• Title/Summary/Keyword: Mounting method

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Design Methodology of Automotive Wheel Bearing Unit with Discrete Design Variables (이산 설계변수를 포함하고 있는 자동차용 휠 베어링 유닛의 설계방법)

  • 윤기찬;최동훈
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.1
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    • pp.122-130
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    • 2001
  • In order to improve the efficiency of the design process and the quality of the resulting design, this study proposes a design method for determining design variables of an automotive wheel-bearing unit of double-row angular-contact ball bearing type by using a genetic algorithm. The desired performance of the wheel-bearing unit is to maximize system life while satisfying geometrical and operational constraints without enlarging mounting spae. The use of gradient-based optimization methods for the design of the unit is restricted because this design problem is characterized by the presence of discrete design variables such as the number of balls and standard ball diameter. Therefore, the design problem of rolling element bearings is a constrained discrete optimization problem. A genetic algorithm using real coding and dynamic mutation rate is used to efficiently find the optimum discrete design values. To effectively deal with the design constraints, a ranking method is suggested for constructing a fitness function in the genetic algorithm. A computer program is developed and applied to the design of a real wheel-bearing unit model to evaluate the proposed design method. Optimum design results demonstrate the effectiveness of the design method suggested in this study by showing that the system life of an optimally designed wheel-bearing unit is enhanced in comparison with that of the current design without any constraint violations.

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Measurement and Correction of PCB Alignment Error for Screen Printer Using Machine Vision (2) (머신비전을 이용한 PCB 스크린인쇄기의 정렬오차측정 및 위치보정 (2))

  • 신동원
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.6
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    • pp.96-104
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    • 2003
  • This paper presents the measurement and correction method of PCB alignment errors for PCB screen printer. Electronic equipment is getting smaller and yet must satisfy high performance standard. Therefore, there is a great demand for PCB with high density. However conventional PCB screen printer doesn't have enough accuracy to accommodate the demand for high-resolution circuit pattern and high-density mounting capacity of electronic chips. It is because the alignment errors of PCB occur when it is loaded to the screen printer. Therefore, this study focuses on the development of the system which is able to measure and correct alignment errors with high-accuracy. An automatic optical inspection part measures the PCB alignment errors using machine vision, and the high-accuracy 3-axis stage makes correction for these errors. This system used two CCD cameras to get images of two fiducial marks of PCB. The centers of fiducial marks are obtained by using moment, gradient method. The first method is calculating the centroid by using first moment of blob, and the latter method is calculating the center of the circle whose equation is obtained by curve-fitting the boundaries of fiducial mark. The operating system used to implement the whole set-up is carried in Window 98 (or NT) environment. Finally we implemented this system to PCB screen printer.

A Comparative Analysis between Rigorous and Approximate Approaches for LiDAR System Calibration

  • Kersting, Ana Paula;Habib, Ayman
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.6_2
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    • pp.593-605
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    • 2012
  • LiDAR systems provide dense and accurate topographic information. A pre-requisite to achieving the potential accuracy of LiDAR is having a proper system calibration, which aims at estimating all the systematic errors in the system measurements and the mounting parameters relating the different components. This paper presents a rigorous and two approximate methods for LiDAR system calibration. The rigorous approach makes use of the LiDAR equation and the system raw measurements. The approximate approaches utilize simplified LiDAR equations using some assumptions, which allow for less strict requirements regarding the raw measurements. The first presented approximate method, denoted as quasi-rigorous, assumes that we are dealing with a vertical platform (i.e., small pitch and roll angles). This method requires time-tagged point cloud and trajectory position data. The second approximate method, denoted as simplified, assumes that we are dealing with parallel strips, vertical platform, and minor terrain elevation variations compared to the flying height above ground. Such method can be performed using the LiDAR point cloud only. Experimental results using a real dataset, whose characteristics deviate to some extent from the utilized assumptions in the approximate methods, are presented to provide a comparative analysis of the outcome from the introduced methods.

