• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.1-11
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• 2016

The effect of the migration of nanoparticles near the wall of a channel on the convective heat transfer in a laminar flow of $SiO_2$ nanoparticle suspensions (nanofluids) under constant wall heat flux boundary conditions was numerically and experimentally investigated in this study. The dynamic thermal conductivity of the aqueous $SiO_2$ nanofluids was measured using T-type thermocouples attached to the outer surface of a stainless steel circular tube (with a length of 1 m and diameter of 1.75 mm). The nanofluids used in this study were synthesized by dispersing $SiO_2$ spherical nanoparticles with a diameter of 24 nm in de-ionized water (DIW). The enhancement of the thermal conductivity of the nanofluids (e.g., an increase of up to 7.9 %) was demonstrated by comparing the temperature profiles in the flow of the nanofluids with that in the flow of the basefluids (i.e., DIW). However, this trend was not demonstrated in the computational analysis, because the numerical models were based on continuum assumptions and flow features involving nanoparticles in a stable colloidal solution. Thus, to explore the non-continuum effects, such as the modification of the morphology caused by nanoparticle-wall interactions on the heat exchanging surfaces (e.g., the isolated and dispersed precipitation of the nanoparticles), additional experiments were performed using DIW right after the measurements using the nanofluids.

• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.168-173
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• 2021

In this study, we measured total flavonoids after extracting the total flavonoids from lemongrass which is known to have a high content of antioxidant ingredients when using microwave energy. Also, optimal extraction conditions of active ingredients using central composite design-response surface methodology (CCD-RSM) were presented. Both ultrapure water and alcohol were used as extraction solvents and the volume ratio of ethanol/ultrapure water, microwave irradiation time, and microwave irradiation power were set as independence variables. And the extraction yield and total flavonoids were measured. The optimal extraction conditions using CCD-RSM were the volume ratio of ethanol/ultrapure water = 56.3 vol.%, the microwave irradiation time = 6.1 min, and the microwave irradiation power = 574.6 W. We could also obtain expected results of yield = 17.2 wt.% and total flavonoids = 44.7 ㎍ QE/mL dw under the optimum conditions. The comprehensive satisfaction degree of this formula was 0.8562. The P-value was calculated for the yield of 0.037 and the total flavonoids content of 0.002. The average error from actual experiments established for the verification of conclusions was lower than 2.5%. Therefore, a high favorable level could be obtained when the CCD-RSM was applied to the optimization of extraction process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.28-35
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• 2007

Currently, most of all valves using at the semiconductor & LCD manufacturing process are packless type. Such valves are needed to have the functions to protect perfectly from the leakage of fluid by using bellows and diaphragm instead of the grand packing. But not only those valves made in Korea are not available at this point, but also advanced foreign manufacturers do not open enough their data on the basic technology. Otherwise although they open the data a little, they are almost data about stainless steel for pneumatic valves. In this paper, it was focused on the fluid valves for chemical & DI water based on the data of steel valves which are already using commercially. And also this study concentrated to collect the basic developing data of Eco-On/Off diaphragm valve by ourselves.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.55-59
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• 2010

In this study, we developed nonvolatile residue (NVR) real-time monitoring system to measure the nonvolatile residue particle in ultra pure water (UPW). This device has a capability of measuring 4 different channels, i.e., 10 nm, 30 nm, 50 nm, and 100 nm. Until now, the light scattering method to detect RAE(residue after evaporation) was the only choice. However, this method can detect RAE larger than ca. 50 nm. In ultra pure water, RAE particles are usually very small and hard to detect with conventional laser scattering devices. To detect very small RAEs, a new system is developed and tested. The system consists of an atomizer that generates RAE particles and a four channel condensation particle counter (CPC). During the several months' operation in manufacturing line, the system was successfully tested and showed reliable results.

• Clean Technology
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• v.8 no.4
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• pp.205-215
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• 2002

Can industry has grown up with growth of packing industry and its recycling activation in recent years. But profit has became low by oversupply. Therefore, can industry needs a reduction of environmental load and official loss by an optimization of process in order to maintain its competitiveness. In this study, the main issues of aluminium can production was investigated by life cycle assessment. As a result of LCA, it examined closely by main issues that reduce defective cans and remove tramp oil. In the present work, it was recommended that setup of R/O system, sterillizing tramp oil separation, and heating system of DI water. The ROI investigated 6.4 months. The operating cost with the advanced processes could be reduced annually by 300 million won.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.442-447
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• 2017

In this study, we extracted an antioxidant from natural products which are known to have a high antioxidant content and also optimized the extraction process by applying a response surface methodology (RSM). In addition, by measuring the total flavonoids and total polyphenols of the active ingredient extracted persimmon leaf and thistle, the functionality of the active ingredient was evaluated. Both ultrapure water and alcohol were used as extraction solvents and the ratio of ultrapure and alcohol, amount of sample, extraction time, extraction temperature were set as independence variables. Also, the yield, total polyphenols, and flavonoids was set as the response. Optimal extraction conditions were as follows; for persimmon leaf, the extraction time = 3.1 h, ratio of alcohol/ultrapure = 63.4 vol%, and temperature = $54.6^{\circ}C$ while for thistle the extraction time = 2.9 h, ratio of alcohol/ultrapure = 40.7 vol%, and temperature = $68.4^{\circ}C$. Also, the response were as follows; for persimmon leaf, the yield = 27.7%, total polyphenols = 33.2 mg GAE/g, and total flavonoids = 47.8 mg QE/mg dw, whereas for thistle the yield = 27.0%, total polyphenols = 17.9 mg GAE/g, and total flavonoids = 28.8 mg QE/mg dw at the optimal conditions. The overall satisfaction level was 71.7%.

