• Smart Structures and Systems
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• v.25 no.2
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• pp.241-254
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• 2020

Using confined shape memory alloy (SMA) bar or plate, this study proposes an innovative self-centering damper. The damper is essentially properly machined SMA core, i.e., bar or plate, that encased in buckling-restrained device. To prove the design concept, cyclic loading tests were carried out. According to the test results, the damper exhibited desired flag-shape hysteretic behaviors upon both tension and compression actions, although asymmetric behavior is noted. Based on the experimental data, the hysteretic parameters that interested by seismic applications, such as the strength, stiffness, equivalent damping ratio and recentering capacity, are quantified. Processed in the Matlab/Simulink environment, a preliminary evaluation of the seismic control effect for this damper was conducted. The proposed damper was placed at the first story of a multi-story frame and then the original and controlled structures were subjected to earthquake excitations. The numerical outcome indicated the damper is effective in controlling seismic deformation demands. Besides, a companion SMA damper which represents a popular type in previous studies is also introduced in the analysis to further reveal the seismic control characteristics of the newly proposed damper. In current case, it was found that although the current SMA damper shows asymmetric tension-compression behavior, it successfully contributes comparable seismic control effect as those having symmetrical cyclic behavior. Additionally, the proposed damper even shows better global performance in controlling acceleration demands. Thus, this paper reduces the concern of using SMA dampers with asymmetric cyclic behavior to a certain degree.

• Journal of the Korea Society for Simulation
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• v.26 no.4
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• pp.43-49
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• 2017

With the advances in and expansion of the semiconductor and display businesses in Korea the demand of the engineers in such fields is increasing. Keeping pace with the trend, the semiconductor courses in undergraduate not only include the newest technologies in addition to the fundamental theories but fabrication related technologies as well in order to produce engineers with practical knowledge. However, since semiconductor fabrication requires expensive equipment and materials in a clean room, laboratory class can't be provided in undergraduate. To overcome this limitation actual fabrication processes are recorded in video and played in class. In addition, 3D visualization of fabrication processes can be used.

• Journal of Digital Convergence
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• v.14 no.10
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• pp.9-16
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• 2016

Along with the development of advanced technology as well as the trend of becoming information society where all different cultures become convergent, communication competence is becoming one of the most important. Therefore, universities are making efforts to open and operate a related curriculum regarding communication competence as the most needed core competence in cultivating competitive men of ability. Accordingly, this study is going to suggest courses and detailed contents for developing communication courses to enhance undergraduates' core competence. The contents of communication subjects include the course outline, objectives, manner of lecturing, evaluation, weekly learning topics, learning objectives, and learning contents, and so on. This study will lay the ground for cultivating undergraduates' communication skills effectively and improving their core competence further to lead their college life soundly based on the understanding of communication. Also, this study will form a field of cultivating competent persons who can create social value through systematic education on communication competence which is the most emphasized as core competence that the members of universities or societies should be equipped with.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.515-519
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• 2015

Complexes composed of hydrogen tetrachloroaurate (III) trihydrate ($HAuCl_4{\cdot}3H_2O$) and DNA were first formed for the synthesis of gold nanoparticle using a DNA template, which were validated using UV-Vis spectroscopy. The morphology of complexes were also characterized by scanning electron microscopy (SEM). DNA-mediated gold nanoparticles were synthesized by the chemical reduction of DNA-Au(III) complexes using hydrazine ($N_2H_4$) and sodium borohydride ($NaBH_4$) as reducing agents. The effects of reducing agent types and their concentration on the formation of gold nanoparticles were investigated. The results showed that hydarazine was the most effective for the reduction of DNA-Au(III) complex. The DNA-mediated gold nanoparticles were characterized SEM, particle size analyzer (PSA), and transmission electron microscopy (TEM). Gold nanoparticles with 55~80 nm in diameter were formed by the aggregation of smaller gold nanoparticles (~nm), which was confirmed in the DNA matrix.

• Transactions of the KSME C: Technology and Education
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• v.4 no.2
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• pp.101-109
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• 2016

The material properties of heat resistant materials at power plants are affected by thermal aging as operating time is accumulated. In this study, the influence of thermal aging on yield strength, tensile strength and fracture behavior for Mod.9Cr-1Mo (ASME Grade 91) steel which is a material widely adopted for Generation IV nuclear energy system has been investigated and analyzed. Service exposed Gr.91 steel materials sampled from a piping system of an ultra-supercritical (USC) plant in Korea with accumulated operation time of 73,716 hours were used for material testing. The test results of the service exposed material specimens were compared with those of the virgin Gr.91 steel specimens. Those test data were compared with the material properties of ASME code and RCC-MRx code. Conservatisms of the material properties in the design codes have been quantified based on the comparisons of those from virgin and service exposed material specimens.

