• Proceedings of the KIEE Conference
• /
• 2007.11c
• /
• pp.138-140
• /
• 2007

$TiO_2-V_2O_5$ sol was fabricated using sol-gel method and $TiO_2-V_2O_5$ thin films were fabricated using dip-coating method. $V_2O_5$ sol was added 0.01mo1e, 0.03mo1e, 0.05mo1e into $TiO_2$ sol. Viscosity of sol increased fast from about 1,000 minutes and sol began gelation from about 10,000 minutes. As a results of crystalline properties, $V_2O_5$ peaks were not found despite of $V_2O_5$ addition. Endothermic reaction occurred due to evaporation of solvent and dissociation of OH at $80^{\circ}C$. Exothermic reaction occurred due to combustion and oxidation of solvent at $230^{\circ}C$, occurred to combustion and oxidation of alkyl group at $350^{\circ}C$. Thickness of thin films increased $0.1{\sim}0.25{\mu}m$ every a dipping.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.10 no.1
• /
• pp.64-69
• /
• 2014

Gr. 91 steel is used for the major structural components of Generation-IV reactor systems, such as a very high temperature reactor(VHTR) and sodium-cooled fast reactor(SFR). Since these structures are designed for up to 60 years at elevated temperatures, the prediction of long-term creep life is important for a design application of Gr. 91 steel. In this study, a number of creep rupture data were collected through world-wide literature surveys, and using these data, the long-term creep life was predicted in terms of three methods: the single-C method in Larson-Miller(L-M) parameter, multi-C constant method in the L-M parameter, and a modified method("sinh" equation) in the L-M parameter. The results of the creep-life prediction were compared using the standard deviation of error value, respectively. Modified method proposed by the "sinh" equation revealed better agreement in creep life prediction than the single-C L-M method.

• Journal of the Optical Society of Korea
• /
• v.20 no.6
• /
• pp.653-662
• /
• 2016

An optimized multilayer superlens is designed, using a rigorous and efficient approach based on the method of moments (MoM) in conjunction with a simulated annealing (SA) algorithm. For the MoM solution, fast evaluation of closed-form Green's functions (GFs) in the spatial domain is performed by applying the complex-image (CI) technique, which obviates the time-consuming numerical evaluation of Sommerfeld integrals. The imaging capability of the superlens is examined with the correlation coefficient; results show that using circular polarization for the incident wave can improve this coefficient. To validate the proposed method, finite-element-based simulations are exploited, which reveal the method's accuracy and computational efficiency. Simulation results indicate that the designed structure is capable of producing two-dimensional sub-diffraction-limited images in the visible range, which may make it more versatile for practical applications. Finally, as a considerable finding, it is demonstrated for the proposed design that using circularly polarized illumination provides improved super-resolving performance, compared to linearly polarized illumination.

• KSBB Journal
• /
• v.8 no.4
• /
• pp.341-350
• /
• 1993

As an effort to develop an alternative transportation fuel, the production of methanol from methane gas was studied using the resting cells of an obligatory methanotroph, Methylosinus trichosporium OB3b. The reaction was carried out in high concentration phosphate buffer solutions with the flask-grown cells containing the exclusively cytoplasmic methane monooxygenase (sMMO) activity. The methanol accumulation rate was observed to be 79nmo1/mg·min during the initial 4.5hr. Phosphate-dependent inhibition was found for both sMMO and methanol dehydrogenase (MDH) activities, and the inhibition constants were 185mM and 42mM, respectively. The inhibition mode was noncompetitive. Methanol was found to be very inhibitory to the sMMO activity and the inhibition constant (noncompetitive) was 21mM when propylene was used as substrate. The sMO activity in the resting cells was declined very fast and the rate became very high during the methanol production. These results indicate that the use of M. trichosporium OB3b as a biocatalyst for the methanol production is heavily dependent on the stable maintenance of the whole-cell SMO activity as well as the effective alleviation of product inhibition.

• Journal of Magnetics
• /
• v.17 no.1
• /
• pp.6-8
• /
• 2012

M$\ddot{o}$ssbauer spectra of hexagonal $BaFe_{12}O_{19}$ single crystals were studied at various temperatures (4-300 K). It was found that the spin states in Fe atoms were parallel to the ${\gamma}$-ray's direction into a single crystal along the caxis. The location of the Fe ion in the 2b site is unusual in an oxide structure and has strong anisotropic lattice vibrations. Moreover, at room temperature, the zero absorption lines of the Fe ions at the 2b site were observed due to fast diffusion motion in a double well atomic potential. The two Fe ions of the single crystal mainly enter into the sites in the mirror plane of the trigonalbipyramidal structure.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.2
• /
• pp.257-266
• /
• 1999

In this paper, a spline-type divided-difference interpolation technique is proposed to efficiently evaluate the impedance matrix elements in the MoM analysis of layered medium problems. This method is combined with the fast computational method of the basis-expanded and tested dyadic Green's functions (expressed in the spectral domain integrals) in a recent literature. For the sake of its validity, the proposed method is applied to analyze the characteristics of a microstrip gap discontinuity, a microstrip filter, and an aperture coupled patch antenna. Numerical results obtained by this approach are in good agreement with those of other approaches.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.130-131
• /
• 2009

