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91.
Joo-Hyoung Park Sang Jun Park Hee Ah Ahn In-Sik Nam Gwon Koo Yeo Jeong Ki Kil Young Kee Youn 《Microporous and mesoporous materials》2009,117(1-2):178-184
Libraries consisting of more than 100 zeolite samples were prepared and examined for developing a promising HC trap catalyst. Parallel adsorptions of toluene onto the catalyst samples were conducted over a 10 × 10 array reactor under dry and wet conditions with or without a heating process three knowledge-based conditions for developing an automotive catalyst during the cold-start period. FAU and BEA type zeolites revealed a high performance of toluene adsorption under the dry condition. However, FAU type zeolite significantly decreased the amount of toluene adsorbed in the presence of water in the feed gas stream, mainly due to the hydrophobicity of the catalyst surface. Over Beta type zeolites, the toluene adsorbed was found to be considerably preserved, even after forced desorption temperature-ramping to the warm-up condition of an automotive engine. Li, K, or Ag ion-exchanged Beta zeolites seem to be particularly promising as an HC trap catalyst. 相似文献
92.
Kai Wang Xiao-Dong Du Kuk-Tae Youn Yasunori Hayashi Chan Gyu Lee Bon Heun Koo 《Metals and Materials International》2008,14(6):689-693
The impact-wear properties of low carbon high manganese alloy steel were tested under three different impact energies (0.7
J, 1.2 J and 1.7 J) using a modified MLD-10 wear tester. SEM inspection of the wear surface and subsurface optical metallographic
analysis reveal the impact wear mechanism. Under corrosive conditions we observe a shift from single micro-cutting to impact-flaking,
after the appearance of vertical section micro-cracks, while at higher impact energies fatigue corrosion and abrasion are
observed. 相似文献
93.
Min Jung Kang Youn Hee Kim Gun Pyo Park Mi Sun Han Woo Nyon Kim Sang Do Park 《Journal of Materials Science》2010,45(19):5412-5419
The effects of liquid-type nucleating silane additives on the cell structure, mechanical strength, and thermal insulating
properties of the polyisocyanurate (PIR) foams have been studied. The PIR foams synthesized with hexamethyldisilazane (HMDS)
as a silane additive showed the smaller average cell size and lower thermal conductivity than those of the PIR foams prepared
with the hexamethyldisiloxane, dimethoxydimethylsilane, and hexadecyltrimethoxysilane. When HMDS was added, average cell size
of the PIR foam was becoming smaller due to lower surface tension of the polyol solution, thereby the nucleation rate and
number of bubbles produced were increased and then the cell size becomes smaller. The additives likely act as nucleating agents
during the formation of PIR foams. The smaller cell size appears to be one of the major reasons for the improvement of thermal
insulation properties and mechanical properties of the PIR foams. From the results of cell size, thermal conductivity, and
mechanical strength of the PIR foams, it is suggested that the HMDS may be the efficient liquid-type additive for the reduction
of cell size and improvement of the thermal insulation property of the PIR foams. 相似文献
94.
Sangjin Jeong Chan‐Hyun Youn Minho Kang Kyoung‐Seon Min Hyun Ha Hong Hae Geun Kim 《ETRI Journal》2002,24(2):97-108
Optical Border Gateway Protocol (OBGP) is an extension to BGP for Optical Cross Connects (OXCs) to automatically setup multiple direct optical lightpaths between many different autonomous domains. With OBGP, the routing component of a network may be distributed to the edge of the network while the packet classification and forwarding is done in the core. However, it is necessary to analyze the stable convergence functions of OBGP in case of lightpath failures. In this paper, we first describe the architecture of the OBGP model and analyze the potential problems of OBGP, e.g., virtual BGP router convergence behavior in the presence of lightpath failure. We then propose an OBGP convergence model derived from an inter‐AS (Autonomous System) relationship. The evaluation results show that the proposed model can be used for a stable OBGP routing policy and OBGP routing convergence under lightpath failures of the optical Internet. 相似文献
95.
J. H. Choi W. H. Lee J. J. Park B. D. Youn 《Structural and Multidisciplinary Optimization》2008,35(6):531-540
Design optimization of layered plate bonding process is conducted by considering uncertainties in a manufacturing process,
to reduce the crack failure arising due to the difference of thermal expansion coefficients of the adherents. Robust optimization
is performed to minimize the mean and variance of the residual stress, which is the major cause of the failure, while constraining
the distortion and the instantaneous maximum stress to the allowable limits. In this optimization, the dimension reduction
(DR) method is employed to quantify the uncertainty of the responses in the bonding process. It is expected that the DR method
benefits the optimization from the perspectives of efficiency, accuracy, and simplicity. Response surface method (RSM) combined
with sequential approximate optimization (SAO) technique is employed as an optimization tool. The obtained robust optimal
solution is verified by the Monte Carlo simulation. 相似文献
96.
