• Transactions of Materials Processing
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• 제30권1호
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• pp.27-34
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• 2021

In this study, response surface method (RSM) was used in modeling and multi-objective optimization of the parameters of AA5052-H32 in incremental sheet forming (ISF). The goals of optimization were the maximum forming angle, minimum thickness reduction, and minimum surface roughness, with varying values in response to changes in production process parameters, such as tool diameter, tool spindle speed, step depth, and tool feed rate. A Box-Behnken experimental design (BBD) was used to develop an RSM model for modeling the variations in the forming angle, thickness reduction, and surface roughness in response to variations in process parameters. Subsequently, the RSM model was used as the fitness function for multi-objective optimization of the ISF process based on experimental design. The results showed that RSM can be effectively used to control the forming angle, thickness reduction, and surface roughness.

• Archives of Plastic Surgery
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• 제45권1호
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• pp.23-28
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• 2018

Background Condylar process fractures account for one-third of all mandibular fractures, and the distal fragment is prone to dislocate to the medial side due to the pulling of the lateral pterygoid muscle. Retromandibular approaches are commonly used, but the intraoperative view becomes limited in medially dislocated fractures. This study summarized a series of cases of retromandibular reduction for medially dislocated condylar process fractures and described our supplementary procedure to realign the dislocated condylar process. Methods Nine patients with medially dislocated condylar process fractures underwent surgical correction from January 2012 to December 2016. In 6 of them, it was possible to realign the fractures with a conventional retromandibular approach, but for 3 cases of severe dislocation to the middle cranial fossa, a supplementary transoral procedure was carried out. The angle difference between the ramus and condyle, ramus height, and maximal mouth opening (MMO) were evaluated. Results All 9 cases were restored to the proper anatomical alignment without any major complications, and postoperative images revealed successful union. The angle difference was $8.94^{\circ}{\pm}4.11^{\circ}$ preoperatively, and $0.99{\pm}0.49^{\circ}$ at the 6-month follow-up. The pretreatment ramus height difference was $6.12{\pm}6.09mm$, and the postoperative difference was $0.18{\pm}0.10mm$. These changes after surgery were statistically significant. The MMO before surgery was $11.44{\pm}3.0mm$, and the postoperative MMO was $37.2{\pm}2.9mm$, reflecting a significant increase after reduction. Conclusions Retromandibular reduction is a useful method in medially dislocated condylar process fractures, and additional transoral assistance should be considered to realign condylar processes that severely dislocate to the middle cranial fossa.

• Transactions of Materials Processing
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• 제14권8호통권80호
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• pp.704-711
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• 2005

The influence of process parameters in drawn wire on residual stresses was investigated. Based on a FE-simulation of the wire drawing process, the effects of process parameters such as semi-die angle, reduction, friction coefficient and bearing length on the residual stresses were investigated. The validity of the FE-simulation results was verified by the comparison of the previous simulated results with experimental data. In this study, semi-die angle and die reduction have significant effect on the residual stresses at the surface of drawn wire. Several methods such as, addition of axial tension, application of skin pass, straightening in multi-roll straightener etc, were suggested in the previous studies to reduce the residual stresses. In this study, the results show that the concurrent application of skin pass with low die reduction and low semi-die angle at the final stage of drawing operation reduces dramatically the both axial and hoop residual stresses after drawing

• Journal of Powder Materials
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• 제13권4호
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• pp.269-277
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• 2006

[ ${\beta}-W(W_3O)$ ] oxide layer on the surface of each W(tungsten) nanopowder produced by the electric explosion of wire(EEW) process were formed during the 1vol.% air passivation process. The oxide layer hindered sintering densification of compacts during SPS process. The oxide phase was reduced to the pure W phase during SPS. The W nanopowder's compacts treated by the hydrogen reduction showed high sintered density of 94.5%. after SPS process at $1900^{\circ}C$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• 제36권2호
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• pp.54-59
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• 2004

The methods for the minimization of fresh water consumption, waste water generation and water contamination have been greatly investigated and developed for last ten years. Recently, the rising cost of waste water treatment and the more strict environmental regulation lead to the higher demand of more efficient and systematic methods for process water management. The water reuse technology, which not only reduce the process water needs but also minimize waste water generation within the process, could be one of most efficient way for current demand. In this study, the practical way for reduction of water pollution and optimal reuse or recycle of process water in a newsprint mill was investigated by using a simulation model. The result of computer simulation showed that the COD level of approach system could be reduced by 50% after the stock concentration at the 2nd disc filter was increased upto 30%. The application of WRDF(Wrinkled Rotary Drum Filter) to the newsprint mill was carried out with pilot scale. The process water treated by WRDF had enough cleanliness to substitute the forming fabric shower water with the PDF water, which could result in the 30% reduction in fresh water consumption.

