• Title/Summary/Keyword: 3차해석

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The Effect of Group Mean Differences upon Factor Analysis (상관행렬의 구조분석에서 집단평균차이의 효과: 요인분석기법을 중심으로)

  • 김청택;이소영
    • Survey Research
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    • v.2 no.2
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    • pp.109-130
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    • 2001
  • The purpose of this study is (1) to demonstrate that ignoring group differences may mislead to incorrect conclusion when analyzing correlation data (e.g.. factor analysis). (2) to highlight the importance of the data analytic method considering group differences. and (3) to provide ways of incorporating group differences in data analysis. In study 1. ignoring group difference in factor analysis may mislead to incorrect factor structure. To remedy this. z-transform method and group analysis tool in covariance structure models were suggested. In study 2. the group differences effect was illustrated by using real data (IQ test data).

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Temperature and Flow Velocity Simulation for Fire in Synthetic Heat Transfer Fluid Boiler (열매유 보일러 내부 화재에 따른 온도 및 속도분포 시뮬레이션)

  • Kim, Yeob-Rae;Lee, Dong-Myung;Kim, Yun-Zeung
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2012.04a
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    • pp.472-475
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    • 2012
  • MDF(Medium Density Fiberboard) 제조공정에 필요한 열매유(SHTF, Synthetic Heat Transfer Fluid)를 가열하는 보일러에서 화재가 발생하였다. 열매유 보일러는 1차 패스, 2차 패스, 3차 패스로 구성되어 있으며, 화재가 발생된 1차 패스 연소대 위쪽 14단 부근에서 열매유가 방출되었다. 화재확산으로 인한 조사내용 및 데이터를 토대로 화재 시뮬레이션용 전산유체역학인 ANSYS-CFX를 이용하여 재현하고 화재 모델링 해석 및 분석을 통해 화재 온도를 산정하고 피해의 범위를 규정하였다. 본 화재 사고로 설비의 운전 및 소재에 대한 피해를 규정하고, 이론에 의한 과학적인 정밀 조사를 실시하여 향후의 안전 운전을 위한 제안을 하고자 한다.

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A Study on the Construal Level and Intention of Autonomous Driving Taxi According to Message Framing (해석수준과 메시지 프레이밍에 따른 자율주행택시의 사용의도에 관한 연구)

  • Yoon, Seong Jeong;Kim, Min Yong
    • Journal of Intelligence and Information Systems
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    • v.24 no.3
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    • pp.135-155
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    • 2018
  • The purpose of this study is to analyze the difference of interpretation level and intention to use message framing when autonomous vehicle, which is emerging as the product of 4th industrial revolution, is used as taxi, Interpretation level refers to the interpretation of a product or service, assuming that it will happen in the near future or in the distant future. Message framing refers to the formation of positive or negative expressions or messages at the extremes of benefits and losses. In other words, previous studies interpret the value of a product or service differently according to these two concepts. The purpose of this study is to investigate whether there are differences in intention to use when two concepts are applied when an autonomous vehicle is launched as a taxi. The results are summarized as follows: First, the message format explaining the gain and why should be used when using the autonomous taxi in the message framing configuration, and the loss and how when the autonomous taxi is not used. Messages were constructed and compared. The two message framing differed (t = 3.063), and the message type describing the benefits and reasons showed a higher intention to use. In addition, the results according to interpretation level are summarized as follows. There was a difference in intentions to use when assuming that it would occur in the near future and in the near future with respect to the gain and loss, Respectively. In summary, in order to increase the intention of using autonomous taxis, it is concluded that messages should be given to people assuming positive messages (Gain) and what can happen in the distant future. In addition, this study will be able to utilize the research method in studying intention to use new technology. However, this study has the following limitations. First, it assumes message framing and time without user experience of autonomous taxi. This will be different from the actual experience of using an autonomous taxi in the future. Second, self-driving cars should technical progress is continuing, but laws and institutions must be established in order to commercialize it and build the infrastructure to operate the autonomous car. Considering this fact, the results of this study can not reflect a more realistic aspect. However, there is a practical limit to search for users with sufficient experience in new technologies such as autonomous vehicles. In fact, although the autonomous car to take advantage of the public transportation by taxi is now ready for the road infrastructure, and technical and legal public may not be willing to choose to not have enough knowledge to use the Autonomous cab. Therefore, the main purpose of this study is that by assuming that autonomous cars will be commercialized by taxi you can do to take advantage of the autonomous car, it is necessary to frame the message, why can most effectively be used to find how to deliver. In addition, the research methodology should be improved and future research should be done as follows. First, most students responded in this study. It is also true that it is difficult to generalize the hypotheses to be tested in this study. Therefore, in future studies, it would be reasonable to investigate the population of various distribution considering the age, area, occupation, education level, etc. Where autonomous taxi can be used rather than those who can drive. Second, it is desirable to construct various message framing of the questionnaire, but it is necessary to learn various message framing in advance and to prevent errors in response to the next message framing. Therefore, it is desirable to measure the message framing with a certain amount of time when the questionnaire is designed.

