• Journal of agriculture & life science
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• v.46 no.2
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• pp.139-149
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• 2012

Black garlic and Gaeddongssuk (Artemisia annua L.) were extracted using central composite design by response surface methodology (RSM) in 11 conditions (A~K) with $110{\sim}130^{\circ}C$ and 2~4 hr, and then each extracts were monitored for the total phenol, flavonoid contents and antioxidant activities. The optimum extraction conditions for black garlic and Gaeddongssuk are selected 3 conditions ($130^{\circ}C$, 4 hr; $120^{\circ}C$, 3 hr; $130^{\circ}C$, 3 hr) and 1 condition ($120^{\circ}C$, 3 hr), respectively. They were mixed according to the following ratio; 1:0.5, 1:1, 1:1.5 and 1:2 (black garlic: Gaeddongssuk extract, w/w), and then these composites were tested to the total phenol, flavonoid contents and antioxidant activities. Antioxidant activities of black garlic and Gaeddongssuk extracts by $120^{\circ}C$, 3 hr condition were higher. And the optimal mixture ratio of black garlic and Gaeddongssuk was 1:1.5 (w/w).

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.191-199
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• 2021

A distillation column, which is a main facility of the chemical process, separates the desired product from a mixture by using the difference of boiling points. The distillation process requires the optimization and the prediction of operation because it consumes much energy. The target process of this study is difficult to operate efficiently because the composition of feed flow is not steady according to the supplier. To deal with this problem, we could develop a data-driven model to predict operating conditions. However, data preprocessing is essential to improve the predictive performance of the model because the raw data contains outlier and noise. In this study, after optimizing the predictive model based long-short term memory (LSTM) and Random forest (RF), we used a low-pass filter and one-class support vector machine for data preprocessing and compared predictive performance according to the method and range of the preprocessing. The performance of the predictive model and the effect of the preprocessing is compared by using R2 and RMSE. In the case of LSTM, R2 increased from 0.791 to 0.977 by 23.5%, and RMSE decreased from 0.132 to 0.029 by 78.0%. In the case of RF, R2 increased from 0.767 to 0.938 by 22.3%, and RMSE decreased from 0.140 to 0.050 by 64.3%.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.99-106
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• 2021

To circumvent the skin problem from phenylethanol (PhE), we have studied on the enzymatic synthesis of phenylethanol galactoside (PhE-gal) as an alternative to PhE. Base on the previous study, we optimized the reaction conditions for PhE-gal synthesis from PhE using E. coli β-galactosidase (β-gal). The optimal amount of β-gal, PhE concentration, pH, and temperature for PhE-gal synthesis were 0.45 U/ml, 1%, 8.0, 40℃, respectively. Under these conditions, about 81.9 mM PhE was converted into about 47.4 mM PhE-gal, in which the conversion yield was about 57.9%. Meanwhile, when the reaction mixture containing PhE and PhE-gal was mixed and fractionated with water-immiscible solvent (EA or MC), it was observed that PhE-gal was distributed in water phase, and PhE was distributed in solvent phase. Additionally, PhE-gal was clearly distributed into water phase when MC was used, but PE-gal was not when EA was used. In the future, we are planning to carried out the continuing study on developing an alternative cosmetic preservative using PhE-gal.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.2
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• pp.54-60
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• 2023

In this study, microstructure and basic property analysis of DG (Desulfurization gypsum) and CCMs (Carbondioxide conversion capture materials) made by reacting CO₂ with DG were conducted to analyze applicability as a cement admixture. The main crystalline phases of DG were CaO and CaSO₄, and CCMs were CaSO₄, CaCO₃, Ca(OH)₂ and CaSO₄·H₂O. As a result of particle size analysis, the difference in average particle sizes between the two materials was about 7 ㎛. No major heavy metals were detected in the CCMs, and as a result o f TGA, the CO₂ decomposition of CCMs was more than twice as high as that of DG. Therefore, it was judged that CCMs could be used as a cement admixture through optimization of manufacturing conditions. As a results of measuring the strength behavior of DG and CCMs mixture ratios, the long-term strength of CCMs-mixed mortar was higher, and this is due to the filler effect of CaCO₃ in CCMs.

