• Title/Summary/Keyword: Mica

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Assessment of Insulation Condition in Gas Turbine Generator Stator Windings (가스터빈 발전기 고정자 권선의 절연상태 평가)

  • Kim, Hee-Dong;Yang, Gyu-Hyun;Ju, Young-Ho
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.8
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    • pp.1423-1428
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    • 2010
  • The results of off-line and on-line diagnostic tests performed on the stator winding of an air-cooled gas turbine(G/T) generator are reported in this paper. Off-line diagnostic tests included measurements of the ac current, dissipation factor(tan${\delta}$), and partial discharge(PD). Six epoxy-mica capacitors were installed in the three phases of G/T generator for performing on-line diagnostic testing with the turbine generator analyzer(TGA). The TGA showed that the normalized quantity number(NQN) and the PD magnitude($Q_m$) were high in phase A of the stator winding. Internal discharges were generated in phases B and C, and slot discharge occurred in phase A. According to the trend analyses of the NQN and $Q_m$ values available for insulation condition assessment for G/T generator stator windings, it was concluded that phases B and C were in good condition, whereas phase A has been significantly deteriorated.

Characteristics of Insulation Aging in 4.16kV Motor Stator Windings (4.16kV 전동기 고정자 권선의 절연열화 특성)

  • Kim, Hee-Dong;Kong, Tae-Sik
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1381_1382
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    • 2009
  • Nondestructive tests were performed on two 4.16kV motors. Epoxy-mica coupler(80pF) was connected to 4.16 kV motor stator windings. The voltage applied to the stator windings was 2.4 kV, 3.0kV, 3.5kV and 4.16kV, respectively. Digital partial discharge detector(PDD) and turbine generator analyzer(TGA) were used to measure partial discharge(PD) activity. TGA summarizes each plot with two quantities such as the normalized quantity number(NQN) and the peak PD magnitude(Qm). The PD levels in pC were measured with PDD. PD patterns of stator windings were indicated the internal discharge. PD patterns are consistent with the result of measurement using PDD and TGA.

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A study on boron removal for seawater desalination using the combination process of mineral cluster and RO membrane system

  • Cho, Bong-Yeon;Kim, Hye-Won;Shin, Yee-Sook
    • Environmental Engineering Research
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    • v.20 no.3
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    • pp.285-289
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    • 2015
  • Complicated and expensive seawater desalination technology is a big challenge in boron removal process. Conventional seawater desalination process of coagulation utilized for pre-treatment is difficult to remove boron. Boron can be removed more effectively in Reverse Osmosis (RO) process than any other processes. In this study, a coagulant with the name Mineral Cluster was examined its boron removal ability. Boron removal efficiency of Mineral Cluster depended on pH value and Mineral Cluster dosage. Desalination process combines the pre-treatment process with Mineral cluster diluted at the ratio of 1:2500 and the RO membrane process. The original sea water could be desalinated to drinking water quality, 1 mg/L, without any pH adjustments. Therefore, if the Mineral cluster is added without any other chemicals for adjusting pH, the desalination process would be much safer, efficient and economical.

SPEED-MAC: Speedy and Energy Efficient Data Delivery MAC Protocol for Wireless Sensor Network (SPEED-MAC: 무선 센서 네트워크 환경에서 전송성능을 향상시키기 위한 에너지 효율적인 MAC 프로토콜)

  • Lee, Hyun-Jun;Lee, Sang-Hoon;Choi, Lynn
    • Proceedings of the Korean Information Science Society Conference
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    • 2007.10d
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    • pp.597-601
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    • 2007
  • 본 논문에서는 휴면 지연에 의한 전송지연을 줄이는 효과적인 방법으로 staggered schedule 방식에 기반하여 동작하는 SPEED-MAC 프로토콜을 제안하고자 한다. SPEED-MAC은 이벤트 발생에 따른 정보를 발생사실과 세부정보로 나누어 각각 이벤트 공지 구간과 데이터 전송 구간에 싱크 노드로 전송함으로써 이벤트 발생 사실을 싱크 노드에게 최단시간에 전송할 수 있다. 또한 제어 패킷의 오버헤드를 줄이기 위해 이벤트 공지 구간에서 signal 패킷을 사용함으로써 데이터 패킷을 전송할 때 발생 가능한 충돌을 예측하였고 제어 패킷을 동적으로 사용하여 노드의 에너지 효율성을 추가로 개선할 수 있게 되었다. 본 논문에서는 SPEED-MAC을 MICA MOTE에서 구현하였으며 기존의 MAC 프로토콜에 비하여 메시지 전송 지연시간을 대폭 단축시킬 수 있었으며 또한 저 전력을 구현할 수 있는 것을 확인하였다.

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A Development of CCTV Control System Based on Wireless Sensor Network (무선 센서 네트워크 기반 CCTV 제어 시스템 연구)

  • Cho, Soo-Hyung;Kim, Dae-Hwan
    • 한국정보통신설비학회:학술대회논문집
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    • 2009.08a
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    • pp.219-220
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    • 2009
  • Many surveillance cameras used in security system are controlled with RS-485 communication protocol. In this situation, if RS-485 connection can be replaced with wireless connection using sensor network technology, an installation will become ease because of no wired connection and also a deployment of cameras will become free. This paper explains about the design of wireless sensor node and the necessary implementation for an operation, which can be replacing RS-485 connection for the development of CCTV control system based on wireless sensor network. The hardware platform of sensor node was designed based on MicaZ and the software was developed based on TinyOS. To control surveillance cameras deployed on wide area, the supporting of multi-hop also was implemented. With the result of experiment deploying on real environment, it was revealed that the controller could control cameras quickly with wireless.

