• Membrane and Water Treatment
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• 제4권4호
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• pp.237-249
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• 2013

Ultra-pure water (UPW), a highly treated water free of colloidal material and of a conductivity less than 0.06 ${\mu}S$, is an essential component required by modern industry. One of the methods for UPW production is the electrodialysis-ion exchange (ED/IE) system, in which the electrodialysis (ED) process is used as a preliminary demineralization step. The IE step can be replaced with electrodeionization (EDI) to decrease the volume of post-regeneration lyes. In this paper, the electrodialysis process carried out to relatively low diluate conductivity was investigated and the costs of UPW production were calculated. The optimal value of desalination degree by ED in the ED/IE and ED/EDI systems was estimated. UPW unit costs for integrated ED/IE and ED/EDI systems were compared to simple ion exchange and other methods for UPW production (RO-IE, RO-EDI). The minimal UPW unit costs in ED/EDI integrated system were estimated as $0.37/$m^3$ for feed TDS 600 mg/L and $0.36/$m^3$ for feed TDS 400 mg/L at 64 $m^3/h$ capacity, which was lower than in the comparable ED/IE integrated system ($0.42-0.44/$m^3$). The presented results suggest that an ED/EDI integrated system may be economically viable.

• 한국기계가공학회지
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• 제17권4호
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• pp.1-8
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• 2018

In drilling Inconel 601, which is used for compressor cases in aircraft engines, a lot of cutting oil must be supplied. This prevents tools from wear and fracture due to the heat buildup resulting from the high-temperature resistance and toughness of this alloy. However, the cutting oil supply has compromised the machining environment. This has caused attention to shift to an environmentally friendly cutting fluid supply system called the Minimum Quantity Lubrication(MQL) system. The aim of this study was to find a more efficient drill processing method using MQL and to verify its performance. To that end, the properties of Inconel that make it difficult -to -drill were studied by a comparison with the drilling of SM45C. Specific factors (i.e., cutting force and tool wear) were examined in relation to the conditions in the MQL-based drilling system. Based on these results, a sealed cover and step feed were proposed as measures to increase the effectiveness of the MQL system. The efficiency of the proposed method was established.

• 설비공학논문집
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• 제23권4호
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• pp.281-286
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• 2011

The objective of this study is to optimize the four-bed six-step pressure swing adsorption(PSA) process for high purity $CH_4$ recovery from the biogas. The effects of P/F(purge to feed) ratio and cycle time on the process performance were evaluated. The cyclic steady-states of PSA process were reached after 12 cycles. The purity and recovery rate of product gas, pressure and temperature changes were constant as the cycle repeated. It was shown that the P/F ratio gave significant effect on the product recovery rate by increasing the amount of purge gas in purge and regeneration step. The optimal P/F ratio was found to be 0.08. As the cycle time increased, the product purity decreased by increasing the feed gas flow rate. It was found that the optimal operating conditions were P/F ratio of 0.08 and total cycle time of 1,440 seconds with the purity of 97%.

• 한국기계가공학회지
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• 제13권6호
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• pp.66-72
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• 2014

Incremental forming is a relatively novel sheet forming process, in which parts can be formed without the use of dedicated dies. In this paper, the influence of the process parameters (tool diameter, step size, feed rate, existence of a die, forming methods, and kinds of tool path) on surface roughness in the case in which parts are processed by incremental forming was discussed. Al 1050 material is used in the experiments. A table of orthogonal arrays is used to design the experiments and the ANOVA method is employed to statistically analyze the results. The obtained results show that the process parameters of tool diameter, step size, and the existence of a die have a significant effect on the surface roughness, whereas the feed rate, forming methods and kinds of tool path are insignificant.

• Membrane and Water Treatment
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• 제13권4호
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• pp.201-208
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• 2022

Emulsion Liquid Membrane (ELM) is a prominent technique for the separation of heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of the components (Surfactant and Carrier) of ELM is a very significant step for its preparation. In the ELM technique, the primary water- in-oil (W/O) emulsion is emulsified in water to produce water-in-oil-in-water (W/O/W) emulsion. The water in oil emulsion was prepared by mixing the membrane phase and internal phase. To prepare the membrane phase, the extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2- ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II). Emulsion Liquid Membrane (ELM) is a well-known technique for separating heavy metal ions from wastewater due to the fast extraction and is a single-stage operation of stripping-extraction. The selection of ELM components (Surfactant and Carrier) is a very significant step in its preparation. In the ELM technique, the primary water-in-oil (W/O) emulsion is emulsified to produce water-in-oil-in-water (W/O/W) emulsion. The water in the oil emulsion was prepared by mixing the membrane and internal phases. The extractant D2EHPA (di-2-ethylhexylphosphoric acid) was used as a mobile carrier, Span-80 as a surfactant, and Paraffin as a diluent. Moreover, the internal (receiving) phase was prepared by dissolving sulphuric acid in water. Di-(2-ethylhexyl) phosphoric acid such as surfactant concentration, carrier concentration, sulphuric acid concentration in the receiving (internal) phase, agitation time (emulsion phase and feed phase), the volume ratio of the membrane phase to the receiving phase, the volume ratio of the external feed phase to the primary water-in-oil emulsion and pH of feed were studied on the percentage extraction of metal ions at 20℃. The results show that it is possible to remove 78% for As(V), 98% for Cd(II), and 99% for Pb(II).

