• Steel and Composite Structures
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• v.2 no.4
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• pp.247-258
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• 2002

The high-temperature material properties of steel are very important to the fire resistance analysis of high-strength bolt connections. This paper reports on the results of the experimental studies on the high-temperature properties of 20 MnTiB steel which is widely used in high-strength bolts, and the friction coefficient of 16Mn steel plates at elevated temperature which is a necessary parameter for bolted frictional connection analysis. The test data includes yield strength, limit strength, modulus of elasticity, elongation and expansion coefficient of 20MnTiB steel at elevated temperature, and the friction coefficients between two 16Mn steel plates under elevated temperatures and after cooling. Based on the data from the tests, the mathematical models for predicting the mechanical properties of 20MnTiB steel and friction coefficients of 16Mn steel plates have been established.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.610-613
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• 2020

Specimens of austenitic stainless steel were irradiated with 6 MeV Xe ions to two doses of 7 and 15 dpa at room temperature and 300 ℃ respectively. Then partial irradiated specimens were subsequently thermally annealed at 550 ℃. Irradiation-induced BCC-phase formation and magnetism were analyzed by grazing incidence X-ray diffraction (GIXRD) and vibrating sample magnetometer (VSM). It has been shown that irradiation damage level, irradiation temperature and annealing temperature have significant effect on BCC-phase formation. This BCC-phase changes the magnetic behavior of austenitic stainless steel. The stress relief and compositional changes in matrix are the driving forces for BCC-phase formation in austenitic stainless steel during ion irradiation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.163-166
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• 2004

Integrated Ship-Shore Information System makes use of advanced technology of marine mobile communication and extends the computer network of shipping company to ship. This system conveniently accomplishes the information exchange between company and ship, guarantees navigation safety and improves commercial performance. The framework of integrated ship-shore information system and the analysis of its function are provided in this paper. Meanwhile, the idea based on the specification of J2EE to build this system is put forward and the relevant technology is demonstrated.

• Journal of Information Display
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• v.13 no.1
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• pp.1-6
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• 2012

Decreasing the thermal resistance is the critical issue for high-brightness light-emitting diodes. In this paper, the effects of some design factors, such as chip size (24 and 35 mil), substrate material (AlN and high-temperature co-fired ceramic), and die-attach material (Ag epoxy and PbSn solder), on the thermal-dissipation characteristics were investigated. Using the thermal transient method, the temperature sensitivity parameter, $R_{th}$ (thermal resistance), and junction temperature were estimated. The 35-mil chip showed better thermal dissipation, leading to lower thermal resistance and lower junction temperature, owing to its smaller heat source density compared with that of the 24-mil chip. By adopting an AlN substrate and a PbSn solder, which have higher thermal conductivity, the thermal resistance of the 24-mil chip can be decreased and can be made the same as that of the 35-mil chip.

• Journal of Communications and Networks
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• v.7 no.4
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• pp.408-416
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• 2005

Quality of service (QoS) provision is an important and indispensable function for multi-service wireless networks. In this paper, we present a new scheduling/admission control frame­work, including an efficient rate-guaranteed opportunistic scheduling (ROS) scheme and a coordinated admission control (ROS­CAC) policy to support statistic QoS guarantee in multi-service wireless networks. Based on our proposed mathematical model, we derive the probability distribution function (PDF) of queue length under ROS and deduce the packet loss rate (PLR) for individual flows. The new admission control policy makes admission decision for a new incoming flow to ensure that the PLR requirements of all flows (including the new flow) are satisfied. The numerical results based on ns-2 simulations demonstrate the effectiveness of the new joint packet scheduling/admission control framework.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.106.1-106
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• 2001

American options no doubt is invariably more popular than European options, due to the fact that it gives the owner the option to exercise a contract before and up to the expiration date, unlike an European option, which only allows the owner to exercise a contract on the date of expiration. Owing to its popularity, many methods like the binomial numerical method and the pseudo American method have been devised for computing of the value of the American options. The aim of this research is to develop an effective 3-dimensional visualization for American option portfolio based on the Geske-Roll-Whaley model. It is obvious that it is extremely tedious and unadvisable for researchers to interprte chunks of data by looking at graphs or pie charts, which are simple but not effective for analyzing important dta. Hence, the generation of the Geske-Roll-Whaley ...

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.390.2-390
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• 2002

The stability ratio and vibrational amplitude of each tube inside a steam generator have different values. We estimate the characteristics of flow-induced vibration for CE type steam generator with various column and row number of the tube. To obtain the thermal-hydraulic data and stability ratio we use the ATHOS3 and PIAT-FEI/TE code respectively. It turns out that the steam generator has a bounded central zone which the distributed values of the stability ratio and the vibrational amplitude, and those values across the zone boundary become decreased.

• Structural Engineering and Mechanics
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• v.57 no.3
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• pp.389-402
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• 2016

Based on the traditional mechanical model of thin-walled straight beam, the paper makes analysis and research on the pre-twisted thin-walled beam finite element numerical model. Firstly, based on the geometric deformation differential relationship, the Saint-Venant warping strain of pre-twisted thin-walled beam is deduced. According to the traditional thin-walled straight beam finite element mechanical model, the finite element stiffness matrix considering the Saint-Venant warping deformations is established. At the same time, the paper establishes the element stiffness matrix of the pre-twisted thin-walled beam based on the classic Vlasov Theory. Finally, by calculating the pre-twisted beam with elliptical section and I cross section and contrasting three-dimensional solid finite element using ANSYS, the comparison analysis results show that pre-twisted thin-walled beam element stiffness matrix has good accuracy.

• Steel and Composite Structures
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• v.21 no.3
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• pp.553-571
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• 2016

The progressive collapse potential of steel moment framed structures due to abrupt removal of a column is investigated based on the energy principle. Based on the changes of component's internal energy, this paper analyzes structural member's sensitivity to abrupt removal of a column to determine a sub-structure resisting progressive collapse. An energy-based structural damage index is defined to judge whether progressive collapse occurs in a structure. Then, a simplified beam damage model is proposed to analyze the energies absorbed and dissipated by structural beams at large deflections, and a simplified modified plastic hinges model is developed to consider catenary action in beams. In addition, the correlation between bending moment and axial force in a beam during the whole deformation development process is analyzed and modified, which shows good agreement with the experimental results.

• Wind and Structures
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• v.12 no.3
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• pp.281-283
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• 2009

Marquardt method is used to estimate the aerodynamic parameters in urban area of Beijing City, China, including displacement length (d), roughness length ($z_0$) and friction velocity (u*) and drag coefficient. The surface drag coefficient defined as the ratio between friction velocity and mean wind speed is 0.125 in our research, which is close to typical urban area value. The averaged d and $z_0$ are 1.2 m and 7.6 m. d and $z_0$ change with direction because of the surface heterogeneity over urban surface and reach their maximum values at S-SW sector, this tendency agrees with the surface rough element distribution around the observation tower.