• 청정기술
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• 제4권1호
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• pp.6-23
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• 1998

반도체 산업은 각종 전자지기의 발달로 급격히 성장하였으며 현재는 우리 나라에서도 반도체 산업이 경제에서 큰 비중을 차지하고 있다. 국내외의 환경규제와 환경에 대한 대중의 관심이 높아지면서, 반도체 공정의 안전한 관리와 환경유해성 물질의 배출억제를 위하여 반도체 산업에서의 청정기술의 개발이 시급한 과제가 되고 있다. 청정기술이란 근본적으로 환경유해성 오염물질을 배출하지 않는 기술을 의미하나 이는 지금까지 개발된 기술로는 거의 불가능하다. 따라서 공정 내에서부터 환경유해물질의 배출을 최소화하는 기술도 청정기술의 범위에 포함시킨다. 반도체 공정은 연속적인 화학공정들로 구성되어 있으며 그 과정에서 많은 종류의 환경유해성 오염물질이 배출될 수 있다. 반도체 공정에서 발생하는 오염물질들은 기상 형태의 배가스, 액상 형태의 폐수, 폐기물의 세 가지 형태로 나누어 볼 수 있다. 기상의 오염물질을 억제하기 위한 기술로는 오염물질만을 선택적으로 파괴하거나 오염물질만을 농축하여 공정 내에서 재활용하는 방법, 또는 오염을 유발하는 물질 대신 이를 대체할 수 있는 환경에 안전한 물질을 개발하는 방법 등이 있다. 액상의 오염물질을 저감시키는 기술로는 공정의 최적화를 통하여 오염물질의 양을 최소화하는 방법과 유독한 물질로 구성된 원료를 대체하는 방법 등이 있다. 또한 근본적인 오염원을 제거하기 위하여 화학물질의 사용량 자체를 줄이거나 기상을 이용한 세정 시스템 등의 방법을 사용하는 것도 연구중이다.

• Korean Chemical Engineering Research
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• 제56권6호
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• pp.878-883
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• 2018

A circulating fluidized bed (CFB) has been used in various chemical industries because of good heat and mass transfer. In addition, the methanol to olefins (MTO) process requiring the CFB reactor has attracted a great deal of interest due to steep increase of oil price. To design a CFB reactor for MTO pilot process, therefore, we has examined the hydrodynamic properties of spherical catalysts with different particle size and developed a correlation equation to predict catalyst holdup in a riser of CFB reactor. The hydrodynamics of micro-spherical catalysts with average particle size of 53, 90 and 140 mm was evaluated in a $0.025m-ID{\times}4m-high$ CFB riser. We also developed a model described by a decay coefficient to predict solid hold-up distribution in the riser. The decay coefficient developed in this study could be expressed as a function of Froude number and dimensionless velocity ratio. This model could predict well the experimental data obtained from this work.

• 한국안전학회지
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• 제13권1호
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• pp.98-104
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• 1998

Recently, industrial accidents have occurred in various patterns due to the diversity of industries and the integration of facilities. Especially, the major accidents affect broad area and result in huge loss of lives and properties. Domestic researches on techniques for keeping away from such hazardous danger have been actively performed but their activities are limited in some institutes and universities. In advanced countries, integrated management systems like Seveso Directive of EU and OSHA(Occupational Safety and Health Act) of U.S.A. have been legislated along with the systematic research activities. In Korea, the integrated safety management systems called SMS(Safety Management System) and PSM(Process Safety Management) have been applied to major industries. These systems made chemical industries manage the process safety information by collecting and arranging safety data by themselves. In order to implement the system successfully, it is urgently required to prepare a tool for searching and accumulating process safety data systematically. In this study, a computerized prototype of Risk Assessment System which is essential to SMS and PSM was developed as a main system and data base as subsystem to handle safety information.

• 한국안전학회지
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• 제28권1호
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• pp.40-46
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• 2013

In the chemical process industries, accidents have a high potential and large effects on catastrophic results. Therefore the safety management for accident prevention plays a crucial role to guarantee the process safety. For these reasons, many systematic methods for safety management system have been widely employed in the fields of chemical processes. PSM (Process safety management) is one of most representative methods. The audit system, which is one of PSM system components, evaluates the performance of PMS system. However, most existing safety audit systems are not systematic and these are performed based on knowledges and experiences of various specialist. Moreover, the safety audit is only performed based on each independent technical component. So, the results of safety audit are not a quantitative index but only a series of commentaries. Finally, it is very difficult to obtain the comparison with other plants or industries. In this study, the novel systematic method and index-based accident database of auditing safety management systems for quantitative assessment are proposed. First, the elements of safety audit replace technical methods to categories of accident database. The F-N curve of each category for accident database is employed to derive the index for quantitative assessment. The Accidental Factor Risk Index (AFRI) is suggested for evaluating the effect of each element in accident database and safety audit system. The safety audit can be modified according to the proposed index.