M. G. Lee K. Chung C. J. Lee J. H. Park J. Kim T. J. Kang J. R. Youn 《Composites Science and Technology》2001,61(16):2491-2500
In order to optimize the design of unidirectional fiber-reinforced composite (Ilizarov) C-rings, the viscoelastic load relaxation behavior was analyzed under a point load. Initially, the deflection and bending stiffness were calculated from the Castigliano theorem and the Euler–Bernoulli bending theory for the elastic solution. The viscoelastic relaxation and creep behavior were then derived from the elastic solution by using the correspondence theorem. Besides the orthotropic mechanical properties of the composite, the asymmetric mechanical properties due to different tensile and compressive properties were also considered. With the exception of the deviation, which was affected by a relatively large thickness ratio to the radius of the C-ring, the calculated relaxation showed good agreement with the experimental result. 相似文献
97.
This paper proposes an empirical analytical framework for agglomeration economies based on a translog production-inverse input
demand system. Estimation of the system allows us to identify effects on total factor productivity (TFP), partial factor productivity,
factor prices and factor demands. It also provides a decomposition of the aggregate agglomeration elasticity into returns
that arise from the increased efficiency of factor inputs and a “direct” agglomeration effect which exists over and above
any factor augmentation. This enables us to indirectly address the problem of unobserved heterogeneity in factor “quality”.
The paper provides an empirical application of the model using firm level data for UK manufacturing and service industries. 相似文献
98.
Rectangular plates of the size of 1800 × 600 × 12 mm3 and 1200 × 600 × 12 mm3 were selected for injection molding and injection compression molding, respectively, in order to investigate warpage characteristics of the large‐sized polymer plates with orthogonal stiffener. To determine the mold system and to reduce warpage of the specimen, numerical analyses for injection molding and injection compression molding were performed by using a commercial simulation code. Experiments were performed to verify the suggested mold system and warpage of the specimen. Relatively large warpage of the injection molded product was observed and small warpage of the injection compression molded product was generated. Compression force of the injection compression molding was only 6% of the clamp force of the injection molding. Warpage of the product was reduced significantly by using the injection compression molding. The injection compression molding will be used to substitute expensive and disused wood forms with inexpensive and recyclable polymer plates for concrete casting. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
99.
A novel reactive hot melt adhesive was prepared by coating an epoxy resin on maleic anhydride grafted polyethylene (MAPE) powder. This adhesive had markedly improved adhesion power compared with pristine MAPE powder, which is normally used as a hot melt adhesive. The generation of an ester linkage by the reaction between the anhydride group of MAPE and the hydroxyl group of epoxy resin, during the bonding operation at 190°C with the pressure of 22 MPa for 30 min, was confirmed from the FTIR spectra. The bond strength was further improved by a small amount of 1‐methylimidazole, which accelerated the esterification reaction. When the epoxy resin was coated on hydrated MAPE, in which the anhydride group of MAPE was converted into carboxylic acid group by the reaction with water, the esterification reaction was much faster than that of pristine MAPE, and consequently, the bond strength of the adhesive was much higher than that of pristine MAPE coated with epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
100.
Seong Yun Kim Jung Tae Lee Jin Young Kim Jae Ryoun Youn 《Polymer Engineering and Science》2010,50(6):1205-1213
Three‐dimensional flow and structural analyses were carried out for film insert injection molding to investigate warpage of film insert molded (FIM) parts with respect to variation of film and substrate thickness. Asymmetry of temperature distribution in the thickness direction was increased with increasing film thickness but decreased with increasing substrate thickness. Asymmetry of the in‐mold residual stress distribution in the FIM specimen was generated by the nonuniform temperature distribution, and it was increased with increasing film thickness but reduced with increasing substrate thickness. Warpage of the ejected FIM specimen was determined by relaxation of the asymmetric in‐mold residual stress distribution, and it was increased with increasing film thickness but reduced with increasing substrate thickness. Warpage of FIM specimens annealed at 80°C for 30 min showed complex behavior, and the behavior was understood by using factors such as degree of warpage of the ejected part, thermal shrinkage of the inserted film, and retardation of heat transfer. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers 相似文献