• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.311-316
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• 2020

The main cause of DMSMS is the rapid replacement cycle and short life cycle of parts, according to the development of science, compared to the long life cycle of weapons systems. In particular, the problem of the supply and demand of such parts becomes even more acute during the operation maintenance phase after the mass production and power generation stage. To eliminate DMSMS problems that arise continuously from development to the operation of weapon systems and select the most cost-effective countermeasures to obsolescence, this paper suggests a standard to determine the appropriate time for quantitative performance improvement by conducting total life cycle cost analysis. For such purpose, this study examined the domestic and overseas cost analysis methods and applied it to single domestic weapon system to verify the research. This study responds to the issue of discontinuing components and helps reduce the total life cycle cost of military products.

• Journal of the Korean Vacuum Society
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• v.16 no.5
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• pp.371-376
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• 2007

We have investigated the lasing characteristics of the InGaAs quantum dot laser diode (QD-LD) and InGaAs quantum well laser diode (QW-LD) operated at the 980 nm wavelength range. The 980-nm lasers are used as a pumping source for a erbium-doped fiber amplifier (EDFA) and it shows high efficiency in long-haul optical fiber network. We have compared the threshold current density, the characteristic temperature, the optical power and the internal efficiency of QD-LD and QW-LD under a pulsed current condition. The QD-LD shows superior performances to the QW-LD. Further optimization of a LD structure is expected to the superior performances of a QD-LD.

• Korean journal of food and cookery science
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• v.28 no.6
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• pp.805-811
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• 2012

This study was carried out in order to optimize the manufacturing condition of fried garlic flakes as well as to investigate the physicochemical properties of the flakes. Fried garlic flake samples were prepared as follows: garlic was sliced by a thickness of 1.5 mm, 2.0 mm, 2.5 mm, which were measured by a thickness gage. The samples were fried in vegetable oil under different temperatures of $140{\sim}150^{\circ}C$, $160{\sim}170^{\circ}C$ and $180{\sim}185^{\circ}C$. The compression strength depending on the height (h) was measured in order to find the thickness effect by the rheometer (force control: 50 N, h: 3.25 mm). Moreover, the sample with 1.5 mm thickness showed crisp phenomena of the split compared with the crush shape of the 2.0 mm and 2.5 mm thick samples. The result of strength for time dependence showed a sample with a thickness of 1.5 mm, which was measured 5~9 times more than the 2.0 mm and 2.5 mm thick samples. We thought the reason that the 1.5 mm sample had less response power equivalent to compression force than the other samples. Alliin has been found to affect the immune responses in the blood, it is a derivative of the amino acid cysteine and is also quite heat stable. The LC system with a UV detection at 210 nm consists of a separation on a Zorbax TMS column and isocratic elution with water and ACN as a mobile phase. The alliin contents of raw and fried garlic flake under $140{\sim}150^{\circ}C$, $160{\sim}170^{\circ}C$ and $180{\sim}185^{\circ}C$ were 18.10 mg/mL, 14.0 mg/mL, 11.6 mg/mL and 11.1 mg/mL, respectively. The decrement of alliin content under different temperature was a small quantity hence, we confirmed that the increasing manufacturing temperature was not affected by the alliin content. Examining for the particle structure of fried garlic flakes by a polarization microscope, the color of the sample treated at $160{\sim}170^{\circ}C$ was pure yellow. Furder, the fiber shaped particle, which has an effect on the tough texture, almost did not appear compared to the different temperature conditions. Finally, the sensory test for the preference of fried garlic flake under different conditions was carried out and the scores for various sensory characteristics were surveyed. According to the physicochemical measurements and sensory evaluation, we confirmed that the optimum manufacturing condition of fried garlic flake was 1.5 mm thick at a temperature of $160{\sim}170^{\circ}C$.

• Journal of Digital Convergence
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• v.14 no.4
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• pp.419-424
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• 2016

In this paper, we studied a light distribution for the LED chips arrangement using an optical design software. The structures of the edge type LED luminaires are reflector plane, LGP(lighting guide plane) and diffuse plane. The reflector plane is on the middle of the overall structure. We had simulation that placing LED chips on the reflector center of the reflector edge by changing the position of LED chips above the reflector center at 1mm, 2mm, and 3mm respectively. In the case, when LED chips are on the center of the reflector, it shows the light distribution of the general diffuse illumination, the semi-direct distribution with 0.56 efficiency and the direct distribution with 0.31 efficiency. And the wedge type LGP shows more efficiency than the flat type. Gradually increasing shape of semi-spherical type by 0.015mm has power of 1.02W, efficiency of 0.25, and maximum luminous intensity of 0.104W/sr, it also and shows the better optical characteristics than the reflector plane that have no patterns. This semi-spherical type shows the better optical characteristics than the reflector plane that have no patterns.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.656-662
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• 2013

The iron oxide ($Fe_3O_4$) particles in the coolant of the secondary system of a nuclear power plant reduce the heat transfer performance or induce corrosion on the surface of the heat transfer tube. To prevent these problems, we conducted a study to improve the dispersion stability of iron oxide using polymeric dispersant injection in simulated secondary system water. The three kinds of anionic polymers containing carboxyl groups were selected. The dispersion characteristics of the iron oxide particles with the polymeric dispersants were evaluated by performing a settling test and measuring the transmission, the zeta potential, and the hydrodynamic particle size of the colloid solutions. Polymeric dispersants had a significant impact on the iron oxide dispersion stability in an aqueous solution. While the dispersant injection tended to improve the dispersion stability, the dispersion stability of iron oxide did not increase linearly with an increase in the dispersant concentration. This non-linearity is due to the agglomerations between the iron oxide particles above a critical dispersant concentration. The effect of the dispersant on the dispersion stability improvement was significant when the dispersant concentration ratio (ppm, dispersant/magnetite) was in the range of 0.1 to 0.01. This suggests that the optimization of dispersant concentration is required to maximize the iron oxide removal effect with the dispersant injection considering the applied environments, the iron oxide concentration and the concentration ratio of dispersant to iron oxide.

