• Journal of the Korean Chemical Society
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• v.65 no.4
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• pp.254-259
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• 2021

The purpose of this work is the development of a method for an effective, less expensive, rapid, and simultaneous determination of three phenolic compounds (caffeic acid, gallic acid, and quercetin) widely present in food resources and known for their antioxidant powers. The method relies on partial least squares (PLS) calibration of UV-visible spectroscopic data. This model was applied to simultaneously determine, the concentrations of caffeic acid (CA), gallic acid (GA), and quercetin (Q) in six herb infusion extracts: basil, chive, laurel, mint, parsley, and thyme. A wavelength range (250-400) nm, and an experimental calibration matrix with 21 samples of ternary mixtures composed of CA (6.0-21.0 mg/L), GA (10.0-35.2 mg/L), and Q (6.4-17.5 mg/L) were chosen. Spectroscopic data were mean-centered before calibration. Two latent variables were determined using the contiguous block cross-validation procedure after calculating the root mean square error cross-validation RMSECV. Other statistic parameters: RMSEP, R², and Recovery (%) were used to determine the predictive ability of the model. The results obtained demonstrated that UV-visible spectrometry and PLS regression were successfully applied to simultaneously quantify the three phenolic compounds in synthetic ternary mixtures. Moreover, the concentrations of CA, GA and Q in herb infusion extracts were easily predicted and found to be 3.918-18.055, 9.014-23.825, and 9.040-13.350 mg/g of dry sample, respectively.

• Korean Journal of Environmental Agriculture
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• v.35 no.4
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• pp.241-246
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• 2016

BACKGROUND: Recently, the widespread distribution of pesticides in the hive has been of concern about pesticide exposure on honeybee (Apis mellifera L.) health. Larval toxicity was adapted to assess the synergistic and antagonistic interaction of cumulative mortality to the honeybee larvae of the four most common pesticides detected in pollen. METHODS AND RESULTS: Acetamiprid($3.0{\mu}l/L$), chlorothalonil ($803.0{\mu}l/L$), coumaphos ($128.0{\mu}l/L$), and tau-fluvalinate ($123.0{\mu}l/L$) were tested in combination; binary, ternary and four component mixture. Larvae were exposed to four pesticides mixed in diet at the average levels detected in pollen. As a result, synthetic toxicity was observed in the binary mixture of acetamiprid with coumaphos. The binary and ternary component mixtures of tested pesticides have mostly demonstrated additive effect in larval bees. The significant antagonistic effects were found in four parings of mixtures including chlorothalonil added to acetamiprid/tau-fluvalinate or acetamiprid/coumaphos/tau-fluvalinate, and tau-fluvalinate added to acetamiprid/chlorothalonil or acetamiprid/coumaphos/chlorothalonil. CONCLUSION: Interactions between combinations of four pesticides showed mostly additive or antagonistic effects in larval bees. Therefore, predicting the larval mortality of pesticides mixtures on the basis of the results of single pesticide may actually overestimate the risk. We suggest that pesticide mixture in pollen be evaluated by adding their toxicity together for complete data on interactions.

• Clean Technology
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• v.13 no.1 s.36
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• pp.34-45
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• 2007

Phase behavior of the ternary systems of water-insoluble simvastatin drug, which is well known to be effective drugs for hypercholesterolemia therapy, in solvent mixtures of dichloromethane and supercritical carbon dioxide was investigated to present a guideline of establishing operating conditions in the particle formation of the drugs by a supercritical anti-solvent recrystallization process utilizing dichloromethane as a solvent and carbon dioxide as an anti-solvent. The solubilities of simvastatin in the mixtures of dichloromethane and carbon dioxide were determined as functions of temperature, pressure and solvent composition by measuring the cloud points of the ternary mixtures at various conditions using a high-pressure phase equilibrium apparatus equipped with a variable-volume view cell. The solubility of the drug increased as the dichloromethane composition in solution and the system pressure increases at a fixed temperature. A lower solubility of the drug was obtained at a higher temperature. The second half of this work is focused on the particle formation of the simvastatin drug by a supercritical anti-solvent recrystallization process in a cylindrical high-pressure vessel equipped with an impeller. Microparticles of the simvastatin drug were prepared as functions of pressure (8 MPa to 12 MPa), temperature (303.15 K, 313,15 K), feed flow rate of carbon dioxide, and stirring speed (up to 3000 rpm), in order to observe the effect of those process parameters on the size and shape of the drug microparticles recrystallized.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.8 no.3
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• pp.423-436
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• 1996

Thermodynamic performance of eight zeotropic R-22 alternative refrigerant mixtures selected by AREP(R-22 Alternative Refrigerants Evaluation Program) and R-32/R-125/R-134a(23%/25%/52%), namely R-407C were evaluated by the "drop-in" simulation method. An existing air conditioner was selected and its design data were used for the simulation. "ARI Test A" air conditions were applied. The degree of vapor superheat at the compressor inlet fixed at $5^{\circ}C$ for all the mixtures. The results of the simulation were compared with those of R-22. COPs of all mixtures except for R-32/R-227ea(35%/65%) and R-32/R-125/R-134a(10%/70%/20%), were higher than that of R-22 by 2%~8%, while the capacities were all lower than that of R-22 by 13%~27%. COP of R-32/R-134a(40%/60%) was 2.4% higher but the capacity was 15% lower than those of R-22. In the case of R-32/R-134a(30%/70%), COP and capacity were 5.5% higher and 15% lower than those of R-22, respectively. Among the ternary mixtures, R-407C and R-32/R-125/R-134a(30%/10%/60%) showed the best performance. COP of R-407C was 2.4% higher than those of R-22 but the capacity was 15% lower.

