• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.192-199
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• 2016

With changes in insulated defects, the environment, and so on, new partial discharge (PD) data are highly different from the original samples. It leads to a decrease in on-line recognition rate. The UHF signal and pulse current signal of four kinds of typical artificial defect models in gas insulated switchgear (GIS) are obtained simultaneously by experiment. The relationship map of ultra-high frequency (UHF) cumulative energy and its corresponding apparent discharge of four kinds of typical artificial defect models are plotted. UHF cumulative energy and its corresponding apparent discharge are used as inputs. The support vector machine (SVM) incremental method is constructed. Examples show that the PD SVM incremental method based on simulated annealing (SA) effectively speeds up the data update rate and improves the adaptability of the classifier compared with the original method, in that the total sample is constituted by the old and new data. The PD SVM incremental method is a better pattern recognition technology for PD on-line monitoring.

• Carbon letters
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• v.26
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• pp.61-65
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• 2018

Comprehensive calculations of the Rh decoration effect on zigzag CNTs with n ranging from 7 to 12 were conducted in this work to understand the effect of Rh doping on geometric structures and electronic behaviors upon metallic and semiconducting CNTs. The obtained results indicated that Rh dopant not only contributes to the deformation of C-C bonds on the sidewall of CNTs, but also transforms the electron distribution of related complexes, thereby leading to a remarkable increase of the conductivity of pure CNTs given the emerged novel state within the energy gap for metallic CNTs and the narrowed energy gap for semiconducting CNTs. Our calculations will be meaningful for exploiting novel CNT-based materials with better sensitivity to electrons and higher electrical conductivity compared with pure CNTs.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.107.2-107
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• 2001

We propose portable equipment that monitors a current and potential on high-potential power transmission lines. In the equipment, a current and voltage sensor are attached to a hollow insulator that supports a power transmission line: A current on a power line is detected by an air-core solenoidal coil clamped to the line and the detected current signal is transmitted to the ground station by using optical data link, A potential on a power transmission line is detected by a high resistance element, zinc oxide (ZnO) that acts as a potential divider between the power line and the ground. The equipment does not require high potential insulators and magnetic cores which. This leads to the following advantages of the equipment: (a) It is easily installed owing to its small size and its simple structure; (b) It operates in low ...

• ETRI Journal
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• v.31 no.6
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• pp.806-808
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• 2009

A new computationally efficient algorithm-based propagator method for two-dimensional (2-D) direction-of-arrival (DOA) estimation is proposed, which uses two parallel uniform linear arrays. The algorithm takes advantage of the special structure of the array which enables 2-D DOA estimation without pair matching. Simulation results show that the proposed algorithm achieves very accurate estimation at a computational cost 4 dB lower than that of standard methods.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1759-1764
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• 2015

Glow corona is a kind of streamer-free corona that can suppress upward leaders in transmission lines. Thus, it has good application potential in lightning protection. This paper investigates its corona characteristics. The suppression characteristic of glow corona on streamer is studied in air gap under negative DC voltage by wrapping thin wires on the electrode. The effect of thin wire winding patterns on the gap breakdown voltage is analyzed. Results are considered to be attributed to the inception condition of glow corona. Thus an inception test of glow corona is also conducted, and the inception voltage is obtained. Results show that the inception voltage decreases with short winding pitch. Thus an investigation on the inception of glow corona influenced by thin wire is conducted, and an influential factor is proposed to evaluate the influence. The inception regular of thin wire glow corona presented in this paper has certain reference value for the application of glow corona in transmission lines.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.41-44
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• 2003

We propose portable equipment that monitors current and voltage of high-potential power transmission lines. In the equipment, a current and voltage sensor are attached to an insulator that supports a power transmission line: A clamped to the power line and the detected current signal is transmitted to the ground station by a wireless optical link using transmission line is detected by a high resistance element, zinc oxide (ZnO). That acts as a potential divider between the power line and ground. We make an experimental device for 66kV power line and demonstrate that it can monitor currents proposed equipment is small-sized, light, and inexpensive in comparison with the conventional CT (current transformer) and PT (potential transformer) since it does not require high potential insulators and magnetic cores, further, the equipment is easily installed owing to its small size and its simple structure.

• International journal of advanced smart convergence
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• v.6 no.2
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• pp.51-58
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• 2017

Recently, rapid advances of Ethernet and IP technology have brought many changes in the sound industry. In addition, due to AoIP-based audio transmission technology, various problems of the acoustic system (sound quality deterioration due to long distance transmission, complicated wiring) have improved dramatically. However, when many distributed audio systems are connected with AoIP equipment, if there is a problem in the equipment, it is impossible to operate the connected system. AoIP equipment only can transmit audio signals but cannot adjust the system for acoustic environment. In this paper, AoIP equipment is to be installed with sound equipment on a one-to-one basis, so that various existing problems can be solved and adjustment of sound quality (reverberation, echo, delay and EQ) can be possible by AoIP-based OAC (On-site Audio Center) with built-in DSP function. As a result, uncompressed real-time transmission by distributed transmission/receipt module in OAC (On-site Audio Center) and high quality sound by adjustment of sound quality with built-in DSP can be acquired. It is expected that OAC based sound system will be the industry standard in ubiquitous environment.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.961-968
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• 2016

The non-uniform distribution of contamination on insulator surface has appreciable effects on flashover voltage, and corresponding researches are valuable for the better selection of outdoor insulation. In this paper, two typical types of porcelain and glass insulators which are widely used in ac lines were taken as the research subjects, and their corrections of AC flashover voltage under non-uniform pollution were studied. Besides, their flashover characteristics under different ratio (T/B) of top to bottom surface salt deposit density (SDD) were investigated, including the analysis of flashover voltage, surface pollution layer conductivity and critical leakage current. Test results gave the modified formulas for predicting flashover voltage of the two samples, which can be directly applied in the transmission line design. Also, the analysis delivered that, the basic reason why the flashover voltage increases with the decrease of T/B, is due to the decrease of equivalent surface conductivity of the whole surface and the decrease of critical leakage current. This research will be of certain value in providing references for outdoor insulation selection, as well as in proposing more information for revealing pollution flashover mechanism.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.3
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• pp.68-73
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• 2017

In this study, we design a low-cost test equipment for real-time image observation and transmission/reception distance test using 1m by 1.5m bang-pai kite. The image observation is made by using two servo motors to enable the camera to control the two axis attitude. The image observation equipment is hung on the string of a kite and the test is performed to observe the real time image. The transmission and reception distance test of the wireless RF transceiver module is conducted on the ground and in the air.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.1
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• pp.42-48
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• 2019

Since the underwater telephone was sold in a short time, there are few repair equipments. And equipment is difficult to locate fault. Equipment with transducers must be inspected underwater, and a relative naval vessels is required to perform an operational check. So we developed a tester device to test the transmission card through the spectrum and transmission power, and to develop a device that can conduct operational tests on land. Therefore, the development of the tester reduces the incidence of naval vessels and contributes to the development of domestic underwater communication test equipment.