• Transactions of the Korean hydrogen and new energy society
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• v.17 no.1
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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.

• Geomechanics and Engineering
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• v.16 no.1
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• pp.105-112
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• 2018

This paper presents results of a compressive investigation conducted on weathered soil stabilized with ground bottom ash (GBA) and red mud (RM). The effects of water/binder ratio, RM/GBA ratio, chemical activator (NaOH and $Na_2SiO_3$) and curing time on unconfined compressive strength of stabilized soils were examined. The results show that the water/binder ratio of 1.2 is optimum ratio at which the stabilized soils have the maximum compressive strength. For 28 days of curing, the compressive strength of soils stabilized with alkali-activated GBA and RM varies between 1.5 MPa and 4.1 MPa. The addition of GBA, RM and chemical activators enhanced strength development and the rate of strength improvement was more significant at the later age than at the early age. The potential environmental impacts of stabilized soils were also assessed. The chemical property changes of leachate from stabilized soils were analyzed in terms of pH and concentrations of hazardous elements. The observation revealed that the soil mixture with ground bottom ash and red mud proved environmentally safe.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.225-232
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• 2003

With an aim placed on its exploitation on practical injector design, liquid phase mixing due to unlike split triplet impinging element is experimentally investigated by a series of cold tests. Non-reacting kerosene/water spray simulates the kerosene/LOX propellant combination. Measurements of local mixture ratio distribution were made for different injection configurations and different momentum ratios. Mixing and mixing controlled characteristic velocity efficiencies are measured in terms of oxidizer/fuel jet momentum ratio from 0.5 to 8. Extent of mixing and its influence on hot performance are estimated in terms of mixing efficiency and mixing controlled characteristic velocity. Envelope of design locus for optimum mixing quality and corresponding maximum hot performance are proposed. Effects of momentum ratio, orifice diameter ratio and jet velocity ratios are also presented and discussed.

• International Journal of Highway Engineering
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• v.20 no.1
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• pp.47-58
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• 2018

PURPOSES : The purpose of this study is to evaluate the mechanical properties of a cold-recycling asphalt mixture used as a base layer and to determine the optimum emulsified-asphalt content for ensuring the mixture's performance. METHODS : The physical properties (storage stability, mixability, and workability) of three types of asphalt emulsion (CMS-1h, CSS-1h, and CSS-1hp) were evaluated using the rotational viscosity test. Asphalt emulsion residues, prepared according to the ASTM D 7497-09 standard, were evaluated for their rheological properties, including the $G*/sin{\delta}$and the dynamic shear modulus (${\mid}G*{\mid}$). In addition, the Marshall stability, indirect tensile strength, and tensile-strength ratio (TSR) were evaluated for the cold-recycling asphalt mixtures fabricated according to the type and contents of the emulsified asphalt. RESULTS : The CSS-1hp was found to be superior to the other two types in terms of storage stability, mixability, and workability, and its $G*/sin{\delta}$ value at high temperatures was higher than that of the other two types. From the dynamic shear modulus test, the CSS-1hp was also found to be superior to the other two types, with respect to low-temperature cracking and rutting resistance. The mixture test indicated that the indirect tensile strength and TSR increased with the increasing emulsified-asphalt content. However, the mixtures with one-percent emulsified-asphalt content did not meet the national specification in terms of the aggregate coverage (over 50%) and the indirect tensile strength (more than 0.4 MPa). CONCLUSIONS : The emulsified-asphalt performance varied greatly, depending on the type of base material and modifying additives; therefore, it is considered that this will have a great effect on the performance of the cold-recycling asphalt pavement. As the emulsified-asphalt content increased, the strength change was significant. Therefore, it is desirable to apply the strength properties as a factor for determining the optimum emulsified-asphalt content in the mix design. The 1% emulsified-asphalt content did not satisfy the strength and aggregate coverage criteria suggested by national standards. Therefore, the minimum emulsified-asphalt content should be specified to secure the performance.

• Journal of the Korea Organic Resources Recycling Association
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• v.30 no.4
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• pp.27-40
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• 2022

In this study, the anaerobic digestion potential and thermo-chemical pre-treatment were evaluated for efficient anaerobic co-digestion of dewatered sludge(DS) and food waste(FW). As a result, the degradable organic matter concentration and methane yield of FW were evaluated to 2.2 and 1.3 times higher than that of DS, respectively. In order to increase the amount of biogas production, it was determined that it is desirable to increase the mixing ratio of FW. The efficiency of thermo-chemical pre-treatment was evaluated for the reaction temperature, NaOH concentration, reaction time and mixture ratio. As a result of evaluation through pre-treatment efficiency and dehydration capacity, the optimum pre-treatment conditions were evaluated as follows: reaction temperature 140℃, NaOH concentration 60 meq/L, reaction time 60 min, mixture ratio 1:5(DS:FW). The gas production rate and methane yield increased 1.6 and 1.5 times, respectively, compared to before and after applying the optimum pre-treatment. Therefore, it is necessary to increase the mixing ratio of food waste for efficient anaerobic co-digestion of DS and FW. and it is necessary to increase the solubilization efficiency of waste by application of pre-treatment.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.823-828
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• 2011

