• Title/Summary/Keyword: DAE 모델

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An Analytic Study on the Valve Rotation Behavior of an Internal Combustion Engine (내연기관 밸브회전 거동에 관한 해석적 연구)

  • Kim, Do-Joong;Youn, Jae-Won;Kim, Jin-Woung;Song, Jin-Ook
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.2
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    • pp.184-193
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    • 2006
  • Rotation of intake and exhaust valves are very closely related to the long term durability of automotive engines. If the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. A principle of valve rotation mechanism was presumed based on some findings from experiments, and computer programs were developed to simulate the valve rotation phenomena. In this study we investigated the valve rotation mechanism by using the computer simulation models.

XML Signature Model Design using Signature Value Hide (서명값 은닉을 이용한 XML 전자서명 모델 설계)

  • Ko, Hoon;Kim, Dae-Won;Shin, Yong-Tae
    • Annual Conference of KIPS
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    • 2003.11c
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    • pp.1873-1876
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    • 2003
  • 최근 전자상거래 확산에 따라 전자서명, 키관리 및 인증서비스가 새롭게 부상하고 있으며, 여기에 적용하기 위한 정보보호 기반기술로는 암호화 기술, 인증기술, 전자서명, PKI(Pulbic Key Infrastructure) 및 WPKI(Wireless PKI)등이 있다. 암호화 기술은 합법적 참여자들 간에 메시지 변/복조 규칙에 대한 약속을 정하고, 이 규칙에 따라 송신하려는 메시지를 암호화시켜 전달 혹은 보관하며, 메시지 수신시 또는 접근 권한이 있는 사람이 필요에 따라 이를 복호화 하도록 하는 기술을 말한다. 전자서명은 종래의 종이 문서에 표기하던 수기 서명이나 인장 효과를 전자적 매체내에 저장 또는 전송되는 전자 문서상에 효과적으로 부여하는 전자적 서명 방식이다. e-business 활성화를 위한 정부의 적극적인 참여와 지원을 바탕으로 받은 전자상거래 관련 사업들이 등장하고 있다. 이러한 전자상거래에 사용되는 기반 기술로서 XML(extensible Markup Language)기술이 사용되고 있다. 본 연구에서는 서명값을 XML 문서 안에 포함해서 전송 하는 방법으로 문서의 무결성과 비밀성을 보장하고자 한다.

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Numerical Verification of Hybrid Optimization Technique for Finite Element Model Updating (유한요소모델개선을 위한 하이브리드 최적화기법의 수치해석 검증)

  • Jung, Dae-Sung;Kim, Chul-Young
    • Journal of the Earthquake Engineering Society of Korea
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    • v.10 no.6 s.52
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    • pp.19-28
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    • 2006
  • Most conventional model updating methods must use mathematical objective function with experimental modal matrices and analytical system matrices or must use information about the gradient or higher derivatives of modal properties with respect to each updating parameter. Therefore, most conventional methods are not appropriate for complex structural system such as bridge structures due to stability problem in inverse analysis with ill-conditions. Sometimes, moreover, the updated model may have no physical meaning. In this paper, a new FE model updating method based on a hybrid optimization technique using genetic algorithm (GA) and Holder-Mead simplex method (NMS) is proposed. The performance of hybrid optimization technique on the nonlinear problem is demonstrated by the Goldstein-Price function with three local minima and one global minimum. The influence of the objective function is evaluated by the case study of a simulated 10-dof spring-mass model. Through simulated case studies, finally, the objective function is proposed to update mass as well as stiffness at the same time. And so, the proposed hybrid optimization technique is proved to be an efficient method for FE model updating.

Estimation of Mechanical Properties for Particle Dispersed Composites (입자 분산 복합재료의 기계적 성질 추정)

  • Tak Jin Moon;Dae Soon Im
    • Journal of the Korean Chemical Society
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    • v.26 no.6
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    • pp.414-420
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    • 1982
  • The mechanical properties of nickel particle polyethylene composites were estimated by using a finite element method. Two steps were carried out in this analysis; the first step was to consider an unit model composed of spherical cell in the center of the matrix and the second step was to consider a total model composed of unit model. Two phase and three phase models were used, since another third phase were observed between matrix and nickel particle. Finite element method permits the calculation of the stress and displacement, assuming the arbitrary loads. Elastic modulus, Poisson's ratio and stress distribution of composites were obtained from this output. Comparison of the calculation by finite element method and the experimental results for Ni-filled polyethylene showed good agreement in tensile properties.

