• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.675-680
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• 2012

Wind energy is currently the fastest growing source of renewable energy used for electrical generation around the world. Wind farms are adding a significant amount of electrical generation capacity. The increase in the number of wind farms has led to the need for more effective operation and maintenance. CMS(Condition Monitoring System) can be used to aid plant operator in achieving these goals. Its aim is to provide operators with information regarding th e health of their machine, which in turn, can help them improve operation efficiency. In this work, wind turbine fault diagnostic algorithm which can diagnose the mass unbalance and aerodynamic asymmetry of the blades is proposed. Proposed diagnostic algorithm utilizes both FFT(Fast Feurier Transform) of the signal from accelerometers installed inside of nacelle and simple diagnostic logic. Furthermore, to verify the applicability of the proposed system, 3W small sized wind turbine system is tested and physical experiments are carried out.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.80-87
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• 2006

In this paper, we analyze the performance of IEEE 802.11b WLAN communication between access point(AP) and mobile equipment(ME) in 2.4 GHz band with noise and interference factors. WLAN communication at in-vehicle environment is assumed as the communication between main vehicle controller and electronic device such as sensor, ECU (Electrical Control Unit) in vehicle on telematics field for implementing wireless vehicle control system. Received interference level from other system's mobile equipment in the same band and automobile noise from each part of vehicle can be the main factors that can cause increasing error rate of control signal. With these (actors, we focus on the Eb/No the BER performance of WLAN for analyzing the characteristic of interference factors by the measured bit error rate.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.538-544
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• 2000

A phased array ultrasonic nondestructive inspection system is being developed to obtain images of the interior of steel structures by modifying a medical ultrasound imaging system. The medical system consists of 64 individual transceiver channels that can drive 128 array elements. Several modifications of the system were required mainly due to the change of sound speed. It was necessary to fabricate array transducers for steel structure and to obtain A-scan signal that is necessary for the nondestructive testing. Boundary diffraction wave model was used for the prediction of radiation beam field from array transducers, which provided guidelines to design array transducers. And a RF data acquisition board was fabricated for the A-scan signal acquisition along a selected un line within an image. For the proper beam forming in the transmission and reception for steel structure, delay time was controlled. To demonstrate the performance of the developed system and fabricated transducers, images of artificial specimens and A-scan signals for selected scan lines were obtained in a real time fashion.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.1075-1081
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• 2011

In this paper, we proposed the DS-SS modem-based communication system for long distance wireless-transmission. The module we designed in this approach contained both convolution encoder and gold-code generator, which aimed at error correcting, T-DES encryption algorithm and spread-spectrum as well. It embodied PC-based GUI program in order to control the such command signal as data transceiver. This program also used to control the specific FPGA/MCU which is able to verify and interface to the modem. We demonstrated the communication system to verify its proper operation by using GUI program and designed hardware. A set of experiments are conducted and as a result, proposed communication system is well operated as the design specification.

• Journal of IKEEE
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• v.22 no.2
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• pp.510-513
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• 2018

Recently, EMC (electromagnetic compatibility) becomes very important, which demands the measurement of EMI (electromagnetic interference) in the chip level. NFS (near-field scanning) systems defined in IEC 61967 and IEC 62508 are typical methods to analyze EMI in the chip level. As chips becomes faster, frequency measurement of NFS system should become wideband, but it degrades SNR (singal-to-noise ratio) of the NFP (near-field probe). This paper surveys SNR enhancement technologies of the NFS while maintaining wideband characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.516-521
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• 2005

The application of UWB not only complies with the requirements of remote sensors system(ECG), it also contributes to the effectiveness of the implementations through its unique qualities such as ultra low transmission power - an important factor when dealing with biomedical equipment. In this paper, the aim is to replace the wired ECG sensors with a wireless link and design wireless UWB communication system. The various pulse shapes are presented that satisfies the FCC spectral mask and FCC part 15 rule. It is shown that UWB can be a high rate transmission over short ranges using Rake receiver, with the capability for reliably transmitting 100Mbps over distance at about 10 meters.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.349-352
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• 2009

