• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.182-190
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• 2009

In this work, effect of antistrip additives to reduce moisture damage of asphalt mixture were studied. Asphalt antistripping agents were prepared by condensation of formaldehyde with tetraethylene pentamine (TEPA), triethylenetetramine (TETA) and bis(hexamethylene)-triamine (BHMT), respectively. And also the metal type antistripping agent was prepatred by neutralization of stearic acid or palmitic acid with metal hydroxide. Mechanical characteristics of the asphalt mixture added antistripping agent were evaluated with Marshall stability, submerging residuals and coating rate. It was found that antistripping agent prepared in this study reduced moisture damages of asphalt mixtures. In particular, asphalt mixtures added BHMT and C/S (Calcium stearate hydroxide) antistripping agent showed highest submerging and coating rate. Because BHMT and C/S type antistripping agent was to improve bonding between asphalt and aggregate owing to increase of amine concentration and role of metal surfactant.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.329-333
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• 2021

Subcritical water extraction (SWE) is an eco-friendly extraction method that uses only purified water as a solvent under high temperature and high pressure conditions. In this study, total phenolics, and antioxidant activity were evaluated in Ziziphus jujuba Mill extracts from subcritical water obtained by varying the extraction temperature (110-190℃) and extraction time (1-20 min). Total phenolics was maximized with extraction at 190℃ for 15 min (67.79±3.45 mg gallic acid equivalent/g jujube). The 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (48.84±4.74%) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free radical scavenging activity (84.75±1.15%) were maximal at extraction conditions of 190℃, for 20 min. All jujube extracts prepared using SWE had higher total phenolics and antioxidant activities than extracts prepared using organic solvent extraction (60℃, 120 min), including methanol and ethanol. SWE could be an excellent alternative to organic solvents for extracting phenolics and antioxidant compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.171-174
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• 1992

Effects of ascorbic acid and citric acid on pungency and color stabilities in the Horseradish powder during 16 weeks storage were investigated. When the ascorbic arid added 0.1 wt.%, the effect of allyl isothiocynate stability was very significant after 16 weeks storage at 37$^{\circ}C$. However, the effect of citric acid on the allyl isothiocyanate stability was not observed. The results also showed that ascorbic acid and citric arid did not affect the color stability of the Horseradish powder significantly. When the Horseradish powder was tempered with water, the effect of ascorbic acid on stability of allyl isothiocynate and color value was shown.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.532-535
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• 2003

Inhibition effects of enzymatic browning in medical herbs (Paeoniore radix rubra, Pueraria radix, Araliae cordatae radix) by organic acid were investigated. The inhibition effects were in the order of citric acid>ascorbic acid>isoascorbic acid>acetic acid in 1% compound, with no significant difference observed between 1% citric acid and 1% sodium metabisulfite. Results revealed that citric acid was the most effective sulfite substitute agent for the inhibition of enzymatic browning of medical herbs.

• Korean Journal of Food Science and Technology
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• v.23 no.4
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• pp.433-436
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• 1991

Natural compounds which could improve the oxidative stability of fish oil was screened from spices, herbs and naturally occurring antioxidants. Induction period of fish oil determined from oxidation curve by Rancimat ($80^{\circ}C$) was hardly affected with the addition of water-soluble and lipid-soluble fractions of garlic, leek, sesame leave and orange peel, and of organic acids such as citric acid, EDTA and selenium. Caffeic acid, catechin, quercetin and gallic acid laurylester, however, could extend the induction periods by $2.2{\sim}3.8$ times with the addition level of 0.1%(w/w). Rosemary extract and sesamol have a marked effect in retarding oxidation of fish oil. For example, induction periods of the oil samples stabilized with 0.1 rosemary extract and 0.1 sesamol were 16.4 hr and 11.6 hr, respectively, as compared to 4.0 hr of a control. When rosemary extract was used in combination with ascorbic acid (0.02%) or 8-tocopherol (0.2%), induction period could be extended to ca. 28 hr due to the synergism.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.107-115
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• 2017

In this study, the surface check reduction effect of preservative-treated Korean larch round-wood was investigated by applying three physical treatments, such as incising, kerfing, and kiln-drying. Moreover, the possibility of long-term service life was also checked by comparing the depth of surface check and the penetration depth of preservative. A rapid gradient of wood moisture content between surface and center causes a surface check. Thus, the effect of reducing surface check was carried out at the lowest equilibrium moisture content (EMC) condition, temperature ($2^{\circ}C$), humidity (44.6%), in outdoor locations in Korea until the test specimens reach to the 8.6% EMC. As a result, the preservative-treated specimens without incising, kerfing, kiln-drying (Type C) could not ensure the long-term service life due to a large surface check. Because the surface check depth of all specimens was deeper than the penetration depth of preservative. In case of the incising treated specimens (Type I), 80% of them, the depth of surface check was not deeper than the penetration depth of preservative. However, when a kerfing was additionally treated (Type B), a possibility of happening deeper surface check than penetration depth of preservative was increased rather than Type I.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.25-32
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• 2012

