• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.392-393
• /
• 2007

In this paper, we report the characteristics inorganic EL device with high dielectric constant materials of PMN, PZT. Fabricated EL device shows stable light emission even at 20kHz -400Volt without any break down failure. Brightness voltage curve of EL device is same with typical EL. As increasing applied voltage, the brightness increased linearly. From the results of Frequency and duty ratio variation, over 50% of brightness increment was seen. Luminous efficiency was increased upto 200V range and saturated over 200V by slow increasement of light emission. We got e bright stable emission of 1733 cd/m2 at the condition of Frequency 35 KHz, Duty 10%, 400V.

• Transactions on Electrical and Electronic Materials
• /
• v.14 no.2
• /
• pp.63-66
• /
• 2013

This paper describes the highly productive process technologies of microprobe arrays, which were used for a probe card to test a Dynamic Random Access Memory (DRAM) chip with fine pitch pads. Cantilever-type microprobe arrays were fabricated using conventional micro-electro-mechanical system (MEMS) process technologies. Bonding material, gold-tin (Au-Sn) paste, was used to bond the Ni-Co alloy microprobes to the ceramic space transformer. The electrical and mechanical characteristics of a probe card with fabricated microprobes were measured by a conventional probe card tester. A probe card assembled with the fabricated microprobes showed good x-y alignment and planarity errors within ${\pm}5{\mu}m$ and ${\pm}10{\mu}m$, respectively. In addition, the average leakage current and contact resistance were approximately 1.04 nA and 0.054 ohm, respectively. The proposed highly productive microprobes can be applied to a MEMS probe card, to test a DRAM chip with fine pitch pads.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.42-43
• /
• 2006

LTCC 후막공정에서 일반적으로 사용되고 있는 스크린 프린팅 방법은 낮은 정밀도와 100um 이하의 선폭을 구현하는 데 한계를 보이고 있다. 이에 따라서 보다 미세한 라인을 형성 할 수 있는 반도체 미세라인 공정기술을 후막 공정에 응용한 후막 리소그라피 기술 (thick-film lithography technology)이 전자부품의 소형화에 대한 방안으로 연구 되고 있다. 본 연구에서는 후막 리소그라피 기술에 사용되는 감광성 Silver 페이스트에 영향을 미치는 각기 다른 크기와 형상의 Silver 파우더들과 인쇄 후 표면의 roughness 개선을 위한 여러 종류의 첨가제들을 첨가하여 최적의 조성을 연구 하였으며, 그린시트와 페이스트의 매칭성을 해결하기 위해서 Tg가 다른 글라스 파우더를 첨가하였다. 또한 전면 인쇄 한 후에 건조, 노광, 현상, 적층, 소성 과정을 걸치는 후막 리소그라피 기술을 이용하여 소성 후 20um이하의 선폭을 가지는 내장형 패턴 구현하였으며 투과엑스레이와 O/S 테스트 통하여 우수한 특성을 확인 할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.271.1-271.1
• /
• 2013

Titania is usually used in sun-screens, tooth paste, and other daily used objects as a pigment. However, scientists have focused on titania as photocatalyst due to its excellent activities. By fabricating vanadium doped TiO2 and CuOx co-catalyzed TiO2 nano-size filter, the degradation level of the volatile organic compound (VOC) concentration was tested using 365nm UV LED as light source in a closed chamber. Main purpose for this test is to evaluate the activities of various catalysts for degrading the VOCs which are detrimental to human body and toluene and p-xylene were chosen in the VOC removal test. Target gas materials were injected into the test chamber with dry air as carrier gas which was flowed into the gas washer bottle filled with liquid form of VOC substance. When the VOC gas flows into the chamber, it is circulated by 200 mm fan in order to contact with the set-up filter on the aluminum holder. Target gas concentration in the chamber was monitored using VOC detector (miniRae3000, Raesystems) which was also placed inside the chamber. With the measured concentration, the VOC degradation efficiency and the degradation rate were evaluated and used to compare the catalytic activities.

• Bulletin of the Korean Chemical Society
• /
• v.11 no.3
• /
• pp.200-205
• /
• 1990

Chemically modified electrodes(CMEs), based on 2-imino-1-cyclopentane-dithiocarboxylic acid (icdc) containing carbon paste, have been characterized using cyclic voltammetric techniques. Ag(I) was chemically deposited on the CMEs, and voltammograms were obtained with the electrode in a separate buffer solution. The CME surface can be regenerated with exposure to acid and reused for deposition. In 10 deposition/measurement/regenerate cycles, the linear response have been reproduced up to $1{\times}10^{-6}$ M in linear sweep voltammetry and 1${\times}$10-8 M in differential pulse voltammetry with relative standard deviation of 5.2% and 12.4%, respectiveiy. The sensitivity increased with deposition time and scanning rate, and detection limit was $1{\times}10^{-7}M\;and\;1{\times}10^{-9}M$ at 20 minutes deposition in the linear sweep voltammetry and differential pulse voltammetry, respectively. The presence of some metal ions does not influence the silver ion response. Satisfactory results were obtained for the analysis of the silver ion for a variety of reference materials without interference of Hg ion at the condition of pH = 5-6.

