• Membrane and Water Treatment
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• v.7 no.3
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• pp.175-191
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• 2016

In this work, oil-in-water emulsions (O/W) were prepared successfully by membrane emulsification with $0.5{\mu}m$ pore size membrane. Sunflower oil was emulsified in aqueous Tween80 solution with a simple crossflow apparatus equipped with ceramic tube membrane. In order to increase the shear-stress near the membrane wall, a helical-shaped reducer was installed within the lumen side of the tube membrane. This method allows the reduction of continuous phase flow and the increase of dispersed phase flux, for cost effective production. Results were compared with the conventional cross-flow membrane emulsification method. Monodisperse O/W emulsions were obtained using tubular membrane with droplet size in the range $3.3-4.6{\mu}m$ corresponded to the membrane pore diameter of $0.5{\mu}m$. The final aim of this study is to obtain O/W emulsions by simple membrane emulsification method without reducer and compare the results obtained by membrane equipped with helix shaped reducer. To indicate the results statistical methods, $3^p$ type full factorial experimental designs were evaluated, using software called STATISTICA. For prediction of the flux, droplet size and PDI a mathematical model was set up which can describe well the dependent variables in the studied range, namely the run of the flux and the mean droplet diameter and the effects of operating parameters. The results suggested that polynomial model is adequate for representation of selected responses.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2275-2278
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• 2005

In this paper, a control algorithm for a servo manipulator is focused on. A servo manipulator system has been developed for remotely handling radioactive materials in a hot cell. It is driven by servo motors. The torque from a servo motor is transferred through a reducer to the corresponding axis. The PID control algorithm is a simple and effective algorithm for such application. However, since friction degrades the algorithm's performance, friction has to be considered and compensated. The major aberrations are the positional tracking errors and the limit cycle. The authors have considered a switching term to a conventional PID algorithm to reduce the friction's effect. It has been tested by a hardware test.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.143-149
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• 2002

Ball reducer with waved grooves has many advantages over other reducers for the high-reduction ratios, low noise and low energy loss, etc. The mechanism of force transmission is very similar to that of cam and follower in automobile valve train system especially in the contact geometry. In this study, we have investigated the traces of contact between ball and outer race and the working behaviors with a certain reduction ratio. In order to verify the contact behaviors between ball and outer race, which determines the critical endurance life the contact velocity and load are computed for a cycle. During some period of a cycle, the contact velocity reverses its direction very suddenly, which causes undesirable endurance performance of this machinery. From the computational investigation in this work, we hope to predict similar contact damages in other machinery due to this kind of contact behaviors, which is very common in many contact phenomena.

• Nuclear Engineering and Technology
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• v.42 no.1
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• pp.73-78
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• 2010

The suppression of molten salt vaporization is one of the key technical issues in the electrolytic reduction process developed for recycling spent nuclear fuel from light-water reactors Since the Hertz-Langmuir relation previously applied to molten salt vaporization is valid only for vaporization into a vacuum, a diffusion model was derived to quantitatively assess the vaporization of LiCl, $Li_2O$ and Li from an electrolytic reducer operating under atmospheric pressure. Vaporization rates as a function of operation variables were calculated and shown to be in reasonable agreement with the experimental data obtained from thermogravimetry.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1451-1456
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• 2017

Finding technical issues associated with equipment scale-up is an important subject for the investigation of pyroprocessing. In this respect, electrolytic reduction of 1 kg $UO_2$, a unit process of pyroprocessing, was conducted using graphite as an anode material to figure out the scale-up issues of the C anode-based system at pilot scale. The graphite anode can transfer a current that is 6-7 times higher than that of a conventional Pt anode with the same reactor, showing the superiority of the graphite anode. $UO_2$ pellets were turned into metallic U during the reaction. However, several problems were discovered after the experiments, such as reaction instability by reduced effective anode area (induced by the existence of $Cl_2$ around anode and anode consumption), relatively low metal conversion rate, and corrosion of the reactor. These issues should be overcome for the scale-up of the electrolytic reducer using the C anode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.917-920
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• 2001

