• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.253-261
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• 2014

In this paper, vibration analysis of power differential gear train for 2.5MW wind turbine system is analyzed. which system is composed of two planetary gear set, one helical gear set and main shaft that connected by flange. Planetary gear set, helical gear set, main shaft are modeled in MASTA program and housing, torque arm, carrier, flange components are modeling by finite element method. Each models are combined by component mode superposition. To analysis of natural vibration characteristic about 2.5MW wind turbine gear train was performed and check about critical speed with wind load, mass unbalance, angle misalignment excitation frequency.

• Journal of Biosystems Engineering
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• v.41 no.3
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• pp.177-183
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• 2016

Purpose: Mee (Madhuca longifolia) is an economically important tree growing throughout Sri Lanka. Its importance is mainly attributed to its oil with high nutritional and medicinal values. However, an inefficient extraction method limits its use. This study revealed the possibility of extracting oil from mee seeds by using a screw-type oil expeller. Methods: A popular screw-type oil expeller was used in the experiment. Extract bar clearance and speeds of the main spiral shaft were altered to increase the oil expelling efficiency of the machine. The quality of refined oil at the optimum oil yield was determined by measuring the refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity. Results: An optimum yield of 35% oil was obtained when the machine capacity was 30 kg/h and energy consumption was 0.13 kWh/kg. This optimum machine condition was observed at an extract bar clearance of 0.5 mm and a main spiral shaft speed of 90 rpm. The refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity of the oil were 1.4, 203, 59, 3.5%, 0.2%, and 0.907 g/cm3 respectively. Color of the mee oil was closer to yellow, which is revealed by the lightness value (L) of 24.93 and positive value (b) of 11.81. Conclusion: The screw-type oil expeller can be used for economically extracting mee oil on a commercial scale.

• Tribology and Lubricants
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• v.33 no.5
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• pp.214-219
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• 2017

Abrasive fluidized bed machining (AFBM) is similar to general abrasive fluidized machining (AFM) in that it can perform polishing of the outer and inner surfaces of a 3-dimensional shape by the flow of particles. However, in the case of AFM, the shear force generated by the flow of the particles causes material removal, while in AFBM, the abrasive particles are suspended in the chamber to form a bed. AFBM can be used for deburring, polishing, edge contouring, shot peening, and cleaning of mechanical parts. Most studies on AFBM are limited to metals, and research on application of AFBM to plastic materials has not been performed yet. Therefore, in this study, we investigate the effect of rotating speed of the specimen and the air flow rate on the material removal characteristics during AFBM of polyacetal with a horizontal AFBM machine. The material removal rate (MRR) increases linearly with increase of the rotating speed of the main shaft because of the shear force between the particles of the fluidized bed and the rotation of the workpiece. The reduction in surface roughness tends to increase as the rotating speed of the main shaft increases. As the air flow rate increases, the MRR tends to decrease. At a flow rate of 70 L/min or more, the MRR remains almost constant. The reduction of the surface roughness of the specimen is found to decrease with increasing air flow rate.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.125-127
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• 2002

This paper presents the measurement process of the rotational accuracy and the comparison with the theoretical results in the main bearing of scroll compressor. The main bearing is cylindrical oil proceeding bearing, but there are straightly cut used for oil supply. Therefore the roundness error is not a negligible quantity compared with the rotational accuracy. For this reason, three-point method is used in the experiment. The result of three-point method coincides with the theoretical value. So if the theory in this paper is used to the bearing design of scroll compressor, the efforts for testing and designing can be reduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.124-129
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• 2010

Wind load characteristics is investigated for vibration analysis of wind turbine gearbox. A normal wind model assumed, of which the wind velocity is increased according to the height from ground. A blast wind model is assumed, of which the maximum velocity is located at the center and the velocity profile is normally distributed. The periodical torque and bending moments transmitted to the main shaft of wind turbine are investigated. The average values and the harmonic terms of the transmitted moments are studied on the wind direction of range $-45^{\circ}{\sim}45^{\circ}$ and the bending moment characteristics are examined, which is regarded as the main source of the misalignment of gear train.

