• Title, Summary, Keyword: analytical model

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Static and Free Vibration Analysis of FGM Plates on Pasternak Elastic Foundation (Pasternak 탄성지반위에 놓인 점진기능재료 판의 정적 및 자유진동 해석)

  • Lee, Won-Hong;Han, Sung-Cheon;Park, Weon-Tae
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.6
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    • pp.529-538
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    • 2016
  • The simplified plate theory is presented for static and free vibration analysis of power-law(P) and sigmoid(S) Functionally Graded Materials(FGM) plates. This theory considers the parabolic distribution of the transverse shear stress, and satisfies the condition that requires the transverse shear stress to be zero on the upper and lower surfaces of the plate, without the shear correction factor. The simplified plate theory uses only four unknown variables and shares strong similarities with classical plate theory(CPT) in many aspects such as stress-resultant expressions, equation of motion and boundary conditions. The material properties of the plate are assumed to vary according to the power-law and sigmoid distributions of the volume fractions of the constituents. The Hamilton's principle is used to derive the equations of motion and Winkler-Pasternak elastic foundation model is employed. The results of static and dynamic responses for a simply supported FGM plate are calculated and a comparative analysis is carried out. The results of the comparative analysis with the solutions of references show relevant and accurate results for static and free vibration problems of FGM plates. Analytical solutions for the static and free vibration problems are presented so as to reveal the effects of the power law index, elastic foundation parameter, and side-to-thickness ratio.

Modeling of Gas Permeability Coefficient for Cementitious Materials with Relation to Water Permeability Coefficient (시멘트계 재료의 기체 투기계수 해석 및 투수계수와의 상관성 연구)

  • Yoon, In-Seok
    • Journal of The Korean Society of Civil Engineers
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    • v.36 no.2
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    • pp.207-217
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    • 2016
  • Permeability can not be expressed as a function of porosity alone, it depends on the porosity, pore size and distribution, and tortuosity of pore channels in concrete. There has been considerable interest in the relationship between microstructure and transport in cementitious materials, however, it is very rare to deal with the theoretical study on gas permeability coefficient in connection with carbonation of concrete and the effect of volumetric fraction of cement paste or aggregate on the permeability coefficient. The majority of these researches have not dealt with this issue combined with carbonation of concrete, although carbonation can significantly impact on the permeability coefficient of concrete. In this study, fundamental approach to compute gas permeability of (non)carbonated concrete is suggested. For several compositions of cement pastes, the gas permeability coefficient was calculated with the analytical formulation, followed by a microstructure-based model. For carbonated concrete, reduced porosity was calculated and this was used for calculating the gas permeability coefficeint. As the result of calculation of gas permeability for carbonated concrete, carbonation leaded to the significant reduction of gas permeability coefficient and this was obvious for concrete with high w/c ratio. Meanwhile, the relationship between gas permeability and water permeability has a linear function for cement paste based on Klinkenberg effect, however, which is not effective for concrete. For the evidence of the modeling, YOON's test was accomplished and these results were compared to each other.

Determination of Baicalin and Baicalein Contents in Scutellaria baicalensis by NIRS (근적외선분광분석기를 이용한 황금(Scutellaria baicalensis)의 baicalin 및 baicalein 함량 분석)

  • Kim, Hyo-Jae;Kim, Se-Young;Lee, Young-Sang;Kim, Yong-Ho
    • Korean Journal of Plant Resources
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    • v.27 no.4
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    • pp.286-292
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    • 2014
  • Near infrared reflectance spectroscopy (NIRS) is a rapid and accurate analytical method for determining the composition of agricultural products and feeds. This study was conducted to measure baicalin, baicalein, and wogonin contents in Scutellaria baicalensis by using NIRS system. Total 63 samples previously were analyzed by HPLC, which showed baicalin, baicalein, and wogonin contents ranging 4.56 to 13.59%, 0.28 to 5.54%, and 0.50 to 1.63% with an average of 9.66%, 2.09% and 0.52%, respectively. Each sample was scanned by NIRS and calculated for calibration and validation equation. A calibration equation calculated by modified partial least squares(MPLS) regression technique was developed in which the coefficient of determination for baicalin, baicalein, and wogonin content was 0.958, 0.944, and 0.709, respectively. Each calibration equation was applied to validation set that was performed with the remaining samples not included in the calibration set, which showed high positive correlation both in baicalin and baicalein content file. In case of wogonin, the prediction model was needed more accuracy because of low $R^2$ value in validation set. These results demonstrate that the developed NIRS equation can be practically used as a rapid screening method for quantification of baicalin and baicalein contents in Scutellaria baicalensis.

