• International Journal of CAD/CAM
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• 제4권1호
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• pp.33-45
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• 2004

In this work, a rational procedure has been formulated for the selection of points approximating slice contours cut in LOM (Laminated Object manufacturing) with first order approximation. It is suggested that the number of points representing a slice contour can be 'minimised' or 'optmised' by equating the horizontal chordal deviation (HCD) to the user-defined surface form tolerance. It has been shown that such optimization leads to substantial reduction in slice height calculations and NC codes file size for cutting out the slices. Due to optimization, the number of contour points varies from layer to layer, so that points on successive layer contours have to be matched by four sided ruled surface patches and triangular patches. The technological problems associated with the cutting out of triangular patches have been addressed. A robust algorithm has been developed for the determination of slice height for optimum and arbitrary numbers of contour points with different strategies for error calculations. It has been shown that optimisation may even lead to detection and appropriate representation of elusive surface features. An index of optimisation has been defined and calculations of the same have been tabulated.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.846-851
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• 2017

Piezoelectricity is the capability of a piezoelectric material to change mechanical energy into electrical energy. The determination of electrical and mechanical properties plays a significant role in characterizing the piezoelectric material. The energy losses characteristics of piezoelectric material can be described by mechanical quality factor. In this paper, the output voltage and mechanical quality factor of Lead Zirconate Titanate (PZT-4A) piezoelectric material is determined under various resistance and loading conditions by using the test setup. The commercial FEM software ABAQUS is used to analyze the performance of piezoelectric material under static loading conditions. It is observed that these properties affect the performance of a material particularly in the designing of smart structures. The experimental results are partially compared to the simulation values.

• Structural Engineering and Mechanics
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• 제67권5호
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• pp.439-455
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• 2018

Within a probabilistic framework, this paper addresses the determination of the static structural response of beams and frames with partially restrained (semi-rigid) connections. The flexibility of the nodal connections is incorporated via an idealized linear-elastic behavior of the beam constraints through the use of rotational springs, which are here considered uncertain for taking into account the largely scattered results observed in experimental findings. The analysis is conducted via the Probabilistic Transformation Method, by modelling the spring stiffness terms (or equivalently, the fixity factors of the beam) as uniformly distributed random variables. The limit values of the Eurocode 3 fixity factors for steel semi-rigid connections are assumed. The exact probability density function of a few indicators of the structural response is derived and discussed in order to identify to what extent the uncertainty of the beam constraints affects the resulting beam response. Some design considerations arise which point out the paramount importance of probability-based approaches whenever a comprehensive experimental background regarding the stiffness of the beam connection is lacking, for example in steel frames with semi-rigid connections or in precast reinforced concrete framed structures. Indeed, it is demonstrated that resorting to deterministic approaches may lead to misleading (and in some cases non-conservative) outcomes from a design viewpoint.

• 대한기계학회논문집A
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• 제24권4호
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• pp.1024-1031
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• 2000

The plate waves propagating in thin plates have dispersive nature showing the dependence of velocities on the frequency. Wavelet transform (WT) using Gabor function can be used to analyze the dispersive waves in the time-frequency domain, and then to find the arrival time of the waves propagating in the plate. Plate waves in the aluminum plate of 3 mm thickness were identified and generated by pencil lead breaks and the lowest order symmetric ($S_o$) and antisymmetric ($A_o$) modes were analyzed by the WT method. The measured group velocities agreed very well with theoretical predictions in the frequency range of 50-400 kHz. The pencil breaks were also used to simulate acoustic emission sources in the plate, and the source location algorithm using the wavelet transform of dispersive plate waves was found to give accurate results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.881-887
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• 2005

A total knee replacement is an extremely 'position-sensitive' operation; a malposition or a malalignment of the components will lead to a breakage of the component, a fracture around the knee prosthesis, and the limitation of range of the motion, etc. In a conventional total knee replacement, surgeons have to select an appropriate prosthesis according to the shape of the surgical region. A wrong selection may give rise to side effects or to need re-operation. Nevertheless, it is so difficult to choose the most proper prosthesis out of various kinds of prosthesis. This paper presents a surgical planning system for the total knee replacement with an operation simulating method in order to determine the parameters for the total knee replacement operation. We select an alignment axis and a resection angle as major operation parameters in the total knee replacement operation, and introduce the method to determine the major operation parameters with the operation simulator we developed. The simulator is used to determine operation parameters for optimized operations, to select the most appropriate prosthesis, and to analyze the prospective problems of the operation.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2001년도 NIR-2001
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• pp.1518-1518
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• 2001

