• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1653-1661
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• 2012

In this study, the pressure drop changes and structural characteristics of a SMART rod bundle under the effect of a coolant were investigated. The turbulence model of the BSL Reynolds stress model was used to model the coolant flow, and a fluid solid interaction simulation was conducted. First, fuel rod vibration analysis was performed to confirm the natural frequency of the fuel rod, which was supported by spacer grid assemblies, and this was compared with experimental results. From the experimental results, the natural frequency was found to be 48 Hz, and the error compared with the simulation results was 2%. The pressure drop at the rod bundle was calculated and compared with the experimental data; it showed an error of 8%, demonstrating the simulation accuracy. In the flow analysis, the flow velocity and secondary flow at different domains were calculated, and vortex generation was also observed. Finally, through the fluid solid interaction analysis, the fuel rod displacements caused by flow-induced vibrations were calculated. Then, calculated displacement PSD at maximum displacement happed point.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4717-4722
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• 2014

In shipyards, a large number of dog-pieces are used to align welding joints and prevent welding deformation in the block assembly stage. The huge working man-hours consumed in the working process of dog-pieces impedes the productivity growth of shipyards. In this study, an analysis method based on the experimental results was proposed to simulate the welding deformation of butt joints with a dog-piece setting. The simulation of welding deformation of a hull block joint was performed using the proposed analysis method. Finally, the proposed analysis method can be used to establish guidelines for the proper use of dog- pieces in the block assembly stage.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.3
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• pp.186-193
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• 2018

Modern manufacturing industries is to produce both precise and robust mechanical parts without failure while they are in service. In order to prevent a part failure for its lifetime, a mechanical design for a part should be examined on a basis of mechanical simulation. A nozzle plate, being a key part in steam engines, changes flow directions of steam in a turbine used in power plant. This paper is to the design and test for part safety and durability. Currently, nozzle plates are fabricated by welding nozzles to their plates. Welding causes some defects on the used materials while they are being manufactured. Another major defect is un-even pitches between welded nozzles. Welding causes phase changes because of high melting temperature of metal. This leads to decay on the welding spots, which weakens their structural strength and then, may lead to early damages on mechanical structures. This research proposes assembly-typed nozzle plate without welding. From the beginning, nozzle and plate are designed for insertion-typed assembly. Nozzle head and foot are designed in accordance with the grooves on outer ring and inner ring of a plate to make mating surfaces. Then the nozzle plate should be proved for structural and fatigue safety before they are put in manufacturing. This research adopts commercial softwares for modeling and mechanical simulation. The test result shows that the design with smaller mating area and deeper insertion produces higher safety in terms of structure and durability. From the conclusion, this paper proposes the assembly-typed nozzle plate to replace the welding typed.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.57-64
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• 2021

The domestic semiconductor industry can produce various products that will satisfy customer needs by diversifying assembly parts and increasing compatibility between them. It is necessary to improve the production line as a method to reduce the work-in-process inventory (WIP) in the assembly line, the idle time of the worker, and the idle time of the process. The improvement of the production line is to balance the capabilities of each process as a whole, and to determine the timing of product input or the order of the work process so that the time required between each process is balanced. The purpose of this study is to find the optimal WIP and buffer size through SA (Simulated Annealing) that minimizes lead time while matching the number of two parts in a parallel assembly line with bottleneck process. The WIP level and buffer size obtained by the SA algorithm were applied to the CONWIP and DBR systems, which are the existing production systems, and the simulation was performed by applying them to the new hybrid production system. Here, the Hybrid method is a combination of CONWIP and DBR methods, and it is a production system created by setting new rules. As a result of the Simulation, the result values were derived based on three criteria: lead time, production volume, and work-in-process inventory. Finally, the effect of the hybrid production method was verified through comparative analysis of the result values.

• Journal of the Korea Society for Simulation
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• v.22 no.4
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• pp.83-92
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• 2013

The demand of a camera-lens-module which is installed in mobile phone has been increased explosively as the increase of mobile phone market. Recently, two missions are given to the parts manufacturer of lens module, and they are how to keep the quality of injection moulding process as the increase of resolution, and how to decrease manufacturing cost. In this paper, a simulation study is introduced which is used for developing barrel and shield considering the double-cassette type of mould. At first, the simulation for injection process using Mold Flow$^{TM}$ is applied in the phase of mould design, and mechanical simulation using DPM Assembly$^{TM}$ is applied for collision detection between picking robot and mould. As a result, the productivity increased more than 300%.

