• 한국세라믹학회지
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• 제31권6호
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• pp.595-600
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• 1994

Ni0.3Zn0.7Fe2O4 ferrite specimens were fabricated by dry pressing and tape casting method. The properties of each specimen were measured and compared. In order to design and manufacture the chip devices effectively, one important criterion can be that the sintered density of the laminated body should approach close to that of the dry pressed body which is regarded as standard. This requirement could be satisfied by controlling the solid loading of the ferrite sheet, lamination temperature and pressure. Using the optimum conditions (solid loading 55 wt%, lamination temperature 6$0^{\circ}C$, lamination pressure 400 kg/$\textrm{cm}^2$, sintered at 125$0^{\circ}C$ 2h) a sintered ferrite, with the density of 5.18g/㎤ and permeability of 1390 at 0.5 MHz, were obtained.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.247-252
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• 2000

Flow through turbine flow meter is simulated by solving the incompressible Navier-Stockes equations. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel Line relaxation method. The equations are solved steadily in rotating reference frames and the centrifugal force and the Coriolis force are added to the equation of motion. The standard k-$\epsilon$ model is employed to evaluate turbulent viscosity.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1145-1148
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• 2002

This paper presents a new method which is calculated to use only three vanishing points in order to compute the dimensions of object and its pose from a single image of perspective projection taken by a camera and the problem of recovering 3D models from three vanishing points of box scene. Our approach is to compute only three vanishing points without this information such as the focal length, rotation matrix, and translation from images in the case of perspective projection. We assume that the object can be modeled as a linear function of a dimension vector ν. The input of reconstruction is a set of correspondences between features in the model and features in the image. To minimize each the dimensions of the parameterized models, this reconstruction of optimization can be solved by the standard nonlinear optimization techniques with a multi-start method which generates multiple starting points for the optimizer by sampling the parameter space uniformly.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.573-578
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• 2000

Flow through turbine flow meter is simulated by solving the incompressible Navier-Stockes equations. The solution method is based on the pseudocompressibility approach and uses an implicit-upwind differencing scheme together with the Gauss-Seidel line relaxation method. The equations are solved steadily in rotating reference frames and the centrifugal force and tile Coriolis force are added to the equation of motion. The standard $k-{\varepsilon}$ model is employed to evaluate turbulent viscosity. At first the stability and accuracy of the program is verified with the flow through a square duct with a $90^{\circ}$ bend and on the flat plate.

• East Asian mathematical journal
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• 제33권1호
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• pp.1-9
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• 2017

In [8] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities, which is useful for the problem with known stress intensity factor. They consider the Poisson equations with homogeneous Dirichlet boundary condition, compute the finite element solution using standard FEM and use the extraction formula to compute the stress intensity factor, then they pose a PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor, which converges with optimal speed. From the solution they could get accurate solution just by adding the singular part. This approach works for the case when we have the reasonably accurate stress intensity factor. In this paper we consider Poisson equations defined on a domain with a concave corner with Neumann boundary conditions. First we compute the stress intensity factor using the extraction formular, then find the regular part of the solution and the solution.

• 산업경영시스템학회지
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• 제27권3호
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• pp.83-89
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• 2004

The object of this study is to survey present conditions, to analyze the development of bio-industry in northern area of Kyonggi province by the decision making method of the SWOT model, to suggest a plan for the prospect of continued development field and the location of industry, and to extract fundamental data for establishment of annual action and investment plan which can develop bio-industry. For the purpose of making a policy decision in national operation policy, business administration policy, and new product design, the research for extracting more objective and standard approach method should be continuously conducted.

• 한국대기환경학회지
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• 제13권5호
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• pp.355-360
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• 1997

The atmospheric concentration of dimethylsulfide (DMS), known as the predominant volatile organic. sulfur compound, is determined at subnanogram level by a combined application of non-cryogenic preconcentration method and gas chromatography with flame photometric detection (GC/FPD). The volatile DMS in air is preconcentrated using a trapping tube containing adsorbent like Molecular Sieve 5A (or gold-coated sands). The tube is then connected to the GC/FPD system via a six-way rotary valve, thermally desorbed at 40$0^{\circ}C$, separated on OV101 column, and detected by a flame photometric detector. The DMS peak elutes at about 2.5 mins and is integrated electronically. The analytical precision, if expressed in terms of relative standard error, is around 5%. The detection limit of our GC/FPD system is ca 1 ng of DMS. Details of our analytical system are presented.

• 환경위생공학
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• 제23권4호
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• pp.83-93
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• 2008

The non-linear least squares model(NLSM) has long been the standard technique used by hydrologists for constructing rating curves. The reasons for its adaptation are vague, and its appropriateness as a method of describing discharge measurement uncertainty has not been well investigated. It is shown in this paper that the classical method of NLSM can model only a very limited class of variance heterogeneity. Furthermore, this lack of flexibility often leads to unaccounted heteroscedasticity, resulting in dubious values for the rating curve parameters and estimated discharge. By introducing a heteroscedastic maximum likelihood model(HMLM), the variance heterogeneity is treated more generally. The maximum likelihood model stabilises the variance better than the NLSM approach, and thus is a more robust and appropriate way to fit a rating curve to a set of discharge measurements.

• Structural Engineering and Mechanics
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• 제31권5호
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• pp.481-506
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• 2009

The present study is concerned with the stochastic linear free vibration study of laminated composite plate embedded with piezoelectric layers with random material properties. The system equations are derived using higher order shear deformation theory. The lamina material properties of the laminate are modeled as basic random variables for accurate prediction of the system behavior. A $C^0$ finite element is used for spatial descretization of the laminate. First order Taylor series based mean centered perturbation technique in conjunction with finite element method is outlined for the problem. The outlined probabilistic approach is used to obtain typical numerical results, i.e., the mean and standard deviation of natural frequency. Different combinations of simply supported, clamped and free boundary conditions are considered. The effect of side to thickness ratio, aspect ratio, lamination scheme on scattering of natural frequency is studied. The results are compared with those available in literature and an independent Monte Carlo simulation.

• 대한안전경영과학회지
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• 제3권1호
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• pp.117-125
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• 2001

Polyacetal resin is usually used to make molds, but it is difficult to achieve dimension accuracy during molding. Therefore it is usually necessary to cut the polyacetal resin after a molding process. Polyacetal resin is easily machining by standard machine tool. Acetal is also a thermal stable material which can be totted without coolant Another concern about the use of polyacetal resin is that it absorbs water easily, which also results in problems with dimension accuracy Therefore, in this study, the cutting resistance of water-absorbed polyacetal resin and its surface roughness after cutting in order to achieve the highest degree of accuracy in the cutting of polyacetal resin were investigated. Also, The Robust Design method uses a mathematical tool called orthogonal arrays to study a large number of decision variables with a small number of experiments. It also uses a new measure of quality, called signal-to-noise (S/N) ratio, to predict the quality from the customer's perspective. Thus, we have taken Taguchi's parameter design approach, specifically orthogonal array, and determined the optimal levels of the selected variables through analysis of the experimental results using S/N ratio.