• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.435-442
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• 2002

In a multicell box structure, distortional warping normal stress due to warping of cross section and transverse bending normal stress of walls due to distortion of cross section may consider as significant stresses unless distortion of box section is appropriately restricted. Nevertheless, during the past decades, no evaluation of distortional warping and transverse bending resistances for the multicell box section has been performed owing to geometric complexity and Insufficient information with respect to the distortion of multicell box section. The objective of present study is to evaluate the distortional warping and transverse bending resistances for the distortion of multicell box section and to validate the resistances through box girder analyses using multicell box beam element developed and conventional shell element. This developed box beam element has nine degrees of freedom per node including the effect of distortion.

• Journal of information and communication convergence engineering
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• v.16 no.1
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• pp.17-22
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• 2018

In massive multiple-input multiple-output (MIMO) systems, linear channel estimation algorithms are widely applied owing to their simple structures. However, they may cause pilot contamination, which affects the subsequent data detection performance. Therefore, herein, for an uplink multicell massive multiuser MIMO system, we consider using an alternating projection (AP) for channel estimation to eliminate the effect of pilot contamination and improve the performance of data detection in terms of the bit error rates as well. Even though the AP is nonlinear, it iteratively searches the best solution in only one dimension, and the computational complexity is thus modest. We have analyzed the mean square error with respect to the signal-to-interference ratios for both the cooperative and non-cooperative multicell scenarios. From the simulation results, we observed that the channel estimation results via the AP benefit the following signal detection more than that via the least squares for both the cooperative and non-cooperative multicell scenarios.

• Structural Engineering and Mechanics
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• v.21 no.3
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• pp.275-293
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• 2005

When a thin-walled multicell box girder is subjected to an eccentric load, the distortion becomes an important global response in addition to flexure and torsion. The three global responses appear in a combined form when a conventional shell element is used thus it is not an easy task to examine the three global responses separately. This study is to propose an analysis method using conventional shell element in which the three global responses can be separately decomposed. The force decomposition method which was designed for a single-cell box girder by Nakai and Yoo is expanded herein to multicell box girders. The eccentric load is decomposed in the expanded method into flexural, torsional, and multimode distortional forces by using the force equilibrium. From the force decomposition, the combined global responses of multicell box girders can be resolved into separate responses and the distortional response which is of primary concern herein can be obtained separately. It is shown from a series of extensive comparative studies using three box girder bridge models that the expanded method produces accurate decomposed results. Noting that the separate consideration of individual global response is of paramount importance for optimized multicell box girder design, it can be said that the proposed expanded method is extremely useful for practicing engineers.

• Environmental Mutagens and Carcinogens
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• v.17 no.1
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• pp.7-11
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• 1997

Variations in adriamycin uptake and cytotoxicity were studied in tumor cells that were grown in different growth states and microenvironments. RIF-1 tumor cells were maintained in an RPMI 1640 medium, and grown in either a monolayer or multicell spheroids. For exponentially growing cells, adriamycin cytotoxicity increased with increased dosage up to 2.5 $\mu$g/ml, and this cytotoxicity was reduced when the cells were grown in a plateau phase or in an acidic microenvironment (pH 6.6). This reduced cytotoxicity was correlated with the uptake of the drug. For multicell spheroids, the cytotoxicity of the drug was reduced dramatically, and this reduction was also correlated with a reduced uptake of the drug and an acidic pH inside of the spheroids. When the drug cytotoxicity was evaluated at different locations within the spheroids, the cells in the inner regions were least affected by the drug, suggesting that both an acidic microenvironment and noncycling plateau phase cells are contributing factors in decreasing the efficacy of the drug in an organized tissue, such as multicell spheroids.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.71-74
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• 2007

Thin-walled multicell box girders subjected to an eccentric load can be produced the three global behaviors of flexure, torsion, and distortion. But it is very difficult to evaluate each influences of major behaviors numerically. If we can decompose an eccentric load P into flexural, torsional, and distortional forces, we can execute quantitative analysis each influences of major behaviors. Decomposition of Applied Load for Thin-walled Rectangular multi-cell box girders is researched by Park, Nam-Hoi(Development of a multicell Box Beam Element Including Distortional Degrees of Freedom, 2003). But researches about thin-walled trapezoidal multi-cell section is insufficient. So, this paper deals with decomposition process and independent analysis method of multi-cell box girders include trapezoidal section.

