• 마이크로전자및패키징학회지
• /
• 제28권4호
• /
• pp.79-83
• /
• 2021

본 연구에서는 기존의 silicon alkoxide(tetraethyl orthosilicate, TEOS)에 비해 단가가 저렴하여 상업화에 유리한 물유리를 전구체로 사용하여 계면활성제의 농도에 따라 형성되는 다양한 크기의 실리카 중공 미세구(hollow silica microsphere, HSM)를 합성하였다. 계면활성제의 농도에 따른 실리카 중공 미세구의 형성에 대한 물성을 퓨리에 분광기(Fourier transform infrared spectrometer), 접촉각 측정기(contact angle measurement), Brunauer-Emmett-Teller 및 Barrett-Joyner-Halenda 분석기와 전계방사형 주사전자현미경(field emission scanning electron microscopy)를 이용하여 분석하였다. 계면활성제를 적정량의 농도로 투입하여 porou s한 물유리 기반 실리카 중공 미세구를 제조할 경우 비표면적은 169 m²/g, 평균 입자 크기 25.3 ㎛ 및 표준편차는 6.25로 우수한 실리카 중공 미세구가 형성됨을 확인하였다.

• Journal of Construction Engineering and Project Management
• /
• 제4권1호
• /
• pp.37-44
• /
• 2014

Comparatively, the construction industry has, on average, a higher rate of fatal and major injuries, work induced ill-health and damage to properties than other industrial sectors; and this is a source of concern to industry stakeholders. The study showed that although subcontracting could be contributory to an increase in workplace accidents in the construction industry, contractual aspects of subcontracting arrangements (such as the power imbalance that exist along the client-customer interface) also present opportunities for improvements in health and safety management (HSM) practices in organisations. This conclusion was reached after an analysis of a questionnaire survey (with a 27% response rate) that assessed the attitudes and perception to health and safety issues.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2017년도 춘계학술발표대회
• /
• pp.567-570
• /
• 2017

산업공정에서 공정 정보처리의 극대화를 위하여 PLC, 로봇 등의 여러 프로그램식 단위제어기기가 네트워크로 연결되어 운영되고 있다. 대부분이 RS232C와 고유 장비의 전송절차에 의해 수행되어 왔지만, ISO 등에서는 반도체공정에 적용을 위한 SECS에 대한 프로토콜을 표준화하였다. 본 연구는 반도체 스퍼터 공정에 PLC, 로봇, 반송장치의 연결에 SECS-II를 적용하고, HSMS를 활용하여 TCP/IP와 Host를 연결하여 계층구조의 네트워크를 운영하였다. 전송 메세지 type을 stream과 function으로 나누어 송수신 확인과 데이터 전송절차를 설정하여 공정이 정상적으로 운영됨을 확인하였다.

• 한국정밀공학회지
• /
• 제23권12호
• /
• pp.38-45
• /
• 2006

In this work, optimal finish machining condition considering total time for mold or electrode manufacturing was investigated. First, manual finishing time according to the machining condition was analyzed for the work material. The effect of runout and phase shift of tool path on surface finish was also considered in those analyses. Secondly, optimal manual finishing processes were determined for various machining conditions. Finally, finish machining time and corresponding manual finishing time were taken into account for the estimation of the total time of manufacturing mold. Though small feed per tooth and pick feed reduced the manual finishing time, the finish machining time increased in such conditions. With a machining condition of feed per tooth of 0.2 mm and pick feed of 0.3 mm, the minimum total time of manufacturing mold was achieved in our machining condition.

• International Journal of Precision Engineering and Manufacturing
• /
• 제3권4호
• /
• pp.31-36
• /
• 2002

A continuous tool-path, that is to cut continuously with the minimum number of cutter retractions during the cutting operations, is developed in order to minimise the fluctuation of cutting load and the possibility of chipping on the cutting edge in HSM (high-speed machining). This algorithm begins with the offset procedure along the boundary curve of the sculptured surface being machined. In the of offset procedure, the offset distance is determined such that the scallop height maintains a constant roughness to ensure higher levels of efficiency and quality in high-speed machining. Then, the continuous path is generated as a kind of the diagonal curve between the offset curves. This path strategy is able to connect to neighbor paths without cutter retractions. Therefore, the minimum tool retraction tool-path can be generated And, it allows the sculptured surface incorporating both steep and flat areas to be high-speed machined.

• 한국기계가공학회지
• /
• 제2권3호
• /
• pp.5-12
• /
• 2003

In order to reduce the lead-time and cost, many useful methods have been applied to rapid prototyping (RP) in recent years. But cutting process is still considered as one of the effective RP methods that have been developed and currently available in the industry. It also offers practical advantages in aspects of precision and versatility. However, traditional 3-axis NC machining has some inherent limitations such as the restriction of tool accessibility and the complex setup. In this work, a new rapid prototyping system with high speed 5-axis machining of plastics has been developed to overcome those limitations. And cutting experiments were conducted to determine the design factors of the system and the cutting conditions of plastics. The architecture of developed system is described in detail and the successful application examples are presented.

• Journal of Mechanical Science and Technology
• /
• 제16권1호
• /
• pp.13-23
• /
• 2002

This paper presents inverse kinematic and dynamic analyses of HexaSlide type six degree-of-freedom parallel manipulators. The HexaSlide type parallel manipulators (HSM) can be characterized as an architecture with constant link lengths that are attached to moving sliders on the ground and to a mobile platform. In the inverse kinematic analyses, the slider and link motion (position, velocity, and acceleration) is computed given the desired mobile platform motion. Based on the inverse kinematic analysis, in order to compute the required actuator forces given the desired platform motion, inverse dynamic equations of motion of a parallel manipulator is derived by the Newton-Euler approach. In this derivation, the joint friction as well as all link inertia are included. Relative importance of the link inertia and joint frictions on the computed torque is investigated by computer simulations. It is expected that the inverse kinematic and dynamic equations can be used in the computed torque control and model-based adaptive control strategies.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.965-969
• /
• 1997

Due to the high feed rate,high speed machining (HSM) provide a great potential of rationalization for the machining Dies and Moulds. But determination of cutting condition is very difficult, because cutting mechanism of high speed machining is very complicated,especially using ball end-mill. This paoer gives a report on selection of the optimal cutting condition to improve the machining efficiency, And optimal machining condition is determined through the cutting force, FFT analysis of cutting force and surface roughness according to the cutting condition. Based on this experiment result,wear process and machining characteristics are evaluated.

• 한국기계가공학회지
• /
• 제3권3호
• /
• pp.32-38
• /
• 2004

Recently, the system of high speed milling(HSM) is widely used for reducing the operation time and maximizing efficiency of work. The most research of high speed milling system is still leaves much to be desired. Specially the research of mass pocket high speed processing with high precision is the first and probably the last. So this paper showed mass pocket processing of high precision with a duralumin and then confirmed a cause of inferior goods through the CAD/CAM pattern simulation and experimentation. And this paper showed high speed processing system reduce the rate of inferior from this optimal pattern.

• 한국정밀공학회지
• /
• 제18권10호
• /
• pp.208-213
• /
• 2001

High speed milling(HSM) is one of the emerging cutting process having tremendous potential not only in increased metal removal rates but also in improved surface finish, burr free edge, dimensional accuracy and a virtually stress free component after machining. The High efficiency and accuracy in machining of die/mold materials can be obtained in high speed machining, so it is necessary to analytic the mechanism of high speed cutting process : cutting force, acoustic emission signal.