• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.107-108
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• 2006

The effect of WC or NbC addition on various properties of Ti(C0.7N0.3)-Ni cermets was investigated. The microstructure oj Ti(C0.7N0.3)-xWC-20Ni showed a typical core/rim structure, irrespective of the WC content, whereas the structure oj Ti(C0.7N0.3)-xNbC-20Ni was different and was dependent on the NbC content. The hardness (HV) and the fracture toughness (KIC) had a tendency to increase marginally, while the coercive force (HC) and the magnetic saturation $(4{\pi}{\sigma})$ decreased gradually with an increase in WC or NbC content in the systems studied. In addition, increasing WC content in Ti(C0.7N0.3)-xWC-20Ni system, decarburization was retarded, while denitrification was accelerated

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.229-233
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• 2003

By using an oxynitride glass as a sintering additive, the effects of BN content on microstructure and mechanical properties of the hot-pressed and subsequently annealed SiC-BN composites were investigated. The microstructures developed were analyzed by image analysis. The morphology of SiC grains was strongly dependent on BN content in the starting composition. The aspect ratio of SiC decreases with increasing BN content and the average diameter of SiC shows a maximum at 5 wt% BN and decreases with increasing BN content in the starting powder. The fracture toughness increased with increasing BN content while the strength decreased with increasing BN content. The strength and fracture toughness of SiC or SiC-TiC composites were strongly dependent on the morphology of SiC grains, but the strength and fracture toughness of SiC-BN composites were strongly dependent on BN content rather than morphology of SiC grains. These results suggest that fracture toughness of SiC ceramics can be tailored by manipulating BN content in the starting composition. Typical fracture toughness and strength of SiC-10 wt% BN composites were 8 MPa$.$m$\^$1/2/ and 445 MPa, respectively.

• Journal of Bio-Environment Control
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• v.14 no.3
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• pp.144-148
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• 2005

Kale leaf had similar contents of vitamin C, $NO_3$, p, Ca, Mg, and Fe with reported values. Among these internal quality factors, $NO_3$ content which has been a concern recently, ranged from 139 to 429 mg in 100 g fresh kale leaf, Kale showed high vitamin C content ranging from 106 to 203 mg in 100 g fresh leaf. The relative concentration of chlorophyll and b value color had a high correlation coefficient (r) with vitamin C, $NO_3$, Mg and Fe content. The relationship between $NO_3$ content and the relative concentration of chlorophyll was given by the following linear equation: $NO_3$ content : 21.55 + (5.907 ${\times}$ the relative concentration of chlorophyll) with an r of $0.910^{{\ast}{\ast}}$. Correlation between $NO_3$ content and b value was also very dependable (r = $-0.901^{{\ast}{\ast}}$). Vitamin C content and the relative concentration of chlorophyll showed a high correlation, r = $-0.858^{{\ast}{\ast}}$. Among internal quality factors, vitamin C content increased with decreasing $NO_3$ content and their correlation coefficient was high (r = $-0.795^{{\ast}{\ast}}$). Consequently, $NO_3$ content of kale leaf could be inferred from an external nondestructive method, such as the relative concentration of chlorophyll. We may be able to produce high quality kale leaves containing high amount of vitamin C and low content of $NO_3$ using this method.

• The Korean Journal of Ceramics
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• v.3 no.3
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• pp.199-207
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• 1997

$Al_2O_3$/SiC particulate composites were fabircated by pressureless sintering. The dispersed phase was SiC of which the content was varied from 1.0 to 10 vol%. Three SiC powders having different median diameters from 0.28 $\mu\textrm{m}$ to 1.9 $\mu\textrm{m}$ were used. The microstructure became finer and more uniform as the SiC content increased except the 10 vol% specimens, which were sintered at a higher temperature. Under the same sintering condition, densification as well as grain growth was retarded more severly when the SiC content was higher or the SiC particle size was smaller. The highest flexural strength obtained at 5.0 vol% SiC regardless of the SiC particle size seemed to be owing to the finer and more uniform microstructures of the specimens. Annealing of the specimens at $1300^{\circ}C$ improved the strength in general and this annealing effect was good for the specimens containing as low as 1.0 vol% of SiC. Fracture toughness did not change appreciably with the SiC content but, for the composites containing 10 vol% SiC, a significantly higher toughness was obtained with the specimen containing 1.9$\mu\textrm{m}$ SiC particles.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.289-301
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• 1995

The effect of Air/$C_3H_8$ gas addition on the compound layer growth of steels nitrocarburised in $NH_3+Air+C_3H_8$ mixed gas atmospheres was investigated. It is considered that amount of residual $NH_3$ was varied according to alternation of Air/$C_3H_8$ mixing ratio and volume content. The compound layer formed from nitrocarburising was composed of ${\varepsilon}-Fe_{2-3}$(C, N) and ${\gamma}^{\prime}-Fe_4$(C, N). According as Air/$C_3H_8$ mixing ratio increased, the superficial content of ${\gamma}^{\prime}-Fe_4$(C, N) within the compound layer was increased, at the same time the growth rate of compound layer and porous layer was increased. In the case of alloy steel at the fixed gas composition, the growth rate of compound layer and porous layer was worse than carbon steel and compound layer phase composition structure primarily consisted of E phase. As the carbon content of materials was increasing in the given gas atmospheres, the growth rate of compound layer and porous layer was increased and the superficial content of ${\varepsilon}-Fe_{2-3}$(C, N) within the compound layer was increased.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.352-353
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• 2006

The effect of TiC content on oxidation behavior of the sintered WC-TiC-TaC alloys with 2 mass% TaC and different TiC amounts of 3-45 mass% was investigated through oxidation tests in air at 973K. As a result of the tests, it was revealed that with increasing TiC content in the alloys, mass changes caused by oxidation and thickness of the scale decreased. Thus, it is considered that the main component of the scales changed gradually from $WO_3$ to $TiO_2$ with increasing TiC content in the alloys, and oxygen diffusion through the scale to the alloys was inhibited gradually.

