• 한국염색가공학회지
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• 제31권4호
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• pp.225-232
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• 2019

The colorants of kale powders were optimally extracted using an 1:1 mixture solvent of ethanol and DMSO at 105℃ for 30 minutes obtaining a high yield of 359.7㎍/mL chlorophylls. Low color fastness of the dyed fabrics with the extracts, particularly against washing and solar radiation, can be overcome by the combined treatments of chitosan, heat setting and tannic acid. Washing fastness to color change was improved from rating 1-2 up to 5 due to the enhanced electrostatic interactions between the colorants and the positive glucosamine unit of the chitosan in the cationized cotton. In addition, the tannic acid treatment contributed to the additional increase in color fastness after the sequential treatments of chitosan pretreatment, dyeing and heat setting.

• Journal of Astronomy and Space Sciences
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• 제27권2호
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• pp.135-144
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• 2010

In this paper, we present the result of preliminary design of tracking mount for ARGO-M which is a movable satellite laser ranging (SLR) system developed by Korea Astronomy and Space Science Institute (KASI). The tracking mount consists of a couple of core parts such as driving motors, encoders and bearings, and the requirements of each parts are determined on the basis of the technical consideration. 2D and 3D models for tracking mount were preliminarily designed using the selected core parts. In order to evaluate the validity of the preliminarily design, the simulator to test the elevation axis was designed and manufactured. The test to check the tracking performance and system accuracy of the simulator was performed, and it was confirmed that the preliminary design meets the operating specifications. Additionally, it was found that the repetitive errors and hysteresis errors need to be improved by the additional control algorithm.

• 한국재료학회지
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• 제15권3호
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• pp.183-188
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• 2005

It was studied in this article how the flexural strength of bare silicon chips is influenced by adopting dual wafer back-lapping process. The experimental results showed that an additional finishing process after the conventional grinding process improves the flexural strength of bare chips by more than 2-fold. In particular, this work showed that the proper removal of the grinding marks$(Ra=0.1\;{\mu}m)$existing on the wafer back-surface resulting from the grinding process significantly contiributes to the enhancement of chip strength.

• Fibers and Polymers
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• 제7권1호
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• pp.1-7
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• 2006

Interaction of a representative antibiotic, doxycycline(Doxy), with commercial poly(acrylonitrile) (PAN) and cationic-dyeable poly(ethylene terephthalate)(PET) fiber was studied in development of infection resistant biomedical materials. Regular PET was also employed for a comparison purpose. Their interactions were investigated at different treatment temperatures, times, and pHs. Fibers were also hydrolyzed by 1% NaOH for 1 or 2 hours at $85^{\circ}C\;and\;100{\circ}C$ to study effect of hydrolysis on antibiotic sorption. Infection-resistant characteristics of the substrates were evaluated by zone of inhibition (ZOI) test. Results revealed that a significant chemical change occurred in PAN and cationic-dyeable PET due to hydrolysis. Additional functional groups obtained by hydrolysis not only enhanced sorption of the antibiotics but also provided greater ZOI values, indicating substantial improvement in sustained infection resistance properties.

• 한국세라믹학회지
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• 제55권2호
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• pp.108-115
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• 2018

The increasing demands for three-dimensional (3D) electronic and optoelectronic devices have triggered interest in epitaxial growth of 3D semiconductor materials. However, most of the epitaxially-grown nano- and micro-structures available so far are limited to certain forms of crystal arrays, and the level of control is still very low. In this review, we describe our latest progress in 3D epitaxy of oxide and nitride semiconductor crystals. This paper covers issues ranging from (i) low-temperature solution-phase synthesis of a well-regulated array of ZnO single crystals to (ii) systematic control of the axial and lateral growth rate correlated to the diameter and interspacing of nanocrystals, as well as the concentration of additional ion additives. In addition, the critical aspects in the heteroepitaxial growth of GaN and InGaN multilayers on these ZnO nanocrystal templates are discussed to address its application to a 3D light emitting diode array.

• 한국표면공학회지
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• 제51권2호
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• pp.133-137
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• 2018

Plasma devices such as jets, pencils, and torches have been developed as new tools that help penetration of target agents and applied to plasma medicine. However, these devices cannot be used in a large area. Therefore, we introduced a flexible plasma device, which can be treated of large area and designed as bendable plasma. In additional, in vitro model based on agarose gel was prepared that can be show effectiveness in the depth of penetration. Plasma treatment conditions such as power, time and distance can be optimized on the agarose gel wound model. The chemical structure of changed polysaccharides was predicted due to reactive excited atoms and molecules, UV photons, charged particles and reactive oxygen and nitrogen species (RONS).

• Journal of Magnetics
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• 제13권4호
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• pp.153-156
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• 2008

We conducted a micromagnetic modeling study to investigate the spin torque oscillator (STO) using a perpendicular polarizer. We used an additional layer of negative anisotropy constant materials (NAM) on a conventional STO. For the NAM layer, the magnetic easy plane is parallel to the in-plane easy axis of the free layer, and inhibits the development of the out-of-plane component of the magnetization in the free layer. As a result, this new type of STO provides a high frequency limit up to 50 GHz.

• 한국세라믹학회지
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• 제43권4호
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• pp.213-219
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• 2006

A Monte Carlo simulation based on Potts model in a three dimensional lattice was studied to analyze and design microstructures in porous sintered compacts such as porosity, pore size, grain (particle) size and contiguity of grains. The effect of surface energy of particles and the content of additional fine particles to coarse particles on microstructure development were examined to obtain fundamentals for material design in porous materials. It has been found that the larger surface energy enhances sintering (necking) of particles and increases contiguity and surface energy does not change pore size and grain size. The addition of fine particles also enhances sintering of particles and increases contiguity, but it has an effect on increment of pore size and grain size. Such a simulation technique can give us important information or wisdom for design of porous materials, e.g., material system with high surface energy and fine particle audition are available for higher strength and larger porosity in porous sintered compacts with applications in an automobile.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2007년도 제28회 춘계학술대회논문집
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• pp.238-241
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• 2007

We present an innovative method of multi-physics application involving energetic materials. Energetic materials are related to reacting flows in extreme environments such as fires and explosions. They typically involve high pressure, hish temperature, strong non-linear shock waves, and high strain rate deformation of metals. We use an Eulerian methodology to address these problems. Our approach is naturally free from large deformation of materials that makes it suitable for high strain-rate multi-material interaction problems. Furthermore we eliminate the possible interface smearing by using the level sets. We have devised a new level set based tracking framework that can elegantly handle large gradients typically found in reacting gases and metals. We show several work-in-progress applications of our algorithm including the Taylor impact test, explosive venting and additional confined explosion problems of modem interest.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1582-1588
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• 2004

The present experimental study aimed to investigate the feasibility of physical water treatment (PWT) devices using catalytic materials to mitigation of crystalization fouling. Two PWT devices having different shape and material were used. The results from microscopic observation and SEM photographs demonstrate that the crystal structure of $CaCO_3$ is Argonite type without water treatment while Calcite type with water treatment, which clearly shows the feasibility of PWT techinque using catalytic materials to mitigate crystalization fouling. For 500 ppm solution, the fouling resistance decreased up to about 23% due to physical water treatment using catalytic materials. The results also reveal that if two more techniques are used simultaneously the additional effects could be expected.