• Journal of environmental and Sanitary engineering
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• v.22 no.2
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• pp.75-84
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• 2007

A lysine determination method for low quantity of rice was modified from the original Dye-Binding Lysine (DBL) method used in the national standard in China [GB 4801-84, 1984]. By making use of the property that lysine does not bind to the crocein orange G dye after treated with propionic anhydride, the amount of lysine in rice samples could be determined directly by calculating the difference between the absorbances of the treated and the untreated samples. Various commercial rice samples were purchased from market and evaluated. Several methods were tested by varying both the sizes of the samples and the concentrations of the dye solutions. Results showed that when using 1.284 mM of crocein orange G dye solution and 15.5 mg of sample, the results were most reproducible. The corresponding lysine content in sample were $3.36\;{\pm}\;0.09\;mg/g$ and $3.35\;{\pm}\;0.19\;mg/g$ by traditional method and modified method, respectively. Statistically, there was no significant difference between the results (p>0.05).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.241-250
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• 2006

In the present study, a beach survey such as sand sizes, swim zone widths, and slopes of swash zone has been accomplished for 39 beaches along the Gangwon coastline. The data analysis presents that the swim zone width has a strong correlation with the sand size, showing that the swim zone width is reversely proportional to the 1.1 power of a grain size. The profile factor A has been analyzed using the beach profile form of $h=Ay^{2/3}$, where A was resulted to be proportional to the 0.77 power of a gram size.

• 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.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.61-65
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• 2000

${\beta}$-SiC powder and ${\alpha}$-SiC powders of different particle sizes, containing 5.7wt% $Al_2O_3$ and 4.3wt% $Y_2O_3$ as sintering aids, were hot-pressed at $1780^{\circ}C$ and subsequently annealed at $1950^{\circ}C$ to initiate grain growth. All the hot-pressed and annealed materials consisted of large SiC grains and elongated SiC grains. Typical hardness and fracture toughness of materials for spectacle lens cutting were 15.6 GPa and $5.7MPa{\cdot}m^{1/2}$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.213-216
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• 1995

Strontium niobate, $Sr_2Nb_2O_{7}$ was prepared by the molten stilt synthesis (MSS) and the chemical coprecipitation method (CCP). Single phase $Sr_2Nb_2O_{7}$ was obtained by MSS and CCP at $750^{\circ}C$ and $800^{\circ}C$, respectively. An intermediate phase of composition, $Sr_{5}Nb_4O_{15}$, appeared at $700^{\circ}C$ when CCP method was employed. The resulting powder was observed to have finer particles and more uniform distribution of particle sizes, as compared to those obtained through the conventional method. Such powder characteristics allowed the use of a much lower sintering temperature of $1400^{\circ}C$. Grain-orientation along (0k0) direction, which is advantageous for improving dielectric properties, was also observed. The sintering characteristics and the dielectric properties prepared by MSS and CCP, were better than those by the conventional method.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.799-806
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• 2004

Recently, as the forerunner in establishing the Northeast Asia's logistics base, a lot of marine engineering works such as new ports and container terminals, extension of old ports, new bridges, land reclamation etc. have been progressed. Parallel to it, there is also an increasing demand for improving the safety of construction. In this situation, high resolution seismic reflection profiling can be well used, attempting to classify rocks and sediments under water, if possible, to delineate the distribution of grain sizes in sediments not only for calculating the cost of removing sediments from harbour's channels, but also for estimating the bearing capacities for bridge or port construction. However, the results from the corresponding reflection survey that has been in operation in our country can not be effectively used for engineering purposes mostly due to the insufficient resolution. Thus. in this paper, two innovative strategies are introduced to enhance resolution. The one deals with a newly designed exploration barge that will help reduce several kinds of noises encountered electrically or operationally. The other is associated with an establishment of optimum measuring system comprising e.g. a specially devised hydrophone with a combination of 7 piezoelectric elements. Field experiments performed at Busan harbour are illustrated. The quality of acquired data was thereby fundamentally improved in comparison with that obtained at the same time in a conventional way.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.12
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• pp.1111-1116
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• 2005

