• Korean Journal of Materials Research
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• v.21 no.1
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• pp.39-45
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• 2011

In this study, the heat flow of the plant scale aluminum extrusion process was investigated to establish optimum continuous heat treatment conditions. During the extrusion of 6061 aluminum alloy, processing parameters such as the extrusion pressure, speed and temperature histories of billets were logged as a function of time. The surface temperature of the billets increased at constant ram speed, while it decreased with decreases of the ram speed. In order to maintain the billet temperature within a solutionizing temperature range prior to the succeeding water quenching step, the ram speed or the temperature of the blower should be controlled. The temperature histories of the billets during the extrusion and hot air blowing processes were successfully simulated by using the velocity boundary model in ANSYS CFX. The methodology to design an optimum process by using a commercial simulation program is described in this study on the basis of the metallurgical validation results of the microstructural observation of the extrudates. The developed model allowed the advantages of taking into account the motion of the extrudate coupled with the temperature change based on empirical data. Calculations were made for the extrudate passing through the isothermal chamber maintained at appropriate temperature. It was confirmed that the continuous heat treatment system is beneficial to the productivity enhancement of the commercial aluminum extrusion industry.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.8
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• pp.544-554
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• 2014

In this paper, we introduce a cyber-physical intersection systems (CPIS) which intimately interconnects roadside units (RSU) located at intersection, on-board units (OBU) of moving vehicles, and smartphone apps. Based on the architecture of CPIS, we also present a green light optimal speed advisory based on the reference mobility models (GLOSA-RMM) to reduce intersection stopping time (IST) and fuel consumption. Based on several reference mobility models, the GLOSA-RMM determines the appropriate speed advisory by taking into account the current mobility and the intersection traffic light status, and then provides screen/voice GLOSA instructions to minimize the driver's distraction. We show that the GLOSA-RMM can reduce both the IST and the fuel consumption through the numerical results obtained from the prototype of the CPIS consisting of the OBU, the RSU and the smartphone app.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.814-819
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• 2005

There is growing consciousness of the environmental performance of buildings in Hong Kong. The Buildings Department, the Lands Department and the Planning Department of the Hong Kong Government issued the first of a series of joint practice notes [1] to promote the construction of green and innovative buildings. Green features are architectural features used to mitigate migration of noise and various air-borne pollutants and to moderate the transport of heat, air and transmission of daylight from outside to indoor environment in an advantageous way. This joint practice note sets out the incentives to encourage the industry in Hong Kong to incorporate the use of green features in building development. The use of green features in building design not only improves the environmental quality, but also reduces the consumption of non-renewable energy used in active control of indoor environment. Larger window openings in the walls of a building may provide better natural ventilation. However, it also increases the penetration of direct solar radiation into indoor environment. The use of wing wall, one of the green features, is an alternative to create effective natural ventilation. This paper therefore presents a preliminary numerical study of its ventilation performance using Computational Fluid Dynamics (CFD). The numerical results will be compared with the results of the wind tunnel experiments of Givoni.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.4
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• pp.73-83
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• 2004

With increasing numbers of vehicles on restricted roads, It happens that we have much wasted time and decreased average car speed. This paper proposes a new concept of coordinating green time which controls 10 traffic intersection systems. For instance, if we have a baseball game at 8 pm today, traffic volume toward the baseball game at 8 pm today, franc volume toward the baseball game will be increased 1 hour or 1 hour and 30 minutes before the baseball game. At that time we can not predict optimal green time Even though there have smart electro-sensitive traffic light system. Therefore, in this paper to improve average vehicle speed and reduce average vehicle waiting time, we created optimal green time using fuzzy rules md neural network as a preprocessing. Also, we developed an Intelligent PLC(Programmable Logic Controller) for real time traffic forecasting as a postprocesing about unexpectable conditions. Computer simulation results proved reducing average vehicle waiting time which proposed coordinating green time better than electro-sensitive franc light system does not consider coordinating green time.

