• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.1
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• pp.79-88
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• 2014

We have developed a smart decontamination device for small-size radioactive scrap metal (SSRSM) necessarily generated from nuclear facilities. This is a multi-modal device such as rotation of magnetic field focusing on the region containing the abrasion pins placed around target and ultrasonic cleaner. Additionally, in order to increase the decontamination efficiency we have modified some configuration of the device so that it could work on them evenly and totally. With the Optimal operating for operation of the new device, we tried to decontaminate some various metal selected as a sample during 15 minutes sequentially using each method, magnetic and ultrasonic device. As a result, the range of decontamination factor has been highly increased to 18~56. After decontamination, all samples were found its activity less than background level.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.38-45
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• 2004

This paper studies the effects of intake port configuration on the swirl that is key parameter in the flow field of direct injection diesel engines. In-cylinder flow characteristics is known to have significant effects on fuel air mixing, combustion and emissions. To investigate the swirl flow generated by various intake ports, steady state flow tests were conducted to evaluate the swirl. Helical port geometry, SCV shape and bypass were selected as the design parameters to increase the swirl flow and parametric study was performed to choose the optimal port shape that would generate a high swirl ratio efficiently. The results revealed that a key factor in generating a high swirl ratio was to suitably control the direction of the intake air flow passing through the valve seat. For these purposes, we changed the distance of helical and tangential port as well as installed bypass near the valve seat and the effects of intake port geometry on in-cylinder flow field were visualized by a laser sheet visualization method. From the experimental results, we found that the swirl ratio and mass flow rate had a trade off relation. In addition, the result indicates that the bypass is a effective method to increase the swirl ratio without sacrificing mass flow rate.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.279-288
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• 2015

Using the Vehicle Modeling Function, which can model various 3D nose shapes, nose shape optimization is performed to reduce the aerodynamic drag of the KTX Sancheon. 2D characteristic shapes of the KTX Sancheon nose were extracted and a base model of the KTX Sancheon was constructed for design optimization using the Vehicle Modeling Function. The design space was constructed with the base model and does not violate the shape constraints of commercial trains. Through nose shape optimization with the Broyden-Fletcher-Goldfarb-Shanno algorithm, the aerodynamic drag of the optimized shape was reduced by 6% compared to that of the base model. The longer nose and sharper edge of the optimized shape weaken the vortices behind the last car and can reduce the aerodynamic drag.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.127-136
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• 2008

This paper proposes the efficient system for automatic design of FSS(Frequency Selective Surface) with periodic pattern and frequency characteristics specified by operator. The proposed system derives optimal design parameters through tool for analysis of FSS with arbitrary pattern, DB(Data Base) implemented from limited simulation and measurement data of FSS, and GA(Genetic Algorithm) for optimizing design parameters. FSS analysis tool consists of two analysis tools. One is the simulator for analysis of monolayer FSS that using moment method, another is the tool with approximated analysis method of FSS with dielectric layer. Given pattern configuration and characteristics specified by operators, the DB system searches the best matching FSS, and provides initial genes to GA from the searched parameters, which drastically reduces running time of GA for finding the FSS design parameters. In this paper, the proposed design system is verified through simulation and measurement about FSS with various patterns.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.39-45
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• 2007

This paper proposed a shortcut method for the structure design of dividing wall column based on the Fen-ske-Underwood equation by applying it on three conventional simple column configuration. It is shown that the proposed shortcut method can design the column structure including the feed tray, dividing wall section, and side-stream tray in a simple and efficient way in the initial design stage. Simulation study using HYSYS to compare the energy saving performance between the conventional sequential two column system and the dividing wall column designed by the proposed method shows that the proposed dividing wall column system saves from 16% to 65% more over the condepends on the composition of intermediate component while the optimal energy consumption pattern to internal flow distribution on the dividing wall section is characterized by the ESI factor of the feed mixture.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.3
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• pp.206-215
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• 2005

