• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.771-775
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• 1997

Treatment with electron beam irradiation was investigated for the elimination of Escherichia coli O157:H7 which has been linked to outbreaks of foodborne illness on undercooked and raw meat. Before treatment, the maximum populations were observed at 16 hr when E. coli O157:H7 was incubated in TSB at $37^{\circ}C$. Incubation at $4^{\circ}C$ did not influence survival and growth of the strain. The numbers of E. coli O157:H7 were present about $10^{7}\;CFU/mL$ in the log $(6\;hr\;at\;37^{\circ}C)$ and stationary phase $(16\;hr\;at\;37^{\circ}C)$ of cells, respectively. Freezing $(24\;hr\;at\;-18^{\circ})$ had a more marked lethal effect. The $D_{10}$ value at $-18^{\circ}C$ of E. coli O157:H7 contaminated in frozen beef was 0.45 kGy, and inactivation factor were $6.67{\sim}11.11$ at the radiation doses of $3{\sim}5\;kGy$. Therefore, electron beam irradiation was an effective method to eleminate of E. coli O157:H7.

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1115-1120
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• 1998

The sliding wear behavior of Ni-base hardfacing alloy, Deloro 50, was investigated at the contact stresses of 15ksi and 30ksi under the various wear environments. In air at room temperature, Deloro 50 showed lower wear resistance than Stellite 6 even at 15ksi due to the occurrence of severe adhesive wear. This seems to be caused by the lower hardness and work- hardening rate of Deloro 50 than those of Stellite 6. In water at room temperature, Deloro 50 showed as good wear resistance as Stellite 6 at 15ksi. It was considered to be due to that water could effectively prevent metal to metal contact through contacting asperities. However, Deloro 50 showed severe adhesive wear at 30ksi in water at room temperature. It seems to be that the water could not suppress adhesion wear at 30ksi. At $300^{\circ}C$ in air, Deloro 50 exhibited higher wear resistance than Stellite 6 even at 30ksi. It was considered that the oxide glaze layers formed on wear surface during sliding, effectively prevented direct metal-to-metal contacts.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.899-904
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• 2002

Aloe and propolis are extensively used in folk medicine. Ethanol extracts of Aloe vera (AE), ethanol extract of propolis (PE) and waxfree extract of propolis (PW) were prepared to test antimicrobial activities against five oral microorganisms (Streptococcus mutans, Enterococcus faecalis, Enteococcus hirae, Escherichia coli, Candida albicans). Antimicrobial activities were tested by serial broth dilution method and expressed by minimal inhibitory concentration (MIC). The AE showed relatively weak antimicrobial activities, while both of PE and PW greatly inhibited all microorganisms tested. To investigate the antimicrobial effects of the combined extracts of aloe with propolis, the fractional inhibitory concentration index (FICI) was determined by checkerboard assay for each strain. The combination of AE with PE or PW resulted in Synergistic effect against oral microorganisms tested (FICI=0.375) except Escherichia coli (FICI=1.0 for PE, FICI=0.75 for PW).

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.116-124
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• 2015

The objective of this study is to evaluate the effects of the replacement levels of grinded fly-ash on the repaired mortar based on a polymer. The main parameters are the curing temperature and replacement levels of grinded fly-ash. The curing temperature and the replacement levels of grinded fly-ash are varied at $40^{\circ}C$, $20^{\circ}C$ and $5^{\circ}C$, and between 0% and 35% of the total binder by weight, respectively. The flow in fresh mortar and compressive strengths according to ages, the relationship of stress-strain, elastic modulus and modulus rupture in hardened mortar, as well as scanning the electron microscopy and the X-ray diffraction of mortar, were measured, respectively. The test results showed that the flow, elastic modulus and modulus rupture are great in mortar specimens with 20~30% of the replacement levels of grinded fly-ash. In addition, compressive strengths according to ages were affected by the replacement levels of grinded fly-ash and the curing temperature indicated that the strength development ratio of mortar with 20% of the replacement levels of grinded fly-ash was greater than others. In the prediction of the compressive strength specified by the ACI 209 code, the strength development at an early and late age can be generalized by the functions of the replacement levels of grinded fly-ash and the curing temperature. In the analysis of scanning the electron microscopy and the X-ray diffraction, the number and intensity of peaks increased and the form of CSH gels on the surface of the particle of grinded fly-ash was observed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.322-328
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• 2002

