• 제목/요약/키워드: ITs Performance Index

검색결과 676건 처리시간 0.026초

Structural Optimization of a Thick-Walled Composite Multi-Cell Wing Box Using an Approximation Method

  • Kim, San-Hui;Kim, Pyung-Hwa;Kim, Myung-Jun;Park, Jung-sun
    • 항공우주시스템공학회지
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    • 제15권2호
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    • pp.1-9
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    • 2021
  • In this paper, a thickness compensation function is introduced to consider the shear deformation and warping effect resulting from increased thickness in the composite multi-cell wing box. The thickness compensation function is used to perform the structure optimization of the multi-cell. It is determined by minimizing the error of an analytical formula using solid mechanics and the Ritz method. It is used to define a structural performance prediction expression due to the increase in thickness. The parameter is defined by the number of spars and analyzed by the critical buckling load and the limited failure index as a response. Constraints in structural optimization are composed of displacements, torsional angles, the critical buckling load, and the failure index. The objective function is the mass, and its optimization is performed using a genetic algorithm.

New reliability framework for assessment of existing concrete bridge structures

  • Mahdi Ben Ftima;Bruno Massicotte;David Conciatori
    • Structural Engineering and Mechanics
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    • 제89권4호
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    • pp.399-409
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    • 2024
  • Assessment of existing concrete bridges is a challenge for owners. It has greater economic impact when compared to designing new bridges. When using conventional linear analyses, judgment of the engineer is required to understand the behavior of redundant structures after the first element in the structural system reaches its ultimate capacity. The alternative is to use a predictive tool such as advanced nonlinear finite element analyses (ANFEA) to assess the overall structural behavior. This paper proposes a new reliability framework for the assessment of existing bridge structures using ANFEA. A general framework defined in previous works, accounting for material uncertainties and concrete model performance, is adapted to the context of the assessment of existing bridges. A "shifted" reliability problem is defined under the assumption of quasi-deterministic dead load effects. The overall exercise is viewed as a progressive pushover analysis up to structural failure, where the actual safety index is compared at each event to a target reliability index.

Preparation and Performance Analysis of Ophthalmic Polymer Using SWCNT and SWCCNT

  • Shin, Su-Mi;Sung, A-Young
    • 한국재료학회지
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    • 제29권12호
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    • pp.735-740
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    • 2019
  • The purpose of this study is to fabricate an ophthalmic lens by copolymerizing two types of carbon nanotubes and hydrophilic hydrogel lens materials, and to investigate its application as an ophthalmic lens material by analyzing its physical properties and antimicrobial effect. For polymerization, HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate), a crosslinking agent, and AIBN (azobisisobutyronitrile), an initiator, are used as a basic combination, and a single-walled carbon nanotube and a single-walled, carboxylic-acid-functionalized carbon nanotube are used as additives. To analyze the physical properties, the water content, refractive index, breaking strength, and antimicrobial effect of the fabricated lenses are measured. The fabricated lenses satisfies all the basic properties of the basic hydrogel ophthalmic lens. The water content increases with increasing amount of additive and decreases with addition of 0.2 % ratio of nanoparticles. The refractive index is inversely proportional to the water content result. As a result of the antimicrobial test of the fabricated lens, the addition of carbon nanotubes shows an excellent antimicrobial effect. Therefore, it is considered that the fabricated lens can be applied as a functional material for basic ophthalmic hydrogel lenses.

주철근 겹침이음 및 보강된 RC교각의 이력거동 (Hysteretic Behavior of Retrofitted RC Bridge Piers with Lap Spliced Longitudinal Steels)

  • 이대형;정영수;박창규;박진영;송희원
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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    • pp.121-126
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    • 2003
  • The objective of this research is to evaluate of seismic performance for reinforced concrete bridge piers with lap splices of longitudinal reinforcement steels using predicting of nonlinear hysteric behavior. For the purpose, enhanced analytical trilinear hystretic model has been proposed to simulate the force-displacement hysteretic curve of RC bridge piers under repeated reversal loads. The moment capacity and corresponding curvature in the plastic hinge have been determined, and the enhanced hysteretic behavior model by five different kinds of branches has been proposed for modeling the stiffness variation of RC section under cyclic loading. The strength and stiffness degradation index are introduced to compute the hysteretic curve for various confinement steel ratios, In addition, the modified curvature factor has been introduced to forecast of seismic performance of longitudinal steel lap spliced and retrofitted specimens. The results of this research will be useful to predict of seismic performance for longitudinal steel with lap spliced and its retrofitted specimens.

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함정의 작전중 항해 안전성에 관한 종합 평가 (An Integrated Evaluation of Navigational Safety for Navel Vessels)

  • 공길영
    • 한국국방경영분석학회지
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    • 제24권1호
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    • pp.132-145
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    • 1998
  • The seakeeping performance can be defined as the ability of a ship to go to sea, and successfully and safely execute its missions even in adverse environmental conditions. From the viewpoint of safe operation, it is primarily important to estimate the seakeeping performance of a ship in a seaway. A method of evaluating navigational safety is presented by means of the integrated seakeeping performance index(ISPI) by measuring only vertical acceleration. Judgement of dangerousness is carried out for two types of naval vessels in applying the involuntary speed losses. The used models for computer simulation are Lpp 175m light aircraft carrier and Lpp 93m frigate. In developing the practical evaluation system of navigational safety, it is expected to be useful to solve the difficulties in measuring factors by sensors. The results are also useful for developing the optimum type of naval vessels by applying at the initial design phase.

