• 한국생산제조학회지
• /
• 제18권3호
• /
• pp.315-320
• /
• 2009

The purpose of this study is to predict the roundness of Numerical Control Machining so that helps the operator to choose the right machining conditions to produce a product within the given error limits. Learning of neural network is Backpropagation theory. From this study, the base was set to setup the database to produce precisely machined product by predicting the rate of error in the fabrication facility which does not have the environment to analyze it.

• 한국기계가공학회지
• /
• 제20권12호
• /
• pp.136-144
• /
• 2021

The purpose of this study was to develop and verify a precision transmission error measurement system for a gear pair. The transmission error measurement system of the gear pair was developed as a measurement unit, signal processing unit, and signal analysis unit. The angular displacement for calculating the transmission error of the gear pair was measured using an encoder. The signal amplification, interpolation, and transmission error calculation of the measured angular displacement were conducted using a field-programmable gate array (FPGA) and a real-time processor. A high-pass filter (HPF) was applied to the calculated transmission error from the real-time processor. The transmission error measurement test was conducted using a gearbox, including the master gear pair. The same test was repeated three times in the clockwise and counterclockwise directions, respectively, according to the load conditions (0 - 200 N·m). The results of the gear transmission error tests showed similar tendencies, thereby confirming the stability of the system. The measured transmission error was verified by comparing it with the transmission error analyzed using commercial software. The verification showed a slight difference in the transmission error between the methods. In a future study, the measurement and analysis method of the developed precision transmission error measurement system in this study may possibly be used for gear design.

• 한국생산제조학회지
• /
• 제8권4호
• /
• pp.19-28
• /
• 1999

In order to control thermal deformation of the machine origin of machine tools a empirical model and a compensation system have been developed, Prior to empirical modeling the volumetric error considering shape errors and joint errors of slides is formulated through the homogeneous transformation matrix (HTM) and kinematic chain. Simulation results of the HTM method show that the thermal error of the machine origin is more critical than position-dependent errors. In order to make a stable and effective software error compensation system the GMDH (Group Method of Data Handling) models are constructed to estimate the thermal deformation of the machine origin by measuring deformation data and temperature data. A test bar and gap sensors are used to measure the deformation data. In order to compensate the estimated error the work origin shift method is developed by implementing a digital I/O interface board between a CNC controller and an IBM PC. The method shifts the work origin as much as the amounts which are calculated by the pre-established thermal error model. The experiment results for a vertical machining center show that the thermal deformation of the machine origin is reduced within $\pm$5$mu extrm{m}$.

• 한국생산제조학회지
• /
• 제22권4호
• /
• pp.735-739
• /
• 2013

The error motion of a machine tool spindle directly affects the surface errors of machined parts. Spindle motion errors such as three translational motions and two rotational motions are undesirable. These are usually due to the imperfectness of bearings, stiffness of spindle, assembly errors, and external force or unbalance of rotors. The error motions of the spindle need to be reduced for achieving the desired performance. Therefore, the level of error motion needs to be estimated during the design and assembly process of the spindle. In this study, an estimation method for five degree-of-freedom (5 DOF) error motions for a spindle with an angular contact ball bearing is suggested. To estimate the error motions of the spindle, the waviness of the inner-race of bearings and an external force model were used as input data. The estimation model considers the geometric relationship and force equilibrium of the five DOFs. To calculate the error motions of the spindle, not only the imperfections of the shaft and bearings but also driving elements such as belt pulley and direct driving motor systems are considered.

• 한국정밀공학회지
• /
• 제26권6호
• /
• pp.50-58
• /
• 2009

Micro laser fabrication techniques can potentially be used for the manufacture of microstructures on the thin flat surfaces with large diameter that are frequently used in semiconductor industries. However, the large size of wafers can cause the degraded machining accuracy of the surface because it can be tilted or distorted by geometric errors of machines or the holding fixtures, etc. To overcome these errors the off-line focusing error compensation method is proposed. By using confocal autofocus system, the focusing error profile of machined surface is measured along the pre-determined path and can be compensated at the next machining process by making the corrected motion trajectories. The experimental results for silicon wafers and invar flat surfaces show that the proposed method can compensate the focusing error within the level of below $6.9{\mu}m$ that is the depth of focus required for the laser micromachining process.

