• Journal of Microbiology and Biotechnology
• /
• v.24 no.12
• /
• pp.1636-1643
• /
• 2014

3-Hydroxybutyryl-CoA dehydrogenase is an enzyme that catalyzes the second step in the biosynthesis of n-butanol from acetyl-CoA, in which acetoacetyl-CoA is reduced to 3-hydroxybutyryl-CoA. To understand the molecular mechanisms of n-butanol biosynthesis, we determined the crystal structure of 3-hydroxybutyryl-CoA dehydrogenase from Clostridium butyricum (CbHBD). The monomer structure of CbHBD exhibits a two-domain topology, with N- and C-terminal domains, and the dimerization of the enzyme was mostly constituted at the C-terminal domain. The mode of cofactor binding to CbHBD was elucidated by determining the crystal structure of the enzyme in complex with $NAD^+$. We also determined the enzyme's structure in complex with its acetoacetyl-CoA substrate, revealing that the adenosine diphosphate moiety was not highly stabilized compared with the remainder of the acetoacetyl-CoA molecule. Using this structural information, we performed a series of site-directed mutagenesis experiments on the enzyme, such as changing residues located near the substrate-binding site, and finally developed a highly efficient CbHBD K50A/K54A/L232Y triple mutant enzyme that exhibited approximately 5-fold higher enzyme activity than did the wild type. The increased enzyme activity of the mutant was confirmed by enzyme kinetic measurements. The highly efficient mutant enzyme should be useful for increasing the production rate of n-butanol.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.40 no.11
• /
• pp.957-962
• /
• 2012

Fluid/structure interaction (FSI) analysis is necessary to predict the response of a system in which aerodynamic pressure causes deformation of the structure, and vice versa. In dealing with a nonlinear behavior of the structure, however, a simple iterative algorithm of aerodynamic analysis with structural analysis yields no accurate results since aerodynamic pressure need to be changed in accordance with the deformation of structures. In this study, we explore an efficient and accurate method for integrating FSI analysis into structural nonlinear systems. During the course of nonlinear structural analysis, loading conditions are periodically updated by aerodynamic analysis. The accuracy and efficiency of the method is demonstrated with a high-aspect-ratio flexible wing of Global Hawk.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.43 no.3 s.309
• /
• pp.92-99
• /
• 2006

In this paper, a low-power deblocking filter structure for H.264 video coding algorithm is proposed. By sharing addition hardware for common filter coefficients, we have designed an efficient deblocking filter structure. Proposed deblocking filter utilizes MUX and DEMUX circuits for input data sharing and shows 44.2% reduction for add operation. In the HDL coding simulation and FPGA implementation, we achieved 19.5% and 19.4% gate count reduction, respectively, comparison with the conventional deblocking filter structure. Due to its efficient processing scheme, the proposed structure can be widely used in H.264 encoding and decoding SoC.

• Journal of Korea Multimedia Society
• /
• v.9 no.9
• /
• pp.1231-1246
• /
• 2006

HTML is a format for rendering Web documents visually and uses tables to present a relational information. Since HTML has limits in terms of information processing and management by a computer, it is important to transform HTML tables into XML documents, which is able to represent logical structure information. As a prerequisite for extracting information from the Web, this paper presents an efficient method for extracting logical structures from HTML tables and transforming them into XML documents. The proposed method consists of two phases: Area segmentation and structure analysis. The area segmentation step removes noisy areas and extracts attribute and value areas through visual and semantic coherency checkup. The hierarchical structure between attribute and value areas are analyzed and transformed into XML representations using a proposed table model. Experimental results with 1,180 HTML tables show that the proposed method performs better than the conventional method, resulting in an average precision of 86.7%.

• KIPS Transactions on Computer and Communication Systems
• /
• v.2 no.7
• /
• pp.293-302
• /
• 2013

Home network providers have many worries about providing home network services with an expandable, reliable, flexible and low-cost structure according to the expanding market environment. The existing client-server system has various problems such as complexity and high costs in providing home network services. In this paper we propose the P2P-SIP structure. P2P communication terminal supporting access of distributed resources provides functions which the existing SIP-based network devices have. Because diverse terminals in a home network access through networks, also, partitioning network domains with home gateways to manage, and applying the network-based PMIPv6(Proxy Mobile IPv6) technology considering mobility of terminals would help to have a more efficient home network structure. Especially, the proposed P2P-SIP structure proves itself as a very efficient structure to have an outstanding expandability among different home networks in a region, and to reduce maintenance costs.

