• 제목/요약/키워드: RHA

검색결과 684건 처리시간 0.028초

디젤기관의 분사밸브를 위한 고속 솔레노이드의 성능에 관한 연구 (A Study of Performance Test of High Speed Solenoid for Fuel Injector in Diesel Engine)

  • 조규학;라진홍;안수길
    • 동력기계공학회지
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    • 제5권3호
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    • pp.11-16
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    • 2001
  • In the DI diesel engine of passenger cars, common rail injection system have been used to improve the engine performance and reduce the exhaust emission by controlling injection timing, injection pattern, and injection duration. In case that common rail injection system is applied to high speed DI diesel engine, it is necessary to have high response and good repetition characteristics. These characteristics of injector depend on the characteristics of solenoid. Thus, to apply the common rail injection system in the high speed diesel engine, we had designed and made a multi-pole solenoid, and carried out repetition, response test to compare the multi-pole solenoid with the gasoline Injector solenoid. The result shows that repetition and response characteristics of multi-pole solenoid have better characteristics than the gasoline injector solenoid.

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COII Sequence-based Study for Population Genetic Variation of a Ground Beetle, Scarites aterrimus (Coleoptera : Carabidae)

  • Wang, Ah-Rha;Kim, Ik-Soo
    • International Journal of Industrial Entomology and Biomaterials
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    • 제24권1호
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    • pp.41-47
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    • 2012
  • The Scarites aterrimus (Coleoptera: Carabidae) dwells exclusively on coastal sandy dunes. Previously, we investigated the nation-wide magnitude and nature of genetic diversity of the species using mitochondrial COI gene and found moderate to low magnitude of sequence diversity, the presence of closely related haplotypes, and relatively high gene flow estimate. Based on these observations we concluded that the species had no historical barriers that bolster genetic subdivision and possible population decline. In this study, we additionally sequenced mitochondrial COII gene from 23 individuals collected from 9 Korean localities to confirm previous findings. Sequencing of 688 bp COII gene provided 5 haplotypes ranging in sequence divergence from 0.145% to 0.291% (1 ~ 2 bp), further confirming low sequence divergence of the species. Gene flow estimates and genetic diversity estimates also support the previous findings that there had been no historical barriers that bolster genetic subdivision.

PIC simulation study of the turbulence of the Alfven ion-cyclotron waves induced by electromagnetic ion-cyclotron instability

  • Kaang, Helen H.;Ryu, Chang-Mo;Mok, Chinook;Rha, Ki-Cheol
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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    • pp.29.3-29.3
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    • 2011
  • The turbulence in the nonlinear regime of the electromagnetic ion-cyclotron (EMIC) instability are investigated via a particle-in-cell (PIC) simulation. EMIC instability arises from anisotropic ion temperature and excites the Alfven ion-cyclotron (AIC) waves. The excited AIC waves undergo inverse-cascade via the nonlinear wave interaction of two AIC and one ion density modes. Induced ion density modes are the normal and second harmonic ion-acoustic (IA) waves. They have the same group velocity, but the second harmonic IA mode only generates the longitudinal electric field.

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Enhancement of Mechanical Properties in Microlaminate Composite materials Produces by Physical Vapor Deposition

  • Kwon, Sik-Chol;Rha, Jong-Joo;Beck, Woon-Seung
    • 한국진공학회지
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    • 제6권S1호
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    • pp.80-88
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    • 1997
  • The attempt to enhance the strength of materials has been an important subject for materials engineering and scientists. The strength of materials is termed as the ability to support high load without excessive deformation and without breaking catastrophically. The control of dislocation densities and barriers to the movement of dislocations have been considered to be the important methods for the strengthening materials. One of the approaches is mechanical blocking of dislocations by alternately depositing material layers. The typical structure of materials is multilayered and laminated composites. The thickness of each layer is typically in the range of nanometer. Ton avoid confusion with other terminology they may be defined as microlaminate composite materials. The manufacturing process of multilayered laminate structure will be introduced. And the current theoretical theories will be reviewed in view of strengthening of microlaminte composite materials.

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VoIP 보안관련 주요기술에 대한 분석 (Analysis of key technologies related to VoIP security)

  • 나성훈;신현식
    • 한국전자통신학회논문지
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    • 제5권4호
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    • pp.385-390
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    • 2010
  • VoIP(Voice over IP)서비스는 기존의 일반전화와 달리 인터넷망을 이용하여 음성 및 영상통화를 제공하는 서비스이다. VoIP의 사용이 보편화되고 발전되면서 보안의 위협도 계속 발전하고 있다. 이에대해 다양한 측면에서 VoIP의 보안에 대한 문제점 및 취약성에 대해 알아보고, 이 취약성을 해결하기 위한 방법인 보안 솔루션의 주요기술에 대해 알아보고자 한다.

공공부문의 서비스품질 측정모형 개발 (Developing the Measurement Model of Service Quality in the Public Sector)

  • 라준영;이승규
    • 산업공학
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    • 제20권3호
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    • pp.339-352
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    • 2007
  • Beyond SERVQUAL-based service quality research, we develop a measurement model of public service quality that would provide researchers and practitioners in the public sector with a foundation for systematic investigation and implementation. Firstly, we explore the attributes of public service quality that lead to customer satisfaction by using the critical incident technique (CIT). We identified four dimensions of public service qualities. We also found that the critical attributes of service quality differ according to the types of customers. Secondly, to achieve a high degree of empirical confidence, we conduct statistical tests and analyses on the classification scheme and on the attributes of service quality that we derived from the CIT analysis. Through these analyses, we could remove the redundancy among attributes and group the attributes into new constructs, which are mutually exclusive and exhaustive; we built a more sophisticated measurement model of service quality.

자녀의 발달단계에 맞는 새로운 부모역할 제안: 변화하는 부모역할 개념과 수행을 중심으로 (A suggestion for new parental roles according to children's developmental stages: The changing parental roles and practices)

  • 나종혜
    • 한국생활과학회지
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    • 제14권3호
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    • pp.411-421
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    • 2005
  • This current study was designed to explore the meaning of being a mother and a father in contemporary Korean society by examining their roles perceived by mothers and fathers with children at different developmental stages. A total of three hundred and ninety four couples with children aged from one to seventeen years were recruited for the study, and they were asked to complete a set of questionnaires about paternal and maternal roles each. A modified version of Generative Fathering Scales by Lee et al.(1999), was used to measure the roles perceived by fathers and mothers in two areas: (1) parenting responsibilities and (2) involvement in childrearing practices. The parental roles, as expected, were viewed differently by the surveyees with children at different ages: the younger child/ren a father has, the more involvement he emphasizes in childrearing. These results indicate that the roles of mothers and fathers should be considered in the context of developing children.

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Statistical Method for Implementing the Experimenter Effect in the Analysis of Gene Expression Data

  • Kim, In-Young;Rha, Sun-Young;Kim, Byung-Soo
    • Communications for Statistical Applications and Methods
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    • 제13권3호
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    • pp.701-718
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    • 2006
  • In cancer microarray experiments, the experimenter or patient which is nested in each experimenter often shows quite heterogeneous error variability, which should be estimated for identifying a source of variation. Our study describes a Bayesian method which utilizes clinical information for identifying a set of DE genes for the class of subtypes as well as assesses and examines the experimenter effect and patient effect which is nested in each experimenter as a source of variation. We propose a Bayesian multilevel mixed effect model based on analysis of covariance (ANACOVA). The Bayesian multilevel mixed effect model is a combination of the multilevel mixed effect model and the Bayesian hierarchical model, which provides a flexible way of defining a suitable correlation structure among genes.