A Construction Case of BRM 'Danwigwaje' in Basic Local Governments : Focussing on Gangbuk District of Seoul Special City (기초지방자치단체 기능분류체계(BRM)의 단위과제 구축 사례 서울특별시 강북구 사례를 중심으로)

  • Moon, Chan-il
    • The Korean Journal of Archival Studies
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    • no.49
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    • pp.247-275
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    • 2016
  • The classification scheme of records indicates a table that intends to express organic relations between records by organizing records and enabling internal order. Although the principles of organic classification have remained in traditional records management environment, they have been changed to "function and business" in the modern times. Therefore, Korea introduced a business reference model (BRM) based on function and business from 2008 and subsequently implemented its operation. However, it has been pointed out that the roles of the classification scheme of records have not been played because the analysis of "Danwigwaje," which belongs to the lowest level of business reference models, is poor. According to this indication, the Gangbuk District of Seoul Special City established a functional classification scheme by executing a business process analysis of "Danwigwaje." First, the record manager carried out analyses on the principles of "Danwigwaje," small function, and "Danwigwaje." Then, the functional classification scheme of "Danwigwaje" was modified by looking into the opinion inquiry process of the treatment department and performing a test operation. Through the case of the Gangbuk District in Seoul Special City, analytical procedures and methods of "Danwigwaje," as well as implications according to the establishment of a functional classification scheme of basic local governments, were arranged in a written format.

Evaluation of Deformation Characteristics and Vulnerable Parts according to Loading on Compound Behavior Connector (복합거동연결체의 하중재하에 따른 변형 특성 및 취약부위 산정)

  • Kim, Ki-Sung;Kim, Dong-wook;Ahn, Jun-hyuk
    • Journal of the Society of Disaster Information
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    • v.15 no.4
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    • pp.524-530
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    • 2019
  • Purpose: In this paper, we construct a detailed three-dimensional interface element using a three-dimensional analysis program, and evaluate the composite behavior stability of the connector by applying physical properties such as the characteristics of general members and those of reinforced members Method: The analytical model uses solid elements, including non-linear material behavior, to complete the modeling of beam structures, circular flanges, bolting systems, etc. to the same dimensions as the design drawing, with each member assembled into one composite behavior linkage. In order to more effectively control the uniformity and mesh generation of other element type contact surfaces, the partitioning was performed. Modeled with 50 carbon steel materials. Results: It shows the displacement, deformation, and stress state of each load stage by the contact adjoining part, load loading part, fixed end part, and vulnerable anticipated part by member, and after displacement, deformation, The effect of the stress distribution was verified and the validity of the design was verified. Conclusion: Therefore, if the design support of the micro pile is determined based on this result, it is possible to identify the Vulnerable Parts of the composite behavior connector and the degree of reinforcement.

Design of method to analyze UI structure of contents based on the Morphology (형태적 관점의 콘텐츠 UI구조 분석 방법 설계)

  • Yun, Bong Shik
    • Smart Media Journal
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    • v.8 no.4
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    • pp.58-63
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    • 2019
  • The growth of the mobile device market has changed the education market and led to the quantitative growth of various media education. In particular, smart devices, which have better interaction than existing PCs or consoles, can develop more user-friendly content, allowing various types of educational content and inducing changes in traditional education methods for consumers. Although many researchers recently suggest viable development methods or marketing elements of contents, development companies, and developers, until now, merely rely on the human senses. Therefore, it is necessary to study the actual user's smart-device based usability and experience environment. This study aims to propose an intuitive statistical processing method for analyzing the usability of game-type educational contents in terms of form, for popular games that have been released as a basis for analyzing the user experience environment. In particular, because the game industry has a sufficient number of similar examples, it is possible to conduct research based on big data and to use them for immediate decision-making between multiple co-developers through the analysis method proposed by the research. It is expected to become an analytical model that can communicate with other industries because it is effective in securing data sources.

Development and Verification of OGSFLAC Simulator for Hydromechanical Coupled Analysis: Single-phase Fluid Flow Analysis (수리-역학적 복합거동 해석을 위한 OGSFLAC 시뮬레이터 개발 및 검증: 단상 유체 거동 해석)

  • Park, Chan-Hee;Kim, Taehyun;Park, Eui-Seob;Jung, Yong-Bok;Bang, Eun-Seok
    • Tunnel and Underground Space
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    • v.29 no.6
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    • pp.468-479
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    • 2019
  • It is essential to comprehend coupled hydro-mechanical behavior to utilize subsurface for the recent demand for underground space usage. In this study, we developed a new simulator for numerical simulation as a tool for researching to consider the various domestic field and subsurface conditions. To develop the new module, we combined OpenGeoSys, one of the scientific software package that handles fluid mechanics (H), thermodynamics (T), and rock and soil mechanics (M) in the subsurface with FLAC3D, one of the commercial software for geotechnical engineering problems reinforced. In this simulator development, we design OpenGeoSys as a master and FLAC3D as a slave via a file-based sequential coupling. We have chosen Terzaghi's consolidation problem related to single-phase fluid flow at a saturated condition as a benchmark model to verify the proposed module. The comparative results between the analytical solution and numerical analysis showed a good agreement.