최근 유비쿼터스 헬스케어가 부각됨에 따라 심장의 활동상태를 보다 편리하게 측정하기 위하여 이동성 및 휴대성을 강조한 심전도 계측 시스템 및 스트레스 상태를 분석하기 위한 연구들이 수행되고 있다. 하지만 기존 심전도 계측은 전극의 부착 및 계측시스템과의 연결을 위한 리드선의 사용으로 인해 활동의 불편함을 유발한다. 본 연구에서는 기 연구 수행된 가정 또는 사무실에서 무구속적인(unconstrained) 방법으로 지속적인 심장의 활동상태의 모니터링이 가능한 무구속 의자형 심탄도 계측 시스템을 구현하였다. 무구속적인 방법으로 심탄도 신호를 계측하고 심탄도신호로부터 심박동변이율을 추출함으로써 일상생활 중 스트레스를 모니터링 하고자 하였다. 구현된 시스템을 통한 스트레스 모니터링의 가능성을 평가하기위하여 안정상태의 심박동변이율과 인위적인 신체적 스트레스인 Valsalva 조작를 유도한 후 심박동 변이율을 비교평가 하였다. 건강한 대학생 10명을 대상으로 비교분석을 수행한 결과 안정 상태와 육체적 스트레스 인가 후 심박동 변이율의 변화 양상을 관찰할 수 있었으며, 무구속적인 방법에 의해 스트레스의 모니터링이 가능함을 확인 할 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.151-157
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• 2004

In this paper, we investigated ultra high speed wireless communication cell backbone net of city using of wireless communication transceiver for millimeter wave band. A new type of 60GHz wave band wireless transceiver using NRD waveguide. This 60㎓ transceiver has excellent signal's absorption characteristics of oxygen molecule than the other millimeter wave bands. We constructed to wireless networks interval within 500m to 3km on wireless backbone node using 60GHz transceivers, and did it so that city type wireless communication cell backbone networks of 155.52MbpsATM(OC-3) may be possible. Therefore, if use transceiver, it is possible that city type ultra high speed wireless communication cell backbone networks construction of 100Mbps, 155.52Mbps, 622Mbps, 1Gbps, and 1.2Gbps degrees.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.54-57
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• 2009

The propellant level measurement system of the next Koreanized launch vehicle shall adapt a capacitive type sensor, which can generate capacitive values continuously considering cryogenic environment and the characteristics of flowrate control. At present there are a twin-arc and a triple-arc methods as a capacitive type signal sensing method. In this study a highly accurate triple-arc method, which can apply to almost all fluids, is chosen. In this paper the review results on the principle of triple-arc sensing, the analysis results on the influence on capacitive values due to shape change of sensing part, and the simulation results to monitor the influence on signal sensing according to the location of sensing part in the upper part of propellant tank are included. Information obtained from this study can be used in the designing and manufacturing of on-board propellant level measurement system in tanks.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.78-83
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• 2007

Robot collects surrounding information to recognize tile unknown environment by using various sensors such as visual, infrared ray and ultra sonic sensors. Although visual sensor is the most popular one, it has some difficulties in collecting data in dark or too bright environment due to sensitivity of the light. It also requests significant amount of calculation on collecting data from certain images with marked, straight and curved ones. As an alternative, ultra sonic sensor can simply overcome this visual sensing system's flaw and easily be used. It is easier than visual system, especially in case of collecting data on object and distance in dark environment. Ultra sonic sensor can replace the expensive visual sensing system not only in avoiding obstacles but also in reaching to the target area smoothly. The purpose of this paper is to develop the algorithm to optimize the environmental recognition, path planning and free-ranging by minimizing errors caused by inaccurate information and by considering characteristics of the ultra sonic rays such as refraction and diffusion. This paper also realizes the system that can recognize the environment and make the appropriate path planning by applying the algorithm on this moving robot.