• Information Systems Review
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• v.4 no.1
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• pp.111-130
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• 2002

The Internet is changing or even eliminating old organizational schemes, including education. A growing number of universities and graduate schools are creating curriculums to reflect these changes. Business schools have prepared their students for a corporate world to offer some E-commerce courses. While E-commerce courses are proliferating in computer and information science schools, they are also spreading to other university departments including law and advertising. The objective of this paper is to suggest a prototype E-commerce curriculum for E-commerce departments. First, we survey and compare the E-commerce curriculum offered in many universities. Second, we provide the new E-commerce curriculum model for Korean universities. E-courses are classified as three knowledge areas of E-commerce courses such as business, technology, and core. We prioritize E-courses selected and rank their importance through an exploratory study for suggesting the undergraduate or graduate curriculum.

• Analytical Science and Technology
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• v.25 no.6
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• pp.467-475
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• 2012

A gas chromatography-mass spectrometric (GC-MS) method was developed for determining 17 hazard compounds containing phenols, polycyclic aromatic hydrocarbons and pesticides in surface water. A 1.0 L surface water sample was placed in a separatory funnel and saturated with NaCl, and the solution was extracted with 40 mL of methylene chloride. Under the established condition, the lowest quantification limit was 1.0-10 ng/L and the relative standard deviations were less than 22%. The method was used to analyze 70 surface water samples collected from 35 regions in Gum-River. The samples revealed the compounds concentrations in the range of 1.1-26,604 ng/L. Maximum concentrations of compounds detected were not exceeded guidelines established in other countries. The developed method may be valuable for monitoring hazards in water.

• Journal of Intelligence and Information Systems
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• v.11 no.1
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• pp.1-15
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• 2005

As organizations search fur more secure authentication methods (Dr user access, e-commerce, and other security applications, biometrics is gaining increasing attention. Biometrics offers greater security and convenience than traditional methods of personal recognition. In some applications, biometrics can replace or supplement the existing technology. In others, it is the only viable approach. Several biometric methods of identification, including fingerprint hand geometry, facial, ear, iris, eye, signature and handwriting have been explored and compared in this paper. They all are well suited for the specific application to their domain. This paper briefly identifies and categorizes them in particular domain well suited for their application. Some methods are less intrusive than others.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3682-3687
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• 2009

In this paper, we design and implement watermarking system which create, insert and detect watermark comprised of number or logo to protect copyright and to prevent illegal plagiarism through inserting copyrighting information of owner into the original image. In the proposed system, the number or logo as watermark is selectively inserted according to characteristics of the original contents or requirement of copyrighter. The system also has convenient user interface which general administrator who hasn't expert knowledge for the protection of copyright uses easily. Ownership and copyright protection using digital watermarking technology intensifies creating volition of clients who want to create contents such as cultural contents, Thus, we can expect increasing requests for creating contents such as cultural contents.

• Progress in Superconductivity
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• v.9 no.1
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• pp.80-84
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• 2007

Charcoal was used as a carbon source for improving the critical current density of $MgB_2$ and the effect of annealing temperature on the $J_c$ of $MgB_2$ was investigated. The charcoal powder used in this study was $1{\sim}2$ microns in size and was prepared by wet attrition milling. $MgB_2$ bulk samples with a nominal composition of $Mg(B_{0.95}C_{0.05})_2$ were prepared by in situ process of Mg and B powders. The powder mixture was uniaxially compacted into pellets and heat treated at temperatures of $650^{\circ}C\;-\;1000^{\circ}C$ for 30 minutes in flowing Ar gas. It was found that superconducting transition temperature of $Mg(B_{0.95}C_{0.05})_2$ decreased by charcoal additions which indicates the carbon substitution for boron site. $J_c$ of $Mg(B_{0.95}C_{0.05})_2$ was lower than that of the undoped $MgB_2$ at the magnetic fields smaller than 4 Tesla, while it was higher than that of the undoped sample especially at the magnetic field higher than 4 T. High temperature annealing seems to be effective in increasing $J_c$ due to the enhanced carbon diffusion into boron sites.