• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.506-511
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• 1996

The performance evaluation of flexible manufacturing systems or cells at the stages of design and planning is one of important issues in manufacturing. For that reason, Guo has presented an approachbased on moment generating function and generalized stochastic PetriNets for performance analysis. In this paper, Buo's approach is extended tothe cases of flexible manufacturing cell including one machining center with a local buffer, AS/RS(Automatic Storage and Retrieval System), set-up station and AGV(Automated Guided Vehicle). Then the performance measures from this approach is compared with simulation. The major advantage ofthis method over existing performance evaluation methods is the ability to compute analytic solutions for performance measures.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.1
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• pp.94-100
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• 1997

본 연구에서는 자동화된 VLSI 제조 시스템 환경에서의 로트 조정기 및 범용 셀 제어기의 구축에 필요한 새로운 소프트웨어 구조 및 프로토콜을 제시하였다. 반도체 제조 시스템의 운용 제어 활동은 로트 조정기와 범용 셀 제어기가 상호 협조적으로 통신하는 클라이언트/서버 구조로 모형화 되었으며, 로트 조정기는 하나 이상의 작업을 수행할 수 있는 범용 셀 제어기에 작업을 의뢰하는 클라이언트로서 작동된다. 반도체 제조 시스템의 운용 소프트웨어와 관련된 기존의 연구들이 개념적인 구조와 전략 만을 다루었던 것과는 달리, 본 연구에서는 생산 설비 뿐만 아니라 물류운반 장치의 제어를 위하여 상세한 수준에서의 설계가 제시되었다. 본 연구의 특징으로는 설비 구성, 로트 형태, 일정 계획 규칙 등의 변경에 대한 동적 재구성 가능성을 들 수 있다. 또한 제안된 설계는 상용화된 프로세스 통신 기능을 사용하여 구현이 용이하다.

• Transactions of Materials Processing
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• v.15 no.3 s.84
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• pp.247-254
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• 2006

Rather than traditional manufacturing processes, miniature manufacturing processes usually require sophisticated equipments and characteristics of the processes of high cost and of low productivity. Contrarily, miniature stamping process can be realized in a low cost high productivity with relatively inexpensive equipments. In the meso scale, mechanical properties, especially work hardening characteristics, are discovered to be statically scattered and size dependent by intensive experimental and numerical investigations, which make the stamping process hard to apply to the miniature manufacturing. In this study, dual purpose experimental device that can be used for both miniature scale tensile test and miniature scale stamping by simple change of attachment has been developed. For the tensile test, the elongation has been measured with a combined use of a CCD camera and a linear encoder in order to account for the possibility of slippage between specimen and the grip and to ensure the accuracy of the measurement, while load has been measured with a load cell. To satisfy the required material properties for stamping, optimal annealing condition has been found by examining the microstructure of annealed specimen.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.351-362
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• 1999

버퍼는 생산시스템에서 시스템내의 기계고장, 프로세스시간의 변화, 그리고 부품들의 이동경로의 복잡성 등과 같은 요인들로 인해 발생 가능한 blocking현상과 starving현상을 감소시키는데 사용되고 있다. 유연 생산시스템(Flexible Manufacturing System)에서는 버퍼의 단위당 비용이 높아 시스템내의 총 버퍼 크기는 제한적이어서, 적절한 버퍼 관리를 통해 시스템 효율성을 향상시킬 수 있다. 본 연구는 이러한 버퍼의 특성을 분석하고 AGVS(Automated Guided Vehicle System)을 사용하는 다중셀방식의 FMS(multi-cell Flexible Manufacturing Systems) 환경에서의 버퍼관리와 관련된 기존 연구들을 검토하고, 새로운 개념의 가상시스템버퍼를 소개한다.

• Journal of the Korea Furniture Society
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• v.20 no.5
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• pp.490-503
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• 2009

The objective of this work was to investigate the mechanism of heat transfer in hot-pressing process for MDF manufacturing by reference study. Firstly, general heat transfer theory was studied. The numerical analysis of heat transfer in hot-pressing process was studied on temperature profile, moisture profile, physical properties between moisture and board. The mechanism of heat and moisture transfer inside of board was analyzed by conduction, convection, radiation and diffusion of bound water in wood cell walls. Especially, the change of core temperature as hot press time was important factor to setup hot-pressing schedule in MDF manufacturing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.724-728
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• 2005