• Food Science and Preservation
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• v.24 no.7
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• pp.957-964
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• 2017

The purpose of this study was to determine the optimum spray drying conditions of soft persimmon latte using response surface methodology that is a statistical procedure used for optimization studies. A central composite design was applied to investigate the effects of independent variables, inlet temperature ($X_1$), air flow rate ($X_2$), and feed flow rate ($X_3$), on responses such as yield, water absorption index, and total phenolic compounds. Statistical analysis revealed that independent variables significantly affected all the responses. A maximum yield of 8.11 g was obtained at $90^{\circ}C$ of $X_1$, 51.82 mL/min of $X_2$ and 7.00 mL/min of $X_3$. A minimum water absorption index of 0.58 was obtained at $101^{\circ}C$ of $X_1$, 60.00 mL/min of $X_2$ and 17.00 mL/min of $X_3$. A maximum total phenolic compounds of $298.02{\mu}g/mL$ was obtained at $90^{\circ}C$ of $X_1$, 43.33 mL/min of $X_2$ and 17.00 mL/min of $X_3$. In conclusion, the best spray drying conditions were as follows: $X_1$, $90^{\circ}C$; $X_2$, 53 mL/min; $X_3$, 17 mL/min. Under those optimal conditions, the powder's yield (7.46 g), water absorption index (0.54), and the content of total phenolic compounds ($294.75{\mu}g/mL$) were estimated.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.33-39
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• 2001

To develop a method for separation process using Sep-pak $C_18$, simultaneous and systematic analysis of 8 permitted and 11 non-permitted synthetic food colors in Korea, optimization of analysis conditions for reverse phase ion-pair high performance liquid chromatography was carried out. For the best result of Sep-pak $C_18$ separation the pH of color standard mixture solution was $5{\sim}6$ and 0.1% HCl-methanol solution were set as eluent. The colors eluated from Sep-pak $C_18$ cartridge were determined and confirmed by high performance liquid chromatography with a photodiode array detector at 420 nm for yellow colors type, at 520 nm for red colors type, at 600 nm for blue and green colors type and at 254 nm for mixed colors. Conditions for HPLC analysis were as follows: column, Symmetry $C_18$ (5 m, 3.9 mm $i.d.{\times}150\;mm$); mobile phase, 0.025 M ammonium acetate (containing 0.01 M tetrabutylammonium bromide) : acetonitrile : methanol (65 : 25 : 10) and 0.025 M ammonium acetate(containing 0.01 M tetrabutylammonium bromide) : acetonitrile : methanol (40 : 50 : 10); flow rate, 1 mL/min. It takes 35 minutes for simultaneaus analysis and 18 minutes for systematic analysis. The detection limits range of each colors were $0.01{\sim}0.05\;{\mu}g/g$.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.12
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• pp.605-619
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• 2014

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

• Clean Technology
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• v.28 no.3
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• pp.218-226
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• 2022

As a result of the recent social transformation towards a hydrogen economy and carbon-neutrality, the demands for hydrogen energy have been increasing rapidly worldwide. As such, eco-friendly hydrogen production technologies that do not produce carbon dioxide (CO₂) emissions are being focused on. Among them, ammonia (NH₃) is an economical hydrogen carrier that can easily produce hydrogen (H₂). In this study, Ru/Al₂O₃ catalyst coated onmetallic monolith for hydrogen production from ammonia was prepared by a dip-coating method using a catalyst slurry mixture composed of Ru/Al₂O₃ catalyst, inorganic binder (alumina sol) and organic binder (methyl cellulose). At the optimized 1:1:0.1 weight ratio of catalyst/inorganic binder/organic binder, the amount of catalyst coated on the metallic monolith after one cycle coating was about 61.6 g L^-1. The uniform thickness (about 42 ㎛) and crystal structure of the catalyst coated on the metallic monolith surface were confirmed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Also, a numerical optimization regression equation for NH3 conversion according to the independent variables of reaction temperature (400-600 ℃) and gas hourly space velocity (1,000-5,000 h^-1) was calculated by response surface methodology (RSM). This model indicated a determination coefficient (R²) of 0.991 and had statistically significant predictors. This regression model could contribute to the commercial process design of hydrogen production by ammonia decomposition.