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Geoacoustic Model of Coastal Bottom Strata at Jeongdongjin in the Korean Continental Margin of the East Sea (동해 한국대륙주변부 정동진 연안 지층의 지음향 모델)

  • Ryang, Woo-Hun;Kim, Seong-Pil;Kim, Dae-Choul;Hahn, Jooyoung
    • Journal of the Korean earth science society
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    • v.37 no.4
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    • pp.200-210
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    • 2016
  • Geoacoustic modeling is used to predict sound transmission through submarine bottom layers of sedimentary strata and acoustic basement. This study reconstructed four geoacoustic models for sediments of 50 m thick at the Jeongdongjin area in the western continental margin of the East Sea. Bottom models were based on the data of the highresolution air-gun seismic and subbottom profiles (SBP) with sediment cores. P-wave speed was measured by the pulse transmission technique, and the resonance frequency of piezoelectric transducers was maintained at 1MHz. Measurements of 42 P-wave speeds and 41 attenuations were fulfilled in three core sediments. For actual modeling, the P-wave speeds of the models were compensated to in situ depth below the sea floor using the Hamilton method. These geoacoustic models of coastal bottom strata will be used for geoacoustic and underwater acoustic experiments reflecting vertical and lateral variability of geoacoustic properties in the Jeongdongjin area of the East Sea.

Transient Analysis of High-rise Wall-Frame Structures with Outriggers under Seismic Load (초고층 전단벽-골조 아웃리거 구조시스템의 지진하중에 대한 시간이력해석)

  • Kim, Jin Man;Choe, Eun Hui;Park, Dae Gyu;Lee, Jae Hong
    • Journal of Korean Society of Steel Construction
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    • v.20 no.2
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    • pp.303-312
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    • 2008
  • In this paper, the seismic behavior of shear wal-frame systems is analyzed. The governing equations of the wall-frame systems with outrigger truss are formulated through the continuum approach and the whole structure is idealized as a shear-flexural cantileverwith rotational spring. The effect of shear deformation and flexural deformation of the wall-frame and outrigger trusses are considered and incorporated in the formulation of the wall-frame structures with and without outriggers are compared by using finite element analysis incorporated with the Newmark-${\beta}$ method. Numerical results are obtained and compared with the finite element package MIDAS. The proposed method is found to be simple and efficient, and provides reason ably accurate results in the early design stage of tall building structures.

A Generation from Entity-Relationship Model to XML Schema Model (개체-관계 모델에선 XML Schema의 생성)

  • Kim, Chang-Suk;Kim, Dae-Su;Son, Dong-Cheul
    • Journal of the Korean Institute of Intelligent Systems
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    • v.14 no.6
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    • pp.667-673
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    • 2004
  • The XML is emerging as standard language for data exchange on the Web. Therefore the demand of XML Schema(W3C XML Schema Spec.) that verifies XML document becomes increasing. However, XML Schema has a weak point for design because of its complication despite of various data and abundant expressiveness. This paper shows a simple way of design for XML Schema using a fundamental means for database design, the Entity-Relationship model. The conversion from the Entity-Relationship model to XML Schema can not be directly on account of discordance between the two models. So we present some algorithms to generate XML Schema from the Entity-Relationship model. The algorithms produce XML Schema codes using a hierarchical view representation. An important objective of this automatic generation is to preserve XML Schema's characteristics such as reusability, global and local ability, ability of expansion and various type changes.

