• 한국재료학회지
• /
• 제16권5호
• /
• pp.323-328
• /
• 2006

In situ electrical conductivity measurements on $V_2O_5WO_3/TiO_2$ catalysts were carried out at between 100 and $300^{\circ}C$ under pure oxygen, NO and $NH_3$ to investigate the reaction mechanism for ammonia SCR (selective catalytic reduction) de NOX. The electrical conductivity of catalysts changed irregularly with supply of NO. It was, however, found that the electrical conductivity change with ammonia supply was regular and the increase of electrical conductivity was mainly caused by reduction of the labile surface oxygen. The electrical conductivity change of catalysts showed close relationship with the conversion rate of NOx. Variation of conversion rate in atmosphere without gaseous oxygen also showed that labile lattice oxygen is indispensable in the initial stage of the de NOx reaction. These results suggest that liable lattice oxygen acts decisive role in the de NOx mechanism. They also support that de NOx reaction occurs through the Eley?Rideal type mechanism. The amount of labile oxygen can be estimated from the measurement of electrical conductivity change for catalysts with ammonia supply. This suggests that measurement of the change can be used as a measure of the de NOx performance.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.150.2-150.2
• /
• 2011

Unlike non-ionic clathrate hydrates stably formed by van der Waals interaction between a guest molecule and a surrounding host framework, ionic clathrate hydrates are stabilized by ionic interaction between an ionic guest molecule and the host water-framework. Here, we firstly described the stable entrapment of the superoxide ions in ${\gamma}$-irradiated $Me_4NOH+O_2$ hydrate. Owing to peculiar direct guest-guest ionic interaction, the lattice structure of ${\gamma}$-irradiated $Me_4NOH+O_2$ hydrate shows significant change of lattice contraction behavior even at relatively high temperature(120K). Particularly, we note that ionic-induced dimensional change is much greater than thermal-induced change. Such findings are expected to provide useful information for a better understanding of unrevealed nature of clathrate hydrate fields.

• 한국유체기계학회 논문집
• /
• 제14권6호
• /
• pp.45-53
• /
• 2011

Multiphase lattice Boltzmann method (LBM) has been used to simulate the nucleate pool boiling directly. For the phase change model, the thermal model and the Stefan boundary condition were introduced to the isothermal LBM. The phase change model was validated by the bubble growth in a superheated liquid under no gravity. The bubble growth on and departure from a superheated wall has been simulated successfully. The preliminary results showed that the detail process of nucleate pool boiling was in good agreement with the experimental results.

• Steel and Composite Structures
• /
• 제24권2호
• /
• pp.249-264
• /
• 2017

In this paper free linear vibration of lattice composite conical shells will be investigated. Lattice composite conical shell consists of composite helical ribs and thin outer skin. A smeared method is employed to obtain the variable coefficients of stiffness of conical shell. The ribs are modeled as a beam and in addition to the axial loads, endure shear loads and bending moments. Therefore, theoretical formulations are based on first-order shear deformation theory of shell. For verification of the obtained results, comparison is made with those available in open literature. Also, using FEM software the 3D finite element model of composite lattice conical shell is built and analyzed. Comparing results of analytical and numerical analyses show a good agreement between them. Some special cases as variation of geometric parameters of lattice part, effect of the boundary conditions and influence of the circumferential wave numbers on the natural frequencies of the conical shell are studied. It is concluded, when mass and the geometrical ratio of the composite lattice conical shell do not change, increment the semi vertex angle of cone leads to increase the natural frequencies. Moreover for shell thicknesses greater than a specific value, the presence of the lattice structure has not significant effect on the natural frequencies. The obtained results have novelty and can be used for further and future researches.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.411-414
• /
• 2007

The confinement-shear lattice(CSL) model for hardened concretes developed by Cusatis is extended for early age concretes. The uniaxial behaviors available in the literature for 3 to 28 days were simulated by the CSL model to identify the change of the model parameters for various ages. The change with respect to the age was interpolated based on the chemomechanics to develop the extended version of CSL model.

