• 소성∙가공
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• 제31권5호
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• pp.296-301
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• 2022

In this study, influence of the process parameters of the roller leveling process on the straightness of the steel wire was analyzed using numerical analysis. To construct the numerical analysis model, cross-sectional and longitudinal element sizes, which affect the prediction accuracy of longitudinal stress caused by bending deformation of the steel wire, were optimized, and mass scaling that satisfies prediction accuracy while reducing computational time was confirmed. By using the constructed numerical analysis model, the influence of various process parameters such as input direction of the steel wire, initial diameter of the steel wire, back tension and intermesh on the straightness was confirmed. The simulation result shows that the 3^rd and 4^th roller of vertical straightener had a significant influence on vertical shape of the steel wire.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.118-125
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• 2012

본 논문은 가설 와이어 케이블 동적모델과 장력유지/이동 제어를 위한 작업로봇의 제어기 설계에 대하여 나타내었다. 제어기 설계를 위해서 로봇이 가설 와이어 케이블의 일정장력을 유지하고 당기면서 이동할 때 와이어의 길이 변화와 무게 변하의 영향을 고려한 와이어 동적모델을 나타내었다. 또한 와이어 동적모델에 기초하여 로봇 이동 시작에서 발생하는 장력이 수치해석에 의해 검토되었다. 가설 와이어 동적 모델에 기초하여 장력/이동제어를 위한 작업로봇이 구성되었고 두 동작이 서로 간섭이 억제되는 피드포워드 제어기가 설계되었다. 작업 로봇의 운전조건에 따른 시뮬레이션과 실제 실험결과는 그 유효성이 검증되었다.

• 소성∙가공
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• 제15권6호
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• pp.421-427
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• 2006

Drawing process of Al-1%Si bonding wire considering fine Si particle is analyzed in this study using FE-simulation. Al-1%Si boding wire requires electric conductivity because Al-1%Si bonding wire is used for interconnection in semiconductor device. About 1% of Si is added to Al wire for dispersion-strengthening. Distribution and shape of fine Si particle have strongly influence on the wire drawing process. In this study, therefore, the finite-element model based on the observation of wire by continuous casting is used to analyze the effect of various parameters, such as the reduction in area, the semi-die angle, the aspect ratio, the inter-particle spacing and orientation angle of the fine Si particle on wire drawing processes. The effect of each parameter on the wire drawing process is investigated from the aspect of ductility and defects of wire. From the results of the analysis, it is possible to obtain the important basic data which can be guaranteed in the fracture prevention of Al-1 %Si wire.

• 한국항공우주학회지
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• 제30권8호
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• pp.30-36
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• 2002

풍동시험 모형은 모형 지지부 삽입 등으로 실제 비행체와 다른 형상을 갖게 된다. 이러한 형상의 차이는 비행시험과 다른 힘과 모멘트를 발생시키게 되므로 이에 대한 보정은 필수적이다. 이러한 보정에는 cavity 압력 보정, 모형 지지부 간섭 보정 등이 있다. 본 시험에 사용된 모형은 내장밸런스와 함께 벨리 스팅 지지부를 사용하였으며 보정을 위하여 모형지지부 두께변화 방법과 더미 스팅 방법, wire support 방법의 시험결과를 비교하였다. 모형 지지부 두께 변화 방법은 간섭이 거의 없는 것으로 알려진 wire support 방법과 시험결과가 잘 일치하였다.

• International Journal of Aeronautical and Space Sciences
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• 제18권2호
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• pp.378-387
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• 2017

The combined model following control (MFC)-decoupler system is employed for a full authority fly-by-wire utility helicopter to enhance handling qualities. The MFC, which governs the vehicle to follow the prescribed model, is widely employed for modern helicopters. However, it may not be sufficient as helicopters often suffer significant cross coupling. The coupled responses between control axes of a helicopter increase the pilot's work load and may degrade handling qualities. As the decoupler is introduced to the MFC, the combined MFC-decoupler effectively solves the coupling problems and enhances handling qualities. The proposed system is verified via the handling qualities prediction using the mathematical dynamics model. The analysis results are confirmed through the piloted simulation.

