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이재옥(Jae-Ohk Lee),김병주(Byung-Joo Kim),박진수(Jinsoo Park),정성수(Sung-Soo Jung) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The authors have investigated the bolt tightening mechanism of connecting rod assembly for a 4-stroke medium speed diesel engine. The paper presents the results of the investigation on two different types of bolts: studs and tapped bolts. These are fastened by hydraulic tightening devices and torque wrenches, respectively. Strain measurement, numerical analysis, tightening test and strength test have been carried out so as to verify the mechanical behavior and properties of the bolts and also to investigate the characteristics of the tightening methods. During the hydraulic tightening of the studs, it was observed that about 15% of the hydraulic pressure was not transferred to the stud pretension. As for the tapped bolts, a number of bolt tightening tests have been conducted under various conditions considering coating, lubrication and tightened materials. Friction coefficients and the effect of phosphated coating were investigated.
신뢰성기반 최적설계에서 수치적 안정성과 효율성의 개선을 위해 수정된 Single Loop Single Vector 방법
김봉재,이재옥,양영순,Kim, Bong-Jae,Lee, Jae-Ohk,Yang, Young-Soon 한국전산구조공학회 2005 한국전산구조공학회논문집 Vol.18 No.1
SLSV(single loop single vector)방법은 신뢰성기반 최적설계(reliability-based design optimization, RBDO)에서 중첩된 반복과정을 제거함으로써 최적설계의 과도한 계산비용 문제에 대한 해결책을 제시하고 있지만, 종종 수렴하지 못하거나 잘못된 해가 얻어지는 등의 불안정성, 부정확성 문제를 가지고 있어 그 활용이 제한적이다. 본 논문에서는 수정된 HMV(hybrid mean value)방법, Inactive Design, Active MPP(most probable point) Design의 적용을 통해 SLSV방법에 있어서 안정성과 효율성을 효과적으로 개선시킬 수 있는 수정된 SLSV방법을 제안하였고 또한 다양한 예제를 통해 수정된 SLSV방법의 유용성을 검증하였다. SLSV (single loop single vector) method is to solve the excessive computational cost problem in RBDO (reliability-based design optimization) by decoupling the nested iteration loops. However, the practical use of SLSV method to RBDO case is limited by the instability or inaccuracy of the method since it often diverges or converges to a wrong solution. Thus, in this paper, a new modified SLSV method is proposed. This method improves its convergence capability effectively by utilizing Inactive Design and Active MPP Design together with modified HMV (hybrid mean value) method. The usefulness of the proposed method is also verified through numerical examples.
유연 다물체 동역학을 이용한 셔블형 굴삭기의 부하작업 시뮬레이션
김성용(Seong-Yong Kim),이재옥(Jae-Ohk Lee),김병주(Byung-Joo Kim),백상재(Ssang-Jae Baek) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
It is getting more and more common to design a new construction equipment model with much advanced performance on the basis of finite element analysis. It is not easy to obtain reliable structural responses such as displacement and stress from numerical analysis as the loading and boundary conditions of construction equipments are not only complicated but continuously changing during their operation. This paper shows that the up-to-date flexible multi-body dynamics(FMBD) could be one of the most powerful solutions for the analysis of moving equipments. The structural behavior of a shovel-typed hydraulic excavator developed by Hyundai Heavy Industries has been numerically simulated during working conditions. It was observed that there was a good agreement of its structural responses between the field test and the FMBD simulation.
김병주(Byung-Joo Kim),이재옥(Jae-Ohk Lee),박진수(Jinsoo Park),김세락(SeLak Kim) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
The cylinder cover stud of low-speed marine diesel engine is more than just a stud. It is a large structural element occasionally weighing over 200 ㎏ used for assembling the combustion chamber components. Therefore, to understand the structural behavior of the stud and design it safely is quite important considering a catastrophic failure which can be arisen from an inadequate use of it. In this paper, the analysis results of the structural behavior of the stud is introduced. Strain measurement results compared with FE analysis results are summarized. The results showed that 1) the stud stress increased with engine operating load, 2) the maximum stress amplitude was about 10 ㎫ which is far smaller than the stud's fatigue strength of 61 ㎫, 3) the stress ratio is higher than 0.9 and the stud's load factor is about 20 %, and 4) about 7 % of initial pressure tightening load was reduced while changing to a nut tightened condition.
박윤기(Yun-Ki Park),이재옥(Jae-Ohk Lee),하우일(Woo-Il Ha),김병주(Byung-Joo Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The cabin of industrial machine must satisfy the safety regulation based on ISO to ensure the safety of the operator in case of accident. In order to save the expenses to test the cabin, F.E.A could be used to predict the safety test results and to modify the design of the cabin. In this study, the safety of the cabin of a wheeled loader was evaluated by F.E.A. and an appropriate bracket type was selected by simple joint tests. Finally, the safety test of the cabin of a wheeled loader was performed.