• Smart Structures and Systems
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• v.16 no.4
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• pp.641-665
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• 2015

In this paper, a simple and efficient phenomenological macroscopic one-dimensional model is proposed which is able to simulate main features of shape memory alloys (SMAs) particularly ferro-elasticity effect. The constitutive model is developed within the framework of thermodynamics of irreversible processes to simulate the one-dimensional behavior of SMAs under uniaxial simple tension-compression as well as pure torsion+/- loadings. Various functions including linear, cosine and exponential functions are introduced in a unified framework for the martensite transformation kinetics and an analytical description of constitutive equations is presented. The presented model can be used to reproduce primary aspects of SMAs including transformation/orientation of martensite phase, shape memory effect, pseudo-elasticity and in particular ferro-elasticity. Experimental results available in the open literature for uniaxial tension, torsion and bending tests are simulated to validate the present SMA model in capturing the main mechanical characteristics. Due to simplicity and accuracy, it is expected the present SMA model will be instrumental toward an accurate analysis of SMA components in various engineering structures particularly when the ferro-elasticity is obvious.

• KIEAE Journal
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• v.15 no.6
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• pp.69-80
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• 2015

Purpose: Since most simulation programs take the interface that lists up all the input variables representing all the functionalities, users must know where design variables of an Energy Conservation Measure (ECM) are located and also know what values are appropriate. This is why practitioner designers feel frustrated when they attempt to use simulation. The final objective of this study is to provide a building energy modeling guideline for practitioners in various fields such as architectural design and MEP. Method: As the first step of the modeling guideline, this study provides the Level of Detail (LOD) for simulation modeling of primary ECMs considering the design information available in each design phase. It is prepared by literature review, simulation functionality investigation, and field experts' survey. Result: The proposed simulation LOD offers a milestone at each design phases concerning what design variable and attributes need to be developed with how much of details in order to meet the project goal. Also each design team can set up a simulation usecase considering organizational characteristics based on the proposed LOD.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.232.2-232.2
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• 2015

Piezoelectric force microscopy (PFM) is a powerful method to characterize inversed piezoelectric effects directly using conductive atomic force microscopy (AFM) tips. Piezoelectric domains respond to an applied AC voltage with a characteristic strain via a contact between the tip and the surface of piezoelectric material. Electroactive piezoelectric polymers are widely investigated due to their advantages such as flexibility, light weight, and microactuation enabling various device features. Although piezoelectric polymers are promising materials for wide applications, they have the primary issue that the piezoelectric coefficient is much lower than that of piezoelectric ceramics. Researchers are studying widely to enhance the piezoelectric coefficient of the materials including nanoscale fabrication and copolymerization with some materials. In this report, nanoscale electroactive polymers are prepared by the electrospinning method that provides advantages of direct poling, scalability, and easy control. The main parameters of the electrospinning process such as distance, bias voltage, viscosity of the solution, and elasticity affects the piezoelectric coefficient and the nanoscale structures which are related to the phase of piezoelectric polymers. The characterization of such electroactive polymers are conducted using piezoelectric force microscopy (PFM). Their morphologies are characterized by field emission-scanning electron microscope (FE-SEM) and the crystallinity of the polymer is determined by X-ray diffractometer.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.6 no.1
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• pp.78-82
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• 2010

The feeder pipe of Main Primary Heat Transfer System in Wolsong Nuclear Power Plant was inspected by the Ultrasonic Phase Array technique in 2010. It is the first time to apply this method to the construction at Nuclear Power Plant in Korea. The time required for UT technique is less than RT method. The UT method doesn't need to evacuate personnel who works nearby inspecting area and doesn't need to wait developing of film. For these reasons, the UT method is the fastest method among the volumetric inspections. As a result of the examination, it became clear that main defect of the feeder pipe is the Lack of fusion in the welded area. Moreover, the rate of defect was reduced gradually as improvement of welder's skill. If welding machine has problem, the defect has tended to same pattern(occurred same position in the welding area) but these defects were founded without specific rules. For these reasons, the creation of defect is dependent on the skill of worker not on the automatic welding machine. This evaluation of defect signal and collecting data would be useful to further examination in ISI.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.317-322
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• 2003

A novel three-level DC/DC converter (TLC)for high power applications operating from high input voltage Is proposed. Its switch voltage stress can be ensured to be only one-half of the Input voltage. Nevertheless, since all input voltage is applied to the transformer primary side, it has good turns ratio. The driving method of each module is same as those of the conventional phase-shifted ZVS full bridge PWM converter (PSFB) and the zero-voltage-switching (ZVS) of the leading leg are achieved exactly in the same manner as that of the PSFB. Moreover, its three-level operation can considerably reduce the current ripple through the output inductor and it has no problems of the DC-link voltage unbalance. Therefore, it features a low voltage stress, high efficiency, low EMI, high power density, and small sized filter. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200W, 600V/DC-48V/DC prototype are presented.