• Journal of Environmental Health Sciences
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• v.23 no.2
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• pp.44-56
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• 1997

When sewage sludge is treated by cornposting, higher moisture content and lower C/N ratio on sewage sludge is problems. This paper project to alesolve two problems. The almost trends in run 3 of MC 70% are similar to these in run 1 and 4 of MC 65%. A retention time of the highest temperature (>50$\circ$C) and increase rate of temperature in run 3 are an affinity to these in run 4. Particularly, decrease rate of temperature in run 3 is slower than others and this data shows the more activity of thermal microbial in run 3 than that in others. C/N ratio trends in run 3 shows slow reaction in initial stage but, after 9 days, is similar to that in run 1 and 4. Carbon trends in each run are a similarity to C/N ratio trends. Temperature, MC, carbon and C/N ratio trends in run 5, whose C/N ratio is 15, show less microbial activity than that in run 6, whose C/N ratio is 20. But temperature increase of the beginning stage and pH of the final stage in run 5 are greater than that in run 6. Final MC and carbon content in run 5 and 6 have a similar values. That is, final MC in run 5 and 6 is 49.39% and 48.97% and final carbon content in each run is 25.15% and 22.20%. Expecially, a temperature increase and C/N ratio decrease rate of the beginning stage in run 5 are greater than these in run 6. This shows the shorter lag time in run 5 than lag time in run 6.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.1
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• pp.23-26
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• 1985

This experiment was investigated on weight loss, vitamin C content, and its relationship to evaluate visual quality during spinach consignment from a viewpoint of consumer. Vitamin C content of spinach leaf, 35.38mg% fresh weight, was 3 times higher than those of stem. Under $20^{\circ}C$ of spinach consignment, the spinach was edible in a half day of unpackage and 3 days with package. However, under $10^{\circ}C$ of spinach consignment, it was good through 6-7 days with unpackged and 10 days with package. Weight and vitamin C content of stem and leaf in spinach during consignment were closely related to the temperature condition at $20^{\circ}C$ than at $10^{\circ}C$ in both of package and unpackage. The regression equation of relationship between loss(X) and vitamin C loss(Y) of spinach, during consignment with Package and unpackage at $20^{\circ}C$ and $10^{\circ}C$ was Y=21.30X+40.32(r=0.69.)

• Journal of Powder Materials
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• v.5 no.4
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• pp.286-292
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• 1998

Ni$_3$Al intermetallic compound has been tested as a binder phase, in order to improve the oxidation resistance and the mechanical properties of TiC-Ni cermet at a high temperature. The wettability of $Ni_3Al$ on TiC and the optimum sintering condition were investigated in TiC-(30, 40) vol% $Ni_3Al$ cermets with the sintering temperature (1380~$1430^{\circ}C$) and time (30~99 min). The results are summarized as follows: 1) Ni$_3$Al showed good wettability on TiC above 1400$^{\circ}C$ ; 2) The shrinkages of the specimens increased with the sintering temperature, the sintering time and the binder content, whereas the relative densities were decreased; 3) Any other phase did not appeared in the microstructures of all sintered cermets. The grain sizes of TiC became larger as the sintering temperature and the sintering time as well as the binder content increased; 4) The hardness of the cermets decreased with increase in the sintering temperature and the sintering time as well as the binder content; 5) The transverse-rupture strength of the cermets increased with the sintering temperature and the sintering time, whereas it decreased with the binder content.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.3
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• pp.179-183
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• 1998

The cyanidin 3-glucoside (C3G) extracted from pigmented rice seeds in 0.5% TFA (Trifluoro acetic acid) -95% ethanol was separated by High Performance Liquid Chromatography (HPLC). A HPLC system using a Develosil ODS-5 column and 0.1 % TFA-$H_2O$～0.1 % TFA-$CH_3CN$ gradient elution was selected for separation and quantitative determination of C3G. Regression equation obtained for the standard content of C3G pigment was as Y=21.95293$^*$X-14.726771 (r=0.99$^{**}$). Using this method, 326 domestic and introduced collections were evaluated for the C3G content. The Korean bred cultivar 'Heugjinjubyeo', showed highest C3G content (552 mg/100g seed) among the tested cultivars. Among the pigmented rice cultivars ten cultivars were selected for containing a high content of C3G. The content of C3G per 100g seeds was in high order as follows: Heugjinjubyeo (552mg)>Cheng Chang (321mg)>Kilimgeugmi (240mg)>PI160979-2 (224mg)>Hong Shei Lo (221mg)>Heugnambyeo (191 mg)>Mitak =PIl60979-1 (186mg)>Suwon425 (163mg)>Sanghaehyanghyeolla (108mg). The C3G pigment was not detected in the common white rice cultivars.