• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1156-1166
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• 2004

Antimony profiles by MeV implantation are measured by secondary ion mass spectrometry (SIMS) and spreading resistance (SR). The moments of SIMS and simulated profiles are calculated and compared for the exact range in MeV energy. SRIM, DUPEX, ICECREM, and TSUPREM4 simulation programs are used for the calculation of range 1D, 2D. SRIM is a Monte Carlo simulation program and different inter-atomic potentials can be used for the calculation of nuclear stopping power cross-section (Sn) and range moments. Nevertheless, the range parameters were not influenced from nuclear stopping power in MeV. Through the modification of electronic stopping power cross-section (Se), the results of simulation are remarkably improved and matched very well with SIMS data. The values of electronic stopping power are optimized for Sb high energy implantation. For the electrical activation, Sb implanted samples are annealed under $N_2$ and $O_2$ ambient. Finally, Oxidation retard diffusion(ORD) effect of Sb implanted sample are demonstrated by SR measurements and ICECREM simulation.

• Tribology and Lubricants
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• v.37 no.6
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• pp.224-231
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• 2021

Recently, the waterproofing performance of high-voltage connectors in automotive vehicles has attracted increased interest. In this study, an optimal cross-sectional shape was derived to obtain uniform contact pressure and strain by considering stress relaxation problems caused by initial tension when mounting a seal. A high strain of 52.1 was distributed in the round region, owing to excessive initial tension. The finite element method (FEM) analysis indicated that the strain corresponding to the optimal initial tensile was 11. We adopted six design factors to optimize the seal cross-section and three factors as the main design factors. An orthogonal arrangement table was prepared using Minitab. FEM analyses of 16 study models were conducted to determine the optimized model. The contact pressure of the optimization model is the most evenly distributed while satisfying the waterproof performance of 0.47 MPa. Compared to the initial model, the difference in strain decreases from 35.5% to 19.6%. Finally, the derived cross-sectional shape can reduce the strain of the round region by 33.8% and the differences in the contact pressure at the upper and lower surfaces by 42% and 76%, respectively.

• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.18-23
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• 2016

A HVAC(Heating Ventilation and Air Conditioning) is adapted to increase the comfort of the cabin environment for train. The train HVAC duct system has very long duct and many outlets due to the shape of a train set. the duct cross section shape is limited by a roof structure and equipments. Therefore, the pressure distribution and flow uniformity is an important performance indicator for the duct system. In this study, the existing blow down type HVAC duct system for a train was supplemented to improve the flow uniformity by applying a design method combining design of experiment (DOE) with numerical analysis. The design variables and the test sets were selected and the performance for each test set was evaluated using CFD(Computational Fluid Dynamics). The influence of each design variable on the system performance was analysed based on the results of the performance evaluation on the test sets. Furthermore, the optimized model, whose the flow uniformity was improved was produced using the direct optimization(gradient-based method). Finally, the performance of the optimized model was evaluated using numerical analysis, and it was confirmed that its flow uniformity has indeed improved.

• Advances in aircraft and spacecraft science
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• v.7 no.4
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• pp.353-369
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• 2020

This paper presents the flutter analysis and optimum design of axially functionally graded box beam cantilever wing section by considering various geometric and material parameters. The coupled dynamic equations of the continuous model of wing system in terms of material and cross-sectional properties are formulated based on extended Hamilton's principle. By expressing the lift and pitching moment in terms of plunge and pitch displacements, the resultant two continuous equations are simplified using Galerkin's reduced order model. The flutter velocity is predicted from the solution of resultant damped eigenvalue problem. Parametric studies are conducted to know the effects of geometric factors such as taper ratio, thickness, sweep angle as well as material volume fractions and functional grading index on the flutter velocity. A generalized surrogate model is constructed by training the radial basis function network with the parametric data. The optimized material and geometric parameters of the section are predicted by solving the constrained optimal problem using firefly metaheuristics algorithm that employs the developed surrogate model for the function evaluations. The trapezoidal hollow box beam section design with axial functional grading concept is illustrated with combination of aluminium alloy and aluminium with silicon carbide particulates. A good improvement in flutter velocity is noticed by the optimization.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.2
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• pp.41-55
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• 2005

In an effort to preserve biodiversity in increasingly fragmented green patches, Korea has been installing eco-corridors over or under some arterial or expressways. In a survey of 43 such eco-corridors installed up until the year 2003, some problems and issues were identified. Some selected overseas eco-corridors were also investigated to find implications for the improvements of future installations in Korea. Major findings are; - For most existing eco-corridors, target species are not specified and locations of the eco-corridors are not well considered, and consequently it is questionable if wildlifes are crossing them - Most of existing eco-corridors lack supporting facilities such as fences that guide wildlife to cross them and prevent them from running into the road - Planting on the eco-corridors is not sufficient, not diverse enough in species, and not very considerate of wildlife but designed and planted in a similar manner as in urban parks - Where target species are not well specified, the location, width, cross section, and other aspects of the eco-corridors can not be optimized - It is suggested that eco-corridors are planned at early stages of road planning so that the number and locations of eco-corridor(s) decided as necessary and even the alignment and design of roads consider the installation of eco-corridors in advance - Monitoring of wildlife crossings is needed for improved eco-corridor planning and design - Nationwide green network plan is desirable to be made first and eco-corridors fit into it.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.3
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• pp.367-372
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• 2018

