• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.215-223
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• 2016

In this study, a novel rotor position sensorless estimation method of an interior permanent-magnet synchronous motor is proposed. A square-wave pulsating voltage signal is injected in the estimated synchronous reference frame. This signal is interpreted in the stationary reference frame regardless of the estimated rotor position. Thus, assuming that the position error is nearly zero is unnecessary because the variables in the estimated synchronous reference frame are not used. The rotor position can be exactly calculated from two voltage references and three sampled current feedbacks in the stationary reference frame. The proposed method is easy to implement and helps enhance the bandwidth of the current controller. The validity of the proposed method is verified by simulations and experiments.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.131-136
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• 2001

The purpose of this paper is to develop image inspection system endows an automatic operating and measuring that the moment values are invariant with respect to variable object size and rotation. In this paper, using these moment feature vector with Hu s 7 invariant moment is also given. The characteristics of section which is applied in the mechanics used moment descriptor of invariant moment detection algorithm for image inspection system. Corresponding rates between 94% and 96% have been achived for all object tested.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.1
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• pp.38-44
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• 2002

In manufacturing die and mold, polishing: is important as it takes as much as 50% of the production cost. In this research, an attachable type polishing device to a WC machining center was developed. experiments were done with a special1y designed rotation type polishing device. Also an ultra-sonic (vibration type) waving device was introduced to acquire finer surface finishes. From the constructed data base based on the experimental results, it is shown that optimal polishing conditions are generated by the combined use of the rotation type tool and the vibration type tool.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.164-169
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• 2003

The purpose of this study is to develop a practical image inspect ion system that could recognize it correctly, endowing flexibility to the productive field, although the same object for work will be changed in the size and rotated. In this experiment, it selected a fighter, rotating the direction from 30$^{\circ}$ to 45 simultaneously while changing the size from 1/4 to 1/16, as an object inspection without using another hardware for exclusive image processing. The invariant moments, Hu has suggested, was used as feature vector moment descriptor. As a result of the experiment, the image inspect ion system developed from this research was operated in real-time regardless of the chance of size and rotation for the object inspection, and it maintained the correspondent rates steadily above from 94％ to 96％. Accordingly, it is considered as the flexibility can be considerably endowed to the factory automat ion when the image inspect ion system developed from this research is applied to the product ive field.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.473-477
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• 2000

The experimental study of die-sinking electrical discharge machining(EDM) was conducted for Cold Die Alloy Steel of SKD-11 with rotary electrode according to the peak current of 11A, 15A and 19A, and the duty factor of 0.24, 0.45. dielectric fluid flow through the electrode inside according to the change of electrode internal diameter during the EDM working. Material removal rate(MRR) was increased with flushing & rotation of electrode at the condition for the peak current of 15A, 19a but the MRR is decreased at the flushing only. The more surface roughness was obtained for the case of the flushing & rotation under the peak current of 19A.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.457-462
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• 2004

Active magnetic bearings (AMB's) have become practical in many industrial fields and numbers of studies for magnetic bearing systems have been reported. However, AMB systems are open-loop unstable and thus require feedback control for robust stabilization and performance. In this paper, first, a rotation of the rotor around the inertial axis is considered and a rigorous modeling of a magnetic bearing system in which the rotation of the rotor is on its axis of inertia is developed. Next, to stabilize the AMB system a PID controller is used and experimentally analyze its rotational response.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.151-158
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• 2001

This paper presents a method for evaluating the lubrication characteristics between the plunger and cylinder in a radial type plunger pump. A numerical analysis is carried out in order to obtain the pressure distribution and acting forces between the plunger and cylinder. The pressure distribution is also measured experimentally by using pressure transducer through the cam type test machine. The experimental pressure distribution result is compared with the numerical result which is estimated by the computer simulation. In conclusion, the acting forces to the plunger are expressed for the operating conditions such as clearance, supply pressure, rotation speed and viscosity of oil.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.3
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• pp.36-44
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• 2013

This study is focused on the debarking and xylem separation yield of Paper Mulberry. We investigated the most efficient manual on the automatic debarking and xylem separator machine. The bast tissues of Paper Mulberry were separated in three layers including black outer layer, green inner layer, and white inner layer. A target is to save the white inner layer of these three layers as much as possible. The experimental machine most characterize xylem separation and debarking by frictional force between the bulges and Paper Mulberry by the drum rotation. It is possible automatically to operate the machine by controlling the temperature sensor and the time. Debarking process can be know that removed black outer layer has beem accumulate and measured the weight. The content of the extract, holocellulose, lignin and ashes of the white inner layer was analyzed. It is result that conditions of optimum process of the experimental machine is 45 RPM, temperature at $60^{\circ}C$(60 min.) and $80^{\circ}C$(60 min.), mixing bulge of 10 mm(120ea) and 30 mm(120ea) and capacity of Paper Mulberry 10 kg.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.660-665
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• 2002

Mirror surface finish of Si-wafers has been achieved by rotary in-feed machining with cup-type wheels in ELID grinding. But the diameter of the workpiece is limited with the diameter of grinding wheel in the in-feed machining method. In this study, grinding experiments by the rotary surface grinding machine with straight type wheels ware conducted, by which the possible grinding area of the workpiece is independent of the diameter of the wheels. For the purpose of investigating the grinding characteristics of large scale diametrical silicon wafer, grinding conditions such as rotation speed of grinding wheels and revolution of workpieces are varied, and grinding machine used in this experiment is rotary type surface grinding n/c equipment with an ELID wit. The surface ground using the SD8000 wheels showed that mirror like surface roughness can be attained near 2 - 6 nm in Ra.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.2
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• pp.121-126
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• 2013

Precision machine tools for high dignity cutting are needed for efforts to improve machining accuracy. However, there are many factors to improve machining accuracy. This study investigated how machining accuracy changes when variation and unbalance amount in rotational speed domain is decreased. Machining accuracy of initial machine tools depends on manufacturing and assembly of parts such as bearing. And then, vibration and noise vary with volume of unbalance amount when it is rotation, so it effects unbalance amount. Also vibration and noise increased by unbalance shorten spindle's life and it especially makes worse boring accuracy. Therefore, this study studied the change of roundness and cylindricity of workpiece when it decreases variation and unbalance in rotational speed domain.