• 소성∙가공
• /
• 제7권1호
• /
• pp.66-71
• /
• 1998

The present study is concerned with the hydrostatic extrusion process of copper-clad aluminium bar to investigate the bonding conditions as well as the basic flow characteristics. Considering the bonding mechanism of bi-metal contact surface as cold pressure welding the normal pressure and the contact surface expansion are selected as process parameters governing the bonding conditions, in this study the critical normal pressure required for the local extrusion-the protrusion of virgin surfaces by the surface expansion at the interface-is obtained using a slip line method and is then used as a criteron for the bonding. A rigid plastic finite element method is used to analyze the steady state extrusion process. The interface profile of bi-metal rod is predicted by tracking the paths of two particles adja-process. The interface profile of bi-metal rod is predicted by tracking the paths of two particles adja-cent to interface surface. The contact surface area ration and the normal pressure along the interface are calculated and compared to the critical normal pressure to check bonding. It is found that the model predictions are generally in good agreement with the experimental observations. The compar-isons of the extrusion pressure and interface profile by the finite element with those by experi-ments are also given.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.285-286
• /
• 2006

The essential tasks to operate the welding robot are the acquisition of the position and/or shape of the parent metal. For the seam tracking or the robot automation, many kinds of contact and non-contact sensors are used. Recently, the vision sensor is most popular. In this paper, the development of the system which measures the profile of the welding part is described. The total system will be assembled into a compact module which can be attached to the head of welding robot system. This system uses the line-type structured laser diode and the vision sensor It implemented Direct Linear Transformation (DLT) for the camera calibration as well as radial distortion correction. The three dimensional shape of the parent metal is obtained after simple linear transformation and therefore, the system operates in real time. Some experiments are carried out to evaluate the performance of the developed system.

• 한국정밀공학회지
• /
• 제23권5호
• /
• pp.51-58
• /
• 2006

The necessities for heightening fuel efficiency as well as lightweight design, lead to an increase of the use of aluminum alloys in the automobile industry. Extruded aluminum profile channels are used widely for the design of frame parts as lightweight assemblies, especially if a high stiffness is needed. While many applications can be realized with forming of hollow square-sectioned extruded profiles such as a stretch bending and a hydro-forming, some applications demand the use of a press bending which can be hardly found in the previous study. In this study, by introducing the use of a press bending into car sub-frames, the demands for higher accuracy as well as higher flexible method than the conventional methods will be satisfied. With respect to the design of sub-frames, the process planning was performed from the shape of a sub-frame product. The designed processes were analyzed by the commercial FEM code, DEFORM-3D. Forming dies for the each process were designed and prototypes of sub-frames were manufactured by the verified farming process. In addition, some of the important features of design parameters in the press bending were reviewed.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.296-296
• /
• 2012

LCD panel 검사를 위한 Probe unit은 대형 TV 및 모바일용 스마트폰을 중심으로 각광을 받고 있는 소모성 부품으로 최근 pitch의 미세패턴화가 급속히 진행되고 있다. 본 연구에서는 Slit Wafer 제작 공정을 최적화하기 위해 25 um pitch의 마스크를 설계, 제작하였다. 단공과 장공을 staggered 형태로 배열하여 25 um/25 um line/space pitch로 설계하였다. 또한 단위실험을 위해 직접 25 um pitch로 설계하여, 동일한 실험조건을 적용하여 최적 조건을 찾고자 하였다. 반응변수는 Etch rate 및 profile angle로 결정하였으며, 약 200~400 um 에칭된 slit의 상단과 하단의 폭, 그리고 식각깊이를 SEM 측정사진을 통해 정한 후 etch rate 및 profile angle을 결정하였다. 인자는 식각속도 및 wall의 각도를 결정하는 식각 및 passivation 가스의 유량, chamber 압력(etching/passivation), 식각시간 등으로 정하였으며, 이들의 최대값과 최소값 2 수준으로 실험계획을 설계하였다. 식각 조건에 따라 8회의 실험을 수행하였다. 가스의 유량은 SF6 400 sccm, C4F8 400 sccm, 식각 싸이클 시간은 5.2~10.4 sec, passivation 싸이클시간 4 sec로 하였으며, 압력은 식각시 7.5 Pa, passivation 시 10 Pa로 할 경우가 가장 sharp하게 나타났다. Coil power 와 platen power는 각각 2.6 KW, 0.14 KW로 하였으며, 최적화를 위한 인자의 값들은 이 범위에서 조절하였다. 이러한 인자의 조건 조절을 통해 etch rate는 5.6 um/min~6.4 um/min, $88.9{\sim}89.1^{\circ}$의 profile angle을 얻을 수 있었다.

