• Journal of Korean Society of Water and Wastewater
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• v.13 no.3
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• pp.107-115
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• 1999

The general objectives of this study are to develop a new biofilm reactor equipped with agitating mixer and to evaluated the treatment efficiency of the reactor. The experimental tests were conducted to estimate the oxygen transfer rate of agitating mixer system. Results are as follows. 1. The oxygen transfer coefficient, KLa, was $8.94hr{-1}$ and $7.50hr{-1}$ at 500rpm and 250rpm of agitating mixer speed, respectively. When the agitating mixer was used in the biofilm reactor, 22.5% and 18.8% of oxygen transfer rates were increased at 500rpm and 250rpm, respectively. 2. The removal rate of BOD and CODcr was decreased by 5.0% when the agitating mixer speed was varied from low (250rpm) to high level (500rpm). 3. The concentration of attached biomass had a difference of 5.0% to 7.3%, whereas that of suspended biomass had a difference of about 15.0%, depending upon variation of the agitating mixer speed.

• Journal of Drive and Control
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• v.14 no.1
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• pp.1-7
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• 2017

The power train of a concrete truck mixer reducer includes differential planetary gears to get a large reduction ratio for operating the mixer drum in a compact structure. These differential planetary gears are a very important part of the mixer reducer where strength problems are the main concern. Gear bending stress, gear compressive stress and scoring failure are the main concerns. Many failures in differential planetary gears are due to the insufficient gear strength and resonance problems caused by major excitation forces such as gear mating failure in the transmission. In the present study, where the excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate differential planetary gear critical speeds. Mode shapes and natural frequencies of the differential planetary gears are calculated by CATIA V5. These are used to predict gear resonance failures by comparing the working speed range with the critical speeds due to the gear transmission errors of the differential planetary gears.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1529-1534
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• 2008

Recently, mixers are being widely used in the display and semiconductor company in order to mix the chemical materials. The mixer normally consists of shaft, hub, reduction gear, and driving motor. It is one of the key design factors to evaluate the dynamic characteristics caused by the rotation. In this study, the dynamic characteristics of the high speed mixer, such as vibration, noise and thermal radiation, are verified by the experiment. Through the experiment, it is shown that the structural unbalance mass of high speed mixer is the important source of the severe vibrations and maximum temperature is mixer bowl.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.445-452
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• 2001

Generally, OPC(ordinary portland cement) is used for grouting in Korea, and bentonite has usually been added to prevent the deposition of cement particles. The dispersion of CB(cement bentonite) grout is influenced by variable factors i.e. water to cement ratio, particle size of cement, kind of bentonite, adding volume, methods of adding, viscosity of CB grout materials and curdling time. Among variable factors, the viscosity of CB grout materials is influenced by the dispersion, and dispersion is improved as increasing the mixing speed. In this paper, described a suitable mixing speed of the High Speed Mixer in field, engineering characteristics of CB grout materials vary with the water to cement ratio and the mixing speed as well as confirming the state of dispersion.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.410-416
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• 2021

To improve the capacity and stability of natural graphite, the electrochemical performances were investigated by using the prepared natural graphite coated with petroleum pitch for anode materials. The pitch coated natural graphite was prepared using a dry speed mixer by adjusting the rotation speed of the mixer, time, composition of graphite and softening point of the pitch. The physical properties of the anode material were analyzed using SEM, TEM, and PSD. The electrochemical performances were investigated by cycle, C-rate, EIS and CV test. When the pitch coated natural graphite was tested in the condition of 9000 RPM, 10 wt%, 2 h, and softening point of 150 ℃, it showed the highest capacity of 324.5 mAh/g at 0.1 C and a capacity retention rate of 98.9% after 50 cycles. In the test for evaluating rate performance, the capacity retention rate (5 C/0.1 C) was 80.3% and was improved by about 1.7 times over the pristine natural graphite.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.5
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• pp.544-551
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• 2013

