• 제목/요약/키워드: POSTECH

검색결과 1,875건 처리시간 0.033초

재귀 베이시안 추정을 이용한 회전기기 진단 (Diagnostics of Rotating Machinery using Recursive Bayesian Estimation)

  • Oh, Joon-Seok;Sohn, Seok-Man;Kim, Hee-Soo;Lee, Seung-Cheol;Bae, Yong-Chae
    • KEPCO Journal on Electric Power and Energy
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    • 제6권1호
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    • pp.49-52
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    • 2020
  • Since power plant is an important system to provide electricity, it is necessary to monitor it in order to operate safely. Much information related with machine diagnosis exists in written form instead of digital data. So, it causes difficulties of analyzing and finding solutions. Rulebased expert system can provide flexible and effective solutions to users. In this paper, Recursive Bayesian Estimation is applied in order to increase accuracy of solutions.

Risk 정보 전송을 위한 Push Notification 구조 (A Push Notification Structure for Trnsmitting Risk Information)

  • 김경준;김철원;김진만
    • 한국정보통신학회:학술대회논문집
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    • 한국정보통신학회 2015년도 추계학술대회
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    • pp.1033-1034
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    • 2015
  • 현재 인터넷의 전송방식인 기존 Push 메시지 전송방식은 한계를 가지고 있다. 따라서, 본 논문에서는 다양한 형태의 재난 Risk정보들을 원격지에 빠르게 전송하기 위해 QoS(Quality of Service)를 고려한 Push Notification 구조를 제안한다. 제안한 구조를 통해 현재의 이질적인 시스템을 수용하면서, 다양한 기기에서 인터넷 서비스를 제공한다.

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$Zn(HPB)_2$를 블루 발광층으로 이용한 White OLED의 색순도 특성 (Properties of color purity as white OLED based on $Zn(HPB)_2$ as blue emitting layer)

  • 김동은;김병상;김두석;이범종;권영수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년도 추계학술대회 논문집 전기물성,응용부문
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    • pp.89-90
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    • 2006
  • We synthesized emissive materiaJs, nameJy $Zn(HPB)_2$. The fundamentaJ structures of the OLEDs were ITO / NPB (40 nm) $Zn(HPB)_2$ (40 nm) / $Alq_3$:DCJTB (20, 30, or 40 nm) / LiF / AI. We varied the thickness of $Alq_3$:DCJTB from 20 nm to 40nm. We measured current density-voJtage and luminance-voJtage characteristics at room temperature. When the thickness of the Alq3:DCJTB layer was 40 nm, white emission is achieved. The CIE coordinates are (0.32, 0.33) at an applied voltage of 14V.

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Noncoherent Unitary Space-Time Modulated DSSS Systems in Multipath Channels

  • Cheun, Kyung-Whoon;Kim, Jeong-Chang;Kim, You-Han;Choi, Soong-Yoon
    • Journal of Communications and Networks
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    • 제14권2호
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    • pp.206-212
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    • 2012
  • In this paper, in order to effectively apply unitary space-time modulation to the direct-sequence spread-spectrum multiple-access (DSSS-MA) networks, we propose a low-rate, noncoherent, unitary, and space-time modulated DSSS system supporting any number of transmit antennas based on Walsh matrices. The proposed scheme simultaneously performs bandwidth spreading and space-time coding and outperforms those using high-rate, conventional unitary space-time constellations. Furthermore, the proposed scheme allows for a simple detector structure based on fast Walsh transforms.

수중 음향센서용 전력증폭기를 위한 멀티레벨 컨버터의 제어 알고리즘 (Control Algorithm of Multilevel Converter for Power Amplifier of Underwater Acoustic Sensor)

  • 심재혁;김인동;노의철;문원규;김원호
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2013년도 전력전자학술대회 논문집
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    • pp.399-400
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    • 2013
  • 본 논문에서는 수중음향 센서를 위한 전력증폭기용 전원회로로 멀티레벨 가변전압출력 AC-DC 컨버터의 제어 알고리즘을 제안한다. 제안하는 제어 알고리즘은 최종 출력으로 5-레벨 가변전압을 얻기 위한 2대의 Flying capacitor 3-level converter의 전력 균등분담 제어를 위해 사용되며, 플라잉 커패시터의 전압 밸런싱 제어를 위해 사용된다. 본 논문에서 제안하는 제어 알고리즘은 수중음향 센서를 위한 전력증폭기용 전원회로에서 유용하게 사용될 것으로 예상한다.