• 조명전기설비학회논문지
• /
• 제25권6호
• /
• pp.100-107
• /
• 2011

Since transmission and distribution neutral wires are connected with a substation grounding grid, it is very difficult to measure grounding resistance of isolated substation grounding grid after the substation is energized. It is impractical to isolate the grounding grid from other parallel connections such as distribution line neutrals and overhead ground wires for grounding resistance measurement only. In this paper, we proposed and demonstrated a novel measurement method of grounding resistance of isolated substation grounding grid. For this method, grounding current division factor and conventional FOP(Fall-Of-Potential) profiles were measured at power supplying 154[kV] substation. The obtained FOP profile was processed with the measured grounding current division factor to produce the grounding resistance of isolated grounding grid. Simulated FOP profile agreed well with the measured one showing the validity of the proposed method.

• 한국광학회지
• /
• 제18권2호
• /
• pp.130-134
• /
• 2007

광역의 자유곡면 형상을 나노미터 정밀도로 측정하기 위한 새로운 형상 측정법으로서 곡률에 근거한 형상 측정법을 제안한다. 곡률 형상 측정기는 피측정물을 일정간격으로 스캔하는 간섭계로써 각 국부영역의 형상으로부터 곡률을 획득하여, 이로부터 전 영역의 형상을 복원한다. 제안된 곡률 형상 측정기는 비구면 형상 측정을 위해 개발된 보상 광학계(Null optics)나 국부영역의 형상을 측정하고 결합하는 subaperture-slicking 법에 비해 측정 장비로부터 발생하는 시스템 오차를 근본적으로 제거하는 특징을 가진다. $80mm\times80mm\times25mm$ 작동구간을 갖는 Stewart Platform과 상용 트와이만 그린 간섭계를 이용하여 곡률간섭계를 구성하였으며, 자유곡면의 형상측정을 위한 첫 단계로서 잘 알려진 구면형상을 측정하고, 기존 장비의 측정값과 비교한 결과 32 mm영역에서 최대 56 nm의 차를 보임을 확인하였다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
• /
• pp.1991-1996
• /
• 2011

The detail design of overhead line can be dievided into a pegging plan and MD(Mounting Diagram) process. A program can perform a MD process was already developed and used in Honam High-Speed project. In this study, a pegging plan program which can perform mast distribution automatically is developed. The system is developed based on dot net framework 4.0 and Civil3D 2012 and used spread 4.0 component for grid UI. It can not be directly used a rail horizontal alignment and long-section profile together on drawing. Therefore using Civil3D, mathematical alignment and profile of rail can be accomplished. And this program has an advantage of user friendly operation because of close relationship between the two.

• 천문학회보
• /
• 제40권1호
• /
• pp.90.2-90.2
• /
• 2015

We present the high-resolution spectrum of the S-type symbiotic star V455 Sco obtained with the Dupont telescope in 2014 June. We note that the Raman-scattered O VI ${\lambda}1032$ at $6825{\AA}$ exhibits a triple-peak profile. Adopting an accretion disk model with an additional contribution from a collimated bipolar outflow, we attempt to fit the profile. We propose that the blue and central peaks are formed via Raman-scattering of O VI line photons from the accretion flow and that the bipolar flow is responsible for the remaining red peak. It is also noted that V455 Sco exhibits the Raman-scattered He II features blueward of $H{\alpha}$ and $H{\beta}$.

• ETRI Journal
• /
• 제37권2호
• /
• pp.328-337
• /
• 2015

This paper applies acceleration/deceleration control-based velocity profiles to an infeed control algorithm for a cross-belt-type sorting system to improve the accuracy and performance of the system's infeed. The velocity profiles are of a trapezoidal shape and often have to be modified to ensure that parcels correctly synchronize with their intended carriers. Under the proposed method, an infeed line can handle up to 5,600 items/h, which indicates a 40% increase in performance in comparison with its existing handling rate of 4,000 items/h. This improvement in performance may lead to a reduction in the number of infeed lines required in a sorting system. The proposed infeed control algorithm is applied to a cross-belt-type sorting system (model name: SCS 1500) manufactured by Vanderlande Industries.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
• /
• pp.370-377
• /
• 2002

Generally, the system of calculation for the multi-path ultrasonic flow meters can be divided into two methods by how to get the mean velocity, namely, weighting and direct method. Weighting-method derive the mean velocity through modeling in theoretical velocity profile. Direct-method derive the mean velocity though actual flow distribution. The system of calculation varies with maker's transducer configuration and integration method. Each system has merits and demerits. This paper describes the system of integration that calculates line velocity over cross-section of the circular pipe. Flow rate mr discussed in this paper is a difference between theoretical flow rate and integrated flow rate according to values of Reynolds number in symmetric flow field or theoretical flow rate and integrated flow rate according to rotated model in asymmetric flow field.