• Journal of Adhesion and Interface
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• v.15 no.3
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• pp.100-108
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• 2014

In this work, a series of molar ratios composed with YD-128 and DDM were chosen based on the viscosity analysis. The mixtures of YD-128 and DDM with the different molar ratios were cured at $170^{\circ}C$ for 15 min followed by post cure at $190^{\circ}C$ for two hours. The thermal properties of the cured samples were investigated with DSC, TGA, DMA, and TMA. The conversion ratio of the mixtures of YD-128 and DDM (1 : 1.1) was calculated by dividing ${\Delta}H$ obtained from DSC experiments for each cured sample by ${\Delta}H$. The TGA data of the cured samples showed that the thermal stability and thermal degradation activation energy were proportional to the amount of DDM in the mixtures. However, the highest tan ${\delta}$, and the lowest thermal expansion data with DMA and TMA respectively were obtained from the stoichiometric mixture of YD-128 and DDM. Furthermore, the different ratio of mixtures were applied to test specimens to be cured at $170^{\circ}C$ to measure single lap shear strength with universal testing machine.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.211-217
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• 2017

The objective of this study is to seek a reliable mixture proportion for magnesium potassium phosphate composite(MKPC) mortars with a near-neutral pH value (below 9.5) and a relatively good compressive strength exceeding 30MPa. The main parameter selected was the molar ratios($M_{mp}$) of $MgO-to-KH_2PO_4$ which varied from 30.4 to 3.4. The setting time of the MKPC mortars tended to shorten with a decrease in $M_{mp}$ value. With regard to the strength development ratio normalized by the 28-day strength, the ranges measured in the mortars with an $M_{mp}$ below 7.9 were 50~61% at 1 day and 60~73% at 3 days, indicating a highly rapid early-strength development. With a decrease in $M_{mp}$, the formation of struvite-K crystal identified as a primary hydration product increased, which led to the decrease of the macro-capillary pores in micro-structures. For achieving the targeted requirements for pH value and compressive strength, the $M_{mp}$ needs to be selected as below 5.1.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.321-330
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• 2011

The physical properties of horticultural substrate are important for optimal plant growth. The physical properties should be properly maintained during the crop growing season for producing higher yield. This experiment was carried out to evaluate the physical properties of different mixtures from various raw materials as horticultural substrates. The mixtures at the different ratios of peatmoss, perlite and vermiculite subjected to 10:0:0, 8:2:0, 6:4:0, 4:6:0, 2:8:0, 0:8:2, 0:10:0, 0:6:4, 0:4:6, 0:2:8, 8:0:2, 0:0:10, 6:0:4, 4:0:6, 2:0:8, 2:6:2, 2:4:4, 4:2:4, 4:4:2, 6:2:2 and 2:2:6 were prepared and analyzed according to two methods of the European Standardization (EN) and Rural Development Administration (RDA). The optimum range of physical properties of a specific horticultural substrate can be predicted using physical-property-triangle. This triangle can also be used to convert a physical property from the EN method to that from the RDA method. Results showed that the mixture at a ratio of > 60% peatmoss, in most cases, is in the range of optimum physical condition for plant growth. We conclude that the developed physical-property-triangle can be suitable to suggest the optimum ratios of horticultural substrates used in this study.

• Journal of Mushroom
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• v.20 no.2
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• pp.61-68
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• 2022

We investigated the standard cultivation substrate for Sparassis latifolia "Neowul" bred in Jeollabuk-do Agricultural Research and Extension Services. Cultivation characteristics and yield were assessed by varying the kind of sawdust and additives, and the mixing ratio. The cultivation period in larch sawdust was the shortest at 97 days. The yield was excellent (143.6 g). The findings indicated that larch is a tree species appropriate for the cultivation of S. latifolia. When the additives were varied, the yield and productivity (53.1%) were highest (116.6 g) for the wheat bran treatment. Thus, wheat bran would be an additive appropriate for culturing S. latifolia. Concerning the use of different mixing ratios, larch sawdust:beet-pulp:wheat bran ratios of 80:15:5 and 85:10:5 resulted in yields of 114.4 g and 111.4 g, and productivity of 52.5% and 51.8%, respectively. These yield and productivity values were not statistically different. Thus, the standard cultivation substrate for S. latifolia can comprise larch sawdust, beet pulp, and wheat bran at a ratio of 80:15:5 or 85:10:5. The carbon/nitrogen (C/N) ratio assumed to be appropriate for the cultivation of S. latifolia was 184-223. Pinheading would be difficult below a C/N substrate ratio of 105. Thus, the C/N ratio of the media, as well as the pH, would be vital factors affecting pinheading during S. latifolia cultivation.

• Clean Technology
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• v.16 no.2
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• pp.132-139
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• 2010

The Cu-Mn mixed oxide catalysts with different molar ratios of Cu/(Cu+Mn) prepared by co-precipitation method have been investigated in CO oxidation at $30^{\circ}C$. The catalysts used in this study were characterized by X-ray Diffraction (XRD), $N_2$ sorption, X-ray photoelectron spectroscopy (XPS), and $H_2$-temperature programmed reduction $(H_2-TPR)$ to correlate with catalytic activities in CO oxidation. The $N_2$ adsorption-desorption isotherms of Cu-Mn mixed oxide catalysts showed a type 4 having pore range of 7-20 nm and BET surface area was increased from 17 to $205\;m^2{\cdot}g^{-1}$ with increasing of Mn content. The XPS analysis showed the surface oxidation state of Cu and Mn represented $Cu^{2+}$and the mixture of $Mn^{3+}$ and $Mn^{4+}$, respectively. Among the catalysts studied here, Cu/(Cu+Mn) = 0.5 catalyst showed the highest activity at $30^{\circ}C$ in CO oxidation and the catalytic activity showed a typical volcano-shape curve with respect to Cu/(Cu+Mn) molar ratios. The water vapor showed a prohibiting effect on the efficiency of the catalyst which is due to the competitive adsorption of carbon monoxide on the active sites of catalyst surface and finally the formation of hydroxyl group with active metals.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.348-355
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• 2023

