• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.7-13
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• 2006

Linear compressors with a free piston driven by a linear motor are widely attention in the cooling apparatus such as refrigerator due to the high efficiency The stroke of piston in the linear compressor driven by LPMSM (Linear Permanent-Magnet Synchronous Motor) can be obtained from Integrating the input voltage and current of LPMSM, but it may be diverged due to dc components in the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and do offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The accurate stroke of a piston can be calculated by compensating for dc offset. The performance of the newly developed stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.22-30
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• 2010

KARI had integrated and tested GEO satellite in cooperation with Astrium Inc., France. In the middle of integration and test, It was necessary to check GEO satellite SA(solar array) status and require electrical interface verification with bus. SA of GEO satellite have different mechanical characteristics in comparison with those of LEO satellite which was tested in KARI. LEO SA has been deployed by simple mechanical hinge system but GEO SA has been done by more complicated method. so in this paper, we designed the test configuration and analyzed the test result of solar array electrical integration of GEO satellite.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.71-80
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• 2002

According to the rapid growth of high speed and precise industry, the application of synchronous motor has been increased. In the application fields, these fast dynamic response is of prime importance. In particular, since the PMLSM(Permanent Magnet Linear Synchronous Motor) has characteristics of high speed, high thrust, it has been used in high-performance servo drive. From these reasons, it is recently used for high precise position control, and machine tool. In this paper, a study of the sliding mode with VSS (Variable Structure System) design for a PMLSM is presented. For fast and precise motion control of PMLSM, the compensation of disturbance and parameter variation is necessary. Hence we eliminate the reaching phase use of VSS that is changed to switching function and vector control using the state observer. And we proposed to sliding mode control algorithm so that realize fast response without overshoot, disturbance and parameter variation.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.534-542
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• 2003

Small electric motors in an automobile perform various tasks such as engine cooling, pumping, HVAC etc. At present, most of them are DC motors supplied by 12V or 24V batteries. However, DC motors suffer from low efficiency, life cycles and reliability. Therefore, there is a growing interest in substituting DC motors for advanced at motors including switched reluctance motors(SRM). Although there are several other forms SRM convertors, they are either unsatisfactory to the control performance or unsuitable for the 12V battery source. Especially, a conventional asymmetric converter of SRM provides the best flexible and effective control to the current waveform of SRM, but it has the most switches and produces conducting voltage drops across two power switches during SRM operation. For automotive applications with a 12V battery source, this circuit is inadequate. For considering the requirement for effective operation and simple structure of converter in the limited internal circumstance of automobiles, the author inclines toward selecting Modified C-dump converter and Energy efficient c-dump converter.

• Journal of Biomedical Engineering Research
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• v.43 no.1
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• pp.27-34
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• 2022

Drunk driving defines a driver as unable to drive a vehicle safely due to drinking. To crack down on drunk driving, alcohol concentration evaluates through breathing and crack down on drinking using S-shaped courses. A method for assessing drunk driving without using BAC or BrAC is measurement via biosignal. Depending on the individual specificity of drinking, alcohol evaluation studies through various biosignals need to be conducted. In this study, we measure biosignals that are related to alcohol concentration, predict BrAC through SVM, and verify the effectiveness of the S-shaped course. Participants were 8 men who have a driving license. Subjects conducted a d2 test and a scenario evaluation of driving an S-shaped course when they attained BrAC's certain criteria. We utilized SVR to predict BrAC via biosignals. Statistical analysis used a one-way Anova test. Depending on the amount of drinking, there was a tendency to increase pupil size, HR, normLF, skin conductivity, body temperature, SE, and speed, while normHF tended to decrease. There was no apparent change in the respiratory rate and TN-E. The result of the D2 test tended to increase from 0.03% and decrease from 0.08%. Measured biosignals have enabled BrAC predictions using SVR models to obtain high Figs in primary and secondary cross-validations. In this study, we were able to predict BrAC through changes in biosignals and SVMs depending on alcohol concentration and verified the effectiveness of the S-shaped course drinking control method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.170-177
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• 2020

This study examined the clamping force control method and the braking performance test results of an electromechanical brake (EMB) using braking test equipment. Most of the studies related to EMBs have been carried out in the automotive field, dealing mainly with the static test results for various control methods. On the other hand, this study performed a dynamic performance evaluation. The three-phase interior permanent magnet synchronous motor (IPMSM) was applied to drive the actuator of the EMB, and the analysis was verified by JMAG(Ver. 18.0), which is finite element method (FEM) software. The current control, speed control, and position control were used for clamping force control of the EMB, and the maximum torque per ampere (MTPA) control was applied to the current controller for efficient control. The EMB's emergency braking deceleration performance was tested in the same way as conventional pneumatic brake systems when the wheel of a train rotates at 110 km/h, 230 km/h, and 300 km/h. The emergency braking time, with the wheel stopped completely at the maximum rotational speed, was approximately 73 seconds. The similarity of the braking time and deceleration pattern was verified through a comparison with the performance test results of the pneumatic brake system applied to the next generation high-speed railway vehicle (HEMU-430X).