Effects of addition of manganese and final reduction on segregation behavior of sulfur and final mangetic induction during final annealing have been investigated in the 300 ppm sulfur-contained 3% silicon-iron alloy strips with or without manganese. At the same concentration of sulfur, lower final reduction is favorable for final Goss texture. This is because the probability that the initial Goss grains survive under the highly segregated sulfur atmosphere and grow selectively within the segregated sulfur-free time range becomes higher. In the case of 3% silicon-iron with manganese, much lower magnetic induction was obtained, although the weak final reduction of 30% is given to the alloy, comparative to the 40%. This is because MnS particles acted as an reducer in the primary grain size.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.83-87
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• 2008

EPS(Electric Power Steering) system, which has replaced the hydraulic steering system(HPS or HPAS) in many passenger cars recently, have many merits such as low energy consumption, easy mounting, light weight and improvement of environmental pollution. However, EPS system has the problem of motor noise when motor is rotated, which can make a driver feel uncomfortable. There are many techniques to solve those problems, but they are not clear. It is necessary to evaluate the mechanical noise in steering systems, because an EPS has vibration sources such as at the motor gear reducer, manual gears and intermediate joints. In this paper, reduction technique of EPS motor noise is introduced.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.51.2-51.2
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• 2014

CQUEAN(Camera for QUasars in EArly uNiverse) has been used at the 2.1 m Otto Struve Telescope of the McDonald Observatory since 2010. This camera is optimized at 0.7 - 1.1 um for the survey of Lyman break of high redshift (z > 5) quasars in the early universe. The current system has a filter wheel consist of seven (g', r', I', z', Y, Iz and Is) broad-band filters. We are upgrading this filter wheel to have 20 narrow band filters, with which we can take spectral energy distributions of targets. The new filter wheel consists of interchangeable cartridges for 50 mm square filters, a speed reducer unit, and a step motor. This new design of the large size filter wheel can be applied to other large format CCD cameras.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.67-72
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• 2011

Recently, photovoltaic generator system is widely extended by energy policy of the government. Add to this, for high efficiency of power generation per natural light unit area is needed to sun tracking system. And it is needed to condensed light generator for reducer of equipment expense. As method of solving this problem, this paper is developed multi-flat reflector sun tracking system for sun photocell maximum power generation. The system is consisted of multi-flat reflector and two axes machinery and sun location perceiver and AVR controller. GaAs 3J cell generated 6.75 times power more than silicon cell by times condensing light system. As a result, condensing light system of multi-flat reflector generated maximum power and showed reducing costs to photovoltaic generator.

• Solar Energy
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• v.19 no.4
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• pp.81-91
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• 1999

The work presented here is a design and development of sun tracking system for the parabolic dish concentrator. Parabolic dish concentrator is mounted on azimuth and elevation tracking mechanism, and controlled to track the sun with computed and measured sun positions. Sun tracking mechanism is composed of 1/30000 speed reducer(3 stages) and 400W AC servomotor for each axis. The nominal tracking speed of each axis is ${\pm}0.6^{\circ}/sec$ and the system has a driving range of $340^{\circ}$ in azimuth and of $135^{\circ}$ in elevation. Sun tracking control system consists of sun sensor, wind speed and direction measurement system, AC servomotor position control system and personal computer as a master controller. Sun sensor detects the sun located within ${\pm}50^{\circ}$ measured from the sun sensor normal direction. Computer computes the sun position, sunrise and sunset times and controls the orientation of parabolic dish concentrator through the AC servomotor position control system. It also makes a decision of whether the system should follow the sun or not based on the information collected from sun sensor and wind speed and direction measurement system. The sun tracking system developed in this work is implemented for the experimental work and shows a good sun tracking performance.