• Journal of Life Science
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• v.15 no.3 s.70
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• pp.332-336
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• 2005

Epoxide hydrolase activities of various microbial cells were analyzed by colorimetric assay based on alkylation of epoxides with 4-(p-nitrobenzyl)pyridine (NBP). The epoxide hydrolase activity was determined by measuring the decrease of color intensity at 560 nm due to the decrease of styrene oxide substrate by epoxide hydrolase-catalyzed hydrolysis reaction. The experimental conditions of NBP colorimetric assay were optimized for the efficient measurement of epoxide hydrolase activities from various microbial cells.

• Journal of Biomedical Engineering Research
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• v.23 no.4
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• pp.287-293
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• 2002

For non-contact nerve stimulations using time varying magnetic field, high amplitude current pulses have to be applied to a magnetic nerve stimulation coil. To increase the magnetic stimulation frequency we have to increase both power supply capacity and cooling capacity of the magnetic nerve stimulator. To alleviate these problems. we propose a new magnetic nerve stimulation coil design methods. Utilizing magnetic mirror effect of a ferro-magnetic plate attached to a magnetic stimulation coil. we have improved efficiency of the stimulation coil. We have analyzed magnetic mirror effect for various kinds of stimulation coils using the finite element method, and we present experimental results obtained with several kinds of stimulation coils.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.317-324
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• 2008

Optimum design for general or complex structures are required to the need of many numbers of structural analyses. However, current computational environment with single processor is not capable of generating a high-level efficiency in structural analysis and design process for complex structures. In this paper, a virtual parallel computing system communicated by an internet of personal computers and workstation is constructed. In addition, a routine executing Pro/E, ANSYS and optimization algorithm automatically are adopted in the distributed process technique of sequential approximate optimization for the purpose of enhancing the flexibility of application to general structures. By employing the distributed processing technique during structural analysis using commercial application, total calculation time could be reduced, which will enhance the applicability of the proposed technique to the general complex structures.

• The Korean Journal of Food And Nutrition
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• v.29 no.2
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• pp.186-199
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• 2016

The purpose of this study was to determine the optimal composite recipe of rice muffins with 3 concentrations of Spergularia marina L. Griseb, sugar and grape seed oil, using central composite design. In addition, the mixing condition of rice muffins was optimized by subjecting it to sensory evaluation and mechanical and physicochemical analysis using response surface methodology (RSM). In regard to its antioxidant effects, Spergularia marina L. Griseb had a total phenol and flavonoid contents and DPPH free radical scavenging activity of 17.03 mg/g, 5.13 mg/g and 17.21%, respectively. The results of mechanical and physicochemical analysis showed significant values for lightness, redness, yellowness, hardness, springiness, chewiness, gumminess, cohesiveness, height, volume, weight, specific volume, loss rate, pH, moisture, sweetness and saltiness (p<0.05), and the results of sensory evaluation showed significant values for color, flavor, taste, softness, appearance and overall quality (p<0.05). As results, optimal sensory ratio was found to be 6.69 g of Spergularia marina L. Griseb, 41.89 g of sugar and 30.48 g of grape seed oil.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.109-112
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• 1995

The three dimensional, steady flows of blood and blood analogue fluids in the abdominal aortic bifurcation are simulated using the finite volume method. The objective of this investigation is to understand the generation and progression of site-specific atherosclerosis from a hydrodynamic point of view. Due to complexity of blood in conducting experimental study, aqueous polymer solutions are used as the substitutional fluids. For comparison purpose of the flow characteristics of blood and substitutional fluids, rheologically different fluids such as water soluble polymers of Carbopol-934 and Separan AP-273 are employed for the numerical simulation. In order to understand the role of hydrodynamics in the formation and development of atherosclerosis lesions flow velocities, pressures and shear stresses along the vessel are calculated for steady flows.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.466-469
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• 2013

Currently, piezoelectric ceramics are being applied in various fields, such as ultrasonic sensors, vibration devices, sound filters, and various energy conversion devices. Flexible piezoelectric ceramics are widely studied in an effort to mitigate the disadvantages of their brittle and inductile properties. Structural damage to piezoelectric fibers is much less than that to thin films when piezoelectric fibers are twisted or bent. Therefore, stretchable devices can be fabricated if piezoelectric fibers are obtained using an elongated substrate. In this study, sintering processes of PZT ($Pb(Zr_{0.53}Ti_{0.47})O_3$) fibers prepared by electrospinning were optimized through the TGA and XRD analyses. The crystal structure and microstructure of the piezoelectric fibers were investigated by XRD, FE-SEM and TEM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.55-55
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• 2008