The thickness of anti-freezing layer has been empirically determined using the frost depth obtained from the freezing index and has not been generally considered as a structural layer in pavement design procedure. In fact, the anti-freezing layer makes a role in structural layer and enables to reduce the total thickness of pavement system. The objective of this study is to develop the statistical regression model for evaluating the structural capacity of anti-freezing layer using Falling Weight Deflectormeter(FWD) test data in asphalt pavements. The FWD testing was conducted at the embankment, cutting, and boundary area of various test sections to estimate the structural capacity of anti-freezing layer in different foundation condition. It is observed from this testing that the center deflections of pavement structure with anti-freezing layer are smaller than those without anti-freezing layer ranging from 0.4 to 82.6%. To determine the variables of statistical model, the correlation study has been conducted between various FWD deflection indexes and the anti-freezing layer thickness. It is found that the ${\Delta}BDI$(%)(${\Delta}Basin$ Damage Index(%)) is highly correlated with anti-freezing layer thickness. The ${\Delta}BDI$(%) model were developed for evaluating structural capacity of anti-freezing layer using linear mixed-effect models.

• Journal of Preventive Medicine and Public Health
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• v.15 no.1
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• pp.33-46
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• 1982

In Korea BCG vaccination has been employed as the main control measure for tuberculosis since 1962. Recently, the protective efficacy of BCG against tuberculosis has been controversial worldwide. A case-control study was conducted to evaluate the efficacy of BCG in Korea which has a high prevalence of tuberculosis(2.5%). The study subjects were children under the age of 14 years who were hospitalized and diagnosed as tuberculosis in three general hospitals in Taegu City during last 6 years ($1975{\sim}1980$). Among 416 hospitalized tuberculous patients, 314 cases were confirmed as to the presence or absence of the BCG scar. A control group was selected from the same hospital patients of the same period as the cases. The control group was other than tuberculous patients whose distribution of age, sex and residence were the same as the cases. The results obtained are as follows: For all forms of tuberculosis, the relative risk and the protective efficacy of BCG were 3.5 and 71.8%. The efficacy was higher among female than among male (78.6% vs. 65.8%). The efficacy was higher among the one year and above than among less than 1 year of age. For tuberculous meningitis, the relative risk and the protective efficacy of BCG were 3.9 and 74.3 %. The efficacy was statistically significantly higher among female than among male (p<0.05). The relative risk and the protective efficacyt of BCG for uberculous meningitis combined with miliary tuberculosis and combined with pulmonary tuberculosis represented 6.9, 85.6%, and 7.4, 86.5%, respectively. On the other hand, the relative risk and the protective efficacy of BCG for miliary tuberculosis were 2.1 and 51.6%, and for pulmonary tuberculosis, 2.3 and 54.7%, respectively. From these results, it appears that BCG vaccination is an efficient preventive measure in Korea where tubercluosis is prevalent. Thus the routine BCG vaccination should be continued.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.69-76
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• 2012

An achieving method of highly progressive pressure gradient is presented to enhance the missile ejection system's performance by using a gas generator in the condition of preventing erosive burning. To obtain and confirm a stable burning, a ground burning test was performed to evaluate the new methods of a radial-hole and a multi-row propellant grain. The test results show that a radial-hole grain takes good effect on erosive burning and not on ejection performance. On the other hand, a multi-row grain which reduces the length-to-diameter ratio(L/D) of grain is very effective to prevent the erosive burning and to enhance the ejection performance simultaneously.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.432-439
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• 2011

An achieving method of highly progressive pressure gradient is presented to enhance the missile ejection system's performance by using a gas generator in the condition of preventing erosive burning. To obtain and confirm a stable burning, a ground burning test was performed to evaluate the new methods of a radial-hole and a multi-row propellant grain. The test results show that a radial-hole grain takes good effect on erosive burning and not on ejection performance. On the other hand, a multi-row grain which reduces the legnth-to-diameter ratio(L/D) of grain is very effective to prevent the erosive burning and to enhance the ejection performance simultaneously.