• Nuclear Engineering and Technology
• /
• v.52 no.8
• /
• pp.1714-1723
• /
• 2020

This study aims at characterizing the rheological properties of uranium oxide powders for nuclear fuel pellets manufacturing. The flowability of these powders must be compatible with a reproducible filling of press molds. The particle size distribution is known to have an impact on the rheological properties and fine particles (<100 ㎛) are suspected to have a detrimental effect. In this study, the impact of the particle size distribution on the rheological properties of UO₂ powders was quantified, focusing on the influence of fine particles. Two complementary approaches were used. The first approach involved characterizing the powder in a static state: density, compressibility and shear test measurements were used to understand the behavior of the powder when it is transitioned from a static to a dynamic state (i.e., incipient flow conditions). The second approach involved characterizing the behavior of the powder in a dynamic state. Two zones, corresponding to two characteristic behaviors, were demonstrated for both types of measurements. The obtained results showed the amount of fines should be kept below 10 % wt to ensure a robust mold filling operation (i.e., constant mass and production rate).

• Journal for History of Mathematics
• /
• v.20 no.4
• /
• pp.1-21
• /
• 2007

We investigate the Gou Gu Shu(句股術) in Hong Jung Ha's Gu Il Jib(九一集) and Cho Tae Gu's Ju Su Gwan Gyun(籌書管見) published in the early 18th century. Using a structural approach and Tien Yuan Shu(天元術), Hong has obtained the most advanced results on the subject in Asia. Using Cho's result influenced by the western mathematics introduced in the middle of the 17th century, we study a process of a theoretical approach in Chosun mathematics in the period.

• Asian-Australasian Journal of Animal Sciences
• /
• v.14 no.12
• /
• pp.1719-1723
• /
• 2001

The effect of slaughter weight and gender on fatty acid composition of homogenised rib samples of Hungarian Simmental (HS) and Holstein-Friesian (HF) cattle breeds was investigated. In the first experiment 22 Hungarian Simmental and 18 Holstein-Friesian cattle's meat, in the second experiment 15 females and 12 males Holstein-Friesian cattle's meat was analysed on fatty acid content. Saturated and mono- or polyunsaturated fatty acid profile did not seem to vary either by breed or by slaughter weight categories. The effect of gender, however, proved to be significant in influencing the quantity of polyunsaturated fatty acids, including linoleic and linolenic acids, as well as polyunsaturated fatty/saturated fatty acids (PUFA/SAFA) ratio. The amount of polyunsaturated fatty acids (PUFA) was higher in males than in females. Negative correlation was established between the quantity of PUFA and the amount of adipose tissue in rib samples.

• Asian-Australasian Journal of Animal Sciences
• /
• v.30 no.12
• /
• pp.1718-1723
• /
• 2017

Objective: The study explored the dynamics of shearing force and its correlation with chemical compositions and in vitro dry matter digestibility (IVDMD) of stylo. Methods: The shearing force, diameter, linear density, chemical composition, and IVDMD of different height stylo stem were investigated. Linear regression analysis was done to determine the relationships between the shearing force and cut height, diameter, chemical composition, or IVDMD. Results: The results showed that shearing force of stylo stem increased with plant height increasing and the crude protein (CP) content and IVDMD decreased but fiber content increased over time, resulting in decreased forage value. In addition, tall stem had greater shearing force than short stem. Moreover, shearing force is positively correlated with stem diameter, linear density and fiber fraction, but negatively correlated with CP content and IVDMD. Conclusion: Overall, shearing force is an indicator more direct, easier and faster to measure than chemical composition and digestibility for evaluation of forage nutritive value related to animal performance. Therefore, it can be used to evaluate the nutritive value of stylo.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1718-1723
• /
• 2003

This paper presents a computational method for deformation modes of a flexible body in multibody system from the experimental modal analysis and an efficient method for flexible multibody dynamic analysis by use of the modes. It is difficult to directly use experimental modal parameters in flexible multibody dynamic analysis. The major reasons are that there are many inconsistencies between experimental and analytical modal data and experimental noises are inherent in the experimental data. So two methods, such as, a method for ortho-normalization of experimental modes and the other one for mode expansion, are suggested to gain deformation modes of a flexible body from the experimental modal parameters. Using the virtual work principle, the equation of motion of a flexible body is derived. The effectiveness of the proposed method will be verified in the numerical example of cab vibration of a truck by comparing analysis and test results.

