• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.45-56
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• 1990

This study deals with the nonlinear strength analysis of laminated composite cylindrical shells to find the optimum structure of pressure vessel. By applying the F.E.M. using the 8-node degenerated Isoparametric shell element and Total Lagrangian formulation and being adopted Newton-Raphson method with incremental load as a solution scheme. the optimum structure is found from the viewpoint of minimum displacement. As a results of linear analysis on the 9 cases of laminated structure, $[50^{\circ}/-50^{\circ}]$ composition of the shell laminate give the minimum deflection. In case of the nonlinear analysis by applying Quadratic Failure Criteria on laminated combination $[{\theta}^{\circ}/-{\theta}^{\circ}]$, shell laminate structure of ${\theta}=50^{\circ}$ under external uniform pressure was founded as a optimum structure and ${\theta}=50^{\circ}$ for the case of external and axial loading combined.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.117-126
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• 1994

This paper describes an application step of a $R^{-{\theta}}$ method which measures circular movements in machining centers. The detection of composite errors of circular movements and a high precision cutting method in machining centers were investigated by the analysis of data measured by $R^{\theta }$method which can detect the rotating angle and is applicable to variable measuring radius. When the error by squareness error and unbalance of position-loop-gain were mixed, the detection method of each error was proposed. Although the errors by squarenss error and backlash compensation were mixed, the errors by squareness error be detected. If the errors by unbalance of position-loop-gain and backlash compensation were mixed, the errors by unbalance of position-loop-gain could not detected. A high precision cutting mehod, which uses the NC program compensated by using feed-back data from error measured by the $R^{\theta }$method, was proposed.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.74-79
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• 1994

The characteristics of the type I and type II SHG in LiB305 crystals grown by TSSG method have been investigated using 1064 nm beam from a Q-switched Nd:YAG laser. The measured phase matching angles and angular acceptance bandwidths were $\theta_m=90^{\circ}, \phi_m=11.6^{\circ}$, <$\delta\theta_{int}L_{1/2}=3.3^{\circ}-cm^{1/2}, \theta\phi_{int}L=0.27^{\circ}-cm^{1/2}$ for type I SHG and $\theta_m=20^{\circ}, \phi_m=90^{\circ}$, TEX>$\delta\theta_{int}L_=0.65^{\circ}-cm, \theta\phi_{int}L^{1/2}=3.5^{\circ}-cm^{1/2}$ for type II SHG, respectively. Thp. type I NCPM temperature of 1064 nm beam was found to be $149^{\circ}C$ with the temperature bandwidth $\DeltaTL$of $4.8^{\circ}C-cm$. An energy conversion efficiency of about 1.8% with 2.6 mm thick LBO crystal at an incident power of TEX>$171 MW/\textrm{cm}^2$ was demonstrated. The measured $d_{32} was 0.74\pm0.05 pm/V$..

• Computational Structural Engineering
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• v.10 no.2
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• pp.255-263
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• 1997

The optimum design of most structural systems used in practice requires considering design variables as discrete quantities. The present paper shows that the linear approximation method is very effective as a tool for the discrete optimum designs of unsymmetric composite laminates. The formulated design problem is subjected to a multiple in-plane loading condition due to shear and axial forces, bending and twisting moments, which is controlled by maximum strain criterion for each of the plys of a composite laminate. As an initial approach, the process of continuous variable optimization by FDM is required only once in operating discrete optimization. The nonlinear discrete optimization problem that has the discrete and continuous variables is transformed into the mixed integer programming problem by SLDP. In numerical examples, the discrete optimum solutions for the unsymmetric composite laminates consisted of six plys according to rotated stacking sequence were found, and then compared the results with the nonlinear branch and bound method to verify the efficiency of present method.

• Korean Journal of Hydrosciences
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• v.5
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• pp.85-97
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• 1994

A hybrid finite difference method for the longitudinal dispersion equation, which is based on combining the Holly-Preissmann scheme with fifth-degree Hermite interpolating polynomial and the generalized Crank-Nicholson scheme, is described and comparatively evaluated with other characteristics-based numerical methods. Longitudinal dispersion of an instantaneously-loaded pollutant source is simulated, and computational results are compared with the exact solution. The present method is free from wiggles regardless of the Courant number, and exactly reproduces the location of the peak concentration. Overall accuracy of the computation increases for smaller value of the weighting factor, $\theta$of the model. Larger values of $\theta$ overestimates the peak concentration. Smaller Courant number yields better accuracy, in general, but the sensitivity is very low, especially when the value of $\theta$ is small. From comparisons with the hybrid method using cubic interpolating polynomial and with splitoperator methods, the present method shows the best performance in reproducing the exact solution as the advection becomes more dominant.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.131-138
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• 1989

