• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.514-522
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• 2007

Finite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this parer, Goel-Okumoto and Yamada-Ohba-Osaki model was reviewed, proposes the Burr distribution reliability model, which making out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE, AIC statistics and Kolmogorov distance, for the sake of efficient model, was employed. Analysis of failure using real data set for the sake of proposing shape parameter of the Burr distribution was employed. This analysis of failure data compared with the Burr distribution model and the existing model(using arithmetic and Laplace trend tests, bias tests) is presented.

• Journal of Korean Philosophical Society
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• v.126
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• pp.25-52
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• 2013

In this thesis, the author will examine how modern philosophical expression manifests in the field of ethics based on Kant's Ethics. The author will critically assess whether Kant's Ethics is an appropriate rational theoretical alternative to overcome today's ecological crisis. In the first section, the author lists the characteristics of modernity. The purpose of this section is to show why Kant's Ethics must be understood in the context of modern age and how his ethics expresses the ideology of the modernity(I). In the second section, the author will analyze the challenge Kant's Ethics face in relation to ecological crisis from the context of dualism between person and thing(II). In the last section, the author will inspect the flaw of Kant's Ethics based on his positive position regarding vicarious duties toward animals, and pose the basic direction of the theory of ecological publicness that can overcome the limits of Kant's Ethics in the context of a critical reconstruction of neo-confucian tradition(III).

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.529-534
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• 2023

Although line printing technology is capable of high-speed and large area printing, residual stresses generated during the manufacturing process can deform the feedhole, causing nozzle plate crack or ink leaks. Therefore, in this paper, we propose a new thermal inkjet print head that is robust, reliable and more suitable for line-printing. The amount of deformation of the conventional line printing head measured through the experiment was converted into an equivalent load, and the validity of the load estimation method was verified through FEA analysis. In addition, in order to minimize deformation without increasing the head size, the head structure was designed to increase internal rigidity by reinforcing the unit nozzle with a pillar or support wall or by adding a support beam or dry/wet etched bridge. The FEA analysis results show that the feedhole deformation was reduced by up to 90%, and it is confirmed that the suggested print head with dry etched feedhole bridge operates normally without nozzle plate cracks and ink leakage through fabrication.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.116-122
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• 2023

As the number of hydrogen filling stations for hydrogen supply increases with the progress of low-carbon eco-friendly energy policies, the risk of accidents is also increasing. Actual pressure vessels may have defects such as notches, pores, and inclusions that may occur during the manufacturing process. Therefore, it is necessary to evaluate the integrity of pressure vessels in the case where cracks exist in pressure vessels under internal pressure. In this paper, 3D finite element analysis was used to evaluate the structural safety of hydrogen-filled pressure vessels with surface cracks, and the shape of surface cracks was compared with the commonly used semi-elliptical shape. In the future, these results will be used to predict the remaining life of the pressure vessel in consideration of fracture mechanics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.482-489
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• 2020

This study conducted a prototype development and evaluation by performing die-casting mold design, mold manufacturing, and injection condition optimization based on flow and solidification analysis to meet the needs of the coupling parts produced by die casting. Through flow analysis, the injection conditions suitable for 100% filling in the cavity were found to be a molten metal temperature of 670 ℃, injection speed of 1.164 m/s, and filling pressure of 6.324~18.77 MPa. In addition, solidification close to 100 % occurred in all four cavities when the solidification rate was 69.47 %. A defect inspection on the surface and inside the product revealed defects, such as poor molding and pores. In addition, the dimensions of the injected product were within the target tolerance and showed good results. Through the feedback of the results of flow and solidification analysis, it was possible to optimize the mold design, and the injection optimization conditions were confirmed to be a total cycle time of approximately 6.5 seconds. Good quality carrier parts with an average surface hardness of approximately 45 mm from the gate measured at 97.48(Hv) could be produced.

• Journal of the Korean Magnetics Society
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• v.10 no.3
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• pp.99-105
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• 2000

One dimensional magneto-photonic crystal having structure of (A/B)$^{k/W}$(B/A)$^{k}$ , where M is a magnetic layer of highly Bi-substituted iron garnet, A and B are dielectric layers of $SiO_2$ and T $a_2$O$_{5/}$, and k is the stacking number of the dielectric layers, has been numerically analyzed as a function of the thickness (d$_{M}$) of M (1∼535 nm) and the stacking numer of k (5∼15). The transmittance, Faraday rotation, and figure of merit of the magneto-photonic crystal have been investigated both in the visible and infrared wavelengths. A factor of several and several tens greater Faraday rotation and figure of merit have been obtained compared to the single layer of M, at many localized modes. In the visible the maximum figure of merit of 0.15 was obtained ( = 720 nm) when k = 11 and d$_{M}$ = 375 nm with T : 0.54, $\theta$$_{F}$ = 8.13$^{\circ}$, which was a factor of 30 greater than that of single garnet layer. Much greater maximum figure of merit, 0.285, was obtained in the infrared ( = 1114 nm) when k = 11 and d$_{M}$ = 800 nm with T = 0.66, $\theta$$_{F}$ = 18$^{\circ}$, which was a factor of 100 greater than that of single garnet layer.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.6
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• pp.25-31
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• 2004