• Korean Journal of Materials Research
• /
• v.26 no.1
• /
• pp.13-16
• /
• 2016

Morphology and formation processes of lamellar grain boundaries in titanium rich binary TiAl intermetallics were studied. TiAl alloys containing aluminum content of 44 to 48 at.% were induction-heated to 1723 K followed by helium-gas-quenching at various temperatures. For the Ti-44%Al, few lamellae were observed in samples quenched from higher than 1473 K. Although small peaks of beta phase were detected using X-ray diffraction, only the ordered hexagonal phase (${\alpha}_2$) with clear APB contrast was observed in TEM observation. For the Ti-48 at.%Al alloy, almost no lamellar structure, and straight grain boundaries were observed in samples quenched from higher than 1623 K. The formation of lamellae along grain boundaries was observed in the sample quenched from 1573 K. The fully lamellar microstructures with serrated boundaries were observed in samples quenched from lower than 1473 K. It was found that the formation of ${\gamma}$ platelets took place at higher temperatures in Ti-48 at.%Al than in Ti-44 at.%Al. Although the size of the serration is different, serrated lamellar grain boundaries could be obtained for all alloy compositions employed. The serration appeared to be due to the grain boundary migration induced by precipitation and growth of ${\gamma}$. Differences in transformation characteristics with aluminum content are discussed.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.12B
• /
• pp.1712-1723
• /
• 2001

This paper presents a design procedure and manufacturing techniques realizing of a 5.8 GHz duplexer based on cylindrical coaxial dielectric resonator. Upto Q$\times$f$\_$o/=30,000 cylindric coaxial dielectric resonator was developed control by addition of dielectric materials. This resonator shows attenuation characteristics -40 dB for transmitter and -50 dB for receiver by consisting of two sets of 4-stage cavity resonator within f$\_$o/$\pm$10 MHz bandwidth which was requirement of DSRC. Employing the measurement results, design procedure to characterize the transmission and reflection properties are presented.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.11 no.3
• /
• pp.1719-1723
• /
• 1969

In this country, farmers lay out furrows in the direction which is considered by their own judgement to be convenient for cultivation without paying much attention for soil erosion. The direction of furrow has considerable effects on soil and water losses. In this experiment, it is intedned to observe the differences of soil and water losses in different directions of furrows of sloped fields so that the results thus obtained could be informed to farmers who should be careful in determining furrow direction for soil erosion control. Some the major experimental results are summarized as follows: The direction of furrows did not affect so much on the runoffs in a gentle slope, as the runoff is 509 ton/10a in the contouring plot, $51^{\circ}$/ton/10a in the 45-degree plot, and 560 ton/10a in the up-and-down hill plot. The contouring plot among the three plots had best effect on soil conservation, as the soil losses are 5.8 ton/10a in the contouring plot, 9.3 ton/10a in the 45 degree plot, and 10.2 ton/10a in the up-and-down hill plot.

• Proceedings of the KSR Conference
• /
• 2008.06a
• /
• pp.1712-1723
• /
• 2008

In the trackbed design using an elastic multi-layer model, the stress-dependent resilient modulus is the key input parameter, which reflects substructure performance under repeated traffic loading. The prediction models of resilient modulus of crushed stone and weathered granite soil were developed from nonlinear dynamic stiffness, which can be combined by in-situ and laboratory seismic measurements. The models accommodate the variation with the deviatoric and/or bulk stresses. To investigate the performance of the prediction models proposed, the elastic response of the test trackbed near PyeongTaek, Korea was evaluated using a 3-D nonlinear elastic computer program (GEOTRACK) and compared with measured elastic vertical displacement caused by the passages of freight and passenger trains. The material types of the test sub-ballasts are crushed stone and weathered granite soil, respectively. The calculated vertical displacements within the sub-ballasts are within the order of 1mm, and agree well with measured values with the reasonable margin. The prediction models are thus concluded to work properly in the preliminary investigation.

• Journal of Ocean Engineering and Technology
• /
• v.27 no.2
• /
• pp.8-12
• /
• 2013

Four kinds of silicon nitride composites with tri-laminate structure were prepared by stacking tapes with aligned ${\beta}-Si_3N_4$ whisker seeds. The composites were fabricated using a modified tape casting method for enhanced alignment of the whisker seeds. The relative densities of all four samples reached 99% at room temperature. The three-point flexural strengths of the samples according to the stacking sequences were measured at both room temperature and 1723 K. The high temperature strength of sample WWW was $457{\pm}14$ MPa. The fracture of sample WWW occurred mainly along the grain boundary. The room temperature strengths of samples OOO, OWO, WOW, and WWW were $430{\pm}32$ MPa, $470{\pm}19$ MPa, $700{\pm}14$MPa, and $940{\pm}14$ MPa, respectively.