• International Journal of Fluid Machinery and Systems
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• v.4 no.4
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• pp.396-409
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• 2011

Water turbines have been used in electricity generation for well over a century. Hydroelectricity now supplies 19% of world electricity. Many hydro power plants are operated with Pelton turbines, which is an impulse turbine. The main reasons for using impulse turbines are that they are very simple and relatively cheap. As the stream flow varies, water flow to the turbine can be easily controlled by changing the number of nozzles or by using adjustable nozzles. Scientific investigation and design of turbines saw rapid advancement during last century. Most of the research that had been done on turbines were focused on improving the performance with particular reference to turbine components such as shaft seals, speed increasers and bearings. There is not much information available on effects of blade friction on the performance of turbine. The main focus in this paper is to analyze the performance of Pelton turbine particularly with respect to their blade friction.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.697-703
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• 2000

In design step of an active vibration control system, the stability analysis is required for obtaining a stable control region so that the system is protected from it violent natural vibration. This paper describes the procedure of stability simulation for the active magnetic bearing-main spindle of a machine tool. The characteristic equation of the overall system is derived by assembling the dynamic equation of a flexible shaft and the transfer functions of feedback components. And the stable region is obtained by calculating the eigenvalues of the characteristic equation. The simulated control stable region is good agreement by comparing the experiment. Therefore the stable control gain is selected in this paper.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.627-635
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• 2019

In this study, we developed for processing complex features using CAM software that satisfies precision for example practice and related qualification tests suiTable for CNC training purposes. In addition, functions such as location control, speed control, and processing path generation, which are the main functions of CNC machining machines, were constructed using small equipment parts, servo motors, inverters, general purpose PCs, and commercial NC software and researched with the goal of developing low-cost education equipment. In the static accuracy inspection, the degree of machine when measuring the parallelism of the X, Y and Z axes and the vibration of the main shaft did not reach the allowable value. However, we have obtained a finished product that satisfies the CNC machine book sample shape machining, detailed functions of the position control function of the CNC machine tool, linear interpolation function, circular interpolation function, and tool offset function. In the qualification test shape processing, a shape with a degree of 1/100 mm was processed to obtain position accuracy that satisfied the tolerance.

• Korean Institute of Interior Design Journal
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• v.24 no.6
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• pp.221-228
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• 2015

This study aims to define concepts on Hospital Design Focused on System to respond to the development and change by comparing general design methods of the General hospital architecture in Korea and analyze elements suitable to concepts on Hospital Design Focused on System in the General hospital architecture through examining the transformation of General hospitals in Korea. Essential architectural elements composing the Hospital Design Focused on System are as follows. First of all, the elements which can react to development of hospital architecture are HOSPITAL STREET and site situation. Secondly, core, equipment shaft, column, MAIN STREET and air handling unit room are elements of great importance as the location of these elements determines the dimensions and scale of the space which hospital functions are assigned to. Third, the area in regard to the rate of change is formed by MAIN STREET, which is the primary element, and envelope. The depth between MAIN STREET and envelope is defined as space depth. The flexible area is determined depending on this space depth and thus how to set up this flexible area determines the degree of readiness in responding to the change.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.2
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• pp.16-23
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• 2005

This study is intended to find out the reason of interference phenomenon of a machine tool when it operates for 5-axises working. The researcher made a Virtual Machine which has same figures of the 5 axises machine tool and Virtual Manufacturing System which has both Software factors - controller and NC code data to manipulate the movement characteristics of the machine - and Hardware factors - fixtures, workpiece, tools, holders and so on. With these virtual tools, this study is designed to find out the relation between the movement and the interference or collision, and also intended to verify the simulation and work-processing. In this study, the researcher found out, in case of the vertical 5 axises type, that it has more chances to have interference between the fixture, the workpiece and the main spindle including the tool holder due to the tilting kinetics of the main spindle. In case of the horizontal 5 axises type, on the other hand, the researcher found out that it has more possibility to have the interference between the main spindle and the rotary shaft.