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천공 바닥마감재의 유한요소법을 통한 다분야통합설계 (Multidisciplinary Design of Floor Plates with Holes Through Finite Element Method)

  • 유홍희;이창근;유홍걸;서석
    • 한국소음진동공학회논문집
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    • 제13권2호
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    • pp.144-150
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    • 2003
  • Pleasantness or quietness becomes one of the most important factors for residential and office building designs recently. Especially for apartments, the noise generated by falling objects becomes a sensitive issue these days. To overcome the problem of the impact noise in apartments, the floor design has been changed. To reduce the transmissibility of the noise. composite floor structures ate devised and implemented for the construction of apartments. In this paper. the noise reduction) performance of a composite floor plate with holes is analyzed. Computational models for the structures are developed and its Performance is evaluated by using the finite element method. The results show that the noise can be significantly reduced with the multi-layer composite floor plates with holes.

퍼지 추론 방법을 이용한 퍼지 동정과 유전자 알고리즘에 의한 이의 최적화 (Fuzzy Identification by means of Fuzzy Inference Method and its Optimization by GA)

  • 박병준;박춘성;안태천;오성권
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 하계학술대회 논문집 B
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    • pp.563-565
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    • 1998
  • In this paper, we are proposed optimization method of fuzzy model in order to complex and nonlinear system. In the fuzzy modeling, a premise identification is very important to describe the charateristics of a given unknown system. Then, the proposed fuzzy model implements system structure and parameter identification, using the fuzzy inference method and genetic algorithms. Inference method for fuzzy model presented in our paper include the simplified inference and linear inference. Time series data for gas furance and sewage treatment process are used to evaluate the performance of the proposed model. Also, the performance index with weighted value is proposed to achieve a balance between the results of performance for the training and testing data.

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진화 프로그램을 이용한 퍼지 클러스터링 (Fuzzy Clustering using Evolution Program)

  • 정창호;임영희;박주영;박대희
    • 한국정보과학회논문지:소프트웨어및응용
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    • 제26권1호
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    • pp.130-130
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    • 1999
  • In this paper, we propose a novel design method for improving performance of existing FCM-type clustering algorithms. First, we define the performance measure which focuses on bothcompactness and separation of clusters. Next, we optimize this measure using evolution program.Especially the proposed method has following merits: ① using evolution program, it solves suchproblems as initialization, number of clusters, and convergence to local optimum ② it reduces searchspace and improves convergence speed of algorithm since it represents chromosome with possiblepotential centers which are selected possible candidates of centers by density measure ③ it improvesperformance of clustering algorithm with the performance index which embedded both compactnessand separation Properties ④ it is robust to noise data since it minimizes its effect on center search.

Design and Implementation of a Simulation Framework for Wireless Data Broadcasting based on Data ID Space Partition

  • Im, Seokjin
    • International journal of advanced smart convergence
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    • 제7권4호
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    • pp.10-18
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    • 2018
  • For the information services supporting requests of data items from a great number of mobile clients, wireless data broadcasting is an effective way because it can accommodate any number of clients. In the wireless data broadcasting, various air indexing schemes and data scheduling schemes have been developed in order to enable the clients to access their desired data items efficiently. The broadcasting system needs a method to simulate newly designed air indexing and scheduling schemes of the system, and to evaluate the performance parameters of the schemes. In this paper, we design an expandable and efficient simulation framework for the wireless data broadcasting based on the partition of data ID space. The framework can adopt regular and irregular space partition and evaluate various performance parameters of the broadcasting system. We implement a testbed of the broadcasting system using the framework, that adopts IIP, GDI and EXP as its air indexing schemes. We simulate the system using the testbed and evaluate the performance parameters of the system. Thus, we show the efficiency and expandability of the designed and implemented framework.

국방물자정보시스템 성능개선 사업평가에 대한 사례 (A Case on the Evaluation of the Information System Project to Enhance the Performance of DIMS(Defense Material Information System))

  • 조성림;임규건;이대철
    • 한국IT서비스학회지
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    • 제11권1호
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    • pp.109-123
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    • 2012
  • There are many evaluation models to measure the informatization level of an organization and information system project in the ministry of National Defense of Korea. A information system has to keep up with the environment change as well as the advanced recent information technology (IT). Therefore, the evaluation of an information system project to enhance the performance of the information system should be different from the existing evaluation methods. This study suggests an evaluation case of information system projects to enhance the performance of an information system. In order to achieve the objective of this study, the following steps are taken. First, it reviews the background and the scope of the project to enhance the performance of the Defense Material Information System (DMIS). And it sets up the evaluation logic and develops performance indexes. Then it applies these newly developed performance indexes to the information system project and measures the performance. From this study, we found that both the diffusion and the experience accumulation by its continuous use are significant factors in such evaluations.