• KIEE International Transactions on Power Engineering
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• v.5A no.1
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• pp.22-30
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• 2005

The PWM inverter drive may cause an over voltage at the motor terminal, which imposes severe electric stresses on the inter-turn insulation of motor windings. Unlike low-voltage induction motors, high-voltage induction motors have a stator type of form-wound coil for insulation and are insulated to the slot and the coil. So, this paper presents a PWM 3-level inverter, H-Bridge cascaded 7-level inverter and High-voltage induction motor model. It then analyzes the voltage that generates at the input terminal of the high-voltage induction motor fed by each inverter. Also, in order to examine a factor that influences the switching surge voltage, this paper proposes the system equivalent model and performs the case studies using EMTP.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.156-161
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• 2002

This paper proposes an optimized universal motor for improving its performance using the finite element method (FEM) with the (1＋1) Evolution Strategy (ES) algorithm. To do this, various design parameters are modified, such as air gap length, shape of motor slot, pole shoe, pole width, and rotor shaft diameter. Two parameters (arc length of stator pole and thickness of pole shoe) are chosen and optimized using the program, and the optimized model is built and tested with a performance measuring system. The measured values of the model are compared with those of the initial and the optimized model to prove the algorithm. As a result, the final model improves its performance compared with those of the initial model.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.997-1001
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• 2014

In this paper, the interference in small MIMO antennas having two identical composite right- and left-handed transmission-line(CRLH-TL)-based radiating elements is remarkably decreased. The radiating element has the broadside-capacitive coupling as well as slots to be equivalent to the CRLH-TL to prevent the size from increasing for an LTE high band. The suspended line bridging the two radiating elements is optimized to lower the interference between them down to -23 dB, while the overall MIMO antenna system is compact and its antenna performance is acceptable. The design is tested for 2.5 GHz.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.433-436
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• 2008

In this paper, a novel compact broadband dual frequency microstrip antenna is presented. The meander type patch has been designed to have dual resonant frequencies, and the ground with slot was employed to expand the bandwidth in WCDMA band. The simulated results were obtained using HFSS, and the measurement on the proposed antenna was conducted in an anechoic chamber equipped with a network analyzer and a far field measurement system. As a result, measured maximum gain of antenna is 2.07$\sim$2.87 dBi in the GSM band and 3.91$\sim$5.61 dBi in the WCDMA band.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.500-501
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• 2007

The method of maintenance in railway is going to be changed to improve reliability on traction equipment. Partial discharge (PD) tests are useful to evaluate the insulation condition of stator winding. This paper describes the use of PD tests with 5 model coils which have the defects such as internal, slot discharge. The PD tests are performed with epoxy-mica coupler 500 pF at various AC voltages. The result of test shows PD pattern can correlate with the species of defects on 5 model coils.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.568-569
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• 2005

한빛 자기거울 장치는 고온 플리즈마 물성을 연구하기 위한 장치로서 플러즈마 밀도 형성을 위한 slot 형 안테나 고주파 가열 시스템이 중앙 진공용기에 설치되어 있다. 본 연구에서는 이러한 고주파 전송선로, 임피던스 정합 network. 장치 임피던스를 포함하는 한빛 장치의 고주파 가열 시스템에 대하여 기존에 정립된 고주파 가열 이론[1]을 기반으로 하여 이론적인 해석만으로 구성된 회로모델을 완성하였다. 임피던스 정합 소자 값들은 임피던스 정합 조건으로 결정함으로써 다양한 장치 및 플라즈마 변수들의 함수로 표현하여 그 의존성을 조사하였다.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.604-608
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• 1999

Semiconductor industry requires the development of new technology such as 300 mm technology, suitable for manufacturing the next generation dervices. A promising process for realizing 300 mm technology can be achieved by using enlarged microwave plasma chemical vapor deposition (MWCVD) technology. In this work, we used radial line slot antenna for enlarging microwave plasma area, and carried ut the deposition of polysilicon films using enlarged MWCVD for the first time in Korea. The results was as follows. Deposited polysilicon films showed various degrees of crystallinity as well as epitaxy to silicon substrates even at low temperature of $300^{\circ}C$. Deposition rates also controled crystallization behavior and slo deposition rates showed very high crystallinity. It could be said that enlarged MWCVD system and technology was worth to get attraction as one os future technologies for 1 G DRAM era.

• Proceedings of the KSR Conference
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• 1998.11a
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• pp.194-201
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• 1998

It is extremely necessary to use such a secure way to transmit information to a train, which is needed for operating a train. In our system, The information including the allowable velocity of the train, train existence in current area, and other data necessary for operating train, is transmitted in the form of FM signal. Received by the receiver located on train, the signal is filtered, demodulated and analyzed to extract the original information. The analysis of the demodulated signal is done through FFT algorithm using sliding slot. These all are processed digitally by hardware which is implemented by 32bit DSP. The experiments show the validity of the algorithm we presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.152-153
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• 2014

This paper proposes a new dynamic bandwidth allocation algorithm for an XG-PON (10-Gbps-capable passive optical network) system in which an ONU (optical network unit) does not explicitly send its request to an OLT (optical line termination). To estimate the request of the ONU, the OLT monitors the upstream bandwidth usage of the ONU and periodically allocates a probe slot to the ONU.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.195-196
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• 2016

In the maritime mobile radiocommunication service, AIS(Automatic Identification System) devices are most widely using for the exchange of ship's navigational information. The AIS time slot usage increases due to increasing number of ships installed with AIS, and thus the reception rate of AIS data decrease. In order to mitigate this problem, international organizations recommend a sectorised receiving technique using directional antenna. This paper analyzed the sectorised receiving effectiveness of AIS data using Yaga antenna.