얼굴 영역 검출은 얼굴 인식, 얼굴 복원 등 산업 및 학술 여러 분야에 걸쳐 사용되는 기술이다. 고속의 얼굴 영역 검출을 위하여 고성능 하드웨어를 사용하거나 고속 알고리즘을 사용하는데, 본 논문에서는 GPU 기반 프로그래밍 기법인 CUDA를 이용하여 고속 얼굴 영역 검출 시스템을 구현하였다. 기존의 얼굴 영역 검출 시스템은 처리 속도의 한계로 인해 고속의 검출이 어려웠을 뿐 아니라 고속으로 동작하도록 하려면 고가의 시스템 부품을 사용하여야 하므로 사용자에게 부담을 안겨주었다. 그러나 nVidia 등 그래픽 칩셋 제조업체들이 속속 내놓고 있는 GPGPU 기술을 이용하여 얼굴 영역 검출 시스템을 구현할 경우 보다 저렴한 가격에 보다 뛰어난 성능을 가질 수 있도록 할 수 있다. 따라서 본 논문에서는 이러한 범용 GPU 사용 기술 중 하나인 nVidia의 CUDA를 이용하여 얼굴 검출 시스템을 구현하였다. 실험 결과 GPU 기반 시스템은 CPU 기반 시스템보다 고속으로 검출이 가능함을 확인하였다. 제안하는 방법은 nVidia 그래픽 카드가 설치된 시스템에서 고속의 감시카메라 서버 등으로 적용이 가능하다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.132-133
• /
• 2009

움직임 검출 시스템은 감시카메라에서 불필요한 녹화를 방지하는 방법으로 널리 사용되고 있다. 그러나 최근 출시되고 있는 고화질 CCTV 카메라에서는 연산의 복잡도 때문에 실시간 처리가 어려운 실정이다. 이를 해결하기 위해 본 논문에서는 CUDA를 이용한 고속 움직임 탐지 시스템을 구현하였다. 기존의 움직임 탐지 시스템은 처리 속도의 한계로 인해 고속의 탐지가 어려웠을 뿐 아니라 고속으로 동작하도록 하려면 고가의 시스템 부품을 사용하여야 하므로 사용자에게 부담을 안겨주었다. 그러나 최근 발전을 거듭하고 있는 고속의 GPU를 이용하여 움직임 탐지 시스템을 구현할 경우 보다 저렴한 가격에 보다 뛰어난 성능을 가질 수 있도록 할 수 있다. 따라서 본 논문에서는 이러한 범용 GPU 사용기술인 nVidia의 CUDA를 이용하여 움직임 탐지 시스템을 구현하였다. 실험 결과 GPU 기반 시스템은 CPU 기반 시스템보다 80배가량 속도의 향상이 있었다. 제안하는 방법은 nVidia 그래픽 카드가 설치된 시스템에서 고속의 감시카메라 서버 등으로 적용이 가능하다.

• Korean Journal of Metals and Materials
• /
• v.47 no.4
• /
• pp.209-216
• /
• 2009

It was evaluated that the microstructural and mechanical properties of Ta-bearing 9Cr-0.5Mo-2W ferritic/martensitic experimental steels. All the experimental steels showed the tempered martensitic microstructures, and $M_{23}C_6$ carbides, whose sizes were ranged from 200 to 300 nm, were easily observed at both boundaries of the prior austenite grain and the martensite lath. In addition, a relatively large Nb-rich MX carbonitrides were intermittently detected at the prior austenite grain boundaries, whereas a lot of Vrich MX carbonitrides, whose mean diameter was less than 50 nm, were observed randomly at both boundaries. Ta was mainly incorporated into the V-rich MX carbonitrides rather than the Nb-rich ones and their content was spanned from 5 to 20 at.%. Ta contents within the MX precipitates also increased as the content of Ta increased. Because the Ta addition into the steels would be attributed to the precipitation strengthening, solid solution strengthening and lath width reduction, it was shown that the mechanical properties, including hardness, tensile strength and creep rate of the 9%Cr-0.5Mo-2W steels were improved by the increase of Ta content. Especially, 9Cr-0.5Mo-2W-0.3V-0.05Nb-0.14Ta steel was revealed to be relatively excellent in the application for the SFR fuel cladding.

• Nuclear Engineering and Technology
• /
• v.30 no.6
• /
• pp.568-580
• /
• 1998

A sodium-concrete reaction facility with a test chamber of 0.226㎥($\Phi$0.6m$\times$H0.8m) was constructed to carry out experiments of sodium-concrete reaction which might take place in sodium metal fast-breeder reactor Utilizing this facility, several experiments were conducted to closely examine the characteristics of sodium-concrete reactions under different conditions : Sodium mass : 100, 250g ; Sodium temperature : 450, 550, $650^{\circ}C$ ; Concrete age = 30, 45, 50, 90days. Our experiments show that the amount of the H2 generated by sodium-concrete reaction has increased up to its flammable range as the amount of spilled sodium and its temperature have increased. The maximum hydrogen concentration was 31mo1% at the concrete age of 30days, sodium temperature : 55$0^{\circ}C$, and sodium mass : 250g. The major components of sodium-concrete reaction products were also determined as Na$_2$SiO$_3$ and NaAlO$_2$.