• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.611-615
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• 1991

A technique for estimation of the hydrodynamic parameter of an underwater vehicle is presented. An extended, augmented Kalman Filter is used to extract the hydrodynamic parameter. Computer generated data were used for the measurement information in lieu of actual run data. The feasibility of identifying values of the hydrodynamic parameter of an underwater vehicle is studied. Computer simulation are done in order to validate the performance of the proposed algorithm.

• 한국항해항만학회지
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• 제29권8호
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• pp.667-671
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• 2005

이 연구는 선박 설계 초기단계에서 선형 변화에 따른 선박 조종성능 추정에 관한 내용을 다루었다. 선박제원을 대표하는 파라메터 그리고 선미형상의 변화를 민감하게 반영할 수 있는 새로운 파라메터를 선정하는 작업을 수행하였다. 이렇게 선정된 파라메터와 유체력 미계수와의 상관관계를 알아보기 위하여 구속모형 실험을 수행하였다. 그 결과 기본적인 선박제원 중 선체 유체력 미계수와 상관도가 높은 파라메터를 가려낼 수 있었다. 또한 선미형상의 새로운 파라메터와 조종성능과의 상관도를 추정할 수 있었다. 또한 이를 활용하여 유체력미계수에 대한 새로운 경험식을 제시하였다. 이를 활용하면, 초기 선형 설계 시 선형변화 및 수정에 따른 조종성능 추정에 활용할 수 있을 것으로 판단된다.

• Bulletin of the Korean Chemical Society
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• 제22권11호
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• pp.1255-1260
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• 2001

The expansion of two different kinds of hydrodynamic size of polymethyl methacrylate (PMMA Mw: 1.56- 2.04 ${\times}$ 106 g/mol) has been measured by dynamic light scattering and viscometry above the Flory $\theta$ temperature of the variou s solvents such as n-butyl chloride, 3-heptanone, and 4-heptanone. The expansion of PMMA chains was analyzed in terms of universal temperature parameters and also compared with previous results of polystyrene (PS) system. First it was found that simple $\tau/{\tau}c$ parameter no longer had its universality for the expansion behavior of hydrodynamic size in the chemically different linear polymer chains. However after modifying ${\tau}/{\tau}c$ parameter into $(Mw/Ro2)3}2(\tau/\tauc)$, we observed a much better universality for both PMMA and PS systems. Here Mw, Ro, $\tau[=(T-{\theta}$)/${\theta}$]$, and ${\tau}c[=({\theta}-Tc)/Tc]$ are defined as the weight average molecular weight, the unperturbed end-to-end distance, the reduced temperature and the reduced critical temperature, respectively.

• 대한전자공학회논문지
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• 제27권3호
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• pp.63-71
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• 1990

Hydrodynamic model에 의해서 submicron GaAs device를 simulation 할 때 필요한 hydrodynamic model parameter 들을 Monte Carlo code를 개발하여 추출하였다. GaAs 전도대의 밴드구조로 $\Gamma$, L, X세개의 valley를 고려하였고, 산란기구로는 polar optic phonon, acoustic phonon, equivalent intervalley, non-equivalent intervalley, ionized impurity 및 piezoelectric scattering을 고려하였다. 계산으로부터 얻은 속도 - 전계 곡선은 실험결과와 잘 일치하였고, 다른 연구자들이 소자 시뮬레이션에 사용할 수 있도록 모델 파라메터들을 표로 제시하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.103-107
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• 2005

연구는 선박 설계 초기단계에서 선형 변화에 따른 선박 조종성능 추정에 관한 내용을 다루었다. 선박제원을 대표하는 파라메터 그리고 선미형상의 변화를 민감하게 반영할 수 있는 새로운 파라메터를 선정하는 작업을 수행하였다. 이렇게 선정된 파라메터와 유체력 미계수와 상관관계를 알아보기 위하여 구속모형 실험을 수행하였다. 그 결과 기존의 기본적인 선박제원 중 상관도가 높은 파라메터를 가려낼 수 있었다. 또한 선미형상의 새로운 파라메터와 조종성능과의 상관도를 추정할 수 있었다. 이를 활용하면,초기 선형 설계시 선형변화 및 수정에 따른 조종성능 추정에 활용할 수 있을 것으로 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권1호
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• pp.37-52
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• 2020

