• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.92-97
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• 1994

The there axis CNC grinding machine tool for ultra-precison mirror surface grinding of advanced materials such as ceramics and other hard and brittle materials was designed and manufactured. The grinding machine is composed of the air spindle, the high damping resin concrete bed, and the three axis CNC controller with the high resolution AC servo motor. To investigate the dynamic properties of the grinding machine, the natural frequencies of the spindle and the headstock were experimentally measured. The truing method using the break truer to revise the shape of the metal bonded diamond wheel was developed. Form the results of the machining using the prototype three axis CNC grinding machine manufactured, the mirror surface were achieved.

• 한국정밀공학회지
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• 제28권4호
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• pp.422-426
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• 2011

The spindle system is very important unit for the product accuracy in machine tools. A spindle system is designed by using the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The static and dynamic analysis and stiffness evaluation of 45,000rpm spindle for machine tool has been investigated. Using a finite element method, we obtained some analyzed a static and dynamic characteristics of a spindle, such as natural frequency, harmonic analysis and we got the value of compliance through it. We evaluated stiffness by taking the inverse this value. A 45,000rpm spindle is successfully developed using the results.

• Journal of Trauma and Injury
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• 제26권4호
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• pp.319-322
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• 2013

A 66 year-old woman had cervical spinal cord injury by an automobile. We performed emergency operation for partial quadriplegia. She recovered from motor weakness gradually, but complained of abdominal distension and mild dyspnea. A physical examination of her abdomen did not have tenderness and rebound tenderness. She underwent a decubitus view of chest X-ray due to aggravated dyspnea at postoperative 4 days. We detected free air gas of abdomen and immediately identified a cause of pneumoperitoneum by abdominal computed tomography. We performed an emergent laparotomy and confirmed a jejunal perforation. After an operation, she recovered well and is under rehabilitation.

• KSTLE International Journal
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• 제4권1호
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• pp.8-13
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• 2003

Abrasion in fretting wear mechanism is studied experimentally with the specimens of two different shapes of spacer grid spring and fuel tubes of a nuclear fuel. Reciprocating sliding wear test has been carried out in the environment of air and water at room temperature. Especially, third body abrasion is referred to for explaining the wear region expansion found during the slip displacement increase with constant normal contact farce. It is found that the expansion behaviour depends on the contact shape. The small clearance between the tube and spring seems to be the preferable region of the wear particle accumulation, which causes third body abrasion of the non-contact area. Even in water environment the third body abrasion occurs apparently. Since the abrasion on the clearance contributes wear volume, the influence of the contact shape on the severity of third body abrasion should be considered to improve the grid spring design in the point of restraining wear damage of a nuclear fuel.

• 한국자동차공학회논문집
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• 제12권5호
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• pp.180-186
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• 2004

The simulator of a vehicle equipped with mechanical transmission and hydraulic accumulator type-braking energy regeneration system is developed using a PC. The simulator receives the shift lever position, the accelerator pedal angle and the brake pedal angle generated by the operator using the keyboard, updates the state variables of the energy regeneration system responding to the input signals, and draws the moving pictures of the accumulator piston and pump/motor plate angle every drawing time on the PC monitor. Also, the operator can observe the shift lever position, the accel pedal angle, brake pedal angle, pressures of accumulators, vehicle speed, hydraulic torque, engine torque and air brake torque representing the operation of braking energy regeneration system through the PC monitor every drawing time. The simulator can be a very useful tool to design and improve the braking energy regeneration system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권7호
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• pp.320-326
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• 2003

Slotless Permanent Magnet Linear Synchronous Motor (PMLSM) has good control ability but thrust density is low. So, this paper proposes inserted core type of slotless PMLSM to improve its thrust density. Inserting the core between windings of each phase, detent force is generated by the difference of magnetic resistance in an air gap. To minimize detent force, this paper applies the neural network to inserted core type of slotless PMLSM. The, Magnetic pole ratio, the width of the inserted core and the width of the coil are selected as a design parameter to minimize detent force. In comparison with inserted core type one, thrust ripple greatly decreases by minimizing detent force and also thrust increases in this optimal model.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.55-58
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• 2003

IPMSM (Interior Permanent Magnet Synchronous Motor) is widely used in many applications such as an electric vehicle, compressor drives of air conditioner and machine tool spindle drives. In order to maximize the efficiency in such applications, this paper is proposed the optimal control method of the armature current. The controllable electrical loss which consists of the copper loss and the iron loss can be minimized by the optimal control of the armature current. The minimization of loss is possible to realize efficiency optimization control for the proposed IPMSM The proposed control algorithm is applied to IPMSM drive system, the operating characteristics controlled by efficiency optimization control are examined in detail by simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.785-786
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• 2006

Performance comparison of IPMSMs with distributed and concentrated winding is presented in this papcr. Two IPMSMs have been designed and fabricated with identical rotor dimension, air-gap length, series turn number, stator outer radius, and axial length except winding configuration. Basic parameters and machine performance, such as resistances, back emf, output torque, and efficiency, are compared. From the comparison results, motor design considering winding configuration is discussed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.43-45
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• 1994

This paper proposes the new method to calculate the static thrust and normal force of a hybrid type double-sided linear pulse motor by the coenergy which considered the magnetic nonlinealities. In the process of the computation, the nonlinear characteristics of the magnetic material were interpolated by the cubic spline method. And, to investigate the characteristics of the hybrid type DLPM, the static thrust and the normal force is shown as a function of displacement, input current and air airgap length. Also the simulation values are compared with the experimental ones obtained from a hybrid type DLPM.

• 한국정밀공학회지
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• 제31권6호
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• pp.491-495
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• 2014

We developed a compact high-precision slot-die coating machine for thin-film deposition on a flexible substrate. For smooth and precise coating, air-bearing and linear motor system were employed to minimize velocity ripple. The gap control mechanism is specially designed to have repeatability of gap between nozzle and substrate under 1 ${\mu}m$. Due to extremely precise gap control, the machine can coat thin-films down to 50 nm with $200mm{\times}100mm$ size. A thin film of Ag nano-particle ink is coated for demonstration.