• Proceedings of the KSME Conference
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• 2004.11a
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• pp.708-713
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• 2004

This research develops a sensorless hydraulic servo system of Parallel-Typed robot for harbour construction. Purpose of the robot is to mechanize the construction, which is accomplished through a joystick's operating by a stoneworker (or diver). The robot is attached on the end of an excavator as its attachment or transported by a crane to reach the desired place. The embedded compact controller is installed on the robot body and controlled by wireless telecommunication. For underwater work, it is necessary to waterproof the robot and its sensors. Especially, a sensor waterproof is a main drawback for the underwater robot. This leads us to develop a hydraulic robot position controller using an observer which gives the position information without any position sensor. We design a neural network to identify the displacement change according to the command voltage to servo valve. To verify the sensorless controller, this paper presents the performance of the sensorless control for which the position is given by the observer comparing with that of the sensor control for which the position is measured by LVDT sensors.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1056-1061
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• 2013

The widely used motors in HEV(Hybrid Electric Vehicles) are IPMSM(Interior Permanent Magnet Synchronous Motor) which has no rotor heat, higher efficiency and advantageous in volume and weight comparing with other motors. For vector control of IPMSM, position information of rotor is required but Resolver is mainly used as the detecting sensor. However, the use of position sensors will reduce the system reliability of hybrid electric vehicles. In this paper, a way to control the motor by sensorless was proposed at the event of sensor failure. We also implemented IPMSM sensorless operation by the expanded EMF(Electro Motive Force) voltage way and harmonic voltage which is applying in the low speed area. And we proposed how to change with sensorless control by detecting the position sensors failure and verified it through experiments.

• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.166-172
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• 1998

Switched reluctance motor(SRM) has the advantages of simple structure, low rotor inertia and high efficiency. However, position sensor is essential in SRM in order to synchronize the phase excitation to the rotor Position. The Position sensors increase the cost of drive system and tend to reduce system reliability. This paper investigates the speed control of sensorless SRM in which the Phase current and change rate are utilized in position decision, and the period of dwell angle is variable for speed control. The proposed system consists of Position decision circuit, speed controller, digital logic commutator, switching angle controller and inverter The performances in the proposed system are verified through the experiment.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.4
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• pp.55-64
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• 2001

In this study, hemisphere and cylindrical shapes were machined for different tool paths and machining conditions with ball endmill cutters. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting is obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. Roundness values were found in least roundness error when down-milling in upward cutting. It is obtained the very little difference between 90。and 45。 of inclination position angle. The best surface roughness value was obtained in upward up-milling and showed different tendency with tool deflection and cutting force. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. Therefore, this phenomenon which is received over cutting resistance can be caused of chatter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.181-184
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• 2003

In this paper, we investigated the position-dependent stress distribution of indium-tin-oxide (ITO) film on Polycarbonate (PC) substrate by external bending force. It was found that there are the maximum crack density at the center position and decreasing crack density as goes to the edge. In accordance with crack distribution, it was observed that the change of electrical resistivity of ITO islands is maximum at the center and decrease as goes to the edge. From the result that crack density is increasing at same island position as face-plate distance (L) decreases, it is evident that the more stress is imposed on same island position as L decreases.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.3
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• pp.436-447
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• 1993

This study concerns the role of costume in Shakespearean tragedy from the viewpoint of the role theory. The term "role" has been used to represent the behavior expected of the occupant of a given position or status. A specific role can not be successfully performed without the aid of the Costumes. Costumes are adopted in relation with a specific role. The role of social status and position reflects sex, age, occupation, class, economic position of the characters. In his works, the crown and the mace represented not only the throne but also a previllege and supreme position. The sitution role of costume could be widely used for visualizing the psychological situation and external environments of the characters on the stage. The disguise role hided one's status, thereby makes possible acting others position. And the disguise role can bring about the change of status, age, sex, occupation, and atmosphere. The costume could be used as a voucher of love. The costume performed the role of the physical and psychic protection, and provided its wearer with consolation and peaceful mind. The costume reflected the custom of a society through its wearing condition and wearing configuration. The results obtained from this study can provide useful cues for understanding the role action in the social structure. This kind of understanding reveals the costume phenomena in real life, allows one to perform roles properly and efficiently, and opens our insight on the overall aspects of the costume culture.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.775-781
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• 2011