A Study on Efficient Polynomial-Based Discrete Behavioral Modeling Scheme for Nonlinear RF Power Amplifier (비선형 RF 전력 증폭기의 효율적 다항식 기반 이산 행동 모델링 기법에 관한 연구)

  • Kim, Dae-Geun;Ku, Hyun-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.11
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    • pp.1220-1228
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    • 2010
  • In this paper, we suggest a scheme to develop an efficient discrete nonlinear model based on polynomial structure for a RF power amplifier(PA). We describe a procedure to extract a discrete nonlinear model such as Taylor series or memory polynomial by sampling the input and output signal of RF PA. The performance of the model is analyzed varying the model parameters such as sample rate, nonlinear order, and memory depth. The results show that the relative error of the model is converged if the parameters are larger than specific values. We suggest an efficient modeling scheme considering complexity of the discrete model depending on the values of the model parameters. Modeling efficiency index(MEI) is defined, and it is used to extract optimum values for the model parameters. The suggested scheme is applied to discrete modeling of various RF PAs with various input signals such as WCDMA, WiBro, etc. The suggested scheme can be applied to the efficient design of digital predistorter for the wideband transmitter.

GRAM Model Analysis of Groundwater Rebound in Abandoned Coal Mines (GRAM 모델을 이용한 폐탄광 지역 지하수 리바운드 현상 분석)

  • Choi, Yosoon;Baek, Hwanjo;Cheong, Young-Wook;Shin, Seung-Han;Kim, Gyoung-Man;Kim, Dae-Hoon
    • Tunnel and Underground Space
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    • v.22 no.6
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    • pp.373-382
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    • 2012
  • Cessation of dewatering usually results in groundwater rebound after closing an underground coal mine because the mine voids and surrounding strata flood up to the levels of decant points such as shafts and drifts. Several numerical models have been developed to predict the timing, magnitude and location of discharges resulting from groundwater rebound. This study reviews the numerical models such as VSS-NET, GRAM and MODFLOW, and compares their scopes of assessment at different spatial and time scales. In particular, the GRAM model was reviewed in details to implement it. This paper describes the implementation of GRAM model and its application to the Dongwon coal mine in Korea. The application showed that the groundwater level modeled at the shaft of Dongwon coal mine using the GRAM model is similar to the observed one in the field.

과학기술위성3호 시험인증모델 제작 및 시험

  • Park, Jong-O;Lee, Seong-Se;Lee, Seung-Heon;Son, Jun-Won;Lee, Seung-U;Sin, Gu-Hwan;Seo, Jeong-Gi;Park, Hong-Yeong;Lee, Dae-Hui;Lee, Jun-Ho
    • Bulletin of the Korean Space Science Society
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    • 2009.10a
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    • pp.28.3-28.3
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    • 2009
  • 과학기술위성 3호는 2007년 6월에 사업착수를 시작하여, 동년 8월 시스템요구사항검토회의(SRR)를 통해 임무 요구사항을 도출하였고, 동년 12월에 시스템기본설계검토회의(SDR)과 2008년 9월 시스템예비설계검토회의(PDR)를 개최하여 시험인증모델(EQM, Engineering& Qualification Model) 제작을 시작하여, 납품을 완료하고 ETB(Engineering Test Bed)상에서 유닛의 기능 시험 및 접속시험, 그리고 환경시험을 수행을 완료하였다. 또한 열구조모델 (STM, Structure and Thermal Model)도 제작을 완료하고 발사환경시험과 열평형 환경시험을 완료하였다. 이와같이 시험인증모델 및 열구조모델에 대한 지상에서의 시험과 검증이 완료된 시험결과를 바탕으로 2009년 9월 상세설계를 완료하고 비행모델 제작에 착수할 예정이다. 이 논문에서는 과학기술위성 3호의 시험인증모델에 대한 시험의 목적, 종류 그리고 검증에 대한 결과 그리고 향후 계획에 대해 발표하고자 한다. 참고로 과학기술위성 3호는 주탑재체인 다목적적외선영상시스템(MIRIS)은 우리 은하계의 근적외선 관측, 우주 배경복사 관측 및 지구 지표면의 적외선 영상 획득을 임무로 하고 있고, 부탑재체인 초소형 영상 분광기(COMIS)는 한반도 지역의 다중 스펙트럼 영상을 획득함으로써 대기관측 및 환경감시의 임무를 가지고 있다.

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