• Title/Summary/Keyword: 전통적 수치법

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Free Vibration Analysis of Circular Arches Considering Effects of Midsurface Extension and Rotatory Inertia Using the Method of Differential Quadrature (미분구적법을 이용 중면신장 및 회전관성의 영향을 고려한 원형아치의 고유진동해석)

  • Kang, Ki-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.9-17
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    • 2021
  • Curved beams are increasingly used in buildings, vehicles, ships, and aircraft, which has resulted in considerable effort being directed toward developing an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic circular arches has been the subject of a large number of investigations. One of the efficient procedures for the solution of ordinary differential equations or partial differential equations is the differential quadrature method DQM. This method has been applied to a large number of cases to overcome the difficulties of the complex computer algorithms, as well as excessive use of storage due to conditions of non-linear geometries, loadings, or material properties. This study uses DQM to analyze the in-plane vibration of the circular arches considering the effects of midsurface extension and rotatory inertia. Fundamental frequency parameters are calculated for the member with various parameter ratios, boundary conditions, and opening angles. The solutions from DQM are compared with exact solutions or other numerical solutions for cases in which they are available and given to analyze the effects of midsurface extension and rotatory inertia on the frequency parameters of the circular arches.

IN VITRO COMPARISON OF VARIOUS DIAGNOSTIC METHODS OF OCCLUSAL CAR10US LESIONS (교합면 우식병소의 다양한 진단법에 관한 비교연구)

  • Kim, Jae-Gon;Kim, Young-Jin;Kim, Young-Sin;Baik, Byeong-Ju
    • Journal of the korean academy of Pediatric Dentistry
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    • v.28 no.4
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    • pp.613-619
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    • 2001
  • The aims of this study were to compare the accuracy, sensitivity and specificity of cnventional visual examination, radiography and a new laser fluorescence method, KaVo Diagnodent, for the detection of occlusal caries lesions. One hundred sound human premolars and molars which had no restorations or interproximal cavities were tested by three methods. Tooth lesions depth was assessed at histologic examination using Caries detector dye The following results were obtained. 1. Diagnodent show 7.8 in sound tooth, 25.4 in initial caries, 30.5 in enamel caries, and 53.8 in dentin caries with average score 2. Spearman and Pearson relation coefficient was high between tooth-specimen test with dye and Diagnodent(0.736, 0.619), visual examination(0.664, 0.666), and was low between tooth-specimen test with dye and radiographic examination(P<0.01, total) 3. Accuracy of occlusal caries was highest on Diagnodent(65%) and lowest on radiographic examination(35%) 4. In initial caries, the sensitivity and specificity of Diagnodent method was the highest. In enamel caries, the sensitivity of visual examination was the highest and specificity of Diagnodent method was the highest. In dentinal caries, the sensitivity and specificity of Diagnodent method was the highest and sensitivity of visual examination was the lowest.

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Isogeometric Shape Design Optimization of Power Flow Problems at High Frequencies (고주파수 파워흐름 문제의 아이소-지오메트릭 형상 최적설계)

  • Yoon, Minho;Ha, Seung-Hyun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.3
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    • pp.155-162
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    • 2014
  • Using an isogeometric approach, a continuum-based shape design optimization method is developed for steady state power flow problems at high frequencies. In case the isogeometric method is employed to the shape design optimization, the NURBS basis functions used in CAD geometric modeling are directly utilized to embed the exact geometry into the computational framework so that the design parameterization for shape optimization is much easier than that in the finite element method and consequently provides the enhanced smoothness of design perturbations. Thus, exact geometric models can be used in both the response and the shape sensitivity analyses, where normal vector and curvature are continuous over the whole design space so that enhanced shape sensitivity can be expected. Through numerical examples, the developed isogeometric sensitivity is compared with finite difference one to provide excellent agreement. Also, it turns out that the proposed method works very well in the shape optimization problems.

