• Carbon letters
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• 제9권3호
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• pp.210-217
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• 2008

Petroleum pitch and coke with wet mixture method or with dry mixture method were investigated to develop the composite anodic carbon material of high power lithium ion battery. Cokes coated with pitch were obtained by the heat treatment of mixture of cokes and pitch with different weight ratios at $800{\sim}1200^{\circ}C$. The charge and discharge characteristic of the consequent composite anodic carbon material assembled in batteries was tested. Cokes with wet mixture method have a smooth surface and their capacity changed little with changing temperature and content as compared to the cokes with dry mixture method. Although the reversible capacities showed different values by the anode manufacturing method, the composite anode with the mixture of 20 wt% of petroleum pitch and 80 wt% of coke showed the higher power capability and initial efficiency than the pitch based anode. However, the reversible capacity of the composite anode showed the reduced value as compared with the pitch based anode.

• 열처리공학회지
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• 제19권2호
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• pp.90-95
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• 2006

Nitriding or carburizing of carbon steels results in good mechanical properties such as high surface hardness and wear resistance but it has no affection on the corrosion resistance. Corrosion properties of nitriding and carburizing steels could be deteriorated. So, recently, there have been great demand for oxi-nitriding to enhance both mechanical properties and corrosion resistance. In this study, the corrosion resistance of carbon steel, S35C, and free cutting steel, SUM222, are prepared by vacuum nitriding and vacuum post-oxidation were compared with those treated by nitriding. After vacuum post-oxidation, $5{\mu}m$ oxide layer was formed on the nitride layer with $20{\sim}30{\mu}m$ depth. Potentio-dynamic polarization curve in corrosion test showed that the corrosion potential after post oxidation was increased from 200 mV to 800 mV in S35C and from 600 mV to 1200 mV in SUM222. SEM analyses showed that pores was increased and surface roughness became rougher with post oxidation. However, the formation of $Fe_3O_4$ resulted in the enhanced corrosion resistance of steels.

• 헤리티지:역사와 과학
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• 제34권
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• pp.196-209
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• 2001

Kunjung-mun Gate the only existing multi-level palace gate from the Chosun Dynasty, is the main fate of Kungjung-jun, the central building of Kyungbok-koong Palace. Sangryangmun(a written record of the construction of the ridge beam) of Kunjung-mun Gate was discovered in a hole under its main beam during the renovation project on September 19th, 2000. At the time of discovery, Sangryangmun was found in its original state as a rolled up scroll. On a clould-patterned, red silk cloth, 78 cm in width and 1200 cm in length, each of all 92 lines of the Kunjung-mun Sangryangmun is comprised of either 7 or 11 brush-written, ornamental "Seal" characters. With an exception of its discoloration, the material is considered well preserved. After its discovery, the National Institute of Cultural Properties stored the document in an airtight container for a permanent preservation. In accordance to the Royal Command at the time, the Kunjung-mun Sangryangmun was composed by Kim Byungi, then written by Lee Donsang on January 19th 1867. This document records the meaning and the process of the repair effort of Kunjung-mun Gate includes the wish for peace and longevity of the Chosun Kingdom and its people.

• Bulletin of the Korean Chemical Society
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• 제17권4호
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• pp.321-324
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• 1996

Sr1+xSm1-xFeO4-y solid solutions with a composition range 0.00 ≤x≤1.00 have been prepared at 1200 ℃ in air under normal atmospheric pressure. All the solutions exhibit the K2NiF4-type structure of tetragonal system. Mohr salt analysis shows that the mole ratio of Fe4+ ion to Fe3+ ion or the τ value increases with the x value. Nonstoichiometric chemical formulas have been formulated from the x, τ, and y values. Electrical conductivity was measured in the temperature range of 173-373 K under atmospheric air pressure. The conductivities of each sample are varied within the semiconductivity range. The conductivity at constant temperature increases steadily with x value and activation energies are varied from 0.14 to 0.32 eV. The conduction mechanism of the ferrite system may be proposed as a hopping model of conduction electrons between the mixed valence states. The Mossbauer spectrum for the composition of x=0.00 shows a six line pattern by which the existence of Fe3+(I.S.=0.32 mm/sec) can only be identified. The spectra for the compositions of x=0.50 and 1.00 presents broad single line patterns showing a mixed valence state.

• 대한금속재료학회지
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• 제47권10호
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• pp.629-634
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• 2009

The effects of processing parameters on the surface properties of the hardened layers processed by the low temperature plasma nitrocarburizing and the low temperature two-step plama treatment (carburizing+nitriding) were investigated. The nitrogen-enriched expanded austenite structure (${\gamma}_N$) or S phase was formed on all of the treated surface. The surface hardness reached up to 1200 $HV_{0.025}$, which is about 5 times higher than that of untreated sample (250 $HV_{0.1}$). The thickness of hardened layer of the low temperature plasma nitrocarburized layer treated at $400^{\circ}C$ for 40 hour was only $15{\mu}m$, while the layer thicknesss in the two-step plama treatment for the 30 hour treatment increased up to about $30{\mu}m$. The surface thickness and hardness increased with increasing treatment temperature and time. In addition, the corrosion resistance was enhanced than untreated samples due to a high concentration of N on the surface. However, higher treatment temperature and longer treatment time resulted in the formation of $Cr_2N$ precipitates, which causes the degradation of corrosion resistance.

