• Phonetics and Speech Sciences
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• v.8 no.1
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• pp.19-24
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• 2016

The Korean high back vowels /o/ and /u/ have been reported to be in a state of near-merger especially among young female speakers. Along with cross-generational changes, the vowel position within a word has been reported to render different phonetic realization. The current study examines native English speakers' ability to attend to the phonetic cues that distinguish the two merging vowels and the positional effects (word-initial vs. word-final) on the identification accuracy. 28 two-syllable words containing /o/ or /u/ in either initial or final position were produced by native female Korean speakers. The CV part of each target word were excised and presented to six native English speakers. The results showed that although the identification accuracy was the lowest for /o/ in word- final position (41%), it increased up to 80% in word-initial position. The acoustic analyses of the target vowels showed that /o/ and /u/ were differentiated on the height dimension only in word-initial position, suggesting that English speakers may have perceived the distinctive F1 difference retained in the prominent position.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.494-502
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• 2007

Ubiquitous location based services (u-LBS) will be interested to an important services. They can easily recognize object position at anytime, anywhere. At present, many researchers are making a study of the position recognition and tracking. This paper consists of postion recognition and user identification system. The position recognition is based on location under services (LBS) using a signal strength map, a database is previously made use of empirical measured received signal strength indicator (RSSI). The user identification system automatically controls instruments which is located in home. Moreover users are able to measures body signal freely. We implemented the multi-hop routing method using the Star-Mesh networks. Also, we use the sensor devices which are satisfied with the IEEE 802.15.4 specification. The used devices are the Nano-24 modules in Octacomm Co. Ltd. A RSSI is very important factor in position recognition analysis. It makes use of the way that decides position recognition and user identification in narrow indoor space. In experiments, we can analyze properties of the RSSI, draw the parameter about position recognition. The experimental result is that RSSI value is attenuated according to increasing distances. It also derives property of the radio frequency (RF) signal. Moreover, we express the monitoring program using the Microsoft C#. Finally, the proposed methods are expected to protect a sudden death and an accident in home.

• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.186-191
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• 2006

The perception of English labial consonants was investigated via experiment where 40 Korean EFL learners identified nonwords with the target labial consonants [p, b, f, v] in 4 different prosodic locations: initial onset position, intervocalic position before stress, intervocalic position after stress, and final coda position. The overall result showed that the proportion of perception accuracy of the target consonants was rather low, amounting to only 55%. There was also a positional effect since the accuracy rates for perceiving the four target consonants differed by position. Specifically, the average accuracy rate of the target consonant identification was higher in intervocalic position before stress (70%) and initial onset position (67%) than in intervocalic position after stress (45%) and final coda position (36%). Further, the accuracy rate for [f] is was high in all prosodic locations except intervocalic position after stress. The perception patterns were accounted for by the markedness and perceptual factors in conjunction with stress location.

• Journal of Power Electronics
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• v.10 no.1
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• pp.58-64
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• 2010

In this paper, the dynamic performance of oscillating linear motors, which are used in household refrigerators, is improved by means of efficient parameter identification. Oscillating linear motor parameters are identified as a function of the piston position and the motor current. They are stored in a ROM table and used later for an accurate estimation of piston position. The identified motor parameters are also approximated to the $2^{nd}$-order surface functions, which are divided into 2 or 4 subsections in order to decrease identification errors. Experimental results are given to show that the proposed control scheme can provide oscillating linear motors with high dynamic performance.

• Journal of Power System Engineering
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• v.15 no.2
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• pp.69-77
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• 2011

In this paper, an optimal PID sliding mode controller is proposed for the position control of electro-hydrostatic actuator(ERA) systems with system uncertainties and saturation in the motor. An ERA prototype is developed and system modeling and parameter identification are executed. Then, optimal PID and optimal anti-windup PID controller are designed based on identified system model by using optimization toolbox in MA TLAB/Simulink and the performance of the two control systems are compared by experiment. It was found that the optimal anti-windup PID control system has better performance than the optimal anti-windup PID control system.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.4
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• pp.23-31
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• 2010

As the analysis and design technologies for electro-magnetic actuation has advanced over the years, proportional solenoid valve is gaining acceptance in wide range of industrial and commercial applications because of its superior characteristics over the conventional AOV or MOV, such as improved performance, reduced maintenance costs. This research deals with the position controller design of two-stage flow control solenoid valve. Investigation of steady-state characteristics and dynamic model identification for pilot disc is performed. Least square method to minimize the error magnitude of frequency response between the closed-loop and target system is applied to the design of PI-controller gains. From the experiments of step and frequency response, it is concluded that the controller meets the performance specification of target system, which verifies the usefulness of controller design method for proportional solenoid valve.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.228-232
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• 2004

This paper is to identify the position of random disturbance on flexible dynamic system, and the position of the piezo ceramic actuator 0 minimize tip response. Correlation of the output signals from each parts on flexible system is used to identify the position of random disturbance. Except the correlation with an output signal from the position of random disturbance, other correlations have time delay. This is a base idea to identify the position on this study.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.184-189
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• 2013

This paper proposes a method for improving the performance of a position sensorless control system for a slotless surface permanent magnet synchronous motor (SPMSM) in a very low-speed region. In position sensorless control based on a motor model, accurate motor parameters are required because parameter errors would affect position estimation accuracy. Therefore, online parameter identification is applied in the proposed system. The error between the reference voltage and the voltage applied to the motor is also affect position estimation accuracy and stability, thus it is compensated to ensure accuracy and stability of the sensorless control system. In this study, two voltage error compensation methods are used, and the effects of the compensation methods are discussed. The performance of the proposed sensorless control method is evaluated by experimental results.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.61-68
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• 2012

In this paper, a closed-loop sensorless stroke control system for a linear compressor has been designed. In order to estimate the piston position accurately, motor parameters are identified as a function of the piston position and the motor current. These parameters are stored in ROM table and used later for the accurate estimation of piston position. The identified motor parameters are approximated to the several surface functions in order to decrease memory size. They can also be divided into 2 or 4 subsections to decrease identification errors. The effect of the order of surface functions and division of subsections on identification errors and computation time is analyzed.

• Journal of Korea Society of Digital Industry and Information Management
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• v.12 no.1
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• pp.63-69
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• 2016

Although the previous information technologies had been used for the quick and accurate processing of work, At present, however, as the combination with the Internet, the IOT(Internet-of-Things) era in which the diverse pieces of information are collected and handled through the sensor networks is in progress. Among these application fields of the IoT, the indoors position identification technology has been developing in the direction of providing the position information in the buildings of which the lengths and the interiors are complicated and in the direction of providing the various pieces of information and others of the like to the nearby customers. In this paper, we proposed an indoors position identification system that detects the patrol positions of the prison officers in the correctional facilities and in the prisons by using the ultrasonic waves, that transmits these to the control system and the data gateway, and that transmits the detected data. The Indoors Positioning identification System is organized with the tags for recognizing the positions that transmit the ultrasonic signal, ultrasonic receiver and data gateway. And the indoors position information data were transmitted to the management system through the data gateway. We evaluated the transmission error, by changing the distance of the proposed system for location recognition tag and the receiver, As a result, we found out that, when the transmission distance was 10 cm or less, the errors occurred in the form of the distortions. And when it was 110 cm or more, the transmission errors occurred due to the propagation diminutions of the ultrasonic wave signals. And when the transmission distance was from 10 cm to 100 cm, it was shown that the proposed system was possible without any errors.