• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.647-653
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• 2011

In this study, a method to measure the thickness of thin film by EDS (energy dispersive spectroscopy) is suggested. We have developed a model which calculates the thickness of thin film from the characteristic x-ray intensity ratio of the elements in thin film and substrate by considering incident electron beam energy, x-ray generation curve, backscattering and absorption of x-ray, take-off angle of x-ray and tilt angle of the sample. We obtained the relation curve between the film thickness measured experimentally and the x-ray intensity ratio of elements. The film thicknesses calculated from the model agrees quite well with those measured experimentally. Therefore, the thin film thickness can be measured rapidly and accurately by using the model developed in this study and the x-ray intensity ratio obtained in EDS analysis.

• 대한기계학회논문집A
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• 제26권5호
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• pp.904-913
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• 2002

In this paper, the dynamic stress intensity factors of fracture mechanics are numerically computed in time domain using the FEM. For which the finite element formulations are derived applying the Galerkin method to the equations of motion in convolution integral as has been presented in the previous paper. To assure the strain fields of r$^{-1}$ 2/ singularity near the crack tip, the triangular quarter-point singular elements are imbedded in the finite element mesh discretized by the isoparametric quadratic quadrilateral elements. Two-dimensional problems of the elastodynamic fracture mechanics under the impact load are solved and compared with the existing numerical and analytical solutions, being shown that numerical results of good accuracy are obtained by the presented method.

• 한국지능시스템학회논문지
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• 제12권3호
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• pp.255-260
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• 2002

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-coded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete finite element(FE) model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, semi-elliptical surface cracks in a inhomogeneous plate subjected to uniform tension are solved.

• 대한기계학회논문집A
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• 제35권9호
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• pp.1091-1097
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• 2011

SGBEM-FEM 교호법은 유한 물체 내에 존재하는 삼차원 균열을 해석하는 유용한 방법으로 알려져 있다. 이 방법으로 일반적인 평면 혹은 비평면 삼차원 균열에 대한 정확한 응력강도계수를 구할 수 있다. 기존의 방법에서는 균열을 모델화 하는데 8 절점 사각형 경계요소를 사용한다. 그러나 임의 형상의 균열의 경우는 3 절점 삼각형 요소를 사용하여 균열을 모델화 하는 것이 더 편리하다. 따라서 본 논문에서는 3 절점 삼각형 요소와 7 절점 사각형 요소를 사용하여 전진 프런트 법으로 균열을 모델링 하였다. 사용된 균열 모델의 정확성을 검토하기 위하여 몇 가지 형상의 균열에 대하여 응력강도계수를 구하여 기존의 해와 비교하였다.

• 한국전기전자재료학회논문지
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• 제26권7호
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• pp.522-527
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• 2013

In this paper, We studied the change of surface and variation of elements on both electrodes of hydrogen generator of alkaline electrolysis in use of FE-SEM and SIMS. We used the stainless steel 316(600 ${\mu}m$) as electrode in condition of 25%KOH, $60^{\circ}C$ Temperature. The results show that the intensity of elements (C, Si, P, S, Ti, Cr, Mn, Fe, Ni, Mo) of Positive Electrode are decreased as much as about $10^1{\sim}10^3 $than the original electrode. Thickness of Positive Electrode is decreased about 40 ${\mu}m$ after chemical reaction. The negative electrode, however, shows a slight variation in the intensity of elements (C, Si, P, Fe, Ni, Mn, Mo) but Change of thickness and surface' shape of electrode show nothing after chemical reaction. The change in thickness and variation of Stainless Steel 316 cause the lifetime of electrode to be shorted. We also observed hydrogen, oxygen, potassium in both electrodes. Especially, The potassium is increased in proportional with depth of positive electrode. this means the concentration of alkali solutions is changed. and so we have to supply alkaline solution to generator in order to produce same quantity of hydrogen gas continuously. we hope that this study gives a foundation to develop the electrode for hydrogen generator of alkaline electrolysis.

