• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.11
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• pp.920-923
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• 2017

In this paper, we design the internal parameters of the SIMO channel sounder suitable for the measurement of the high-speed travel environment channel, and measure the characteristics of the wide-band channel by applying the proposed measurement method to the Yeoju Smart Highway piloted at 5.89 GHz C-ITS. Based on the design of the receiving array structure suitable for the real environment, the linear slope compensation method for the Doppler phase shift is applied to provide a reliable result on the Doppler effect due to the incoming angle information and the surrounding environment in the multipath environment.

• Journal of Wind Energy
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• v.9 no.4
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• pp.47-56
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• 2018

This paper introduces an active power dependent standard characteristic curve, Q(P) to compensate for voltage variations due to the output of distributed generation. This paper presents an efficient control method of grid-connected inverters by comparing and analyzing voltage variation magnitude and line loss according to the compensation method. Voltage variations are caused not only by active power, but also by the change of reactive power flowing in the line. In particular, the system is in a relatively remote place in a coastal area compared with existing power plants, so it is relatively weak and may not be suitable for voltage control. So, since it is very important to keep the voltage below the normal voltage limit within the specified inverter capacity and to minimize line loss due to the reactive power. we describe the active power dependent standard characteristic curve, Q(P) method and verify the magnitude of voltage variation by simulation. Finally, the characteristics of each control method and line loss are compared and analyzed.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.164-170
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• 2004

Misfiring is often observed during the high temperature quality assurance test of plasma display panel. This limits the productivity of PDP industry. In this paper, experimental observations on the misfiring at high panel temperature have been performed through time dependent discharge light output and static margin measurement. For the high temperature condition, firing voltage increment is found in both surface and facing discharges. This in turn increases time lag in address discharge, and results in increment of misfiring probability. In order to reduce this kind of misfiring, a new method that applies automatically different slope of ramp erasing pulse on the common electrode according to temperature variation is proposed. The experimental results show that controlling the slope of ramp erasing pulse is quite effective for compensating temperature-dependent variation of reset and address discharge.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.6A
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• pp.782-793
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• 2000

This paper presents a simple dynamical prediction scheme of the signal level which is attenuated and varied due to rain fading in satellite communication links using above 10GHz frequency bands. The proposed prediction scheme has four functional blocks for discrete-time low-pass filtering, slope-based prediction, mean-error correction and hybrid fixed/variable prediction margin allocation. Through simulations using Ka-band attenuation data obtained from the data measured over Ku-band by frequency-scaling, it is shown that the slope-based prediction with the mean-error correction has as small standard deviation of prediction error as below 1 dB, and that the error is about 1.5 to 2.5 times as small as that without the mean-error correction. The hybrid prediction margin allocation requires smaller average margin than those of both fixed and variable methods.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.6
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• pp.389-396
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• 2016

The sealing robot must be able to calculate the slope of a contact surface for complete adherence of the sealing on different concrete shapes. After the slope is obtained, the robot will track on the surface of the concrete, but this process contains an error in the actual purpose of the force command. The reason this a phenomenon occurs, the non-linearity of the contact surface and the end-effector, is due to parasitic coupling. Errors like make it difficult to measure accurately the respective factors. Therefore, it is regarded as a disturbance that occurs when it follows the work surface it. In this paper, we selected the friction coefficient of the surface as a control factor and designed a compensator to reduce effects of disturbance. Finally, in view of the non-linearity of the end-effector of a robot to contact surfaces directly, we propose a robust force tracking controller in the finite range for managing disturbances that occur during the sealing.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.381-382
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• 2007

Recently fishing industry is interested in efficient and automated fishing implementations to reach the level of the international leading technology. One of the important device used in fishing boat is an automated electric compass that harnesses the GPS and terrestrial magnetic sensor. The electric compass is desired to be minimized in size while keeping a high effectiveness in the characteristic of a magnetic compass. This device also can be used as a heading angle sensor to construct auto-navigation system in a small size of ships. However, there exists measurement errors induced from the slope of terrestrial magnetic sensor caused by the motion of boat. In this paper, a method has been proposed removing the measurement error arising from the slope of terrestrial magnetic sensor when the ship is in motion. We have designed a sensor with two DOF(degree of freedom) and a weight to maintain the horizontality of the sensor. Through this research, the hardware has been designed and also a test has been performed. The test shows a promissory result.

• Smart Structures and Systems
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• v.19 no.3
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• pp.269-277
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• 2017

Recently, there has been significant interest in structural health monitoring for civil engineering applications. In this research, a specially designed tendon, proposed by embedding FBG sensors into the center king cable of a 7-wire strand tendon, was applied for long-term health monitoring of tensile forces on a ground anchor. To make temperature independent sensors, the effective temperature compensation of FBG sensors must be considered. The temperature sensitivity coefficient ${\beta}^{\prime}$ of the FBG sensors embedded tendon was successfully determined to be $2.0{\times}10^{-5}^{\circ}C^{-1}$ through calibrated tests in both a model rock body and a laboratory heat chamber. Furthermore, the obtained result for ${\beta}^{\prime}$ was formally verified through the ground temperature measurement test, expectedly. As a result, the ground temperature measured by a thermometer showed good agreement compared to that measured by the proposed FBG sensor, which was calibrated considering to the temperature sensitivity coefficient ${\beta}^{\prime}$. Finally, four prototype ground anchors including two tension ground anchors and two compression ground anchors made by replacing a tendon with the proposed smart tendon were installed into an actual slope at the Yeosu site. Tensile forces, after temperature compensation was taken into account using the verified temperature sensitivity coefficient ${\beta}^{\prime}$ and ground temperature obtained from the Korean Meteorological Administration (KMA) have been monitored for over one year, and the results were very consistent to those measured from the load cell, interestingly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1973-1980
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• 2017

In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method.

• Journal of Sensor Science and Technology
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• v.26 no.3
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• pp.168-172
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• 2017

A nondispersive infrared (NDIR) ethanol gas sensor was prototyped with ASIC implemented thermopile sensor, which included a temperature sensor and two ellipsoidal waveguide structures. The temperature dependency of the two ethanol sensors (with partially blocked and intact structures) has been characterized. The two ethanol gas sensors showed linear output voltages initially when varying the ambient temperature from 253 K to 333 K. The slope of the temperature sensor presented a constant value of 15 mV/K. After temperature compensation, the ethanol gas sensor estimated ethanol concentrations with larger errors of 20 to 25% below 200 ppm. However, the estimation errors were reduced to between -10 and +1 % from 253 K to 333 K above 200 ppm ethanol gas concentration in this research.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2682-2684
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• 1999

This paper presents design and stability analysis of the constant frequency Flyback type converter using average current-mode control. The average current-mode control has been recently reported, and superior characteristics over a peak current-mode control such as a good tracking performance of an average current, no slope compensation and noise immunity. By the improvement of PM(Phase Margin) obt from applying the compensator in the current loop, the stability of designed flyback convert more improved. The validity of designed convert confirmed by simulation and experimental result