• Applied Chemistry for Engineering
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• v.29 no.4
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• pp.446-451
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• 2018

Effective ingredients were extracted using wheat sprout with high levels of flavonoids, and the extraction process was optimized with a central composite design model. The response value of the central composite design model establishes the extraction yield and the content of the flavonoids. The main and interactive effects were then analyzed depending on independent variables such as the extraction time, the volume ratio of alcohol to ultrapure water, and the extraction temperature. The extraction time and temperature were relatively large for the extraction yield. For the total flavonoids, the extraction time was most significantly affected. Considering both the extraction yield and the content of the total flavonoids, optimal extraction conditions were as follows: the extraction time (2.44 h), volume ratio of alcohol to ultrapure water (50.00 vol%), extraction temperature ($54.41^{\circ}C$). Under these condition, the extraction yield was 30.14 wt% and the content of the total flavonoids was $35.37{\mu}g\;QE/mL\;dw$. From the actual experimental result, the extraction yield under this condition was 29.92 wt% and the content of the total flavonoids was $35.32{\mu}g\;QE/mL\;dw$, which had an error rate of 0.39% and 0.74%, respectively. This is a multi-analysis comprehensive analysis that analyzes two simultaneous values of responses, but is considered to be highly accurate and also provides an excellent reliability of the optimization process in this study.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.248-254
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• 2024

In this study, functional substances with antibacterial properties were extracted from the needles of Abies holophylla and Pinus koraiensis, and optimized using the central composite design-response surface methodology (CCD-RSM). The optimal extraction conditions for Abies holophylla were an extraction temperature of 59.5 ℃ and an ethanol/ultrapure water volume ratio of 69.5 vol.%, resulting in an extraction yield of 13.5% and inhibition diameters of 11.6 mm against Escherichia coli (E. coli) and 9.3 mm against Staphylococcus aureus (S. aureus). For Pinus koraiensis, the optimal extraction conditions were an extraction temperature of 59.2 ℃ and an ethanol/ultrapure water volume ratio of 67.8 vol.%, resulting in an extraction yield of 4.8% and inhibition diameters of 7.9 mm against E. coli and 12.5 mm against S. aureus. The actual experimental results under these optimal conditions showed that an extraction yield from Abies holophylla needles was 13.0% and an inhibition diameter of 11.7 mm against E. coli and 9.2 mm against S. aureus, indicating an error rate of approximately ± 2.3%. For Pinus koraiensis needles, the extraction yield was 5.1%, with inhibition diameters of 7.5 mm against E. coli and 12.3 mm against S. aureus, indicating an error rate of ± 4.23%.

• Applied Chemistry for Engineering
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• v.35 no.3
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• pp.222-229
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• 2024

The use of low-toxic, hypoallergenic, and environmentally friendly natural pigments has increased. With growing interest in health, research on natural extracts containing beneficial substances for the human body is actively underway. In this study, natural pigments were extracted from sprout barley using a solvent extraction method and CCD-RSM was used to optimize the extraction process. The experiment's independent variables included extraction temperature, alcohol/ultra-pure volume ratio, and extraction time. The response variables were set to achieve a target chromaticity (L = 45, a = -35, b = 45), and to maximize DPPH radical scavenging activity evaluating the antioxidant capacity. The statistical significance of the main effect, interaction effect, and effect on the response value was evaluated and analyzed through the F and P values for the regression equation variables calculated using RSM optimization. Additionally, the reliability of the experiment was also confirmed through the P values of the probability plot graph. The extraction conditions for optimizing the four reaction values are 76.1 vol.% alcohol/ultra pure water volume ratio, an extraction temperature of 52.9 ℃ , and an extraction time of 49.6 min. Under these conditions, the theoretical values of the reaction values are L = 45.4, a = -36.8, and b = 45.0 DPPH radical scavenging activity = 30.9%. When the actual experiment was conducted under these optimal extraction conditions and analyzed, the measured values were L = 46.2, a = -36.1, and b = 48.2, and antioxidant capacity = 31.1% with an average error rate of 2.9%.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.596-601
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• 2006

Because of insufficiency of energy resources and pollution of environment, it is necessary to develop alternative energy sources. Nuclear fission energy is used widely for source of electric Power but being restricted due to radioactivity problem. Nuclear fission is highlighted as the new generation of nuclear energy and researched worldwide because of low risk of radiation effect. The representatives of fusion research is China's EAST, KSTAR of Korea and ITER of world. Korea Superconducting Tokamak Advanced Research(KSTAR) project is on progress for the completion in August, 2007. In this study, the research of utility system for KSTAR be carried out. The utility system of KSTAR is consist of water cooling & heating system, $N_2$ gas system, DI water system, service water system and instrument air & auto control system. The progress of KSTAR utility system is under commissioning state after construction completion. The optimal operation scenario will be verified during commissioning and adopted to the KSTAR operation.