• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.215-222
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• 2010

Long and slender body, like a fuel rod, oscillating in axial flow can be unstabilized even by the small cross flow which can be activated by the flow mixer or turbulent generator. It is important to include these effects of flow disturbance in dynamic stability analysis of nuclear fuel rod. This work shows how eigen frequency of a multi-span fuel rod can be changed by the swirl flow, which is discretely generated by a flow mixer. By solving a state-space form of the eigenvalue equation for a multi-span fuel rod system, the critical velocity at which a fuel rod becomes unstable was calculated. Based on the simulation results, we evaluated how stability of a multi-spanned nuclear fuel rod with mixing vanes can be affected by the coolant flow in an operating reactor core.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.641-646
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• 2008

Long and slender body with or without flexible supports under severe operating condition can be unstabilized even by the small cross flow. Turbulent flow mixer, which actually increases thermal-hydraulic performance of the nuclear fuel by boosting turbulence, disturbs the flow field around the fuel rod and affects dynamic behavior of the nuclear fuel rods. Few studies on this problem can be found in the literature because these effects depend on the specific natures of the support and the design of the system. This work shows how the dynamics of a multi-span fuel rod can be affected by the turbulent flow, which is discretely activated by a flow mixer. By solving a state-space form of the eigenvalue equation for a multi-span fuel rod system, the critical velocity at which a fuel rod becomes unstable was established. Based on the simulation results, we evaluated how stability of a multi-spanned nuclear fuel rod with mixing vanes can be affected by the coolant flow in an operating reactor core.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.134-137
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• 1998

Caliber design in bar and rod rolling depends on the designer's experience, which in general is acquired through costly trial-and-error process. As a prerequisite for developing a scientific approach to caliber design, we present a finite element model to simulate 3-D deformation of bars and rods occurring in multi-pass sequence. The results are compared with measurements obtained from POSCO for to assess the solution accuracy. The comparison shows that the simulation results agree well experiments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.95-98
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• 1999

In this study, a method to find the optimal intermediate die geometry for the multi-stage drawing process for the rectangular rod from a round bar is proposed and a program using the proposed method is developed. On the stage of the design of the intermediate die geometry, the virtual die was constructed using the initial billet as a inlet of the drawing die and the final product as a exit of that and the virtual die was divided by the number of pass. Divided die was transformed into the rectangular one which is the intermediate die geometry for the multi-stage rectangular drawing process. In order to verify the application of the proposed method on the real industrial product, the drawing of the rectangular rod from a round which composed two stage has been performed and simulated by the three dimensional rigid plastic finite element method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.3
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• pp.251-256
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• 2011

Instead of multi-phase ac current, the magnetic field travels spatially through mechanical rotation of permanent magnets at the electrodynamic wheel (EDW). Traveling of magnetic field generally leads to a generation of inductive force in the traveling direction. In this paper, we suggest a spiral EDW to travel the magnetic field in the axial direction of the conductive rod. So, it is possible to levitate and transfer the rod through multi-axial forces by the spiral EDW. However, physical dimensions of permanent magnets constituting EDW influence relative ratios between three-axial forces generated on the rod. Therefore, the sensitivity analysis for design parameters is performed using FEM analysis. The stable operation is verified experimentally.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.05a
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• pp.358-360
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• 2004

To reduce the earth resistance, earth electrode are installed horizontally or vertically in the earth. There are two kinds of vertical earth electrode methods, one is a deep-driven rod and another is slight-driven parallel rods. Bibliography have so far analyzed the earth resistance calcalation of a rod type electrode and parallel rods type for the multi-layered earth. Befor long, We are going to study earth resistance of deep-driven rod and slight-driven parallel rods in the multi-layered earth with reference to bibliography.

• Journal of Photoscience
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• v.9 no.2
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• pp.275-277
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• 2002

We have recently found that a detergent-resistant raft like membrane (DRM) can be prepared from bovine rod outer segment membranes as a low-density buoyant fraction in sucrose density gradient ultracentrifugation. G protein (transducin) and its effector enzyme (phosphodiesterase: PDE) drastically change their affinities to DRM in the process of phototransduction. We report here that the recruitment of transducin and/or $^2$PDE to DRM has close relationship with their states in signal transduction. Active T$\alpha$/PDE-complex has a high affinity to DRM, whereas inactive transducin, or inactive PDE are excluded from DRM. Active T$\alpha$/PDE-complex seems to bind to a GTPase activating protein (GRS9) in multi- protein complexes localized on DRM. Physiological significance of the multi-protein complex on the raft-like membrane in vertebrate phototransduction would be discussed.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.348-348
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• 2001

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.49-55
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• 2022

Recently, the automobile industry has continued to demand lighter materials owing to international environmental regulations and increased convenience. To address this demand, aluminum parts have increased in popularity and are mainly developed and produced through hot forging and cold pressing. However, because this method has low yield and low production efficiency, a new manufacturing method is desirable. In this study, the water capacity efficiency of an aluminum inner tie rod socket was investigated using cold forging that provided a high yield and excellent production efficiency. Mechanical properties were derived through tensile testing of 6110A aluminum materials, and critical fracture factor and process analysis based on experimental data were carried out. The optimized process was applied as a prototype using cold multi-stage forging, and based on the derived results, the formability, productivity, and material efficiency of aluminum inner tie rod socket parts using this cold forging process was verified.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.1982-1990
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• 2022

The purpose of this study was to verify the possibility of fuel rod pattern analysis in a fresh fuel assembly using the Yonsei single-photon emission computed tomography (YSECT) system. The YSECT system consisted of three main parts: four trapezoidal-shaped bismuth germanate scintillator-based 64-channel detectors, a semiconductor-based multi-channel data acquisition system, and a rotary stage. In order to assess the performance of the prototype YSECT, tomographic images were obtained for three representative fuel rod patterns in the 6 × 6 array using two representative image-reconstruction algorithms. The fuel-rod patterns were then assessed using an in-house fuel rod pattern analysis algorithm. In the experimental results, the single-directional projection images for those three fuel-rod patterns well discriminated each fuel-rod location, showing a Gaussian-peak-shaped projection for a single 10 mm-diameter fuel rod with 12.1 mm full-width at half maximum. Finally, we successfully verified the possibility of the fuel rod pattern analysis for all three patterns of fresh fuel rods with the tomographic images obtained by the rotational YSECT system.