• Title/Summary/Keyword: 역화

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광대역 가입자망 구성기술 현황

  • 전흥범;이상훈
    • The Magazine of the IEIE
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    • v.22 no.6
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    • pp.71-82
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    • 1995
  • 공중통신망에서 광대역 통신 서비스의 제공을 위해서는 가입자망의 광대역화가 필수적이다. 그러나, 가입자망의 광대역화에는 막대한 양의 투자가 필요하기 때문에 체계적이고 경제적인 지화계획의 수립이 요구된다. 본 고에서는 현재 세계 각국에서 중점적으로 연구되고 있는 광대역 가입자망의 구성 기술에 대하여 살펴 보고, 이에 대한 국제적인 표준화 현황, 그리고 한국의 가입자망 상황과 바람직한 진화 방안에 대하여 검토하여 보겠다.

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Reading 'Little Manila' along Daehangno : Exploring the Conceptualization of Transnational Spaces (대학로 '리틀마닐라' 읽기 : 초국가적 공간의 성격 규명을 위한 탐색)

  • Jung, Hun-Joo
    • Journal of the Korean association of regional geographers
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    • v.16 no.3
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    • pp.295-314
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    • 2010
  • The paper attempts to balance the discourses of transnational spaces that have focused on de-territorialization, by emphasizing that transnational spaces are maintained also through re-territorialization. Reviewing the literature of transnational social fields, translocality, multicultural spaces and transnational places, I aim to show the way the main issues from the literature help understand an actually existing transnational space, Little Mania in Daehangno, Seoul. I specifically address the dialectic relation between de-territorialization and re-territorialization, multi-scalar networks, and hybridity of multicultural spaces in interpreting the weekend enclave of Filipinos in Seoul. I argues that Little Manila is a grounded translocality operating through multi-scaled networks of various actors. Furthermore, it is not a unified space where one dominant Filipino identity stands out. Different Filipinos and Filipinas constitute the space imagining different homes. It is also a multicultural space open to other minorities, which suggests the possibility of alternative spatial politics based on co-presence of different 'Others'.

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Document Reranking Model Using Clusters (문서 클러스터를 이용한 재순위화 모델)

  • Lee, Kyung-Soon;Park, Young-Chan;Choi, Key-Sun
    • Annual Conference on Human and Language Technology
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    • 1998.10c
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    • pp.81-87
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    • 1998
  • 본 연구에서는 정보검색시스템의 모델로 문서 클러스터를 이용한 재순위화 모델을 제시한다. 이 방법은 검색단계와 분석단계로 이루어지는데, 검색단계에서는 역화일기법을 이용해서 질의어를 포함하는 문서들을 검색하여 질의어-문서 유사도에 따라 순위를 결정한다. 분석단계에서는 이미 구축된 문서 클러스터를 이용해서 검색되어진 문서들의 분석을 통해 질의어-클러스터 유사도를 계산한다. 질의어-문서 유사도와 질의어-클러스터 유사도를 결합하고, 이 유사도에 기반해서 문서들을 재순위화한다. 이때 이용하는 클러스터는 정적 클러스터이고, 질의어에 따라 서로 다른 클러스터를 생성하는 동적인 뷰를 제공한다. 재순위화 모델은 역화일 기법과 클러스터 분석기법이 가지는 장점을 결합하여 질의어 뿐만 아니라 문서에 포함된 모든 단어들을 분석함으로써 문서의 문맥을 고려할 수 있다. 제안하는 모델은 역화일 기법을 이용한 검색 결과에 비해서 우수한 성능 향상을 나타내고 있다.

