• 제목/요약/키워드: Orders Analysis

검색결과 786건 처리시간 0.032초

후향계단 유동장 저차 모델링을 위한 ARX 설계 기법 (ARX Design Technique for Low Order Modeling of Backward-Facing-Step Flow Field)

  • 이진익;이은석
    • 한국항공우주학회지
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    • 제40권10호
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    • pp.840-845
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    • 2012
  • 본 논문에서는 후향계단(Backward Facing Step) 유동장의 유동운동에 대한 ARX(Auto Regressive eXogenous) 모델링 기법을 제시한다. BFS 유동장 모델링을 위해 밀도를 모드분석을 통해 고유 공간모드와 시간계수를 추출한다. 입력 차수와 상태변수 차수는 각각 유동장 스팩트럼 분석과 시간계수 분석을 통해 결정한다. 또한, 유동장의 속도 분석을 통해 ARX의 입력 지연 차수를 결정한다. 한편, ARX 모델의 계수는 신경망을 이용하여 설계한다.

지하차도 건설에 따른 기존 지하철터널 안정성에 대한 연구 (A Study on the Stability of Existing Subway Tunnel due to Construction of New Underpass)

  • 정지승;최재영;이진혁
    • 한국안전학회지
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    • 제31권2호
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    • pp.57-63
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    • 2016
  • Recently, subways in the city are formed a vast underground network which is interfered with construction when large-scale infrastructure will be planned to nearby existing subway tunnels. Researches have been restricted to estimate stability of existing subway tunnel due to adjacent excavation causued by small construction such as buildings. In this paper, OO underpass is planned on the top of existing subway tunnel, which will be need large-scale excavation, is selected as a subject of study. And the purpose of this study is to analyze the effects on existing subway tunnel due to excavation by stages on construction of underpass. The 3D-numerical analysis was performed by using the MIDAS/GTS program. The stability on existing subway tunnel caused by sequential excavation is analysed using numerical results. Based on the analysis, the excavation orders and reinforcement methods was suggested for stability of exiting subway tunnel.

Data-based Stability Analysis for MIMO Linear Time-invariant Discrete-time Systems

  • Park, Un-Sik;Ikeda, Masao
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2005년도 ICCAS
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    • pp.680-684
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    • 2005
  • This paper presents a data-based stability analysis of a MIMO linear time-invariant discrete-time system, as an extension of the previous results for a SISO system. In the MIMO case, a similar discussion as in the case of a SISO system is also applied, except that an augmented input and output space is considered whose dimension is determined in relation to both the orders of the input and output vectors and the numbers of inputs and outputs. As certain subspaces of the input and output space, both output data space and closed-loop data space are defined, which contain all the behaviors of a system, respectively, with zero input in open-loop and with a control input in closed-loop. Then, we can derive the data-based stability conditions, in which the open-loop stability can be checked by using a data matrix whose column vectors span the output data space and the closed-loop stability can also be checked by using a data matrix whose column vectors span the closed-loop data space.

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하상 변화에 따른 저서성 대형무척추동물의 서식기능군 분석 (Analysis of Functional Habitat Groups of Benthic Macroinvertebrates according to Changes in the Riverbed)

  • 이슬희;이미진;서을원;이종은
    • 한국환경과학회지
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    • 제26권3호
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    • pp.373-380
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    • 2017
  • This study identified the effect of changes in the riverbed on the benthic macroinvertebrate communities. The benthic macroinvertebrates collected from the surveyed sites belonged to 119 species, 65 families, 20 orders, and 7 classes in 4 phyla. The number of Ephemeroptera, Plecoptera, and Trichoptera (E.P.T) species was 42, 10, and 8, respectively, in the tributary, confluence, and Nakdong River sites. Lotic species (Hydropsychidae) showed a high density at the tributary sites, whereas lentic species (Chironomidae) showed a high density at the confluence and Nakdong River sites. Community analysis showed that the Dominance Index (DI) was 0.54 in tributary sites, and dominance indices increased closer to the Nakdong River sites. The diversity index (H') was inversely proportional to DI. The ratio of Burrowers species (BU) at the surveyed sites increased closer to the Nakdong River sites. Analysis of common species showed 37 species (34.6%) between the tributary and confluence sites and 66 species (51.5%) between the confluence and Nakdong River sites.

