• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.103-108
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• 2022

This research work reports the development of a Ruthenium/2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO)/nitrate catalyst system for the highly selective transformation of isosorbide (1,4:3,6-dianhydro-D-glucitol) to isosorbide-diketone (2,6-dioxabicyclo (3,3,0)octan-4,8-one). Isosorbide is a critical platform molecule for future manufacturing processes. TEMPO has been utilized to convert alcohols to carbonyl compounds for a long time. The optimal chemical reaction condition was found to be when using isosorbide (0.5 mmol) with supported Ru (10 mol%), TEMPO (5 mol%), and sodium nitrate (0.03 mmol) in the presence of acetic acid (3 ml) as a solvent at 50 ℃ and 1 atm oxygen pressure. This catalyst system demonstrated good selectivity (> 97%) and yield (87%) with respect to the desired product, in addition to a putative catalytic double oxidation mechanism.

• Archives of Plastic Surgery
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• v.49 no.5
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• pp.617-632
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• 2022

Tracheoesophageal puncture (TEP) and voice prosthesis insertion following laryngectomy may fail to form an adequate seal. When spontaneous closure of the fistula tract does not occur after conservative measures, surgical closure is required. The purpose of this study was to summarize the available evidence on surgical methods for TEP site closure. A comprehensive search across PubMed, Web of Science, SCOPUS, and Cochrane was performed to identify studies describing surgical techniques, outcomes, and complications for TEP closure. We evaluated the rate of unsuccessful TEP closure after surgical management. A meta-analysis with a random-effect method was performed. Thirty-four studies reporting on 144 patients satisfied inclusion criteria. The overall incidence of an unsuccessful TEP surgical closure was 6% (95% confidence interval [CI] 1-13%). Subgroup analysis showed an unsuccessful TEP closure rate for silicone button of 8% (95% CI < 1-43%), 7% (95% CI < 1-34%) for dermal graft interposition, < 1% (95% CI < 1-37%) for radial forearm free flap, < 1% (95% CI < 1-52%) for ligation of the fistula, 17% (95% CI < 1-64%) for interposition of a deltopectoral flap, 9% (95% CI < 1-28%) for primary closure, and 2% (95% CI < 1-20%) for interposition of a sternocleidomastoid muscle flap. Critical assessment of the reconstructive modality should take into consideration previous history of surgery or radiotherapy. Nonirradiated fields and small defects may benefit from fistula excision and tracheal and esophageal multilayer closure. In cases of previous radiotherapy, local flaps or free tissue transfer yield high successful TEP closure rates. Depending on the defect size, sternocleidomastoid muscle flap or fasciocutaneous free flaps are optimal alternatives.

• Korean Journal of Audiology
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• v.25 no.4
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• pp.209-216
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• 2021

Background and Objectives: We aimed to analyze treatment outcomes following different initial management approaches and confirm treatment regimens for acute low-tone sensorineural hearing loss (ALHL) that would yield the best results. Subjects and Methods: We retrospectively analyzed the medical records of 106 patients with ALHL who visited a university hospital's otology clinic from March 2013 to June 2019. Pure-tone averages at the initial visit and at 2 and 4 weeks after the initial visit were evaluated. Results: Forty-nine patients were enrolled in this study; of them, 41 (83.7%) exhibited complete recovery (CR) at 2 weeks and 43 (87.8%) exhibited CR at 1 month after the initial visit. Regression analysis revealed that CR at 2 weeks after the initial visit was associated with diuretic use [Exp(B): 10.309, 95% confidence interval (CI): 1.007-100]. An initial daily low-dose steroid use was marginally significant [Exp(B): 1.042, 95% CI: 0.997-1.092; p=0.066]. Isolated diuretic use [Exp(B): 25.641, 95% CI: 1.121-90.909; p=0.039] was an independent, good prognostic factor at 1 month after the initial visit. However, other treatment regimens did not affect the final results. Conclusions: A combination of initial daily administration of ≤30 mg prednisolone plus diuretics was sufficient as the first-line treatment for ALHL. High-dose steroids and salvage intratympanic steroid injections can be applied as a second choice; however, the predicted outcome would not be good in that case.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1699-1708
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• 2021

Response surface methodology was applied to determine the optimum extract conditions(extract temperature and time) for the high-quality Agakong beverage. The optimal roasting condition for Agakong was set at 250 ℃ for 30 minutes. As quality criteria of Agakong, pH, color values and isofavone contents with extract temperature and extract time, the probability value (p<0.01) demonstrated a high significance for the regression model. It was found that the higher the extraction temperature and the longer the extraction time, the higher the isoflavones content. The optimized conditions of extraction isoflavones from agakong were found to be optimized ratio of extraction temperature 99.5℃, extraction time 1.7 h and the maximum rutin yield was 10.63 ㎍/mL.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.204-211
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• 2022

In this study, Hollow Concrete Filled FRP Tube Pile(HCFFT Pile) was proposed as a model to utilize the advantages of composite piles and solve the problem of corrosion, which is a disadvantage of CFT piles, and a numerical analysis model was developed to analyze their behavior. The strain compatibility method was applied considering the damage plastic behavior of concrete, the yield plastic behavior of steel, and the elastic behavior of FRP. The flexural strength calculation equation of HCFFT piles was proposed considering the change of the FRP tube section according to the distance from the neutral axis. The flexural strength calculation equation, numerical analysis results, and experimental results were compared and analyzed to verify their adequacy. The results of this study can be used as basic data for the optimal design of various HCFFT piles using FRP.

