• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.6
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• pp.295-301
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• 2001

In this paper, an impedance control using a serial chain of spring-damper system is proposed for a vehicle platoon. For safety of the vehicle platoon, it is required to regulated the distance between each vehicle at a preassigned value even in case of vehicle model error, or moise in the measurement signal. Since the spring-damper system is physically stable and widely used to represent the interaction with the uncertain environments, it is appropriate to the longitudinal control of the vehicle platoon. By considering the nonholonomic characteristics of the vehicle motion, the lateral control and the longitudinal control of the vehicle paltoon are unified in the proposed algorithm. Computer simulation is carried out to verify the robustness against the uncertainties such as the vehicle model error and the measurement noise.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2305-2307
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• 1999

Partial discharge measurement using a ultrasonic technique allows us to detect degradation of the electrical insulation in a power transformer. However, The ultrasonic measurement studies don't offer a good solution in operating conditions. In this paper, we investigated characteristics of ultrasonic noise caused by a 345kV power transformer under operating conditions. The ultrasonic noises generated by corona in air, vibration of core, pump and fan, etc. An ultrasonic frequency caused by corona in air was appeared 9 and 18[MHz] at the outside wall of the transformer. And a spectra of core vibration was detected below 2.5[kHz]. These spectrum were compared with 20 $\sim$ 200[kHz] of the internal partial discharge in the model transformer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.107-109
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• 2003

The magnetostriction of FeCoGe/phenol composites is measured under the external magnetic field. A few Measurement are carried out by using the electrical-resistance strain gage, the Wheaton Bridge for eliminating the unnecessary voltage, the lock-in-amplifier for the signal amplification and noise filtering. When the external magnetic field is applied to the longitudinal direction against those samples which is the 10wt.% phenol in composites, the theoretical maximum strain of 120ppm is obtained. According to the larger strain than that of others solid state actuators and piezoelectric actuators. FeCoGe/phenol composites could be useful as an actuator.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2035-2039
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• 2008

This paper described an on-line condition monitoring device for rotating machines by measurement of unbalance current due to insulation deterioration. The device consists of a zero-phase current transformer (ZCT), a low-noise amplifying circuit, and a microprocessor unit. The prototype device measures current of $500\;{\mu}A\;{\sim}\;30\;mA$ in frequency ranges from 10 Hz to 3 kHz. An application experiment was carried out on 3-phase induction motors and we could measure current changes caused by a short-circuited turn.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.2
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• pp.168-172
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• 2001

The accuracy problem of robot manipulators has long been one of the principal concerns in robot design and control. A practical and economical way of enhancing the manipulator accuracy, without affecting its hardware, is kinematic calibration. In this paper an effective and practical method is presented for kinematic calibration of Stewart platforms. In our method differential errors in kinematical parameters are linearly related to differential errors in the platform pose, expressed through the forward kinematics. The algorithm is tested using simulated measurement in which measurement noise is included.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.122-130
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• 2009

The paper presents an algorithm which uses code vectors to represent comer geometry information for searching the similar images from a database. The comers have been extracted by finding the intersections of the detected lines found using Hough transform. Taking the comer as the center coordinate, the angles of the intersecting lines are determined and are represented using code vectors. A code book has been used to code each comer geometry information and indexes to the code book are generated. For similarity measurement, the histogram of the code book indexes is used. This result in a significant small size feature matrix compared to the algorithms using color features. Experimental results show that use of code vectors is computationally efficient in similarity measurement and the comers being noise invariant produce good results in noisy environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.830-838
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• 2000

This paper represents measurement prodcedure and analysis of terrestrial DTV field test results over Taejeon city area. Thirty three points were selected as measuring points. Signal power, noise power, Segment Error Rate, RMS delay spread and equalizer performance was measured. The video and audio quality of DTV was good over half of test sites. Equalizer, could correct signal ghost and improve S/N up to 13.7 dB. From this test, the test procedure for DTV will be estabilished.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.1
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• pp.41-48
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• 2014

This paper analyzes the Monte Carlo localization (MCL) method, which estimates the pose of an indoor mobile robot. A mobile robot must know where it is to navigate in an indoor environment. The MCL technique is one of the most influential and popular techniques for estimation of robot position and orientation using a particle filter. For the analysis, we perform experiments in an indoor environment with a differential drive robot and ultrasonic range sensor system. The analysis uses MATLAB for implementation of the MCL and investigates the effects of the control parameters on the MCL performance. The control parameters are the uncertainty of the motion model of the mobile robot and the noise level of the measurement model of the range sensor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.4
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• pp.253-257
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• 2017

Nowadays, it is increasingly important to detect whether cables are live for the operator's safety if there is a sudden power failure. It is especially hard to detect the electrical field of an underground line because of shielding. This paper on detection of live-line states in cables studied the detection characteristics of the change in the magnetic field and axis as the frequency, voltage, and distance at the same load are changed using 3 axes. A search coil type was used as a magnetic field sensor with non-contact. We found that magnetic fields decrease proportionally to the square of the distance and the decrease of rated voltage with load effected to magnetic field. The magnetic field was detected by 3-axis sensors given correct proximity, but appeared as noise components beyond a distance of 2 cm.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.3
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• pp.143-152
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• 2002

Frequency is regarded as one of most important indices for the operating power systems. Several digital techniques for measuring frequency have been presented in the last decades. This paper proposes a design and implementation an adaptive scheme using phase angle difference calculation fort frequency measuring in power system. The advantages of the proposed technique are demonstrated by fault signals from EMTP simulation and user defined arbitrary signals by Excel program. The proposed technique is compared with the conventional methods. Performance teat results indicate that the proposed technique provides accurate measures in pretence of noise and harmonics and in case faults and is suitable for measurement near-nominal, nominal. and off-nominal frequencies. We can see that It will be useful in microprocessor based relays and digital metiers that need to measure power system frequency.