An Analytical Study on the Structural Behavior of the Composite Slab with New-Shaped Deckplate (신형상의 합성용 데크플레이트를 사용한 합성슬래브의 구조적 거동에 관한 해석적 연구)

  • Moon, Tae Sup;Bae, Jong Woo
    • Journal of Korean Society of Steel Construction
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    • v.11 no.2 s.39
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    • pp.181-190
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    • 1999
  • The objective of this study is to investigate the structural behavior of the composite slabs with the new-shaped deckplate. In order to examine the deckplate as structural members, the composite slabs with new-shaped deckplate are compared and verified with the international design codes, and the simple inertia-moment equation of the composite slabs is suggested from the regression analysis of the results of the experiments. Besides, the finite element analysis was added on the purpose of the observation of structural behavior of the section items such as the Locking rib and the Dovetail. 36 experiments of composite slabs were performed with two new-type deckplates. And the finite-element analysis was performed by ABAQUS package with the function of the 3-dimension solid modeling.

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해석적 방법을 이용한 Worst Hot 조건에서 질량변화의 여부에 따른 발사시 열해석

  • Kim, Hui-Kyung;Choi, Joon-Min;Hyun, Bum-Seok
    • Aerospace Engineering and Technology
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    • v.3 no.2
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    • pp.42-49
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    • 2004
  • Analytical solutions are developed to predict temperature of a satellite box during launch stage under the assumption of worst hot condition. The considered time period is from fairing jettison to separation of satellite during launch stage. After fairing jettison, a box mounted on outer surface of satellite are exposed to space environments such as direct solar flux, Earth IR, Albedo, and free molecular heating. The thermal governing equation is simplified to 1st order ordinary differential equation such that analytic solutions are acquired after the box is assumed as a single lumped mass. The analytical solutions are also available for mass varying box. Finally, the practical application is performed for the case of STSAT-1 launch scenario.

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An Efficient Approach on Reliability Analysis under Multidisciplinary Analysis Systems (다분야 통합해석 시스템의 효율적인 신뢰성 해석기법 연구)

  • Ahn, Joong-Ki;Kwon, Jang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.33 no.3
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    • pp.18-25
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    • 2005
  • Existing methods have performed the reliability analysis using nonlinear optimization techniques. This is mainly due to the fact that they directly apply Multidisciplinary Design Optimization(MDO) frameworks to the reliability analysis formulation. Accordingly, the reliability analysis and the Multidisciplinary Analysis(MDA) are tightly coupled in a single optimizer, which hampers utilizing the recursive and function-approximation based reliability analysis methods such as the Advanced First Order Reliability Method(AFORM). In order to utilize the efficient reliability analysis method under multidisciplinary analysis systems, we propose a new strategy named Sequential Approach on Reliability Analysis under Multidisciplinary analysis systems(SARAM). In this approach, the reliability analysis and the MDA are decomposed and arranged in a sequential manner, making a recursive loop. The efficiency of the SARAM method was verified using three illustrative examples taken from the literatures. Compared with existing methods, it showed the least number of subsystem analyses over other methods while maintaining accuracy.

