• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.1-7
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• 2018

A folding solar power system is a stand-alone system and is a structure with solar panels attached. It consists of supporting parts and folding parts for ease of movement. While the efficiency of solar panels is also important to produce electricity by maximizing the power efficiency of solar panels, the most important thing is structure stability. The folding solar power structure intended to be developed in this study is a collapsible structure that is easy to move and install into systems that can produce electricity from grid to independent. Since these structures are installed outdoors, wind loads, snow cover, etc. In this paper, the wind loads most affected by the folding solar power generation structure were obtained using the MeshFree Finite Element Method. MeshFree is a program that makes it easier for users to interpret by simplifying the mesh tasks required by an existing analysis. The analysis showed that the greater the angle of inclination of the wind to the ground, the greater the wind load. In addition, reliability was ensured by wind load testing.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.41-47
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• 2020

The effect of Co interlayer on the interfacial reliability of SiN_x/Co/Cu thin film structure for advanced Cu interconnects was systematically evaluated by using a double cantilever beam test. The interfacial adhesion energy of the SiN_x/Cu thin film structure was 0.90 J/㎡. This value of the SiN_x/Co/Cu thin film structure increased to 9.59 J/㎡.Measured interfacial adhesion energy of SiN_x/Co/Cu structure was around 10 times higher than SiN_x/Cu structure due to CoSi₂ reaction layer formation at SiN_x/Co interface, which was confirmed by X-ray photoelectron spectroscopy analysis. The interfacial adhesion energy of SiN_x/Co/Cu structure decreased sharply after post-annealing at 200℃ for 24 h due to Co oxidation at SiN_x/Co interface. Therefore, it is required to control the CoO and Co₃O₄ formation during the environmental storage of the SiN_x/Co/Cu thin film to achieve interfacial reliability for advanced Cu interconnections.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.45-51
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• 2015

In this paper, we study the RF characteristics of the short wavelength thin-film transmission line employing microstrip line (ML)/coplanar waveguide (CPW) composite structure on silicon substrate for application to RFIC (radio frequency integrated circuit). The thin-film transmission line employing ML/CPW composite structure showed a wavelength shorter than conventional transmission lines. Concretely, at 10 GHz, the wavelength of the transmission line employing ML/CPW composite structure was 6.26 mm, which was 60.5 % of the conventional coplanar waveguide. We also extracted the bandwidth characteristic of the transmission line employing ML/CPW composite structure using equivalent circuit analysis. The S parameter of the equivalent circuit showed a good agreement with measured result. According to the bandwidth extraction result, the cut-off frequency of thin-film transmission line employing ML/CPW composite structure was 377 GHz. Above results indicate that the transmission line employing ML/CPW composite structure can be effectively used for application to broadband and compact RFIC.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.1
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• pp.9-18
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• 2016

The slender structures such as high rise building or marine riser are highly susceptible to dynamic force exerted by fluid-structure interactions among which vortex-induced vibration(VIV) is the main cause of dynamic unstability of the structural system. If VIV occurs in natural frequency regime of the structure, fatigue failure likely happens by so-called lock-in phenomenon. This study presents the numerical analysis of dynamic behavior of both structure and fluid in the lock-in regimes and investigates the subjacent phenomena to hold the resonance frequency in spite of the change of flow condition. Unsteady and laminar flow was considered for a two-dimensional circular cylinder which was assumed to move freely in 1 degree of freedom in the direction orthogonal to the uniform inflow. Fluid-structure interaction was implemented by solving both unsteady flow and dynamic motion of the structure sequentially in each time step where the fluid domain was remeshed considering the movement of the body. The results show reasonable agreements with previous studies and reveal characteristic features of the lock-in phenomena. Not only the lift force but also drag force are drastically increasing during the lock-in regime, the vertical displacement of the cylinder reaches up to 20% of the diameter of the cylinder. The correlation analysis between lift and vertical displacement clearly show the dramatic change of the phase difference from in-phase to out-of-phase when the cylinder experiences lock-in. From the results, it can be postulated that the change of phase difference and flow condition is responsible for the resonating behavior of the structure during lock-in.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.2
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• pp.99-103
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• 2010

Waxes, or long-chain hydrocarbons, may be obtained naturally from animals, vegetables, and mineral waxes, or may be synthesized. The oil-wax gels are widely applied to lots of cosmetics such as lipsticks. For example, the lipstick texture is strongly dependent on the glossiness of the oil-wax gels. Extensive research has been carried out to investigate the lattice structure of wax mixture in pure solvents (hydrocarbons) and defined mixtures. However, only a limited amount of work has been published on the lattice structure of wax matrixes in undefined mixtures. The objective of this study was to investigate the relationship between the lattice structure of ceresin wax and different wax mixtures and the glossiness of oil-wax gels. Recently visual factors such as the glossiness of skin are generally known as the words to express the beauty. The mechanism of glossiness has been suggested to understand the changes that occur in the lattice structure of the wax matrixes when they are forming gels and also the effects of the nature of solvent. The present work investigates the lattice structure of the wax matrixes and glossiness of oil-wax gels obtained from ceresin and microcrystalline wax as well as of the gels formed by different waxes in solvent.

