• ETRI Journal
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• v.30 no.6
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• pp.833-843
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• 2008

The effect of forward and reverse electrostatic discharge (ESD) on the electro-optical characteristics of oxide vertical-cavity surface-emitting lasers is investigated using a human body model for the purpose of understanding degradation behavior. Forward ESD-induced degradation is complicated, showing three degradation phases depending on ESD voltage, while reverse ESD-induced degradation is relatively simple, exhibiting two phases of degradation divided by a sudden distinctive change in electro-optical characteristics. We demonstrate that the increase in the threshold current is mainly due to the increase in leakage current, nonradiative recombination current, and optical loss. The decrease in the slope efficiency is mainly due to the increase in optical loss.

• Transactions of Materials Processing
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• v.14 no.1 s.73
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• pp.65-70
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• 2005

A phase mixture model was employed to simulate the deformation behaviour of metallic materials covering a wide grain size range from micrometer to nanometer scale. In this model a polycrystalline material is treated as a mixture of two phases: grain interior phase whose plastic deformation is governed by dislocation and diffusion mechanisms and grain boundary 'phase' whose plastic flow is controlled by a boundary diffusion mechanism. The main target of this study was the effect of grain size on stress and its strain rate sensitivity as well as on the strain hardening. Conventional Hall-Petch behaviour in coarse grained materials at high strain rates governed by the dislocation glide mechanism was shown to be replaced with inverse Hall-Petch behaviour in ultrafine grained materials at low strain rates, when both phases deform predominantly by diffusion controlled mechanisms. The model predictions are illustrated by examples from literature.

• Journal of Nutrition and Health
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• v.30 no.10
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• pp.1188-1194
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• 1997

The aim of this was to investigate whether the regular consumption of kimchi influences the iron status (RBC , Hb, Ht, MCH, MCV, MCHC, transferrin , serum iron, and ferritin) in volunteers. Healthy male adults(n=12) took part in the study subdivided into the control Ⅰ-phase(for 2weeks), kimchi-phase (for 4 weeks), and control Ⅱ-phase(for 2 weeks). In addition to their normal diet, participant consumed 300g of lactic acid fermented Chinese cabbage kimchi daily for four weeks. In the control Ⅰ and control Ⅱ phases, the participants kept up their normal diets without consuming any fermented foods. Dietary intakes were recorded for 3 consecutive days in each phase, with the aid of household measures. Every two weeks. blood specimens were analysed. Significant differences(p<0.05) between the phases were found in MCHC, and transferrin in blood were not significantly changed during kimchi consumption. However, serum iron and ferritin levels were significantly increased(p<0.05) during kimchi consumption, achieving the highest levels in the fourth week of the kimchi components(ascrobic acid, sulfer compound, organic acid, capsaicin, gingerol , allicin). Because of lacticacid fermented kimchi's potential to prevent anemia , the consumption of this food can be recommended.

• Journal of Astronomy and Space Sciences
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• v.11 no.1
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• pp.21-30
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• 1994

VV Cep-type long period spectroscopic-eclipsing binary AZ Cas has been observed for five years, 1985 Oct~1990 Feb, UBV at the Ilsan Station of Yonsei University Observatory. A total of 431 observations (U=129, B=142 and V=160) are made for 86 nights. Instrumental differential UBV and B-V light curves made with these observations cover phases nearly a half of one period. There is no appreciable light variation in V but in other two passbands a gradual decrease of the brightness is clearly noticed. The loss of light in B resulted in a reddening in $\Delta(B-V)$ by + 0.06 at phases between 0.4~0.5 as compared with that of at phase ~0.1. This intrinsic reddening arouses a question why at the orbital phase of the transit of a hot star in front of a cool M supergiant the heating of the facing hemisphere of M supergiant by the strong radiation from the B stat is absent. With regard to this unusual situation we propose a hypothesis that a large amount of gas stream of low temperature ejected from the surface of M supergiant component towards the B star dominates the brightness of B star and the reflection effect.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.4 s.148
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• pp.521-528
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• 2006