Three Dimensional Vibration Analysis of Thick, Circular and Annular Plates with Nonlinear Thickness Variation (비선형 두께 변분을 갖는 두꺼운 원형판과 환형판의 3차원적 진동해석)

  • 장승환;심현주;강재훈
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.17 no.2
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    • pp.119-129
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    • 2004
  • A three dimensional (3D) method of analysis is presented for determining the free vibration frequencies and mode shapes of thick, circular and annular plates with nonlinear thickness variation along the radial direction. Unlike conventional plate theories, which are mathematically two dimensional (2D), the present method is based upon the 3D dynamic equations of elasticity. Displacement components u/sub s/, u/sub z/, and u/sub θ/ in the radial, thickness, and circumferential directions, respectively, are taken to be sinusoidal in time, periodic in θ, and algebraic polynomials in the s and z directions. Potential (strain) and kinetic energies of the plates are formulated, and the Ritz method is used to solve the eigenvalue problem thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four digit exactitude is demonstrated for the first five frequencies of the plates. Numerical results we presented for completely free, annular and circular plates with uniform linear, and quadratic variations in thickness. Comparisons are also made between results obtained from the present 3D and previously published thin plate (2D) data.

Moving Support Elements for Dynamic Finite Element Analysis of Statically Determinate Beams Subjected to Support Motions (지점운동을 받는 정정보의 동해석을 위한 동지점 유한요소 개발)

  • Kim, Yong-Woo;Jhung, Myung Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.37 no.4
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    • pp.555-567
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    • 2013
  • A finite element formulation for a Rayleigh-damped Bernoulli-Euler beam subjected to support motions, which accompanies quasi-static rigid-body motion, is presented by using the quasi-static decomposition method. Moving support beam elements, one of whose nodes is coincident with the moving support, are developed to represent the effect of a moving support. Statically determinate beams subjected to support motions can be modeled successfully by using moving support elements. Examples of cantilever and simply-supported beams subjected to support motions are illustrated, and the numerical results are compared with the analytical solutions. The comparison shows good agreement.

Hydroelastic Analysis of Structural Vibration in Contact with Fluid (접수구조물 진동의 유력탄성해석)

  • K.T. Chung;Y.B. Kim;H.S. Kang;J.H. Roh
    • Journal of the Society of Naval Architects of Korea
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    • v.29 no.1
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    • pp.135-142
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    • 1992
  • In the vibration analysis or submerged of floating bodies such as ship and offshore structures, the coupled system between structure and fluid satisfying the compatibility conditions on the wetted surface should be considered. It is well known that the hydroelastic analysis of structural vibration in contact with fluid can be solved by applying the finite element method to structure and the boundary element method to fluid domain. However such an approach is impractical, because fluid added mass matrix is fully coupled on whole wetted surface. To overcome this shortcoming, an efficient approach based on reanalysis scheme is proposed in this paper. The proposed method can be applied for cases with higher modes lacking 3-D reduction factor J as well as beam-like modes of marine structures. It is well known the traditional method using 2-D added mass and J-factor is good only for beam-like modes with reliable J values. The validity and the calculation efficiency of the proposed method are proved with numerical examples.

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In-Plane Extensional Buckling Analysis of Curved Beams under Uniformly Distributed Radial Loads Using DQM (등분포하중 하에서 미분구적법(DQM)을 이용한 곡선 보의 내평면 신장 좌굴해석)

  • Kang, Ki-Jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.7
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    • pp.265-274
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    • 2018
  • The increasing use of curved beams in buildings, vehicles, ships, and aircraft has prompted studies directed toward the development of an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic curved beams has been the subject of a large number of investigations. Solutions of the relevant differential equations have been obtained traditionally using standard finite difference or finite element methods. These techniques require a great deal of computer time as the number of discrete nodes becomes relatively large under the conditions of complex geometry and loading. One of the efficient procedures for the solution of partial differential equations is the method of differential quadrature. The differential quadrature method (DQM) has been applied to a large number of cases to overcome the difficulties of the complex algorithms of programming for the computer, as well as the excessive use of storage due to the conditions of complex geometry and loading. The in-plane buckling of curved beams considering the extensibility of the arch axis was analyzed under uniformly distributed radial loads using the DQM. The critical loads were calculated for the member with various parameter ratios, boundary conditions, and opening angles. The results were compared with the precise results by other methods for cases, in which they were available. The DQM, using only a limited number of grid points, provided results that agreed very well (less than 0.3%) with the exact ones. New results according to diverse variations were obtained, showing the important roles in the buckling behavior of curved beams, and can be used in comparisons with other numerical solutions or with experimental test data.

