• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.685-688
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• 2009

Surface Texturing is very important process for high cell efficiency in crystalline silicon solar cell. Anisotropic texturing with an alkali etchant was known not to be able to produce uniform surface morphology in multi-crystalline silicon (mc-Si), because of its different etching rate with random crystal orientation. In order to reduce surface reflectance of mc-Si wafer, the general etching tendency was studied with HF/HN$O_3$/De-ionized Water acidic solution. And the surface structures of textured mc-Si in various HF/HN$O_3$ ratios were compared. The surface morphology and reflectance of textured silicon wafers were measured by FE-SEM and UVvisible spectrophotometer, respectively. We obtained average reflectance of $16{\sim}19$% for wavelength between 400 nm and 900 nm depending on different etching conditions.

• Transactions of Materials Processing
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• v.19 no.4
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• pp.224-229
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• 2010

During the multi-pass wire drawing process, wires suffer a great amount of plastic deformation that is through the cross-section. This generates tensile residual stress at surface of drawn wires. The generated residual stress on surface is one of the problems for quality of wires so that prediction and reduction of residual stresses is important to avoid unexpected fracture. Therefore, in this study, the effect of process variables such as semi-die angle, bearing length and reduction ratio on the residual stress was evaluated through Finite Element Analysis. Based on the results of the Analysis, a prediction model was established for predicting residual stress on the surface of high carbon steel(AISI1072, AISI1082). To identify the effectiveness of the proposed model, X-ray diffraction is used to measure the residual stresses on the surface. As the result of the comparison between calculated residual stresses and measured residual stresses, the model could be used to predict residual stresses in cold drawn wire.

• Transactions of Materials Processing
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• v.30 no.3
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• pp.125-133
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• 2021

In this study, response surface method (RSM), back propagation neural network (BPNN), and genetic algorithm (GA) were used for modeling and multi-objective optimization of the parameters of AA5052-H32 in incremental sheet forming (ISF). The goal of optimization is to determine the maximum forming angle and minimum surface roughness, while varying the production process parameters, such as tool diameter, tool spindle speed, step depth, and tool feed rate. A Box-Behnken experimental design (BBD) was used to develop an RSM model and BPNN model to model the variations in the forming angle and surface roughness based on variations in process parameters. Subsequently, the RSM model was used as the fitness function for multi-objective optimization of the ISF process the GA. The results showed that RSM and BPNN can be effectively used to control the forming angle and surface roughness. The optimized Pareto front produced by the GA can be utilized as a rational design guide for practical applications of AA5052 in the ISF process

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.1
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• pp.79-89
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• 2022

Soil moisture is significantly related to crop growth and plays an important role in irrigation management. To predict soil moisture, various process-based model has been developed and used in the world. Various models (Land surface model) may have different performance depending on the model parameters and structures that causes the different model output for the same modeling condition. In this study, the three land surface models (Noah Land Surface Model, Soil Water Atmosphere Plant, Community Land Model) were used to compare the model performance (soil moisture prediction) and develop the multi-model simulation. At first, the genetic algorithm was used to estimate the optimal soil parameters for each model, and the parameters were used to predict soil moisture in the study area. Then, we used the multi-model approach based on Bayesian model averaging (BMA). The results derived from this approach showed a better match to the measurements than the results from the original single land surface model. In addition, identifying the strengths and weaknesses of the single model and utilizing multi-model methods can help to increase the accuracy of soil moisture prediction.

• Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.88-95
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• 2014

Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.124-129
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• 1997

The experimental investigation is mainly focused to detect tool wear by cutting signal measurements in multi-insert face milling SS 41 and STS 304. This research have investigated the effects on the insert number, which has relationship with mean-cutting force. AE(acoustic emission) signal, tool life and surface roughness in machining SS41 and STS 304. The cutting force and AE signal are monitored to analyse the cutting process, The surface roughness of the specimens machined by TiN coated tool with the various insert numbers measured at various cutting speeds, feed rates and depths of cut, The width of flank wear is also observed.

• Journal of Sensor Science and Technology
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• v.13 no.5
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• pp.342-349
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• 2004

SK (SPR Kinds) index, which can categorize the complicated measurement methods of surface plasmon resonance by simple method, has been proposed and verified. SK index is composed of three digits, where each digit presents the type of immobilized ligand, the type of illumination and the kinds of varying parameter, sequentially. The measurement method of (33#) series among SK indices shows the possibility of the multi-sensing capability, by which the response of 2-dimensional array of immobilized ligands can be detected simultaneously. The proposed possibility of multi-sensing capability has been verified by the modeling that is based on Fresnel reflection model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.696-699
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• 2004

A side scan sonar system uses the towfish installed sonars, It is an equipment that search images of the bottom surface of the sea in real time. It is a typical equipment that is related to a sea investigation such as a geological survey, seabed communication cable and power line cable placing repair investigation, fish breeding ground investigation, sea purification, relic and mineral investigation, and mine and submarine search. It used to fined objects and investigate on the seabed surface. But, recently, it is used to sea purification and geological survey that require information of the correct surface of the seabed. So, it needs various filtering technique and image processing techniques development to acquire high resolution image. therefore, this research develops a side scan sonar using multi-beam sensors that supply various information with the fast scan speed and correct high resolution that is not a simple underwater investigation equipment.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.99-104
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• 2005

For the efficient reliability analysis, Bi-direction two-point approximation(BTPA) method is developed which solves shortcomings of conventional two-point approximation(TPA) methods that generate an approximate surface with low accuracy or sometimes do an unstable approximate surface. The conventional reliability based design optimization(RBDO) methods require high computational cost compared with the deterministic design optimization(DO) methods. To overcome the computational inefficiency of RBDO, the approximate reliability analysis approaches on the TPA surface are proposed. Using these FORM and SORM analysis strategies, multi-point aerodynamic-structure interacted shape design optimizations with uncertainty are performed very efficiently.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.1206-1212
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• 1993

In this paper, an variable structure system with an integral-augmented sliding surface is designed for the improved robust control of a uncertain multi-input multi-output(MIMO) system subject to the persistent disturbances. To effectively remove the reaching phase problems, the integral augmented sliding surface is defined, then for its design, the eigenstructure assignment technique is introduced. To guarantee the designed performance againts the persistent disturbance, the stabilizing control for multi-input system is also designed. The stability of the global system and performance robustness are investigated. The example will be given for showing the usefulness of algorithm.