• Natural Product Sciences
• /
• v.27 no.2
• /
• pp.115-121
• /
• 2021

Lentinus edodes contains functional metabolites such as polysaccharopeptides, lectins, and secondary metabolites. Fermented soybean paste is representative fermented materials in Korea, and is gradually increasing due to various biological activities. In the present study, ethanol extracts of fermented products with/without L. edodes were designated as SPL and SP, and prepared to develop safer and therapeutic functional foods with antioxidant and anti-inflammatory activities for treatment of inflammatory disorders. SP and SPL extracts exhibited antioxidant effects via inhibiting radical activities. Inflammatory mediators, nitric oxide (NO), prostaglandin E₂ (PGE₂), interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, and inducible nitric oxide synthase (iNOS) production and nuclear factor-kappa B (NF-κB) activation were down-regulated by two extracts. SPL extract more strongly enhanced the antioxidant and anti-inflammatory activities than SP extract. Its' activities shown more longer fermentation period and more strong inhibitory effects. Taken together, our results suggested that fermented product with medicinal plant has synergic effect and SPL can be a potential candidate for treatment of inflammatory bowel diseases.

• Smart Structures and Systems
• /
• v.29 no.2
• /
• pp.337-350
• /
• 2022

This paper focuses on predicting the post-heating mechanical properties of cementitious composites reinforced with multi-scale additives using the Artificial Neural Network (ANN) approach. A total of four different feed-forward ANN models are developed using 261 data sets collected from 18 published sources. The models are optimized using 12 input parameters selected based on a comprehensive literature review to predict the residual compressive strength, the residual flexural strengths, elastic modulus, and fracture energy of heat-damaged cementitious specimens. Furthermore, the ANN is employed to predict the impact of several variables including; the content of polypropylene (PP) microfibers and carbon nanotubes (CNTs) used in the concrete, mortar, or paste mix design, length of PP fibers, the average diameter of CNTs, and the average length of CNTs. The influence of the studied parameters is investigated at different heating levels ranged from 25℃ to 800℃. The results demonstrate that the developed ANN models have a strong potential for predicting the mechanical properties of the heated cementitious composites based on the mixing ingredients in addition to the heating conditions.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.11a
• /
• pp.133-134
• /
• 2021

Limestone-calcined clay-Cement (LC3) concrete provides a solution for sustainability, durability, and profitability of concrete industry. This study shows experimental studies of the macro properties (residual compressive strength), the meso properties (mesoscopic images), and micro properties (thermogravimetric (TG) analysis, X-ray powder diffraction (XRD), FTIR spectra, Raman spectra, Mercury intrusion porosimetry, and SEM) of LC3 paste with various mixtures and at high elevated temperatures (20 ℃, 300 ℃, 550 ℃ and 900 ℃). We find (1) Regarding to macro properties, LC3 cementitious materials are at a disadvantage in compressive strength when the temperature is higher than 300 ℃. (2) Regarding to meso properties, when the temperature reached 550 ℃, all samples generated more meso cracks. (3) Regarding to micro properties, first, as the substitution amount increases, its CH content decreases significantly; second, at 900 ℃, for samples with calcined clay, a large amount of gehlenite crystalline phase was found; third, at elevated temperatures (20 ℃, 300 ℃, 550 ℃ and 900 ℃), there is a linear relationship between the residual compressive strength and the cumulative pore volume; fourth, at 900 ℃, a large amount of dicalcium silicate was generated, and damage cracks were more pronounced. The experimental results of this study are valuable of material design of fire resistance of LC3 concrete.

• Food Science of Animal Resources
• /
• v.44 no.5
• /
• pp.1156-1166
• /
• 2024

Texture is a major challenge in addressing the need to find sustainable meat alternatives, as consumers desire alternative meat to have a sensory profile like meat. In this study, the fabrication of imitated muscle fiber (IMF) is performed by introducing different kinds of protein sources, with an effective bottom-up technique- wet spinning. Herein, the protein sources (pea protein isolate, wheat protein, and myofibrillar paste) were combined with sodium alginate to stimulate the bonding with the coagulation solution for fabrication. It has been found that the fabrication of IMF is possible using all the protein sources, however, due to the difference in protein structure, a significant difference was observed in quality characteristics compared to conventional meat. Additionally, combination of wheat protein and pea protein isolate has given similar values as conventional meat in terms of some of the texture profiles and Warner-Bratzler shear force. In general, the optimization of protein sources for wet spinning can provides a novel way for the production of edible fiber of alternative meat.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.spc3
• /
• pp.194-198
• /
• 2012

Crystalline silicon solar cell remains the major player in the photovoltaic marketplace with 80% of the market, despite the development of various thin film technologies. Silicon's excellent efficiency, stability, material abundance and low toxicity have helped to maintain its position of dominance. However, the cost of silicon materials remains a major barrier to reducing the cost of silicon photovoltaics. Using the crystalline silicon wafer with thinner thickness is the promising way for cost and material reduction in the solar cell production. However, the thinner the silicon wafer is, the worse bow phenomenon is induced. The bow phenomenon is observed when two or more layers of materials with different temperature expansion coefficiencies are in contact, in this case silicon and aluminum. In this paper, the solar cells were fabricated with different thicknesses of Al layer in order to reduce the bow phenomenon. With less amount of paste applications, we observed that the bow could be reduced by up to 40% of the largest value with 120 micron thickness of the wafer even though the conversion efficiency decrease by 0.5% occurred. Since the bowed wafers lead to unacceptable yield losses during the module construction, the reduction of bow is indispensable on thin crystalline silicon solar cell. In this work, we have studied on the counterbalance between the bow and conversion efficiency and also suggest the formation of enough back surface field (BSF) with thinner Al layer application.