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71.
Woo‐Jin Byun Bong‐Su Kim Kwang Seon Kim Ki‐Chan Eun Myung‐Sun Song Reinhard Kulke Olaf Kersten Gregor Möllenbeck Matthias Rittweger 《ETRI Journal》2010,32(2):195-203
A new vertical transition between a substrate integrated waveguide in a low‐temperature co‐fired ceramic substrate and an air‐filled standard waveguide is proposed in this paper. A rectangular cavity resonator with closely spaced metallic vias is designed to connect the substrate integrated waveguide to the standard air‐filled waveguide. Physical characteristics of an air‐filled WR‐22 to WR‐22 transition are compared with those of the proposed transition. Simulation and experiment demonstrate that the proposed transition shows a ?1.3 dB insertion loss and 6.2 GHz bandwidth with a 10 dB return loss for the back‐to‐back module. A 40 GHz low‐temperature co‐fired ceramic module with the proposed vertical transition is also implemented. The implemented module is very compact, measuring 57 mm × 28 mm × 3.3 mm. 相似文献
72.
Muhammad Mostafa Monowar Muhammad Mahbub Alam Md. Obaidur Rahman Choong Seon Hong Sungwon Lee 《电信纪事》2010,65(11-12):777-794
Being a pivotal resource, conservation of energy has been considered as the most striking issue in the wireless sensor network research. Several works have been performed in the last years to devise duty cycle based MAC protocols which optimize energy conservation emphasizing low traffic load scenario. In contrast, considering the high traffic situation, another research trend has been continuing to optimize both energy efficiency and channel utilization employing rate and congestion control at the MAC layer. In this paper, we propose A Load-aware Energy-efficient and Throughput-maximized Asynchronous Duty Cycle MAC (LET-MAC) protocol for wireless sensor networks to provide an integrated solution at the MAC layer considering both the low-and high-traffic scenario. Through extensive simulation using ns-2, we have evaluated the performance of LET-MAC. LET-MAC achieves significant energy conservation during low traffic load (i.e., no event), compared to the prior asynchronous protocol, RI-MAC, as well as attains optimal throughput through maximizing the channel utilization and maintains lower delay in regard to the CSMA/CA-like protocol during a high volume of traffic (i.e., when an event occurs). 相似文献
73.
Recently, multipath routing in wireless sensor networks (WSN) has got immense research interest due to its capability of providing increased robustness, reliability, throughput, and security. However, a theoretical analysis on the energy consumption behavior of multipath routing has not yet been studied. In this paper, we present a general framework for analyzing the energy consumption overhead (i.e., energy tax) resulting from multipath routing protocol in WSN. The framework includes a baseline routing model, a network model, and two energy consumption schemes for sensor nodes, namely, periodic listening and selective wake-up schemes. It exploits the influence of node density, link failure rates, number of multiple paths, and transmission environment on the energy consumption. Scaling laws of energy-tax due to routing and data traffic are derived through analysis, which provide energy profiles of single-path and multipath routing and serve as a guideline for designing energy-efficient protocols for WSN. The crossover points of relative energy taxes, paid by single-path and multipath routing, reception, and transmission, are obtained. Finally, the scaling laws are validated and performance comparisons are depicted for a reference network via numerical results. 相似文献
74.
Won‐Kee Hong Seon‐Chee Park Jin‐Min Kim Seung‐Geun Lee Seung‐Il Kim Ki‐Joon Yoon Ho‐Chan Lee 《The Structural Design of Tall and Special Buildings》2010,19(3):275-289
An experimental investigation of composite beams composed of wide flange steel and precast concrete is presented. The bottom flange of the steel section is encased in precast concrete. Utilizing the merits of both steel and concrete material, the size of the steel beams can be reduced without sacrificing performance. The bottom flange of the steel beam is reinforced with concrete at a manufacturing plant, eliminating the use of temporary pour forms. The composite beams were tested to investigate how the size of the wide flange steel and how the top and bottom reinforcements influence the behaviour of the beams. Flexural load carrying capacity, load displacement relationships and failure modes were examined. The test specimens were T‐shaped composite beams with slabs, each measuring 10‐m long. The flexural moment strength of all of the composite beams—at both the yield limit state and the maximum load limit state—was measured and compared with the analytical flexural capacity. The stiffness degradation, ductility and dissipating energy capabilities of the composite beams were investigated based on the hysteresis curves. The composite beams tested in this study successfully reduced both the floor height of the building and the size of the steel beams needed to meet code requirements. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
75.
