• 한국강구조학회 논문집
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• 제12권3호통권46호
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• pp.303-315
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• 2000

본 논문에서는 일반화된 21개 강성 매트릭스의 독립 변수를 모두 사용하였고 비등방성 3차원 탄성체의 지배 방정식 및 수치 해석 근사식을 유도하였다. 일반화된 3차원 해석은 2차원 해석의 제한성을 극복하는 정밀해를 보여줄 수 있으며, 두꺼운 보나 판, 또는 쉘에서 전단 변형 효과에 의한 처짐의 증가 효과를 더욱 정밀하게 해석할 수 있다. 따라서 본 논문은 3차원 비등방성 탄성체에 대하여 다양한 경계조건에 따른 유한 차분식을 유도하였으며 이를 전산화하여 해석 프로그램을 개발하였다. 특히, 본 논문에서는 자유경계조건에 대하여 개선된 유한차분법의 적용 방식을 제시하였다. 또한 탄성체의 각 방향 자유경계면에서 경계조건을 해결할 수 있는 일반화된 방식을 제시하였다. 몇가지 수치예제를 통하여 이러한 유한차분 경계처리 방식에 의한 비등방성 3차원 탄성체 해석의 타당성 및 거동을 분석하였다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제9권2호
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• pp.55-64
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• 2005

In this paper, generalized difference methods(GDM) for one-dimensional viscoelastic problems are proposed and analyzed. The new initial values are given in the generalized difference scheme, so we obtain optimal error estimates in $L^p$ and $W^{1,p}(2\;{\leq}\;p\;{\leq}\;{\infty})$ as well as some superconvergence estimates in $W^{1,p}(2\;{\leq}\;p\;{\leq}\;{\infty})$ between the GDM solution and the generalized Ritz-Volterra projection of the exact solution.

• 대한치과기공학회지
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• 제23권1호
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• pp.95-106
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• 2001

The purpose of this study was to show the method of three-dimensional morphometry developed recently and to compare the accuracy of three-dimensional morphometry with those of PA cephalometry, The three-dimensional morphometry analysis program and device were developed. Steel balls (1.2mm in diameter) were attached in twenty five landmarks of artificial human skull. This artificial human skull was used as experimental materials. From three-dimensional morphometry and PA cephalometry of artificial human skull. eleven linear measurements were acquired and made into asymmetry index. Right-left differences of measurements were used as asymmetry index. These measurements and asymmetry index were compared respectively with those of actual. The results were as follows: 1. Mean difference between three-dimensional morphometry and actual artificial human skull in linear measurements was $1.99{\pm}0.37mm$, and mean difference between PA cephalometry and actual was $21.12{\pm}0.45mm$. Both of all were reduced more than those of actual. 2. Mean difference between three-dimensional morphometry and actual artificial human skull in asymmetry index was $0.07{\pm}0.42$, and mean difference between PA cephalometry and actual was $3.63{\pm}0.60$. Three-dimensional morphometry was reduced while PA cephalometry was magnified more than that of actual. 3. Each eleven asymmetry index of three-dimensional morphometry was the same negative sign as those of actuals while only N-Z, ANS-J, Tr-Go, Tr-ANS asymmetry index were the same in PA cephalometry. These results suggest that the method of three-dimensional morphometry is more accurate than those of PA cephalometry in asymmetry analysis.

• Journal of applied mathematics & informatics
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• 제25권1_2호
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• pp.269-282
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• 2007

In this paper, we consider a two-dimensional fractional space-time diffusion equation (2DFSTDE) on a finite domain. We examine an implicit difference approximation to solve the 2DFSTDE. Stability and convergence of the method are discussed. Some numerical examples are presented to show the application of the present technique.

• 한국실내디자인학회논문집
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• 제17권4호
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• pp.84-91
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• 2008

The objective of this study is to investigate how visitors' behavior change in relation to the pattern of exhibition in art museum. For the purpose Busan Museum of Modern Art was selected as the sample in this study. And two patterns of exhibition, namely the planar exhibition and the three dimensional exhibition, were surveyed using the tracking movement method. The data gathered from random-sampling 60 visitors in a art museum was analyzed by the correlation analysis and T-test. The results are as follows; 1) There is no meaningful difference in visitors' behavior by the exhibition pattern in terms of their viewing area, viewing time, viewing distance, viewing velocity, viewing rate. 2) In contrast, there is meaningful difference in terms of the number of stops by visitors and the time spent without movement to see the objects; visitors stopped more often and stayed longer within the three dimensional exhibition space than the planar exhibition in a art museum. In sum, visitors extrinsically show no big behavioral difference between the planar exhibition and the three dimensional exhibition, but much difference in the way they communicate with objects; they show more active behavior within the three dimensional exhibition space.