A Study on Improving Reliability of Durability Life Estimation for Excavator Fuel Tank Mounting Using Equivalent S-N Curve Method (등가 S-N 선도 모형에서의 굴착기 연료탱크 마운팅부 내구수명 예측 신뢰성 향상 방안 연구)

  • Lee, Sung-Won;Jeong, Jin-Wook;Kim, Seong-Jae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.5
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    • pp.17-26
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    • 2021
  • It is challenging to estimate the fatigue life of construction equipment consisting of a welded joint using field structure test owing to the uncertainty of the S-N curve. IIW recommends different S-N curves for various welded joint types. However, there is no way to define an appropriate curve considering complex design shape and strain gauge characteristics. This paper proposes an equivalent S-N curve method based on the relationship between IIW effective notch stress and virtual stress using finite element analysis. Moreover, a case study was conducted for the excavator fuel tank. The proposed method is expected to enhance accuracy and consistency in calculating the fatigue life for the welded structure of construction equipment.

Simulator of Accuracy Prediction for Developing Machine Structures (기계장비의 구조 특성 예측 시뮬레이터)

  • Lee, Chan-Hong;Ha, Tae-Ho;Lee, Jae-Hak;Kim, Yang-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.28 no.3
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    • pp.265-274
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    • 2011
  • This paper presents current state of the prediction simulator of structural characteristics of machinery equipment accuracy. Developed accuracy prediction simulator proceeds and estimates the structural analysis between the designer and simulator through the internet for convenience of designer. 3D CAD model which is input to the accuracy prediction simulator would simplified by the process of removing the small hole, fillet and chamfer. And the structural surface joints would be presented as the spring elements and damping elements for the structural analysis. The structural analysis of machinery equipment joints, containing rotary motion unit, linear motion unit, mounting device and bolted joint, are presented using Finite Element Method and their experiment. Finally, a general method is presented to tune the static stiffness at a rotation joint considering the whole machinery equipment system by interactive use of Finite Element Method and static load experiment.

Design of a Rule-Based Solution Based on MFC for Inspection of the Hybrid Electronic Circuit Board (MFC 기반 하이브리드 전자보오드 검사를 위한 규칙기반 솔루션 설계)

  • Ko Yun-Seok
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.9
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    • pp.531-538
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    • 2005
  • This paper proposes an expert system which is able to enhance the accuracy and productivity by determining the test strategy based on heuristic rules for test of the hybrid electronic circuit board producted massively in production line. The test heuristic rules are obtained from test system designer, test experts and experimental results. The guarding method separating the tested device with circumference circuit of the device is adopted to enhance the accuracy of measurements in the test of analog devices. This guarding method can reduce the error occurring due to the voltage drop in both the signal input line and the measuring line by utilizing heuristic rules considering the device impedance and the parallel impedance. Also, PSA(Parallel Signature Analysis) technique Is applied for test of the digital devices and circuits. In the PSA technique, the real-time test of the high integrated device is possible by minimizing the test time forcing n bit output stream from the tested device to LFSR continuously. It is implemented in Visual C++ computer language for the purpose of the implementation of the inference engine using the dynamic memory allocation technique, the interface with the electronic circuit database and the hardware direct control. Finally, the effectiveness of the builded expert system is proved by simulating the several faults occurring in the mounting process the electronic devices to the surface of PCB for a typical hybrid electronic board and by identifying the results.