• ALGAE
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• v.37 no.2
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• pp.105-121
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• 2022

Modern seaweed farming relies heavily on seedlings from natural beds or vegetative cuttings from previous harvests. However, this farming method has some disadvantages, such as physiological variation in the seed stock and decreased genetic variability, which reduces the growth rate, carrageenan yield, and gel strength of the seaweeds. A new method of seedling production that is sustainable, scalable, and produces a large number of high-quality plantlets is needed to support the seaweed farming industry. Recent use of tissue culture and micropropagation techniques in eucheumatoid seaweed production has yielded promising results in increasing seed supply and growing uniform seedlings in large numbers in a shorter time. Several seaweed species have been successfully cultured and regenerated into new plantlets in laboratories using direct regeneration, callus culture, and protoplast culture. The use of biostimulants and plant growth regulators in culture media increases the seedling quality even further. Seedlings produced by micropropagation grew faster and had better biochemical properties than conventionally cultivated seedlings. Before being transferred to a land-based grow-out system or ocean nets for farming, tissue-cultured seedlings were recommended to undergo an acclimatization process to increase their survival rate. Regular monitoring is needed to prevent disease and pest infestations and grazing by herbivorous fish and turtles during the farming process. The current review discusses recent techniques for producing eucheumatoid and other valuable seaweed farming materials, emphasizing the efficiency of micropropagation and the transition from laboratory culture to cultivation in land-based or open-sea grow-out systems to elucidate optimal conditions for sustainable seaweed production.

• Clean Technology
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• v.15 no.2
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• pp.130-136
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• 2009

Commercial catalyst (Cu-Zn/$Al_2O_3$, Johnson Matthey Co., 83-3 Catalyst) was applied to the hydrogen production by steam reforming of methanol in the micro-channel reactor (MCR). The steam reforming of methanol was tested over Cu-Zn catalyst at temperatures in the range of 200 and 300$^{\circ}C$, the catalyst size of 0.05${\sim}$2.2 mm, the space velocity of 3,000${\sim}$10,000 $hr^{-1}$ in a fixed bed continuous flow reactor. The conversion of methanol and the yield $H_2$ preferred high temperatures and low space velocities, and had optimal results with the particle size of 0.35 mm. Based on the results from experiments with fixed bed reactor, two types of MCR, boat bed and stacked bed MCRs, were studied. The stacked bed type MCR showed better methanol conversion compared with the boat type one.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.16-23
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• 2023

The objective of this numerical study is to investigate the effect of the shape and material of the blower blade for the electrified speed sprayer on the blowing performance. The shape of the blade was changed to the bonding angle, the number of blades, the width of the blade, and the blade length based on the existing model. In order to obtain the reliability of the numerical model, the analysis of the grid dependence was performed in the numerical analysis. The numerical analysis results were compared and analyzed in terms of the agricultural chemical penetration length characteristics, flow uniformity characteristics, and velocity distribution characteristics. Furthermore, the effect of material change on weight reduction and structural characteristics was also compared and analyzed. As a result of the analysis, it was found that the optimal condition was that the blade angle was 45°, the number of blades was 12, and the width was 115 mm, which was confirmed through a comparison of the inlet mass flow rate. As a result of the equivalent stress lower than the yield strength due to the material change from aluminum to steel compared to the existing steel, structural defects do not appear, and it is judged that the operation time compared to the battery capacity will be improved through the weight reduction of the blade.

• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.216-225
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• 1995

Simulation for a dynamic analysis of the electrolytic preparation of U(IV) in two-phases system, which consisted of mass transfer of U(VI) from TBP phase into HNO$_3$ solution and electrolytic re-duction of U(VI) to U(IV) at a cathode in aqueous phase, was carried out in order to establish the most suitable operating condition and best electrode area as basic design data for the system. It was found that maintaining an appropriate mass transfer rate was more significant rather than enlarging the surface area of the cathode for more effective production yield of U(IV). The electrode area and the operation time affected deeply the production composition of U(IV) in the resulting aqueous phase. And optimal electrode areas ore evaluated to meet production criteria of U(IV) of resulting solution in several system conditions. Though about 0.37M HNO$_3$ was preferable to prepare the solution of U(IV), nitric acid concentration should be higher than 0.5M to prevent a hydrolysis of U(IV) in the aqueous phase.

• Journal of Korean Medicine for Obesity Research
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• v.23 no.1
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• pp.10-17
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• 2023

Objectives: The aim of this study was to compare the total phenolic content of Korean Acanthopanax senticosus stems harvested in different seasons and provide basic data for developing functional reinforcement products based on the optimal harvesting time. Methods: Each sample harvested in different seasons was extracted and concentrated twice for 2 hours using 70% ethyl alcohol. Phenolic compounds were analyzed using high-performance liquid chromatography for simultaneous multi-component analysis of 14 compounds, including syringaresinol and so on. Results: The results showed that the stem of Korean Acanthopanax senticosus harvested in winter (November 29th) (EAS-5) had the highest phenolic content of 1.038%. The stem of Korean Acanthopanax senticosus harvested in autumn (October 1st) (EAS-4) showed the second-highest phenolic content of 0.764%, followed by the stem of Korean Acanthopanax senticosus harvested in spring (February 2nd) (EAS-1) with a content of 0.390%. On the other hand, the stem of Korean Acanthopanax senticosus harvested in the summer (June 2nd) (EAS-3) showed the lowest content at 0.342%. In conclusion, the stem of Korean Acanthopanax senticosus harvested in winter (EAS-5) showed the highest phenolic compound content. Conclusions: Considering the extraction yield and the total phenolic content, as well as the concentrations of key functional components such as eleutheroside B, chlorogenic acid, and syringaresinol in the 70% ethyl alcohol extract of Korean Acanthopanax senticosus, it is suggested that the stems of Korean Acanthopanax senticosus harvested during the winter season are suitable for the development of novel materials with enhanced anti-obesity functionality.