• Journal of Powder Materials
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• 제14권3호
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• pp.173-179
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• 2007

In the metallothermic reduction (MR) process used to obtain tantalum powder in one batch, it is difficult to control the morphology and location of the tantalum deposits. On the other hand, an electronically mediated reaction (EMR) process is capable of overcoming this difficulty. The effect of using $K_2TaF_7$ as the raw material and sodium as the reducting agent on the characteristics of tantalum powder are investigated. As the temperature of the reduction varied from 1023K to 1223K, the powder particles obtained with MR were relatively large $({\sim}34{\mu}m)$, while those prepared via EMR were of uniform $(13{\mu}m)$. In the MR process, the Ta powder recovery rate increased from 37% to 83% at 1123K in constrat with EMR process.

• Resources Recycling
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• 제5권4호
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• pp.17-24
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• 1996

The computer simulation model was established to verify the applicability of smelting reduction concept to treatment of industrial wastes which becomes issue on the enviromental and recycling view point. Computer simulation model provides as following results. The increase of post combustion ratio(PCR) and heat transfer efficiency of PC energy(HTE) is effective ways to save energy. But, in order to increase PCR, recovery efficiency of post combustion energy(HTE) have to be higher than 85% HTE considering refractory life and saving energy together. Coke is most useful fuel source because it shows lowest dependence of PCR and low hydrogen content. The quality of hot metal of current process would be expected to the similar level with that of blast furnace. The utilization of scrap and Al dross can be also possible to maximize the advantages of current process which is high temperature and chemical dilution with hot metal and slag. In case of scrap, energy consumption was slightly increases because of heating up energy of scrap. Consquently, current process concept provides the possibility of intergrating recycles of industrial wastes materials such as EAF slag, coke oven dust, life terminated acidic refractory, aluminium dross and scrap by smelting reduction process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제16권5호
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• pp.385-389
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• 2003

There are four main components of the CMP process: polishing pad, slurry, elastic supporter, and pad conditioner. The polishing pad is an essential component to the reproducibility of polishing uniformity in CMP process. However, the polishing pad in recently using metal CMP raised the several points of high cost caused by the increase of cycle time and the many usage of slurry. It is necessary to develop the novel polishing pad which would lead the cost reduction by the higher pad life-cycle, minimized cycle time and lower slurry usage. The characteristics of polishing pad were studied on the effects of different sets of the Polishing pad, which can be applied to metal chemical mechanical polishing process for global planarization of multilevel interconnection structure. The main purpose of this experiment is cost reduction by the increase of pad life-time, the decrease of cycle time and the lower usage of slurry through the specific hard porous structured pad design. It is confirmed that the novel polishing pad made the slurry usage decrease to 60% as well as the pad life-time increase twice with the 25% improvement of removal rate. The polishing time could be decreased and it also helped the cycle time to diminish. It can be expected that this results will help both the process throughput and the device yield to be improved.

• Journal of the Korean Society of Safety
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• 제37권5호
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• pp.22-32
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• 2022

The domestic smart factory is being built and spread rapidly, mainly by mid-sized companies and large enterprises according to the government's active introduction and support policy. But these factories only promote production system and efficiency, so harmfulness and risk factors are not considered. Therefore, to derive harmful risk factors in terms of industrial safety for 12,983 government-supported smart factory workplaces from 2014 to 2019, industrial accident status analysis compared workplaces with automation facilities and government-supported workplaces with automation facilities. Also, to reduce risks associated with domestic smart factory processes, twenty government-supported workplaces with automation facilities underwent analysis, evaluating risks through a status survey using the process evaluation table. In addition, the status survey considered region, size, industry, construction level, and accident rate; the difference in risk according to the structure of the process was confirmed. Based on the smart factory process evaluation results, statistical analysis confirmed that serial, parallel, and hybrid structures pose different risk levels and that the risks of mixed structures are greater. Finally, safety control system application was presented for risk assessment and reduction in the smart factory process, reflecting the results of disaster analysis and actual condition investigation.

• Clean Technology
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• 제9권2호
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• pp.87-100
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• 2003

The aim of study was to suggest a methodology for applying cleaner production technology in dyeing & finishing process of textile materials. To accomplish cleaner production, we performed consulting activity in dyeing factory, which composed of following different procedures. First, we organized consulting team with specialists for dyeing, energy and chemicals, and visited dyeing companies for the purpose of doing basic investigation such as analysis of process, chemicals & effluents, condition of equipment and process flow of products. Environmental aspect of raw materials (dyestuff, chemicals) was assessed by TOC, COD, BOD, and effluent of that was assessed by TOC, COD, BOD, TDS and pH. Second, We find out the problems in dyeing&finishing process from the view point of dyeing process, energy, raw materials and process management by utilizing MB (material balance), LCA(Life Cycle Assessment), EB(Energy Balance). Third, we generated the solutions to achieve optimal process condition by brain storming method, and then implemented the solutions to each process. Finally, we determined their effectiveness after considering the results of repeating trials for the solutions. Cleaner production could be achieved by keeping optimal process conditions, equipment modification, improved production management, and on-site reuse or recycling.