• 한국산학기술학회논문지
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• 제19권6호
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• pp.581-586
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• 2018

주철 맨홀뚜껑은 제조과정에서 환경오염을 유발하며, 작업환경은 매우 열악하다. 또한, 맨홀 뚜껑의 높이와 도로 표면의 높이가 일치하지 않은 경우에는 많은 불편을 초래하며 안전에도 문제를 야기한다. 본 연구에서는 주철 맨홀뚜껑을 대체할 수 있고, 도로 노면 공사 시 도로 노면 높이와 맨홀 뚜껑의 높이를 동일하게 맞추기 용이한 높이 조절이 가능한 강재 맨홀 뚜껑 구조를 제안하였다. 요구되는 품질 성능을 만족시키기 위한 맨홀 뚜껑의 구조에 대한 설계변수를 파악하기 위하여 구조 해석을 수행하였다. 요구되는 내하중 용량을 만족하는 맨홀뚜껑을 제작하기 위하여 ㄷ자 모양의 보강대에 대하여 최적 설계를 수행하였다. 높이조절부의 원통과 하부 프레임 원통은 강판을 굽힘 가공하여 원형의 형상으로 만든 후 용접에 의하여 제작하였다. 또한, 보강대도 강판을 굽힘 가공하여 제작하였다. 높이 조절용 홈은 CNC 밀링머신에 의하여 가공하였다. 4차례의 시제품을 제작하여 내하중 실험을 수행하였으며, 시험의 결과를 반영하여 새로이 제작하였다. 내하중 시험에서 용접부의 파손은 발생하지 않았으며, 주로 변형은 높이조절 홈과 가셋트 판이 접촉하는 부위에서 발생하였다. 450kN의 부하 하중에 의해 1~2.7mm의 변형이 발생하지만, 하중을 제거한 후에 거의 잔류변형이 없으며, 맨홀뚜껑의 분해 및 재조립이 가능하기 때문에 내하중 평가도 만족하는 것으로 판정받았다.

• 한국기계가공학회지
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• 제14권6호
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• pp.27-34
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• 2015

Dynamic vibration absorbers are widely used in machinery, buildings, and structures, including bridges. Two cases of their usage are considered in this paper. One is a simply supported beam subjected to either a moving force or a sequence of moving forces, which simulates a train-bridge interaction problem. The other is a case where a primary system is mounted on a base that is not grounded and is excited by an external force. The conditions that the dynamic vibration absorbers must meet in these cases are found and compared to those for usual cases where bases of primary systems are grounded.

• 한국기계가공학회지
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• 제12권4호
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• pp.3-9
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• 2013

Falling related injuries are categorized as the most serious and common medical problems experienced by the elderly. Hip joint fracture, one of the most serious consequences of falling in the elderly, occurs in only about 1% of falling. In this study, according to the loading conditions, the analysis is the behavior of the femur. The CT images using the commercial program "Mimics" the bones of three-dimensional CAD data generated, and we will analyze the results of finite element analysis. The boundary conditions on the basis of existing research has been simplified. In this paper, the whole femur was assumed to be isotropic linear elastic material. Predicted the behavior of the femur according to the loading condition, it can be help the development of high-precision artificial bones and joints can be treated with surgery and will be able to perform efficiently.

• 한국기계가공학회지
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• 제14권3호
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• pp.92-98
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• 2015

This study investigates the durability of a two-passenger bicycle frame under non-uniform fatigue load. The bicycle frame of Model 1 installed with reinforcement support has a 20% lower maximum equivalent stress than the existing Model 2. Model 1 has a maximum total deformation that is less than half that of Model 2. Model 1 has a higher maximum fatigue life than Model 2. In addition, Model 1 has lower fatigue damage than Model 2. Thus, the bicycle frame of Model 1 installed with reinforcement support can be described as safer, as it offers more strength than Model 2. Applying this result to the design of a real two-passenger bicycle frame under non-uniform fatigue load can effectively prevent fatigue damage and improve durability.

