• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.3
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• pp.111-115
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• 2006

We investigated accelerated soft error rate(ASER) in 8M static random access memory(SRAM) cells. The effects on ASER by well structure, operational voltage, and cell transistor threshold voltage are examined. The ASER decreased exponentially with respect to operational voltage. The chips with buried nwell1 layer showed lower ASER than those either with normal well structure or with buried nwell1 + buried pwell structure. The ASER decreased as the ion implantation energy onto buried nwell1 changed from 1.5 MeV to 1.0 MeV. The lower viscosity of the capping layer also revealed lower ASER value. The decrease in the threshold voltage of driver or load transistor in SRAM cells caused the increase in the transistor on-current, resulting in lower ASER value. We confirmed that in order to obtain low ASER SRAM cells, it is necessary to also the buried nwell1 structure scheme and to fabricate the cell transistors with low threshold voltage and high on-current.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.5
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• pp.313-320
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• 2016

The need for high-strength, multi-axis, and multi-functional machine tools has recently increased because of part complexity and workpiece strength. However, most of the machine tool manufacturers rely on experience for a detailed design because of the shortcomings in the existing design technology. This study uses a topology optimization method to more effectively design a large multi-functional machine tool considering static stiffness. The ram, saddle, and column parts are important structures in a machine tool. Hence, they are selected for the finite element method analysis. Based on this analysis, the optimized internal rib structure for those parts is designed for desirable rigidity and weight. This structure could possibly provide the required design technology for machine tool manufacturers.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.3
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• pp.39-49
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• 1999

The objective of this study is to characterize the landscape retaining dynamic character through the distinction between the spatial structure and the landscape. In this study, the landscape was characterized by the image of environment viewed by human being. Firstly, the landscape was disscussed in terms of such three element as the environment viewed by human being, the psychological detachment from the environment and the meaning of image. Secondly, the dynamic character of the landscape was determined by the comparision between the spatial structure of the static elements and the landscape experience through the case study Soshe garden. In the study found that landscape experience depend on the dynamic viewpoint and human views while the spatial structure is stable and static. This study also found that landscape is an open system which can be diachronically transformed by human value, while spatial structure is a synchronic closed system.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.5
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• pp.63-72
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• 2001

In this paper, to satisfy the safety and economy immediately, we assume the center of lateral load in case the dynamic motion of the torsionally unbalanced structure is transformed into the static lateral load using modal analysis and proposes a method to control the design eccentricity in order to make the center of lateral load coincide with the center of strength. And when the structure is designed by proposed method, it is shown that the structure designed by proposed method does not demand excessive additional ductility in comparison with the structure designed by provisions of other seismic building code.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1949-1957
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• 2000

All the loads in the real world act dynamically on structures. Since dynamic loads are extremely difficult to handle in analysis and design, static loads are utilized with dynamic factors. The dyna mic factors are generally determined based on experiences. Therefore, the static loads can cause problems in precise analysis and design. An analytical method based on modal analysis has been proposed for the transformation of dynamic loads into equivalent static load sets. Equivalent static load sets are calculated to generate an identical displacement field in a structure with that from dynamic loads at a certain time. The process is derived and evaluated mathematically. The method is verified through numerical tests. Various characteristics are identified to match the dynamic and the static behaviors. For example, the opposite direction of a dynamic load should be considered due to the vibration response. A dynamic bad is transformed to multiple equivalent static loads according to the number of the critical times. The places of the equivalent static load can be different from those of the dynamic load. An optimization method is defined to use the equivalent static loads. The developed optimization process has the same effect as the dynamic optimization which uses the dynamic loads directly. Standard examples are solved and the results are discussed

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.53-60
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• 1995

A multi-leg spread mooring system for floating offshore structures is important, but the multi-leg static analysis is complicated due to the nonlinear behavior of each line and the effect of current which affects each line differently. The pretensioned position of the multi-leg mooring system obtained from the static equilibrium condition changes into a different position due to external loads and current. In this paper, the new position and the static tension at each line are caculated. The relation between the initial static equilibrium position and the new position due to the external loads is expressed in terms of the Taylor's series expansion. The Runge-Kutta $4^{th}$ method is employed in analyzing the 3-dimensional static cable nonlinear equations.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.940-951
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• 2009

A comparative study on dynamic and static measurement of initial stiffness was conducted. Because soil stiffness decreases even at very small strains, the initial stiffness has been measured by dynamic tests using shear wave velocity measurement. On the other hand, due to the advance of local strain measurement, the triaxial testing device is capable of measuring the static initial stiffness. It has been known that initial stiffness measured by static triaxial tests is generally lower than that measured by dynamic tests possibly due to the limitation of static measurement of displacement at very small strains. This study presents experimental results indicating that the elastic shear moduli could be the same both in dynamic and static measurements owing to the soil anisotropy induced by anisotropic stresses.

• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.28-34
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• 2015

Armed aircraft of a basic trainer class installs external stores under wing box by using pylon and performs an operation such as weapon delivery and jettison, and should be designed to withstand all kinds of loads applied to external stores. The static strength test of pylons and wing box was performed to assess the static strength of pylon and their support structures for substantiation. Based on the test, the structures were verified to fully satisfy a given design requirement. In this paper, methods of test load generation of wing box and pylon, evaluation of test result data and design result of test set-up were presented. Comparing the FEM analysis with the same test data can lead to good match and reasonable deviation between both. Finally, based on the test and the analysis, the static strength of test article was substantiated and the reliability and effectiveness of analysis math model were obtained.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.506-513
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• 2007

One of the most widely used static mixers is Sulzer type mixer. However the structure of the element is so complicated that the mixing efficiency is better than others, whereas the pressure drop is larger than the others. Therefore new elements are necessary to reduce the pressure drop and to minimize the decrease of the mixing efficiency compared with the Sulzer ones. The objectives of this study are to develop new static mixer and to perform the experimental investigation in order to evaluate the performance of the new one, and to investigate the applicability of the one in an inline coagulant mixing system for water treatment, The pressure drops of the new static mixer elements were about 4-12% lower than that of the Sulzer SMX one, and the mixing efficiency of the Sulzer SMX one was about 2-5% higher than that of the new ones. The inline coagulant mixing system with a new static mixer element performed significantly better than the traditional mechanical mixing system for turbidity removal.

• Steel and Composite Structures
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• v.35 no.5
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• pp.641-657
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• 2020

A unique lightweight string truss deployable bridge assembled by thin-walled fiber reinforced polymer (FRP) and metal profiles was designed for emergency applications. As a new structure, investigations into the static structural performance under the serviceability limit state are desired for examining the structural integrity of the developed bridge when subjected to unsymmetrical loadings characterized by combined torsion and bending. In this study, a full-scale experimental inspection was conducted on a fabricated bridge, and the combined flexural-torsional behavior was examined in terms of displacement and strains. The experimental structure showed favorable strength and rigidity performances to function as deployable bridge under unsymmetrical loading conditions and should be designed in accordance with the stiffness criterion, the same as that under symmetrical loads. In addition, a finite element model (FEM) with a simple modeling process, which considered the multi segments of the FRP members and realistic nodal stiffness of the complex unique hybrid nodal joints, was constructed and compared against experiments, demonstrating good agreement. A FEM-based numerical analysis was thereafter performed to explore the effect of the change in elastic modulus of different FRP elements on the static deformation of the bridge. The results confirmed that the change in elastic modulus of different types of FRP element members caused remarkable differences on the bending and torsional stiffness of the hybrid bridge. The global stiffness of such a unique bridge can be significantly enhanced by redesigning the critical lower string pull bars using designable FRP profiles with high elastic modulus.