In this study, we developed a new systematic approach to assess the influence of geometric parameter change on the horizontal and vertical stability indices. To do this, three phases of sensitivity analyses were carried out. First, typical geometric parameters were defined and their effects on hydrodynamic coefficients were assessed by the Sensitivity Analysis (SA) of the indirect method. Second, the effects of hydrodynamic coefficients on the stability indices were calculated. Finally, the sensitivities of geometric parameters on the stability indices were obtained by merging the outputs of two phases using chain rule. The developed approach cau contribute to a submarine designer to determine geometric parameters satisfying pre-requirements about stability systematically.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.374-381
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• 2004

In this study, the deformation behavior of semi-solid Al-Si alloy was investigated by nanoindenter as a part of the research on the surface crack behavior in thixoformed automobile component. The microstructure of semi-solid Al-Si alloy consists of primary and eutectic regions. In eutectic regions the crack initiation begins with initial fracture of the eutectic silicon particles and inside other intermetallic phases. Nano-deformation characteristics in the eutectic and primary phase of semi-solid aluminium alloy were investigated through the nano-indentation experiments and the AFM observation. In addition, mechanical properties of each region were investigated and compared with each other.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.8
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• pp.799-806
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• 2011

This paper proposes an algorithm to detect the stop line and crosswalk on the road surface using edge information and blob coloring. The detection has been considered as an important area of autonomous vehicle technologies. The proposed algorithm is composed of three phases: 1) hypothesis generation of stop lines, 2) hypothesis generation of crosswalks, and 3) hypothesis verification of stop lines. The last two phases are not performed if the first phase does not provide a hypothesis of a stop line. The last one is carried out by the combination of both hypotheses of stop lines and crosswalks, and determines the stop lines among stop line hypotheses. The proposed algorithm is proven to be effective through experiments with various images captured on the roads.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.10
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• pp.49-56
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• 1992

A new global routing algorithm which dynamically adjusts its cost parameters depending on the given routing poroblem to find a near optimum solution has been developed. The proposed algorithm efficiently performs global routing on general area in which all the pin positions are given. This algorithm is composed of two phases`In the first phase, it routes each net by searching a minimum cost path while ignoring the channel capacity. In the second iterative phase, it rips up nets which pass the channel at which the horizontal or vertical routing density exceeds the capacity and then it reroutes them using a modified set of cost parameters. Applying the above phases, paths for nets are found such that routing density doesn't exceed the capacity in each channel and that nets are routed with minimum cost. Experimental results for several benchmark examples including difficult-4, difficult-8, difficult-16, Primary1 and Primary2 show that our method generates better results than other published ones.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.241-249
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• 1982

Two dinnerware porcelain bodies involving partial replacement of feldspar and kaoline by about 35wt% domestic GYUNGJU-pottery stone were developed and their properties such as shrinkage, porosity, firing range, linear thermal expansion, pyroplastic deformation, degree of whiteness and mechanical strength were compared with those of a traditional clay-flint-feldspar body. The experimental results showed that one of the clay-flint-feldspar-pottery stone body with 1% ZnO addition had the firing range of 115$0^{\circ}C$~121$0^{\circ}C$, whereas the traditional body had the firing range of 12$25^{\circ}C$~129$0^{\circ}C$. The linear drying shrinkage and linear dry-to-fired shrinkage of all bodies were 2.5~4.5% and 15~18%, respectively. And the major crystalline phases of sintered bodies were $\alpha$-quartz and secondary mullite surrounded by glassy phases. The modulus of rutpture of sintered bodies was ranged from 860 to 870kg/$\textrm{cm}^2$, and the microhardness of sintered bodies was 680 kg/$\textrm{cm}^2$.

• Journal of Mechanical Science and Technology
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• v.16 no.2
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• pp.175-181
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• 2002

A new polariscope system involving two rotating optical elements and a digital camera for whole field fringe analysis allows automated data to be acquired quickly and efficiently. The developed phase measuring technique that uses eight images through a circular polariscope is presented for the digital measurement of isochromatics and isoclinics, respectively, from photoelastic fringes in a circular disk under diametric compression. Isochromatics can directly be obtained using wrapped isoclinic phases calculated by the arc tangent operator which is the four-quadrant operator from -$\pi$ to $\pi$. It is not required to unwrap isoclinic phases for the calculations of isochromatics. Unwrapped isoclinics are directly determined from isochromatic parameters. Distributions of digitally determined isoclinics are in close agreement to manual measurements. The errors which would appear in unwrapping process of isoclinics can be avoided in the determination of isochromatics.