• Journal of Radiation Protection and Research
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• v.30 no.2
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• pp.55-60
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• 2005

The evaluation of neutron flux distribution was performed for the ex-core detector design of SMART-P. DORT and MCNP code were used for the calculation of energy-dependent neutron flux distribution at 100% full power condition. Two code results show that maximum thermal flux appears at the $1^{st}$ water region in IST region and agree within 10% difference. In addition, another evaluation was performed code with assumptions that cote was composed of fission source and control rod without fuel assemblies. These assumptions make neutron count rate to be minimized. As a results, maximum thermal flux showed $6.99{\times}10^{-2}(n/cm^2-sec)$, when the strength of initial fission source was assumed as $1.0{\times}10^8(n/sec)$. The main reason of these results is due to the thermalization of fast neutrons in the water region and thermal flux is proportional to 80% of total neutron flux. Therefore, optimization of filler material of detector guide tube, position of installation and axial length of detector segments is necessary for the design of ex-core detector to enhance the neutron count rate and above results could be used in ex-core detector design as a fluence requirement.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.3
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• pp.51-61
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• 1989

Recently, the growth in the propulsion power and propeller size of typical energy saving ships has resulted in severe damages of the oil-lubricated stern tube bearing. Consequently, a more rational analytical method for the design of the shafting system is required. In this paper an analytical method applicable to the design of the oil-lubricated stern tube bearing and shafting system is presented. The method consists of the finite element analysis of the shafting system and the oil film hydrodynamics. The shafting system is modeled as a three-dimensional problem using beam elements taking account for the steady components of thrust, lateral forces and moments of the propeller as well as the elastic foundation effects. The oil film hydrodynamics is modeled as a two-dimensional problem. Equal and retangular elements employing hourglass control method are used for the construction of the oil film fluidity matrix. To search the quasi-static equilibrium position between the propeller shaft and the oil film, an optimization technique is employed. Some numerical results based on the proposed method are compared with some measured and numerical data available. They show acceptable agreements with the data.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.29-38
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• 2012

The noise generated in the process of obtaining the medical image acts as the element obstructing the image interpretation and diagnosis. To restore the true image from the image polluted from the noise, the total variation optimization algorithm was proposed by the R.O. F (L.Rudin, S Osher, E. Fatemi). This method removes the noise by fitting the balance of the regularity and fidelity. However, the blurring phenomenon of the border area generated in the process of performing the iterative operation cannot be avoided. In this paper, we propose the adaptive total variation method by mapping the control parameter to the proposed transfer function for minimizing boundary error. The proposed transfer function is determined by the noise variance and the local property of the image. The proposed method was applied to 464 tooth images. To evaluate proposed method performance, PSNR which is a indicator of signal and noise's signal power ratio was used. The experimental results show that the proposed method has better performance than other methods.

• Journal of Radiation Protection and Research
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• v.30 no.4
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• pp.185-196
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• 2005

Although medical exposure from diagnostic radiology procedures such as conventional x-rays, CT and PET scans is necessary for healthcare purposes, understanding its characteristics and size of the resulting radiation dose to patients is much of worth because medical radiation constitutes the largest artificial source of exposure and the medical exposure is in a trend of fast increasing particularly in the developed society. Annual collective doses and per-caput effective doses from different radiology procedures in Korea were estimated by combining the effective dose estimates per single medical procedure and the health insurance statistics in 2002. Values of the effective dose per single procedure were compiled from different sources including NRPB reports, ICRP 80, MIRDOSE3.1 code and independent computations of the authors. The annual collective dose reaches 27440 man-Sv (diagnostic radiology: 22880 man-Sv, nuclear medicine: 4560 man-Sv) which is reduced to the annual per-caput effective dose of 0.58 mSv by dividing by the national population of 47.7 millions. The collective dose is far larger than that of occupational exposures, in the country operated 16 nuclear power plants in 2002, which is no more than 70 man-Sv in the same year. It is particularly noted that the collective dose due to CT scans amounts 9960 man-Sv. These results implies that the national policy for radiation protection should pay much more attention to optimization of patient doses in medicine.

• The Transactions of the Korea Information Processing Society
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• v.1 no.4
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• pp.427-437
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• 1994

Optimal static load balancing in star network configurations is considered. Three kinds of load balancing direction strategies are considered. First, a job arriving at the peripheral nodes may be processed either where it arrived(origin node) or transferred directly to central node Second, a job arriving at the central node may be processed there, or transferred to lightly loaded peripheral nodes. A nonlinear optimization problem is formulated. Using the optimal solution, an optimal load balancing algorithm is derived for the second load balancing strategy. Third a job arriving at the central node or a peripheral node may be processed either at origin node or transferred to another lightly loaded node (central or peripheral). A load balancing algorithm is derived for the third load balancing strategy. The effects of these three load balancing strategies are compared by numerical experiments. During the conduct of these in numerical experiments, several interesting phenomena were observed. The third load balancing strategy improved performance more than the first two other strategies. The second load balancing strategy, as a whole, resulted in only slightly improved performance. Finally, of the central node has larger processing power than the peripheral nodes, the first and third load balancing strategies produce equal performance improvement.