This study was carried out to investigate antimutagenic and anticancer effects of ethanolic extract of Korean traditional doenjang added sea tangle. Most of the mineral content of doeniang was increased by addition of sea tangle. In the Ames test, the antimutagenic effect of ethanol extract of Korean traditional doenjang added 5% sea tangle was higher than that of control (no additive), 10%, and 15% sea tangle additions. The inhibition rate of ethanol extract (200$\mu\textrm{g}$/plate) of doenjang added 5% sea tangle in the S. typhimurium TA100 strain showed 97.0% inhibition against the mutagenesis induced by MNNG. In addition, the suppression of ethanol extract (200$\mu\textrm{g}$/plate) of doenjang added 5% sea tangle in the S. typhimurium TA98 and TA100 strains showed 60.2% and 69.1% inhibition respectively, against the mutagenesis induced by 4NQO. The suppressions under the same condition against B($\alpha$ )P and Trp-P-1 in the TA98 and TA100 strains were 71.7% and 87.3%, and 66.6% and 80.8%, respectively. In the anticancer effects, the cytotoxicity of doenjang added 5% sea tangle on the cell lines with human lung carcinoma (A549), human hepatocellular carcinoma (HepG2), and human gastric carcinoma (KATOIII) were inhibited with increasing the extract concentration. The treatment of 1.0 mg/mL Doenjang added 5% sea tangle showed strong cytotoxicity of 56.4%, 87.67%, and 89.5% against A549, HepG2, and KATOIII, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.2
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• pp.192-201
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• 1985

Two experiments, utilizing 204 broiler chicks of the Maniker strain, were conducted to study the effects of dried whey and chitin on the growth of chicks. In the first experiment, diets containing 5%, 10%, or 15% dried whey, or a control diet with no whey, were fed to chicks from 1 day to 4 weeks of age. There were no significant differences among the dietary groups, with respect to the rate of growth or protein or feed efficiency. In the second experiment, chicks were fed with diets containing no whey, 2% chitin, 20% dried whey, or 20% dried whey plus 2% chitin, from 1 day to 4 weeks of age. Adverse effects (diarrhea, crooked toes and enlarged cecum) were observed in the group fed 20% dried whey. The protein efficiency ratio (PER) and feed efficiency ratio (FER) tended to improve in the dietary groups with dried whey, as compared to the control group. No significant differences were observed in the total carcass nitrogen and lipid levels of dietary groups. But the chitin-supplemented diets tended to improve on the growth rate compared to the groups without chitin. The results of the two experiments suggest that the growing broiler chick can tolerate up to 15% dried whey in the diet, without any harmful effect on growth. Also, chitin may improve the poorer growth rate of chicks fed dried whey, but not all of the adverse effects of whey.

• Geophysics and Geophysical Exploration
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• v.10 no.3
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• pp.203-210
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• 2007

As a part of basic studies on monitoring of landslides and slope stability using SP measurements, micro-electric potentials of rock samples were measured accompanied with the rock failure by a uniaxial loading test were measured. The measurement system consists of a 8 channel A/D converter with 24 bit resolution, uniaxial loading tester, strain gages and 4 sets of electrode attached to a rock sample. Rock samples of granite, limestone, and sandstone were tested. Also, mortar samples were tested in order to monitor electric-potentials of a uniform sample. Micro-electric potentials were detected in all saturated samples and the strength of them increased as the loading force increased. Sandstone samples showed the largest strength of micro-electric potential and it followed limestone and granite samples, which indicates a positive relationship with porosity of rocks. The mechanism generating these micro-electric potential can be explained in terms of electro-kinetics. In case of dry samples, micro-electric potential could be observed only in sandstone samples, where piezoelectric effect played main role due to high contents of quartz in sandstone samples. We found that biggest micro-electric potentials were observed at the electrodes near the crack surface of rock samples. This is very encouraging result that SP monitoring can be applied to predicting landsliding or to estimate collapsing position combining with monitoring of acoustic emissions.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.5
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• pp.556-575
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• 2001

