• 대한조선학회논문집
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• 제33권2호
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• pp.1-12
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• 1996

본 논문에서는 갑판침입수의 유동특성을 단순화된 2차원 모델을 이용하여 고찰하였다. 기본방정식으로 천수파 모델에 기초한 보존형의 비선형 쌍곡선방정식이 도출되었고, 이를 계산하기 위한 시간영역 수치해법으로 predictor-corrector법과 2종 상류차분법을 채용한 유한차분법을 개발 적용하였다. 보아를 수반하는 몇가지 단순한 경우들에 대한 계산결과를 해석해와 비교하였으며, 본 수치해법이 갑판침입수의 유동해석에 유용한 방법임을 보였다. 갑판침입수의 유동 시뮬레이션 에들에서, 갑판침입수는 확산파의 형태로 감판상에 유입되며 갑판상의 구조물에 부딪힌 후 보아형태로 발달해 감이 보여지고 있다. 또한, 침입수 유동에 영향을 줄 수 있는 중요요소로서 갑판의 기울기, 상방향 가속도등이 다루어 졌고, 이들이 갑판 침입수의 유동에 상당한 영향을 미침을 확인하였다.

• 콘크리트학회논문집
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• 제21권6호
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• pp.781-788
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• 2009

강-콘크리트 계면의 성질을 대표하는 부착강도, 부착 및 비부착 마찰계수, 부착 및 비부착 마찰계수의 연화영역에서 잔류량의 크기, 모드 I 파괴에너지, 부착 및 비부착 모드 II 파괴에너지, 파괴포락선의 형상계수를 포함한 총 9개 계면상수의 값을 계면거동실험결과와 파괴포락선의 기하학적 형상 및 구성모델을 이용하는 민감도 해석을 통해 결정하였다. 계면의 거동이 계면의 부착상태뿐만 아니라 계면법선방향 응력의 방향과 크기에 따라 매우 민감하게 작용하므로 계면상수 값의 결정에서는 이러한 구속압의 크기와 부착 및 비부착 계면조건을 고려하였다. 강재판 사이에 콘크리트가 타설된 강-콘크리트 계면실험체의 거동해석을 위한 계면유한요소해석을 결정된 계면상수를 적용하여 수행하였으며 실험결과와의 비교를 통해 상수값의 적정성을 검토하였다.

• 대한토목학회논문집
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• 제13권2호
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• pp.11-20
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• 1993

쌍곡 포물선 '안장' 쉘의 극한(極限) 거동(擧動)을 슈퍼 컴퓨터에 개발한 유한요소(有限要素) 컴퓨터 프로그램으로 연구(研究)하였다. 잘게 자른 3 모델을($16{\times}16$, $32{\times}32$과 $64{\times}64$) 이용하여 탄성(彈性)과 비탄성(非彈性) 해석으로 유한요소 망(mesh)의 수렴관계를 연구하였으며, 해석 결과 $32{\times}32$ 모델의 해(解)가 $64{\times}64$ 모델의 결과에 매우 가깝게 나타나서, 이 모델이 수렴하고 있음을 보여 주었다. 비탄성(非彈性) 해석 결과(結果) '안장' 쉘이 상당한 응력(應力)재분포 능력(能力)을 갖고 있었으며, 극한 상태에서 콘크리트의 균열과 철근의 항복이 전체 젤에 걸쳐서 나타났다. 이 현상에 따라 응력 분포가 고전적인 막이론(膜理論)(Membrane theory)의 결과에 접근하고 있음을 관찰할 수 있었다. 개발된 컴퓨터 프로그램은 설계시에 콘크리트 쉘구조물의 비선형 극한거동을 산정하는데 매우 유용하게 사용될 수 있을 것이다.

• Geomechanics and Engineering
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• 제23권4호
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• pp.313-325
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• 2020

Slope displacement and factor of safety (FOS) of a slope are two aspects that reflect the stability of a slope. However, the traditional limit equilibrium (LE) methods only give the result of the slope FOS and cannot be used to solve for the slope displacement. Therefore, developing a LE method to obtain the results of the slope FOS and slope displacement has significance for engineering applications. Based on a force-displacement coupled mode, this work expands the LE Morgenstern-Price (M-P) method. Except for the mechanical equilibrium conditions of a sliding body adopted in the traditional M-P method, the present method introduces a nonlinear model of the shear stress and shear displacement. Moreover, the energy equation satisfied by a sliding body under a small slope displacement is also applied. Therefore, the double solutions of the slope FOS and horizontal slope displacement are established. Furthermore, the flow chart for the expanded LE M-P method is given. By comparisons and analyses of slope examples, the present method has close results with previous research and numerical simulation methods, thus verifying the feasibility of the present method. Thereafter, from the parametric analysis, the following conclusions are obtained: (1) the shear displacement parameters of the soil affect the horizontal slope displacement but have little effect on the slope FOS; and (2) the curves of the horizontal slope displacement vs. the minimum slope FOS could be fitted by a hyperbolic model, which would be beneficial to obtain the horizontal slope displacement for the slope in the critical state.