• 대한기계학회논문집A
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• 제41권10호
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• pp.997-1004
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• 2017

엘리베이터 와이어로프의 수명은 제품의 매우 중요한 특성 가운데 하나로서 사용자의 안전 및 장비의 정비 정책과 밀접한 관계가 있다. 엘리베이터 와이어로프의 수명을 사용조건에서 측정하는 것은 매우 비경제적이다. 이 연구에서는 엘리베이터 와이어로프 (8x19W-IWRC)의 가속열화시험 데이터를 활용하여 와이어로프의 수명을 추정하는 방법을 다루었다. 굽힘피로시험기를 이용하여 가속열화시험을 진행하였으며 가속변수로는 인장하중을 사용하였다. 와이어로프의 수명은 대수정규분포를 가정하였고, 선형회귀모형을 이용하여 가수명을 구한 후 가속수명모형을 이용하여 와이어로프의 수명을 추정하는 방법과 고장 확률에 대한 로지스틱 회귀모형을 이용하여 추정하는 방법을 제시하고 두 모형의 수명 추정결과를 비교하였다.

• 대한치과기공학회지
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• 제20권1호
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• pp.91-98
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• 1998

Bonded lingual retained are divided into two common types; preformed retainers with attached mash pads, and those that are custom fabricated from standard round ir multi-standed wire. The clinician may encounter problems in the bonding process of both types of retainers because of an inability to accurtely place and temporarily stability the wire in the same position as it was adapted an a guide model. Because of these problems, a new fabrication technique of bonded lingual retainers which increase their accuracy and ease of placement and also increased their tretention was suggested by the author. Using a current model as a guide, this bonded lingual retainer was fabricated from $.028"{\sim}.032"$ standard round wire. The wire was formed with pliers for idel adapation to the lingual surfaces of the involved teeth. Right angle bends were placed in the retainer wire ends and custom "composite" bonding pads were added to the ends of the retainer wire. This bonded lingual retainer with custom "composite" bonding pads is easir to place because of the increased stability and the accuracy of placement is greatly increased. The increased insure that the retainer comforms ideally to the lingual surface of the teeth being retained.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.241-262
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• 2006

NiTi-wire shape memory alloy (SMA) dampers, that utilize NiTi SMA wires to simultaneously damp tension, compression and torsion, was developed for structural control implementation in this study. First, eight reduced-scale NiTi-wire SMA dampers were constructed. Then tension, compression and torsion experiments using the eight reduced-scale NiTi-wire SMA dampers of different specification were done. The experimental results revealed all of the eight reduced-scale NiTi-wire SMA dampers had the ability to simultaneously supply tension-compression damping and torsion damping. Finally, mechanics analysis of the NiTi-wire SMA dampers was done based on a model of the SMA-wire restoring force and on tension-compression and torsion damping analysis. The damping analytical results were found to be similar to the damping experimental results.

• 한국기계가공학회지
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• 제18권9호
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• pp.100-105
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• 2019

In wire drawing, aterial deformation is concentrated on the surface of the drawn wire because of surface contact with the drawing die. Therefore, strain varies from the center to the surface of the drawn wire. In this study, based on the upper bound method, an effective strain prediction method from the center to the surface of a drawn wire was proposed. Using the proposed method, the effective strain of the drawn wire was calculated verify the proposed prediction method, the predicted effective strain was compared with the result of finite element analysis.

• 한국소음진동공학회논문집
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• 제12권9호
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• pp.731-737
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• 2002

Nonlinear vibration of the CRT shadow mask with impact damping wires is analyzed in consideration of the mask tension distribution and the effect of wire impact damping. A reduced order FEM model of the shadow mask is obtained from dynamic condensation of the mass and stiffness matrices, and damping wire is modeled using the lumped parameter method to effectively describe its contact interactions with the shadow mask. The nonlinear contact-impact model is composed of spring and damper elements, of which parameters are determined from the Hertzian contact theory and the restitution coefficient, respectively. The analysis model of the shadow mask with damping wires is experimentally verified through impact tests of shadow masks performed in a vacuum chamber.