• Korean Journal of Optics and Photonics
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• v.5 no.3
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• pp.356-363
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• 1994

By Gaussian optics, a zoom eyepiece is analyzed, which has the diameter of exit pupil 0.5 em, eyerelief 1 em, and angular magnification $M_a=7~15$. The initial design is based on this analysis. Telescope objective which was previously designed has focal length($(f_u')$ 21.0 em, and its clear aperture is 6.2 em. Zoom telescope has half field angle $\beta=1.5^{\circ}$ at the entrance pupil and at exit pupil it is $\beta'=1.5^{\circ}\times(7~15)=10.5^{\circ}~22.5^{\circ}$. Zoom eyepiece consists of three groups, of which each one satisfies the Seidel 3,d order aplanatization. Final design is obtained by optimization for the finite ray aberration, and the zoom eyepiece is assessed on the basis of the resolution of eyes.f eyes.

• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3046-3054
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• 2013

Synthesis of Carbon Nanotube bundles has been achieved by simple and economical solvothermal procedure at very low temperature of $180^{\circ}C$. The product yield obtained was about 70-75%. The optimization of reaction conditions for an efficient synthesis of CNTs has been presented. The CNTs are obtained by reduction of hexachlorobenzene in the presence of Na/Ni in cyclohexane. The X-ray diffraction, Fourier transform infrared and Raman spectral studies have inferred us the graphene structure of the products. The CNTs formed as the bundles were viewed on scanning electron microscope, transmission electron microscope and high-resolution transmission electron microscope. These are the multiwalled CNTs with outer diameter of 5-10 nm, the inner diameter 2-4 nm and cross sectional diameter up to 5 nm. Brunauer-Emmett-Teller (BET) based $N_2$ gas adsorption studies have been made to obtain BET surface area and $H_2$ storage capacity. Effect of the experimental variables such as reaction temperature, amount of catalyst and the amount of carbon source were investigated. It is found that they affect significantly on the product nature and yield.

• Progress in Superconductivity and Cryogenics
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• v.23 no.3
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• pp.41-44
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• 2021

We developed an optimization process of the pulsed laser deposition method to grow epitaxial CeCoIn₅ thin films on MgF₂ substrates. The effects of different deposition parameters on film growth were extensively studied by analyzing the measured X-ray diffraction patterns. All the deposited films contained small amounts of CeIn₃ impurity phase and misoriented CeCoIn₅, for which the c-axis of the unit cell is perpendicular to the normal vector of the substrate surface. The deposition temperature, target composition, laser energy density, and repetition rate were found effective in the formation of (00l)-oriented CeCoIn₅ as well as the undesired phases such as CeIn₃, misoriented CeCoIn₅ along the (112) and (h00). Our results provide a set of deposition parameters that produce high-quality epitaxial CeCoIn₅ thin films with sufficiently low amounts of impurity phases and can serve as a reference for future studies to optimize the deposition process further.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.3
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• pp.133-147
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• 2005

Various types of ray-tracing methods are used to predict the quantity measures of radiation illumination, the uniformity of illumination, radiation performance of LCD BLU(Hack-Light Unit). The uniformity of radiation illumination is one of the most important design factor of BLU and is usually controlled by the diffusive-ink pattern printed on the bottom of light-guide panel of BLU. Therefore it is desirable to produce an improved (ideally, the optimal) ink pattern to achieve the best uniformity of radiation illumination. In this paper, we applied the Welder-Mead simplex-search method among various direct search method to compute the optimal ink pattern. Direct search methods are widely used to optimize the functions which are often highly nonlinear, unpredictably discontinuous, and nondifferentiable, The ink-pattern controlling the uniformity of radiation illumination is one type of these functions. In this paper, we found that simplex search methods are well suited to computing the optimal diffusive-ink pattern. In extensive numerical testing, we have found the simplex search method to be reasonably efficient and reliable at computing the optimal diffusive-ink pattern. The result also suggests that optimization can improve the functionality of simulation tools which are used to design LCD BLU.

• Journal of Radiation Industry
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• v.17 no.4
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• pp.471-479
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• 2023

In In-situ radioactivity measurement techniques, efficiency calibration models use predefined models to simulate a sample's geometry and radioactivity distribution. However, simplified efficiency calibration models lead to uncertainties in the efficiency curves, which in turn affect the radioactivity concentration results. This study aims to develop an efficiency calibration optimization methodology to improve the accuracy of in-situ gamma radiation measurements for byproducts from industrial facilities. To accomplish the objective, a drive mechanism for rotational measurement of an byproduct simulator and a sample was constructed. Using ISOCS, an efficiency calibration model of the designed object was generated. Then, the sensitivity analysis of the efficiency calibration model was performed, and the efficiency curve of the efficiency calibration model was optimized using the sensitivity analysis results. Finally, the radiation concentration of the simulated subject was estimated, compared, and evaluated with the designed certification value. For the sensitivity assessment of the influencing factors of the efficiency calibration model, the ISOCS Uncertainty Estimator was used for the horizontal and vertical size and density of the measured object. The standard deviation of the measurement efficiency as a function of the longitudinal size and density of the efficiency calibration model decreased with increasing energy region. When using the optimized efficiency calibration model, the measurement efficiency using IUE was improved compared to the measurement efficiency using ISOCS at the energy of ²²⁸Ac (911 keV) for the nuclide under analysis. Using the ISOCS efficiency calibration method, the difference between the measured radiation concentration and the design value for each simulated subject measurement direction was 4.1% (1% to 10%) on average. The difference between the estimated radioactivity concentration and the design value was 3.6% (1~8%) on average when using the ISOCS IUE efficiency calibration method, which was closer to the design value than the efficiency calibration method using ISOCS. In other words, the estimated radioactivity concentration using the optimized efficiency curve was similar to the designed radioactivity concentration. The results of this study can be utilized as the main basis for the development of regulatory technologies for the treatment and disposal of waste generated during the operation, maintenance, and facility replacement of domestic byproduct generation facilities.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.469-474
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• 2005