• Journal of Microbiology and Biotechnology
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• 제32권2호
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• pp.248-255
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• 2022

Phlebia sp. MG-60 is the salt-tolerant, white-rot fungus which was isolated from a mangrove forest. This fungus expresses three kinds of manganese peroxidase (MGMnP) isozymes, MGMnP1, MGMnP2 and MGMnP3 in low nitrogen medium (LNM) or LNM containing NaCl. To date, there have been no reports on the biochemical salt-tolerance of these MnP isozymes due to the difficulty of purification. In present study, we established forced expression transformants of these three types of MnP isozymes. In addition, the fact that this fungus hardly produces native MnP in a high-nitrogen medium (HNM) was used to perform isozyme-selective expression and simple purification in HNM. The resulting MGMnPs showed high tolerance for NaCl compared with the MnP of Phanerochaete chrysosporium. It was worth noting that high concentration of NaCl (over 200 mM to 1200 mM) can enhance the activity of MGMnP1. Additionally, MGMnP1 showed relatively high thermo tolerance compared with other isozymes. MGMnPs may have evolved to adapt to chloride-rich environments, mangrove forest.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.781-789
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• 2022

KHNP had licensed Dynamic Control rod Reactivity Measurement (DCRM) method using detector current signals of PWRs in 2006. The method has been applied to all PWRs in Korea for about 15 years successfully. However, the original method was inapplicable to PWRs using low-sensitivity integral fission chamber as ex-core detectors because of their pulse pile-up and the nonlinearity of the mean-square voltage at low power region. Therefore, to overcome this disadvantage, a modified method, DCRM-EK, was developed using kinetics behavior after equilibrium condition where the pulse counts maintain the maximum value before pulse pile-up. Overall measurement, analysis procedure, and related computer codes were changed slightly to reflect the site test condition. The new method was applied to a total of 15 control rods of 1000 MWe and 1400 MWe PWRs in Korea with worths in the range of 200 pcm -1200 pcm. The results show the average difference of -0.4% and the maximum difference of 7.1% compared to the design values. Therefore, the new DCRM-EK will be applied to PWRs using low sensitivity integral fission chambers, and also can replace the original DCRM when the evaluation fails by big noises present in current or voltage signals of uncompensated/compensated ion chambers.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1026-1029
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• 2006

Particulate reinforced titanium composites were produced by PM rout. Differents volumetric percentages of TiN reinforcements were used, 5,10,15 vol%. Samples were uniaxial pressed and vacuum sintered at differents temperatures between $1200-1300^{\circ}C$. Density, porosity, shrinkage, mechanical properties and microstructure were studied. Elastic properties and strength resistance were analysed by flexural strength and tension tests, and after the test, fractured samples were analysed too, obtaining a correlation between the fracture, interparticulated or intraparticulated, and the reinforcement addition.. Hardness and microhardness test were applied too, in order to complete the study about mechanical properties. In order to study wear resistance pin-on-disc test were used. In addition, the temperature influence, the reactivity between matrix and reinforcement, and the microstructures developed were observed by optical and electron microscopy.

• 한국초전도ㆍ저온공학회논문지
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• 제12권3호
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• pp.44-48
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• 2010

Acoustic emission (AE) signal from an HTS tape has a low signal to noise ratio, due to the large amount of noise caused by the boiling of the liquid cryogen or mechanical vibration from the cryo-cooler. In an attempt to improve the sensitivity of the AE sensor, $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt.% $Nb_2O_5$ ceramics sintered at $1200^{\circ}C$ was synthesized. In addition, the resonance ($f_r$) and anti-resonance frequencies ($f_a$) were measured using the specimens with various thicknesses (1.0, 1.5, 2.0, 2.5 and 3.0 mm). According to the test results, large AE signals with high frequencies were obtained from the AE sensor fabricated using a piezoelectric disc with a thinner thickness.

• 운동영양학회지
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• 제16권1호
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• pp.11-17
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• 2012

The purposes of this study were to investigate the effects of acute exercise on blood vaspin, glucose level, and inflammatory cytokines in middle-aged women with pre-diabetes. Nineteen middle-aged women (normal women, n = 11) and women with pre-diabetes(n = 8), who were apparently healthy and not taking any medications affecting their blood pressure or blood glucose, participated. Body fatness parameters including body mass index, body fat percentage, and waist circumference were measured using a bio-impedance analyzer. Resting blood pressure was measured in duplicate, and mean values were used for the data analysis. Regardless of group assignments, all subjects participated in a 3-day consecutive walking exercise at an intensity of 65% VO_2max targeting an energy expenditure of 1200 kcal (400 kcal per day). The major outcome variables included total cholesterol, triglycerides, high-density lipoprotein cholesterol, glucose, vaspin, interleukin-6, and adiponectin levels. Unlike normal women, women with pre-diabetes had a significant improvement in the homeostatic model assessment of insulin resistance (p < 0.025) with no significant group difference in response to acute exercise. The findings suggest that acute exercise results in a significant improvement in insulin sensitivity without any change in serum vaspin levels in women with pre-diabetes.