• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.322-325
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• 2006

The nano/microstructure and mechanical properties of the eutectic regions in thixo and rheo cast A356 alloy parts were investigated using nano/micro-indentation and mechanical scratching, combined with optical microscopy and atomic force microscope (AFM).Most eutectic Si crystals in the A356 alloy showed a modified morphology as fine-fibers, however Si particles of network in eutectic region was formed quickly with aging time increase in thixo-cast. The aging responses of the eutectic regions in both the thixo and rheo cast A356 alloys aged at $150^{\circ}C$ for different times (0, 2, 4, 8, 10, 16, 24, 36, and 72 h) were investigated. Both Vickers hardness ($H_V$) and indentation ($H_{IT}$) test results showed almost the same trend of aging curves, the peak was obtained at the same aging time of 10 h.

• Carbon letters
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• v.5 no.4
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• pp.159-163
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• 2004

The polymer-ceramic hybrid, known as 'ceramer', was synthesized by a sol-gel process by incorporating different amount of alkoxide as source of silicon in resorcinol-formaldehyde in presence of basic catalyst to get different percentage of silicon in ultimate carbonized composites. FTIR of the ceramer confirms that it is a network of Si-O-Si, Si-O-$CH_2$ and Si-OH type groups linked with benzene ring. Different amount of silicon in the ceramer exhibits varying temperature of thermal stability and lower coefficient of thermal expansion as compared to pure resorcinol-formaldehyde resin. The lower value of CTE in ceramer is due to existence of silica and resorcinol -formaldehyde in co-continuous phase. Unidirectional composites prepared with ceramer matrix and high-strength carbon fibers show lower value of flexural strength at polymer stage as compared to those prepared with resorcinol-formaldehyde resin. However, after heat treatment to $1450^{\circ}C$, the ceramer matrix composites show large improvement in the mechanical properties, i.e. with 7% silicon in the ceramer, the flexural strength is enhanced by 100% and flexural modulus value by 40% as compared to that of pure resorcinol-formaldehyde resin matrix composites.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1195-1202
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• 1996

To prepare the dielectric thin films of (Pb1-xSrx)TiO3 (x=0.1, 0.2, 0.3, 0.35, 0.5) by the sol-gel process titanium (IV) isopropoxide (Ti[OCH(CH3)2]4) and Pb Sr, acetate were used therefore the thin films were fabricated by dip-coating method. Stability of the sol decreased with addition of Sr content thin films could be fabricated up to 35mol% Over this range precipitation of sol occured thin films couldn't be obtained. Transmittance of thin films at visible range decreased with the increase of heat-treatment temperature but exhibited transmit-tance above 60% in all case. Moreover transmittance of thin films at visible range slightly increased with of addition of Sr,. When thin film containing 30 mol% srontium was heated at 600℃ the best perovskite phase was obtained. The dielectric constant (ε) was 280 and dielectric loss factor (tan δ) was 0.021 and curie tempera-ture (Tc) decreased with the increase of addition of Sr.

• Parasites, Hosts and Diseases
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• v.41 no.3
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• pp.165-169
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• 2003

This study describes the characterization of 80 kDa pretense showing gelationlytic property among three pretenses in the excretory/secretory proteins (ESP) from Toxoplasma gondii. The pretense activity was detected in the ESP but not in the somatic extract of RH tachyzoites. This pretense was active only in the presence of calcium ion but not other divalent cationic ions such as $Cu^{2+},{\;}Zn^{2+},{\;}Mg^{2+},{\;}and{\;}$Mn^{2+}$, implying that $Ca^{2+}$ is critical factor for the activation of the protease. The 80 kDa pretense was optimally active at pH 7.5. Its gelatinolytic activity was maximal at $37^{\circ}C$, and significant level of enzyme activity of the pretense remained after heat treatment at $56^{\circ}C$ for 30 min or $100^{\circ}C$ for 10 min, This thermostable enzyme was strongly inhibited by metal chelators, i.e., EDTA, EGTA, and 11 10-phenanthroline. Thus, the 80 kDa pretense in the ESP secreted by T. gondii was classified as a calcium dependent neutral metalloprotease.