• 한국조경학회지
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• 제21권2호
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• pp.34-49
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• 1993

This research aimed to analize the cognitive intensity of valuation(C.I.V) on urban environment as a first stage of the works on evaluative urban image under the hypothesis that it could be interpreted with a correlation analysis between the C.I.V and attitude(Satisfaction of unsatisfaction Intensity) toward urban environment. As a method of a study, 118 cognitive elements were selected representing an urban environment, and each of elements was suggested to citizens of Kyungju with 7 point Likert Scale. The analysis of C.I.V was operated under the three criteria: The first, three of urban space scale(urban scale, neighborhood scale, and housing scale), the second, four elements of urban living environment(safety, amenity, healthfulness, and effectiveness), and the last, thirteen urban unit environment(housing, traffic, education, tourism, medical/health, culture, etc.). The results were as follows: C.I.V to each of 118 elements was cleary defined, showing the possibilities of being applied to a method for subjective, or cognitive evaluation on urban environment: It was revealed that citizens'C.I.V was rather higher in non-physical, qualitative elements than in physical and quantitative ones. This shows well the limitation of the objective method of evaluation of urban environment: The results of the others' studies on the image of Kyungju based on the cognitive approach, being focused on the analysis of the visual aspects of urban structure, cultural assets, historic site and tourism, were almost same as this study but it was quite different for this research to reveal well the citizens' cognition on their living environment of traffic, education, medical, etc..

• 대한음성학회지:말소리
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• 제62호
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• pp.19-32
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• 2007

This study investigated the perception of emotional voices by transplanting some or all of the prosodic aspects, i.e. pitch, duration, and intensity, of the utterances produced with emotional voices onto those with normal voices and vice versa. Listening evaluation by 24 raters revealed that prosodic effect was greater than segmental & vocal quality effect on the preception of the emotion. The degree of influence of prosody and that of segments & vocal quality varied according to the type of emotion. As for fear, prosodic elements had far greater influence than segmental & vocal quality elements whereas segmental and vocal elements had as much effect as prosody on the perception of happy voices. Different amount of contribution to the perception of emotion was found among prosodic features with the descending order of pitch, duration and intensity. As for the length of the utterances, the perception of emotion was more effective with long utterances than with short utterances.

• Structural Engineering and Mechanics
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• 제15권5호
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• pp.563-578
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• 2003

Delaunay triangulation is combined with an adaptive finite element method for analysis of two-dimensional crack propagation problems. The content includes detailed descriptions of the proposed procedure which consists of the Delaunay triangulation algorithm and an adaptive remeshing technique. The adaptive remeshing technique generates small elements around the crack tips and large elements in the other regions. Three examples for predicting the stress intensity factors of a center cracked plate, a compact tension specimen, a single edge cracked plate under mixed-mode loading, and an example for simulating crack growth behavior in a single edge cracked plate with holes, are used to evaluate the effectiveness of the procedure. These examples demonstrate that the proposed procedure can improve solution accuracy as well as reduce total number of unknowns and computational time.

• 대한수학회논문집
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• 제12권2호
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• pp.269-273
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• 1997

We show that each element in the semigroup $S_n$ of all $n \times n$ non-singular stochastic totally positive matrices is generated by the infinitesimal elements of $S_n$, which form a cone consisting of all $n \times n$ Jacobi intensity matrices.

• 대한기계학회논문집
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• 제17권10호
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• pp.2398-2406
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• 1993

Abdi's numerical method(ref.13) for representing a stress singularity by shifting the mid-side nodes of isoparametric elements is reviewed. A simple technique to obtain the optimal position of the mid-side nodes in quadratic isoparametric finite element is presented. From this technique we can directly obtain the position of the side-nodes adjacent to the crack tip. It is also observed that the present technique provides good accuracy for the expression of the opening displacement and the determination of the mid-side nodes for more wide range of material properties than that obtained by Abdicant the finite element method is applied to determine stress intensity factors for pressurized crack perpendicular to and terminating at the interface of two bonded dissimilar materials. A proper definition for stress intensity factors of a crack perpendicular to bimaterial interface is provided. It is based upon a near-tip displacement solutions on the crack surface for interface crack between two dissimilar materials. Numerical testing is carried out with the eight-node and six-node elements. The results obtained are compared with the previous solutions.