Sensitivity analysis of hydrodynamic and reaction parameters in conceptual model reflecting aquifer characteristics of Korea was performed to evaluate the uncertainty in the predicted concentrations. Among the hydrodynamic input parameters, both hydraulic conductivity (K_x) and hydraulic gradient (I) affected transport behaviors of contaminants, and resulted in same convergence concentrations with continuous injections of contaminant. However, longitudinal dispervisity (α_L) affected both transport behaviors and the convergence concentrations of contaminants. Compared to the hydrodynamic parameters, growth kinetic and degradation parameters (μ_m & K_c) more significantly affected both transport behaviors and the convergence concentrations of contaminants, indicating those parameters had higher sensitivity indices causing the uncertainties of model predictions. Considering that the sensitivity indices of both hydrodynamic and reaction parameters were a function of transport distance of groundwater, the parameters with higher sensitivity indices, a priori, need to be investigated using conceptual model reflecting site-specific aquifer characteristics before field investigation. After determining the parameters with higher sensitivity indices, the detail field investigations for the selected hydrodynamic and reaction parameters were warranted to reduce the uncertainties of model predictions.

• 한국해양공학회지
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• 제37권5호
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• pp.198-204
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• 2023

In response to the complexity and time demands of conventional methods for estimating the hydrodynamic coefficients, this study aims to revolutionize ship maneuvering analysis by utilizing automatic identification system (AIS) data and the Support Vector Regression (SVR) algorithm. The AIS data were collected and processed to remove outliers and impute missing values. The rate of turn (ROT), speed over ground (SOG), course over ground (COG) and heading (HDG) in AIS data were used to calculate the rudder angle and ship velocity components, which were then used as training data for a regression model. The accuracy and efficiency of the algorithm were validated by comparing SVR-based estimated hydrodynamic coefficients and the original hydrodynamic coefficients of the Mariner class vessel. The validated SVR algorithm was then applied to estimate the hydrodynamic coefficients for real ships using AIS data. The turning circle test wassimulated from calculated hydrodynamic coefficients and compared with the AIS data. The research results demonstrate the effectiveness of the SVR model in accurately estimating the hydrodynamic coefficients from the AIS data. In conclusion, this study proposes the viability of employing SVR model and AIS data for accurately estimating the hydrodynamic coefficients. It offers a practical approach to ship maneuvering prediction and control in the maritime industry.

• 대한기계학회논문집
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• 제15권2호
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• pp.630-643
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• 1991

The hydrodynamic stability equations are formulated for buoyancy-induced flows adjacent to a vertical, planar, isothermal surface in cold pure water. The resulting stability equations, when reduced to ordinary differential equation by a similarity transformation, constitute a two-point boundary-value(eigenvalue) problem, which was numerically solved for various values of the density extremum parameter R=( $T_{m}$ - $T_.inf./) / ( $T_{o}$ - $T_.inf./). These stability equations have been solved using a computer code designed to accurately solve two-point boundary-value problems. The present numerical study includes neutral stability results for the region of the flows corresponding to 0.0.leq. R. leq.0.15, where the outside buoyancy force reversals arise. The results show that a small amount of outside buoyancy force reversal causes the critical Grashof number $G^*/ to increase significantly. A further increase of the outside buoyancy force reversal causes the critical Grashof number to decrease. But the dimensionless frequency parameter $B^*/ at $G^*/ is systematically decreased. When the stability results of the present work are compared to the experimental data, the numerical results agree in a qualitative way with the experimental data.erimental data.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.766-771
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• 1992

The hydrodynamic coefficients estimation problem is important to develop an underwater vehicle and design a controller for it. In this paper, an identification theory, the Extended Kalman Filter, is applied to this parameter estimation problem. In the case that a process noise is not used, all of the parameters are almost exactly converged to the true values respectively. When a process noise is used, all of the parameters are converged to the true values, too, although some parameter estimates are slightly biased. The comparisons of the two trajectories between those generated by the true parameters and those by the estimated parameters show that the parameter estimation problem is well-solved.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1667-1670
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• 1997

We consider the probelem of identifying and underwater vehicle. It is assumed that a priori information about the parameteric model structure and values of the hydrodynamic coefficients is available from some other schemes. The concept of relative esnsitivity is introduced to plan and efficinet identification procedure. An analysis of the sensitivity of the overall system to a particular hydrodynamic coefficinet provides a tool to evaluate the relative importance of the same coefficient in a particular maneuver. Then it can be made possible to reduce the filter size by selecting some dominatn hydrodynamic coefficients as parameters to be estimated for a given maneuver, and this fact may be used for establishing a gradual identification scheme. The main merit of a gradual identification is substantially reduced computer burden with increased nimerical stability. An illustrative simualtion result is given.