• The Journal of Fisheries Business Administration
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• v.40 no.1
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• pp.27-49
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• 2009

Recently, the Korea's economy concerns the second money crisis because of the rapid increase of the exchange rate. The Korea's economy which is very dependent on the foreign trade is more sensitive to the change of exchange rates. There are many literatures which analyze the effects of variations of the exchange rates on the secondary and tertiary industries such as the manufacturing industry and IT(Information Technology). But there have been no studies which try to figure out the effects of variations of exchange rate on the primary industries, especially, fisheries' industry. Therefore this paper tries to analyze the effect of price competition structure and the change of exchange rate on foreign fisheries exporting prices in Korea's fisheries import market. This study utilizes OLS(Ordinary Least Squares Analysis) for the analysis in the market of frozen yellow corvina, hairtail, angler fish which are major fisheries importable in Korea. The results show that the exporting country which has the highest market share is more sensitive to the change of the exchange rates itself than that of the other exporting countries' price when it starts to set up its exporting price. And the exporting countries which have low market share are more sensitive to the change of price which country has the highest market share than that of price whose countries have low market share and those of their exchange rate. Also we can find out that the countries which have similar market share try to set up price-setting strategy in the opposite direction. In other words, one country tries to bid up its price, other countries response to rival country by lowering their prices. In the consideration of the fact that most exporting countries aren't affected by Korea's fisheries' prices, the exporting countries in Korea's fisheries import market are more sensitive to the prices of other exporting countries than that of Korea's. This result indicates that the price leader-follower model could be applicable to the Korea's fisheries import market.

• Journal of the Korean Society of Earth Science Education
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• v.4 no.3
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• pp.205-217
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• 2011

This study analyzed the reading materials presented in the existing 'Experiment Observation' targeting 31 elementary school students and conducted a preliminary investigation to examine the cause which makes the science reading materials of elementary school difficult to read. Also, on the basis of a preliminary investigation, this study developed the reading materials on science. After that, by examining the degree of understanding about existing reading materials on 'Experiment Observation' targeting 55 students of elementary schools and the newly developed reading materials targeting 44 students of elementary schools, the study proved its effect. As the result of the study, the causes for which students felt difficulty in reading were as follows: the scientific or non-scientific terms were explained by using more higher levels of Chinese characters compared to the levels of students; the scientific terms never treated in the classroom were used in the reading materials without any explanation; the overall structure of existing reading materials was distracted and listed the fragments of information, and the sentences were described complicatedly; the contents of a text and the photo materials were not connected functionally. In addition, the newly developed science reading materials were preferred by students because more various methods were devised, such as more systematic structure, arrangements of simpler sentence structure, additional explanation of scientific terms, divisions of paragraphs and postscript and their understanding was found to be improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.358-358
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• 2012

The application of BZO (Boron-doped Zinc Oxide) films use as the TCO(Transparent Conductive Oxide) material for display and solar cell industries, where the conductivity of the BZO films plays a critical role for improvement of cell performance. Thin BZO films are deposited on glass substrates by using RF sputter system. Then charging flow rates of O2 gas from zero to 10 sccm, thereby controlling the impurity concentration of BZO. BZO deposited on soda lime glass and RF power was 300 W, frequency was 13.56 MHz, and working pressure was $5.0{\times}10-6$ Torr. The Substrate and glass between distance 200 mm. We measured resistivity, conductivity, mobility by hall measurement system. Optical properties measured by photo voltaic device analysis system. We measured surface build according to oxygen flow rate from XPS (X-ray Photoelectron Spectroscopy) system. The profile of the energy distribution of the electrons emitted from BZO films by the Auger neutralization is measured and rescaled so that Auger self-convolution arises, revealing the detail structure of the valence band. It may be observed coefficient ${\gamma}$ of the secondary electron emission from BZO by using ${\gamma}$-FIB (Gamma-Focused Ion Beam) system. We observed the change in electrical conductivity by correlation of the valence band structure. Therefore one of the key issues in BZO films may be the valence band that detail structure dominates performance of solar cell devices. Demonstrating the secondary electron emission by the Auger neutralization of ions is useful for the determination of the characteristics of BZO films for solar cell and display developments.

• Journal of the Korean Electrochemical Society
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• v.3 no.2
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• pp.85-89
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• 2000

For replacing Li metal at Lithium ion Battery(LIB) system, we used carbon powder material which prepared by Pyrolysis of Phenol resin as starting material. It became amorphous carbon by Pyrolysis through it's self condensation by thermal treatment. Amorphous carbon can be doped with Li intercalation and deintercalation because it has wide interlayer. However, it has a problem with structural destroy due to weak carbon-carbon bond. So, we used $ZnCl_2$ as the pore-forming agent. This inorganic salt was used together with the resin serves not only as the pore-forming agent to form open pores, which grow into a three-dimensional network structure in the cured material, but also as the microstructure-controlling agent to form a loose structure doped with bulky dopants. We used SEM in order to find to difference of structure, and can calculate the distance of interlayer by XRD analysis. CV test showed oxidation and reduction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.175-183
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• 2014

This study investigates the response of structures to tunnelling-induced ground movements in clay ground, varying tunnel excavation condition (tunnel depth and diameter), tunnel construction condition (ground loss), and tunnel ground condition (soft clay and stiff clay). Four-story block-bearing structures have been used because the structures can easily be characterized of the extent of damages with crack size and distribution. Numerical parametric studies have been used to investigate of the response of structures to varying tunnelling conditions. Numerical analysis has been conducted using Discrete Element Method (DEM) to have real cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The results of structure responses from various parametric studies have been integrated to consider tunnel excavation condition, tunnel construction condition, and tunnel ground condition and provide a relationship chart among them. Using the chart, the response of structures to tunnelling can easily be evaluated in practice in clay ground.