Effects of Specimen Preparation Method and Contact Resistance on the Formation of Anodizing Films on Aluminum Alloys (시편의 준비 방법 및 접촉저항이 알루미늄 합금의 아노다이징 피막 형성에 미치는 영향)

  • Moon, Sungmo
    • Journal of the Korean institute of surface engineering
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    • v.53 no.1
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    • pp.29-35
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    • 2020
  • In this study, five different specimen preparation methods were introduced and their advantages and disadvantages were presented. One of them, an epoxy mounting method has advantages of constant exposure area, ease of surface preparation without touching the specimen surface during polishing or cleaning, use of small amount of material and ease of specimen reuse by polishing or etching. However, in order to eliminate unexpected errors resulting from preferable reaction at the specimen/epoxy interface and contact resistance between the specimen and copper conducting line for electrical connection, it is recommended to cover the wall side of the specimen with porous anodic oxide films and to remain the contact resistance lower than 1 ohm. The increased contact resistance between the specimen and Cu conducting line appeared to result in increases of anodizing voltage and solution temperature during anodizing by which thickness and hardness of anodizing film on Al2024 alloy were drastically decreased and color of the films became more brightened.

A Study on the Optimal Design of Gas Spring for Vehicle (자동차용 GAS SPRING의 최적 설계에 관한 연구)

  • 김영범
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.11
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    • pp.39-45
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    • 1998
  • Gas springs have been widely used in motor vehicles as well as in most areas of industry. Instead of coil springs, these gas springs are easily opreated to open(extension process) or close (compression process) the doors because $N_2$ gas with high pressure and oil are charged in tube. Most of manufacturers are using the trial & error method in order to decide its specification(reaction force, damping force), which tends to waste time and money. Therefore, gas springs have been improved by properly changing the control pressure of $N_2$ Gas with its mounting location and weight to maximize its effect and to minimize its space. Although it has been researched on damping structure to minimize impact which is applied to vehicle when its back door is fully opened, the characteristics of damping structure are not known clearly. There(ore, this paper will not only clearly define the effect of important factors(open & close force)for gas springs through theoretical analysis but also provide optimum design specification through development of program to avoid traditional method of specification determination such as the trail It error method which is widely used in whole industries including automotive industry.

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Estimate of package crack reliabilities on the various parameters using taguchi's method (다꾸찌방법을 사용한 여러변수들이 패키지균열에 미치는 신뢰도 평가)

  • Kwon, Yong-Su;Park, Sang-Sun;Park, Jae-Wan;Chai, Young-Suck;Choi, Sung-Ryul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.6
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    • pp.951-960
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    • 1997
  • Package crack caused by the soldering process in the surface mounting plastic package is evaluated by applying the maximum energy release rate criterion. It could be shown that the crack propagation from the lower edge of the ie pad is easily occurred at the maximum temperature during the soldering process, where the pressure acting on the crack surface is assumed by the saturated vapor pressure at maximum temperature. The package crack formation depends on various parameters such as chip size, relative thickness, material properties, the moisture content and soldering temperature etc. The quantitative measure of the effects of the parameters could be easily obtained by using the taguchi's method which requires only a few kinds of combinations with such parameters. From the results, it could be obtained that the more significant parameters to effect the package reliability are the orders of Young's modulus, die pad size, down set, chip thickness and maximum soldering temperature.

A Study on the Fabrication of Laser-Induced Graphene Humidity Sensor for Mounting on a Disposable Mask (일회용 마스크에 장착을 위한 레이저 기반 그래핀 습도센서 제작에 관한 연구)

  • Lee, Jun-Uk;Shin, Yun-Ji;Yang, Hye-Jeong;Shin, Bo-Sung
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.4_2
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    • pp.693-699
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    • 2020
  • 355nm UV pulse laser is irradiated on the surface of polyimide (PI) by LDW (Laser Direct Writing) method to produce a high sensitivity flexible humidity sensor using a simple one-step process. The LDW method continuously investigates 2-D CAD data using a galvano scanner and an F-lens. This method is non-contact, so it minimizes physical strain on the PI. Laser-induced graphene (LIG) produced by lasers has a high surface area due to its high flexibility and numerous pores and oxidizers compared to conductors. For this reason, it is highly useful as a flexible humidity sensor. The humidity sensor produced in this study was attached to the inside of a mask filter, which has become a hot topic recently, and its applicability was confirmed.The measurement of humidity measured the sensitivity, reactivity, stability and recovery behavior of the sensor by measuring changes in capacitance and resistance.