Flow Characteristics through the Singok Submerged Weir in Downstream of the Han River (한강하류 신곡수중보의 흐름특성)

  • Kim, Su Jin
    • Proceedings of the Korea Water Resources Association Conference
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    • 2020.06a
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    • pp.20-20
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    • 2020
  • 신곡수중보는 한강종합개발사업(1982년~1986년) 중 하도정비로 인하여 상시 수위가 저하됨으로써 조수의 과도한 역류 등으로 발생하는 이수상의 문제점을 해결하고 상류에 설치된 잠실수중 보 사이의 수위유지 및 하천 공간 이용의 극대화, 연안 농경지의 용수공급 및 하천환경 보전을 목적으로 건설되어, 「잠실 및 신곡수중보 관리규정(1986)」 및 「신곡수중보 운영 매뉴얼」에 의해 관리·운영되고 있다. 신곡수중보는 준공된 이래로 한강하류의 흐름 해석에 있어 중요한 기준과 경계로서 이와 관련한 다양한 연구가 진행되었다. 신곡수중보로 인한 흐름의 변화가 하상과 생태에 미치는 영향에 관한 연구와 하구역에서의 조위 및 흐름특성과 밀도류의 거동에 관한 1, 2차원 수치해석연구가 활발히 진행되었다. 본 연구에서는 그동안 1, 2차원 수치해석연구로 한정되었던 신곡수중보 흐름특성에 관련하여 실제 수문 운영 방식을 반영한 3차원 수치해석을 수행하여 구조물의 상·하류에서 발생하는 와류 및 이차류와 같은 3차원적 흐름 구조와 이에 따른 지형의 침식·퇴적 및 구조물에 미치는 영향 등을 구체적으로 분석하였다. 우선, 신곡수중보 운영 매뉴얼과 실제 가동보 운영시스템을 비교하여 수문개방 시기, 유량 기준의 수문 운영 방법, 수위 변화에 따른 수문 운영 방법, 수문개방 순서를 분석하고 신곡수중보 주변 흐름에 대한 3차원 수치해석모형 구축을 위한 경계조건을 산정하였다. 수치해석에는 상용프로그램인 FLOW-3D를 사용하였으며, 경계처리기법 및 난류해석을 위해 FAVOR 기법과 RNG k-ε 모델을 적용하였다. 수문 동시개방 개수, 수문 개방 위치 및 순서, 개방 높이에 대한 조건을 변화시켜 구성한 시나리오에 대해 수치해석 후, 유속, 난류에너지, 이차류 등의 흐름특성을 분석하고 상·하류 수위차에 따른 방류량을 산정하여 시설물의 관리안을 도출하고 운영 매뉴얼의 개정안을 제시하였다.

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Case Study on Influential Factors of Nonlinear Response History Analysis - Focused on 1989 Loma Prieta Earthquake - (비선형 응답이력해석의 영향인자에 대한 사례연구 - 1989 Loma Prieta 지진 계측기록을 중심으로 -)

  • Liu, Qihang;Lee, Jin-Sun
    • Journal of the Korean Geotechnical Society
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    • v.33 no.12
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    • pp.45-58
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    • 2017
  • As many seismic codes for various facilities are changed into a performance based design code, demand for a reliable nonlinear response-history analysis (RHA) arises. However, the equivalent linear analysis has been used as a standard approach since 1970 in the field of site response analysis. So, the reliability of nonlinear RHA should be provided to be adopted in replace of equivalent linear analysis. In this paper, the reliability of nonlinear RHA is reviewed for a layered soil layer using Loma Prieta earthquake records in 1989. For this purpose, the appropriate way for selecting nonlinear soil models and the effect of base boundary condition for 3D analysis are evaluated. As a result, there is no significant differences between equivalent linear and nonlinear RHA. In case of 3D analysis, absorbing boundary condition should be applied at base to prevent rocking motion of the whole model.