Characteristics of water separation in a FWKO(Free Water Knok Out) vessel was investigated to remove water from oil-water mixture. Decane, toluene, and asphalt were used as model oils. Preliminary experiments were carried out for decane in a prototype FWKO vessel. Based on the results of preliminary experiments, the prototype vessel was modified and its performance was evaluated by using toluene. The effects of experimental variables on the separation of oil-water mixture were evaluated in terms of separation efficiency. The experimental variables include water cut(water ratio), number of baffles, residence times, and operation temperatures. The optimum conditions of water separation were found to be 0.8 water cut, 3 baffles, 1,200 sec, and $45^{\circ}C$.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.29-37
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• 2013

In order to recycle both water sludge and waste fishing net(WFN), it was investigated in this paper the engineering characteristics of mixtures that consisted of different content of water sludge(0%, 10%, 30%, 50%) and reinforced with waste fishing net(unreinforced, untreated WFN, glue treated WFN). WFN or glue treated WFN(1&2 layers) was also added to the mixture to improve the interlocking between the soil particle and WFN. Several series of laboratory tests such as compaction test, triaxial test, oedometer test, permeability test and leaching test were carried out. The experimental test results indicated that, as water sludge content increases, maximum dry unit weight, cohesion, friction angle, and permeability of the mixture decrease, while optimum moisture content, compression index, expansion index and compressibility increase. For the case of reinforced mixture, its cohesion and friction angle are increased due to the inclusion of WFN and glue treated WFN. Leaching result of mixture was satisfied with standard of ministry of environment.

• The Korean Journal of Food And Nutrition
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• v.29 no.6
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• pp.1040-1049
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• 2016

In this study, we aimed to develop a mixed tea prepared with roasted mulberry leaf and fruit using response surface methodology (RSM). Roasting of mulberry leaf was by 6 stages, as shown in Fig. 1; and mulberry fruit was roasted in 4 stages, as shown in Fig. 2. Subsequently, physicochemical measurements such as total polyphenol content, nitric oxide production content, and ${\alpha}$-glucosidase inhibitory effect were obtained for each sample. Central composite design was applied to prepare samples containing varying contents of roasted mulberry leaf (RoML) and roasted mulberry fruit (RoMF); subsequently, sensory evaluation was conducted. The total polyphenol content of roasted samples (RoML and RoMF) were significantly higher than that of raw samples (RaML and RaMF), respectively. The nitric oxide (NO) production of roasted samples were significantly lower than that of control (LPS induced RAW 264.7 cell). The ${\alpha}$-glucosidase inhibitory effect of roasted samples was significantly higher than that of raw samples, respectively. Based on the RSM estimation for determination of optimum ratio by sensory evaluation (taste, color, and flavor) among 13 mixed samples, the optimum mixing ratio of RoML and RoMF for taste, color, and flavor were 1.64 g (RoML) and 0.88 g (RoMF), 1.35 g (RoML) and 0.92 g (RoMF), 1.65 g (RoML) 1.03 g (RoMF), respectively. Based on results of three sensory evaluations, mixing ratio comprising 1.54 g of RoML and 0.92 g of RoMF is desirable for delicious tea with functionality.

• Food Engineering Progress
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• v.14 no.2
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• pp.112-117
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• 2010

Black ginger, obtained from steaming and drying process, provides the various functional properties. This study was performed to investigate the optimum processing conditions for black ginger with high content of biologically active substance such as anti-oxidations. Optimum processing conditions such as temperature and time for black ginger was determined by response surface methodology (RSM) with manufacturing process and functionality. The optimum steaming condition was determined 6 hours at 93.2$^{\circ}C$, and 82.7 mg/L DPPH scavenging activities was obtained at this condition. The black ginger drink was made with black ginger extracts, Japanese apricot, and honey. Interaction effects of these ingredients were investigated by modified distance based on design and analyzed by linear, nonlinear regression model, and RSM. The optimization of mixture ratio was made by statistical modeling using DPPH scavenging activities and sensory properties which are the important target constraints in drink. Total flavonoids showed a linear canonical form, while preference and antiradical activity showed a nonlinear canonical form indicating the higher interaction among mixtures. The response trace plot revealed that antiradical activity, sensory properties and total flavonoids were quite sensitive to the drink blending. The optimum formulation of the drink was set at 14.2% of black ginger extracts, 5% of Japanese apricot, and 10.8% honey.

• Korean Journal of Plant Resources
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• v.12 no.3
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• pp.171-178
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• 1999

The purpose of this study was to investigate the optimal mixture ratio for the mycelial culture of the Pleurotus ostreatus. The chief cultural media in this study were cotton hull, sawdust and rice straw and the supplemental media were zeolite, corn cob, defatted rice bran, white cotton, tobacco trash powder, rice hull and peat. The results of this study were as follows; the optimal mixture ratio of the chief cultural media were effective in 6 : 3 : 1(V/V, %), and the mycelial growth and density in the supplemental media were considerably better 1% zeolite,3% corn cob, 5% defatted rice bran, 1% white cotton, 1% tobacco trash powder, 7% rice hull in good order. The optimal mixture ratio be to the mixed supplemental media in the chief cultural media were as follows ; 2 : 2(V/V, %) at the conditions of mixed zeolite and corn cob; 3 : 2(V/V, %) at the conditions of mixed defatted rice bran and white cotton; 1 : 3(V/V, %) at the conditions of mixed tobacco trash powder and rice hull. At the conditions of the whole cultural media mixed, the mycelial growth and density were in good conditions ; cotton hull, sawdust, rice straw, zeolite, corn cob, defatted rice bran, white cotton, tobacco trash powder, rice hull, and peat were mixed 43.0 : 17.2 : 25.8 : 2.0 : 2.0 : 3.0 : 2.0 : 1.0 : 3.0 : 1.0 (V/V, %).