• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1229-1234
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• 2018

In this paper, a fire prevention system based on a broadband powerline communication (PLC) system is implemented and a demonstration experiment is carried out to prevent from or promptly dealing with possible fires within the nacelle of a wind turbine generator system (WTGS). For this purpose, an inductive coupler having satisfactory attenuation characteristic in the frequency region for high-speed PLC is also manufactured. It is confirmed that the implemented system can monitor the environmental change inside the nacelle in real time by transmitting various information obtained by the sensors such as temperature, flame, and smoke sensor installed in the nacelle and thermal image recorded by a thermal camera to the ground control center through the PLC system. Therefore, it is, considered that the implemented system will significantly improve the reliability of the fire monitoring and prevention system of the WTGS in conjunction with the existing safety system.

• Journal of Software Assessment and Valuation
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• v.15 no.1
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• pp.103-107
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• 2019

Recently, many technologies have been developed to realize low power high speed digital data communication and one of them is related to duty cycle correction. In this paper, a low-area duty cycle correction circuit for a voltage-controlled ring generator is proposed. The duty cycle correction circuit is a circuit that corrects the duty cycle using a 180 degree phase difference of a voltage controlled ring oscillator. The proposed low-area duty cycle circuit changes a conventional flip-flop to a true single phase clocking (TSPC) flip-flop And a low-area high-performance circuit is realized. By using TSPC flip-flop instead of general flip-flop, it is possible to realize low-area circuit compared to existing circuit, and it is expected to be used for high-performance circuit for low-power because it is easy to operate at high speed.

• Journal of the Semiconductor & Display Technology
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• v.22 no.1
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• pp.94-98
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• 2023

In the case of high-speed data transmission on high multilayer boards, signal coherence is a problem, especially due to the via hole, and a solution to improve return loss or insertion loss by applying a back drill to the via hole is being proposed. In this paper, Near-Field Electromagnetic measurements were made on a high multilayer board to determine how the presence or absence of back drill affects signal consistency. For this purpose, we used a signal generator, spectrum analyzer, and EMC scanner on a test board to determine if it is possible to distinguish between areas with and without back drill in the via holes of the stubs on the board. Also, we analyzed the measured value of S11, S21 and EMC etc. for how much it improves the signal attenuation of the stub with back drill. Through this, we knew that less electromagnetic waves are generated the stub via with back drill. At future research, we will analyze how much it improves the signal loss and electromagnetic waves due to the depth of back drill.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.609-617
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• 2014

Even though the variable pitch control of a wind turbine blade is known as an effective component for power control over the rated wind speed, it has limited applicability to small wind turbines because of its relatively high cost on the price of small wind turbine. Instead, stall control is generally applied in the blade design without any additional cost. However, stall delay can frequently be caused by high turbulence around the turbine blade, and it can produce control failures through excessive rotational speed and overpowering the electrical generator. Therefore, a passive pitch control module should be considered, where the pitch moves with the aerodynamic forces of the blade and returns by the elastic restoring force. In this study, a method to calculate the pitch moment, torque, and thrust based on the lift and drag of the rotating blade wing was demonstrated, and several effective wing shapes were reviewed based on these forces. Their characteristics will be estimated with variable wind speed and be utilized as basic data for the design of the passive pitch control module.

• KIEAE Journal
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• v.15 no.1
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• pp.155-160
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• 2015

The annual average of energy sources is continuously increasing at a rate of 5.8%, and particularly, the power generation proportion of new/renewable energy is increasing significantly. Furthermore, South Korea has established a national energy master plan for 2008-2030 and is aiming at obtaining approximately 11% of total energy production from the wind turbine sector. Although offshore wind turbines are similar to wind turbines installed on land, they require materials with excellent dynamic properties and durability to prevent damage due to seawater at the lower parts and connecting parts. The lower parts of wind turbines are submerged in seawater, and the upper and lower parts are connected by filling the connecting part with grout. This paper describes the test results of the process of determining the mix ratios to develop ultra-high grout for offshore wind turbines. There is virtually no relevant technology regarding grout for offshore wind turbines in South Korea that can be referenced for the process of determining the mix ratios. Therefore, tests were conducted for determining compression strength, elastic modulus, flexural strength, density, constructability (floor test), and early strength by referencing a high-performance grout produced in South Korea, and the mixing process for achieving the goal strengths was described using the Korean Industrial Standards (KS) as the reference.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.192-196
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• 2010

