• Journal of KIISE:Databases
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• v.31 no.2
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• pp.108-121
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• 2004

In this paper, we propose an enhanced snapshot technique that solves performance degradation when snapshot is initiated for the storage cluster system. However, traditional snapshot technique has some limits adapted to large amount storage shared by multi-hosts in the following aspects. As volume size grows, (1) it deteriorates crucially the performance of write operations due to additional disk access to verify COW is performed. (2) Also it increases excessively the blocking time of write operation performed during the snapshot creation time. (3)Finally, it deteriorates the performance of write operations due to additional disk I/O for mapping block caused by the verification of COW. In this paper, we propose an efficient snapshot technique for large amount storage shared by multi-hosts in SAN Environments. We eliminate the blocking time of write operation caused by freezing while a snapshot creation is performing. Also to improve the performance of write operation when snapshot is taken, we introduce First Allocation Bit(FAB) and Snapshot Status Bit(SSB). It improves performance of write operation by reducing an additional disk access to volume disk for getting snapshot mapping block. We design and implement an efficient snapshot technique, while the snapshot deletion time, improve performance by deallocation of COW data block using SSB of original mapping entry without snapshot mapping entry obtained mapping block read from the shared disk.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.8
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• pp.726-735
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• 2007

Inside the factory buildings of aprecision industry (which produces semiconductors or TFT-LCD), thousands of vibration-sensitive precision equipments operate in the clean rooms. Various utility equipments that are installed around them for proper operation cause various sources of noise and of vibration to exist inside the clean rooms and thus deteriorate the noise and the vibration environment within. In this study, we check if the existing transient vibration phenomenon is caused by the vibrations that arise from operating the utility installed near these equipments; compare and evaluate the vibration criteria of precision equipments regarding the transient vibration phenomenon; and check the efficiency of these criteria.

• Journal of Intelligence and Information Systems
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• v.15 no.4
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• pp.213-224
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• 2009

This paper describes a real-time scheduling system re-construction project for automated manufacturing at a 300mm wafer fab of Korean semiconductor manufacturing company. During executing this project, for each main operation such as clean, diffusion, deposition, photolithography, and metallization, each adopted scheduling algorithm was developed, and then those were implemented in a real-time scheduling system. In this paper, we focus on the scheduling algorithms and real-time scheduling system for clean and diffusion operations, that is, a serial-process block with the constraint of limited queue time and batch processors. After this project was completed, the automated manufacturing utilizations of clean and diffusion operations became around 91% and 83% respectively, which were about 50% and 10% at the beginning of this project. The automated manufacturing system reduces direct operating costs, increased throughput on the equipments, and suggests continuous and uninterrupted processings.

• IE interfaces
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• v.22 no.1
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• pp.73-84
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• 2009

In this paper, we propose a dispatching algorithm for constructing a Factory Operating System (FOS) which can operate semiconductor fabrication factories more efficiently and effectively. We first define ten dispatching criteria and propose two methods to apply the defined dispatching criteria sequentially and simultaneously (i.e. fixed dispatching architecture). However the fixed type methods cannot apply the criteria adaptively by considering changes in the semiconductor fabrication factories. To overcome this type of weakness, an adaptive dispatching architecture is proposed for applying the dispatching criteria dynamically based on the factory status. The status can be determined by combining evaluation results from the following three status criteria; target movement, workload balance, and utilization rate. Results from the shop floor in past few periods showed that the proposed methodology gives a good performance with respect to the productivity, workload balance, and machine utilization. We can expect that the proposed adaptive dispatching architecture will be used as a useful tool for operating semiconductor fabrication factories more efficiently and effectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.993-999
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• 2007