Comparison of The Importance of Evaluation Items for Landscape Performance and Sustainability Using Analytic Network Process (ANP) (ANP기법을 이용한 조경성능 및 친환경 평가항목 중요도 비교)

  • Ryu, Myeung-Ji;Lee, Hyung-Sook
    • Journal of the Korean Institute of Landscape Architecture
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    • v.47 no.6
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    • pp.45-52
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    • 2019
  • As international criteria and standards are required in the fields of design and construction, landscape performance must also be considered not only for the value of the landscape but also for providing quality assurance and sustainability. Given the lack of research on landscape performance, the present research was purposed to analyze the importance of potential assessment categories and items using an analytical network process. A list of assessment items, which is composed of 20 items and 6 categories, was derived through a literature review and a preliminary survey of 11 landscape professionals. An ANP model was established and a survey was conducted among 30 landscape practitioners to determine the weight of priorities considering the criteria. The results of ANP showed that the categories of site selection, preservation and health, and convenience had high priorities while materials had the lowest importance score. For the assessment items, a monitoring plan was the highest importance, followed by cultural/ historic preservation, management cost reduction, and natural ground areas. Despite the difficulties in quantifying landscape achievements, most respondents agreed that there needs to be an evaluation system for landscape performance in order to assure the quality and sustainability of landscape development. More research and discussion are needed to develop an assessment system for landscape performance that is applicable to Korean context.

Analysis of Preservice Chemistry Teachers' Modelling Ability and Perceptions in Science Writing for Audiences of General Chemistry Experiment Using Argument-based Modeling Strategy (논의-기반 모델링 전략을 이용한 일반화학실험에서 글쓰기 대상에 따른 예비화학교사들의 모델링 능력 및 모델링에 대한 인식 분석)

  • Cho, Hye Sook;Kim, HanYoung;Kang, Eugene;Nam, Jeonghee
    • Journal of the Korean Chemical Society
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    • v.63 no.6
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    • pp.459-472
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    • 2019
  • The purpose of this study was to investigate the effect of science writing for different audiences on preservice chemistry teachers' chemistry concept understanding and modeling ability in general chemistry experiment activities using Argument-based Modeling (AbM) strategy. And we also examined preservice chemistry teachers' perceptions of modeling in different audience groups. The participants of the study were 18 university students in the first grade of preservice chemistry teachers taking a general chemistry experiment course. They completed eleven topics of general chemistry experiment using argument-based modeling strategy. The understanding of chemistry concept was compared with the effect size of pre- and post-chemistry concept test scores. To find out modeling ability, we analyzed level of model by each preservice chemistry teacher. Analytical framework for the modeling ability was composed of three elements, explanation, representation, and communication. The questionnaire was conducted to check up on preservice chemistry teacher's recognition of modeling. The result of analyzing the effect of modeling for different audience on the understanding of chemistry concept and modeling ability, the preservice chemistry teachers' were found to be more effective when the level of audience was low. There was no difference in the recognition of modeling between the groups for audience. However, we could confirm that the responses of preservice chemistry teachers are changed in concrete when they have an experience in succession on modeling.

Analysis of Data Characteristics by UAV LiDAR Sensor (무인항공 LiDAR 센서에 따른 데이터 특성 분석)

  • Park, Joon-Kyu;Lee, Keun-Wang
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.5
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    • pp.1-6
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    • 2020
  • UAV (Unmanned Aerial Vehicles) are used widely for military purposes because they are more economical than general manned aircraft and satellites, and have easy access to the object. Recently, owing to the development of IT technology, UAV equipped with various sensors have been released, and their use is increasing in a wide range of fields, such as surveying, agriculture, meteorological observation, communication, broadcasting, and sports. An increasing number of studies and attempts have made use of it. On the other hand, existing research was related mostly to photogrammetry, but there has been a lack of analytical research on LiDAR (Light Detection And Ranging). Therefore, this study examined the characteristics of a UAV LiDAR sensor for the application of a geospatial information field. In this study, the performance of commercialized LiDAR sensors, such as the acquisition speed and the number of echoes, was investigated, and data acquisition and analysis were conducted by selecting Surveyor Ultra and VX15 models with similar accuracy and data acquisition distances. As a result, a DSM of each study site was generated for each sensor, and the characteristics of data density, precision, and acquisition of ground data from vegetation areas were presented through comparison. In addition, the UAV LiDAR sensor showed an accuracy of 0.03m ~ 0.05m. Hence, it is necessary to select equipment considering the characteristics of data for effective use. In the future, the use of UAV LiDAR may be suggested if additional data can be obtained and analyzed for various areas, such as urban areas and forest areas.