이차전지의 음극 중 $LiC_6$는 높은 용량을 보이나 완충하는 프로세스 동안에 금속리튬에 가까운 potential을 갖게 되어 조작에 어려움이 있다. 이러한 대용물질로서 $Li_4Ti_5O_{12}$ spinel은 가볍고 높은 에너지 밀도를 가지고 있고 낮은 전압영역이 가능하여 이차전지의 음극 물질로서 유용하다. 그러나 $Li_4Ti_5O_{12}$ 물질 자체가 insulation이며, 고상합성법을 사용하게 되면 좋은 특성을 나타내기가 어렵다. 이번 실험에서는 고상합성을 통하여 $Ba^{2+}$와 $Sr^{2+}$이온을doping한 후 전기화학적 특성이 어떻게 향상되었는가를 연구하였다. Ba와 Sr을 첨가한 $Li_4Ti_5O_{12}$는 첨가하지 않은 물질에 비하여 보다 안정적인 평탄구역을 갖게 되었으며 방전용량이 $40mAhg^{-1}$의 향상을 가져왔다. 또한 Li half cell에서 100cycle 진행하는 동안 보다 안정적인 전극구조를 유지하였다.

• Journal of Digital Contents Society
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• v.19 no.2
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• pp.401-405
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• 2018

We are living in the age of information and the role of information communication is large. Moreover, the mass commucatioin and the concentration of communication facilities could cause a significant impact on the lives of the people in the event of an accident. Therefore, we proposed improvement measures by analyzing the standard manual of risk management for information communication disaster. The disaster management agency should improve the management system, the related law system, the basic planning and response system, and the standard manual for risk management through continuous research into the statute and the standard manual for risk management.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.308-313
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• 2000

Hydrous titanium oxide particles with anatase phase were prepared from 0.05 mol TiCl4 solution using NH4HCO3 as precipitant by the droopping precipitant method. The sequential change of pH is completed by a sudden and steep increase in a pH value of the range of 6~7 to which the concentration of adsorbed OH- and H+ ions on TiO2 surface is equal. Rutile phase started precipitating with anatase phase as an increase of reaction temperature above 6$0^{\circ}C$ in aqueous 0.05mol TiCl4 solution and its specific surface area was found to decrease from 452 $m^2$/g($25^{\circ}C$) to 164$m^2$/g(8$0^{\circ}C$). Specific surface area decreased rapidly when anatase powders precipitated at 4$0^{\circ}C$ were heat-treated at temperature higher 40$0^{\circ}C$. FT-IR result confirmed that it was due to the decrease of OH species within hydrous titanium oxides. The loss of ethanol after illumination of the powder heated at $600^{\circ}C$ and $700^{\circ}C$ for 4 h was 66 and 68.8%, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.176-176
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• 2010

전자기술이 발전함에 따라 전자부품 소자는 소형화, 다기능화, 고집적화, 대용량화 되고 있다. 그에 따른 부품들의 고밀도화는 높은 열을 발생시켜 각종 전자부품을 기판으로부터 단락 시키거나 기능을 상실하게 하는 문제점이 발생된다. 이와 같은 문제점을 해결하기 위해서는 발생된 열을 가능한 빠르게 방열 시켜주는 것이 대단히 중요하고 높은 방열 특성을 가지는 금속 PCB기판의 중요성이 높아지고 있다. 하지만 금속을 PCB에 적용하기 위해서는 금속기판과 회로전극사이에 절연층이 반드시 필요하다. 본 실험에서는 RF-Magnetron Sputtering 방법을 이용하여 AlN(질화알루미늄)을 절연물질로 사용, Aluminum기판위에 후막을 제작하여 열적 전기적 구조적 특성을 분석 하였다. 스퍼터링시 아르곤과 질소 분압비에 따른 특성과 후막의 두께에 따른 열적, 전기적, 구조적 특성을 측정 분석하였고, 후열처리를 통하여 AlN 후막의 특성 측정 결과 $200^{\circ}C$로 후열처리 했을 경우 절연파괴전압이 후열처리 전 0.56kV보다 1.125kV로 높아지고 SEM 이미지 상의 AlN 입자 밀도가 더욱 조밀해지는 것으로 확인 하였다. 결론적으로 AlN를 RF-Magnetron Sputtering 방법으로 증착 금속 PCB의 절연물질로 적용하기 위해서는 적정한 가스분압비와 후열처리가 필요하며 이를 통하여 금속 PCB의 절연층으로 응용 가능성이 높을 것으로 사료된다. 본 연구는 한국 산업기술 진흥원의 사업화 연계 연구개발(R&BD)사업의 연구비 지원에 의한 것입니다.