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유량 제어을 위한 PLC 시뮬레이터 구성 (The construction of a PLC simulator for level control)

  • 이기범;윤우식;정희돈;이진수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 D
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    • pp.2605-2607
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    • 2000
  • This paper represents the construction of a PLC simulator for the level control of water and the speed control of the water cask. The level and speed processes are automatically operated by the PLC. The simulator system consists of PLC, program loader and control penal. The digital input and output units make the valves of the water cask the On or Off state. The analog input and output units control the level of water and the speed of the water cask. A LD program is used in the control language of PLC.

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PLC 프로그래밍을 위한 가상 플랜트 시뮬레이터 구현 (The implementation of a virtual Plant simulator for the PLC Programming)

  • 이기범;김세연;이진수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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    • pp.475-477
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    • 1998
  • In this paper, the implementation of a virtual Plant simulator for the PLC programming is presented. A virtual plant simulator that replaces function of transducers (e.g. pumps and valves) consists of a personal computer and a PLC(Programmable logic controller). Input/output conponents are edited on the monitor and are operated as the field transducers. The timing process for input/output components is analyzed. The data flow between a PLC system and a virtual plant simulator is carried out.

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Single Organic Molecules Designed as Nanoscale Connectors: Fullerene Isoxazoline Derivatives

  • Lee, Han-Myong;Lee, Chang-Hoon;Cho, Min-Sil;Hwang, Yong-Gyoo;Lee, Kee-Hag
    • Bulletin of the Korean Chemical Society
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    • 제25권12호
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    • pp.1850-1854
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    • 2004
  • Recently a fullerene isoxazoline was reported as an example for nanoscale connectors in molecular electronic devices. The construction of nanoscale devices is a potentially important area of technology. By using the semiempirical PM3 calculation, we optimized the structures for two fullerene isoxazoline derivatives and thirteen regioisomers of the second addition of a nitride oxide to a fullerene isoxazoline derivative. Our results suggest that fullerene isoxazoline derivatives could be used as nanoscale connectors with the possibility of attaching of spacer units in a specific angle arrangement.

Dependency Structure Applied to Language Modeling for Information Retrieval

  • Lee, Chang-Ki;Lee, Gary Geun-Bae;Jang, Myung-Gil
    • ETRI Journal
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    • 제28권3호
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    • pp.337-346
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    • 2006
  • In this paper, we propose a new language model, namely, a dependency structure language model, for information retrieval to compensate for the weaknesses of unigram and bigram language models. The dependency structure language model is based on the first-order dependency model and the dependency parse tree generated by a linguistic parser. So, long-distance dependencies can be naturally captured by the dependency structure language model. We carried out extensive experiments to verify the proposed model, where the dependency structure model gives a better performance than recently proposed language models and the Okapi BM25 method, and the dependency structure is more effective than unigram and bigram in language modeling for information retrieval.

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An Efficient Representation of Edge Shapes in Topological Maps

  • Doh, Nakju Lett;Chung, Wan-Kyun
    • ETRI Journal
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    • 제29권5호
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    • pp.655-666
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    • 2007
  • There are nodes and edges in a topological map. Node data has been used as a main source of information for the localization of mobile robots. In contrast, edge data is regarded as a minor source of information, and it has been used in an intuitive and heuristic way. However, edge data also can be used as a good source of information and provide a way to use edge data efficiently. For that purpose, we define a data format which describes the shape of an edge. This format is called local generalized Voronoi graph's angle (LGA). However, the LGA is constituted of too many samples; therefore, real time localization cannot be performed. To reduce the number of samples, we propose a compression method which utilizes wavelet transformation. This method abstracts the LGA by key factors using far fewer samples than the LGA. Experiments show that the LGA accurately describes the shape of the edges and that the key factors preserve most information of the LGA while reducing the number of samples.

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