• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1158-1162
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• 2009

Fatigue limit of the copper film coated by Sn was estimated using Goodman diagram and Gerber diagram. To obtain the high cycle fatigue life curve, S-N curve, of the film, the high cycle fatigue test was carried out by applying the constant amplitude load to the film specimen with three different stress ratio of 0.05, 0.3 and 0.5 and the frequency of 40 Hz at room temperature in air. The free-standing film specimen 15.26${\mu}m$ thick was fabricated by etching process. The fatigue limits and S-N curves at the respective stress ratios were determined from the experimental works. It was shown that the S-N curves were dependent on the stress ratio and the fatigue limit was increased with decreasing the stress ratio. The dependency of the fatigue behavior was presented in empirical relationship. Using these relationships, the fatigue limit was predicted.

• Journal of Astronomy and Space Sciences
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• v.22 no.3
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• pp.233-242
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• 2005

The absolute dimensions and orbital elements of 66 near contact binaries, collected from literatures, have been analyzed to investigate the physical characteristics of the near contact binaries as well as co-relations among physical parameters. The relationship between the mass ratio and luminosity ratio of the near contact binary systems have been obtained as a $L_2/L_1{\approx}(M_2/M_1)^{1.45}$, which is similar to that of the early type contact binary system. The physical parameters of the new contact binaries show that the difference in mass, radius, luminosity and temperature between the primary and the secondary components for the F type NCBs are smaller than those for the A type NCBs. In H-R diagram, the components of the A types are located closer to the terminal age main sequence than those of the F types.

• Journal of The Korean Astronomical Society
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• v.22 no.1
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• pp.63-79
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• 1989

Current estimates, based on the same star-count analysis, of the distance to the globule Bamard 361 range from 300 pc to 650 pc. All the problems associated with the estimates have been fully rectified in this study, and a modification has been made to the classical Wolf diagram to improve the accuracy in the distance determination. A reference field was carefully selected close to the globule but well outside the globule boundary, and star counts for this field were performed on the blue POSS plate in order to set up the reference magnitude sequence appropriate to the general area of B 361. From the reference sequence, the stellar density function has been derived specifically for the direction toward the globule. Correction was made for the general interstellar extinction, and the luminosity function with the Wielen's dip was adopted. The resulting density function clearly reveals the existence of the local Cygnus-Orion arm in the direction of B 361 at about 700 pc away from the Sun. Analysis of the star-count data for the program field locates the globule at distance $600{\pm}50$ pc ; thus, the globule is an object located in the Cygnus-Orion arm, residing somewhat toward its leading edge.

• Resources Recycling
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• v.27 no.3
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• pp.3-7
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• 2018

Development of extractive metallurgical processes for metal sulfides has become of importance owing to the depletion of oxide ores with rich metal contents. Most of the leaching reactions of metal sulfides is electrochemical reaction and can be classified as $H_2S$, S, and ${SO_4}^{2-}$ evolution type. The acidity of leaching solution and the presence and concentration of an oxidizing agent affect the formation of reaction intermediates containing sulfur. Frost diagram of sulfuroxoanion indicates that the oxoanions with higher oxidation number are more thermodynamically stable in the presence of oxidizing agents.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.258-261
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• 2007

Failure phenomena in uni-axial tension test were experimentally and numerically investigated for AA6111-T4, AA5083-H18 and DP-Steel, which were friction-stir welded with the same and different thicknesses. Forming limit diagram(FLD) was measured using hemispherical dome stretching tests for base materials and also predicted by Hill's bifurcation and M-K theories for welded areas. Finite element simulations well predicted hardening behaviors, failure locations as well as failure patterns for the uni-axial tension tests especially utilizing very fine meshes and FLD along with stress softening.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.66-70
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• 2008

In this study, the formability of AZ31B magnesium alloy sheets was investigated by the analytical and experimental approaches. Tensile tests and limit dome height tests were rallied out at several temperatures between $25^{\circ}C$ and $300^{\circ}C$ to obtain the mechanical properties and forming limit diagram (FLD). The FLD-based criterion considering the strain-path and the blank temperature was used to predict the forming limit in a deep-drawing process of cross-shaped cup by finite element analysis. This criterion proved to be very useful in determining the optimal process conditions such as blank shape, punch velocity, minimum comer radius, fillet size, and so on, through the comparison between FEA and experimental data. In particular, the temperature of each tool that provided the best formability of the blank was determined by coupled temperature-deformation analyses. A practical method that can greatly reduce the forming time by increasing the punch speed during the forming process was suggested.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.3
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• pp.71-82
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• 1999

Irregular motions of nonlinear dynamic system are the result of an intrinsic characteristics that the system have, and sometimes occur unpredictable large motion. For a ship in a regular seaway, the capsizing occur because of this unexpectable motion. So, from the safety's point of view, nonlinear ship motions should be treated carefully. In this study, stable and unstable regions are investigated firstly under the variation of a control external force. Secondly, we consider the attractors to know how ship motions of the stable region that does not undergo capsizing change. Thirdly, bifurcation diagram is considered to study the range in detail where nonlinear chaotic motions are occurred.

• Journal of Korean Society for Quality Management
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• v.30 no.1
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• pp.1-21
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• 2002

The purpose of this study was to empirically examine the customer oriented quality creation by considering quality elements required by customers in the product design process. The study tried to extract attractive quality elements by using Kano's model. After identifying the elements HOQ(the house of quality) of QFD(quality function deployment) was used to identify the trend of quality elements evaluation. Test for equal means (t-test) was applied to verify the attractive quality elements of adult shoes. It made us find the customer oriented quality elements from the customer needs and latent dissatisfaction. We collected the opinions of experts on shoes and complete the cause and effect diagram and affinity diagram (KJ method). The data of the questionnaire was put to the QFD and the contents of quality elements was identified by brain storming method. We calculated indexes which were the multiplication of weight and marks of quality elements in the cross table of the HOQ by QFD. Then we tested for the equality of means between the indexes and the sum of attractive quality elements. The results for equal means were statistically significant. To create the customer quality the product design should be differentiated between the age groups over attractive quality elements.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.1
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• pp.37-45
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• 2015

As of June 2014, the rate of mobile internet users aged 6 and over is estimated at 98.3% (up by 2.8%p from the previous year). The vast majority of the teens (99.7%), the 20s (99.8%), the 30s (99.8%), and the 40s (98.1%) answer they use the smart phone. The existing notice methods have utilized noticeboard in the apartment. It is difficult to support real-time notice. The App has a merit to be accessed in anywhere, so that it is quite suitable for services requiring real-time support. This paper describes a development of apartmenrt notice and decision-making service using smart phone. We study previous researches about apartmenrt notice Apps. Then, we described the notice flow diagram and decision-making flow diagram. Apt admin sends the important notice message to residents using apt notice app in real-time. Apt admin writes the decision item in the admin web site. It pushes decision item to residents using apt notice app in real-time. The residents vote and send it to Apt admin. Apt admin counts the votes and send the collect the vote result to to residents.

• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.304-308
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• 2007

Failure phenomena in uni-axial tension test were experimentally and numerically investigated for AA6111-T4, AA5083-H18 and DP-Steel, which were friction-stir welded with the same and different thicknesses. Forming limit diagram(FLD) was measured using hemispherical dome stretching tests for base materials and also predicted by Hill's bifurcation and M-K theories for welded areas. Finite element simulations well predicted hardening behaviors, failure locations as well as failure patterns for the uni-axial tension tests especially utilizing very fine meshes and FLD along with stress softening.