• 연구논문집
• /
• s.29
• /
• pp.173-183
• /
• 1999

The vacuum investment casting process for a large gas turbine component, Inner Preswirl Support (IPS), was simulated by using commercial FEM package ProCAST(TM) with view factor radiation method. The solid fraction in mushy zone was directly measured by Differential thermal analysis(DTA-DSC mode). Three types gating design. considering liquid flow and heat release through it. were proposed. Solidification had begun at the ribs or thin sections of the IPS casting and advanced further through the upper and lower gates. The computed temperature gradient G and G/R values at 70% solidified temperature were used for prediction of microshrinkage formation during casting. The effect of mold preheat on the thermal history of the casting displayed minute effect on the microshrinkage formation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.59-62
• /
• 2001

Reliability engineering is regarded as the major and important roll for all industry. And advanced manufacturing systems with high speed and intelligent have been developing for the betterment of machining ability. In this study, we have systemized evaluation of reliability for machinery system. We proposed the reliability assessment and design review method using analyzing critical units of high speed and intelligent machine system. In addition, we have not only designed and developed test bed system for acquiring reliability data, but also apply QFD technique for satisfying quality function which is provided in design phase. From this study, we will expect to guide and introduce the reliability engineering in developing and processing phase of high quality product.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.88-91
• /
• 2001

The reliability data analysis for components of CNC machining center is studied in this paper. The failure data of mechanical part is analyzed by Exponetial, Weibull, and Log-normal distributions. And then, the optimum failure distribution model is selected by goodness of fit test. The reliability data analysis program is developed using ASP language. The failure rate, MTBF, life, and failure mode of mechanical parts are estimated and searched by this program. The failure data and analysis results are stored in the database.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.04a
• /
• pp.432-437
• /
• 1997

In this paper, Fuzzy ART which is one of the competitive learing neural networks is applied to machine-part cell formation problem. A large matrix and varios types of machine-part incidence matrices, especially including bottle-neck machines, bottle-neck parts, parts shared by several cells, and machines shared by several cells are used to test the performannce of Fuzzy ART neural network as a cell formation algorithm. The result shows Fuzzy ART neral network can be efficiently applied to machine-part cell formation problem which are large, and/or have much imperfection as exceptions, bottle-neck machines, and bottle-neck parts.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.4
• /
• pp.51-57
• /
• 1998

It is common to assume identical allowable safety factors in static strength defined by mean stress and in fatigue, defined by stress amplitude. Under the load with asymmetrical cycles the safety factor is not the same. In this paper, with the consideration of unequal allowable safety (actors a general method for estimating fatigue reliability of a machine element under a combined state of stress is derived based on the theory proposed by Prof. Kececioglu and a normal distribution. The calculation of fatigue reliability fur limited life is discussed with example.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1997.10a
• /
• pp.875-878
• /
• 1997

Electrical discharge machining is the method of using thermal energy by electrical discharge. Generally, if the material of workpiece has conductivity even though it is very hard material and complicated shape which are difficult to cut such as quenching steel, cemented carbide, diamond and conductive ceramics, the EDM is favorable one of possible machining processes. But, the process is necessarily required of finish cut and heat treatment because of slow cutting speed, no mirror surface, brittleness and crack due to the residual stress for manufactured goods.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.899-904
• /
• 2003

Tight integration of product design and process planning in the early design stage would make bigger impact as wider spectrum of design and manufacturing alternatives can be pursued and evaluated. Thus the development of systematic computer-based support for this integration is desirable. For this integration and process planning in the early design stage. the systematic method to synthesize shape of part from functional requirements is crucial. This research presents the methods of functional decomposition from overall function or product and synthesizing shape of part based on functional relations extracted from functional decomposition using planetary gear transmission system as an example.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.11
• /
• pp.58-65
• /
• 2008

The study on dual arm robot manipulator which consists of two 6-DOF srms and one 2-DOF torso is introduced. This dual arm robot manipulator is designed for automation of assembly process in automotive manufacturing line. Each industrial 6-DOF arm can be used as a stand-alone type of industrial robot manipulator with 6-DOF and as a manipulator part of dual arm robot at the same lime. These structures help the robot maker willing to succeed in emerging market of dual arm robots have the high competitive power for the current industrial robot market and the emerging market of dual arm robot at the same time. The research results of the design concept, workspace analysis and the PC-based controller will be introduced.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1994.10a
• /
• pp.150-155
• /
• 1994

종래의 초내열합금은 원자력산업과 우주항공산업등에 주로 사용되었으며, 산업이 고도화되어짐에 따라 각종 산업기계와 자동차 분야에까지 광범위하게 사용되어지고 있다. 대표적인 초내열합금으로서의 인코넬(Inconel)은 인성과 Creep 특성이 우수하고, 특히 고온강도가 높고 화학적으로도 안정하여 부식에도 강한 장점을 지니고 있어 항공기 부품재료로서 최근 각광을 받고 있다. 본 연구에서는 일반적으로 사용되어지고 공구재종인 코팅초경합금공구와 세라믹 공구를 사용하여 초내열합금인 인코넬 600을 절삭가공하여, 절삭저항,공구의 파손 및 마모,칩의 용착현상등의 가공성에 영향을 주는 요인에 대하여 검토함으로써, 공구의 종류에 대ㄷ응하는 적절한 절삭영역을 설정하는 것을 목적으로 하였다.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.2
• /
• pp.58-65
• /
• 2003

The conventional forming process such as squeeze casting or die casting for fabricating metal matrix composites products have a disadvantage such as non homogenous distribution of reinforcement, weak bonding between matrix and reinforcement and cost increase in parts fabrication. Thixoforming process has been accepted as a new method for fabricating the net shaped metal matrix composites with lightweight and wear resistance. In this paper, the effect of volume fraction and reinforcement sizes on mechanical properties in cylinder liner part of metal matrix composites has been investigated with processes parameters such as pressure and velocity. Moreover, the methods to obtain the thixoforged composites cylinder liner with high quality has been proposed. To evaluate the composites cylinder linear fabricated at the conditions proposed in this study, mechanical properties of fabricated composites cylinder linear were compared with those of commercial composites cylinder linear.