• Textile Coloration and Finishing
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• v.8 no.5
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• pp.7-16
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• 1996

The air-flow dyeing machine is a new type of dyeing machine. Which is an energy saving type to be able to dye the fabrics with the lowest liquor ratio and in shorter time. This machine is operated with an aerodynamic system rather than a hyd raulic system for traditional jet or overflow dyeing. An air-flow dyeing machine(Green-flow) by the use of aerodynamic technology was developed and compared with the Luft-roto machine made by Thies Company, Germany, in this study. Three samples were dyed with both machines under the same dyeing conditions and color fastness, dyeing levelness, drapability, and mechanical properties of these samples were compared. The results were as follows; Both machines have almost the same dyeability. The dyeability was good at liquor ratio of 1: 3.5 and the speed of 450yds/min. The order for drapability was Crepe de Chine > Cool Peach > Charmeuse. Except for the color fastness of sublimation being below class 4, most color fastness of samples dyed with Green-flow m/c were above class 4. The maximum speed was 510yds/min. for Crepe de Chine and the standard deviation of K/S value was lower for Charmeuse and Cool Peach when employed on the "Green-flow" machine and lower for Crepe de Chine when employed on the Luft-roto machine. Comparing with dyeing of the Green-flow machine and that of the Luft-roto machine, the RT of the Charmeuse was found to be higher with the Green-flow machine and thus the sample had an improved wrinkle recovery. LT and WT of Cool Peach were higher, and shear properties(G, 2HG, 2HGS) of Crepe de Chine were higher, both turning out as suitable for clothing. clothing.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.489-494
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• 2015

As the world-wide supply of fossil fuel sources decreases, the need for efficient energy conservation in addition to developing green energy technologies becomes critical. Wind energy is now regarded as one of the most rapidly expanding energy sources in the world. However, due to the high cost for the foundation of large turbines and the high wind speed (over 12 m/s) required, it is very difficult to establish inland wind power plants. In order to solve issues mentioned above, experiments were performed using the small wind power system operated in a low wind speed. In this research, inland wind condition was first analyzed, and 300 W and 1 kW small wind power generators were then installed on a roof and efficiencies of generating electricities were compared.

• New & Renewable Energy
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• v.10 no.3
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• pp.14-21
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• 2014

As the world supply of fossil fuel sources decreases, the need for efficient energy consevation and develping green energy technologies becomes critical. Because of the high cost of the foundation for large turbines and optional high wind speed (over 12 m/s), it is very difficult to be located at inland city. For the solution above mentioned problem, we have been experimented about that not only using the adaption of wind power system on buildings for improving turbine efficiency, but also applying a wound rotor type induction generator for a small wind turbine.In this research, we try to find out the wind direction and wind speed those were measured every 1 min., during operation period, using the anemometers which consist of horizontally spinning cups on a vertical post. Performance testing for small wind turbine generating system was carried out by using the induction motor and invertor. Finally, we measured the power of 1 kW wind turbine system with the clamp meter and a voltmeter.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.6 s.144
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• pp.559-565
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• 2005

As the wave impinges on and overtops the structure, a large highly aerated region is created in front of the structure and water splashs on top of the structure. The broken wave in front of the structure and associated green water on top of the structure are highly aerated containing not only a large number of bubbles but also very large sizes of bubbles. In this paper, the velocity field of the highly aerated region and the splashing water on the top is measured using a modified PIV method incorporating the traditional PIV method with the shadowgraphy technigue by correlating the ' texture ' of the bubble images. The velocity fields of a plunging wave impacting on a structure in a two-dimensional wave flume is measured. It is found that the maximum fluid particle velocity in flout of the structure during the impinging process is about 1.5 times the phase speed of the wave, while the maximum horizontal velocity above the top is less than the phase speed, It is also found that the dam breaking solution does not work well in predicting the green water velocity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.288-291
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• 2003

This paper presents an extended Twyman-Green interferometry that enables simultaneous and real-time measurement of 5-DOF motion errors of the translational moving stage. This method uses a null balancing technique in which two plane mirrors are used as target mirrors to generate an interferometric fringe utilizing the optical principles of Twyman-Green interferometry. Fringe is detected by 2D photodiode array for high-speed measurement. Errors are then independently suppressed by activation of piezoelectric actuators through real-time feedback control while the machine axis is moving. Experimental results demonstrate that a machine axis can be controlled with motion errors about 10 nm in linear displacement, 0.15 arcsec in angular displacement

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.112-119
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• 2003

This paper presents an extended Twyman-Green interferometry that enables simultaneous and real-time measurement of 5-DOF motion errors of the translational moving stage. This method uses a null balancing technique in which two plane mirrors are used as target mirrors to generate an interferometric fringe utilizing the optical principles of Twyman-Green interferometry. Fringe is detected by 2D photodiode array for high-speed measurement. Errors are then independently suppressed by activation of piezoelectric actuators through real-time feedback control while the machine axis is moving. Experimental results demonstrate that a machine axis can be controlled with motion errors about 10 nm in linear displacement, 0.15 arcsec in angular displacement.