• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.478-485
• /
• 2003

Today, although there have been high technical developments of a compressor in the respect of its capacity, it has been so hard to develop in the respect of vibration and noise because mechanical structure of it has originally numerous vibration and noise. However, if we can grasp the point of systematic phenomena of vibration and noise through the understanding of dynamic characteristics in mechanical equipment, it may be possible to consider countermeasures. In this study about a reciprocal compressor, the part of its machinery is modeled as rigid body, and the part of its spring is modeled as flexible body, and then they are analyzed by DADS. Each rigid body and spring are connected with joint torque of a motor is applied to shaft, and pressure is applied to a piston so that a compressor can be revolved. Based on this modeling, influence of a compressor's vibration is analyzed through changes of offset, connecting rod and crank radius In the case of weight balance, it I produced after re-design, and then changes of vibration of a compressor's inside are checked through experiments. These analysis data may help set measures of reducing vibration of a reciprocal compressor.

• Journal of the Korean Society of Industry Convergence
• /
• v.17 no.3
• /
• pp.84-92
• /
• 2014

In this paper, a novel 5-axis hybrid-kinematic machine tool is introduced and the research results on accuracy improvement of the prototype machine tool are presented. The 5-axis hybrid machine tool is made up of a 3-DOF parallel manipulator and a 2-DOF serial one connected in series. The machine tool maintains high ratio of stiffness to mass due to the parallel structure and high orientation capability due to the serial-type wrist. In order to acquire high accuracy, the methodology of measuring the output shafts by additional sensors instead of using encoder outputs at the motor shafts is proposed. In the kinematic view point, the hybrid manipulator reduces to a serial one, if the passive joints in the U-P serial chain at the center of the parallel manipulator are directly measured by additional sensors. Using the method of successive screw displacements, the kinematic error model is derived. Since a ball-bar is less expensive than a full position measurement device and sufficiently accurate for calibration, the kinematic calibration method of using a ball-bar is presented. The effectiveness of the calibration method has been verified through the simulations. Finally, the calibration experiment shows that the position accuracy of the prototype machine tool has been improved from 153 to $86{\mu}m$.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.18 no.4
• /
• pp.84-91
• /
• 2010

Owing to revolutionary developments in automobile technologies, a variety of advanced vehicles - hybrid vehicle, hydrogen fuel-cell vehicle, electric vehicle, etc. - emerges recently. The safety is getting more important for developing automobiles. The electro-magnetic compatibility has to be assured, since those advanced vehicles are equipped with various new electronic systems. Electro-magnetic compatibility tests, in general, consist of an EMI(electro-magnetic interference) test and an EMS (electro-magnetic susceptibility) test. We investigated the susceptibility test method suggested in KMVSS (Korean Motor Vehicle Safety Standard) as the EMS test method. A series of experiments results that the above test method should be partially revised to comply with a Korean governmental standard method. In this paper, the some directions of modifications are presented to enhance the quality of the above EMS test method.

• Proceedings of the KIEE Conference
• /
• 1994.07a
• /
• pp.39-42
• /
• 1994

The application of speed or position control technique in AC drives demands accurate position and velocity feedback information. Generally, resolver and absolute encoders are used as a velocity or position sensor. But they increase cost and when the sampling frequency is faster than sensoer's output frequency we can't Set exact information. In order to solve this problem this thesis proposes a speed and a position observer design for Permanent-Magnet Synchronous Motors(PMSM) specialty in low speed drives. Most literatures on this topic design the observer based on the field_oriented d_q model. But in this thesis, a new approach to machine dynamics is proposed. Since it is difficult to design the observer using the nonlinear model, the machine model is here linearlized at the operating point. The observer designed is implemented by software using Intel's 8097 microprocessor and verifies the proper performance of observer by simulation and experiment.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.546-551
• /
• 2004

An applying Thermodynamic method for the purpose of measuring hydraulic efficiency of pump-motor system, based on IEC60041 code, is not easy to adopt at field test. Even though there were splendid development in measuring technic in discharge measuring through the hydraulic machina lots of unsolved problems concerned in flow-rate are still remain in measuring hydraulic efficiency in hydraulic machine. The key point in measuring hydraulic efficiency is to measure exact flow-rate. So, Thermodynamic methode provides a good solution. This methode measures hydraulic efficiency by detecting the difference of temperature and pressure between the hydraulic process of machine, without measuring flow-rate of pump or turbine. By measuring temperature in mk level and absolute pressure in pascal, we can get a difference of thermodynamic specific energy in Moliere chart before and after of hydraulic process, md that difference is equal to hydraulic loses. Following the standard in proceeding Thermodynamic methode, I hope these trial and records make others be familiar to the thermal methode and make it easer to beginner for trial.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.21 no.47
• /
• pp.267-275
• /
• 1998