In this paper, we introduce kinetic Monte Carlo (kMC) methods for simulating diffusion process in nano-scale device fabrication. At first, we review kMC theory and backgrounds and give a simple point defect diffusion process modeling in thermal annealing after ion (electron) implantation into Si crystalline substrate to help understand kinetic Monte Carlo methods. kMC is a kind of Monte Carlo but can simulate time evolution of diffusion process through Poisson probabilistic process. In kMC diffusion process, instead of. solving differential reaction-diffusion equations via conventional finite difference or element methods, it is based on a series of chemical reaction (between atoms and/or defects) or diffusion events according to event rates of all possible events. Every event has its own event rate and time evolution of semiconductor diffusion process is directly simulated. Those event rates can be derived either directly from molecular dynamics (MD) or first-principles (ab-initio) calculations, or from experimental data.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.162-173
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• 1996

Dry magnetic particle inspection(MPI) was performed to detect the surface defects of steel ingot cast billets. Magnetic properties of several materials were characterized by the measurement of the B-H hysteresis curve. The inspection results were evaluated in terms of the magnetizing current, temperature, and the amount of magnetic particles applied to billets. Magnetic flux leakage near the defect site of interest was measured and compared with the results of calculation by the finite element method in the case of direct magnetizing current. Direct and alternating magnetizing currents for materials were deduced by the comparison of the inspections. Results of the magnetic particle inspection by direct magnetizing current were compared with those of finite element method calculations, which were verified by measuring magnetic leakage flux above the surface and the surface defects of the material. For square rods, due to the geometrical effect, the magnetic flux density at the edges along the length of the rods was about 30% of that at the center of rod face for a sufficiently large direct magnetizing current, while it was about 70% for an alternating magnetizing current. Thus, an alternating magnetizing current generates rather uniform magnetic flux density over the rods, except for the region on the face across about 10 mm from the edge. The attraction of the magnetic particle by the magnetic leakage field was nearly independent of the surface temperature of the billets up to $150^{\circ}C$. However, the temperature should have been limited below $60^{\circ}C$ for an effective fixing of gathered magnetic particles to the billet surface using methylene chloride. We also found that the amount of applied magnetic particles tremendously affected the detection capability.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.327-332
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• 1999

The recovery activation energy, the order of reaction and the recovery rate constant were detemined by isochronal and isothermal annealing treatment to investigate the recovery behaviors of neutron irradiated Mn-Mo-Ni low alloy steels$(fluence: 2.3\times10^{19}ncm^{-2}, 553K, E\geq1.0 MeV)$. Vickers microhardness tests were conducted to trace the recovery behavior after heat treatments. The results were analyzed in terms of recovery stages, behavior of responsible defects and recovery kinetics. It was shown that recovery occurred through two annealing stages(stage I : 703-753K, stage n : 813-873K) with re$\infty$very activation energies of 2.5 eV and 2.93 eV for each stage I and n, respectively. From the comparison of unirradiated and irradiated isochronal anneal curves, a radiation anneal hardening(RAH) peak was identified at around 813K. Most of recovery have occurred during about 120 min irrespective of isothermal annealing temperatures of 743K and 833K. Recovery rate constants were determined to be $3.4\times10^{-4}min^{-1} and 7.1\times10^{-4}min^{-1}$ for stage I and II, respectively. The order of reaction was about 2 for both recovery stages. Comparing the obtained data with those of previously reported results on neutron irradiated Mn- Mo- Ni steels, the thermal recovery be­havior of the present material seems to occur by the dissociation of point defect clusters formed during irradiation, and by the recombination process of self-interstitials and vacancies from dissociated vacancy clusters.

• Phonetics and Speech Sciences
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• v.16 no.2
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• pp.83-90
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• 2024

This study aimed to explore phonological retrieval and phonological memory skills in second to third graders with dyslexia, poor comprehension, and typical development. The participants included 17 children with dyslexia, 17 children with poor comprehension, and 24 typically developing children. Children with dyslexia scored below 85 on the word decoding test, poor comprehender scored above 90 on the word decoding, and below 85 on the reading comprehension test and typical children scored above 90 on both reading tests. All participants were assessed on rapid automatized naming (RAN) and nonword repetition (NWR). The result indicated that children with dyslexia performed significantly worse on RAN and NWR tasks than other groups. However, there was significant differences between poor comprehender and typically developing children. Furthermore, only RAN were significantly correlated with word decoding and reading comprehension in children with dyslexia. For typically developing children, RAN was correlated with word decoding and reading comprehension, while NWR had a significant correlation with reading comprehension. No correlations were found between these variables for poor comprehender. The finding suggests that children with dyslexia showed difficulties on phonological retrieval and phonological memory, which are essential for reading development while poor comprehender do not have difficulties with phonological processing skills. Phonological processing deficits may underlie word decoding difficulties in dyslexia.