Jeon Onyu Kim Hyun-Guk Kook Junghwan Kim Seon Man Wang Semyung 《Journal of Mechanical Science and Technology》2022,36(7):3313-3327
Journal of Mechanical Science and Technology - The radiated sound power in an enclosure with a vent hole is actively controlled by radiation mode. Active structural acoustic control (ASAC), which... 相似文献
76.
In this article, we propose the method of the multicriteria alternative selection under uncertainty. The basis of the method is the principle of the Bellman–Zadeh fuzzy measures intersection and nine‐point linguistic rating scale of Saaty. The novelty of the method presented here consists of the fact that it does not require labor‐intensive procedures, requiring arraying and array processing of paired comparisons matrix. Instead, special correlations are used, which are based on the comparison with the worst alternative and the least important criterion. As an example for the utilization of our method, we use the problem for choosing cars. © 2010 Wiley Periodicals, Inc. 相似文献
77.
Jun Duk Bin Kim Seon K. Park Myoung H. Bae Moon S. Park Yoon S. Joo Young J. 《Telecommunication Systems》2000,14(1-4):311-319
Forecasting a new service diffusion process is critical in designing marketing strategies and analyzing the costs and benefits
for service providers. It is very difficult, however, in cases that data are not available. We suggest the combination of
analogy and survey to forecast the demand for Low Earth Orbit (LEO) mobile satellite service in Korea. First, we analyze the
diffusion of existing mobile phone service, which is similar to LEO service. The diffusion parameters for mobile phone service
are then used in a model for LEO service. A survey was made on two hundred fifty‐five subscribers of existing mobile phone
service in Korea. We estimate the potential market size of LEO service by applying the logit model to the survey data. Then,
we forecast the annual demand for LEO service in Korea from 1998 to 2005. We also derive the price elasticity of market potential
of LEO service.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
78.
Seong Je Jeon Sang Man Koo Seon Am Hwang 《Solar Energy Materials & Solar Cells》2009,93(6-7):1103-1109
Screen-printed n+–p–p+ solar cells were fabricated on Cz single crystalline Si material, with a 45 Ω/sq emitter and PECVD SiNx antireflective coating with a thickness of 700 Å, using different Ag pastes and commercial leaded reference paste (CN33-462, Ferro Corp.). Ag and Al contacts were co-fired using a mass-production line equipped with mesh belt conveyer furnace systems (Centrotherm thermal solution GmbH & Co. KG). The average results for single crystalline Si solar cells (156 cm2) are: Isc=5.043 A, Voc=0.621 V, Rs=0.0087 Ω, Rsh=15.3 Ω, FF=0.773, and Eff=16.45%. Rsh and fill factor values of fabricated cells were slightly higher when compared with the commercial leaded Ag paste, although cells were fabricated by metallizing the lead-free silver pastes. For the lead-free Ag paste used in this study, the line pattern continuity is retained with improved edge definition in sharp contrast to that of reference Ag paste. Average value of Rs was also equivalent approximately to that of the leaded Ag paste. 相似文献
79.
80.
Seon Yang Youngjoong Ko 《Pattern recognition letters》2011,32(2):293-296
In this paper, we study how to extract comparative sentences from Korean text documents. We decompose our task into three steps: (1) collecting comparative keywords; (2) extracting comparative-sentence candidates by keyword searching; and (3) eliminating non-comparative sentences from these candidates using machine learning techniques. We perform various experiments to find relevant features. As a result, our experiments show significant performance, an F1-score of 90.23%. 相似文献