• 산업공학
• /
• 제14권2호
• /
• pp.120-126
• /
• 2001

Virtual manufacturing is a technology facilitating effective development and agile manufacturing of products via sophisticated computer models representing physical and logical schema and behavior of real manufacturing systems including manufacturing resources, environments, and products. Based on these models, virtual manufacturing supports decision making and error checking in the entire manufacturing processes from design to mass production. At first, we analyzed manufacturing preparation activities of the four major production shops such as press, body assembly, painting and final assembly, of a Korean automotive company. We then developed the workflow models out of the analysis by the IDEF methodology, and generated a strategic plan for the systematic application of the virtual manufacturing technologies. We identified many manufacturing preparation activities that can be improved by the application of virtual manufacturing technologies. Finally, we estimated the effect of improvement including time savings in car development processes and corresponding cost savings.

• 한국공작기계학회논문집
• /
• 제11권5호
• /
• pp.100-105
• /
• 2002

The comprehensive system analysis for contour milling operation and its error has performed in this study. The obtained experimental results were from the practical points of view. In down-milling operation the contour error curve illustrates bigger thean actual workpiece radius. The contour error increased when the cutter loads increased. Through the procedural evaluation, it could ascertain the characteristics of generation mechanics in circular contour machining error, and the weight of each factors.

• 한국산업정보학회논문지
• /
• 제18권4호
• /
• pp.61-72
• /
• 2013

수출증가가 경제성장을 초래한다는 수출주도성장가설에 관한 실증분석은 주로 개발도상국을 대상으로 하여 시계열 또는 횡단면 자료를 이용하여 지난 1970년대 초부터 최근까지 주요한 관심사가 되어 왔다. 이와 같은 수출주도성장가설에 관한 실증분석은 한국을 포함하여 주로 개발도상국가에 해당되는 아시아 국가들을 분석 대상으로 이루어져 왔다. 본 논문은 여러 국가들의 횡단면 분석보다는 한국의 제조산업에 초점을 맞추어 공적분검정과 오차수정모형을 추정하여 산업의 수출증가와 산업의 성장과의 관계를 조명함으로서 수출주도성장 가설을 검정하였다. 생산과 수출에서 비중이 큰 석유화학, 1차 금속 그리고 조립금속 운송기계를 포함하여 8개의 제조산업 중 6개의 제조산업이 양방향의 인과관계성을 보이고 있기 때문에 한국 제조산업에서는 전반적으로 실질수출액과 실질생산액에 사이에서 양방향의 인과성 관계가 존재한다고 결론을 내릴 수 있다.

• 산업공학
• /
• 제20권3호
• /
• pp.288-297
• /
• 2007

Success of semiconductor/LCD industry depends on its yield and quality of product. For the purpose, FDC (Fault Detection and Classification) system is used to diagnose fault state in main manufacturing processes by monitoring time series data collected by equipment sensors which represent various conditions of the equipment. The data set is segmented at the start and end of each product lot processing by a trigger event module. However, in practice, segmented sensor data usually have the features of data asynchronization such as different start points, end points, and data lengths. Due to the asynchronization problem, false alarm (type I error) and missed alarm (type II error) occur frequently. In this paper, we propose a robust process fault detection system by integrating a process event detection method and a similarity measuring method based on dynamic time warping algorithm. An experiment shows that the proposed system is able to recognize abnormal condition correctly under the asynchronous data situation.

• 한국전자거래학회지
• /
• 제23권2호
• /
• pp.97-110
• /
• 2018

4차 산업혁명 시대를 맞아, 제조 기업들은 생산성 향상을 위해 축적된 설비 데이터를 활용하여 스마트제조를 실현하는 것에 높은 관심을 두고 있다. 하지만 기존의 설비 데이터 분석 연구들은 주로 센서 데이터 등 정형 데이터를 대상으로 하여, 실제 큰 비중을 차지하고 있는 텍스트와 같은 비정형 데이터에 대한 분석 연구는 부족한 실정이다. 특히, 작업자가 수기로 작성한 텍스트 데이터를 활용한 사례는 매우 적었다. 따라서 본 논문에서는 작업자가 수기로 작성한 설비 오류 데이터를 분석하여 연관 규칙 마이닝을 통해 설비 오류 발생 패턴을 도출하는 프레임워크를 제안하고자 한다. 이때, 일반적인 텍스트 분석 기법과 같이 단어를 분석 기준으로 사용하는 경우 전문 용어에 해당하는 설비 오류의 의미를 표현하는 데에 한계가 있다는 점에 착안하여 구절을 추출하여 텍스트 분석 기준으로 사용하였다. 제안하는 프레임워크의 성능을 실제 사례를 통해 검증하였으며, 본 연구 결과를 활용하면 설비 오류를 예방하여 가동률을 높이고 나아가 제조 기업의 생산성 향상에 기여할 수 있을 것으로 기대한다.