• Macromolecular Research
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• 제13권5호
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• pp.427-434
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• 2005

To improve the performance and reduce raw material costs, blocked isocyanates were prepared with mixture of blocking agents in many industries. Three blocked isocyanates (adducts) namely $\varepsilon$-caprolactam/benzotriazole-blocked 4,4'-diphenylmethane diisocyanate (MDI), toluene-2,4-diisocyanate (TDI) and 4,4'-dicyclohexyl-methane diisocyanate ($H_{12}$MDI) were synthesized. Six reference adducts were also prepared by blocking MDI, TDI, and $H_{12}$MDI with $\varepsilon$-caprolactam ($\varepsilon$-CL) or benzotriazole. The reactions were carried out in acetone medium and dibutyltin dilaurate (DBTDL) was used as a catalyst. The progress of the blocking reaction was monitored by IR spectroscopy. De-blocking temperatures (dissociation temperatures) of these adducts were studied using DSC and TGA and the results were correlated. As expected, the thermal analysis data showed that de-blocking temperature of blocked aromatic isocyanates was lower than that of the blocked aliphatic isocyanates. The low de-blocking temperature of blocked aromatic isocyanate could be due to electron withdrawing benzene ring present in the blocked isocyanates. It was also found that benzotriazole-blocked adducts de-blocked at higher temperature compared with $\varepsilon$-CL-blocked adducts.

• 제어로봇시스템학회논문지
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• 제12권12호
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• pp.1178-1183
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• 2006

This paper is concerned with the modeling and identification of pH neutralization process as nonlinear chemical system. The pH control has been applied to various chemical processes such as wastewater treatment, chemical, and biochemical industries. But the control of the pH is very difficult due to its highly nonlinear nature which is the titration curve with the steepest slope at the neutralization point. We apply SVM which have become an increasingly popular tool for machine teaming tasks such as classification, regression or detection to model pH process which has strong nonlinearities. Linear and radial basis function kernels are employed and each result has been compared. So SVH based on kernel method have been found to work well. Simulations have shown that the SVM based on the kernel substitution including linear and radial basis function kernel provides a promising alternative to model strong nonlinearities of the pH neutralization but also to control the system.

• 기술사
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• 제43권2호
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• pp.60-63
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• 2010

This analysis introduces a lube oil circulation system for a big reducer in the chemical process industries. We have been operating the system and found out that the system greatly helped us save the maintenance cost by increasing the lifetime of the reducer.

• 한국가스학회지
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• 제17권3호
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• pp.33-38
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• 2013

화학공장은 다량의 화학물질을 사용하기 때문에 사고가 발생하면, 많은 피해가 발생한다. 따라서 사고를 예방하기 위하여 위험성평가를 실시하고 있다. 화학공정은 HAZOP 기법을 이용하여 위험성평가를 실시하고 그 결과를 많이 활용하고 있다. 이 연구에서는 HAZOP 기법과 Bow-Tie 기법을 분석하고, Bow-Tie 위험성평가를 수행하였으며, 그 결과 다른 위험성평가에서 발견할 수 없었던 위험성이 도출되었고, 그 위험성을 제거하기 위한 14개의 개선사항이 도출되었다. Bow-Tie 위험성평가가 현장의 적용성과 위험요인을 도출하고 개선대책을 수립하는데 적합하다는 것을 확인하였다.

• Advances in nano research
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• 제12권4호
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• pp.387-403
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• 2022

Silica nanoparticles, which have a broad range of sizes and specific surface features, have been used in many industrial applications. This study was conducted to synthesize monodispersed silica nanoparticles directly from tetraethyl orthosilicate (TEOS) with an alkaline catalyst (NH₃) based on the sol-gel process and the Stöber method. A central composite design (CCD) is used to build a second-order (quadratic) model for the response variables without requiring a complete three-level factorial experiment. The process was then optimized to achieve the minimum particle size with the lowest concentration of TEOS. Dynamic light scattering and scanning electron microscopy were used to analyze the size, dispersity, and morphology of the synthesized nanoparticles. After optimization, a confirmation test was carried out to evaluate the confidence level of the software prediction. The results revealed that the predicted optimization is consistent with experimental procedures, and the model is significant at the 95% confidence level.

• 한국분말재료학회지
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• 제8권3호
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• pp.210-213
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• 2001

$Si_3N_4$/TiN nano/nano-type composites were successfully fabricated by the combination of a mechano-chemical grinding (MCG) method and a short time sintering process, and their wear resistance was evaluated. Powder mixtures of $\alpha-Si_3N_4$and Ti were prepared using mechano-chemical grinding process and the resulting nanocomposite powder mixtures were consolidated using pulsed electric current sintering (PECS). TEM observation showed that the nano/nano-type composites consisted of homogeneous and very fine matrix grains with the size less than 100 nm. The obtained $Si_3N_4$-based nano/nano-type showed high wear resistance and electric discharge machinability.