For the improvement of denture fitness of changed residual ridge, denture liner can be used. Denture liner should be very stable physically in various environments of the mouth as well as be bonded strongly with denture resin. In this study. the specimens bonded with four kinds of soft denture liner and three kinds of hard denture liner were used to test the physical properties of the liners. All experimental groups were stored in $37{\pm}1^{\circ}C$ distilled water for 24hours, followed by thermocycling between $15^{\circ}C$ and $45^{\circ}C$ with 15 second dwell time. 1000, 2000, 3000 cycles of thermocycling were excuted and physical properties were measured by Instron Universal Testing Machine. The obtained results were as follows : 1. In tensile bond test of sea liners, it was shown that both of $Molloplast-B^{(R)}$ specimens before and after thermocycling had the highest tensile strength, and in case of hard liners, Dura-Liner $II^{(R)}$ specimen had the highest tensile strength before and after thermocycling. Depending on thermocycling, $Soft-Relining^{(R)}$, $Denture-Relining^{(R)}$, $Molloplast-B^{(R)}$, $Coe-Soft^{(R)}$ and $Kooliner^{(R)}$ specimen showed significant difference(p<0.05). 2. In strain test of soft liners, it was shown that $Molloplast-B^{(R)}$ specimen before thermocycling and the $Coe-Soft^{(R)}$ after thermocycling showed highest results, and in case of hard liners, the Dura-Liner $II^{(R)}$ specimen before and after thermocycling had the highest result. Depending on thormocycling, $Denture-Relining^{(R)}$, $Molloplast-B^{(R)}$ and Dura-Liner $II^{(R)}$ specimen showed significant difference(p<0.05). 3. In maximum distance test of soft liners. the $Molloplast-B^{(R)}$ specimen before thermocycling and the $Coe-Soft^{(R)}$ after thermocycling showed highest results. and in case of hard liners, the Dura-Liner $II^{(R)}$ specimen before and after thermocycling showed highest result. Depending on thermocycling, $Denture-Relining^{(R)}$, $Molloplast-B^{(R)}$ specimens showed significant difference(p<0.05). 4. In elasticity test of soft liners, the $Molloplast-B^{(R)}$ specimen before and after thermocycling showed highest result. and in case of hard liners, the Dura-Liner $II^{(R)}$ specimen before thermocycling and the $Tokuso-Rebase^{(R)}$ after thermocycling showed highest results. Depending on thermocycling, $Soft-Relining^{(R)}$ $Molloplast-B^{(R)}$ specimens showed significant difference (p<0.05).

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.53-64
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• 2017

Ultra-high performance fiber-reinforced concrete (UHPFRC) is characterized by a post-cracking residual tensile strength with a large tensile strain as well as a high compressive strength. To determine a material tensile strength of UHPFRC, three-point loading test on notched prism and direct tensile test on doubly notched plate were compared and then the design tensile strength is decided. Shear tests on nine I-shaped beams with varied types of fiber volume ratio, shear span ratio and size effect were conducted to investigate shear behavior in web. From the test results, the stress redistribution ability represented as diagonal cracked zone was quantified by inclination of principal stress in web. The test results shows that the specimens were capable of resistance to shear loading without stirrup in a range of large deformation and the strength increase with post-cracking behavior is stable. However at the ultimate state all test specimens failed as a crack localization in the damaged zone and the shear strength of specimens is affected by shear span ratio and effective depth. Strength predictions show that the existing recommendations should be modified considering shear span ratio and effective depth as design parameters.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.33-43
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• 2005

This work reports results of our study on the dynamic responses of the buried pipelines both along the axial and the transverse directions under various boundary end conditions. In order to investigate the effect of the boundary end conditions for the dynamic responses of the buried pipeline, we have devised a computer program to find the solutions of the formulae on the dynamic responses (displacements, axial strains, and bending strains) under the various boundary end conditions considered in this study, The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. We have observed a resonance when the mode wavelength matches the wavelength of the seismic wave, where the mode number(k) of resonance f3r the axial direction. On the other hand, we have not been able to observe a resonance in the analysis of the transverse direction, because the dynamic responses are found to vanish after the seventh mode. From the results of the dynamic responses at many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement, the strain and its position.