• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.349-354
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• 2011

Tuned mass damper is widely used in many applications of industry. The main advantage of tuned mass damper is that it can increase the damping ratio of system and reduce the vibration amplitude. Meanwhile, the natural frequency of system will be divided by two peaks, and the peak speeds are closely related to the mass and the stiffness of auxiliary mass system added. In addition, the damping ratio will also affect the peak frequency of the dynamic response. In the present research, the nonlinear mechanical characteristics of rubber is investigated and put into use, since it is usually manufactured as the spring element of tuned mass damper. By the sense of the nonlinear stiffness as well as the damping ratio which can be changed by preload applied on, the shape memory alloy is proposed to control the auxiliary mass system by self-optimizing. Supported by the experiment data of rubber, the 1 DOF theoretical model and finite element model based on computer simulation are implemented to perform the feasibility of the proposed semi-active tuned mass damper working on the drive shaft.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.7-14
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• 2014

Inverter module, which feeds the converted power to the traction motor for EMU. Consists of the power semiconductors with their gate drive unit(GDU)s and the control computer for driving, voltage, current and speed controls. Electrolytic condenser, connected to the gate drive unit and a core component to drive the power semiconductor, has problems such as reduction in lifetime and malfunction caused by electrical and mechanical characteristic changes from heat generation during high speed switching for generation of stable power. In this study, To check the service life of electrolytic condenser, the test was carried out in two ways. First, In the case of accelerated life testing of condenser, the Arrhenius model is a way of life testing. Another way is to analyze the reliability of the failure data by the method of parametric data analysis. Eventually, life time by accelerated life test than a method of failure data analysis(Weibull distribution) was found to be slightly larger output.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.5
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• pp.552-558
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• 2016

A control rod drive mechanism(CRDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod within a reactor core to control the reactivity of the core. The CRDM for Jordan Research and Training Reactor with 5MW power has been designed and fabricated based on the HANARO’s experience through KAERI and DAEWOO consortium. This paper describes the seismic test results to demonstrate the operability, the drop performance and the structural integrity of CRDM during or after seismic excitations. The seismic tests are carried out under 5 OBE and 1 SSE loads at three Test Rigs simulating the reactor structure and the pool top. From the tests, the CRDM is smoothly driven without a malfunction of stepping motor under OBE load. The pure drop time under OBE and SSE loads is measured as 1.169s and 1.855s to meet the design requirement. Also, it is found that the CRDM maintains the structural integrity without a change of the function and natural frequency before and after seismic loads.

• Journal of Drive and Control
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• v.20 no.1
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• pp.34-40
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• 2023

The agricultural tractor ROPS test method according to OECD code 4 is a test to assess whether the driver's safety area can be secured when a tractor overturns, and reliability should be ensured. In this study, a model formula and procedure for calculating measurement uncertainty expressing reliability in the field of agricultural machinery testing were established according to the ISO/IEC Guide 98-3:2008. The characteristics of the ROPS test device were assessed and repeated tests were performed, and the were used as factors to calculate the measurement uncertainty. As a result of repeated tests, the accuracy was higher than 1.9 % in all load directions; thus, they were, applied to calculate the type A standard uncertainty. The final expanded uncertainty was calculated within the range of less than ± 7.76 kN of force and ± 6.96 mm of deformation in all load directions.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.177-177
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• 2018

• Journal of Power Electronics
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• v.5 no.1
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• pp.45-54
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• 2005

This paper presents an application of SR drives for LSEV's(Low Speed Electric Vehicles) which are used for golf and leisure. Two types of 5[HP] SRM's and its drive system are designed and tested. In order to be energy saving and have effective braking during deceleration, a multi-level inverter is proposed. For the precise switching angle control, a new type of analog encoder is proposed. A current control is adopted for soft starting and an angle control is adopted at high speed to increase efficiency. Drive characteristics and performance are shown with test results.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.468-473
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• 2004

The magnetic jack type Control Element Drive Mechanism (CEDM) had been developed and verified through electromechanical testing including the testing of the magnetic force required to lift the control element assembly. It would become inefficient in view of cost and time for parametric studies to be performed by test to improve the CEDM system. So it becomes necessary to develop a computational model to simulate the electromagnetic characteristics of the CEDM in order to improve the CEDM design efficiently. In this paper it is presented that the electromagnetic analysis using a 2D axisymmetric FEM model has been carried out to simulate the operation of the latch magnet of the CEDM to generate a current trace for latch coil. The results show the calculated current trace is very similar to the real current trace taken from the CEDM.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.52-60
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• 2005

This paper deals with the position control fur a feed drive system in CNC milling machine, which utilizes a modified error signal for the elimination of steady-state error. A linear time-invariant (LTI) system has consistent properties in response to standard test signal inputs. Those also appear in an error curve acquired from the response. From such properties, constructed is an error model for the position control of the feed drive. And then added is the output of the error model to the current error signal. Consequently the resulting proportional control system brings performance improvement in view of the steady-state error. The effectiveness of the proposed scheme is confirmed through simulations and experiments.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.219-225
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• 1999

Monitoring of the cutting force signals in cutting process has been well emphasized in machine tool communities. Although the cutting force can be directly measured by a tool dynamometer, this method is not always feasible because of high cost and limitations in setup. In this paper an indirect cutting force monitoring system is developed so that the cutting force in turning process is estimated based on a AC spindle drive model. This monitoring system considers the cutting force as a disturbance input to the spindle drive and estimates the cutting force based on the inverse dynamic model. The inverse dynamic model represents the dynamic relation between the cutting force, the motor torque and the motor power. The proposed monitoring system is realized on a CNC lathe and its estimation performance is evaluated experimentally.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.450-454
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• 1994

From a point of view in energy saving and improvement of productivity, inverter for large power induction motor drive is very important. In this thesis, we developed high voltage inverter for large power induction motor drive. We experimented the inverter with R-L series load, successfully, and are going to do the field test in the real plant.