• Steel and Composite Structures
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• v.23 no.5
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• pp.543-555
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• 2017

The mechanical properties of steel fiber reinforced high strength concrete (SFRHSC) made with binary and ternary blends of metakaolin (MK) and ground pumice (GP) are investigated in this study. The investigated properties are ultrasonic pulse velocity ($U_{pv}$), compressive strength ($f_c$), flexural strength ($f_f$) and splitting tensile strength ($f_{st}$) of SFRHSC. A total of 16 steel fiber reinforced concrete mixtures were produced by a total binder content of $500kg/m^3$ for determining the effects of MK and GP on the mechanical properties. The design $f_c$ was acquired from 70 to 100 MPa by using a low water-binder ratio of 0.2. The test results exhibit that high strength concrete can be obtained by replacing the cement with MK and GP. Besides, correlations between these results are executed for comprehending the relationship between mechanical properties of SFRHSC and the strong correlations are observed between these properties. Moreover, two models in the gene expression programming (GEP) for predicting the $f_c$ of SFRHSC made with binary and ternary blends of MK and GP have been developed. The results obtained from these models are compared with the experimental results. These comparisons proved that the results of equations obtained from these models seem to agree with the experimental results.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.1
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• pp.55-66
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• 1996

This study was conducted to evaluate breakthrough characteristics of respirator cartridge using multi-organic vapors, including carbon tetrachloride, trichloroethylene, and toluene. The organic vapors were used as single phase, binary system, and ternary system. The results are summarized as follows. 1. Organic vapors studied were 1,000 ppm, 750 ppm, 500 ppm and 250 ppm in single phase. Carbon tetrachloride having the highest molecular weight showed the breakthrough first, and breakthrough sequency by organic vapor was dependent on its molecular weight. The 10% breakthrough times at 1,000 ppm of organic vapor were 97 minutes for carbon tetrachloride, 129 minutes for trichloroethylene and 135 minutes for toluene. 2. When concentrations of organic vapors were at levels of the Threshold Limit Values, the lives of the respirator cartridges were 122 hours in carbon tetrachloride, 18 hours in trichloroethylene and 28 hours in toluene. 3. In the binary system at a total concentration of 1,000 ppm with carbon tetrachloride and trichloroethylene, breakthrough times ranged from 104 minutes to 125 minutes, which were longer than 97 minutes in a single phase (1,000 ppm) for carbon tetrachloride, but shorter than breakthrough times for TCE and Toluene. 4. Breakthrough times in the binary system with carbon tetrachloride and toluene were 131~132 minutes. 5. Breakthrough times in the ternary system with carbon tetrachloride, toluene, and trichloroethyl ene were $120{\pm}8$ minutes, which were longer than 97 minutes in the single phase (1,000 ppm) for carbon tetrachloride, equal to 129 minutes for trichloroethylene, and shorter than 135 minutes for toluene. Those were almost similar to $124{\pm}9$ minutes of breakthrough times in the binary systems.

• Fire Science and Engineering
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• v.15 no.3
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• pp.14-20
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• 2001

The flash points are one of the most important fundamental properties used to determine the potential for fire and explosion hazards of flammable substances. A classification of the flash points is important for the safe handling of flammable liquids which constitute the solvent mixtures. Basic to all flash points behavior are vapor pressure and explosive limits(lower explosive limit and upper explosive limit). The flash points of flammable solvent mixtures can be calculated with the appropriate use of the fundamental laws of Raoult, Dalton, Le Chatelier and activity coefficient models. In this study, the reference values of lower flash points were compared with the calculated values by using Raoult's law and MRSM(modified response surface methodology) model. The lower flash points were in agreement with the predicted by Raoult's law and MRSM model. By means of this methodology, it is possible to evaluate reliability of experimental data of the flash points of the flammable mixtures.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.37-45
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• 2009

In this study, experiments of development and application of 50 MPa high-performance concrete are performed for large dimensional tunnel linings. In order to produce 50MPa high-performance concrete, eight optimal mixtures replacing with fly ash and ground granulated blast furnace slag up to 50 percent of type I Portland cement were selected then tests for mechanical properties and simple adiabatic temperature rise tests were carried out. And in order to assess the quantitative characteristics of heat of hydrations of developed mixtures, three mixtures that the type I Portland cement (OPC) and each one mixture of binary and ternary mixtures (BS30, F15S35) were reselected, then the adiabatic temperature rise tests and mock-up tests were performed. Consequently, the comparisons between the results of mock-up tests and finite element analysis can be enhanced the reliability of analyzing routines of thermal behaviours of the developed high-performance concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.693-699
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• 2016

In this study, the replacement effects of cementitious materials (fly ash, blast furnace slag, and blended mixtures) were assessed for normal strength concrete with very low shrinkage properties under $350{\mu}{\varepsilon}$ strain using a powder type shrinkage reducing agent. In addition, through mock-up tests of actual size walls restrained with four sides, the shrinkage characteristics using the power type shrinkage reducing agent were measured and the crack reducing ability was assessed. The slump and air contents were measured as the properties of fresh concrete, and the length changes of the prismatic specimens, $100{\times}100{\times}400mm$ in size, were measured for the shrinkage characteristics. To reduce the shrinkage of concrete, the maximum replacing ratio of the fly ash is effective to 20 percent; however, the use of blast furnace slag and ternary mixtures did not reduce the shrinkage.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.505-508
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• 2008

In this study, temperature increase and strength development of concretes with different types of cement were investigated to construct dam drop spillway. For this purpose, boxes of 1${\times}$1${\times}$1m size with 4 different concrete mixtures were made. The types of concrete were Type I cement concrete, fly ash cement concrete and two type concrete with ternary cement, respectively. The temperature at each point were monitored in these boxes. Based on the Box test, hydration analysis of slab of 2.0m thickness was carried out. This paper presents these experimental and analytical results.