In the area of the destruction-free NIR analysis of fruit and vegetables development has not yet progressed as far as in grain and similar products. One reason for that is, that in contrast to grains, in fruit and vegetables water appears as the outstanding main-component making up typically 80% by weight of the fruit. Of the M absorption spectrum of pure water the bands at 1450, 970 and 760 nm are the first, second and third overtones respectively of O-H stretch while those at 1940 and 1190 are combination bands involving O-H stretch and O-H bend. The choice of band for spectrometry is governed by considerations of sensitivity and selectivity. The overtone bands are satisfactory for use in moisture measurements from 0 to 4 % depending on path length. Measurements in fruits and vegetables at wavelength areas that are also important for the determination of carbohydrates (sucrose, glucose, fructose) often lead to total absorption in the presence of significant water even if short path lengths are possible. In this work model systems are used containing different carbohydrates in solvents like heavy water (D$_2$O) or dimethylsulfoxide (DMSO) that do not contain O-H functional groups.

• Industrial Engineering and Management Systems
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• 제6권2호
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• pp.136-145
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• 2007

The selection of suppliers and the determination of order quantities to be placed with those suppliers are important decisions in a supply chain. In this research, a non-linear mixed integer programming model is presented to select suppliers and determine the order quantities. The model considers the purchasing cost which takes into account quantity discount, the cost of transportation, the fixed cost for establishing suppliers, the cost for holding inventory, and the cost of receiving poor quality parts. The capacity constraints for suppliers, quality and lead-time requirements for the parts are also taken into account in the model. Since the purchasing cost, which is a decreasing step function of order quantities, introduces discontinuities to the non-linear objective function, it is not easy to employ traditional optimization methods. Thus, a heuristic algorithm, called particle swarm optimization (PSO), is used to find the (near) optimal solution. However, PSO usually generates initial solutions randomly. To improve the PSO solution quality, a heuristic procedure is proposed to find an initial solution based on the average unit cost including transportation, purchasing, inventory, and poor quality part cost. The results show that PSO with the proposed initial solution heuristic provides better solutions than those with PSO algorithm only.

• Journal of Yeungnam Medical Science
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• 제3권1호
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• pp.1-11
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• 1986

As public awareness of the various warning signs of malignancy increases, so does the concern evoked by the self identified finding of mass in the head and neck area. Not all the palpable masses are always significantly abnormal, but any nontender mass especially to the adult is significant enough to warrent further full investigation and follow up, the object of which should be to determine the possibility of malignancy and urgency of treatment. Approach to the diagnosis of the neck mass is so important in that it affects decision regarding further evaluation would lead to the determination of the most efficacious mode of therapy, eventually to the good prognosis. So, it should be emphasized that approach to the diagnosis of neck mass should be planned, systematic and thorough, this begins with the taking careful history following performance of complete examination of the head and neck especially to the nasopharynx, tongue base, pyriform sinus, palatine tonsil and larynx. Then a number of laboratory and radiologic studies are available, following triple endoscopy under general anesthesia and blind biopsy if needed. The most important rule to keep is that any biopsy procedures should be delayed to the last modality of effort to the diagnosis and if it should be done, under the plan of radical neck dissection.

• 한국대기환경학회지
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• 제26권1호
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• pp.77-84
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• 2010

The diffusion and partition coefficients of polyurethane foam (PUF) are estimated using a microbalance experiment and small chamber test. The microbalance is used to measure sorption/desorption kinetics and equilibrium data. When the diffusion condition is controlled in the chamber of the sample, interactions between volatile organic compounds (VOCs) and PUF can lead to the estimation of a relatively homogenous rate of mass transfer in the interiors and surfaces of PUF. The estimates of the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) are shown to be independent of the concentrations of VOCs. This approach, if applied to a diffusion-controlled or physically-based model, can facilitate more precise prediction of their source/sink behavior. Although further research and more rigorous validation is needed, an emission model applied with the diffusion and partition coefficients from this research holds promise for the improvement of reliability in predicting the behavior of VOCs emitted from porous building materials by D and K.

• 대한조선학회논문집
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• 제54권1호
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• pp.63-70
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• 2017

Release of hazardous and flammable gas is a significant contributor to risk. The ignition of flammable gas clouds can lead to explosion accidents in the offshore installations. A gas detector, which is one of active protect systems, brings the module into a safe state through emergency shut down processes and reduces the damage by eliminating the dangerous releases. It is critical to understand the gas release, the wind field, and the complex geometry of installations to determine gas detector placement. In this paper, the Gas detector Location Index (GLI) which is a novel index for optimal detector location determination to efficiently prevent explosion accident using probabilistic approach.