Due to a development of a modem technology as Power Line Communication(PLC) over 200 Mbps, the high-speed multi-media data trasmission could be currently possible. The strength of the PLC has no more additional wiring work. PLC has also possible to high quality data transmission with currently electrical cable. It has a various strong point campare with existing wire and wireless communication technologies. In This paper we develop a high quality media transmitter-receiver based on merging the HomePlug AV, which is 200 Mbps class PLC technology and HDMI Interface technology. The video function was used for the VEDEO TEST GENERATOR in order to a property valuation. Smart Live 6 software were used for the assessment of audio property. As the result of measurement of the HD class images by capturing from the receiver of the PLC, the quality of images couldn't be confirm any deterioration, which has compared with original reflections. In case of audio part as the result of confirmation of the Phase, Magnitude, it has been confirmed that over 90% of nomal transmition and receiving of acoustic signal. It can be possible to have HD class Media service through the PLC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.11
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• pp.1304-1310
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• 2010

This study is to design FMCW radar transceiver of K-band which is used to detect and track approaching high speed targets with low altitude. The transmitter needs high output power due to small RCS targets and wide beamwidth of transmit antenna. Multi-channel receivers are required to detect and track targets by interferometer method. Transmitter consists of high power amplifier, waveguide switch, and frequency up-converter. Receiver is composed of five channel receivers, up and down converters, X-band local oscillator and waveform generator. Before manufacturing it, the proposed architecture of transceiver is proved by modeling and simulation using several parameters. Then, it is manufactured by using industrial RF components. The performance parameters are measured through experiment. In the experiment, transmitting power and receiver gain were measured with 39.64 dBm and 29.1 dB, respectively. All other parameters in the specification were satisfied as well.

• Textile Coloration and Finishing
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• v.12 no.3
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• pp.207-217
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• 2000

A new, high-efficiency ultrasonic fabric washing machine was developed to be an energy-efficient washing machine and to enhance fabric washing quality in washing processes of the dyeing and finishing process in the textile industry. This system is composed of ultrasonic wave generator, air blowing nozzle, torque motor for fabric tension control, and enclosed washing bath, multi-tube type exchanger, noiseless heater, air cylinder, expander roller, mangle upper and lower rollers, bend bar, dancer, shower spray nozzle, and solenoid valve, and so on. These elements are synergised for fabric washing. One of the very important principles is the low tension fabric running system. For an efficient washing effect, a counter flow system is also adopted. The new system also adopts the dancer and torque motor to control fabric tension and prevent fabric creasing. Shower spray nozzle, counter flow and overflow apparatus, and air-blowing apparatus are adopted to enhance the fabric washing effect. In this study, peach yoryu, exter, and moss crepe fabrics were washed by the general and ultrasonic washing systems under different conditions respectively. The washing efficiency was affected by the fabric running speed and characteristics of fabrics. Size content after washing increased with increasing the fabric running speed. The values in the general washing system were higher than those of the ultrasonic washing system. The changes of conductivity in the ultrasonic and the cooling bath were affected by the running time under the ultrasonic generating. The values of conductivity decreased as the experimental time passed.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1008-1010
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• 2005

In the examination of steam generator(SG) tube in nuclear power plant, eddy current testing probes play an important role in detecting the defects. Bobbin probe and MRPC probe is usually used for the inspection of SG tube. Bobbin probe is good at high speed inspection, but ability of detection of circumferential defect is very weak. On the contrary MRPC probe, which moves for inspection in the direction of axial and circumferential simultaneously, has very slow inspection speed, but it has excellent detection capability for small cracks, which is hardly detected by bobbin probe. In this paper, for the accurate analysis of experimental ECT signals, construction of MRPC probe signals database according to the variation of defect size is the main purpose. Using 3-D finite element method, ECT signals are analyzed, and signals analysis add according to frequency ingredient. The results, which are analysis and characteristics ion of electromagnetism simulation signals, is databased.

• Solar Energy
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• v.20 no.1
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• pp.1-9
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• 2000

Wind turbine system converts wind energy into electric energy. Since the velocity of wind is random in nature, control of the angular velocity of the blade is necessary in order to generate high quality electric power. The control of a blade can be divided into a stall regulation and a pitch control types. The stall regulation type which is based on the characteristics of an aerodynamic stall of the blades is simple and cheap, but it suffers from fluctuation of the resulting power. Or the contrary, pitch control type is based on the fact that the torque of the blade can be changed by varying the pitch angle of the blade. It is mechanically and mathematically complicated, but the control performance is better than that of the stall regulation type. This paper suggests a method of denying a mathematical modeling of the wind turbine system, and develops a speed control algorithm by pitch control. The validity of the algorithm is demonstrated with the results produced through sets of simulation.