• Communications for Statistical Applications and Methods
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• 제16권1호
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• pp.51-65
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• 2009

제 1상 임상시험은 사람을 대상으로 처음 실시되므로 약물 투여의 안전성과 정확성이 신중히 고려되어야 한다. 따라서 제 1상 임상시험에서는 적은 수의 피험자를 통해 최대허용용량(maximum tolerated dose)을 정확하게 찾아야 한다. 제 1상 임상시험에서 최대허용용량을 결정하는 방법에는 표준방법(standard method), 연속재평가방법(continual reassessment method) 그리고 가속적정계획(accelerated titration designs) 방법이 있다. 본 연구에서는 동일한 모형에서 세 방법을 동시에 고려하여 최대허용용량의 안전성과 정확성을 살펴보았다. 또한 세 방법에 대해 최대허용용량에서 기대독성확률을 구하여 비교하였다. 그리고 ATD와 CRM의 단점을 보완한 수정된 ATD와 수정된 CRM을 포함하여 여러 방법들을 동일한 모형에서 동시에 그 성능을 비교하였다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 제11차 KACG 학술발표회 Crystalline Particle Symposium (CPS)
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• pp.285-309
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• 1996

Non oxide ceramics such as nitrides of transition metals have shown significant potential for future economic impact, in diverse applications in ceramic, aerospace and electronic industries, as refractory products, abrasives and cutting tools, aircraft components, and semi-conductor substrates amid others. Combustion synthesis has become an attractive alternative to the conventional furnace technology to produce these materials cheaply, faster and at a higher level of purity. However he process os highly exothermic and manifests complex dynamics due to its strongly non-linear nature. In order to develop an understanding of this process and to study the effect of operational parameters on the final outcome, numerical modeling is necessary, which would generated essential knowledge to help scale-up the process. the model is based on a system of parabolic-hyperbolic partial differential equations representing the heat, mass and momentum conservation relations. The model also takes into account structural change due to sintering and volumetric expansion, and their effect on the transport properties of the system. The solutions of these equations exhibit steep moving spatial gradients in the form of reaction fronts, propagating in space with variable velocity, which gives rise to varying time scales. To cope with the possibility of extremely abrupt changes in the values of the solution over very short distances, adaptive mesh techniques can be applied to resolve the high activity regions by ordering grid points in appropriate places. To avoid a control volume formulation of the solution of partial differential equations, a simple orthogonal, adaptive-mesh technique is employed. This involves separate adaptation in the x and y directions. Through simple analysis and numerical examples, the adaptive mesh is shown to give significant increase in accuracy in the computations.

• Wind and Structures
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• 제19권4호
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• pp.443-465
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• 2014

Hyperbolic thin-shell cooling towers have complicated vibration modes, and are very sensitive to the effects of group towers and wind-induced vibrations. Traditional aero-elastic models of cooling towers are usually designed based on the method of stiffness simulation by continuous medium thin shell materials. However, the method has some shortages in actual engineering applications, so the so-called "equivalent beam-net design method" of aero-elastic models of cooling towers is proposed in the paper and an aero-elastic model with a proportion of 1: 200 based on the method above with integrated pressure measurements and vibration measurements has been designed and carried out in TJ-3 wind tunnel of Tongji university. According to the wind tunnel test, this paper discusses the impacts of self-excited force effect on the surface wind pressure of a large-scale cooling tower and the results show that the impact of self-excited force on the distribution characteristics of average surface wind pressure is very small, but the impact on the form of distribution and numerical value of fluctuating wind pressure is relatively large. Combing with the Complete Quadratic Combination method (hereafter referred to as CQC method), the paper further studies the numerical sizes and distribution characteristics of background components, resonant components, cross-term components and total fluctuating wind-induced vibration responses of some typical nodes which indicate that the resonance response is dominant in the fluctuating wind-induced vibration response and cross-term components are not negligible for wind-induced vibration responses of super-large cooling towers.