• 한국운동역학회지
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• 제15권4호
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• pp.105-115
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• 2005

Recently among several tennis techniques forehand stroke has been greatly changed in the aspect of spin, grip and stance. The most fundamental factor among the three factors is the stance which consists of open, square and closed stance. The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle according to open, close, and square stance patterns during forehand stroke in tennis. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and racket head angle were defined. In conclusion, the first hypothesis, "In three dimensional maximum linear velocity of racket head would be significant difference among the stance patterns during forehand stroke in tennis" was rejected. The second hypothesis, "In three dimensional anatomical angular displacement of trunk would be significant difference among the stance patterns during forehand stroke in tennis" was rejected and the result showed that the internal-external rotation showed most important role among the three dimensional anatomical angular displacement of trunk The third hypothesis, "In three dimensional anatomical angular displacement of upperlimb would be significant difference among the stance patterns during forehand stroke in tennis" was rejected and the result showed that The three dimensional anatomical angular displacement of shoulder joint showed most important role in forehand stroke. Flexion-extension and internal-external rotation the open stance showed the largest angular displacement and is follwed by square stance and closed stance. The fourth hypothesis, "In three dimensional anatomical angular velocity of upperlimb would be significant difference among the stance patterns during forehand stroke in tennis" was rejected and the result showed that X-axis angular velocity and Z-axis angular velocity the square stance showed the largest angular velocity of the trunk and X-axis angular velocity and Y-axis angular velocity the closed stance showed the largest angular velocity of the shoulder joint.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.198-203
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• 2003

Unsteady two-dimensional nonlinear waves which are generated by the numerical wavemaker of plunging type are numerically simulated using a finite difference method in rectangular grid system. Two-dimensional Navier-Stokes equations and the continuity equation are used for the computations. Irregular leg lengths and stars are employed near the boundaries of body and free surface to satisfy the boundary conditions. Marker-density function method is adopted for the simulation of wave breaking phenomena, and the computations are carried out with various wave amplitudes and two section shapes of wavemaker. The computation results are compared with other existing computational and experimental results, and the agreement between the experimental data and the computation results is good.

• The Journal of Advanced Prosthodontics
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• 제7권6호
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• pp.460-467
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• 2015

PURPOSE. The aim of this study is to evaluate the appropriate impression technique by analyzing the superimposition of 3D digital model for evaluating accuracy of conventional impression technique and digital impression. MATERIALS AND METHODS. Twenty-four patients who had no periodontitis or temporomandibular joint disease were selected for analysis. As a reference model, digital impressions with a digital impression system were performed. As a test models, for conventional impression dual-arch and full-arch, impression techniques utilizing addition type polyvinylsiloxane for fabrication of cast were applied. 3D laser scanner is used for scanning the cast. Each 3 pairs for 25 STL datasets were imported into the inspection software. The three-dimensional differences were illustrated in a color-coded map. For three-dimensional quantitative analysis, 4 specified contact locations(buccal and lingual cusps of second premolar and molar) were established. For two-dimensional quantitative analysis, the sectioning from buccal cusp to lingual cusp of second premolar and molar were acquired depending on the tooth axis. RESULTS. In color-coded map, the biggest difference between intraoral scanning and dual-arch impression was seen (P<.05). In three-dimensional analysis, the biggest difference was seen between intraoral scanning and dual-arch impression and the smallest difference was seen between dual-arch and full-arch impression. CONCLUSION. The two- and three-dimensional deviations between intraoral scanner and dual-arch impression was bigger than full-arch and dual-arch impression (P<.05). The second premolar showed significantly bigger three-dimensional deviations than the second molar in the three-dimensional deviations (P>.05).

• 한국경영과학회지
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• 제14권1호
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• pp.108-118
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• 1989

The clustering problem for multi-dimensional entities is investigated. A heuristic method, which is named as Difference Order Clustering (DOC) is developed for the grouping of multi-dimensional entities DOC method has an advantage of identifying the bottle-neck entities. Comparisons among the proposed DOC method, modified rank order clustering (MODROC) method, and lexicographical rank order clustering using minimum spanning tree (lexico-MMSTROC) are illustrated by a part type selection problems.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.250-257
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• 2006

It is well known that Grain-oriented electrical steel sheets have two dimensional magnetic properties according to the direction of exciting field such as non-linear phase difference between magnetic flux density and magnetic field intensity vectors, different iron loss and permeability even when an alternating magnetic field is applied. The measurement and application of the two dimensional magnetic properties of the Grain-oriented electrical steel sheets, therefore, are very important for the design and precise performance analysis of electric machines made of them. As the direction of exciting field changes, in this paper, the two dimensional magnetic properties of a Grain-oriented electrical steel sheet, i.e., non-linear B-H curves, phase difference between B and H, and iron loss characteristics, are measured using SST(Single Sheet Tester) which has two axes excitation. The measured results are presented in two ways: using $(B,\theta_B)$ method and using hysteresis loops along rolling and transverse directions, respectively.