排序方式: 共有37条查询结果,搜索用时 7 毫秒
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Yang-Soon Park Yeong-Keong Ha Sun-Ho Han Kwang-Yong Jee Won-Ho Kim 《Journal of Nuclear Materials》2008,372(1):59-65
A micro X-ray diffractometer with a micrometer sized beam concentrator was developed to investigate the changes in the chemical structures of oxide layers for Zr-based alloys (Zircaloy-4) and Ti metal from the center of the cross section to the surface. Zircaloy-4 and Ti metal were chosen because of their use as a fuel cladding and a heat exchange tubing in a nuclear reactor, respectively. The diffraction patterns were obtained from the cross sectional specimens of the oxidized Zircaloy-4 and Ti metal at 50 μm intervals. For the cross section of Zircaloy-4, Zr metal (hexagonal) was identified in the center, ZrO2−x (hexagonal, about 200 μm in thickness) inside the edge and ZrO2 (monoclinic, about 400 μm in thickness) at the edge. In the case of Ti metal, Ti metal (hexagonal) was identified in the center, TiO (cubic, about 200 μm in thickness) inside the edge and rutile-TiO2 (tetragonal, about 230 μm in thickness) at the edge. From this study, it was concluded that the intermediate phase formed between the fuel and the cladding can be identified by the micro-XRD system. 相似文献
33.
Myung-Won Suh Won-Ho Yang Jonghwan Suhr 《Journal of Mechanical Science and Technology》2001,15(12):1639-1646
It is often necessary that the joint characteristics should be determined in the early stage of the vehicle body design. The researches on identification of joints in a vehicle body have been performed until the recent year. In this study, the joint characteristics of vehicle structure were expressed as the condensed matrix forms from the full joint stiffness matrix. The condensed joint stiffness matrix was applied to typical T-type and Edge-type joints, and the usefulness was confirmed. In addition, it was applied to the real center pillar model and the full vehicle body in order to validate the practical application. 相似文献
34.
So Won-Ho Lee Hae-Chong Kim Young-Chon Roh Sun-Sik 《Photonic Network Communications》2003,5(2):147-162
In this paper, we propose a protocol architecture and quality of service (QoS) supporting algorithms for optical Internet based on optical burst switching (OBS) technology. Firstly, the function of each layer of the protocol architecture and the formats of control packets are defined in order to adopt GMPLS to the control plane of OBS. Then, the offset time decision (OTD) algorithm to cooperate with the proposed protocol architecture is designed for optical Internet. A new burst loss formula taking into account the effect of offset time is introduced to design the OTD algorithm. This algorithm can decide on the appropriate priority-offset time according to the required QoS by using the reversed equation of the so-called heuristic loss formula (HLF) which is approximated as a proportional equation of our new loss formula. Finally, we propose a CAC algorithm based on the OTD algorithm for the purpose of increasing the availability of wavelength resources and supporting the QoS of established connections in optical Internet. The performance of the proposed algorithms is evaluated in terms of burst loss rate and the number of connections through simulation. 相似文献
35.
In this paper, a WDM optical ring consisting of access nodes with fixed transmitter-n fixed receivers (FT—FR
n
) is considered. As access nodes share a wavelength channel there is trade-off between node throughput and fairness among
them. In order to abbreviate the transmission unfairness and to increase the throughput, we propose p-persistent medium access
control (MAC) protocol. Each node uses the carrier sense multiple access with collision avoidance (CSMA/CA) protocol to transmit
packets, and decides whether to use a local empty slot with probability p when a transferred packet based on source-stripping is dropped and emptied. Numerical prediction for the proposed MAC protocol
is introduced to compute the maximum node throughput under uniform traffic condition. For more detail results, we use network
simulation with self-similar traffic and introduce various results. The proposed MAC protocol gives better node throughput
than non-persistent protocol and shows an improved fairness factor than 1-persistent protocol. Through simulation, we also
find the reasonable probability of p-persistent protocol for a given architecture. 相似文献
36.
Won-Ho Lee 《Journal of Mechanical Science and Technology》2002,16(10):1296-1302
A mathematical model for cold rolling and temper rolling process of thin steel strip has been developed using the influence
function method. By solving the equations describing roll gap phenomena in a unique procedure and considering more influence
factors, the model offers significant improvements in accuracy, robustness and generality of the solution for the thin strip
cold and temper rolling conditions. The relationship between the shape of the roll profile and the roll force is also discussed.
Calculation results show that any change increasing the roll force may result in or enlarge the central flat region in the
deformation zone. Applied to the temper rolling process, the model can well predict not only the rolling load but also the
large forward slip. Therefore, the measured forward slip, together with the measured roll force, was used to calibrate the
model. The model was installed in the setup computer of a temper rolling mill to make parallel setup calculations. The calculation
results show good agreement with the measured data and the validity and precision of the model are proven. 相似文献
37.
Kim JY Yoon SB Lee MH Park YJ Kim WH Jee KY 《Journal of nanoscience and nanotechnology》2007,7(11):3862-3866
Synthesis of mesoporous silica microspheres larger than 10 microm via surfactant template approach has rarely been reported. According to the previous studies, particle morphologies were highly variable, depending on the synthesis conditions and impeller design such as impeller type, size, and agitation speed. A new robust surfactant-template synthesis strategy for the stable suspension of large silica microspheres was investigated by introducing an additional cosurfactant. Di(2-ethylhexyl)phosphoric acid (HDEHP) as a cosurfactant played a key role in suspension stabilization without distorting the spherical morphology as well as in the formation of uniform pore structures. High quality of mesoporous silica microspheres was obtained and compared with the Kosuge's silica under different conditions such as stirring rate, acid concentration, the amount of solvent in a mother liquor. 相似文献