• Title/Summary/Keyword: ESSENTIAL ELEMENT

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Simplified model to study the dynamic behaviour of a bolted joint and its self loosening

  • Ksentini, Olfa;Combes, Bertrand;Abbes, Mohamed Slim;Daidie, Alain;Haddar, Mohamed
    • Structural Engineering and Mechanics
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    • v.55 no.3
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    • pp.639-654
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    • 2015
  • Bolted joints are essential elements of mechanical structures and metal constructions. Although their static behaviour is fairly well known, their dynamic behaviour due to shocks and vibrations has been less studied, because of the large size of the finite element models needed for a detailed simulation. This work presents four different simplified models suitable for studying the dynamic behaviour of an elementary bolted joint. Three of them include contact elements to allow sliding of the screw head and the nut on the assembled parts, and the last one allows rotation between screw and nut. A penalty approach based on the Coulomb friction model is used to model contact. The results show that these models effectively represent the dynamic behaviour, with different accuracy depending on the model details. The last model simulates the self loosening of a bolt subjected to transversal vibrations.

Study on Design of Digital filter by 2's Complement Representation using Bidirectional algorithm (양방향 알고리즘을 이용한 2의 보수 표현 기법에 의한 디지털 필터의 설계에 관한 연구)

  • LEE, Youngseock
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.2 no.1
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    • pp.37-42
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    • 2009
  • The digital filter is essential element in digital signal processing area. It needs a high computational burden caused by multiplying and adding. The multiplier in digital filter is a dominant element, which occupies an wide area at the field of VLSI design, needs high power-consuming and also decides critical path that affects to filter performance. In this paper we proposed the simultaneous transform method which is represented 2's complementary representation to CSD and MSD representation to solve a complexity problem and to improve a computational speed. The performance of proposed method was implemented in VHDL and applied to an digital filters, was evaluated the decreasing of critical path delay.

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Temperature increase of the spindle bearing system having a gear on the bearing span (베어링 스팬상에 기어구동축을 갖는 스핀들 베어링 시스템의 열특성에 관한 연구)

  • Choi, Jin-kyung;Lee, Dai-Gil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.33-43
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    • 1998
  • High cutting speeds and feeds are essential requirements of a machine tool structure to accomplish its basic function which is to produce a workpiece of the required geometric form with an acceptable surface finish at as high a rate of production as is economically possible. Since the bearings in high speed spindle units are the main heat source of the total cutting system, in this work, the thermal characteristics of the spindle bearing system with a tilting axis were investigated using finite element methods to improve the performance of the spindle bearing system. Based on the theoretical results, a specially designed prototype spindle bearing system has been manufactured. Using the manufactured spindle bearing system, the thermal characteristics were measured. From the comparison of the experimental results with the theoretical ones, it was found that the finite element method predicted well the thermal characteristics of the spindle bearing system.

Development of Mesh Generation Program for the Primary System of Nuclear Power Plant (원자력 주요기기 해석을 위한 자동요소망 생성프로그램 개발)

  • Jang, Dong-Min;Kim, Yeong-Jin;Choe, Seong-Nam;Seo, Myeong-Won;Jang, Gi-Sang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.2 s.173
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    • pp.386-393
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    • 2000
  • Fracture mechanics analysis (FMA) is an essential work for integrity evaluation of nuclear power plant. The flaws inspected by In-Service Inspection(ISI) should be confirmed by FMA for the decision of the operation status of stop or continuance. The basic data for FMA are the stress of the interested area. The purpose of this research is to develop a system which can obtain stress data efficiently based on various database. Mesh generation program generates mesh using MSC/PATRAN and provides input file for finite element analysis according to the databases (shape, dimension, transient and material). The stress data from the finite element analysis are stored to be stress database so that it can be applied to FMA. As an example, the system developed by this study is applied to pressurizer nozzle and confirmed to be a useful tool for efficient FMA.

Element Design of Balancing Shaft for Reducing the Vibration in Engine Module (엔진진동 저감을 위한 밸런싱샤프트의 요소설계 기법 연구)

  • Kim, Chan-Jung;Beak, Gyoung-Won;Lee, Bong-Hyun;Kim, Gi-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.615-620
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    • 2005
  • Vibration in Engine module could be reduced by introducing a balance shaft module which has one or more unbalanced rotors. The unbalanced rotor is unbalanced in one direction that act as a opposite direction of the inertia force or moment triggered by engine component so that the largest order factor in vibration is efficiently decreased The ability of balance shaft to reduce the order element of engine component is investigated by a vehicle testing that is focused on comparing the vibration with balance shaft to that of without balance shaft. One of the commonly adapted balance shaft is tested by modal scheme for indemnifying the dynamic characteristics and an, the modal information is used for a clue to design the balance shaft module. The essential equation deriving the design parameters of unbalanced rotor is also presented for two cases, 3 in-ling and 4 in-ling cylinder model. Finally, the overall design process is explained with flow chart.

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Design of Miniaturized Wireless Sensor Node Using System-on-Chip (SoC를 이용한 소형 무선 센서 노드 설계)

  • Kim, Hyun-Joong;Yang, Hyun-Ho
    • Proceedings of the KAIS Fall Conference
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    • 2009.12a
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    • pp.190-193
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    • 2009
  • The most essential element in wireless sensor network is wireless sensor node which collects environmental information and transmits it to the user application systems. Recently, due to the technological advancement, wireless sensor nodes are become smaller, more intelligent and less power consuming. Especially, SoC(System-on-Chip) technology, which unifies the MCU, RF module, memory and other element inside one chip, plays an important part for miniaturization of sensor node, hence reduces the manufacturing expenses. In this paper, we have designed a miniaturized wireless sensor node for wireless sensor network using commercial SoC technology and discussed about some application scenario and additional considerations.