As social and economic environments rapidly change, all enterprises are struggling for the 21C. K company, a motor company, is building a new production system by one way of paradigm shift to get the competitive power in the market. This system includes concepts of the thinking shift from maker's view to consumers' view when it makes cars. Simultaneously, K company has been applying another new method 'Interchanges of Different Section of Industry' to make more competitive vendors since 1996. The old method, used until 1995, had worked well and gained lots of effects during the reform activities. But after the technical supervisors from K company had left almost everything went back to the starting point in the vendor company. The major causes of this phenomenon are that there were no ‘structure’ to maintain the reforming activities. We have confirmed that ‘Interchanges of Different Section of Industry’ is a good way to let this ‘structure’ exist continuously. After we compared and analyzed merits or demerits of this system through the experience of applying it to a vendor C, we have suggested more progressive method by strengthening the merits and removing the demerits.

• Journal of Acupuncture Research
• /
• v.18 no.5
• /
• pp.185-194
• /
• 2001

Objective : By process of treatment for a case which diagnosed as Atlanto-Axial Fracture-Dislocation and admitted from the 2nd, December, 2000 to the 18th, December, 2000, the results are as follows. Methods : Clinical observation and analysis about a case of Atlanto-Axial Fracture-Dislocation was done, who visited Dong-in-dang Oriental Medicine Hospital. This case is managed by integrated therapy of oriental medicine. This patient was diagnosed as stagnation of Ki and stasis of blood(氣滯血瘀), deficiency of Um of the liver and kidneys(肝腎陰虛) and medicated gamisekyung-tang(加味舒經湯) and kanghwalsokdan-tang(羌話續斷湯). As acupucture treatments, we could get the effective results by providing the patient with acupuncture on the nape, shoulder, Lt upper limb and Rt distant point Conclusion : We could get the effective results that case of Atlanto-Axial Fracture-Dislocation with severe rigid neck and Motor disturb of neck, was treated with oriental medicine and acupuncture therapy.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.2
• /
• pp.232-238
• /
• 2009

Flicker, also known as voltage fluctuation, is a newest problem of power quality issues, because it is caused by nonlinear loads such as electrical arc furnace and large-scale induction motor, which are country-widely used as the heavy industries of a country develop. An international standard, International Electrotechnical Commission (IEC) 61000-4-15, was published in 1997 and revised in 2003. With increasing concerns about flicker, its mitigation methods have been also studied. General countermeasures for flicker are divided into three categories: a) enhancing the capacity of supplying system, b) Series elements including series reactor and series capacitor and c) power electronic devices including static VAR compensator (SVC) and static synchronous compensator (STATCOM). This paper introduces how to mitigate the voltage flicker at the point of common coupling (PCC) and presents how to simulate and compare the flicker alleviating effects by each mitigation method, using IEC flickermeter based on the Matlab/Simulink program.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.5
• /
• pp.505-511
• /
• 2011

In this paper, we have developed an automatic velocity control system of a small-sized commercial treadmill (belt length of 1.2 m and width of 0.5 m) which is widely used at home and health centers. The control objective is to automatically adjust the treadmill velocity so that the subject's position is maintained within the track when the subject walks at a variable velocity. The subject's position with respect to a reference point is measured by a low-cost sonar sensor located on the back of the subject. Based on an encoder sensor measurement at the treadmill motor, a state feedback control algorithm with Kalman filter was implemented to determine the velocity of the treadmill. In order to reduce the unnatural inertia force felt by the subject, a predefined acceleration limit was applied, which generated smooth velocity trajectories. The experimental results demonstrate the effectiveness of the proposed method in providing successful velocity changes in response to variable velocity walking without causing significant inertia force to the subject. In the pilot study with three subjects, users could change their walking velocity easily and naturally with small deviations during slow, medium, and fast walking. The proposed automatic velocity control algorithm can potentially be applied to any locomotion interface in an economical way without having to use sophisticated and expensive sensors and larger treadmills.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.170-175
• /
• 2003

A control algorithm is developed for highly efficient operation of auxiliary power unit (APU) that consists of a diesel engine and a directly coupled induction generator in series hybrid electric Bus (SHEB). In a series hybrid configuration the APU supplies the electric power needed for maintaining the state of charge (SOC) of the battery unit in various conditions of vehicle operation. As the rotational speed of generator does not depend on the vehicle speed, an optimized operation of engine-generator unit based on the efficiency map of each component can be achieved. The output torque of diesel engine can be controlled by the amount of fuel injection, and the power converted from mechanical to electrical energy can be adjusted by generate control unit (GCU) using the decoupling vector control of torque and flux. As for the given reference of the generating power, the multiply of speed and torque, many combinations of operating speed and torque are possible. The algorithm decides the new operating point based on the engine efficiency map and generator characteristic curve. During the transition of operating points, the speed controller saturation is avoided using variable limit and filtering of generator torque reference. A test rig and SHEB consist of a 1.5L diesel engine and a 30kw induction generator are constructed by Hyundai Motor Company.