• Title, Summary, Keyword: Design modifications

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FE model updating method incorporating damping matrices for structural dynamic modifications

  • Arora, Vikas
    • Structural Engineering and Mechanics
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    • v.52 no.2
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    • pp.261-274
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    • 2014
  • An accurate finite element (FE) model of a structure is essential for predicting reliably its dynamic characteristics. Such a model is used to predict the effects of structural modifications for dynamic design of the structure. These modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can't be used for accurate prediction of vibration amplitudes. This paper deals with the basic formulation of damped finite element model updating method and its use for structural dynamic modifications. In this damped damped finite element model updating method, damping matrices are updated along with mass and stiffness matrices. The damping matrices are updated by updating the damping coefficients. A case involving actual measured data for the case of F-shaped test structure, which resembles the skeleton of a drilling machine is used to evaluate the effectiveness of damped FE model updating method for accurate prediction of the vibration levels and thus its use for structural dynamic modifications. It can be concluded from the study that damped updated FE model updating can be used for structural dynamic modifications with confidence.

Geometric Constraint Management for Sweeping and Boolean Operations (스위핑과 불리언 연산에 대한 형상 구속조건 관리)

  • 김웅주;정채봉;김재정
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.4
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    • pp.301-311
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    • 2000
  • For effective part modifications which is necessary in the design process frequently, variational geometric modeling with constraint management being used in a wide. Most variational geometric modeling methods, however, manage just the constraints about sketch elements used for generation of primitives. Thus, not only constraint propagation but also re-build of various modeling operations stored in the modeling history is necessary iota part geometry modifications. Especially, re-build of high-cost Boolean operations is apt to deteriorate overall modeling efficiency abruptly. Therefore, in this paper we proposed an algorithm that can handle all geometric entities of the part directly. For this purpose, we introduced eight type geometric constraints to the various geometric calculations about all geometric entities in sweepings and Boolean operations as well as the existing constraints of the sketch elements. The algorithm has a merit of rapid part geometric modifications through only constraint propagation without rebuild of modeling operations which are necessary in the existing variational geometric modeling method.

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A Study on Residential Modification Demand by Elderly Lived in Detached Housing - Focusing on Application of Ubiquitous Home Services - (단독주택 거주 노인의 주택개조 요구에 관한 연구 - 유비쿼터스 홈 서비스 적용을 중심으로 -)

  • Ha, Hae-Hwa;Kwon, Oh-Jung
    • Korean Institute of Interior Design Journal
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    • v.21 no.2
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    • pp.141-151
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    • 2012
  • Korea is a fast growing aging society. Growing older population causes various social issues and problems in many aspects. Housing issue is one of them and residential modifications for improving safety and independence for older residents are very important factor for Aging in Place. Under those social circumstances, the purpose of this study was to analyze the residential modification demand by the elderly on the application of ubiquitous home services. Respondents were the residents those who were over 55 years old, were living in a singe detached house and were able to use a computer. The major findings of this study were as follows: the results on current situations and demands for residential modifications showed that respondents already made mean of 4.9 home modification items and wanted to make mean of 12.4 items out of 21 residential modification items. The results on demands for the ubiquitous home services was relatively high(mean 3.82). This study can be an important information which is able to improve the quality of life by providing effective residential modifications for older population to help them ultimately safe, convenient, and independent living.

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A Study of Various Collar of Casual Korean Dress (생활한복의 깃 디자인 기원에 관한 연구)

  • Kwen, Jin;Park, Hea-Ryoung
    • Fashion & Textile Research Journal
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    • v.3 no.3
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    • pp.211-218
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    • 2001
  • In this paper, various shapes of collar of the casual Korean dress at present are analyzed and are also surveyed the origins from which such designs are derived. Collars of the casual Korean dress are to be classified into Round-collar, Mokpan-collar, Dangco-collar, Knife-collar, Baja-collar, Danryoung-transfer-collar, Double-collar, Transfer-collar, and so on. Round-collar, Mokpan-collar, Dangco-collar, Knife-collar, Baja-collar, Danryoung-transfer-collar, Double-collar, Transfer-collar are motivated from the classical types of collar during the dynasty of the Choxian and adopted without any modifications. However, modifications to meet modern sense with the basic motif on the classical types of collar are applied to Transfer-collar where all kinds of collar shapes since ancient times are referred for modifications. In addition, collars such as Double-collar, Hi-neck-collar, which are not found in the classical Korean dress, could be said to be created only for the casual Korean dress From the above, it could be seen that most collars of the casual Korean dress are based on the shapes of the classical Korean dress. Therefore, it could be also confirmed that the casual Korean dress design has its identity originated from the classical Korean dress since the ancient times.

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Improvement of Steering-Wheel Idle Vibration in a Passenger Car using Design Sensitivity Analysis (설계민감도 해석을 이용한 승용차의 스티어링 휠 아이들 진동 개선)

  • 이두호;김명업
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.2
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    • pp.129-137
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    • 2000
  • In the prototype stage of a car developing program, the efficiency of trouble shooting is an important factor to be considered. Structural modifications by the design sensitivity analysis are applied to a steering wheel system for improving the idle vibration of the prototype passenger car. For the design sensitivity analysis, the experimental modal analysis for the steering system attached to a body-in-white is fulfilled and the modal parameters extracted from the experimental data are used to predict the effect of structural modification, The design sensitivity results rank the locations to be reinforced in terms of frequency variation. The modification of steering system according to the sensitivity analysis results shifted the resonant frequency of the system effectively. In addition, the idle test of the car after the structural modifications f steering system shows that the proposed method can reduce vibration of the steering wheel efficiently.