For the measurement of absolute position of mobile robot in indoor environments, the ultrasonic positioning systems using ultrasound have been researched for several years. Most of these ultrasonic positioning systems to avoid interference between the ultrasound are used for sequential transmitting. However, due to the use of sequential transmitting, the positions of transmitter to receive an ultrasound will change when the mobile robot moves. Therefore the accuracy of positioning is reduced. In this paper, the new position estimation algorithm with weighting factor according to the time of receipt is proposed. By applying the proposed algorithm to existing Ultrasonic Satellite System(USAT), the improved USAT is configured. The positioning performance of the improved USAT with the proposed position estimation algorithm are verified by experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.550-556
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• 2008

The aim of this research is to analyze the influence of motive pressure, driving nozzle position and nozzle throat ratio on the performance of ejector. The experiment was conducted in the variation of motive pressure of 0.196, 0.294, 0.392 and 0.490MPa respectively. The position of driving nozzle was varied in difference locations according to mixing tube diameter(0.5d, 1d, 2d, 3d, 4.15d, 5d and 6d). The experimental results show when the nozzle outlet is located at 3d, the flow characteristics change abruptly. It is shown that the suction flow rate and pressure lift ratio of ejector is influenced by the driving nozzle position. At nozzle position location of the Id of mixing tube diameter the performance of ejector gives the best performance.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.19-25
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• 2016

Using a actuator to which the motor and the gear is applied to the I-PD control method and a dual-loop system to carry out precise position control. I-PD control algorithm performs an operation to reduce the overshoot in the transient response. Accordingly, the actuator obtains a precise position tracking result. Also it utilizes two sensors and dual loops. It reduces the adverse effect on the precise position control that may occur by the end play of the gear train. In this paper, we uses the actuator model applying the BLDC motor and gear in order to determine the position tracking result by the dynamic characteristic change. It was verified by the simulation results.

• The korean journal of orthodontics
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• v.27 no.4 s.63
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• pp.569-584
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• 1997

The present study assessed the effects of Rapid Maxillary Expansion on head posture and hyoid bone position. For this study, 32 Angle's class III patients - hellman 3c $\~$ adult stage, mean age 12y9m - were selected and divided into two groups, A,B according to craniocervical angulation. Craniocervical angulation Increased in Group A and decreased in Group B after the therapy. And 23 Angle's class I persons $\~$ same hellman stage, mean age 12y7m $\~$ were selected (or the control group. Cephalometric analysis of skeletal pattern, pharyngeal space, head posture, hyoid bone position was performed. The results were as follows, 1. Comparison of skeletal pattern and pharyngeal space 1) All two groups(A,B) had Mandibular plane inclined inferiorly and no pharyngeal space change was obseved after RME therapy 2) Skeletal pattern and pharyngeal space of Group A, B were normal before and after treatment. 2. Comparison of head posture 1) Craniocervical angulation of Group A was increased after treatment. That of Group B was decreased and mandibular plane was inclined inferiorly after treatment. 2) Before treatment, craniocervical inclination was normal in Group A but larger than normal in Group B. After treatment, all two groups(A, B) had normal craniocervical angulation. 3. Comparison of hyoid bone position 1) After treatment, long axis of hyoid in Group A, B was not changed. Antero- posteriorly, hyoid position was changed posteriorly in Group A but no change was founded in Group B after treatment. Vertically, hyoid bone position were not changed in two groups except increase in APHFH in Group A after treatment 2) Long axis of hyoid bone was normal in Group A, B before and after treatment. Anteroposteriorly, hyoid bone position was more anterior than Group B, C before treatment but all the position of two groups had normal position after treatment. Vertical position of hyoid bone was normal in all two groups before and after treatment.