Out-of-Plane Buckling Analysis of Curved Beams Considering Rotatory Inertia Using DQM (미분구적법(DQM)을 이용 회전관성을 고려한 곡선 보의 외평면 좌굴해석)

  • Kang, Ki-jun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.10
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    • pp.300-309
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    • 2016
  • Curved beams are increasingly used in buildings, vehicles, ships, and aircraft, which has resulted in considerable effort towards developing an accurate method for analyzing the dynamic behavior of such structures. The stability behavior of elastic curved beams has been the subject of many investigations. Solutions to the relevant differential equations have traditionally been obtained by the standard finite difference or finite element methods. However, these techniques require a great deal of computer time for a large number of discrete nodes with conditions of complex geometry and loading. One efficient procedure for the solution of partial differential equations is the differential quadrature method (DQM). This method has been applied to many cases to overcome the difficulties of complex algorithms and high storage requirements for complex geometry and loading conditions. Out-of-plane buckling of curved beams with rotatory inertia were analyzed using DQM under uniformly distributed radial loads. Critical loads were calculated for the member with various parameter ratios, boundary conditions, and opening angles. The results were compared with exact results from other methods for available cases. The DQM used only a limited number of grid points and shows very good agreement with the exact results (less than 0.3% error). New results according to diverse variation are also suggested, which show important roles in the buckling behavior of curved beams and can be used for comparisons with other numerical solutions or experimental test data.

The Production of Traditional Alcoholic Beverage in Containing Medicinal Herb (한약재를 첨가한 전통주개발에 관한 연구)