• Journal of Welding and Joining
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• v.22 no.6
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• pp.25-29
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• 2004

Some industrial steel structures are composed by components linked by several welding joints to constitute an assembly. The main interest of assembly simulation is to evaluate the global distortion of welded structure. The general method, thermo-elasto-plastic analysis, leads to excessive model size and computation time. In this study, a simplified method called "Local and Global approach" was developed to break down this limit and to provide a accurate solution for distortion. Local and global approach is composed of 3 steps; 1) Local simulation of each welding joint on a dedicated mesh (usually very fine due to high thermal gradients), taking into account for the non linearity of the material properties and the moving heat source. 2) Transfer to the global model of the effects of the welding joints by projection of the plastic strain tensors. 3) Elastic simulation to determine final distortions in global model. The welding deformation test for mock-up structure was performed to verify this approach. The predicted welding distortion by this approach had a good agreement with experiment results.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.4
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• pp.545-548
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• 2017

This study describes the design and implementation of IFA(Input Filter Assembly) for Digital Satellite Communication. The IFA unit for SHF band consists of coupler, LPF(Low Pass Filter) and input Filter. Through the pre-simulation analysis of space environment, the possibility of the malfunction of equipment minimized and we designed a reliable IFA through simulation for vibration analysis generated during the launch, and compared pre-simulation of main performance results to test results about main performances of IFA after production.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.9-19
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• 2014

The automotive industry has made much efforts to deliver finished vehicles to customers with speed and reliability. Decreasing the time a vehicle stays within an assembly plant from production release to shipment contributes to reduce the total order lead-time and consequently, the total transportation cost as well. Conventional shipment planning algorithms are limited in accommodating the dynamics of assembly plant operations as to finished vehicle shipment. This paper presents a market-based multi-agent shipment planning algorithm to optimize the performance of vehicle shipment process, capturing the operationally disruptive events. Experimental results using simulation show that the algorithm improves vehicle shipment performance with respect to lead time, labor efficiency, finished product quality, and transportation efficiency.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.254-260
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• 2000

The spacer grid is one of the main structural components in fuel assembly, which supports the fuel rods, guides cooling water, and protects the fuel assembly from the external impact load such as earthquakes. The nonlinear dynamic impact analysis is conducted by using the finite element code ABAQUS/Explicit. Boundary condition for dynamic analysis is well applied to the test condition. Simulation results also similarly predict the local buckling phenomena. In addition to the buckling parameter, the local buckling cause is examined by both simulation and test method. It is found to correspond well with the test results. Impact tests are also carried out for some specimens of the spacer grid in order to compare the results between the test and the simulation. This test is accomplished by a free fall dummy weight onto the specimen. From this test, only the uppermost and lowermost layers of the multi-cell are buckled, which implies the local buckling at the weakest point of the grid structure.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.30-35
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• 2004

The HANARO, a multi-purpose research reactor of 30 MWth open-tank-in-pool type, has been under normal operation since its initial criticality in February, 1995. Many experiments should be safely performed to activate the utilization of the HANARO. HANARO flow simulation facility is being developed for the endurance test of reactivity control units for extended life time and the verification of structural integrity of those experimental equipments prior to loading in the HANARO. This facility is composed of three major parts; a half-core structure assembly, a flow circulation system and a support system. The flow circulation system is composed of a circulation pump, a core flow piping, a core bypass flow piping and instruments. The system is to be filled with de-mineralized water and the flow should be met the design requirements to simulate a similar flow characteristics in the core channel of the half-core structure assembly to the HANARO. This paper, therefore, presents an analytical analysis to study the flow behavior of the system. Computational flow analysis has been performed for the verification of system pressure variation through the three-dimensional analysis program with the standard $k-{\epsilon}$ turbulence model and for the verification of the structural piping integrity through the finite element method. According to the analysis results, it could be said that the design requirements and the structural piping integrity of the flow circulation system are satisfied.