• 대한전자공학회논문지SD
• /
• 제42권11호
• /
• pp.17-22
• /
• 2005

21세기 광통신 분야는 보다 많은 정보를 동시에 전송하기 위해 다양한 다중화 방식들을 요구 받고 있다. 광섬유 Brags격자 소자를 이용한 모든 광 분기/결합 장치는 분기/결합할 수 있는 신호가 광섬유 격자 소자의 Bragg파장에 의해 정해지므로 하나의 광섬유 격자 소자는 고정된 한 채널만을 분기, 결합할 수 있다는 단점을 지니고 있다. 그러나 광섬유 격자에 온도와 스트레인(strain) 같은 외부 물리량을 가하게 되면 광섬유 격자의 주기가 변하게 되어 반사파장이 고정되지 않고 파장을 가변 할 수 있는 장점을 가지게 된다. 이에 본 논문에서는 광섬유 격자 소자에 가해진 온도, 스트레인에 의해 Bragg파장이 변화하는 성질을 이용하여 파장 가변형 Bragg 격자를 제작 및 실험을 통하여 전광필터 특성에 대하여 제시하였다.

• 한국가구학회지
• /
• 제24권4호
• /
• pp.400-407
• /
• 2013

21C modern society is a time when enough design to dominate the world, a unique design is required new in all aspects. In addition, there is a religion to the best of Zen art. In our cultural heritage with a ethnicity unique unparalleled in the world, and a new recognition of traditional culture and identity of its own in our country, lattice door flower temple the beauty of Korea in the way you tell, it was modernized by interpreting a new one to utilize as a design element of a wood lattice door flower temple. In this study, to re-appear in openwork having regard to the symbolism of pattern and shape of the lattice door flower temple molding properties were highlighted, change the part of the motif, repeated the curve geometric has been designed to simplify as. As a result, it is possible to present the possibility of a design element that can design a traditional Korean is reinterpreted Modern thereby simplify the repetitive element of the related art, for a new aesthetic changes unique. Design Development of wood with a Buddhist temple flower lattice modern re-interpretation, it suits while a strong indication Korea imagery and expressed a variety of needs and personality to the design elements that are competitive in the world the cage, and design of wood, various studies competitive on to be applied to each field is required.

• Journal of Mechanical Science and Technology
• /
• 제16권10호
• /
• pp.1327-1335
• /
• 2002

The shock wave process represents an abrupt change in fluid properties, in which finite variations in pressure, temperature, and density occur over the shock thickness which is comparable to the mean free path of the gas molecules involved. This shock wave fluid phenomenon is simulated by using the finite difference lattice Boltzmann method (FDLBM). In this paper, a new model is proposed using the lattice BGK compressible fluid model in FDLBM for the purpose of speeding up the calculation as well as stabilizing the numerical scheme. The numerical results of the proposed model show good agreement with the theoretical predictions.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.468-474
• /
• 2001

The shock process represents an abrupt change in fluid properties, in which finite variations in pressure, temperature, and density occur over a shock thickness which is comparable to the mean tree path of the gas molecules involved. The fluid phenomenon is simulated by using finite difference lattice Boltzmann method (FDLBM). In this research, the new model is proposed using the lattice BGK compressible fluid model in FDLBM for the purpose of shortening in calculation time and stabilizing in simulation operation. The numerical results agree also with the theoretical predictions.

• 한국세라믹학회지
• /
• 제15권2호
• /
• pp.66-71
• /
• 1978

The cobalt blue spinel stains (main composition; CoO:$Al_2O_3$=1 : 1) in CoO-NiO-$Al_2O_$3 and $CoO-Al_2O_3-Cr_2O_3$ system were prepared by the calcination of each component oxides to be adequate for the factory. The color development, the change of the lattice constnat of the spinel and its application to colored glazes were studied. The results were summarized as follows. 1) In CoO-Al_2O_3$ spinel, the excess addition of each component hardly made any variation in lattice constantand alumina-rich spinel specimens caused the brilliant blue color fade. 2) An increase of $Ni^{2+}$ in $CoO-NiO-Al_2O_3$ system, made the lattice constnat of the $CoO-Al_2O_3$ spinel smaller, and an increase of $Cr^{3+}$ in $CoO-Al_2O_3-Cr_2O_3$, larger. 3) Glazed stains under lead glaze were colored nearly same dark blue color fade.