• 수산경영론집
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• 제50권2호
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• pp.41-56
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• 2019

The aim of this study is to analyze the productivity change of pollock enterprise by applying a mutually quadratic hyperbolic model and a bootstrapping model. This study used 20 units of pollock firms data (from 2013 to 2017). As a result of total productivity analysis of twenty pollock enterprises, total factor productivity was estimated to have decreased by 24.9% over the last five years (2013~2017). The main cause of this productivity decline was analyzed by technical change. In terms of annual productivity change, it showed decrease 3.0% in 2013~2014, 7.8% in 2014~2015, 4.5% in 2015~2016 and 4.7% in 2016~2017 respectively. In the analysis of productivity by corporation type, total factor productivity showed a significant decrease in both general corporation and external corporation, and productivity decrease (-29.3%) was larger than general corporation (-23.0%). In the productivity analysis by type of business, total factor productivity decreased significantly in the order of wholesale and commodity brokerage (-26.3%), food manufacturing (-25.1%) and fisheries (-15.3%). This decrease in productivity was caused by the technological change which indicates a downward shift in the production curve that is significant in all sectors.

• Smart Structures and Systems
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• 제32권5호
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• pp.319-338
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• 2023

The study presents a new hybrid data-driven method by combining radial basis functions neural networks (RBF-NN) with the Jaya algorithm (JA) to provide effective structural health monitoring of arch dams. The novelty of this approach lies in that only one user-defined parameter is required and thus can increase its effectiveness and efficiency, as compared to other machine learning techniques that often require processing a large amount of training and testing model parameters and hyper-parameters, with high time-consuming. This approach seeks rapid damage detection in arch dams under dynamic conditions, to prevent potential disasters, by utilizing the RBF-NNN to seamlessly integrate the dynamic elastic modulus (DEM) and modal parameters (such as natural frequency and mode shape) as damage indicators. To determine the dynamic characteristics of the arch dam, the JA sequentially optimizes an objective function rooted in vibration-based data sets. Two case studies of hyperbolic concrete arch dams were carefully designed using finite element simulation to demonstrate the effectiveness of the RBF-NN model, in conjunction with the Jaya algorithm. The testing results demonstrated that the proposed methods could exhibit significant computational time-savings, while effectively detecting damage in arch dam structures with complex nonlinearities. Furthermore, despite training data contaminated with a high level of noise, the RBF-NN and JA fusion remained the robustness, with high accuracy.

• 대한약리학회지
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• 제31권2호
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• pp.251-259
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• 1995

Pharmacokinetics and pharmacodynamics of metoprolol, a selective beta-l blocker, were examined for 360 minutes after intravenous bolus administration of metoprolol to 6 dogs. Plasma concentration and excreted amount in the urine metoprolol were measured by liquid chromatography with fluorescence detection. PR interval and heart rate were measured by ECG monitoring. Blood pressure was monitored through intraarterial catheter in femoral artery and cardiac output by thermodilution method using Swan-Ganz catheter. To analyze the effect site concentration-response relationship, plasma concentration and pharmacological effects were simultaneously fitted to a two pharmacokinetic compartment linked to pharmacodynamic model with NONLIN program. Results are as follows. 1) The plasma concentration of metoprolol after intrvenous injection decreased biexponentially. The terminal half-life estimated was $1.33{\pm}0.40$ hours and the volume of distribution at steady state (Vdss) and the total body clearance were $1.04{\pm}0.4\;L/kg,\;6.55{\pm}2.21\;L/hr$, respectively. The central compartment volume of distribution and peripheral compartment volume of distribution were $0.35{\pm}0.14L/kg\;and\;0.69{\pm}0.34L/kg$. The renal clearance and intercompartment clearance were $0.53{\pm}0.25\;L/min\;and\;0.35{\pm}0.19\;L/min$. 2) Simulated biophase concentration-response curve shows hyperbolic relationship and the estimated concentration-effect relationship was best explained by Emax model when the prolongation of PR interval and the reduction of the heart rate were used as pharmacodynamic parameters. Emax and EC50 were estimated to be $26.3{\pm}4.7\;msec\;and\;88.8{\pm}82.3\;g/ml$ for PR interval, and $48.7{\pm}18.8\;beats/min\;and\;113.5{\pm}78.7\;ng/ml$ for heart rate, respectively. 3) The changes of cardiac output-effect site concentration relationship was best fitted by a linear model and the slope of the relationship was $0.005{\pm}0.003$. Diastolic blood pressure-effect site concentration relationship was also explained by the linear model and the slope of the relationship was $0.038{\pm}0.034$.