ZnO varistor ceramics added a glass-frit 0.03 $wt\%$ were fabricated with variation of sintering temperature. The sintering temperature and time were $1125^{\circ}C\~1200^{\circ}C$ and 2 h. The average grain sizes increased and the varistor voltage decreased with increasing the sintering temperature. The values of the specimen sintered at $1200^{\circ}C$ were $23.7\;{\mu}m$ and 329 V, respectively. The leakage current of all specimens was less than $1\;{\mu}A$ at DC $82\%$ of varistor voltage. The clamping voltage ratio of the specimen sintered at $1175^{\circ}C$ was 1.37. The endurance of surge current and the deviation of varistor voltage of the specimen sintered at $1175^{\circ}C$ were 6400 $A/cm^2$ and ${\Delta}-2.81\%$, respectively. After the High Temperature Load Test(HTLT) at $85^{\circ}C$ for 1000 h, the specimen sintered at $1175^{\circ}C$ showed the lowest deviation of varistor voltage of ${\Delta}-1.92\%$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.603-606
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• 2004

ZnO varistor ceramics were fabricated with variation of addition of $Nd_2O_3$ amount and the sintering temperature was $l150^{/circ}C$. The average grain sizes were showed decreased from $13.8{\mu}m$ to $4.7{\mu}m$, and varistor voltages were increased from 398 V to 657 V by added amount of $Nd_2O_3$. Nonlinear coefficient a of all were with increasing the amount of $Nd_2O_3$ more than 60, in case of added on 0.1mol% $Nd_2O_3$ was 87. And leakage current were less than $1_{\mu}A$ with applied at 82% of varistor voltage. The clamping voltage ratio of the specimes added 0.1mol% $Nd_2O_3$ was 1.38 at applied 25A [$8/20{\mu}s$]. In the specimen added 0.1mol% $Nd_2O_3$, endurence of surge current and deviation of varistor voltage were 7000A/$cm^2$, $\Delta-2.08%$, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.375-378
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• 2004

ZnO varistor ceramics were fabricated with variation of addition of glass-frit amount and the sintering temperature was $1150^{\circ}C$. The average grain sizes were showed decreased from $8.6\;{\mu}m$ to $10\;{\mu}m$, and varistor voltages were decreased from 506 V to 460 V by added amount of glass-frit. Nonlinear coefficient ${\alpha}$, of all were with increasing the amount of glass-frit more than 60, in case of added on 0.03wt% glass-frit was 83. And leakage current were less than $1{\mu}A$ with applied at 82% of varistor voltage. The clamping voltage ratio of the specimes added 0.03wt% glass-frit was 1.41 at applied 25A $[8/20{\mu}s]$. In the specimen added 0.03wt% glass-frit, endurence of surge current and deviation of varistor voltage were $6200A/cm^2$, $\Delta-1.67%$, respectively.

• Transactions on Electrical and Electronic Materials
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• v.4 no.2
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• pp.24-28
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• 2003

(Ba,Sr,Ca)TiO$_3$ powders, prepared by the sol-gel method, were mixed with organic binder and the BSCT thick films were fabricated by the screen printing techniques on alumina substrates. All the BSCT thick films, sintered at 1420$^{\circ}C$, showed the typical XRD patterns of a perovskite polycrystalline structure. The average grain sizes decreased with increasing amounts of ZrO$_2$, and the BSCT(40/40/20) thick films doped with 2wt% MnO$_2$ showed a value of 8$\mu\textrm{m}$. The thickness of thick films by four-cycle on printing/drying was approximately 951$\mu\textrm{m}$. The relative dielectric constant decreased with increasing Ca content and MnO$_2$ doping amount. The relative dielectric constant, dielectric loss and tunability of the BSCT(50/40/10) thick films doped with 2.0wt% ZrO$_2$ were 772, 0.184％ and 15.62%, respectively.