• Textile Coloration and Finishing
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• v.15 no.2
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• pp.59-67
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• 2003

PTT[poly(trimethylene terephthalate)] fiber was annealed by passing on the plate heater to illuminate the effects of annealing on the mechanical properties and dyeability with varying the treatment temperature for 0.5 second. The apparent crystal sizes and crystallinity were increased with increases in temperature. With the increases of the temperature, the dynamic viscoelastic behaviors were analyzed to be reduction in $T_{max} (tan{\delta})$. The initial modulus were observed to be a small enhanced. The shrinkage in hot water were reduced. The dyeability for disperse dye enhanced dramatically, for example, a satisfactory degree of exhaustion was obtained by dyeing at $95^\circ{C}$ for 30 min with the PTT fibers heat treated at $180^\circ{C}$.

• BMB Reports
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• v.35 no.3
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• pp.320-329
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• 2002

A gene, coined tay, for a thermostable DNA polymerase from the novel, extremely thermophilic bacterium Thermoanaerobacter yonseiensis was cloned and expressed in E. coli. Using a DNA polymerase homologous PCR product as a hybridization probe, tay was isolated and sequenced to consist of 2621 nucleotides that encode 872 amino acids. A database analysis showed that DNA polymerase, coined Tay, from T. yonseiensis shared a 39% to 47% identity in the amino acid sequence with those from other DNA polymerases. Tay was overexpressed in E. coli as a fusion protein with a poly-histidine tag at the C-terminus. It was purified by heat treatment, followed by a $Ni^{2+}$-chelate column. The molecular weight of purified Tay was approximately 97 kDa, as shown by SDS PAGE, and it showed high DNA polymerase activity and thermostability. However, it had no 3'$\rightarrow$5' exonuclease activity.

• Journal of Korea Foundry Society
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• v.18 no.4
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• pp.364-372
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• 1998

Effects of Si and Ca additions on the mechanical properties of AM60 based Mg alloys have been investigated. Hardness of the AM60 based Mg alloys reached a maximum value after aging for approximately 33 hours but the amount of hardness increase was negligible. The poor age hardening response of the alloys was due to low Al content, which implies that Al content must be >6 wt.% to observe age hardening effect. The tensile and yield strength increased with increasing Al, Si, and Ca content but elongation decreased with increasing Al and Si content. The best mechanical properties obtained in AM 40-2.5Si-0.2Ca alloy after T4 heat treatment were as follows; tensile strength 193.4 MPa, yield strength 79.2 MPa, and elongation 11.2%. High temperature property obtained from creep test was also improved by introducing $Mg_2Si$ which has high hardness, high melting temperature and low thermal expansion coefficient.

• Conservation and Restoration of Cultural Heritage
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• v.1 no.1
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• pp.9-22
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• 2012

The most widely excavated iron artifacts used as weapons or farm tools from central southern regions of Korea were subjects of non-metallic inclusion analysis through metallographic examination, microhardness measurement, and scanning electron microscopy with energy dispersive X-ray spectroscopy. Through metallographic interpretation and study of the analyzed results, the steel manufacturing and iron smelting using heat processing in the iron artifacts excavated from the central southern region of the ancient Korean peninsula was studied, and the analysis of the non-metallic inclusions mixed within the metallic structures was interpreted as the ternary phase diagram of the oxide to infer the type of iron ores for the iron products and the temperature of the furnace used to smelt them. Most of the ancient forged iron artifacts showed $Al_2O_3/SiO_2$ with high $SiO_2$ contents and relatively low $Al_2O_3$ contents for iron ore, indicating t hat for $Al_2O_3$ below 5%, it is presumed that magnetic iron ores were reduced to bloom iron (sponge iron) with direct-reduction process for production. The temperature for extraction of wustite for $Al_2O_3$ below 1% was found to be $1,020{\sim}1,050^{\circ}C$. Considering the oxide ternary constitutional diagram of glassy inclusions, the steel-manufacturing temperature was presumed to have been near $1,150{\sim}1,280^{\circ}C$ in most cases, and minimum melting temperature of casting iron part excavated in Daeseong-ri. Gyeonggi was near $1,400^{\circ}C$, and it is thought that hypoeutectic cast iron of about 2.3% carbon was casted and fragility of cast iron was improved by decarburizing in solid state.

