• Electric Engineers Magazine
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• v.220 no.12
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• pp.49-56
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• 2000

최근 정보, 통신, 제어기술의 발달에 따라 정보통신기기, 정밀제어기기, 사무자동화기기, 전산기기, 자동생산라인 등에 마이크로프로세서 및 전력용 반도체 소자의 대거 도입, 고효율 속도제어용 모터와 역률 보상용 콘덴서의 사용, 그리고 경제발전과 산업활성화 등으로 인한 고정밀 단일 대형부하의 증가, 도시화로 인한 대규모 공장용 수용가 등이 증대되고 있는 실정이다.

• Electric Engineers Magazine
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• v.242 no.10
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• pp.15-18
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• 2002

진상용 콘덴서를 설치하여 항상 높은 역률을 유지하고 전기설비를 효율적으로 이용하려면 부하의 변동에 맞추어 필요한 진상 용량만 공급하도록 콘덴서를 개폐 제어해야 한다. 수동 조작으로 제어하기 때문에 비현실적인 경우가 많다.또한 전원측과 보상으로 인한 손실 증대를 막기 위해 공장설비에는 콘덴서 자동제어방식이 많이 있으며 건축 전기설비의 경우도 건물의 용도와 규모에 따라 적절한 제어 방식이 적용되고 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.603-604
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• 2008

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.951-959
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• 2013

In order to improve the speed performance of the direct drive mechanical systems, a comprehensive analysis of the velocity ripples of blushless DC motors should be required. Every motor has a certain level of torque ripples when it generates power, and the generated torque ripple also makes the velocity ripples in the final output stage in speed control system. In this paper, a novel algorithm for reducing velocity ripples is proposed based on the modeling of torque ripples for BLDC motors. Various algorithms have been made for torque ripples, but usually they should be installed inside the amplifier logic, result in the difficulties of flexibility for various kinds of torque ripples. The proposed algorithm was developed for being ported in the controller not the amplifier, and it has the capability of the automatic compensation adjustment. The performance of the proposed algorithm was verified by effective simulations and experiments.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2407-2414
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• 1992

Constant temperature hot wire air flow meter for automobiles requires temperature compensation system because hot wire output signal is sensitive to ambient temperature variations as well as fluid velocity. The objectives of the present study are to design an air flow meter circuit which is capable of compensating the hot wire output signal for ambient temperature variations and to investigate the mechanism of such temperature compensation. This circuit is composed of platinum hot wire, platinum resistor, two variable resistors, a constant resistor and a DC-amplifier. In particular, by simply replacing a constant resistor in one of the bridge arms of the conventional circuit with platinum resistor and a variable resistor for the purpose of temperature compensation, the deviation of output signal with respect to ambient temperature variations between 27deg. C 70deg. C could be reduced to less than 2.5% for mass flow rate and to less than 5% for velocity respectively. The mechanism of temperature compensation against ambient temperature variations was explained by means of measuring the heat transfer coefficient with hot wire temperature variations and analyzing and analyzing conventional empirical equations qualitatively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.630-637
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• 2003

This paper explains the impact of frequency error on the performance of WCDMA mobile communication systems and what brings about the frequency error between the base station and the mobile station, and then presents automatic frequency error correction method in mobile receiver. On the basis of system requirement related to frequency stability, the integration test between the base station and the mobile station was accomplished. After applying automatic frequency error correction to mobile receiver, 4 Hz of frequency error at transmitting frequency was obtained. The result met frequency error requirement of ${\pm}$0.1 ppm(about ${\pm}$200 ㎐). Performance degradation due to frequency error was measured by means of Error Vector Magnitude(EVM) at transmitter and Ec/Io at receiver, respectively and then the interface requirement between Modem control signal and RF was suggested to improve the correctness of frequency error control.

• Journal of Engineering Education Research
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• v.8 no.1
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• pp.5-19
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• 2005

This paper describes the design and fabrication of magnetic levitation kits for use in the hands on experiments of automatic control, digital control and microprocessor applications in the division of mechatronics in Samcheok university. The kits are developed inspired by MIT's design, but it is designed on the digital basis, whereas MIT's is designed on the analog basis. As a result, the kits can be monitored and controlled on the analog and digital control techniques. Furthermore, the cost of kit components is comparable or lower to that of MIT design. And the kits can be controlled with magnetic hall sensors and/or infrared sensors, which provides more versatile experience on the use of sensors and signal filtering to the students. The design is fabricated and tested by authors and will be provided to the students as lab projects. The kits will be intentionally presented with a device that is poorly instrumented and poorly compensated. And the students are expected to analyze sensor signal and controller performance, and then, perform compensator design and signal filtering.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.903-909
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• 2018

In this paper, performance analysis of machine vision techniques is presented to improve the convenience and speed of automatic inspection in the industrial field when machine vision is applied to the image not taken in the stationary state, but in the moving state on a conveyer. When the length of cylindrical rods used for automobiles was measured using the edge detection method, the conveying speed increased, and the uncertainty of the boundary between the background and the part image increased, which resulted in a shorter image of the object taken. This paper proposes a linear compensation method to predict the biased errors of the length measurements after examining the pattern of biased and random errors, respectively, with 6 different types of specimens and 7 velocity stages. The length measurement corrected by the linear compensation method had the same accuracy as the stationary state within the speed range of 30 cm/s and could enhance the application capability in automatic inspections.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.4
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• pp.100-106
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• 2011

Radio Frequency (RF) signal fluctuates dynamically in wireless communication environments, where this fluctuation is severe especially in vehicular environments. Automatic Gain Control (AGC) is critical in wireless communications to establish reliable communication links and compensate the received signal fluctuation. In this paper, we introduce a simple and novel AGC scheme which uses both Received Signal Strength Indicator (RSSI) and analog-to digital converter (ADC) signals. Performance enhancement of the proposed AGC scheme is verified with practical measurements including simulations.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.98-104
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• 2006

The conventional burst-mode APC(Automatic Power Control) circuit had an effective structure that was suitable for a low power consumption and a monolithic chip. However, as data rate was increased, it caused errors due to the effect of the zero density. In this paper, we invented a new structured peak-comparator which could compensate the unbalance of the injected currents using double gated MOS and MOS diode. And we proposed a new burst-mode APC adopting it. The new peak-comparator in the proposed APC was very robust to zero density variations maintaining the correct decision point of the current comparison at high data rate. It was also suitable for a low power consumption and a monolithic chip due to lack of large capacitors.