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.21-28
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• 2011

The primary purpose of the present study was to investigate the mechanism causing scour around a pipeline placed on the seabed in a shallow water zone. Such submarine pipelines are usually exposed to currents and waves. The present experiments made estimates for each different flow type. The scour width and depth in the equilibrium scour phase were analyzed by non-dimensional parameters. The experiment in this study considered various parameters: pipe diameters, wave periods, wave heights, and current velocities. Using the experimental results, the correlations of scour width, scour depth, and main non-dimensional parameters such as the Fr number and KC number were analyzed. In the case of steady currents, the scour hole was closely related to the bottom velocity, while the scour hole in waves showed a relatively low correlation to the bottom velocity because when exposed to waves the scour hole was restricted according to the movement distance of the water particles during a wave period. However, the scour width under a steady current was not limited because vortex shedding was well developed from having enough time and distance.

• Journal of the Korea Fashion and Costume Design Association
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• v.4 no.1
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• pp.143-153
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• 2002

Fashion has been analyzed and explained in diverse ways. Fashion, like every phase of culture, is a reflection of the Zeitgeist. In order to understand the changing fashion we must understand the changing society. For fashion of a period are expressions of the interrelation of the various elements of the culture, including the social and political values, the economic and industrial progress, art, the development of technology, etc... Particularly fashion is closely connected with a style of art. In a style of art, futurism focused on the "dynamism" resulting from super-speed and high-technology. This study aimed to review literatures, fashion magazines, web-site in order to know how the dynamism of futurism is expressed in modern fashion. The results of this study were as follows; 1. Dynamism was expressed by means of lines, colors, patterns through the eyesights visually. Asymmetrical oblique lines, zig-zag lines or bold cutting expressed the mechanical and offensive dynamism. In contrast, such lines as curves and spirals expressed the soft and natural dynamism. Primary colors or complementary contrast expressed energetic and rhythmical dynamism. The geometrical patterns and automobile wheels patterns expressed dynamism resulting from mechanical aesthetics. 2. Dynamism was expressed through repeat of lines, colors, patterns, and textiles. Particularly Vinyl material, fluorescent material, metallic material, beads, and spangle expressed a strong dynamism. On the other hand, natural materials, paper and other similar ones are used to signify the orientation towards a futuristic high-technology society.y society.

• Child Health Nursing Research
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• v.13 no.3
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• pp.308-317
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• 2007

Purpose: The purpose of this study was to develop a MOL instrument for school-age children in grades 4 through 6. Method: The research design was a methodological study. A four-phase design involved. 1) Interview data generated from professors, nurses, and elementary school students (n=8). 2) Content validation by expert panel (n=14) 3) Initial items corrected by elementary school students (n=20) 4) Instrument validation by survey (n=574). Finally, 24 items were chosen as a meaning of life scale for late school-age children. Results: The Cronbach's alpha coefficient of 24 items was .893 indicated a high internal consistency of the instrument, 2) Through factor analysis, 5 factors were extracted. These factors were labeled as 'relational experience', 'positive attitude', 'satisfaction/ hope', 'pursuit of goal', and experience of family love. These factors explained 52.311% of the total variance. Conclusion: The MOL scale for late school-age children can be used in nursing programs to improve the meaning of life. Studies on difference in meaning of life for late school-age children are needed for reverification.

• KSBB Journal
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• v.27 no.4
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• pp.232-236
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• 2012

Comparative liquid chromatographic enantiomer separation of ${\alpha}$-amino acids, their esters and primary amino compounds was performed using two chiral stationary phases (CSPs) prepared by covalently bonding (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) of the same chiral selector. In general, the separation factors and resolution factors for these analytes on CSP 1 were greater than on CSP 2, while these capacity factors on CSP 2 were quite greater than on CSP 1. Except for leucine methyl ester and phenylalanine methyl ester, the elution orders of all analytes including ${\alpha}$-amino ${\alpha}$-alkyl acids and phenylglycine alkyl esters on CSP 1 are identical to those on CSP 2. This study showed that different connecting structures for these two CSPs might influence their ability to resolve the analytes depending on their structures related to the chiral recognition mechanism.

• BMB Reports
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• v.42 no.12
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• pp.806-811
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• 2009

Recently, various phenolic acid phenethyl ureas (PAPUs) have been synthesized from phenolic acids by Curtius rearrangement for the development of more effective anti-oxidants. In this study, we examined the anti-tumor activity and cellular mechanism of the synthetic compound (E)-1-(3,4-dihydroxyphenethyl)-3-styrylurea (PAPU1) using melanoma B16/F10 and M-3 cells. Results showed that PAPU1 inhibited the cell proliferation and viability, but did not induce cytotoxic effects on primary cultured fibroblasts. PAPU1 induced apoptotic cell death rather than necrosis in melanoma cells, a result clearly proven by the shift of cells into sub-$G_1$ phase of the cell cycle and by the substantial increase in cells positively stained with TUNEL or Annexin V. Collectively, this study revealed that PAPU1 induced apoptosis in a caspase-dependent manner, suggesting a potential role as a cancer chemopreventive agent for melanoma cells.