• Herbal Formula Science
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• v.15 no.2
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• pp.47-64
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• 2007

This report describes 94 prescriptions related to the use of Radix Angelicae Dahuricae main bl ended from Donguibogam. The following conclusions were reached through investigations on the prescriptions that use Radix Angelicae Dahuricae as a key component. 11.7% of wind. 10.6% of carbuncle and deep-rooted carbuncle. recorded the largest number of clinical frequency of the prescriptions in therapeutic use when Radix Angelicae Dahuricae was ta ken as a monarch drug in prescriptions, Prescriptions that utilize Radix Angelicae Dahuricae as t he main component are used in the treatment of apoplexy and carbuncle and deep-rooted carbuncle. headache. wound and they are also used for treating 26 different types of diseases. The prescriptions are compounded with Radix Angelicae Dahuricae as a monarch drug can ap ply to apoplexy, exogenous febrile disease, invasion by wind. wind-cold pathogen, wind-heat path ogen. epidemic disease, pestilence. bruise, bites, deficiency of liver and kidney, deficiency, phlegm-fire, phlegm-heat. The dosage of Radix Angelicae Dahuricae is 0.37g to 7.5g, however 3.75g has be en taken the most for clinical application. The function of Radix Angelicae Dahuricae is to expelling Wind and relieving pain, to expelling wound and forming muscle. to astrict and neutralizing poison. to expelling wind and to getting through body hole. to emit and relieving pain from the combination of drugs and prescriptions.

• Journal of Haehwa Medicine
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• v.14 no.1
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• pp.43-49
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• 2005

One case of patient with urinary retention was reported in this clinical study. After the study, the results were as follows: 1. Anulesis belongs to l$\acute{o}$ng-bi(癃閉) in oriental medicine and the patient of this case belongs to chronic anulesis. 2. The patient of this case was thought as broke out anuresis by vesical nerve palsy of diabetic bladder pathy and sequela of stroke, and ischuria of long lie down 3. The patient of this case changeable process is supposed to urinary frequency, 'bi(閉)', 'l$\acute{o}$ong(癃)', urinary incontinence and urinary frequency. 4. First time of drug treatment is GAMIPHALJENG-SAN(ji$\bar{a}$-w$\grave{e}$i-b$\bar{a}$-h$\bar{e}$ng-s$\check{a}$n) by oral administration that action of alleviate a fever, water utilization and metaphase, convalescence time of drug treatment is PHALMIWANGAMI (b$\bar{a}$-w$\grave{e}$i-w$\acute{a}$n-ji$\bar{a}$-w$\grave{e}$i), YIKLUENG-TANG(yi-ling-t$\bar{a}$ng), CHUKYOO-TANG(s$\grave{u}$-ni$\grave{a}$o-t$\bar{a}$ng) that action of recreation. 5. Accupuncture treatment is s$\bar{a}$n-x$\bar{i}$ng-xuw$\acute{e}$, zw$\acute{u}$-s$\bar{a}$n-li, qi-h$\check{a}$i, gu$\bar{a}$n-yu$\acute{a}$n, zh$\bar{o}$ng-ji by mild supplementing and reducing manipulation of needle and heat accupuncture is qi-h$\check{a}$i, gu$\bar{a}$n-yu$\acute{a}$n, zh$\bar{o}$ng-ji-xu$\acute{e}$. 6. The other treatment is a sitz bath that prevent of urinary tract infection, and relieve of initial acute auresis by using of urethral catheterization.