• Applied Microscopy
• /
• v.47 no.3
• /
• pp.121-125
• /
• 2017

This study deals the prediction of temperature effect on low-frequency dispersion of alternating current (AC) conductivity spectra of composite materials based on copolymer reinforced with carbon black (CB) particles. A sample of ethylene butylacrylate loaded with 13% of CB particles were prepared and investigated using the impedance spectroscopy representation in the frequency range from 40 Hz to 0.1 MHz and temperature range from $20^{\circ}C$ to $125^{\circ}C$. The dielectric constant, ${\varepsilon}^{\prime}$, and dielectric losses, ${\varepsilon}^{{\prime}{\prime}}$, were found to decrease with increasing frequency. The frequency dependence of the AC conductivity follows the universal power law with a large deviation in the high frequency region, the positive temperature coefficient in resistivity effect has been observed below the melting temperature which makes this composite potentially remarkable for industrial applications.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.19 no.1
• /
• pp.21-26
• /
• 1990

The aim of this study is to investigate effects of Prunus mume extract on gastric secretion in rats and experimentally carbon tetrachloride-induced liver damage of rabbits. The groups of Prunus mume extract showed excellent increasing effect in total acidity and peptic activity and decreasing effect on gastric volume than the control group whereas clear differences were not found between sample adminstered group and control group in gastric pH. In liver function test Prunus mume extract exhibited rapid recuperation of liver function that is sGPT activity showed an apparant decreasing effect from the 6th day total cholesterol and alkaline phosphatase level from the 10th day respectively compared to the control group in carbon tetrachloride-intoxicated rabbits. It is, is suggested that Pruns mume extract can be used as the stomachics to promote the gastric digestion by increasing the peptic activity and health food to shorten the recovery time from liver diseases.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.4 no.4
• /
• pp.141-148
• /
• 2000

Recently the Carbon Fiber Sheet(CFS) is widely used for strengthening damaged RC structures. Strengthening compression members such as column can increase ductility and strength due to the confinement effect. In this experiment, the behavior of concrete cylinders confined by CFS was examined. The confinement pressure is increased linearly as axial stress is increased in low axial stress, and the confinement effect of CFS was rapidly developed after near maximum axial stress, thus axial strength and ductility was improved. As the ratio of CPS is increased, concrete cylinders failed due to local fracture of CFS. The confinement effect of circular section is more efficient than that of rectangular section. And significant improvement of axial strength, axial strain, transverse strain at failure is observed in circular section. This is because in rectangular section the local fracture of CFS near corner may be occured, thus the strain efficiency ratio must be considered for RC structures with CFS.

• Journal of the Korean Society of Safety
• /
• v.18 no.3
• /
• pp.101-108
• /
• 2003

Polymeric positive temperature coefficient(PTC) composites have been prepared by incorporating carbon black(CB) into high density polyethylene(HDPE), polyphenylene sulfide(PPS) and polybutylene terephthalate(PBT) matrices. A PTC effect was observed in the composite, caused by the large thermal expansion due to He consecutive melting of HDPE, PPS and PBT crystallites. This theory is based upon the premise that the PTC phenomenon is due to a critical separation distance between carbon particles in the polymer matrix at the higher temperature. The influence of PTC characteristics of the PPS/CB composite can be explained by DSC result. HDPE, one of prepared composition, exhibit the higher performance PTC behavior that decreaseing of negative temperature coefficient(NTC) effect and improved reproducibility by chemically crosslinking. Also, PBT/CB and PPS/CB composites exhibit the higher PTC peack temperature than HDPE/CB PTC composite, individually $200^{\circ}C$ and $230^{\circ}C$. These PTC composite put to good use in a number of safety application, such as self$.$controlled heater, over-current protectors, auto resettable switch, high temperature proctection sensor, etc.

