• Journal of the Korean Ceramic Society
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• v.31 no.10
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• pp.1099-1106
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• 1994

It is suggested that the microstructural toughening process in the initial rising portion of R-curves observed in polycrystalline alumina should be different from the grain bridging mechanism identified in the long crack regime. Microcracking in the advancing crack front seems to be a prerequisite for the development of unbroken bridging ligaments behind the crack tip. In order to test such a proposition, attempts were made to identify experimentally the presence of microcracks in the frontal zone of propagating cracks. In-situ observation is made of crack growth in a miniature double cantilever beam specimen of a average grain size of 10 ${\mu}{\textrm}{m}$ alumina. Presence of a few microcracks was identified in front of crack tip on the propagating crack plane. The R-curves were re-evaluated based on the observation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.378.2-378
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• 2002

This paper deals with a moving coil type linear motor for fast access of the miniature ODD. This slim-line motor is composed of the mover supported by guide mechanism, the coil wound into it, and the yoke attached to the permanent magnet for stator. The driving force is generated by the PM of the stator and the current in the coil of the mover. Magnetic circuit analysis and Finite Element Method are applied to estimate force at air gap. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.274-279
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• 2000

Driving of the engine makes unbalance forces which induces vibration to the engine mount system. Active vibration control must be performed to reduce the vibration and the propagation of structure-born sound. In this study, the engine system is modeled as 3-dim. vibration system including flexible structures and an effective active noise control method is proposed. Also, appropriate actuator and sensor locations and types are selected. The miniature of the engine vibration system with multi-input multi-output is built and an active vibration control with multiple filtered-X LMS algorithm is applied to it. The applied control method was effective to reduce the transmitted vibration power through the rubber mount It showed the feasibility of the control of the engine vibration systems with flexible structures.

• Proceedings of the Korean Society of Veterinary Pathology Conference
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• 2003.10a
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• pp.9-9
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• 2003

Primary canine lung tumor is very uncommon and account for only about 1％ of all cancers diagnosed [1]. The average age at diagnosis is about 10 years and no breed or sex predilection has been confirmed. Almost all primary cancers of the lungs are carcinomas, the most common being adenocrcinoma. This study describes primary lung tumor in a dog that is accompanied by cerebellar metastasis with related neurologic signs. (omitted)

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.502-506
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• 1999

Recently, the miniature of electric products such as notebook, cellular-phone etc. is apparently appeared, due to the smaller size of the semiconductor chips. As the size of chip gets smaller, the circuit could be easily damaged by the slightest influence, so it is important to control the chipping generation in the process of dicing. This paper deals with chipping of the silicon wafer dicing. The relationships between the dicing force and the wafer chipping are investigated. It is confirmed that the wafer chipping increases as the dicing force increases.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.28-32
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• 2002

Recently, the miniature of electric products such as notebook, cellular-phone etc. is apparently appeared, due to the smaller size of the semiconductor chips. As the size of chip gets smaller, the circuit could be easily damaged by the slightest influence, therefore it is important to investigate the machining quality of $\mu$ BGA. This paper deals with machining characteristics of the $\mu$ BGA singulation. The relationships between the singulation face and machining quality of the $\mu$ BGA singulation are investigated. It is confirmed that machining quality improves as the singulation force decreases.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.6
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• pp.859-866
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• 2010

Generally, a fixed type guide-bush system is installed during machining miniature work-pieces with high precision in the multi-task CNC lathe. But a conventional guide-bush system does not provide a constant clamping force under the condition of varying work-piece diameters. It is important to maintain a constant clamping force for guaranteeing machining precision. This paper proposes a new guide-bush system with a pneumatic clamping device for the CNC Swiss-turn lathe to keep constant clamping force with changes in work-piece diameters. Through performance tests, new clamping system developed in the study showed better machining precision at the cost of a small increase in the temperature of the system than conventional systems due to an increase in the frictional heat and a change in the heat transfer route.

• The Journal of Korea Robotics Society
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• v.3 no.1
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• pp.16-22
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• 2008

Recently, automatic parking assist systems are commercially available in some cars. In order to improve the reliability and the accuracy of parking control, pose uncertainty of a vehicle and some experimental issues should be solved. In this paper, following three schemes are proposed. (1) Odometry calibration scheme for the Car-Like Mobile Robot.(CLMR) (2) Accurate localization using Extended Kalman Filter(EKF) based redundant odometry fusion. (3) Trajectory tracking controller to compensate the tracking error of the CLMR. The proposed schemes are experimentally verified using a miniature Car-Like Mobile Robot. This paper shows that odometry accuracy and trajectory tracking performance can be dramatically improved by using the proposed schemes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1043-1047
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• 2003

Most of the measurement and the evaluation of hand-transmitted vibration have been performed by using a small size single axis accelerometer between the handle and the hand palm or a three axis accelerometer attached on an adapter outside the hand(indirect measurement). It is most desirable for the correct evaluation of hand-transmitted vibration form the power tool handle to measure the acceleration between the handle surface and the hand palm in the three axis(direct measurement) as recommended in ISO 5349-1. In the study three axes acceleration measurement device was developed of which the thickness was less than 7mm so that it can be placed between the handle and the palm without any inconvenience during the measurement. To verify the performance of the developed device, measured acceleration by the two methods, direct and indirect, were compared in the study.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.9 s.252
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• pp.913-920
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• 2006

Three-dimensional flow and aerodynamic loss in the tip-leakage flow region of a high-turning first-stage turbine rotor blade with a squealer tip have been measured with a straight miniature five-hole probe for the tip gap-to-chord ratio, h/c, of 2.0%. This squealer tip has a indent-to-chord ratio, $h/{st}/c$, of 5.5%. The results are compared with those for a plane tip $(h_{st}/c=0.0%)$. The squealer tip tends to reduce the mass flow through the tip gap and to suppress the development of the tip-leakage vortex. Therefore, it delivers lower aerodynamic loss in the near-tip region than the plane tip does. At the mid-span, however, the aerodynamic loss has nearly the same value for the two different tips.