• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2004.04a
• /
• pp.453-458
• /
• 2004

A capacitate sensor is a proper device for measuring high small displacement. General design parameters and procedure are discussed and a test sensor was built to have a measuring range of 100$\mu\textrm{m}$ and a sensitivity about 30nm. This sensor has too opposing electrode of comparably large area and has nominal gap distance about 150$\mu\textrm{m}$. So as to achieve a nano order displacement sensitivity, both sensor and target system have to be considered. This is important for the sensitivity can be achieved by minimizing a system total noise level in electronic type sensor application. Typical performance of the developed sensor is demonstrated in precision moving stage having 0.1$\mu\textrm{m}$ moving resolution.

• Journal of the Korean Society of Industry Convergence
• /
• v.17 no.3
• /
• pp.113-121
• /
• 2014

This paper presents a optimization design of 10[W] single phase BLDC motor applied Notch shape. Cogging Torque causes noise, vibration and torque ripple so notched stator is proposed in this paper. Firstly, a single phase BLDC motor needs applying aymmetric air-gap shape because this type motor cannot help having dead-point which is zero torque position. However, using asymmetric air-gap structure causes cogging torque increase. Therefore, this paper proposes the notch shape structure. Notch shape structure has some advantages; low cost, easy to apply. There are 4 optimal factors selected in optimization process, which are position and size of notches. Through building a prototype, the result of FE analysis and the experimental measurement value are compared each other and then vailidity and utility of simulation will be verified.

• Journal of the Korean Institute of Educational Facilities
• /
• v.12 no.6
• /
• pp.18-25
• /
• 2005

The purpose of this study is to investigate cognitive gap between users and architectural experts for architectural planning of elementary schools to support effective decision-makings. For this study, each architectural factor was selected from the journals published by Korean Institute of Education Facilities(KIEF) from 2000 to 2004. Among these factors, the priority planning factors were decided through Analytic Hierarchy Process(AHP). The results of this study showed users' emphasis on the amenities of physical environment such as orientation, ventilation, noise, view, but experts' preference on spatial composition of space and function such as orientation, circulation, zoning, parking lot, courtyard. This difference shows clear cognitive gaps between two groups and also suggests factors required to be considered to develop effective decision-making in elementary school planning.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.9
• /
• pp.493-498
• /
• 2002

Double-side linear pulse motor(DSLPM) has more advantages than single-side linear pulse motor because noise and vibration can be considerably decreased by countervailing the normal forces, which is generated between two stators and mover. However, DSLPM has more complicated magnetic flux path and layout of stator pole toot/mover tooth rather than single-side linear pulse motor In this paper, DSLPM is designed and fabricated by considering the air gap magnetic density, shape of tooth and slot. In order to verify the characteristics of DSLPM, the air gap magnetic flux density is analyzed by 2D FEM and the magnetic flux path is analyzed by 3D FEM. Also the static thrust forces is obtained with the analyzed results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.873-876
• /
• 2002

It has been reported that discrepancies exist in the case of double panels with an air layer when the measured sound transmission loss is compared with the calculated values. It has been known that the cause of this discrepancy is in major from the unavoidable dips associated with the double wall resonances. In this work, several correction methods to make up for such resonances are studied. In particular, the ‘boundary damping’concept is revisited and its effects are discussed by comparing with measured values. It is shown that the correction methods are necessary for the sound insulation analysis of double partitions with an air layer, in order to ascertain the quantitative correlation between measured and predicted values.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.10a
• /
• pp.467-471
• /
• 2009

In this study a cantilevered carbon nanotube(CNT) switch was investigated with the linear and the nonlinear structural models incorporating the electrostatic force and van der Waals interactions between the CNT and ground surface. Due to the applied voltage and van der Waals interactions the CNT deforms statically and dynamically and finally pull into the surface. When the nonlinear model is considered in case of the relatively large gap between the CNT and the surface, the static pull-in voltage was increased due to the nonlinear hardening effect. Also the dynamic response was investigated with the different external dc and ac voltages. The CNT shows various dynamic behaviors and instabilities including dynamic pull-in. Based on this study, further research on the dynamic and nonlinear stability of CNT nanodevices should be requested to develop the new type of nano switches or nano-memory.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.4
• /
• pp.287-293
• /
• 2002

The unexpected failure of the induction motor makes the downtime of production, and the cost of the process cessation enormous. To reduce the downtime and increase the reliability of the motor, the vibration measurements for the fault detection have been used previously. Recently motor current signature analysis(MCSA) has been adapted for the fault detection and diagnosis of the motors. MCSA provides a powerful analysis tool for detecting the presence of mechanical and electrical faults in both the motor and driven equipment. In this paper, the fault severity of the rotor bar has been derived in terms of the resistance change which is calculated from the equivalent circuit model. Results show that the fault of the rotor can be easily detected and the measured value of the resistance change is verified by the detected fault from on-site tests using MCSA for the induction motors in an iron foundry.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.887-887
• /
• 2004

The areal density of the hard disk drive(HDD) has been increased due to technological advances recently. To achieve the high areal density magnetic recording requires an extremely small gap between the air-bearing surface (ABS) and disk. At the same time, the slider mass and size should be reduced to minimize the physical contact under the operational and environmental conditions. Almost all of 2.5＂HDD companies will get ready for adoption of FEMTO slider and already utilized the small slider. FEMTO and small size slider will be mainstream in the 2.5" and other small form factor HDD in the near future. In this study, the flying characteristic of FEMTO slider was examined. Based on the simulation, FEMTO slider is very stable in flying dynamic under the disk modulation, however the flying height sensitivity of the manufacturing tolerances is much bigger than PICO slider. And the other characteristics like impulse response and load/unload dynamic were also examined in this study.tudy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.527-532
• /
• 2011

Whirling vibration in severe cases may result in shaft cracking and typically gap sensors are utilized to confirm its values under the outside underwater of ship. The bending stress value causing whirling vibration on the propulsion shafting system of a 40-ton small vessel was verified by theoretical analysis and its vibration measurement. However, because of underwater condition, the accuracy for this measurement method is presumed low. In this study, the strain gauge basic principle and the bending stress calculation method are considered. The relationships are then applied for obtaining the whirling vibration of the 40-ton small vessel. As a result, a new method in estimation of whirling vibration is reached and suggested.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.11 no.9
• /
• pp.439-453
• /
• 2001

This study deals with the free vibration of two identical circular plates coupled with a bounded fluid. An analytical method based on the finite Fourier-Bessel series expansion and Rayleigh-Ritz method is suggested. In the theory, it is assumed that the ideal fluid in a rigid cylindrical container and the two plates are clamped along the plate edges. The proposed method is verified by the finite element analysis using commercial program with a good accuracy. Two transverse vibration modes, namely in-phase and out-of-phase, are observed alternately in the fluid-coupled system when the number of nodal circles increases for the fixed nodal diameter. The effect of gap between the plates on the fluid-coupled natural frequencies sis also investigated.