• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.2
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• pp.57-65
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• 2008

The atomization phenomena and spray characteristics of drum type rotary atomizer using centrifugal force from high rotational speed of gas turbine engine shaft were studied through rotary atomizer modeling analysis and experimental method. A test rig for rotary atomization that has range of $5,000{\sim}40,000\;rpm$ was used to make similarity for high speed rotating shaft. Spray visualization methodology and Phase Doppler Anemometry were also used to investigate the atomization mechanism and spray characteristics. We found that the rotating fuel spray has unique breakup process and we have to make breakup point earlier through increasing rotating speed to improve atomization performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.672-675
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• 2006

It is becoming more significant to develop a rotary VCM type actuator for small form factor ODD, as portables are getting more and more popularized nowadays. In this paper, the procedure of development of the actuator which is applicable to compact flash II card and is fit in the specification of BD 1X is explained. This is based on the rotary VCM type actuator, which is good for reducing thickness. Air core solenoid coil is used in order to do focusing mechanism. And the total weight is reduced by using the structure of steel-aluminium-steel triple layer, so, the stiffness is still adequate. Additionally, the tracking coil is moved next to the actuator, so the total length was reduced, then the actuator become applicable to compact flash II card. The force of Magnetic Circuit is improved by using Magnetic Circuit DOE. And flexible mode frequency improved through the DOE of structure part. Modeling was exactly done in consideration of air core solenoid coil and pivot bearing. It is confirmed that the designed model is satisfied with the specification of BD 1X and is applicable to Compact Flash II card.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.127-134
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• 2017

A rotary table is a positioning device used in metalworking for the multiple axes of machine tools, and the utilization trend is increasing with machining efficiency. In the construction of a rotary table, the core technology is a power transfer unit that drives the table, typically a gear type and a roller gear cam type. As the rollers installed on the turret column have rolling movement on the contact surface of the roller gear cam, the roller gear cam type has the advantage of low wear, high load, and fast driving. Therefore, it is currently being replaced by a roller gear cam type. In this study, we researched a 5-axis machining method for the roller gear cam on a rotary table and a new method of applying double roller gear cam curve to reduce the noise and shock between the roller and the cam surface. We implemented the 5-axis machining process in this study using software to generate NC-code and machined the roller gear cams using a Mazak Integrex-200IV. We found that the roller gear cam and turret were able to identify mutual touch status and the noise from the operation of the roller gear cam was substantially reduced.

• Journal of Biosystems Engineering
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• v.30 no.3 s.110
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• pp.135-140
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• 2005

Vegetable transplanting operation has been wholly depended on human labor that needs 18.4 hrs per 10 acres in Korea. Since periods of vegetable transplanting operations are limited, their mechanization has been strongly demanded. This study was conducted to develop a transplanting device that was the core technology for vegetable transplanter. In order to find out transplanting track and velocity of transplanting device, a kinematic analysis software was employed. Evaluation of prototype was carried out in the circular soil bin with high speed camera. Rotary type transplanting device produced an elliptic loci when two links of different lengths were moving to the opposite direction. The length of two links was 75mm and 44mm, respectively. Maximum displacement of rotary type transplanting device was 238mm. It seemed that the transplanting elliptic loci of transplanting device were identical between the simulation output generated by kinematic analysis software and the circular soil bin test result with a high speed camera. The rotary type transplanting device can be suitable fur transplanting short height vegetable, less than 20 cm length vegetables such as Chinese cabbage and cabbage, etc.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.107-115
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• 2014

Highly functional mill turrets have been developed and continuously improved to shorten the manufacturing time and enable multiple uses. Among these, a mill turret with B-axis rotary table was developed. The B-axis rotary table should be evaluated for structural integrity. Moreover, its worm and worm gear for transmitting power should be able to endure fatigue damage. Therefore, this article presents a structural analysis of this type of B-axis rotary table and confirms its static stability by comparing the stress results to the allowable stress levels. Next, the dynamic stability of the rotary table was investigated via a mode analysis and a harmonic analysis in a range determined by the results of a modal analysis. Finally, a worm gear set, the main part that drives the rotary table, is analyzed for fatigue and to estimate its lifetime. The results of the fatigue analysis allowed a prediction of the life of the worm gear set. The analytical results show that the B-axis rotary table has good structural integrity.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.8
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• pp.687-692
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• 2015

LAM (Laser-Assisted Machining) is an effective method for processing difficult-to-cut workpieces. The focal length of a LAM system is changed by the change of the workpiece shape during laser preheating; this problem is solved by changing the lens of the laser module. Linear- and rotary-type lens changers were developed to change the laser lens of a LAM system. The linear-type lens changer is operated by a motor with a ball-screw, and the rotary type is operated by a stepping motor. The natural frequency and structural stability of the laser lens changers were confirmed by using a finite element analysis; in addition, the functions of the lens changers were verified by measuring the iterative accuracy. The measured results show that the rotary-type lens changer is more accurate than the linear-type changer.

• The KSFM Journal of Fluid Machinery
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• v.8 no.2 s.29
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• pp.23-30
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• 2005

The rotary compressor is widely used in the air conditioner because it is efficient and compact. Recently, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce the noise level and to improve the efficiency. The new type muffler that has two side discharge holes and dome shape resulted in much lower overall noise level, especially noise levels around 1kHz than the old type one of one center discharge hole in the acoustic spectra. Also it showed a higher efficiency of air conditioner by lowering oil discharging amount of a compressor than old type one of a rectangular shape and two side discharge holes. The noise reduction and efficiency improvement by the new type muffler were verified by tests for votary compressors and air conditioners.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2242-2249
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• 2006

The rolling piston type rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. The present analysis is part of a research program directed toward maximizing the advantages of refrigerant compressors. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressors. Therefore, theoretical investigation of the lubrication characteristics of a rotary compressor being used for refrigeration and air-conditioning systems was investigated. The Newton-Raphson method was used for a partial elastohydrodynamic lubrication analysis between the vane and the rolling piston of a rotary compressor. The results demonstrated that the vane thickness and the center line position of the vane significantly influenced the friction force and the energy loss between the vane and the rolling piston.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.562-568
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• 2001

The rolling piston type-rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. The present analysis is part of a research program directed toward maximizing the advantages of refrigerant compressors. The study of lubrication characteristics in critical sliding components is essential for the design of refrigerant compressors. Therefore, theoretical investigation of the lubrication characteristics of a rotary compressor used for refrigeration and air-conditioning systems was studied. The Newton-Raphson method was used for the partial elastohydrodynamic lubrication analysis between the vane and the rolling piston of a rotary compressor. The results showed that the rotational speed of a shaft and the discharge pressure significantly influence the friction force and the energy loss between the vane and the rolling piston.

• Tribology and Lubricants
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• v.17 no.2
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• pp.138-145
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• 2001

The rolling piston type rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. The present analysis is a part of research program directed toward maximizing these advantages of refrigerant compressors. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressors. Therefore, theoretical investigation of the lubrication characteristics of a rotary compressor used for refrigeration and air-conditioning systems is studied. Newton-Raphson method is used for the partial elastohydrodynamic lubrication analysis between vane and rolling piston in the rotary compressor. The results show that the rotational speed of a shaft and the discharge pressure influence significantly the friction force and the energy loss between vane and rolling piston.