• 한국수소및신에너지학회논문집
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• 제17권1호
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• pp.8-20
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• 2006

For large scale separation hydrogen from different mixing ratio(60/40 and 80/20 vol.%) of hydrogen and methane $1Nm^3/hr$ and $4Nm^3/hr$ 2bed-6step pressure swing adsorption(PSA) process was used, respectively. The effects of the feed gas pressure, adsorption time, the feed flow rate and the P/F(purge to feed) ratio on the process performance were evaluated. In the $1Nm^3/hr$ PSA results, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75 % recovery and 99 % purity hydrogen in these processing. The optimum feed flowrate was 22 LPM and 17 LPM in the ratio 60/40 and 80/20, respectively. In the $4Nm^3/hr$ PSA results, 10 atm adsorption pressure might be simulated values to obtain more than 80 % recovery and 99 % purity hydrogen in these processing.

• 한국생산제조학회지
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• 제25권2호
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• pp.118-123
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• 2016

Overlap cutting is a fundamental method of applying abrasive water jet (AWJ) machining to milling to produce a wider surface because the nozzle outlet is approximately 1.0 mm wide. In this study, the effects of overlap cutting on the depth profile and surface roughness are investigated. The overlapping area depends on the amount of step over, which is controlled in the pick-feed direction. If the step over is equal to or larger than the diameter of the nozzle, no overlap cut occurs but large cusps remain between the cut paths. A step over as small as one-thirds of the nozzle diameter may lead to triple-overlap cutting resulting in an extraordinary depth. By using pocket milling experiments with a step over of 0.46 (or 0.47), it is verified that AWJ can produce a milled surface of titanium, one of the hard-to-cut materials, with $76{\mu}m$ Ra.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.406-409
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• 1997

An economical 4-axis CNC controller employing step motors is designed and implemented in this paper. By using the inherent ability of holding position of the motor, the CNC controller uses open-loop control for removing trajectory error and for a simple hardware. Each drive of axis has an 8-bit microprocessor 89C52 and a PC controls the axes and pendant by means of RS232C serial communication. Backlash is also compensated at the axis controller. While compensating the backlash, the feed rate becomes zero in order to minimize trajectory error. The trajectories of 16ms interval are computed on PC and are sent to motor drives. In the drives, the trajectories are linearly interpolated for 2ms interval. The developed CNC does not require add-on specific motion card on PC. From the experimental results, the validity of the CNC controller based on step motor is proved.

• Asian-Australasian Journal of Animal Sciences
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• 제20권12호
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• pp.1849-1857
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• 2007

The experiment was carried out using fistulated multiparous Holstein Friesian crossbred (75% Holstein Friesian and 25% Red Sindhi) dairy cows in their dry period fed on untreated rice straw to evaluate the nutritive value of local protein feed resources using the in sacco method and in vitro pepsin-pancreatin digestion. Experimental feeds were cottonseed meal (CSM); soybean meal (SBM); dried brewery's grains (DBG); palm kernel meal (PSM); cassava hay (CH); leucaena leaf meal (LLM). Each feedstuff was weighed into duplicate nylon bags and incubated in each of the two rumen fistulated cows for 0, 2, 4, 8, 16, 24, and 48 h. Rumen feed residues from bags of 16 h incubation were used for estimation of lower gut digestibility by the technique of in vitro pepsin-pancreatin digestion. Ruminal ammonia-nitrogen ($NH_3-N$) concentrations did not differ between treatments or time with a mean of 5.5 mg%. Effective degradability of DM of CSM, SBM, DBG, PSM, CH and LLM were 41.9, 56.1, 30.8, 47.0, 41.1 and 47.5%, respectively. Effective degradabilities of the CP in feedstuffs were 49.6, 59.2, 40.9, 33.5, 47.3 and 65.0% for the respective feedstuffs. The CP in vitro pepsin-pancreatin digestibility as ranked from the highest to the lowest were SBM, CSM, LLM, CH, DBG, PSM, respectively. The intestinal and total tract digestion of feedstuffs in the current study were relatively lower than that obtained from previous literature. The results of this study indicate that SBM and LLM were highly degradable in the rumen, while CH, CSM and DBG were less degradable and, hence resulted in higher rumen undegradable protein. Soybean meal and LLM could be used to improve rumen ecology whilst CH, CSM and DBG could be used as rumen by-pass protein for ruminant feeding in the tropics.

• Animal Bioscience
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• 제34권6호
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• pp.967-974
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• 2021

Objective: The objective of this study was to estimate the genetic correlation (rpc) of growth performance between purebred (Duroc and Korean native) and synthetic (WooriHeukDon) pigs using a single-step method. Methods: Phenotypes of 15,902 pigs with genotyped data from 1,792 pigs from a nucleus farm were used for this study. We estimated the rpc of several performance traits between WooriHeukDon and purebred pigs: day of target weight (DAY), backfat thickness (BF), feed conversion rate (FCR), and residual feed intake (RFI). The variances and covariances of the studied traits were estimated by an animal multi-trait model that applied the Bayesian inference. Results: rpc within traits was lower than 0.1 for DAY and BF, but high for FCR and RFI; in particular, rpc for RFI between Duroc and WooriHeukDon pigs was nearly 1. Comparison between different traits revealed that RFI in Duroc pigs was associated with different traits in WooriHeukDon pigs. However, the most of rpc between different traits were estimated with low or with high standard deviation. Conclusion: The results indicated that there were substantial differences in rpc of traits in the synthetic WooriHeukDon pigs, which could be caused by these pigs having a more complex origin than other crossbred pigs. RFI was strongly correlated between Duroc and WooriHeukDon pigs, and these breeds might have similar single nucleotide polymorphism effects that control RFI. RFI is more essential for metabolism than other growth traits and these metabolic characteristics in purebred pigs, such as nutrient utilization, could significantly affect those in synthetic pigs. The findings of this study can be used to elucidate the genetic architecture of crossbred pigs and help develop new breeds with target traits.