• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.1
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• pp.58-66
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• 2013

Most of steam power plant in Korea are heating the feed water system to prevent freezing water flowing in the pipe in winter time. The heating system is operated whenever the ambient temperature around the power plant area below 5 degree Centigrade. But this kind of heat supplying system cause a lot of energy consuming. If we think about the method that the temperature of the each pipe is controled by attaching the temperature measuring sensor like RTD sensor and heat is supplied only when the outer surface temperature of the pipe is under 5 degree Centigrade, then we can save a plenty of energy. In this study, the computer program package for simulation is used to compare the energy consumption load of both systems. Energy saving rate is calculated for the location of Youngweol area using the data of weather station in winter season, especially the January' severe weather data is analyzed for comparison. Various convection heat transfer coefficients for the ambient air and the flowing water inside the pipe was used for the accurate calculation. And also the various initial flowing water temperature was used for the system. Steady state analysis is done previously to approximate the result before the simulation. The result shows that the temperature control system using RTD sensor represents the high energy saving effect which is more than 90% of energy saving rate. Even in the severe January weather condition, the energy saving rate is almost 60%.

• Economic and Environmental Geology
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• v.29 no.3
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• pp.325-333
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• 1996

numerical model is developed to estimate gas flow in the landfill site. Darcy's law, the mass conservation law, and the ideal gas state equation are combined to compose the governing equation for the steady-state and transient-state gas flows. The finite element method (FEM) is used as the numerical solution scheme. Two-dimensional radial symmetric triangular ring element is used to discretize the simulation domain. The steady state model developed in this study is compared with AIRFLOW that is a commercial model developed by Hydrologic Inc. Mass balance test is performed on the transient gas flow simulation. The developed model is applied to analyze the gas extraction experiment performed by Daewoo Institute of Construction Technology at the Nanjido landfill in 1993. The developed model was registered at Korea Computer Program Protection Foundation.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.23-26
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• 2008

In order to examine the deformation characteristics of Al circular pipe underthe biaxial compression, the horizontal biaxial compression die for the experiment was manufactured. From this, in the various compressive strain rate (1 mm/min. ${\sim}$ 400 mm/min.)conditions, the circular pipes, which were made by Al materials, were investigated based on the properties change of cross section area, punch load and deformation behavior. The tensile and compressive strains were evaluated from micro Vickers hardness tester. From these results, the punch load and deformation characteristic of Al circular pipes were highly changed in the compressive strain rate about 200 mm/min. The Al circular pipes had the tendency that the punch load decreased with increasing the compressive strain rate. In addition, following as the change of the shape and position of neutral axis due to the deformation proceeding of the circular pipe, the special point of the internal circular pipe at maximum load showed the maximum deformation strain and the maximum measured hardness value. The CAE (computer aided engineering) simulation using Deform-2D program was performed on the circular pipe in order to know and verify the exact compressive deformation behavior. From these results, the experimentally measured results were reasonably in good agreement with the simulation results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.143-149
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• 2020

Currently, a multi-core processor is mainly used as a central processing unit of a computer system, and a high-performance out-of-order processor is adopted as each core to maximize system performance. The early out-of-order execution processor with Tomasulo algorithm aimed at floating-point instructions, and it took several cycles to execute by the use of complex structures such as reorder buffer and reservation station. However, in order for the processor to properly utilize out-of-order execution and increase the throughput of instructions, it must operate in a fully pipelined manner. In this paper, a fully pipelined out-of-order processor with speculative execution is designed with VHDL and verified with GHDL. As a result of the simulation, a program composed of ARM instructions is successfully performed.

• Ocean Systems Engineering
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• v.7 no.4
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• pp.435-460
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• 2017

The main objective of this study is to investigate the turning and zig-zag maneuvering performance of the well-known naval surface combatant DTMB (David Taylor Model Basin) 5415 hull with URANS (Unsteady Reynolds-averaged Navier-Stokes) method. Numerical simulations of static drift tests have been performed by a commercial RANS solver based on a finite volume method (FVM) in an unsteady manner. The fluid flow is considered as 3-D, incompressible and fully turbulent. Hydrodynamic analyses have been carried out for a fixed Froude number 0.28. During the analyses, the free surface effects have been taken into account using VOF (Volume of Fluid) method and the hull is considered as fixed. First, the code has been validated with the available experimental data in literature. After validation, static drift, static rudder and drift and rudder tests have been simulated. The forces and moments acting on the hull have been computed with URANS approach. Numerical results have been applied to determine the hydrodynamic maneuvering coefficients, such as, velocity terms and rudder terms. The acceleration, angular velocity and cross-coupled terms have been taken from the available experimental data. A computer program has been developed to apply a fast maneuvering simulation technique. Abkowitz's non-linear mathematical model has been used to calculate the forces and moment acting on the hull during the maneuvering motion. Euler method on the other hand has been applied to solve the simultaneous differential equations. Turning and zig-zag maneuvering simulations have been carried out and the maneuvering characteristics have been determined and the numerical simulation results have been compared with the available data in literature. In addition, viscous effects have been investigated using Eulerian approach for several static drift cases.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.469-472
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• 2004