Recently high speed mixer, which is mixing, grinding, dispersion for liquid-liquid material, has been widely used several industries such as food, cosmetics, pharmaceuticals, fine chemicals, electronic material. This high speed mixer has a core element part called particle separation device. Particle separation device, which makes mixed liquid and liquid material using shear forces from a rotor and a stator, is a decisive factor in the distributed parts. In this study, we examined the velocity distribution of the two models of particle separation device using computation fluid dynamics, so that we were able to see the difference of the velocity distribution according to the shape. Also, by experiment, we observed that the use of rotor-screen type is deemed more suitable in case of accurately considering the effect of improving of the dispersibility through the circulation of the future.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.16-20
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• 2002

This paper describes the resistive FET mixer with low IF for the 4-Ch DBF(Digital Beam Forming) receiver with LNA(Low Noise Amplifier). This DBF receiver based on the direct conversion method is generally suitable for high-speed wireless mobile communications. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(IF) considered in this research are 2.09 ㎓, 2.08 ㎓ and 10㎒, respectively. The RF input power, LO input power and Vgs are used -10㏈m, 6㏈m and -0.4 V, respectively. In the 4-Ch resistive FET mixer with LNA, the measured IF and harmonic components of 10㎒, 20㎒, 2.09㎓ and 4.17㎓ are about -12.5 ㏈m, -57㏈m, -40㏈m and -54㏈m, respectively. The IF output power observed at each channel of 10㎒ is about -12.5㏈m and it is higher 27.5 ㏈m than the maximum harmonic component of 2.09㎓. Each IF output spectrum of the 4-Ch is observed almost same value and it shows a good agreement with the prediction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1307-1312
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• 2005

Turbulent in-situ mixing process is a new material process technology to get dispersed phase in nanometer size by controlling reaction of liquid/liquid, liquid/solid and liquid/gas, flow and solidification speed simultaneously. In this study mixing, the key technology to this synthesis method will be studied by computational fluid dynamics. For the simulation of mixing of liquid metal, static mixers will be investigated. Two inlets for different liquid metal meet and merge like 'Y' shape tube. The tube has various shapes such as straight and curved. Also, the radius of curve will be varied. The performance of mixer will be evaluated with quantitative analysis with coefficient of variance of mass fraction. Also, detailed plots of intersection will be presented to understand effect of mixer shape on mixing.

• Journal of the Semiconductor & Display Technology
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• v.12 no.3
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• pp.1-6
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• 2013

In many technical fields including electronics and display manufacturing processes, properties of coating liquids could be greatly enhanced by adding nanopowders and it requires efficient mixing techniques to achieve uniform dispersion of nanoparticles in liquids. This paper presents the three-dimensional CFD simulations on the flowfields of a highly viscous liquid in the large scale industrial mixer of impeller type. The effects of several important design and operation parameters such as impeller geometry, rotational speed, and degree of liquid viscosity are investigated to appreciate the mixing performance by examining the computational results for flow pattern of rotationally stirred liquid of high viscosity in the mixer.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.549-552
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• 2006

Generally the ultra-high strength steel reinforced concrete has rich mix composition composed of high-strength type mineral admixtures and as a result of very low water-binder ratio(about under w/b=25%), it reveals ultra-high compressive strength(about over 100Mpa). Also, in order to obtain sufficient toughness after construction, we usually mix a large quantity steel fiber with ultra-high strength steel reinforced concrete therefore we must use proper mixer for workability. When we make the ultra-high strength steel reinforced concrete we need more long mixing time or much super-plasticizer than when we manufacture normal concrete. These bring about economical problems and performance deterioration. Therefore, in this study, in order to manufacture easily ultra-high strength steel reinforced concrete we develope a dedicated mixer for ultra-high strength steel reinforced concrete with high speed type. It carried out the examination for comparison between the dedicated and general type mixer, the analysis and counterplan of the point at issue when we manufacture ultra-high strength steel reinforced concrete by the dedicated mixer.