  • Kim, Young-Sook;Park, Young-Sook
    • Food Science and Industry
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    • v.40 no.2
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    • pp.83-89
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    • 2007
  • 저온발효와 고온발효에 의하여 만들어진 민속주를 증류하여 알콜돗를 45%로 같이 맞추어 성분함량을 비교하였다. 발효온도에 따른 환원당의 함량을 나타내고 있으며 저온발효 민속주는 15 mg/100 mL, 고온발효 민속주는 5 mg/100 mL로 나타났다. 즉 저온 발효에서 환원당의 양이 많았으며, 그러나 시중에 판매되고 있는 소주보다는 낮은 경향을 보였다. 향기 성분에 생성과정에 영향을 주는 Fusel alcohol을 볼 때 반적으로는 발효액에 아미노산이 없는 것보다는 많을 수록 많은 양의 fusel alcohol을 생성되기는 하지만, fusel alcohol을 생성하기위한 조건은 효모의 종류, 발효조건, 발효온도, 발효액의 조성 등의 복잡한 인자가 관련된다. 본 연구에 제조한 발효주를 소주의 아미노산과 비교할 때 아미노산 함량이 전반적으로 20-100도 낮은 함량치로 나타났다. 한약재 첨가로 인하여 면역증강, 살세포 반응 억제효과, 기능성 전통주로 좋은 발효주로 인정되지만 한약재특유의 강한 향기를 약화시키는 연구가 금후에 보완되어야 한다고 본다. 발효온도에 따른 아미노산의 함량은 저온발효 조미주에서 cysteine, valine, mrthionine, isoleucine, phenylalanine이 많았으며, 고온발효 조미주에서는 serine, glycine, leucine이 많았다. 한 alanine, tyrisine, lysine은 고온발효주에는 있으나, 저온발효주에서는 나타나지 않았다. 그러나 저온발효주와 고온 발효주 모두 시중에 판매되고 있는 소주보다는 아주 낮은 경향을 보였다. 저온발효와 고온발효에 의하여 만들어진 민속주를 증류하여 알콜 도수를 45%로 같이 맞추어 성분함량을 비교하였다. 발효온도에 따른 환원당의 함량을 나타내고 있으며 저온발효 민속주는 15 mg/100 mL, 고온발효 민속주는 5 mg/100 mL로 나타났다. 즉 저온 발효에서 환원당의 양이 많았으며, 그러나 시중에 판매되고 있는 소주보다는 낮은 경향을 보였다. 아미노산 실험에서는 소주와 45% 고온 발효주를 비교 할 때 serine, glycine, cysteine, methionine, phenylalanine 등은 100배, alanine, valine, isoleucine 80배, ammonia 20배 낮은 수치를 나타냈다. OD 측정의 실험결과 또한 control과 비교시 40% 발효주에서는 10배, 45% 고은 발효주에서는 100배 낮은 측정치가 나타났으므로 한약재의 색소성분을 휘발시키는 기술이 요구된다고 본다. 항균성실험에서 항균성 측정은 06 cm paper disk agar diffusion법을 이용하였으며, 43%의 발효주와, 45% 고온 발효주가 항균력이 가장 강력한 0.95 cm의 영향을 나타냈다. 사용한 사용한 Gram 양성, Gram 음성 균주는 Escherichia coli KCCM 11591를 제외하고는 0.8 - 0.95 cm로 항균력이 강했으며, Gram negitive의 Pseudomonas aeruginosa KCTC 1750 에서는 43% 발효주에는 0.95 cm, 45% 고은 발효주에는 0.95 cm의 항균성을 나타냈으며 관능평가에서도 가장 높게 났다. 관능평가에서는 45% 고온 발효주가 가장 높게 나타났으며, 항산화성 실험에 나타난 저온 45%의 갈색도의 측정과는 항산화성에서는 좀 다른 결과를 나타낸다. 그러나 항균성이 가장 높게 나타난 43-45%와 관능평가에서 가장 높게 나타난 45% 고온 발효주를 볼 때 본 연구에서는 고온 발효주 45%가 가장 우수한 전통주로 조사되었다. 발효주를 소주의 아미노산과 비교할 때 아미노산 함량이 전반적으로 100배 정도 낮은 함량치로 나타났으므로, 한약재 첨가로 인하여 면역증강, 살세포반응 억제효과, 기능성전통주로 좋은 발효주로 인정되지만 한약재특유의 강한 향기를 약화시켜서 부드럽고 은은한 전통발효주의 연구가 금후에 보완되어야 한다고 본다.

Rediscovery of a Method for Preparation of Traditional Grape Tea (전통적인 포도차 제조방법의 재현에 관한 연구)

  • Im, Ga-Young;Jang, Se-Young;Kim, Jeong-Sook;Jeong, Yong-Jin
    • Food Science and Preservation
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    • v.17 no.1
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    • pp.66-71
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    • 2010
  • In the Joseon Dynasty, various fruit teas were popularized to promote health, with spread of Donguibogam and Hyangyag gugeupbang. As interest in fruit tea has recently increased, studies on its manufacture have become necessary. We used response surface analysis for rediscovery and commercialization of grape tea. Major materials of traditional grape tea are grape juice, pear juice, ginger juice, and honey, and the sugar contents of these materials were 12.3, 14.1, 3.3 and 75 $^{\circ}Brix$, respectively. When sensory examinations were conducted with subjects aged 40-60 years, the difference between dilution ratios of 100% and 150% was not significant, but tea diluted by 150% showed somewhat higher scores than did tea diluted by 100%. Ginger taste and sweetness were found to have the greatest effect on overall acceptance. Regression analysis on color, flavor, taste, and overall acceptance values, with reference to ginger juice and honey as independent variables, revealed that the $R^2$ values were 0.8411, 0.6717, 0.9499, and 0.9015, respectively. Contour maps were superimposed to obtain an optimal combination of ingredients for traditional grape tea, and the indicated levels of ginger juice and honey were 0.46-0.69% and 3.85-5.20%, in combination with grape juice, pear juice, and water concentrations of 28%, 9% and 60% (all w/w), respectively. Thus, it is now possible to prepare traditional grape tea.