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A Study on The Space Depth For Hospital Architecture Planning Focused on System (체계 중심 병원건축계획을 위한 공간 깊이에 관한 연구)

  • Kim, Eun-Seok;Yang, Nae-Won
    • Korean Institute of Interior Design Journal
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    • v.24 no.6
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    • pp.221-228
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    • 2015
  • This study aims to define concepts on Hospital Design Focused on System to respond to the development and change by comparing general design methods of the General hospital architecture in Korea and analyze elements suitable to concepts on Hospital Design Focused on System in the General hospital architecture through examining the transformation of General hospitals in Korea. Essential architectural elements composing the Hospital Design Focused on System are as follows. First of all, the elements which can react to development of hospital architecture are HOSPITAL STREET and site situation. Secondly, core, equipment shaft, column, MAIN STREET and air handling unit room are elements of great importance as the location of these elements determines the dimensions and scale of the space which hospital functions are assigned to. Third, the area in regard to the rate of change is formed by MAIN STREET, which is the primary element, and envelope. The depth between MAIN STREET and envelope is defined as space depth. The flexible area is determined depending on this space depth and thus how to set up this flexible area determines the degree of readiness in responding to the change.

Instrumentation and Structural Health Monitoring of Bridges (교량구조물의 헬스모니터 링을 위한 진동계측)

  • 김두기;김종인;김두훈
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.11 no.5
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    • pp.108-122
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    • 2001
  • As bridge design is advancing toward the performance-based design. it becomes increasingly important to monitor and re-evaluate the long-term structural performance of bridges. Such information is essential in developing performance criteria for design. In this research. sensor systems for long-term structural performance monitoring have been installed on two highway bridges. Pre1iminary vibration measurement and data analysis have been performed on these instrumented bridges. On one bridge, ambient vibration data have been collected. based on which natural frequencies and mode shapes have been extracted using various methods and compared with those obtained by the preliminary finite element analysis. On the other bridge, braking and bumping vibration tests have been carried out using a water truck In addition to ambient vibration tests. Natural frequencies and mode shapes have been derived and the results by the breaking and bumping vibration tests have been compared. For the development of a three dimensional baseline finite element model, the new methodology using a neural network is proposed. The proposed one have been verified and applied to develop the baseline model of the bridge.

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Study on Development Process of Furniture Design Class by Applying Role-playing (Role-playing을 적용한 가구 디자인 수업 개발 사례 연구)

  • In, Chi Ho
    • Journal of the Korea Furniture Society
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    • v.27 no.4
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    • pp.280-290
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    • 2016
  • In design education enhancement of design methodology and creativity can be stimulated through taking on several creative roles within an interactive and enjoyable studio course. To overcome blocks to creativity I developed a intermediate course, 'Furniture Design Studio I' at the sophomore advanced level course. Inventive thinking and a sense of aesthetic are the essential element for all studnets to grow as a professional designer. And to develop their creative thinking skill I introduced a system that utilizes each element into a role-playing type of projects. Students will be able to demonstrate their underlying creativity in a more open environment. Instead of stressing to solve a lot of complicate issues, the main focus is to allow freedom of expression and creativity. Role-playing are executed in a design studio environment rather than in a psychodrama situation. There are two different type of role-playing : Inventor and Designist (Designer + Artist). Students will be able to work in groups, incorporate problem solving into their projects and concentrate on more personal creative form developments. Through this process, students will enhance their problem solving abilities and broaden their scope for innovation. Thus increases the student's participation and creativity. Investigating the problems of domestic design education through these sort of special programs and developing systems that enhance creativity based on the results and the process methods.

Numerical simulation of concrete confined by transverse reinforcement

  • Song, Zhenhuan;Lu, Yong
    • Computers and Concrete
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    • v.8 no.1
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    • pp.23-41
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    • 2011
  • The behaviour of concrete confined by transverse reinforcement is a classical topic. Numerous studies have been conducted to establish the stress-strain relationships for concrete under various confining reinforcement arrangements. Many empirical and semi-empirical formulas exist. Simplified analytical models have also been proposed to evaluate the increase in the strength and ductility of confined concrete. However, relatively few studies have been conducted to utilise advanced computational models for a realistic simulation of the behaviour of concrete confined by transverse reinforcement. As a matter of fact, high fidelity simulations using the latest numerical solvers in conjunction with advanced material constitutive models can be a powerful means to investigating the mechanisms underlying the confining effects of different reinforcement schemes. This paper presents a study on the use of high fidelity finite element models for the investigation of the behaviour of concrete confined by stirrups, as well as the interpretation of the numerical results. The development of the models is described in detail, and the essential modelling considerations are discussed. The models are then validated by simulating representative experimental studies on short columns with different confining reinforcement schemes. The development and distribution of the confining stress and the subsequent increase in the axial strength are examined. The models are shown to be capable of reproducing the behaviour of the confined concrete realistically, paving a way for systematic parametric studies and investigation into complicated confinement, load combination, and dynamic loading situations.