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The effect of semantic, syntactic and lexical factors on the menu selection performance for video cassette recorder operation

  • 이삼수;구자령;이종수;이면우
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • pp.389-394
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    • 1996
  • The product-user interface for consumer electronic products became complex due to the increased variety of functions corresponding to consumer needs. In this study, three types fo design improvement of the menu interface for a video cassette recorder is studied. Three modifications to an existing menu interface was designed using the semantic, the syntactic and the lexical design factors. A series of the validation experiments was performed to test the effect of the three types of task modifications. The results showed that performance time, number of errors and learning effect were improved for all task modification. It also showed that the performance improvement effect of the semantic factors was 8.8%, that of the syntactic factors was 5.9% and that of the lexical factors was 5.6% respectively. It was found out that the performance improvement effect of the semantic design factors were relatively more significant than the syntactic and the lexical design factors.

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System Theoretic Representation of UI System and DEVS Modeling (시스템 형식론에 의한 사용자 인터페이스 시스템 표현과 DEVS 모델링)

  • 김은하;조대호
    • Journal of the Korea Society for Simulation
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    • v.8 no.4
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    • pp.137-154
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    • 1999
  • In this paper, we propose a software design method that will track the effects of modifications in a component to the rest of the components in the design phase. The prediction of the effects due to the design modifications before coding can be a valuable aid for the complex and large software development. Within the method, the target system is represented by the structured I/O system level specification which is one of the system representation level defined by the system theory. Then it is abstracted to the I/O system level. The DEVS (Discrete Event System Specification) model is constructed based on tile I/O system level specification. Finally, the DEVS model is simulated to generate the behavior of the software by the abstract simulator in DEVS simulation environment. As an application, the graphic user interface system of a metal grating production scheduling system is presented.

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Structural modal reanalysis using automated matrix permutation and substructuring

  • Boo, Seung-Hwan
    • Structural Engineering and Mechanics
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    • v.69 no.1
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    • pp.105-120
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    • 2019
  • In this paper, a new efficient method for structural modal reanalysis is proposed, which can handle large finite element (FE) models requiring frequent design modifications. The global FE model is divided into a residual part not to be modified and a target part to be modified. Then, an automated matrix permutation and substructuring algorithm is applied to these parts independently. The reduced model for the residual part is calculated and saved in the initial analysis, and the target part is reduced repeatedly, whenever design modifications occur. Then, the reduced model for the target part is assembled with that of the residual part already saved; thus, the final reduced model corresponding to the new design is obtained easily and rapidly. Here, the formulation of the proposed method is derived in detail, and its computational efficiency and reanalysis ability are demonstrated through several engineering problems, including a topological modification.

Assessment of across-wind responses for aerodynamic optimization of tall buildings

  • Xu, Zhendong;Xie, Jiming
    • Wind and Structures
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    • v.21 no.5
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    • pp.505-521
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    • 2015
  • A general approach of aerodynamic optimization of tall buildings is presented in this paper, focusing on how to best compromise wind issues with other design aspects in the most efficient manner. The given approach is reinforced by establishing an empirical method that can quickly assess the across-wind loads and accelerations as a function of building frequencies, building dimensions, aspect ratios, depth-to-width ratios, and site exposures. Effects of corner modifications, including chamfered corner and recessed corner, can also be assessed in early design stages. Further, to assess the effectiveness of optimization by tapering, stepping or twisting building elevations, the authors introduce a method that takes use of sectional aerodynamic data derived from a simple wind tunnel pressure testing to estimate reductions on overall wind loads and accelerations for various optimization options, including tapering, stepping, twisting and/or their combinations. The advantage of the method is to considerably reduce the amount of wind tunnel testing efforts and speed up the process in finding the optimized building configurations.

Aerodynamic design optimization of an aircraft wing for drag reduction using computational fluid dynamics approach

  • Shiva, Kumar M.R;Srinath, R;Vigneshwar, K;Ravi, Kumar B
    • Wind and Structures
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    • v.31 no.1
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    • pp.15-20
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    • 2020
  • The aircraft industry supports aviation by building aircraft and manufacturing aircraft parts for their maintenance. Fuel economization is one of the biggest concerns in the aircraft industry. The reduction in specific fuel consumption of aircraft can be achieved by a variety of means, simplest and more effective is the one to impose minor modifications in the aircraft main wing or the parts which are exposed to the air flow. This method can lead to a reduction in aerodynamic resistance offered by the air and have a smoother flight. The main objective of this study is to propose geometric design modifications on an existing aircraft wing which acts as a vortex generator and it can reduce the drag and increase lift to drag ratio, leading to lower fuel consumption. The NACA 2412 aircraft wing is modified and designed. Rigorous flow analysis is carried out using computational fluid dynamics based software Ansys Fluent. Results show that saw tooth modification to the main wing shows the best aerodynamic efficiency as compared to other modifications.