The objective of this paper is to optimize the cross-section of aluminum decking units used in the bass boats under operating conditions, and to verify the optimized model from the results via by ANSYS software. Aluminum decking unit is needed to endure specific loading while leisure activity and sailing. For a stiffer and more cost-neutral aluminum decking unit, optimization is often considered in the naval and marine industries. This optimization of the aluminum decking unit is performed using the ANSYS program, which is based on the topology optimization method. The generation of finite element models and stress evaluations are conducted using the ANSYS Multiphysics module, which is based on the Finite Element Method (FEM). Through such a series of studies, it was possible to determine the most suitable case for satisfying the structural strength found among the phase-optimized aluminum deck units in bass boats. From these optimization results, CASE 1 shows the best solution in comparison with the other cases for this optimization. By linking the topology optimization with the structural strength analysis, the optimal solution can be found in a relatively short amount of time, and these procedures are expected to be applicable to many fields of engineering.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.109-118
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• 1994

In this study, an optimization method to design the hull structure of the surface effect ships with twin hulls is proposed for the purpose of minimization of weight based on the regulations of DnV class, and computer programs following the method are developed. The method uses simple formulas as to bending and buckling strength of beams and plates to design local structures, and considers the effect of interaction between longitudinal girders and transverse web frames by grillage analysis and calculates torsional strength of the cross structure by the simplified method. Global optimization of the midship section is attained by integration of optimized substructures. According to optimized results by applying the method to the designed ship, reduction of 20 percent of hull weight can be shown, and optimum transverse frame space can be obtained.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3291-3300
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• 2023

Recently molybdenum alloys have been introduced as accident tolerating materials for cladding of fuel rods. Molybdenum element has seven stable isotopes with different neutron absorption cross section used in various fields, including nuclear physics and radioisotope production. This study presents separation approaches for all intermediate isotopes of molybdenum element by squared-off cascades using a newly developed numerical code with Salp Swarm Algorithm (SSA) optimization algorithm. The parameters of cascade including feed flow rate, feed entry stage, cascade cut, input feed flow rate to gas centrifuges (GCs), and cut of the first stage are optimized to maximize both isotope recovery and cascade capacity. The squared off and squared cascades are studied, and the efficiencies are compared. The results obtained from the optimization showed that for the selected squared off cascade, Mo⁹⁴ in four separation steps, Mo⁹⁵ in five steps, Mo⁹⁶ in six steps, Mo⁹⁷ in seven steps, and Mo⁹⁸ in two steps are separated to the desired concentrations. The highest recovery factor is obtained 63% for Mo⁹⁴ separation and lowest recovery factor is found 45% for Mo⁹⁵.

• Journal of ILASS-Korea
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• v.16 no.2
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• pp.90-96
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• 2011

Atomized liquid jets from the washing nozzle which configured with recirculation chamber for cleaning hot-zone area are accelerated and impinged on the head lamp surface. Cleaning efficiency of head lamp can be increased with injecting washing fluids into the hot-zone area. Experimental and numerical studies with various design parameters were executed to reveal the relations between internal geometry and internal flow in the washing nozzle. Spray structures were fitted with each of the head lamp surfaces and spray nozzles were optimized to the spray pattern. The recirculation chamber induces a recirculation flow and can be decreased the pressures perturbation inside the chamber. Orifice determines the mass flow rate. When the diameter of orifice is excessively large, it showed an unstable spray pattern. As a nozzle exit angle increases, density distributions are separated with two section. Also, as a protrusion length of nozzle exit increases, spray patterns are spread into a large area and density distributions showed unstable trend.

• Advances in concrete construction
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• v.1 no.1
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• pp.1-27
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• 2013

Discrete steel fibres can increase significantly the bending and the shear resistance of concrete structural elements when Steel Fibre Reinforced Concrete (SFRC) is designed in such a way that fibre reinforcing mechanisms are optimized. To assess the fibre reinforcement effectiveness in shallow structural elements failing in bending and in shear, experimental and numerical research were performed. Uniaxial compression and bending tests were executed to derive the constitutive laws of the developed SFRC. Using a cross-section layered model and the material constitutive laws, the deformational behaviour of structural elements failing in bending was predicted from the moment-curvature relationship of the representative cross sections. To evaluate the influence of the percentage of fibres on the shear resistance of shallow structures, three point bending tests with shallow beams were performed. The applicability of the formulation proposed by RILEM TC 162-TDF for the prediction of the shear resistance of SFRC elements was evaluated. Inverse analysis was adopted to determine indirectly the values of the fracture mode I parameters of the developed SFRC. With these values, and using a softening diagram for modelling the crack shear softening behaviour, the response of the SFRC beams failing in shear was predicted.