• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.21-28
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• 2015

As film products are increasingly used in a wide range of areas, from producing traditional flexible packaging to high-tech electronic products, a higher level of quality is demanded. Most film products are made in the form of rolled finished goods, therefore, various quality issues related to their shape characteristics must be addressed. The thickness of the film products is one of the most common and important critical-to-quality attributes (CTQs). Particularly, the degree of thickness uniformity is more important than other thickness parameters, because it will be potential causes of many secondary thickness-related quality problems, such as wrinkles or faulty windings. To control the degree of thickness uniformity, the fixed bending region is oneof the most important CTQs to manage. Fixed bending regions are special points in the transverse direction of a rolled product with consistent minute variations of the thickness gap. This paper describes the measurement and analysis of thickness uniformity data, which were performed in a real manufacturing field of biaxial oriented polypropylene (BOPP) film. In previous researches, quality function deployment (QFD) or fault tree analysis were used to find the most critical process attributes out to controlthe CTQ of thickness uniformity. Whereas, this paper uses traditional control charts to find the most critical process attributes out in this problem. In addition, the selection of one of the major critical process attributes (CTPs) that is expected to affect the CTQ of thickness uniformity is also described. The selected critical-to-process attributes are the controlled temperatures along the transverse direction. A dramatic improvement in thickness uniformity was observed when the selected CTPs were controlled.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1508-1511
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• 1997

In this paper, design parameters of Rapid Thermal Processing(RrW) to minimize the wafer tempera ture uniformity errors are proposed. 1,anip ling positions and the wafer height are important parameters for waf er temperature uniformity in R'I'P. We propose the method to seek lamp ling positions and the wafer height for optimal temperature uniformity. l'he ~~roposed method is applied to seek optimal lamp ling positions and the waf er height of 8 inch wafer. 'I'o seek the optimal lamp ling positions and the wafer height, we var\ulcorner. lamp ling 110s itions and the wafer height and then formulate the wafer temperature uniformity problem to the linear programmi ng problem. Finally, it is shown that the wafer temperature uniformity in RI'I' designed by optimal prarneters is improved to comparing with Ii'l'P designed by the other method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.223-227
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• 2002

As the channel length of device shrinks below $0.13{\mu}m$, CMP(chemical mechanical polishing) process got into key process for global planarization in the chip manufacturing process. The removal rate and non-uniformity of the CMP characteristics occupy an important position to CMP process control. Especially, the post-CMP thickness variation depends on the device yield as well as the stability of subsequent process. In this paper, every wafer polished two times for the improvement of oxide CMP process characteristics. Then, we discussed the removal rate and non-uniformity characteristics of post-CMP process. As a result of CMP experiment, we have obtained within-wafer non-uniformity (WIWNU) below 4 [%], and wafer-to-wafer non-uniformity (WTWNU) within 3.5 [%]. It is very good result, because the reliable non-uniformity of CMP process is within 5 [%].

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.4
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• pp.269-275
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• 2022

In ideal configuration, elapsed-time method can measure the exact reaction wheel speed. But in real configuration, the speed measurement error exists due to tacho pulse non-uniformity. In this research, we study the method which overcome the non-uniformity effects. First, we introduce the method which spin the wheel at the specific speed and measure the non-uniformity. Then, we propose the real-time measurement error correction method which uses the obtained non-uniformity information. This method calculate the speed candidates from the elapsed-time method's counts and non-uniformity information, and choose the closest speed to the real speed. Through simulation, we show that proposed method measure the exact speed regardless of non-uniformity, and fast wheel speed control is possible.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.9
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• pp.831-835
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• 2000

The uniformity of themperature on a wafer is a wafer is one the most important parameters to conterol the RTF(Rapid Thermal Process) with proper input signals. It is impossible to achieve the uniformity of temperature without the exact estimation of temperature ar all points on the wafer. There fore, it is difficult to understand the internal dynamics as well as the structural complexities of the RTP, which is aprimary obstacle to measure the distributed temperatures on the wafer accurately. Furthermore, it is also hard to accomplish desirable estimation because only a few pyrometers are available in the general equipments. In the paper, a thermal model based on the chamber grometry of the AST SHS200 RTP system is developed to effectively control the thermal uniformity on the wafer. First of all, the estimation method of one-point measurement is developed, which is properly extended to the case of multi-point measurements. This thermal model is validated through simulation and experiments. The proposed work can be utilized to building a run-by -run or a real-time control of the RTP.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.95-105
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• 2009

A method was proposed which employed control of the drop location of fertilizer particles on a spinner disc to optimize the spread pattern uniformity. The system contained an optical sensor as a feedback mechanism, which measured discharge velocity and location, as well as particle diameters to predict a spread pattern of a single disc. Simulations showed that the feed gate adaptation algorithm produced high quality patterns for any given application rate in the dual disc spreader. The performance of the feed gate control method was assessed using data collected from a Sulky spinner disc spreader. The results showed that it was always possible to find a spread pattern with an acceptable CV lower than 15%, even though the spread pattern was obtained from a rudimentary flat disc with straight radial vanes. A mathematical optimization method was used to find the initial parameter settings for a specially designed experimental spreading arrangement, which included the feed gate control system, for a given flow rate and swath width. Several experiments were carried out to investigate the relationship between the gate opening and flow rate, disc speed and particle velocity, as well as disc speed and predicted landing location of fertilizer particles. All relationships found were highly linear ($r^2$ > 0.96), which showed that the time-of-flight sensor was well suited as a feedback sensor in the rate and uniformity controlled spreading system.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.281-288
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• 2020

In this paper, we propose a control method to solve the surface hardness non-uniformity due to flow non-uniformity occurring in the heat treatment process of marine CAM. In the water cooling method including the decarbonization method, an automation device for deformation control has been developed and applied. LSTM was used to estimate the water cooling conditions, and the proposed method was found to be meaningful by improving the prototype results.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.475-478
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• 2007

A solution for carbon nanotube based field emission displays has been designed and built. The solution makes use of structure layout to control electron beam trajectories, uniformity by use of ballasting, emission anomalies eliminated by selective carbon nanotube growth and invisible spacers to maintain the vacuum gap.

• Journal of the Korean Ceramic Society
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• v.47 no.3
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• pp.262-267
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• 2010

a-SiC has been thought as an ideal candidate for conventional silicon at many applications. However, the uniformity problem of deposition has been a obstacle for conventional use of a-SiC:H films. a-SiC:H films were deposited on (100) silicon wafer by RPECVD system in various temperature. HMDS and $H_2$ gas were used as a precursor and a carrier gas, respectively. The flow rate of HMDS source and $C_2H_2$ dilution gas was fixed in order to study the carbon effect on the film stoichiometric and bonding properties. The plasma power varied from 200 to 400W. We used three types of source delivery line to control the uniformity and film properties of deposited film. We showed that the change of source delivery line has effect on the film uniformity of deposited film and this change of line did not affect on film properties. Also, the change of deposition conditions has effect on the film uniformity.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.688-696
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• 2014

A slew-rate control method of LCD driver ICs is introduced to increase uniformity between adjacent driver ICs and reduce power consumption. The slew rate of every voltage follower is calibrated by a feedback algorithm during the non-displaying period. Under normal operation mode, the slew rate is dynamically controlled for improving power efficiency. Experimental results show that the power consumption is reduced by 16% with a white pattern and by 10% with a black pattern, and display defects are successfully eliminated.