In this paper the feature of background EEG is extracted by LS Prony Method for the analysis of background EEG in the time domain. Autocorrelation leg estimates are not required with the LS Prony method. The Prony method is required any the solution of two serfs of simultaneous linear equation and a polynominal rooting. That the optimal order of this model is the 6-th order is determined by using Akaike' s Information Criterial test. From the experimential results the alpha band amplitude is the largest among alpha band beta band theta band delta band and beta band amplitude is larger than that of the delta band and theta band. The sustained time for the alph a band, the beta band, the delta band and the theta band is 2, 3461 (sec), 0.6490(sec), 0.3120(sec), 0.7046(sec) respectively. Consequenty the alpha band is maintained in the whole subjects, the beta band, the delta band, the theta band are existed intermittently in each subjects.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.16-17
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• 2006

In order to obtain spherical fine powder, we have developed a new method of high-pressure water atomization system using swirl water jet with the swirl angle $(\omega)$. The effect of nozzle apex angle $(\theta)$ upon the morphology of atomized powders was investigated. Molten copper was atomized by this method, with $\omega=0.2$ rad (swirl water jet) and $\omega=0$ rad (conical water jet). It was found that the median diameter $(D_{50})$ of atomized powders decreased with decreasing $(\theta)$ down to 0.35 rad in each $\omega$, but under ${\theta}<\;0.35$ rad, $D_{50}$ increased abruptly with decreasing $\theta$ for $\omega=0$ rad, while it was still decreased with decreasing $(\theta)$ for $\omega=0.2$ rad.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.1-6
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• 2021

In this study, we investigate the injection molding of f-theta lens, an important element of the laser scanning unit of laser printers and scanning systems. The f-theta lens is an aspherical plastic lens that must be molded with a precision of seconds. An injection molding method is often used for mass producing aspherical plastic lenses at a low cost. In the injection molding process, costs related to forming and injection are included. Therefore, in this study, to determine the shrinkage and deformation of injection molded f-theta lens, we predict the pressure and temperature distributions. Further, based on the analysis of the predictions, we maximize the design efficiency and verify the cost and development period reduction.

• Journal of the Korean Electrochemical Society
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• v.7 no.4
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• pp.194-200
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• 2004

The constant correlation factors between the Temkin and the Langmuir or the Frumkin adsorption isotherms of over-potentially deposited hydrogen (OPD H) for the cathodic H2 evolution reaction (HER) at poly-Pt and Re/0.5M $H_2SO_4$ and poly-Ni/0.05 M KOH aqueous electrolyte interfaces have been experimentally and consistently found using the phase-shift method. At intermediate values of the fractional surface coverage $(\theta),\;i.e.,\;02<{\theta}<0.8$, the Langmuir and Temkin adsorption isotherms of OPD H for the cathodic HER are correlated to each other even though the adsorption conditions or processes are different from each other. At the same range of $\theta$, correspondingly, the Frumkin and Temkin adsorption isotherms of OPD H for the cathodic HER are correlated to each other. The equilibrium constants $(K_o)$ for the Temkin adsorption isotherms $({\theta}\;vs.\; E)$ are consistently ca. 10 times greater than those (K, Ko) for the corresponding Langmuir or Frumkin adsorption isotherms ($({\theta}\;vs.\; E)$. The interaction parameters (g) for the Temkin adsorption isotherms $({\theta}\;vs.\; E)$ are consistently ra. 4.6 greater than those (g) for the corresponding Langmuir or Frumkin adsorption isotherms $({\theta}\;vs.\; E)$. These numbers (10 times and 4.6) can be taken as constant correlation factors between the corresponding adsolftion isotherms (Temkin, Langmuir, Frumkin) at the interfaces. The Temkin adsorption isotherm corresponding to the Langmuir or the Frumkin adsorption isotherm, and vice versa, can be effectively verified or confirmed using the constant correlation factors. Both the phase-shift methodand constant correlation factors are useful and effective for determining or confirming the suitable adsorption isotherms (Temkin, Langmuir, Frumkin) of intermediates for sequential reactions in electrochemical systems.

• Journal of Korean Academy of Nursing
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• v.31 no.5
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• pp.808-817
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• 2001

To survey the present status of the gerontological nursing course at three year diploma programs, baccalaureate degree programs(BSN), and graduate programs in Korea, and to analyze the contents of the syllabus and gerontological nursing textbooks to provide the basic data in developing a standard model for gerontological nursing curriculum. Method: Data was collected from all the nursing programs in Korea from Nov. 2000 to Feb. 2001 by mail and fax. Result: The gerontological nursing courses has been offered 36 diploma program, 40 BSN, and 17 graduate programs. And the credits of the gerontological nursing course offered by the program were as follows : one credit (10 diploma and 8 BSN), two credits (22 diploma and 29 BSN), and three credits (1 BSN). The contents of curri- culum were analyzed by comparing the core curriculum of NGNA. The majority of the schools included Gerontological Nursing in General, Theory of Aging, Aging Processes, Care Plan Options, and Common Health Problems. The subjects which very few school cover are Legal/ Ethical Issues, Evaluation, Regulatory & Reimbursement Issues, Education Issues, Nursing Research in Gerontology, and Environmental Issues of Older Adults. There were some differences in these results among diploma courses, BSNs, and graduate schools. The gerontological nursing textbooks contained similar contents to those of the diploma and the baccalaureate programs.