In this paper, we propose a new design method of Genetic Algorithm Processor(GAP) and Evolvable Hardware(EHW). All sorts of creature evolve its structure or shape in order to adapt itself to environments. Evolutionary Computation based on the process of natural selection not only searches the quasi-optimal solution through the evolution process, but also changes the structure to get best results. On the other hand, Genetic Algorithm(GA) is good fur finding solutions of complex optimization problems. However, it has a major drawback, which is its slow execution speed when is implemented in software of a conventional computer. Parallel processing has been one approach to overcome the speed problem of GA. In a point of view of GA, long bit string length caused the system of GA to spend much time that clear up the problem. Evolvable Hardware refers to the automation of electronic circuit design through artificial evolution, and is currently increased with the interested topic in a research domain and an engineering methodology. The studies of EHW generally use the XC6200 of Xilinx. The structure of XC6200 can configure with gate unit. Each unit has connected up, down, right and left cell. But the products can't use because had sterilized. So this paper uses Vertex-E (XCV2000E). The cell of FPGA is made up of Configuration Logic Block (CLB) and can't reconfigure with gate unit. This paper uses Vertex-E is composed of the component as cell of XC6200 cell in VertexE

• The Journal of the Acoustical Society of Korea
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• v.30 no.2
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• pp.63-72
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• 2011

Since the detection probability is critically dependent on the target strength (TS) in active sonar and on the radiated noise level (RNL) in passive sonar, the acoustic materials for echo reduction (ER) and transmission loss (TL) are widely used for the stealth of underwater targets. In this paper, a measurement system based on the small water tank, for the frequency range of greater than 30 kHz, is developed and verified using reference targets. In order to design the water tank and the geometry of test samples, a program is developed to calculate the arrival time of interfering signals due to the reflection from water tank walls and also due to the diffraction from the edge of the test samples. Considering all the interfering signals, an optimal experimental configuration for water tank and test samples is designed and used throughout the experiment. Next, the signal processing algorithms to estimate ER and TL are developed based on the measured propagation loss reflecting the geometric spreading characteristics of the transducer. Finally, a set of reference targets such as aluminium plate and perfectly reflecting plate are used in a small water tank to verify the developed measurement system.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.30-37
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• 2013

A ground hot-firing test was conducted to take out the optimal design configurations for the catalyst bed of liquid-monopropellant hydrazine thruster which could be used for primary engine or attitude control thruster of space vehicles. Performance characteristics with the variation of thrust-chamber length are investigated in terms of thrust, specific impulse, chamber pressure, characteristic velocity, and hydrazine decomposition rate. Additionally, the correlations between propellant-supply pressure and performance parameters are given. As results, increase of catalyst-bed length leads to performance degradation in this test condition, and also decreases propellant consumption efficiency with the supply pressure variation.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.47-56
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• 2002

The office is an excellent candidate for implementing daylighting techniques because of the relatively high electric lighting power densities and long daytime use pattern. The quantity of light available for a space can be translated in term of the amount of energy savings through a process of a building energy simulation. To get significant energy savings in general illumination, the electric lighting system must be incorporated with a daylight - activated dimmer control. A prototype configuration of an office interior has been established and the integration between the building envelope and lighting and HVAC systems is evaluated based on computer modeling of a lighting control facility. First of all, an energy-efficient luminaire system is designed for both a totally open-plan office interior and a partitioned office. A lighting design and analysis program, Lumen-Micro 2000 predicts the optimal layout of a conventional fluorescent lighting fixture to meet the designed lighting level and calculates unit power density, which translates the demanded amount of electric lighting energy. A dimming control system integrated with the contribution of daylighting has been applied to the operating of the artificial lighting. Annual cooling load due to lighting and the projecting saving amount of cooling load due to daylighting under overcast diffuse sky are evaluated by a computer software, ENER-Win. In brief, the results from building energy simulation with measured daylight illumination levels and the performance of lighting control system indicate that daylighting can save over 70 percent of the required energy for general illumination in the perimeter zones through the year. A 25 % of electric energy for cooling may be saved by dimming and turning off the luminaires in the perimeter zones.

• Journal of Korea Water Resources Association
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• v.44 no.6
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• pp.477-486
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• 2011

The objective of this study is to investigate the water pollution problems brought about by the construction of eco-friendly waterfront space through the physical model experiment including water quality consideration. Due to the lack of water supply into the artificial ponds and canals, the water quality problems such as eutrophication, odor and so on can be occurred. There have been many numerical models on such phenomena but limited studies using physical test due to the difficulty in the verification of physical interpretation of the study area. In this study, a prototype model that is not affected by the dimensionless parameters was carried out, where unpolluted water is mixed into the contaminated water to reduce the concentration of nutrients. In addition, this study also attempt to find the optimal configuration of the flow induction machines using the scale model which will evaluate and verify the effectiveness of the enforcement methods to maintain the water quality objectives.