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A Study on Enhancement of Combustion Performance by Dilution of Hydrogen in Heavy-Duty Hydrogen Engine (수소기관의 수소연료의 희석에 의한 역화억제효과에 관한 연구)

  • KIM, S.Y.;KIM, Y.Y.;Kim, Y.T.;LEE, JONG T.
    • Transactions of the Korean hydrogen and new energy society
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    • v.15 no.4
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    • pp.348-354
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    • 2004
  • Hydrogen gas has several merits such as lower ignition energy, wide flammability and shorter quenching distance. It leads to high thermal efficiency but backfire occurrence. In this study, feasibility of expansion of BFL(Back-Fire Limit) equivalence ratio and combustion characteristics by a dilution of hydrogen fuel are experimently examined by using experimental heavy duty single cylinder hydrogen fueled engine. As results, it is found that BFL equivalence ratio is expanded to rich range and torque is increased.

Extension of Backfire Limited Equivalence Ratio in Hydrogen Engine by Using Multi Point Ignition Method (다점점화에 의한 수소기관의 역화발생 억제효과에 관한 검토)

  • Kim, Y.Y.;Lee, C.W.;Lee, Jongtai
    • Transactions of the Korean hydrogen and new energy society
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    • v.14 no.2
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    • pp.131-137
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    • 2003
  • Backfire occurrence must be controlled for the practical use of hydrogen fueled engine. It was found from preceeding studies that crevice volume around piston rings could effect a backfire occurrence. In this study, a possible countermeasure to backfire occurrence was evaluated by using multi point ignition method around piston ring. The results showed that backfire limited equivalence ratio was increased by a little due to a enhancing effect of mixture combustion around piston crevice volume.

소형 광대역 안테나

  • 임성빈;박용욱;최학근
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.2 s.54
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    • pp.3-12
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    • 2005
  • 안테나를 소형화하면 안테나의 복사효율이 저하되고, 대역폭이 좁아지며, 안테나 이득이 작아진다는 사실은 잘 알려져 있다. 그러나 이런 전기적 성능저하에도 불구하고 최근 무선통신 시스템의 소형화와 고성능화에 따라 안테나의 소형화 및 광대역화가 끊임없이 요구되고 있다. 여기서는 이런 요구에 부응하기 위하여 소형 안테나의 종류와 소형화시 나타나는 문제점을 확인하고 선형 안테나와 평판 안테나를 중심으로 소형화 및 광대역화 기법을 소개하고 고찰하였다.

A Study on ADSL transmission speed enhancement in High-speed Internet (초고속 인터넷을 위한 ADSL 전송속도 향상연구)

  • 김홍모;고남영
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.4 no.5
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    • pp.1077-1083
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    • 2000
  • With rising demand of Internet Service, the existing communication for users (aced the restricted capability and speed, and also failed to satisfy consumer's desire for providing service-quality to them. It can be accomplished the broad-band on subscribe-line to offer various multimedia service to subscriber. But it takes a lot of times and costs. Consequently, it stands out the most economic subscribe-line for acheving a broadband scheme that new transmission technology can be realized the high-speed data communication as the present telephone-line and telephone by the general public of FTTH(Fiber To The Home). As using the pseudo line, this paper have the result that the mesured speed was improved by connecting a variable resistor on the line.

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Characteristics of Performance and Back-Fire for External Mixture Hydrogen Fueled Engine without Valve Overlap Period (밸브 오버랩 기간이 없는 흡기관 분사식 수소기관의 성능 및 역화특성)

  • Lee, K.J.;Kang, J.K.;Cong, Huynh Thanh;Noh, K.C.;Lee, J.T.
    • Transactions of the Korean hydrogen and new energy society
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    • v.18 no.4
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    • pp.374-381
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    • 2007
  • In order to verify the feasibility of expansion of back-fire limit equivalence ratio in the hydrogen-fueled engine with external mixture, the characteristics of performance and combustion are experimentally analyzed with change of intake/exhaust valve timings under the fixed valve overlap period of $0^{\circ}$ CA(non-valve overlap period). These characteristics are also tested for the change of exhaust valve closing timing while intake valve opening timing is fixed to clear the main cause of back-fire occurrence. As the results, the less valve overlap period center is retarded, the more back-fire limit equivalence ratio increases and back-fire does not occurred after TDC. In addition, it was shown that the control of back-fire is dependent on intake valve opening timing than valve overlap period.