• Journal of Communications and Networks
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• v.18 no.5
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• pp.762-772
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• 2016

This paper studies the problem of precoding and post-coding design for multicell multiuser downlink transmissions in the absence of perfect channel state information (CSI). Using statistical information of imperfect CSI, an iterative multiuser multicell transceiver design is formulated by minimizing the mean squared error (MSE) cost function of signal and leakage interference under per-base station power constraint (PBPC). The convergence of the iterative precoding and postcoding algorithm is verified by analytical and empirical results. The proposed precoding and postcoding algorithm offers a low computational complexity and robustness against CSI imperfection.

• Structural Engineering and Mechanics
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• v.61 no.3
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• pp.397-406
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• 2017

The use of fiber reinforced polymer (FRP) for torsional strengthening of reinforced concrete (RC) single cell box beams has been analyzed considerably by researchers worldwide. However, little attention has been paid to torsional strengthening of multicell box girders in terms of both experimental and numerical research. This paper reports the experimental work in an overall investigation for torsional strengthening of multicell box section RC girders with externally-bonded Carbon Fiber Reinforced Polymer CFRP strips. Numerical work was carried out using non-linear finite element modeling (FEM). Good agreement in terms of torque-twist behavior, steel and CFRP reinforcement responses, and crack patterns was achieved. The unique failure modes of all the specimens were modeled correctly as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.5
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• pp.989-991
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• 2017

This letter proposes the method for approximating a stochastic geometry based downlink multicell network performance in a wide range of interference and noise levels. This method facilitates the simplification of a multicell network design problem for the base station density and transmit power.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1140-1153
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• 2016

Since the inception of nuclear power as a commercial energy source, safety has been recognized as a prime consideration in the design, construction, operation, maintenance, and decommissioning of nuclear power plants. The release of radioactivity to the environment requires the failure of multiple safety systems and the breach of three physical barriers: fuel cladding, the reactor cooling system, and containment. In this study, nuclear reactor containment pressurization has been modeled in a large break-loss of coolant accident (LB-LOCA) by programming single-cell and multicell models in MATLAB. First, containment has been considered as a control volume (single-cell model). In addition, spray operation has been added to this model. In the second step, the single-cell model has been developed into a multicell model to consider the effects of the nodalization and spatial location of cells in the containment pressurization in comparison with the single-cell model. In the third step, the accident has been simulated using the CONTAIN 2.0 code. Finally, Bushehr nuclear power plant (BNPP) containment has been considered as a case study. The results of BNPP containment pressurization due to LB-LOCA have been compared between models, final safety analysis report, and CONTAIN code's results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6A
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• pp.779-788
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• 2008

In this present study, the three dimensional shell elements analysis method for exact distortional behavior of multicell trapezoidal box girders subjected to an eccentric loading is proposed. In order to perform the independent distortional analysis using shell elements, it is necessary to calculate exact distortional forces. In this study, the force-decomposition equation for applied eccentric load acting on multicell trapezoidal box girder is derived and the equation based on static force equilibrium and superposition theory decompose the eccentric load to the loads cause flexture, torsion and distortion. So by using this force-decomposition equation and shell element analysis, each behavior can be easily analysis independently. This independent analysis method is very useful to physically understand each major behavior of multicell box girder, especially distortional phenomenon. Furthermore, it may be also very useful for designer to perform the independent distortional analysis for diaphragm design using simple 3D shell elements model without preliminary complex calculation for distortional constants.