• Journal of Practical Engineering Education
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• v.10 no.1
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• pp.17-24
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• 2018

Through the design and production of works for the third semester as a major unit, It is proposed the process of satisfying the graduation standards with the design and production process of the drone which can be applied to various mobile environments. Using the shape of Ring Propeller, it is made to be able to play both the role of generating lift as a propeller and the role of a wheel that touches the ground through the surface of the rim. In addition, the Servo Motor is used to convert the drive shaft of the motor to the correct angle according to the command. Then, based on the idea, the 3D printing is implemented to confirm the result of the configuration, and the circuit for driving the propulsion is designed and manufactured. As a result, the conversion of the desired propulsion system during air navigation and operation failed due to the weight increase of the propellant. It is confirmed that the size of the thrust and the tolerance limit of the ring propeller are the errors. Through these processes, it has been recognized to have experience of creative thinking and cooperation through engineering approach and comprehensive design, and confirmed to satisfy the graduation criteria by writing an engineering paper on the result.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.289-290
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• 2002

Stainless steel ball bearings are used in the control element drive mechanism and driving mechanisms such as step motor and gear boxes for the integral nuclear reactor, SMART. The bearings operate in pressurized pure water (primary coolant) at high temperature and should be lubricated with only this water because it is impossible to supply greases or any additional lubricant since the whole nuclear rector system should be perfectly sealed and the coolant cannot contain ingredients for bearing lubrication. Temperature of water changes from room temperature to about 120 degree Celsius and pressure rises up to 15MPa in the nuclear reactor. It can be anticipated that the frictional characteristics of the ball bearings changes according to the operating conditions, however little data are available in the literature. It is found that friction coefficient of 440C stainless steel itself does not change sharply according to temperature variation from the former research, and the friction coefficient is about 0.45 at low speed range. In this research frictional characteristics of the assembled ball bearings are investigated. A special tribometer is used to simulate the axial loading and the bearing operating conditions, temperature and pressure in the driving mechanism in the nuclear reactor. Highly purified water is used as lubricant ‘ and the water is heated up to 120 degree Celsius and pressurized to 15MPa. Friction force is monitored by the torque transducer.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.3 no.1
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• pp.1-6
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• 2009

In this paper, when wheelchair user get into the vehicle, we have thorough grasp of the problems of loading wheelchair and give effect to suggest conceptual design in relation to develop manufactured goods. We choose 50 participants with disabilities who manual wheelchair or motor scooter users are able to drive own's vehicle, and the method practice in the direct survey. There are some limitations in this study especially in terms of the sampling population. The 88%(n=44) of the participant replied to the driver with disabilities need assistive devices for loading manual wheelchair. They prefer a system that robot arm brings the wheelchair out of the trunk to the driver's seat door.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.241-242
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• 2011

교통 약자 승객의 편의성 증대, 도심의 매연 감소 및 온실가스 저감 등 대중 교통 선진화를 위해 친환경 초저상 전기버스의 개발이 필요하다. 초저상 전기버스는 초저상 액슬 일체형 휠모터 구동시스템을 탑재한 형태로 구현이 가능하며, 초저상 액슬 일체형 휠모터 구동시스템은 구동 모터를 액슬 허브에 일체화 시킴으로써 기존 구동시스템 대비 무게 및 사이즈가 대폭 줄어들고, 동력 전달 매커니즘을 획기적으로 개선하여 효율 향상 및 차량 연비 개선이 가능하다. 특히 바퀴 중심과 액슬 출력 중심에 단차를 둠으로써 차량의 전방 바닥 뿐만 아니라 후방바닥을 평평하게 유지할 수 있어 실내 공간이 획기적으로 개선되어 교통 약자를 포함한 승객의 편의성을 향상시킬 수 있다. 또한, 액슬 일체형 휠모터 구동시스템은 각 휠의 분산 구동이 가능하므로 동특성 및 구동제어성이 뛰어나고, ESP(Electronic Stability Program), VDC(Vehicle Dynamic Control) 등과 연계하여 통합적인 지능형 시스템을 구현할 수 있다. 액슬 일체형 휠모터 구동시스템은 휠모터와 감속기 및 휠모터제어기 등으로 구성되며, 본 논문에서는 초저상 액슬 일체형 구동시스템용 120kW급 휠모터 및 휠모터제어기의 개발 및 다이나모 환경에서 T-N 특성 및 최대 출력 시험, 효율 시험을 통해 전기버스 등 대형 차량(Heavy Duty Vehicle)에 적용 가능한 전기동력시스템의 성능을 확인하였다.