Electro-optic characteristics of reflective hybrid aligned liquid crystal (LC) cell driven by fringe field using a nematic LC with positive dielectric anisotropy have been studied. Optimized optical configurations are achieved by using a single polarizer, half-wave film and a cell with quarter-wave retardation. The simulation results shows an optimum cell retardation of $0.30{\mu}m$. This value may allow a practical cell gap larger than $3{\mu}m$, which makes it easy to control in the manufacturing process. Furthermore, this LC cell with optimized cell parameters shows low wavelength dispersion and the contrast ratio greater than 5 over exists about $100{\circ}$ in vertical direction and $160{\circ}$ in horizontal direction. Also, when using the LC with positive dielectric anisotropy rather than negative dielectric anisotropy, the display shows low power consumption and fast response time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.11
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• pp.699-704
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• 2017

The amount of electric power for photovoltaic power generation depends on the location of the power plant and the direction of solar cell. The solar cell controls the generation of solar power plants. Therefore, the structure of solar cell, manufacturing method, and optic technology were factors contributing to increased solar cell efficiency; however, the technical limit has been reached. Herein, we propose a new method to increase the solar cell efficiency using a wavelength conversion technology that converts ultraviolet and infrared rays, which are not effectively used in solar cells, into effective wavelength of solar cell. We used fluoride $Na(Ca)YF_4$ phosphor for wavelength conversion. Then, a wavelength-conversion fluorescent paste, prepared using an organic-silicon binder, was used to prepare a film that was applied to Si solar cells. It was confirmed that conversion efficiency improved by 5% or more.

• Current Photovoltaic Research
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• v.5 no.1
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• pp.33-37
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• 2017

Today, photovoltaic power generation mostly uses Si crystalline solar cell modules. The most vulnerable part of the Si solar cell module is that the power generation decreases due to the temperature rise. But, it is widely used because of low installation cost. In the solar market, where Si crystalline solar cell modules are widely used. The CPV (Concentrated Photovoltaic) module appeared in the solar market. The CPV module reduces the manufacturing cost of the solar cell by using non-Si in the solar cell. Also, there is an advantage that a rise in temperature does not cause a drop in power generation. But this requires high technology to install and has a disadvantage that the initial installation cost is expensive compared to normal Si solar cell module. So that we built a testbed to see these characteristics. The testbed was used to measure the amount of power generation in a long-term outdoor environment and compared with the general Si solar cell module.

• Microbiology and Biotechnology Letters
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• v.36 no.3
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• pp.173-181
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• 2008

Bovine blood, cell, tissue, and organ are used as raw materials for manufacturing biologics such as biopharmaceuticals, tissue-engineered products, and cell therapy. Manufacturing processes for the biologics have the risk of viral contamination. Therefore viral validation is essential in ensuring the safety of the products. Bovine parvovirus (BPV) is one of the common bovine pathogens and has widely been known as a possible contaminant of biologics. In order to establish the validation system for the BPV safety of biologics, a real-time PCR method was developed for quantitative detection of BPV contamination in raw materials, manufacturing processes, and final products. Specific primers for amplification of BPV DNA were selected, and BPV DNA was quantified by use of SYBR Green 1. The sensitivity of the assay was calculated to be $1.3{\times}10^{-1}\;TCID_{50}/mL$. The real-time PCR method was validated to be reproducible and very specific to BPV. The established real-time PCR assay was successfully applied to the validation of Chinese hamster ovary (CHO) cell artificially infected with BPV. BPV DNA could be quantified in CHO cell as well as culture supernatant. Also the real-time PCR assay could detect $1.3{\times}10^0\;TCID_{50}/mL$ of BPV artificially contaminated in bovine collagen. The overall results indicated that this rapid, specific, sensitive, and robust assay can be reliably used for quantitative detection of BPV contamination during manufacture of biologics.

• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.34-42
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• 2008

Bovine blood, cell, tissue, and organ are used as raw materials for manufacturing biologics such as biopharmaceuticals, tissue engineered products, and cell therapy. Manufacturing processes for the biologics using bovine materials have the risk of viral contamination. Therefore viral validation is essential in ensuring the safety of the products. Bovine viral diarrhoea virus (BVDV) is the most common bovine pathogen and has widely been known as a contaminant of biologics. In order to establish the validation system for the BVDV safety of biologics, a real-time RT-PCR method was developed for quantitative detection of BVDV contamination in raw materials, manufacturing processes, and final products. Specific primers for amplification of BVDV RNA was selected, and BVDV RNA was quantified by use of SYBR Green I. The sensitivity of the assay was calculated to be 1 $TCID_{50}/mL$. The rent-time RT-PCR method was validated to be reproducible and very specific to BVDV. The established real-time RT-PCR assay was successfully applied to the validation of Chinese hamster ovary (CHO) cell artificially infected with BVDV. BVDV RNA could be quantified in CHO cell as well as culture supernatant. Also the real-time RT-PCR assay could detect $10TCID_{50}/mL$ of BVDV artificially contaminated in bovine collagen.