Tn this study, the noll-destructive computed X-ray tomography was adopted to observe the density distribution of the needle-punched C-C composites nozzle throat. The density distribution of the C-C was evaluated within ${\pm}0.01g/cm^3$ with 98.74% confidence when the correction of the image and high signal-to-noise ratio were achieved by the optimization of the beam hardening, the electrical noise and the scattered X-ray. The density variation of the C/C with the computed tomography was in good agreement with the results obtained by the water immersion method and the observation with scanning electron microscope.

• Environmental Engineering Research
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• v.14 no.2
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• pp.81-87
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• 2009

The decomposition of antibiotics (cefaclor) by gamma irradiation in aqueous solutions was experimentally evaluated. To obtain a mutual interaction between two factors (antibiotics concentrations and radiation doses) and to optimize these factors during the process, experimental design and statistical analysis were employed. The decomposition capability of the gamma radiation was also mathematically described as a function of cefaclor concentration and gamma-ray dose using the statistical analysis. The results showed that the cefaclor concentration ($X_1$) in the response $Y_1$ (Reduction of cefaclor concentration) and gamma-ray dose ($X_2$) in the response $Y_2$ (Removal efficiency (%) of cefaclor concentration) exhibited a significantly positive effect, whereas gamma-ray dose ($X_2$) in the response $Y_1$ showed a significantly negative effect. The estimated ridge of maximum responses and optimal conditions for $Y_1$:($X_1$,$X_2$)=(25 mg/L, 350 Gy) and $Y_2$:($X_1$,$X_2$)=(21 mg/L, 565 Gy) using canonical analysis were 4.37 mg/L of reduction of cefaclor concentration and 98.35% of removal efficiency of cefaclor concentration, respectively. The measurement values agreed well with the predicted ones, thereby confirming the suitability of the model for $Y_1$ and $Y_2$ and the success of the experimental design in optimizing the conditions of the gamma irradiation process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.3
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• pp.213-218
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• 2017

In this study, a reverse design of the F-theta lens was proposed for a 2D scanner in remote welding applications. The curvature and distance of the lens were set as variables, and the focal length of the lens was set as the marginal ray height. The ZEMAX commercial software was used to perform a simulation with unlimited iterations for the optimization process. The target value was optimized using the internal Merit function with the weight factors of focal length and spot diameter. The number of lenses was four, and the focal length obtained from the results was 135mm that is slightly less than that of the commercial lens, which is set with a focal length of 185 mm. The calculated spot diameters are $1.3{\mu}m$, $6.2{\mu}m$, and $16.1{\mu}m$ for $0^{\circ}$, $12.5^{\circ}$ and $23^{\circ}$ of incident laser beam, respectively. It is expected that an optimized lens design is possible by performing the reverse design of a lens by the ray tracing method.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.15-22
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• 2012

The purpose of this study was to measure the absorbed dose and calculate the effective dose for cone beam computed tomography (CBCT) and panorama units and to estimate usefulness of x-ray protective. Rando phantom and glass dosimeters were used for dosimetry. The absorbed doses were measured at 15 organs and 14 remainder from correspond to ICRP 2007 recommendations. The absorbed dose was highest in salivary glands as measured CBCT 2.420mGy, panorama 0.307mGy. Absorbed dose in another organs were high in order of thyroid, brain, skin, esophagus. The effective dose was CBCT 0.100mSv, panorama 0.011mSv and effective dose of panorama was higher than that of CBCT by 10 times. In case of wearing x-ray protective, reducing effective dose of CBCT by 0.066mSv (66%) and panorama by 0.008mSv (72%). Effective dose were reduced by radiological shielding but it needs further optimization studies, where dosimetric data are analyzed in combination with image quality with keep the patients' exposure as low as possible.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.463-469
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• 2016

In this study, a virtual specimen with a linear continuous gradient of void ratio (FGM: Functional Graded Material) is constructed using low-order probability functions of two real cement paste specimens. Two real specimens with difference void ratios are taken from X-ray CT to construct the virtual specimen. A virtual specimen with a gradient void distribution, whose average void ratio is between void ratios of two homogeneous real specimens, is constructed using a stochastic optimization approach. The void ratio distribution is assumed to be linear, and continuously varies in the vertical direction. In this study, a gradient term of void ratio is incorporated into the objective function as well as low-order probability functions from the previous research. To confirm the effect of gradient void distribution on the material response, air permeability is evaluated using finite element analysis. The analysis results are compared with experimental results, and confirm the effect of gradient void distribution on permeability.