• Proceedings of the Korean Magnestics Society Conference
• /
• 2009.12a
• /
• pp.217-219
• /
• 2009

A GMI magnetic field sensor working based on time-coded principle has been investigated and designed. The laboratory model has been constructed and tested carefully, demonstrating the sensitivity of $3\;{\mu}s/{\mu}T$ in the field range of ${\pm}100\;{\mu}T$. An amorphous thin wire, $100\;{\mu}m$ in diameter ${\times}50\;mm$ in length, was chosen to be sensing element which was fit into a small field modulation coil of 60 mm in length. The sensor is working based on a time-coded principle that, with the magnetic field modulation was chosen in range of hundreds of Hz, the change in time interval of two adjacent GMI peaks relating to external DC magnetic field is proportional to the intensity of the external field to be measured. This mechanism has made a great improvement to the linearity of the sensor.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.11a
• /
• pp.235-239
• /
• 2008

Cable systems are a construction of elements carrying only tension and no compression or bending in membrane structure. Tensile membrane structures are most often used as roofs as they can economically and attractively span large distances. But cable systems have weaknesses to vibration by earthquake, wind and vehicle loads. Damage detection of cable systems by using existing safety diagnosis is difficult to detect the characteristic change of overall structural action. If cable snaps are occurred to cable release and tear in tension structures, these are set up a vibration. So, we used piezo-electric materials, and The principle of operation of a piezoelectric sensor is that a physical dimension, transformed into a force, acts on two opposing faces of the sensing element. In this study, the development on test method of cable system is proposed and tested by tensile strength using piezo-electric materials.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.4 no.4
• /
• pp.34-38
• /
• 2005

This is a widespread requirement for low cost lightweight thermal imaging sensors for both military and civilian applications. Today, a large number of uncooled infrared detector developments are under progress due to the availability of silicon technology that enables realization of low cost IR sensor. System prices are continuing to drop, and swelling production volume will soon drive process substantially lower. The feasibility of micromechanical optical and infrared (IR) detection using microcantilevers is demonstrated. Microcantilevers provide a simple Structurefor developing single- and multi-element sensors for visible and infrared radiation that are smaller, more sensitive and lower in cost than quantum or thermal detectors. Microcantilevers coated with a heat absorbing layer undergo bending due to the differential stress originating from the bimetallic effect. This paper reports a micromachined silicon uncooled thermal imager intended for applications in automated process control. This paper presents the design, fabrication, and the behavior of cantilever for thermomechanical sensing.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.04a
• /
• pp.89-94
• /
• 2001

A cylindrical capacitance-type spindle displacement sensor was designed and tested in the hard turning as a way to develop a sensor that can estimate cutting forces without using a tool dynamometer. The displacement sensor was installed between the face of spindle cover and the chucking element, and measured pure radial motion of the spindle. Ceramic inserts and tool steel workpieceof 65 Rc were used during the hard turning tests. The signals from the sensor showed the same pattern of cutting force variations as those from the tool dynamometer. The research results showed that the developed sensor could be utilized as an effective and cheap on-line sensing device to estimate cutting forces.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2003.04a
• /
• pp.472-477
• /
• 2003

Spindle state monitoring is getting more and more important according to the technology trend of spindle that is accurate and automated. Spindle state monitoring is to measure the state of rotation vibrations. The spindle rotation error motion detected by sensing device includes rotation object's unbalance, external forced vibrations, shape error of spindle, as well as measuring error of monitoring device. In this paper, we have inspected the runout characteristics. Also, we introduce the way to exclude the runout element that appear while you monitor a spindle state.

• Journal of Power System Engineering
• /
• v.19 no.3
• /
• pp.5-10
• /
• 2015

Femtosecond laser machining has been applied for creating a sensor function in silica glass optical fibers. Femtosecond laser pulses make it possible to fabricate micro structures in processed regions of a very thin glass fiber line because femtosecond laser pulses can extremely minimize thermal effects. With the laser machining to optical fiber using a single shot of 210-fs laser at a wavelength of 800 nm, it was observed that a processed region surrounded a thin layer which seemed to be a hollow cavity monitored by scanning electron microscopy (SEM). This study aims at a theoretical investigation for the processed region by using a numerical analysis in order to embed sensing function to optical fibers. Numerical methods based finite element method (FEM) has been used for an optical waveguide modeling. This report suggests two types modeling and describes a comparative study on optical losses obtained by the experiment and the numerical analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11a
• /
• pp.465-470
• /
• 2001

Two-phase BLDC(brushless DC) motor has larger torque ripple than three-phase BLDC motor because of its unique skeleton-type structure. An electronic switching mechanism to change the current-direction of the BLDC motor can be a source of vibration as well as unbalanced rotor weight. A proper switching timing which makes less vibrations was considered by changing the position of sensing element around the center of rotation. Also, the current of the motor was measured for the calculation of the motor efficiency. From the vibration test results and with the consideration of the motor efficiency, an optimal switching position of the Hall sensor was found.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1627-1632
• /
• 2000

Recently, piezoelectric materials have attracted considerable attention because of its self-sensing and actuating properties. To model smart structures, numerical modeling of structures with piezoelectric devices is essential. As many factors affect the performance of smart structures, optimization of these parameters is necessary. In this paper, the shape design sensitivity analysis of the 3D piezoelectric and structural elements is developed and shape optimization is performed. For the evaluation of the sensitivity, the finite element method is used. For the shape sensitivity, the domain velocity field is calculated. An acoustic cavity model is presented as a numerical example to study the feasibility of the formulation. The continuum sensitivity is compared with the results of the finite difference method by ANSYS. And the sequential linear programming (SLP) algorithm is used as the optimization algorithm.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.1
• /
• pp.25-29
• /
• 2017

This paper presents a unique pressure sensor design for environmental applications. The design uses a new geometry for a multi bossed beam-membrane structure with a SOI (silicon-on-insulator) substrate and a mechanical transducer. The Intellisuite MEMS CAD design tool was used to build and analyze the structure with FEM (finite element modeling). The working principle of the multi bossed beam structure is explained. FEM calculations show that a sensing diaphragm with Mises stress can provide superior linear response compared to a stress-free diaphragm. These simulation results are validated by comparing the estimated deflection response. The results show that, the sensitivity is enhanced by using both the novel geometry and the SOI substrate.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.67 no.2
• /
• pp.100-105
• /
• 2018

In this paper, we determined the driver's stress and fatigue level through physiological signals of a driver in the connected car environment, accordingly designing and implementing the architecture of the connected cars' platforms needed to provide services to make the driving environments comfortable and reduce the driver's fatigue level. It includes a gateway between AVN and ECU for the vehicle control, a framework for native applications and web applications based on AVN, and a sensing device and an emotion estimation engine for application services. This paper will provide the element technologies for the connected car-based convergence services and their implementation methods, and reference models for the service design.