An application of Smoothed Particle Hydrodynamics on intake system analysis in a dam (입자법을 이용한 댐 취수 운영의 3차원 해석 적용)

  • Kim, Sunghoon;Cho, Kwangjoon;Park, Chungik;Moon, Sukju;Kim, Jongchan
    • Proceedings of the Korea Water Resources Association Conference
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    • 2019.05a
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    • pp.92-92
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    • 2019
  • 최근 기존의 격자방식의 해석 방법을 벗어나 해석 영역에 대한 분할을 별도로 고려치 않는 수치기법의 실무적 적용사례가 증가 하고 있으며, 이러한 방식중 SPH(Smoothed Particle Hydrodynamics) 방식이 근자에 수자원 분야에서도 도입되어 관수로 및 개수로 해석 또는 복합해석 등에 활용된 바 있다. 최초 도입된 무격자방식의 모형들은 주로 복잡한 형상을 지니는 유체기계 등에 활용성이 높았던 바, 큰 규모의 해석 도메인을 가지는 수자원 분야에서의 SPH의 실무적용 평가와 효율성의 확보를 위해서, 본 연구는 국내 댐을 시범 대상으로 하여 SPH 수치해석 툴을 적용하고자 하였다. 분석 대상댐은 국내 P댐으로서 관리수위의 변동은 크지 않으나, 댐 직상류의 만곡이 심하고 다수의 대규모 취수구를 가진 곳으로 상시 발전방류 및 수시 댐 수문방류에 의해 유체의 흐름이 2,3차원의 복잡성을 띄고있기 때문에, 3차원 전산유체역학 Tool의 적용이 적절한 것으로 판단하였다. 해석을 위해 하류경계조건을 댐축과 문비로 설정하였고 상류 1km까지를 해석의 도메인으로 설정하였다. 소요시간을 줄이기 위해 여러 번의 모의를 거쳐 입자의 평균 입경은 0.6m로 제안하고 시격은 1초 미만(평균 0.5초)로 설정하였다. 수문 및 발전방류는 해당댐의 1~2년 빈도 수준에 해당하는 $5,000m^3/s$ 이하의 유량을 기준으로 하여 모의를 수행하였다. 모의의 안정성을 확보한 이후에는 해당 댐지역의 하류영향을 고려한 문비제어를 반영한 다양한 방식의 수문운영 및 취수지점의 순간 수위 영향을 검토하였다. 그 결과로 본 모의에서는 특정한 수문의 운영 조건에서는 댐수위 계측지점과 인근 취수지점 간에도 0.2m 수준의 순간 수위차가 발생할 수 있음을 보였으며, 이는 경우에 따라 취수시설의 일시적 장애요소로 발생할 수 있음을 의미한다. 따라서, 현재의 취수구조물과 문비운영 특성에 따라 발생가능한 취수장애를 줄일 수 있는 운영조건의 탐색을 위해서 수치모의를 추가로 하였으며, 이 때 댐축 상류의 유속분포에 대한 추가 검토도 수행하였다. 다만, 댐에서 방류시 하류조건에 대한 검토는 추후 보강되어야 할 것으로 판단된다.

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A Study on Development of the Secondary Reverse Vortex in Building Canyon (건물협곡에서의 2차 역회전 소용돌이 형성에 관한 연구)

  • Son, Minu;Kim, Do-Yong
    • Journal of the Korean Society for Environmental Technology
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    • v.19 no.6
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    • pp.528-535
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    • 2018
  • In this study, the effect of obstacle aspect ratio on vortex in building canyon was numerically investigated using a computational fluid dynamics(CFD) model. The sensitivity experiments were performed in the cases of increasing building length(L) and height(H) by the width(W) of building canyon. The wind vector fields and secondary reverse vortex in building canyon were discussed in this study. For the horizontal vortex, the vortex zone increased as the building length increases, but the vectors at the middle of building canyon began to change in the case of L/W=2.5. In the case of L/W=3.0, the smaller primary vortex was presented with the secondary reverse vortex. For the vertical vortex, the vortex zone increased as the building height increases, but the direction of vectors at the bottom of building canyon began to change in the case of H/W=2.5. In the case of H/W=3.5, the smaller primary vortex was presented with the secondary reverse vortex.