• 한국자기학회:학술대회 개요집
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• 한국자기학회 2009년도 정기총회 및 동계학술연구발표회
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• pp.217-219
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• 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.

• 한국초전도ㆍ저온공학회논문지
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• 제7권4호
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• pp.14-19
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• 2005

A transient numerical simulation was conducted to have variation of temperature on an element of resistive Superconducting Fault Current Limiter (SFCL) under quench condition. It is very important engineering information for an optimum design of cryogenic system for cooling of a resistive SFCL element. A bifilar coil for resistive SFCL for 10 MVA system was incorporated as a model in this numerical study. From the numerical simulation result, it was found that the averaged temperature on the shunt and Bi-2212 element at 500 kW, 100 ms was 711.1 K and 198.4 K respectively. The temperature variation with the change of the hot-spot size and time is also obtained. The maximum temperature was continuously increased in all cases until the hot-spot stops at 100ms and it was going down after then. Such as, the details of temperature distribution on the SFCL element obtained from this numerical study and it should be very valuable information on the decision of the cooling capacity of cryogenic system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.82-84
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• 1993

A method for simulating general characteristics and temperature characteristics of magnetizing fixture coil of the capacitor discharge impulse magnetizer-magnetizing fixture system using SPICE is presented. This method has been developed which can aid the design, understanding and inexpensive, time-saving of magnetizing circuit. As the detailed characteristics of magnetizing circuit can be obtained, the efficient design of the magnetizing circuit which produce desired magnet will be possible using our SPICE modeling. Especially, The knowledge of the temperature of the magnetizing fixture is very important to forecast the characteristics of the magnetizing circuits tinder different conditions. The capacitor voltage was not raised above 810[V] to protect the magnetizing fixture from excessive heating. The temperature estimation method uses multi-lumped model with equivalent thermal resistance and thermal capacitance.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.1-6
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• 1998

From surface flow visualization on a MIRA notchback reference model using oil flow technique, the topology of the singular points of the skin friction lines are delineated. Separation and reattachment lines at the front screen, at the A-pillar, at the C-pillar and on the rear side of the car including the trunk have been identified. It is worth to mention that two vortices emerging from the top of the trunk coil in the opposite direction as that vortices starting from the C-pillar edge. The positions of the singular points and the separation and reattachment lines and the foci of the vortices provide a sensitive database for validation of CFD-codes

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.98-102
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• 2009

The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. To manufacture the magneto-rheological fluid damper that uses such characteristics of the fluid, a flow analysis of the inner damper was conducted to forecast the damper's capacity. In addition, using the finite element method software, analysis on the characteristics of electromagnetic field around the coil operation unit inside the damper. Based on the result of the analysis, a single core damper and a double core damper were built and tested for their dynamic function. Based on the result of the experiment, the propriety of the flow analysis was demonstrated, and the proposed model was verified.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.664-669
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• 2003

This paper proposes a swing-arm type dual-stage actuator, which consists of a PZT actuator for fine motion and a VCM(Voice Coil Motor) for coarse motion, for SFF ODD(Small Form Factor Optical Disk Drive), in order to achieve fast access speed and precise track following control. We focus our attention on the design and control of the PZT actuator, because there have been a lot of previous researches related to the VCM and dual-stage actuators. Due to the dual cantilever structure, the PZT actuator can generate precise translational tracking motion at its tip where optical pickup is attached at, and the effect of hysteric behavior of the PZT element is reduced. The dynamic model of the PZT actuator is derived by using the Hamilton's principle, and verified by comparing with the experimental frequency response. The sliding mode control is designed in order to be robust against modeling uncertainties. Simulations and experimental results confirm the effectiveness of the suggested control scheme.

• 대한기계학회논문집B
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• 제26권5호
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• pp.716-723
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• 2002

Heat transfer in linear motor driven stages for surface mounting device applications was investigated. A simple one-dimensional thermal resistance model (TRM) was introduced. In order to reduce three-dimensional nature to one-dimensional, a few assumptions and simplifications were employed suitably. A good agreement with a finite element heat transfer analysis in temperature profile was obtained. For validation, the analysis was compared with the measurement with respect to motor driving power. Overall discrepancy was less than 7$^{\circ}C$. The influence of two high thermal resistance parts, insulation sheet and thermal contact between the coil assembly and the mounting plate, was examined through the analysis. Additionally, the thermal resistance analysis was applied to another stage including an internal cooling-air passage, and was found available for this system as well. After validation, the cooling effect was surveyed in terms of motor power, and cooling-air and -water flow rate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.96-101
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• 2001

Heat transfer in linear motor driven stages for surface mounting device applications was investigated. A simple one-dimensional thermal resistance model was introduced. In order to reduce three-dimensional nature to one-dimensional, a few assumptions and simplifications were employed suitably. A good agreement with a finite element heat transfer analysis in temperature profile was obtained. For validation, the analysis was compared with the measurement with respect to motor driving power. Overall discrepancy was less than $7^{\circ}C$. The influence of two high thermal resistance parts, insulation sheet and thermal contact between the coil assembly and the mounting plate, was examined through the analysis. Additionally, the thermal resistance analysis was applied to another stage including an internal cooling-air passage, and was found available for this system as well. After validation, the cooling effect was surveyed in terms of motor power, and cooling-air flow rate.

• 한국정밀공학회지
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• 제21권10호
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• pp.170-179
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• 2004

A vibration model of powder transfer equipment is developed by the lumped parameter method. A Powder transfer equipment does surging motion, bouncing motion and pitching motion. Motion equation becomes decoupling and removed vibration exciting source about pitching motion, and therefore designers presented the optimum design plan to be able to do adjustment with motion trajectory of powder transfer equipment. That is, way for design to be able to do motion trajectory of powder transfer equipment through change of design element as installation position and direction of motor, driving speed, mass unbalance, stiffness coefficient and installation position of support coil spring is presented. The design results, powder transfer equipment were able to know that fatigue destruction does not occur, and the reason is because maximum stress working on a basket structure is more very than fatigue strength small.

• 한국정밀공학회지
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• 제24권8호통권197호
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• pp.89-96
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• 2007

In this paper, a new air bearing stage with magnetic preload and a linear motor has been developed for the small precision machine systems. The new air bearing stage is unique in the sense that permanent magnets attached bottom of the iron core of table are used not only for preloading air bearings in vertical direction but also for generating thrust force by current of the coil at base. The characteristics of air bearings using porous pads were analyzed with numerical method, and the magnetic circuit model was derived for linear motor for calculating required preload force and thrust force. A prototype of single axis miniature stage with size of $120(W){\times}120(L){\times}50(H)\;mm^3$ was designed and fabricated and examined its performances, vertical stiffness, load capacity, thrust force and positioning resolution.