Membrane Inlet-based Portable Time-of-flight Mass Spectrometer for Analysis of Air Samples

  • Kim, Tae-Kyu;Jung, Kyung-Hoon;Yoo, Seung-Kyo;Jung, Kwang-Woo
    • Bulletin of the Korean Chemical Society
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    • 제26권2호
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    • pp.303-308
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    • 2005
  • A miniaturized time-of-flight mass spectrometer with an electron impact ionization source and sheet membrane introduction has been developed. The advantages and features of this mass spectrometer include high sensitivity, simple structure, low cost, compact volume with field portability, and ease of operation. A mass resolution of 400 at m/z 78 has been obtained with a 25 cm flight path length. Under optimized conditions, the detection limits for the volatile organic compounds (VOCs) studied were 0.2-10 ppm by volume with linear dynamic ranges greater than three orders of magnitude. The response times for various VOCs using a silicone membrane of 127 $\mu$m thickness were in the range 4.5-20 s, which provides a sample analysis time of less than 1 minute. These results indicate that the membrane introduction/time-of-flight mass spectrometer will be useful for a wide range of field applications, particularly for environmental monitoring.

접합요소를 도입한 기초지반의 유한요소해석 (The Finite Element Analysis of Foundation Layer by Introducing Interface Element)

  • 양극영;이대재
    • 한국전산구조공학회논문집
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    • 제15권1호
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    • pp.9-20
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    • 2002
  • 본 연구의 목적은 비선형 흙-구조물 상호 작용문제를 연구하기 위한 계산 절차를 개발하는 것이다. 흙-구조물 상호 작용 거동을 연구하기 위하여 연직과 수평하중을 동시에 받은 대상기초와 강널말뚝으로 보강된 기초지반에 대한 유한 요소 수치해석을 하였으며 흙과 기초구조물 사이의 상호작용 거동을 모델하기 위하여 접합요소를 사용하였다 주 해석 결과는 다음과 같다. 1. 침하와 측방변위의 예측에 대해서는, 접합요소를 사용한 결과가 더 큰 값을 얻었다. 2. 극한지지력 결정에 대해서는 접합요소를 사용한 경우가 약 12%정도 더 작게 나타났다 3. 대상기초의 수평과 연직변위는 접합요소의 영향을 받았다.

STUDY OF CORE SUPPORT BARREL VIBRATION MONITORING USING EX-CORE NEUTRON NOISE ANALYSIS AND FUZZY LOGIC ALGORITHM

  • CHRISTIAN, ROBBY;SONG, SEON HO;KANG, HYUN GOOK
    • Nuclear Engineering and Technology
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    • 제47권2호
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    • pp.165-175
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    • 2015
  • The application of neutron noise analysis (NNA) to the ex-core neutron detector signal for monitoring the vibration characteristics of a reactor core support barrel (CSB) was investigated. Ex-core flux data were generated by using a nonanalog Monte Carlo neutron transport method in a simulated CSB model where the implicit capture and Russian roulette technique were utilized. First and third order beam and shell modes of CSB vibration were modeled based on parallel processing simulation. A NNA module was developed to analyze the ex-core flux data based on its time variation, normalized power spectral density, normalized cross-power spectral density, coherence, and phase differences. The data were then analyzed with a fuzzy logic module to determine the vibration characteristics. The ex-core neutron signal fluctuation was directly proportional to the CSB's vibration observed at 8Hz and15Hzin the beam mode vibration, and at 8Hz in the shell mode vibration. The coherence result between flux pairs was unity at the vibration peak frequencies. A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations.