• Advances in aircraft and spacecraft science
• /
• v.6 no.1
• /
• pp.1-18
• /
• 2019

This present article represents the study of the forced vibration of nanobeam of a single-walled carbon nanotube (SWCNTs) surrounded by a polymer matrix. The modeling was done according to the Euler-Bernoulli beam model and with the application of the non-local continuum or elasticity theory. Particulars cases of the local elasticity theory have also been studied for comparison. This model takes into account the different effects of the interaction of the Winkler's type elastic medium with the nanobeam of carbon nanotubes. Then, a study of the influence of the amplitude distribution and the frequency was made by variation of some parameters such as (scale effect ($e_0{^a}$), the dimensional ratio or aspect ratio (L/d), also, bound to the mode number (N) and the effect of the stiffness of elastic medium ($K_w$). The results obtained indicate the dependence of the variation of the amplitude and the frequency with the different parameters of the model, besides they prove the local effect of the stresses.

• Korean Journal of Pharmacognosy
• /
• v.33 no.4 s.131
• /
• pp.324-331
• /
• 2002

This study was performed to investigate the protective effect of Houttuynia cordata Thunb on hepatotoxicity in carbon tetrachloride$(CCI_4)$ intoxicated rats. The examined effects hexane, chloroform, butanol and water fractions prepared from the Houttuynia cordata Thunb methanol exlract and rats were administrated with those orally once a day for successive 6 days, fellowed by treaoent with $CCl_4$ on the sixth day. After 6 days, the activities of aminotransferase, alkalinephosphatase, ${\gamma}-glutamyl$ transpeptidase, lactate dehydrogenase and contents of triglyceride, hepatic lipid peroxide in butanol fraction pretreated rats were significantly decreased compared to the only $CCl_4$ treated rats, also depletion glutathione content induced by treatment with $CCl_4$ was prevented by butanol fraction pretreated rats. In addition, activities of hepatic superoxide dismutase, catalase, glutathione peroxidase in butanol fiaction pretreated rats were significantly decreased compared to the only $CCl_4$ treated rats, but the activity of hepatic glutathione-S-transferase was not significantly effect. These results suggest that butanol fiuction of Houttuynia cordata Thunb methanol extract have potent hepatoprotective effect against carbon tetrachloride intoxicated rats.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.3
• /
• pp.99-104
• /
• 2020

Modern people spend a lot of time indoors. Oil mist has a very fatal effect on the cook's health. Range Hood's filter plays a very important role in removing oil mist from kitchen. In this study, we applied coanda effect to increase the collection efficiency of filter. Original, Bottom, Slide Three shapes were simulated, and the two shapes were measured and compared using a wind tunnel tester. Pressure loss is measured below 2.0mmAq for all three filters, making them easy to use indoors. The simulation results were 15% for the original filter, 22% for the bottom filter, and 30% for the slide filter. The wind tunnel tester obtained 26% of the original filter and 30% of the slide filter. Research is needed to increase the collection efficiency by 50%.

• Carbon letters
• /
• v.26
• /
• pp.95-101
• /
• 2018

• Korean Journal of Organic Agriculture
• /
• v.20 no.2
• /
• pp.161-172
• /
• 2012

This study was carried out to estimate carbon footprint and to establish of LCA of garlic production system. We have case study in cultivate garlic 1 kg calculate in carbon footprint. LCA carried out to estimate carbon footprint and to establish of LCI (life cycle inventory) database of garlic production system. The data is from Research of Farmer's income in 2010 (RDA, 2011), and used Pass (5.0.0) program. The value of fertilizer, amount of pesticide input were shown the environmental effect and direct emission. Carbon footprint in agriculture guarantees the choice right the consumer to choose the lower carbon goods. Its can make to strengthen of agriculture and food industry's reduction effort of $CO_2$. Nowadays consumer requests food's safety and environment friendly process. Carbon footprint also needs consumer's relief and incentives.

• Carbon letters
• /
• v.5 no.2
• /
• pp.75-80
• /
• 2004

The studies on activated carbon prepared from walnut shell and groundnut shell were undertaken to ascertain the effect of initial state of precursor and activation process on the development of porosity in the resulting activated carbon. Walnut shell based carbon shows the presence of cellular pores while Groundnut shell based carbon shows fibrillar pore structure. The adsorption parameters, characterization of product and scanning electron microscopic studies carried out showed the presence of mainly Micro, Meso and Macro porosity in carbon prepared from Walnut shell while mainly micro porosity was observed in Groundnut shell based activated carbon. An interrelationship between the adsorption efficiency and porosity in terms of quality control parameters, for before and after activation, was validated through the scanning electron microscopic data.