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Characteristics of Capacitive Coupler for Partial Discharge Measurement in 6.6kV Rotating Machines (6.6kV 회전기 부분방전 측정용 Capacitive Coupler 특성)

  • Kang, Dong-Sik;Yoon, Dae-Hee;Kim, Yong-Joo;Yun, Yung-Ho;Lee, Jung-Jun;Song, Sang-Ock
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1619-1622
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    • 2001
  • Recently many researches on the diagnosis of stator winding insulation for large rotating machines have been developed sine the 1970s. Capacitive coupler has been the most widely used sensor for on-line partial discharge(PD) in rotating machines. The 105 [pF] ceramic coupler(CC) has been developed to continuously measure the PD activity in operating motor stator windings. This paper presents frequency characteristics and laboratory test to compare traditional 80 [pF] epoxy-mica coupler(EMC) and 105 [pF] CC for PD measurement in 6.6 [kV] stator windings.

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Insulation Aging Properties of Off-Line and On-Line High Voltage Motor Stator (정지중 및 운전중 고압전동기 고정자 권선의 절연열화 특성)

  • Kim, Hee-Dong;Lee, Young-Jun;Ju, Young-Ho
    • Proceedings of the KIEE Conference
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    • 2001.07c
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    • pp.1694-1696
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    • 2001
  • Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in six 6.6kV motors. These tests were conducted using a conventional partial discharge detector (PDD), turbine generator analyzer(TGA) and partial discharge analyzer(PDA). Off-line PD measurements were performed on six 6.6kV motors. PD magnitudes ranged from 740 pC to 5,100 pC at the normal line-to-ground voltage. Six 6.6kV motors have been equipped with eighteen 80pF epoxy-mica couplers(one per phase) on the motor terminal boxs. The PD pulse from sensors were measured with the TGA and PDA instruments on a normally operating motors. The PDD, TGA and PDA test results showed that internal discharge was detected in voids of the groundwall insulation.

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A Study on the Utilization of Yun Chun Andalusite as a Raw Material of High Alumina Refractories (I) -On the Occurrence and General Characteristics- (고 알루미나질 내화물 원료로서 연천산 홍주석의 이용에 관한 연구 (I) -홍주석의 산출상태 및 일반적특성-)

  • Ahn, Young-Pil;Choi, Long
    • Journal of the Korean Ceramic Society
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    • v.11 no.1
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    • pp.19-22
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    • 1974
  • The andalusite that can be found in mica shist near YunChun deposits were studied by means of an optical microscope, X-ray diffraction, thermal analysis of DTA and TGA, chemical analysis and refractoriness test to find out an appropriate method of concentration and purification for the utilization as a raw material of high alumina refractories, with the results: 1. The andalusite are has chiefly contained andalusite, muscovite and biotitei in addition to small amounts of chlorite, kyanite, disapore, quartz, alumandite adn pyrite, which vary from sample to sample. 2. Most of andalusite have occurred as light-red colored columns which are estimated to be an average of 4 by 0.5m/m in length. 3. Samples of andalusite which were dressed by cobbing and hand picking in the deposits have contained an average of 42% andalusite.

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Damage Analysis of High Voltage Motor for Intake Pump (취수 펌프용 고압전동기(6.6 kV, 3,800 kW)의 소손원인 분석)

  • Oh, Min-Hwan;Lee, Eun-Chun;Hong, Sung-Taek;Lee, Sang-Gun
    • Proceedings of the KIEE Conference
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    • 1999.07c
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    • pp.1324-1326
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    • 1999
  • This paper demonstrates the insulation-destruction of high-voltage-motors for intake pump. To analyze the causes of damage in motors, electrical, mechanical and environmental fiery-development were investigated. The insulation-destruction of high-voltage-motors are generally due to the fiery-stress by void where composite materials such as mica/epoxy are used. But this paper shows that electrical and mechanical stresses can be the main reason of the damage, too.

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A Environment Data Monitoring System using Wireless Sensor (무선 센서를 이용한 환경정보 모니터링 시스템)

  • Seong, Chang-Gyu;Rhyu, Keel-Soo;Park, Jong-Il;Weon, La-Kyoung;Kim, Tai-Jin
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2006.06a
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    • pp.89-90
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    • 2006
  • 무선센서 네트워크 기술은 최근 주목 받고 있는 유비쿼터스 컴퓨팅의 핵심 분야로서, 그 활용도가 다양해서 이와 관련된 많은 연구 개발이 이루어지고 있다. 본 논문에서는 무선 센서 네트워크 기술을 여러 응용 분야에 활용될 수 있는 환경 정보 모니터링 시스템에 적용시켜 보았다. 센서 노드로써 MicaZ와 그 운영체제인 TinyOS를 이용하여 온도, 조도, 습도, 가속도, 그리고 위치 등의 사용자 환경 정보를 탐지하고 처리하는 시스템을 구현하여 사용자가 원하는 환경의 조건을 유지하는데 이용될 수 있도록 하였다.

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