Biodiesel is known as an environmentally friendly neutral fuel, and a policy of obligatory mixing of a certain ratio is implemented on land. In this study, to verify the feasibility of using biodiesel as a ship fuel, component analysis, metal corrosion test, and storage stability test were performed on the mixing ratios of 0 %, 5 %, 10 %, and 20 % of marine diesel and biodiesel. Component analysis evaluated a total of eight factors including density, kinematic viscosity and flash point according to ISO 8217:2017 standards and the reliability of biodiesel through metal corrosion tests and storage stability tests under atmosphere temperature and harsh conditions (60 ℃) for 180 days. Results demonstrate that component analysis satisfied the ISO 8217:2017 standard in all biodiesel mixing ratios. Furthermore, as the biodiesel mixing ratio increased, the kinematic viscosity, density, and acid value increased and the sulfur content decreased. Metal corrosion rarely occurred in the case of carbon steel, iron, aluminum, and nickel, whereas in the case of copper, corrosion occurred under the influence of oxygen-rich biodiesel under the harsh conditions (60 ℃) of 20 % biodiesel mixture. As for storage stability, discoloration, sludge formation, and fuel separation were not visually confirmed.

• Steel and Composite Structures
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• v.49 no.2
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• pp.245-255
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• 2023

The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to shear-dominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5-23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.

• Journal of Life Science
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• v.19 no.4
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• pp.538-542
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• 2009

In this study, we confirmed water content and oxygen permeability of new polymeric materials synthesized from itaconic acid used for soft contact lenses. In this study, we polymerized materials for soft contact lenses using HEMA (2-hydroxyethyl methacrylate), the based-monomer of soft contact lenses, EGDMA (ethylene glycol dimethacrylate) as a cross linkage agent, and the new additives mono-ester or di-ester derived from itaconic acid commercially produced by the fermentation of A. itaconicus. New polymer materials for contact lenses were synthesized with the mixture of HEMA and mono- or di-ester at different ratios and water content and oxygen permeability (Dk) was analyzed. In polymerizing HEMA and mono-ester (15%), the water content and oxygen permeability of contact lenses were found to be of good value at 57.7% and 28.6 Dk respectively. The mixture of HEMA and mono-ester is more excellent than HEMA/di-ester in regards to water content and oxygen permeability. The water content and oxygen permeability of soft contact lenses made by new polymeric materials were highly represented.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.5
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• pp.436-445
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• 1986

As the second part of the studies on the utilization of polyunsaturated lipids in sardine oil as nutritional or medical supplement, the conditions of lipid extration and concentration, refining, and storage stability of EPA-condensed sardine oil were investigated. In extraction of lipids, solvent ratios of chloroform-methanol mixture(2:1 v/v) affected the final content of unsaturated lipid in extracted oil and recovery. Stepwise solvent fractionation method at various low temperatures was effective to concentrate polyenoic acids like EPA and DHA when acetone or acetone-methanol mixture, added in the ratio of 1:5 (v/v) was applied step by step to different temperatures at 0 to $-35^{\circ}C$. Addition of 1 to $5\%$ (v/v) of water to acetone was also benefit to raise EPA content but that resulted in reducing the yield of condensed oil from $65\%\;to\;28\%$. Concentration rate of polyenoic acids by solvent fractionation in lipid-actone solution (1:5, v/v) at 0 to $-30^{\circ}C$ seemed limited to $5{\sim}8\%$ in fatty acid composition depending on the initial content of those polyenoic acids in the sardine oil. During the extraction, concentration, and alkaline treatment, oxidation was rapidly induced but oxidation products could be thoroughly removed on the process of deceleration and peroxide elimination. To stabilize the reactive polyenoic acid condensed oil during the storage, stuffing nitrogen gas was essential to expel dissolved oxygen in oil or to seal the oil from open air, and the addition of antioxidative agents as BHA and tocopherols were greatly helpful to extend the storage life.

• Composites Research
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• v.17 no.4
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• pp.40-46
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• 2004

A single lap shear test was used to investigate the effects of the ratio of a catalyst to a self-healing agent and curing temperature on the bond performance of autonomic polymer composites. DCPD (dicyclopentadiene), ENB (5-ethylidene-2-norbornene), and their mixture were used as self-healing agents and bis(triclohexylphosphine) benzyllidine ruthenium (IV) dichloride Grubbs' catalyst was used as a catalyst. During the experiments, the catalyst ratios of 1.0wt% and 0.5wt% were applied to DCPD, the catalyst ratio of 0.lwt% was applied to ENB, and the catalyst ratio of 0.5wt% was applied to the mixtutes of DPCD and ENB. In addition, the curing temperatures of $25^{\circ}C$, $60{\circ}C$, and $80^{\circ}C$ were considered. According to the results, the higher catalyst ratio and the longer curing time were required to obtain more stabilized bond shear strength of DCPD. ENB with a lower catalyst ratio was cured faster than DCPD. Unlike DCPD, ENB stabilized after a steady fall from its peak as the curing time increased. Moreover, the mixtures of DCPD and ENB revealed similar curing behavior to ENB, but the increase in mixture ratio of ENB to DCPD caused curing process to be faster. Also the increase in curing temperature caused the bond shear strength to be higher and the curing time to be quicker.