반도체나 TFT-LCD등을 생산하는 정밀산업 공장구조물에는 진동에 민감한 수많은 정밀장비(검사 및 생산용 장비)가 청정실(Clean Room)에 설치되어 운용된다. 정밀장비는 정상운용을 위하여 주변에 각종 유틸리티 설비가 설치된다. 이러한 수많은 유틸리티 설비들과 그 밖의 많은 장비들로 인하여 공장 내 청정실에는 각종 수 많은 소음/진동원들이 산재해 있다. 이러한 소음/진동원으로 인하여 청정실 내에는 소음/진동의 환경을 저하시킨다. 이에, 본 연구에서는 정밀장비 주변에 설치 된 유틸리티의 가동으로 인하여 발생하는 진동으로 인하여 간헐적으로 정밀장비에 영향을 미치는 과도진동의 현상을 확인하고, 과도진동 현상에 대하여 정밀장비에서 제시한 진동허용규제치와 비교/평가하고, 진동허용규제치의 유효성에 대하여 확인하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.1
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• pp.79-86
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• 2012

This study focuses on the problem of scheduling wafer lots of several recipe(operation condition) types in the photolithography workstation in a semiconductor wafer fabrication facility, and sequence-dependent recipe set up times may be required at the photolithography machines. In addition, a lot is able to be operated at a machine when the reticle(mask) corresponding to the recipe type is set up in the photolithography machine. We suggest various heuristic algorithms, in which developed recipe selection rules and lot selection rules are used to generate reasonable schedules to minimizing the total weighted flowtime. Results of computational tests on randomly generated test problems show that the suggested algorithms outperform a scheduling method used in a real manufacturing system in terms of the total weighted flowtime of the wafer lots with ready times.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1241-1246
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• 2005

This paper described an 8bit, 100Msample/s CMOS D/A converter using a glich-time minimization technique for the high-speed sampling rate of 100MHz level. The proposed DAC was implemented in 0,35um Hynix CMOS technology and adopts a current mode architecture to optimize sampling rate, resolution, chip area. The DAC linear characteristics was similar to the proposed specification the prototype error between DNL and INL is less than ${\pm}0.09LSB$ respectively. Also, fab-out chip was tested, analysed the cause of error operation, and proposed the field considerations for chip test.

• IE interfaces
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• v.21 no.2
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• pp.229-236
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• 2008

Recently, ubiquitous computing paradigm considers as a tool for making innovation and competitive strength in manufacturing industry like other industries. Particularly, the location-based service that enables us to trace real-time logistics make effective management of schedules for inventory control, facilities and equipments, jobs planning, and facilitate the processes of information management and intelligence, which relate with ERP and SCM in organizations. Our study tries to build the location-based system for products of semiconductors in manufacturing place and suggests the good conditions and effective tracking procedures for positions of products. Our study show that the system is good for the saving of time in tracking products, however, it has to be improved in terms of accuracy. The study verifies the application of RFID technology in manufacturing industry and suggests the improvement of photograph process through RFID. In addition, our research introduces the future operation of FAB in semiconductors' processes that relate with real-time automation and RFID in manufacturing company.

• Journal of Appropriate Technology
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• v.6 no.2
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• pp.126-135
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• 2020

Recently, with the development of the 4th Industrial Revolution era and the popularization of technologies the maker movement is spreading worldwide in various ways for education, entrepreneurship, and solving social problems. This paper introduces a case of establishing and operating a maker space in Tanzania, East Africa, one of the developing countries. iTEC Tech-shop was established in the first half of 2018 at the Nelson Mandela African Institution of Science and Technology (NM-AIST) in Arusha, Tanzania by Innovative Technology and Energy Center (iTEC), and has been operating for nearly two years. With the allocation of empty warehouse space from NM-AIST, physical facilities were established through the purchase and installation of equipment and hand tools. Based on the advice from Idea Factory of Seoul National University and Fab-Lab Seoul, iTEC Tech-shop operational system were established. Through a total of 7 technical workshops, iTEC Tech-shop provided training courses for about 180 local personnel. In addition, the smart Techshop test-bed project was promoted in order to improve the operation level along with securing sustainability of the Techshop. The case of the iTEC Tech-shop could be a useful case for institutions or organizations promoting the maker movement to developing countries.