• 한국기계가공학회지
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• 제11권5호
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• pp.13-20
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• 2012

In order to clarify the effect of overload on crack growth behaviors, fatigue tests for overload were carried out for round plain specimens of SM45C steel. In the experiment, typical semi-elliptical crack shape was found and further crack growth behaviors were tested. Using three types of single overload fatigue tests, Crack growth retardation phenomenon were examined. The growth rate of surface crack(da/dN) during retardation period was analyzed in terms of ${\Delta}K$ and ${\Delta}K_{eff}$. On the growth rate of surface crack analyzed by ${\Delta}K$, the dependence of overload stress levels appears. However, on the growth rate by ${\Delta}K_{eff}$ obtained by Willenborg analysis, there is a non-liner relationship between da/dN and ${\Delta}K_{eff}$ with narrow scatter band.

• 한국기계가공학회지
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• 제15권6호
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• pp.64-69
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• 2016

Vehicle clutch measurement for disc cushion variation was developed for the production of high quality Dual clutch transmissions. The developed device is composed of load cells for load measurement and LVDT for measuring the distance variation measurement in cushion variation. The servo motor-driven electric press for flexible loads that was developed was controlled by a PC-based HMI system, LabVIEW, and the device was able to continuously record real time measurement data with the accuracies of ${\pm}0.1\;kgf$ load and ${\pm}5{\mu}m$ cushion amount, which is far above the requirements of commercial vehicle standards.

• 한국기계가공학회지
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• 제7권2호
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• pp.16-22
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• 2008

This study was analyzed dynamically by finite element method about the results of experiments which materials were applied by dynamic load. And they were compared with each other as the simulation data applied onto dynamic impact velocities of 6.4, 16.7 and 18.47m/s. The crack energy release rate, von-Mises stress and the displacement according to the load applied by block were calculated numerically by computer. As the numerical simulation data of specimen analyzed in this study approached the experimental data, the inspection of this specimen model suggested in this paper could be reasonable for the numerical simulation.

• 한국기계가공학회지
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• 제11권4호
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• pp.82-89
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• 2012

In order to clarify the effect of overload on crack growth behaviors, fatigue tests for overload were carried out for round plain specimens of SM45C steel. In the experiment, typical semi-elliptical crack shape was found and further crack growth behaviors were tested. Using three types of single overload fatigue tests, Crack growth retardation phenomenon were examined. The growth rate of surface crack(da/dN) during retardation period was analyzed in terms of ${\Delta}K$ and ${\Delta}K_{eff}$. On the growth rate of surface crack analyzed by ${\Delta}K$, the dependence of overload stress levels appears. However, on the growth rate by ${\Delta}K_{eff}$ obtained by Willenborg analysis, there is a liner relationship between da/dN and ${\Delta}K_{eff}$ with narrow scatter band.

• 한국기계가공학회지
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• 제8권4호
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• pp.129-135
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• 2009

In this paper, a finite element model is presented for the prediction of roll force and strip thickness in a backup-roll-drive mill. The proposed FE model is focused mainly on analyzing the elastic/plastic behavior between a work roll and a strip as well as the rigid/plastic behavior between a backup roll and a work roll. The capability of the proposed model is demonstrated through application to 4-high silicon steel rolling mill at POSCO. Results show that the predicted roll force and strip thickness rolled accurately agree with the measured them. It is also illustrated that the proper position of work roll displaced to one side from the vertical centerline of the backup-roll may be determined by minimizing the horizontal force of work roll.

• 소성∙가공
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• 제6권6호
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• pp.482-488
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• 1997

New carbon equivalent equation for the better prediction for the better prediction of roll force in a continuous hot strip mill has been formulated by applying a neural network method. In predicting roll force of steel strip, carbon equivalent equation which normalize the effects of various alloying elements by a carbon equivalent content is very critical for the accurate prediction of roll force. To overcome the complex relationships between alloying elements and operational variables such as temperature, strain, strain rate and so forth, a neural network method which is effective for multi-variable analysis was adopted in the present work as a tool to determine a proper carbon equivalent equation. The application of newly formulated carbon equivalent equation has increased prediction accuracy of roll force significantly and the effectiveness of neural network method is well confirmed in this study.