• Microbiology and Biotechnology Letters
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• v.36 no.1
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• pp.61-66
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• 2008

The proteins in whey are separated and used as food additives. The remains (mainly lactose) are spray-dried to produce sweet whey powder, which is widely used as an additive for animal feed. Sweet whey powder is also used as a carbon source for the production of valuable products such as polysaccharides. Glucose, fructose, galactose, and sucrose as asupplemental carbon source were evaluated for the production of PS-7 from Azotobacter indicus var. myxogenes L3 grown on whey based MSM media. Productions of PS-7 with 2% (w/v) fructose and sucrose were 2.05 and 2.31g/L, respectively. The highest production of PS-7 was 2.82g/L when 2% (w/v) glucose was used as the carbon source. Galactose showed low production of PS-7 among the carbon sources tested. The effects of various carbon sources addition to whey based MSM medium showed that glucose could be the best candidate for the enhancement of PS-7 production using whey based MSM medium. To evaluate the effect of glucose addition to whey based media on PS-7 production, fermentations with whey and glucose mixture (whey 1, 2, 3%; whey 1% + glucose 1%, whey 1% + glucose 2% and glucose 2%, w/v) were carried out. Significant enhancement of PS-7 production with addition of 1% (w/v) and 2% (w/v) glucose in 1% (w/v) whey media was observed. The PS-7 concentration of 2% glucose added whey lactose based medium was higher than that of 1% glucose addition, however, the product yield $Y_{p/s}$ was higher in 1% glucose added whey lactose based MSM medium. Therefore, the optimal condition for the PS-7 production from the Azotobacter indicus var.myxogenes L3, was 1% glucose addition to 1% whey lactose MSM medium.

• Culinary science and hospitality research
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• v.16 no.4
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• pp.286-296
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• 2010

The purpose of this study is to develop fresh pasta added with mulberry leaf powder as functional fresh pasta. Through previous research, the mixture of 40% of flour and 60% of rice powder was optimum for making noodles with mulberry leaf powder. Making fresh pasta with 40% of wheat flour, 60% of rice powder (optimum moo for making noodles) and mulberry leaf powder(0.5% 1.0% 1.5% 2.0%) was done, followed by the mechanical test(moisture content, color value, texture, tension) and the sensory analysis(quantitative descriptive analysis, preference test). Moisture contents of raw pasta and cooked pasta were the highest in control; scores for moisture contents of cooked pasta were higher than those of raw pasta. The result indicated that the more mulberry leaf powder was, the lower L-value and a-value were in raw pasta and cooked pasta. While the b-vale(yellowness) of raw pasta was the highest in control(9.81), 1.0% of mulberry powder addition sample was the highest in cooked pasta. For hardness, the 2.0% of mulberry leaf powder addition sample has high scores, and adhesiveness and chewiness were no significant difference. The 0.5% of mulberry leaf powder addition sample was the longest in tension distance, which was resulted from the lack of water contents in mulberry leaf powder. In cooked pasta, tension distance had no significant difference between the samples, and force showed the highest score in control. The quantitative descriptive analysis showed that color intensity, savory taste, bitterness were the highest in the 2.0% of mulberry leaf powder addition sample. Gloss and chewiness were no significant difference between the samples. Grassy flavor, savory flavor, bitterness and grainess were intense as mulberry leaf powder was added The preference test showed that MRP 1.5 containing 1.5% of mulberry leaf powder was the most preferable for color, texture and overall quality. In conclusion, 40% of wheat flour, 60% of rice powder and 1.5% of mulberry leaf powder made the best formula of fresh pasta with mulberry leaves.