• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.72-80
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• 2000

This study aims at the optimal design of the screw rotor, its performance analysis, and development of a small screw supercharger which has a low noise compared with the root type supercharger. The basic theoretical equations and the basic design of the screw supercharger have been established. The optical design of the screw rotor's shape has been also performed theoretically. Also, the performance analysis technique of the designed screw rotor has been developed.

• Journal of KSNVE
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• v.5 no.2
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• pp.257-264
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• 1995

We designed the cutter profile for symmetric screw rotor and did vibration experiment of screw rotor manufactured by the designed cutter profile. The results of this study are summarized as follows. (1) We designed the cutter profile of screw rotor (4-6)(5-6) by using numerical analysis program. (2) The maximum amplitude and variation of amplitude of 5-6 profile rotor are about 30 - 36.7% and 10 - 25% smaller than those of 4-6 profile rotor, respectively. (3) As the angular velocity of rotor changes from 100 to 300 rpm, the vibration of X, Y axis in driving shaft of 5-6 profile rotor is about 10 - 20% smaller than that of 4-6 profile rotor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.45-52
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• 1997

In this study, we designed tooth profile of the fly-cutter for antisymmetric rotor which is used in screw compressor. In order to verify this profile, we manufactured three different pairs(J46, N46, P46) of antisymmetric rotor using fly-cutter. We got the following conclusions from this study. (1) We obtained better contact condition using 3pairs of rotor which are manufactured by the fly-cutter. (2) We could prevent the cutter interference near bottom point of the robe of screw rotor.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.2
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• pp.184-193
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• 2002

This study aims at the optimal design of the screw rotor and its performance analysis. The optimal design of the screw rotor's shape has been performed theoretically. Also, the performance analysis technique of an oil-injected screw air compressor is developed. The effect of internal leakage, heat exchange between air and oil, and flow resistance at suction and discharge ports are included in the performance analysis. Some numerical examples of the volumetric efficiency and adiabatic efficiency for sample rotors are demonstrated for various lobe combination, rotor wrap angles and L/D ratios.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1285-1288
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• 2005

Screw rotors, the key parts of screw compressors, are used in compressing air and refrigerant due to their high productivity, compact size, low noise and maintenance. In general, a screw compressor is composed of a pair of rotors of complex geometric shape. The manufacturing cost of the screw rotors is high because the complicated helical shapes of the screw rotors are manufactured usually by the dedicated machine tools. In this study, rotor profile is divided into three parts for the efficient machining. The formed tools are designed and shared for the respective split region. By cutting the screw rotor using the formed tools, this method is more efficient than the end mill in machining rotor. Experimental results show that 4-axis machining using formed tools needs less time and has the accuracy.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.7 no.2
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• pp.243-247
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• 2004

Rotor's syndrome is a hereditary disorder characterized by predominantly conjugated hyperbilirubinemia with normal hepatic histology. It resembles Dubin-Johnson syndrome but the main differences are no dark brown pigmentation in the hepatic cells and visualization of the gallbladder in oral cholangiography. We experienced a 14 year-old male patient who had icteric sclerae and predominantly conjugated hyperbilirubinemia when he was hospitalized for varicocelectomy. His liver biopsy specimen showed no dark brown pigmentation and any other pathologic abnormalities in the hepatic cells. Hepatobiliary scan shows no evidence of obstructive lesions. His urinary excretion of total coproporphyrin was markedly increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.195-201
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• 1998

This study aims at the optimal design of rotors and the development of screw type Supercharger of CNG-fueled engine for commercial vehicle. Based on the new rotor profile, an advanced oil free type Supercharger has been developed, which can achieve higher adiabatic efficiency and lower manufacturing cost. The performance test of screw type Supercharger has achieved high volumetric efficiency and the durability on the bench of performance test has also been established in the compact body.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.668-671
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• 2001

For the saving of energy consumption, it is necessary that the high efficient energy transfer machine. We found the optimum operating condition of screw water chiller during this performance test. The specifications of compressor for this performance test are as follows. Built-in volume ratio; Vi=2.4, using refrigerant; HCFC-22, nominal motor output; 60kW(80Hp). We found the test results on water cooled chiller standard test condition that the evaporating capacity is increased 8% maximum and 5.6% under same operating condition. and COP is increased 11 % max. and 8% under same operating condition with change of the evaporating inlet/outlet condition. For the results of these test, we can estimate the optimum operating condition of water cooled type screw chiller.

• Polymer(Korea)
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• v.39 no.3
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• pp.441-452
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• 2015

Twin-screw kneader is an efficient polymer processing equipment. In this paper, the mixing performance of one novel intermeshing counter-rotating twin-screw kneader with different tip angles of the male rotor is simulated using the mesh superimposition technique (MST). Statistical analysis is carried out for the flow field using particle tracking technique, and distributive mixing performance is evaluated using the residence time distribution and segregation scale, while the dispersive mixing performance is estimated using the parameters such as shear rate, stretching rate and mixing index. The results show that the best distributive mixing performance is achieved when the tip angle is 0o, while the optimal dispersive mixing performance is obtained when the tip angle is 20o. The results in this paper provide a data basis for the selection of parameters and optimization of the performance for the screw rotors.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.139-142
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• 1999

Screw rotors are core parts of screw type air compressors, compressors in refrigerating machines and super chargers of automobiles etc. They are composed of a female and a male rotors which have complex section profiles and helically swept geometry. Screw type compressors have advantages of low noise, high efficiency, less needs in maintenance etc. Usually, machining process of screw rotors requires long machining time using CNC machine designed only for screw rotors, which increase the cost of production. In this work, the screw rotors for air-compressors were manufactured with fiber reinforced epoxy composite materials by resin transfer molding process. The mold for the RTM process was made of aluminum and silicon rubber and was designed for release of helical shape products. Composite screw rotors, manufactured by RTM process, have advantages of lightweight, less cost of production, good characteristics of vibration etc.