• 물과 미래
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• 제24권4호
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• pp.85-91
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• 1991

전국에 산재해있는 20개 하천유역을 선정하여 월강우량과 유출량 자료를 사용하여 Rosenbrock의 Rotating Coordinate Search Method에 의해 Thomas abcd 모형의 변수를 결정하였다. 결정된 4개 변수와 2개 초기조건 변수는 유역의 기상인자, 지형인자 및 지질특성인자와 다종상관관계로 표시하였다. 이와 같이 구성된 Thomas 형의 월유출 모형을 2개 시험유역에 적용하여 실측 월유출량과 비교해 본 결과 본 모형은 춘추에는 약간 작게 추정하였고 그 외의 기간에는 약간 크게 추정하는 성향을 보였으나 대체로 만족스러운 결과를 주었으므로 미계측 하천의 월유출량 추정모형으로 사용 가능한 것으로 판단하였다.

• 대한수학회지
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• 제59권5호
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• pp.891-909
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• 2022

The main objective of this paper is to develop a concrete inverse formula of the system induced by the fourth-order finite difference method for two-point boundary value problems with Robin boundary conditions. This inverse formula facilitates to make a fast algorithm for solving the problems. Our numerical results show the efficiency and accuracy of the proposed method, which is implemented by the Thomas algorithm.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1384-1388
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• 2003

In structural fires, flashover is characterized by the rapid transition in fire behavior from localized burning of fuel to the involvement of all combustibles in the enclosure. An investigation of parameter effects on the time to reach flashover conditions in a typical single room fire is undertaken using a zone method (FAST) and Thomas method. Major parameters affecting the time to reach flashover are found to be fire growth rate, ventilation opening area and internal room surface. The results of the FAST and the Thomas Method give very similar results of the time to reach flashover..

• Communications for Statistical Applications and Methods
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• 제20권6호
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• pp.455-466
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• 2013

In nested case-control studies, the most common way to make inference under a proportional hazards model is the conditional logistic approach of Thomas (1977). Inclusion probability methods are more efficient than the conditional logistic approach of Thomas; however, the epidemiology research community has not accepted the methods as a replacement of the Thomas' method. This paper promotes the inverse probability weighting method originally proposed by Samuelsen (1997) in combination with an approximate jackknife standard error that can be easily computed using existing software. Simulation studies demonstrate that this approach yields valid type 1 errors and greater powers than the conditional logistic approach in nested case-control designs across various sample sizes and magnitudes of the hazard ratios. A generalization of the method is also made to incorporate additional matching and the stratified Cox model. The proposed method is illustrated with data from a cohort of children with Wilm's tumor to study the association between histological signatures and relapses.

• Korean Journal of Mathematics
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• 제13권2호
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• pp.139-148
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• 2005

In this paper we extend the mixed finite element method and its $L_2$-error estimate for postprocessed solutions by using Crank-Nicolson time-discretization method. Global $O(h^2+({\Delta}t)^2)$-superconvergence for the lowest order Raviart-Thomas element ($Q_0-Q_{1,0}{\times}Q_{0,1}$) are obtained. Numerical examples are presented to confirm superconvergence phenomena.

• 충청수학회지
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• 제36권1호
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• pp.55-64
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• 2023

In this paper, we propose a two-level overlapping domain decomposition preconditioner for three dimensional vector field problems posed in H(div). We introduce a new coarse component, which reduces the computational complexity, associated with the coarse vertices. Numerical experiments are also presented.

• 한국전문물리치료학회지
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• 제26권1호
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• pp.75-83
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• 2019

Background: A tight iliotibial band (ITB) may lead to lateral patellar maltracking, compression, and tilt, and dominant vatus lateralis (VL) muscle activation relative to vastus medialis oblique (VMO) can laterally displace the patella, which leads to anterior knee pain. Therefore, an effective management technique is needed to stabilize the patella in individuals with tight ITB. Increased stability during the modified Thomas test has the potential to decrease compensatory motion and thus to selectively stretch the ITB. Objects: The purpose of this study was to determine the effects of ITB stretching in the modified Thomas test position on ITB flexibility, patellar translation, and muscle activities of the VMO and VL during quadreceps-setting (QS) exercise in individuals with tight ITB. Methods: Twenty-one subjects with tight ITB were recruited. Digital inclinometer was used to measure the hip adduction angle during the modified Ober test. Universal goniometer was used to measure the hip abduction angle during the modified Thomas test. Ultrasonography was used to measure the patella-condylar distance. Electromyography was performed to collect data of muscle activities. Paired t-test was used to determine the statistical significance between pretest and posttest. Results: The range of hip adduction in modified Ober test increased (p=.04) and the range of hip abduction in the modified Thomas test decreased after ITB stretching (p<.01). There was no difference between lateral patellar translation (p=.18). VMO muscle activity significantly increased after ITB stretching during QS (p<.01). VL muscle activity had no difference after stretching. Conclusion: The ITB stretching in the modified Thomas test position can be suggested as a management method for improving ITB flexibility and VMO muscle activity in individuals with tight ITB.

• Journal of Chest Surgery
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• 제33권8호
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• pp.613-622
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• 2000

Background: The aim of this study is to define the cardioprotective effects(functional and metabolic) of newly developed DelNido cardioplegic solution(containing plasma solution, mannitol, magnesium and lidocaine). Material and Method: This study assessed the function of rat hearts after itermittent infusion of DelNido cardioplegia with different preserving methods(Air or Icebox) for 2hours and perfusing the hearts on a Langendorff apparatus. Heart rate, left ventricular developed pressure(LVDP) and coronary flow, were measured at pre-ischemic, post-reperfusion 15min, 30min and 45min. Coronary flow was standardized to dry heart weight. Each weight was weighted to calculate water content. Creatine kinase-MB isoenzyme release was measured and ultrastructural assessment was done with electron microscopes. Result: DelNido group was better than St, Thomas group and Icebox group was better than Room-air group. Conclusion: DelNido cardioplegia have better myocardial protective effects than St. Thomas cardioplegia when they were preserved in the Room-air. But we can not tell the difference between Delnido cardiplegia with Air preserving method and St. Thomas cardioplegia with Icebox.

• Korean Journal of Mathematics
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• 제21권3호
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• pp.293-304
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• 2013

In this paper we analyze an error estimator for the lowest-order triangular Raviart-Thomas mixed finite element which is based on solution of local problems for the error. This estimator was proposed in [Alonso, Error estimators for a mixed method, Numer. Math. 74 (1996), 385{395] and has a similar concept to that of Bank and Weiser. We show that it is asymptotically exact for the Poisson equation if the underlying triangulations are uniform and the exact solution is regular enough.

• 대한수학회보
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• 제38권2호
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• pp.237-260
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• 2001

The approximation properties for $L^2$-projection, Raviart-Thomas projection, and inverse inequality have been derived in 3 dimensional space. h-p-mixed finite element methods for strongly nonlinear second order elliptic problems are proposed and analyzed in 3D. Solvability and convergence of the linearized problem have been shown through duality argument and fixed point argument. The analysis is carried out in detail using Raviart-Thomas-Nedelec spaces as an example.