This paper proposed and analyzed the Serial Piston Actuator(SPA) by using mechanical spring system coupled with linear actuator though the simplified structure which was verified practical experiments. The input voltage characteristics of a linear actuator are analyzed on the structure of the Linear Actuator Model System. Simulation and experimental result have been performed for the verification of the proposed system and the voltage characteristics applied to a actuator winding by electromechanical energy conversion theory. This paper proposed and analyzed the Linear Actuator Model(LAM) by using Matlab program with linear actuator was verified computer simulation based on the energy conversion theory.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.2
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• pp.77-82
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• 2016

The purpose of this paper is to develop the algorithm of human arousal inducing interface using steady-state visual evoked potential(SSVEP) and its verification through experiments. In order to develop the model, computer-based SSVEP program simulation is preliminary performed. From the results of the simulation, stimulus pattern is decided to checkerboard and SSVEP frequency range is set into beta wave (13~30Hz). After the experiment on proving the effect of SSVEP flashing stimulation while driving by installing it at the location of people mostly falling asleep in the highway, the result confirms that both during the night and the day, after SSVEP flashing stimulation, a wave Beta immediately increases and the subjects keep high stimulation for the 5 minute maintaining stage.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.797-805
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• 2002

The EV ROM, a joint reservoir operation model for flood control that accounts for the downstream flow condition, has been introduced in the preceding article (Shin et al, 2000). A joint reservoir operation model computer program for the Geum river basin, developed by FORTRAN Power Station 4.0 using the EV ROM, is hereby presented. Three case studies of flood control by joint operation of the Yongdam and Daechung Multipurpose Dams in the Geum river basin revealed that the performance of the EV ROM was superior to the existing Rigid ROM and Technical ROM. This is because the EV ROM can account for the downstream flow condition as well as the upstream inflow and the reservoir water level. In order to apply for various floods events in the future, consistent improvement of the developed EV ROM and efforts for more accurate rainfall prediction are required.

• Journal of the Korean Solar Energy Society
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• v.33 no.4
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• pp.23-30
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• 2013

This paper presents the determination method of the hybrid energy storage capacity for compensating the output of wind power when disconnecting from the grid. In the wind power output compensation, a lot of charging and discharging time with lithium-ion battery will be deteriorated the life time. And also, this fluctuation will cause some problems of the power quality and power system stability. To solve these kind of problems, many researchers in the world have been studied with BESS(Battery Energy Storage System) in the wind farm. But, BESS has the limitation of its output during very short term period, this means that it is difficult to compensate the very short term output of wind farm. Using the EDLC (Electric Double Layer Capacitor), it is possible to solve the problem. Installing the battery system in the wind farm, it will be possible to decrease the total capacity of BESS consisting of HESS (Hybrid Energy Storage System). This paper shows simulation results when not only BESS is connected to wind farm but also to HESS. To verify the proposed system, results of computer simulation using PSCAD/EMTDC program with actual output data of wind farms of Jeju Island will be presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.86-97
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• 2006

For the design of DC traction power supply system at new Light Rail Transit(LRT) construction, it is very important to determine system configuration, location and power capacity of substation. However, a LRT system consists of a number of subsystems such as train movement, power supply and traction drives, which inevitably contains many complexities and diversities. The objective of this paper is to clarify and systematize the design procedure and its assessment for the electrification system of a LRT line. This paper discusses in detail our approach to system design and its assessment. The whole DC-feeding network configuration, characteristics of a train, and design method of substation arrangements is thoroughly investigated for the design. As a result of the investigations, the design procedure is clarified and systematized and a computer program for the design and evaluation of the system is developed using the most suitable iterative method with nodal equation. To verify the proposed design and its assessment procedure, case studies for the DC traction power supply system of a planed Korean LRT line are performed.