• 대한기계학회논문집B
• /
• 제36권1호
• /
• pp.47-54
• /
• 2012

본 연구는 전통적인 픽-엔-플레이스 방법을 대체하기 위한 새로운 유체 자가-조립 방법을 개발하였다. 이 방법은 종래의 연구보다 경제적이고 효과적인 방법이다. 이를 위해, 중요한 변수인 항력, 모세관 힘, 복원력을 선정하여 이들이 칩과 기판의 부착 및 정렬에 미치는 영향을 알아보기 위해 이론값과 실험값을 비교하였다. 유체 자가-조립 실험에서는 $500{\mu}m$ 솔드 볼에서 96.5% 부착률과 미정렬 $5^{\circ}$ 인 우수한 결과를 도출하였다.

• 한국전자통신학회논문지
• /
• 제6권6호
• /
• pp.889-895
• /
• 2011

영구자석 선형 동기 전동기(Permanent Magnet Linear Synchronous Motor:이하 PMLSM)는 구조적으로 간단하며 고속화 고추력화 등의 많은 장점을 가지고 있지만 전기자 권선부의 슬롯-치 구조로 인한 코깅력과 단부효과에 의한 코깅력이 발생한다. 이는 추력 맥동의 원인이 되며, 소음과 진동을 발생시킨다. 따라서, 본 연구에서는 전기자를 분산배치 할 경우 필연적으로 생기는 단부에 의한 코깅력을 저감하기 위해 PMLSM의 가동자에 보조극의 설치를 제안하였다. 또한 2차원 유한요소법(Finite Element Analysis)을 이용하여 단부 코깅력이 최소가 되는 보조극의 형태를 설계하고 전기자의 권선 방식에 따른 단부 코깅력 특성을 비교하였다.

• 대한기계학회논문집A
• /
• 제26권8호
• /
• pp.1631-1637
• /
• 2002

This paper presents a method for calculating contact force between bodies on plane. At each integration time step, the proposed method finds expected contact point on their outlines and then calculates penetration, velocity of penetration and contact force. This paper adopts continuous analysis method and multi-point contact method to calculate contact force. To obtain the accurate expected contact point on their outlines, a new algorithm is developed. The accuracy of the proposed algorithm is demonstrated by comparing the numerical results of the proposed method and DADS.

• 전기학회논문지
• /
• 제65권10호
• /
• pp.1738-1745
• /
• 2016

In this paper, we present localization and autonomous navigation method using GPU(Graphics Processing Unit)-based SIFT(Scale-Invariant Feature Transform) algorithm and virtual force method for mobile robots. To do this, at first, we propose the localization method to recognize the landmark using the GPU-based SIFT algorithm and to update the position using extended Kalman filter. And then, we propose the A-star algorithm for path planning and the virtual force method for autonomous navigation of the mobile robot. Finally, we demonstrate the effectiveness and applicability of the proposed method through some experiments using the mobile robot with OPRoS(Open Platform for Robotic Services).

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 추계학술대회 논문집(II)
• /
• pp.538-543
• /
• 2003

This study is the developed prediction of residual effective prestress force of prestressed concrete beam bridges. Developed prediction method is based on the center camber of prestressed concrete beam, structural design. report of various PSC beams, construction reference materials of PSC beams. Evaluation of residual effective prestress force by developed method is compared with evaluation by structural design. This comparison results shows that this developed method is very effective method. Therefore prediction of residual effective prestress force by this developed method will be used for evaluation of the rating of various PSC beam bridges(road bridges and railway bridges).

• Structural Engineering and Mechanics
• /
• 제59권6호
• /
• pp.973-992
• /
• 2016

A direct and relatively simple method for controlling nodal displacements and/or internal bar forces has been developed for prestressable structural assemblies including complex elements ("macro-elements", e.g., the pantographic element), involving Matrix Condensation, in which structural matrices being built up from matrices of elementary elements. The method is aimed at static shape control of geometrically sensitive structures. The paper discusses identification of the most effective bars for actuation, without incurring violation in bar forces, and also with objective of minimal number of actuators or minimum actuation. The advantages of the method is that the changes for both force and displacement regimes are within a single formulation. The method can also be used for adjustment of bar forces to either reduce instances of high forces or increase low forces (e.g., in a cable nearing slack).

• 센서학회지
• /
• 제25권2호
• /
• pp.110-115
• /
• 2016

This paper describes the design and fabrication of a three-axis force sensor with three parallel plate structures(PPSs) for measuring force in a finger force measuring system for a spherical object catch. The three-axis force sensor is composed of a Fx force sensor, Fy force sensor and a Fz force sensor, and the elements of Fx force sensor and Fy force sensor are a parallel plate structure(PPS) respectively and Fz force sensor is two PPS. The three-axis force sensor was designed using FEM(Finite Element Method), and manufactured using strain-gages. The characteristics test of the three-axis force sensor was carried out. As a test results, the interference error of the three-axis force sensor was less than 1.32%, the repeatability error of each sensor was less than 0.04%, and the non-linearity was less than 0.04%.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.480-480
• /
• 2008

Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.982-986
• /
• 1997

A method using cutting force signal and neural network for detection tool damage is proposed. Cutting force signal is gained by tool dynamometer and the signal is prepocessed to normalize. Cutting force signal is changed by tool state. When tool damage is occurred, cutting force signal goes up in comparison with that in normal state. However,the signal goes down in case of catastrophic fracture. These features are memorized in neural network through nomalizing couse. A new nomalizing method is introduced in this paper. Fist, cutting forces are sumed up except data smaller than threshold value, which is the cutting force during non-cutting action. After then, the average value is found by dividing by the number of data. With backpropagation training process, the neural network memorizes the feature difference of cutting force signal between with and without tool damage. As a result, the cutting force can be used in monitoring the condition of cutting tool and neural network can be used to classify the cutting force signal with and without tool damage.

• 한국공작기계학회논문집
• /
• 제10권1호
• /
• pp.1-9
• /
• 2001

The development of flexible automation in the manufacturing industry is concerned with production activities performed by unmanned machining system A major topic relevant to metal-cutting operations is monitoring toll wear, which affects process efficiency and product quality, and implementing automatic toll replacements. In this paper, the measurement of the cutting force components has been found to provide a method for an in-process detection of tool wear. The static com-ponents of cutting force have been used to detect flank wear. To eliminate the influence of variations in cutting conditions, tools, and workpiece materials, the force modeling is performed for various cutting conditions. The normalized force dis-parities are defined in this paper, and the relationships between normalized disparity and flank were are established. Final-ly, artificial neural network is used to learn these relationships and detect tool wear. According to proposed method, the static force components could provide the effective means to detect flank wear for varying cutting conditions in turning operation.