow filed plate. It is known that higher permeability of GDL can make it possible to enhance the gas transport through GDL, leading to better performance. And MEA's temperature is determined by gas and heat transport. In this paper, three dimensional numerical simulation of PEM fuel cell of parallel channel and serpentine channel by the permeability of GDL is presented to analysis heat and mass transfer characteristics using a FLUENT modified to include the electrochemical behavior. Results show that in the case of parallel channel, performance variation with change of permeability of GDL was not so much. This is thought because mass transfer is carried out by diffusion mechanism in parallel channel. Also, in the case of serpentine channel, higher GDL permeability resulted in better performance of PEM fuel cell because of convection flow though GDL. And mass transfer process is changed from convection to diffusion when the permeability becomes low.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2290-2295
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• 2005

In this paper, it is developed simulator system of 3 D.O.F parallel robot for educate of expertness. This simulator system is composed of three parts ? 3 D.O.F parallel robot, controller (hardware) and software. First, basic structure of the robot is 3 active rotary actuator that small geared step motor with fixed base. An input-link is connected to this actuator, and this input-link can connect two ball joints. Thus, two couplers can be connected to the input-link as a pair. An end-plate, which is jointed by a ball joint, can be connected to the opposite side of the coupler. A sub-link is produced and installed to the internal spring, and then this sub-link is connected to the upper and bottom side of the coupler in order to prevent a certain bending or deformation of the two couplers. The robot has the maximum diameter of 230 mm, 10 kg of weight (include the table), and maximum height of 300 mm. Hardware for control of the robot is composed of computer, micro controller, pulse generator, and motor driver. The PC used in the controller sends commands to the controller, and transform signals input by the user to the coordinate value of the robot by substituting it into equations of kinematics and inverse kinematics. A controller transfer the coordinate value calculated in the PC to a pulse generator by transforming it into signals. A pulse generator analyzes commands, which include the information received from the micro controller. A motor driver transfer the pulse received from the pulse generator to a step motor, and protects against the over-load of the motor Finally, software is a learning purposed control program, which presents the principle of a robot operation and actual implementation. The benefit of this program is that easy for a novice to use. Developed robot simulator system can be practically applied to understand the principle of parallel mechanism, motors, sensor, and various other parts.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.657-664
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• 2011

This study proposes an inverse method for estimating the boundary temperature in a gas-filled, onedimensional parallel domain enclosed by parallel plates. The distance between the plates is considered submicron to one mm. In the current method, it is assumed that the conditions of both heat flux and temperature are simultaneously applicable to one boundary, while no conditions are applicable to the other boundary The temperature on one of the boundaries should be inversely determined from the known temperature and heat flux on the other boundary. This study proposes a procedure for estimating the unknown boundary temperature through Monte Carlo simulation. Both the forward and inverse problems employ the Monte Carlo approach. The forward (direct) problem is solved by using the direct simulation Monte Carlo while the inverse solution is obtained by the simulated annealing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.765-774
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• 1992

The effect of the interactive flow on convective heat transfer from two vertical isothermal parallel plates have been studied numerically by the finite difference method. The Reynolds number, Grashof number, the relative length, L$_{2}$/L$_{1}$, and the dimensionless plate spacing, b/L$_{1}$ are varied as parameters. In case of outside mean Nusselt number, left outside mean Nusselt numbers show same values as L$_{2}$/L$_{1}$ and b/L$_{1}$ increase, but right outside mean Nusselt numbers decrease as L$_{2}$/L$_{1}$ increases. The inside mean Nusselt numbers are constant at narrow spacings and increase at wide spacings as Grashof numbers increase. The optimun plate spacing on left inside mean Nusselt numbers is b/L$_{1}$=0.4 at Re=100 and b/L$_{1}$=0.3 at Re=200. For the right inside mean Nusselt number, the optimum plate spacings move to the narrow spacing as Reynolds numbers increase and L$_{2}$/L$_{1}$ decrease.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1335-1341
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• 2011

The purpose of this research is to investigate how separated and reattached flow affects mass transfer, by comparing the local mass transfer characteristics on an inclined flat plate with those on a parallel flat plate. The local mass transfer coefficients for the flat plate were measured using the naphthalene sublimation technique; the inclined angle of the flat plate was varied from $-10^{\circ}$ to $10^{\circ}$ at $5^{\circ}$ intervals, and the free-stream velocity was varied from 2m/s to 15m/s. At positive inclined angles, the local Sherwood numbers decreased gradually because the boundary-layer thickness increased. On the other hand, for negative inclined angles, the local Sherwood numbers assumed the minimum value at the separation point of the recirculation flow and the maximum value at the reattachment point. The average Sherwood numbers for both positive and negative inclined angles were lower than those in the case of the parallel plate.

• Proceedings of the Korean Society for Language and Information Conference
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• 2002.02a
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• pp.147-156
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• 2002

Aligned parallel corpora have proved very useful in many natural language processing tasks, including statistical machine translation and word sense disambiguation. In this paper, we describe an alignment technique for extracting transfer mapping from the parallel corpus. During building our system and data collection, we observe that there are three types of translation approaches can be used. We especially focuses on Traditional Chinese and Simplified Chinese text lexical translation and a method for extracting transfer mappings for machine translation.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.5
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• pp.412-417
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• 2016

A fin of finite width with infinitely small thickness is assumed to be placed horizontally between two horizontal parallel plates of infinite extension in the exactly central position. The lower plate and the half of the upper plate are kept at a constant lower temperature, and the remaining upper plate is kept at a constant higher temperature. The fin is also kept at a constant temperature (variable). Steady-state two-dimensional laminar natural convection is analyzed as a problem of boundary value under a boundary-fitted conformal mapping system, using a spectral finite difference scheme, with a condition of doubly-connectedness. The steady-state solution is obtained as a limit of the transient solution.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.910-915
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• 2009

For large reciprocating compressors in parallel operation, an analytical study has been carried out on the gas pulsation in associated discharge piping lines. Since the pressure pulsation at a valve, valve dynamics, and the gas flow rate through the valve are interrelated, affecting one another, these need to be solved simultaneously. Acoustic transfer matrix method, which relates acoustic pressure and velocity at one location to those at another location, has been adopted to calculate the effect of the gas flow at one valve location on the gas pulsation at other valve locations.