• Structural Engineering and Mechanics
• /
• v.40 no.1
• /
• pp.85-103
• /
• 2011

Integration of finite element analysis (FEA) software into various software platforms is commonly used in coupling systems such as systems involving structural control, fluid-structure, wind-structure, soil-structure interactions and substructure method in which FEA is used for simulating the structural responses. Integrating an FEA program into various other software platforms in an efficient and simple way is crucial for the development and performance of the entire coupling system. The lack of simplicity of the existing integration methods makes this integration difficult and therefore entails the motivation of this study. In this paper, a novel practical technique, namely CS technique, is presented for integrating a general FEA software framework OpenSees into other software platforms, e.g., Matlab-$Simulink^{(R)}$ and a soil-structure interaction (SSI) system. The advantage of this integration technique is that it is efficient and relatively easy to implement. Instead of OpenSees, a cheap client handling TCL is integrated into the other software. The integration is achieved by extending the concept of internet based client-server concept, taking advantage of the parameterization framework of OpenSees, and using a command-driven scripting language called tool command language (TCL) on which the OpenSees' interface is based. There is no need for any programming inside OpenSees. The presented CS technique proves as an excellent solution for the coupling problems mentioned above (for both linear and nonlinear problems). Application examples are provided to validate the integration method and illustrate the various uses of the method in the civil engineering.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.45 no.3
• /
• pp.103-110
• /
• 2008

In this paper, an efficient butterfly structure for 8K/2K-Point Radix-4 FFT algorithm using CORDIC(coordinate rotation digital computer) is proposed. It is shown that CORDIC can be efficiently used in twiddle factor calculation of the Radix-4 FFT algorithm. The Verilog-HDL coding results for the proposed CORDIC butterfly structure show 36.9% cell area reduction comparison with those of the conventional multiplier butterfly structure. Furthermore, the 8K/2K-point Radix-4 pipeline structure using the proposed butterfly and delay commutators is compared with other conventional structures. Implementation coding results show 11.6% cell area reduction. Due to its efficient processing scheme, the proposed FFT structure can be widely used in large size of FFT like OFDM Modem.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.5
• /
• pp.2646-2659
• /
• 2017

Equipped with the advantages of flexible access control and fine-grained authentication, attribute based signcryption is diffusely designed for security preservation in many scenarios. However, realizing efficient key evolution and reducing the calculation costs are two challenges which should be given full consideration in attribute based cryptosystem. In this paper, we present a key-policy attribute based signcryption scheme (KP-ABSC) with delegated computation and efficient key updating. In our scheme, an access structure is embedded into user's private key, while ciphertexts corresponds a target attribute set. Only the two are matched can a user decrypt and verify the ciphertexts. When the access privileges have to be altered or key exposure happens, the system will evolve into the next time slice to preserve the forward security. What's more, data receivers can delegate most of the de-signcryption task to data server, which can reduce the calculation on client's side. By performance analysis, our scheme is shown to be secure and more efficient, which makes it a promising method for data protection in data outsourcing systems.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.261-264
• /
• 2008

Recently, as necessity for urban recycling has increased, the research on integrated multi-purpose space has been required. Development of the system for integrated multi-purpose space is needed to form the efficient and higher value-added space. In this research, the notion of integrated multi-purpose space is defined and two proposed structural system, which are space truss and mega structure system, are compared. Mega structure system has been found as more proper system and proposed for analysis. As verified by the number of mega beam and shape of mega column, the analysis has been carried out. The results show that mega structure system offers proper performance for integrated multi-purpose space.

• Earthquakes and Structures
• /
• v.13 no.6
• /
• pp.561-572
• /
• 2017

Seismic base isolation has been accepted as one of the most popular design procedures to protect important structures against earthquakes. However, due to lack of information and experimental data the application of base isolation is quite limited to nuclear power plant (NPP) industry. Moreover, the effects of inelastic behavior of soil beneath base-isolated NPP have raised questions to the effectiveness of isolation device. This study applies the wavelet analysis to investigate the effects of soil-structure interaction (SSI) on the seismic response of a base-isolated NPP structure. To evaluate the SSI effects, the NPP structure is modelled as a lumped mass stick model and combined with a soil model using the concept of cone models. The lead rubber bearing (LRB) base isolator is used to adopt the base isolation system. The shear wave velocity of soil is varied to reflect the real rock site conditions of structure. The comparison between seismic performance of isolated structure and non-isolated structure has drawn. The results show that the wavelet analysis proves to be an efficient tool to evaluate the SSI effects on the seismic response of base-isolated structure and the seismic performance of base-isolated NPP is not sensitive to the effects in this case.