• 소성∙가공
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• 제18권7호
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• pp.531-537
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• 2009

The effect of blank holding force on thickness variation in simultaneous sheet forming with rectangular shape and circular has been demonstrated. Because has investigated an effect on formability of magnesium sheet, in this paper, the effect of punch radius on formability have been thinning, various crack phenomena and forming velocity. By simultaneously forming process with circular and rectangular shape, the data of simultaneously forming process with circular and rectangular shape will used to a part development such as notebook computer case, cell phone and bipolar plate of fuel cell.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 추계학술대회 논문집
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• pp.120-123
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• 2000

It is well known, for many years, that deep drawability can be improved by applying variable blank holding force. To apply variable blank holding force during cup during, we set up pressure controlling system on experimental hydraulic press, and the pressure control system is often called NC(Numerically Controlled) cushion system Using the NC cushion system we compared the drawability of square steel cups with NC cushion and that with conventional cushion. The results show drawability is greatly improved when the pressure control curve is designed in a S-shaped curve. This paper includes design details of the NC cushion system and experimental analysis of drawability with experimental NC cushion system.

• 소성∙가공
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• 제10권2호
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• pp.115-122
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• 2001

It is well known, for many years, that deep drawability can be improved by applying variable blank holding force. To apply variable blank holding force during cup drawing, we set up cushion pressure control system on the hydraulic press, and the pressure control system is often called NC(Numerically Controlled) cushion system. A cushion pressure control experiment was carried out using the NC cushion and it was shown that the proposed system produced good performance. The comparison of drawability of square cups with and without NC cushion showed that the drawability could be greatly improved when S-shaped pressure curve was applied. This paper includes design details of the NC cushion system and experimental analysis of drawability with NC cushion system.

• 대한의용생체공학회:의공학회지
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• 제23권1호
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• pp.17-26
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• 2002

본 연구의 목적은 척추 내고정 시스템인 척추경 나사못의 기계적 특성 평가를 통하여 내고정 시스템에 영향을 미치는 주요 하중요소를 규명하고. 하중요소에 대한 정하중 평가와 단분절 시스템(one bevel system)에서의 피로수명을 증가시키는 방법을 제안하는 것이다. 정하중 시험에서 단일 척추경 나사못(single pedicle strew)에 작용하는 하중요소는 마찰력((friction force), 굽힘력(bending force), 결합력(holding force)으로 나타났으며, 단일 나사못의 굽힘력 시험결과로부터 단분절 시스템에 대한 시험결과의 유추가 가능하였다 척추 내고정 시스템의 상부 부분 시험의 피로수명 보다는 봉(rod)의 유연성을 포함하는 단분절 시스템에서의 피로수명이 길게 나타났고. 인체에 삽입되는 척추경 나사못 단분절 시스템에서 근육 및 ligament 등에 의해서 봉의 유연성 저하를 가져올 수 있음을 고려할 때. 단일 나사못 피로시험만으로 단분절 시스템의 피로수명 예측이 가능함을 보였다.

• 소성∙가공
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• 제8권5호
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• pp.449-453
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• 1999

Sheet metal forming process is a non-linearity problem which is affected by various process variables, such as geometric shape of punch and die, frictional characteristic, etc.. Therefore, the knowledge of the influence of the process variables is needed in the design of sheet metal working processes. In this paper, cylindrical cup drawing tests for blank holding force, punch speed and lubrication between sheet material and tool were carried out to investigate the influence upon sheet formability. Experimental results were discussed about the defects on the deformation behaviors during the forming process.

• 항공우주시스템공학회지
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• 제15권4호
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• pp.1-6
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• 2021

The non-explosive holding and release mechanism is used to prevent damage to the mission component caused by explosives when the deployment structure for Cube Satellites is separated. However, among the several types available, the non-explosive holding and release mechanism system using nylon wires depend on the nylon wire knot method and tightening power of the worker. Therefore, in this study, we conducted experiments with the operation of a new holding and release mechanism system by conceptualizing the Boa System Dial, which can provide a constant tightening force regardless of worker proficiency and deploying a imitational solar panel. In this study, the process of binding and unbinding with constant tension was recorded while applying the novel non-explosive holding and release mechanism using the Boa System Dial proposed. In addition, required advances are indicated for the application of the proposed system to actual Cube Satellites.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1994년도 추계학술대회 논문집
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• pp.80-94
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• 1994

As for axisymmetirc sheet metal forming, a kind of pick-up apparatus for body-wrinkling is deviced. Experiments with both hemispherical and flat headed punches, with various clearances between punch and die, with respect to three kinds of materials each of which has two thicknesses, are performed. Firstly the process of evolution of body-wrinkling is observed. Then the critical blank-holding force (or meridional tensile force) for suppression of body-wrinkling at a specified punch-stroke is measured for all cases mentioned above. An empirical formula for it is proposed. Deformation patterns and stress distributions are analysed by the use of FEM. A simplified critical condition for body-wrinkling is formulated and introduced into the FEM program. And its effectiveness is checked by comparison with the experimental results. Using this FEM system, the governing factors of body-wrinkling are cleared up.

• 접착 및 계면
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• 제15권2호
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• pp.49-56
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• 2014

본 연구에서는 아연 코팅 스틸코드와 접착증진제가 적용된 배합고무와의 접착 특성을 연구하였다. 접착증진제로는 cobalt boroacylate (코발트 염), resorcinol-formaldehyde resin (RF resin) 그리고 hexamethoxymethylmelamine (HMMM)을 사용하였다. 코발트 염이 첨가된 배합고무에서는 코발트 염이 아연 코팅 스틸코드 표면에서 아연 황화물 성장을 촉진시켜 코발트 염이 포함되지 않은 배합고에 비하여 pullout force가 증가하는 것을 확인하였다. 또한 코발트 염, RF resin과 HMMM을 모두 적용한 배합고무의 경우, 코발트 염은 아연 황화물 성장을 촉진시키고, RF resin과 HMMM은 배합고무의 modulus를 높여 고무 matrix로 성장한 아연 황화물을 더 강하게 interlocking하기 때문에 pullout force와 스틸코드의 고무 부착율이 가장 높게 나타난다는 것을 확인하였다.

• International Journal of Precision Engineering and Manufacturing
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• 제7권3호
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• pp.47-50
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• 2006

High-speed machining is a very useful tool and one of the most effective rapid manufacturing processes. This study sought to produce various high-speed machining materials with excellent quality and dimensional accuracy. However, high-speed machining is not suitable for microscale thin-walled structures because the structure stiffness lacks the ability to resist the cutting force. This paper proposes a new method that is able to rapidly produce very thin-walled structures. This method consists of high-speed machining followed by filling. A strong work-holding force results from the solidification of the filling materials. Low-melting point metal alloys are used to minimize the thermal effects during phase changes and to hold the arbitrarily shaped thin-walled structures quickly during the high-speed machining. We demonstrate some applications, such as thin-walled cylinders and hemispherical shells, to verify the usefulness of this method and compare the analyzed dimensional accuracy of typical parts of the structures.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.60-63
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• 2007

The effect of process parameters on springback of AZ31B magnesium alloy sheet was investigated by performing 2D draw bending test at the elevated temperatures. And also the springback characteristics were studied different blank holding forces between 30 to 250 kgf. Springback was considerably reduced at higher temperatures than $200^{\circ}C$. The blank holding force in the range used, however, had little influence on springback in isothermal tests. For a given temperature, springback decreased with increasing blank holding force in non-isothermal tests.