• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4431-4446
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• 2023

A Multiphysics coupling framework, MPCORE, has been developed to analyze safety parameters using the best estimate codes. The framework contains neutron kinetics (NK), thermal hydraulics (TH), and fuel performance (FP) codes to analyze fuel burnup, radial power distribution, and coolant temperature (T_bc). Shuffling and rotation capabilities have been verified on the Watts Bar reactor for three cycles. This study focuses on two coupling approaches for TH and FP modules. The one-way coupling approach involves coupling the FP code with the NK code, providing no data to the TH modules but getting T_bc as boundary condition from TH module. The two-way coupling approach exchanges information from FP to TH modules, so that the simplified heat conduction solver of the TH module is not used. The power profile in both approaches does not differ significantly, but there is an impact on coolant and cladding parameters. The one-way coupling approach tends to over-predict the cladding hydrogen concentration (CHC). This research highlights the difference between one-way and two-way coupling on critical boron concentration, T_bc, CHC, oxide surface temperature, and pellet centerline temperature. Overall, MPCORE framework with two-way coupling provides a more accurate and reliable analysis of safety parameters for nuclear reactors.

• Journal of the Korean Ceramic Society
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• v.30 no.2
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• pp.131-138
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• 1993

The effects of silane coupling agents on the injection molding process were investigated using silicone nitride mixtrues with a binder system containing polypropylene as a major binder (55vol% solid loading). The formation of bonding between silicon nitride powder and coupling agents was confirmed through the analyses of powder surface. The use of coupling agents improved mixing characteristics judged by the torque change during mixing process. the coupling agents also reduced molten viscosity of the mixture considerably, which is a main factor to determine the flow of the mixture. However, the bonding between coupling agents and polymers had a negative effect on the debinding process by retarding the thermal decomposition.

• Journal of the Korean Mathematical Society
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• v.43 no.3
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• pp.659-676
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• 2006

In this paper, we consider three-component reaction-diffusion system. With an integral condition and a global coupling, this system gives us an interesting free boundary problem. We shall examine the occurrence of a Hopf bifurcation and the stability of solutions as the global coupling constant varies. The main result is that a Hopf bifurcation occurs for global coupling and this motion is transferred to the stable motion for strong global coupling.

• Journal of the Earthquake Engineering Society of Korea
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• v.18 no.3
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• pp.117-124
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• 2014

Diagonal reinforced coupling beam of coupled shear walls can provide sufficient strength and stiffness to resist lateral force. However, the reinforcement details for coupling beams required by ACI 318 (2011) are difficult to construct because of the reinforcement congestion and confined interior area. This study presents experimental results about the seismic performance of coupling beams having bundled diagonal reinforcement to improve the workability. Experiments were conducted using half scaled precast coupling beams having an aspect ratio of 2.0. It was observed that the bundled diagonal reinforced coupling beams can develop seismic performance similar to the coupling beams with requirement details specified in ACI 318 (2011).

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.149-151
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• 2015

Coupling with a ring of capacitors introduces in-phase coupling current in multi-stage LC oscillators, increasing coupling strength and phase spacing accuracy. Capacitive coupling is effective at high-frequency applications because it increases coupling strength with the operating frequency. However, capacitive loading from the ring lowers operating frequency and reduces the tuning range. Mathematical expressions of phase noise and phase spacing accuracy with capacitive coupling are examined here, and transistor-level simulations confirm the effectiveness of the capacitive coupling.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.8
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• pp.99-109
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• 1992

First, the coupling faults of semiconductor memory are classified in detail. The chained coupling fault is introduced and defined, which results from sequential influencing of the coupling effects among memory cells, and its mapping relation is described. The linked coupling fault and its order are defined. Second, the deterministic “Algorithm GA” is proposed, which detects stuack-at faults, transition faults, address decoder faults, unlinked 2-coupling faults, and unlinked chained coupling faults. The time complexity and the fault coverage are improved in this algorithm. Third, it is proved that the march test of an address sequence can detect 97.796% of the linked 2-coupling faults with order 2. The deterministic “Algorithm NA” proposed can detect to the limit. The time complexity and the fault coverage are improved in this algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.857-863
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• 2003

In rotating machinery, unbalance and misalignment are major concerns in vibration. Unbalance can be eliminated by balancing procedure to some degree. but little work has been done on the vibrations that occur in a misaligned rotor system. Currently, no generalized theoretical model based on a rotor system with flexible coupling is available to describe the vibrations caused by misalignment. As a part of systematic investigation on the misalignment, first of all, the study on flexible coupling with misalignment should be preceded. In this study, the geometry and reaction force and moment of a gear coupling with misalignment was investigated, also the theoretical model of a gear coupling with misalignment was presented by using the relationship between geometry and moment of gear coupling. It is expected that the proposed procedure can be applied to derive the theoretical model of other couplings.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.61-64
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• 2006

A common form of construction for apartment buildings consists of walls and coupling element. But, the structural behavior of coupling element are very complex and affected by the properties of coupling element. The propose of this paper is to evaluation the behavior of coupling element in wall-dominant system. An 1/2 scale three specimens was constructed and under cyclic loads. The specimen was consisted of opening walls and coupling element as well as floor slabs. From the result of this study, in coupling slabs, the stresses were not uniform across the width. And the effective width of coupling slabs was found smaller than the that of predicted from previous studies.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.83-91
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• 2002

A common form of construction for apartment buildings consists of walls and coupling elements. But, the structural behavior of coupling elements are very complex and affected by the properties of coupling elements. The objective of this study is to estimate the behavior of coupling elements in wall-dominant systems. For the purpose of this study, two wall-slab specimens and two wall-beam specimens were tested. The specimens with different reinforcement layouts were subjected to reversed cyclic loading, consistent with coupling action, with increasing imposed inelastic deformations. From the results of this study, 1) in coupling slabs, the stresses were not uniform across the width, 2) the effective width of coupling slabs was found smaller than that of predicted from previous studies, 3) diagonally reinforced coupling beam with slab showed larger ductility and more amount of energy dissipation to be attained compared with conventionally reinforced coupling beam.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.1
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• pp.21-30
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• 1998

The effects of GABA and glutamate on the horizontal cells were explored by an intracellular recording method to discern the mechanisms of receptive field formation by chemical coupling in the catfish outer retina. The results suggest that the horizontal cells of the catfish retina might use GABA as their transmitters and that the GABAergic system contributes to the formation of receptive fields of the horizontal cells. GABAC receptors may be involved in a chemical coupling between horizontal cells and concerned with the depolarizing actions by GABA on horizontal cells in the catfish retina. Since the chloride equilibrium potential is more positive than the dark membrane potential in horizontal cells, GABA released from a horizontal cell may depolarize the neighboring horizontal cells. Thus a chemical coupling between horizontal cells may be formed. $GABA_A$ receptors also may be involved in the negative feedback mechanism between photoreceptor and horizontal cell. And glutamate may be involved in connecting positive and negative feedback systems since it potentiated the GABA's actions. Therefore, it is presumed that large receptive fields in the catfish retina are formed not only by electrical coupling but also by chemical coupling between horizontal cells. And information travels laterally by pathways involving both electrical coupling composed of gap junctions and chemical coupling in the retinal network.