빅 데이터 분석을 통한 해외건설 빅 이슈 개발에 관한 기초연구 (A preliminary Study on Development of Overseas Construction Big Issues Based on Analysis of Big Data)

  • 박환표;한재구
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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    • pp.93-94
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    • 2017
  • This study have derived the big issue of overseas construction through big data analysis. For identification of big issues on overseas construction, domestic online articles, 30 daily newspapers like the JoongAng Ilbo, 7 construction related articles including construction economy and 1,759 local newspapers and small media companies were analyzed from October 1st, 2015 to September 30th, 2016. 13,884 cases in total were used for big data analyses and big issue candidates were identified. The analysis result is as shown below. First, looking into major issues on overseas construction for a year, construction orders in the Middle East decreased because of the drop in oil prices. Accordingly, there were discussions on concerns and crises we may face as profitabilities worsened in overseas construction. Second, analyzing main concern based on 8 key words on overseas construction among construction issues for the last one year, it was found as following: Region (29.4%), Business environment (21.4%), Group (15.8%), Profitability (14.5%), Policy and Institution (7.8%), Market environment (4.2%), Business (project) (4.15%), and Education (3.2%). Third, among 30 issues on 8 key words, 10 key issues that are likely to spread and continue were identified. Then, a semantic network map among key words and centrality were analyzed.

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광반응 HPLC를 이용한 시호 사포닌의 분석 (Analysis of Saikosaponins by HPLC with Photoreduction Fluorescence Detection)

  • 신영근;조경희;권수진;도영미;황귀서;박정일;박만기
    • 약학회지
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    • 제40권1호
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    • pp.41-45
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    • 1996
  • A high performance liquid chromatography using photoreduction fluorescence detection was described for the analysis of saikosaponins. Saikosaponins were separated on an $NH_2$ column using acetonitrile and aqueous 2-tert-butylanthraquinone(t-BAQ) as mobile phase. Column effluent was passed through a 40cm PTFE capillary tube coiled around a 10W UV lamp to reduce t-BAQ to a highly fluorescent dihydroxyanthracene derivative which was detected by a fluorescence detector. The optimal concentration of t-BAQ was found to be $6{\times}10^{-5}M$ and the optimal reaction time to be 2 seconds. The detection limit for saikosaponin a and d by this method was found to be about 280ng and 80ng. The dynamic linear range was over two orders and the correlation coefficient of the calibration curve of them was 0.998.

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Quantitative Determination of Nicotine in a PDMS Microfluidic Channel Using Surface Enhanced Raman Spectroscopy

  • Jung, Jae-hyun;Choo, Jae-bum;Kim, Duck-Joong;Lee, Sang-Hun
    • Bulletin of the Korean Chemical Society
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    • 제27권2호
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    • pp.277-280
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    • 2006
  • Rapid and highly sensitive determination of nicotine in a PDMS microfluidic channel was investigated using surface enhanced Raman spectroscopy (SERS). A three-dimensional PDMS microfluidic channel was fabricated for this purpose. This channel shows a high mixing efficiency because the transverse and vertical dispersions of the fluid occur simultaneously through the upper and lower zig zag-type blocks. A higher efficiency of mixing could also be obtained by splitting each of the confluent streams into two sub-streams that then joined and recombined. The SERS signal was measured after nicotine molecules were effectively adsorbed onto silver nanoparticles by passing through the three-dimensional channel. A quantitative analysis of nicotine was performed based on the measured peak area at 1030 $cm^{-1}$. The detection limit was estimated to be below 0.1 ppm. In this work, the SERS detection, in combination with a PDMS microfluidic channel, has been applied to the quantitative analysis of nicotine in aqueous solution. Compared to the other conventional analytical methods, the detection sensitivity was enhanced up to several orders of magnitude.