• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.5
• /
• pp.2075-2080
• /
• 2013

A Coolant core for Range Extender engine has been developed using CFD technique. Coolant by-pass has been added to the improved model to reduce temperature near and between exhaust valve. Due to the increased coolant flow-rate both around the second cylinder block and between exhaust valves, improved model shows no significant stagnant flow compared with base model. Finally, the improved model shows improved heat transfer coefficients near exhaust valves, and 5% reduced pressure-drop through the coolant core. Reduced pressure-drop may increase the fuel efficiency by reducing the load of a coolant pump.

• Journal of the Korean Society of Safety
• /
• v.28 no.5
• /
• pp.54-60
• /
• 2013

In this study, a finite element model based on the SU/PG scheme was developed to solve shallow-water equations and the influences of parameters and internal boundary conditions on depth-averaged flow behavior were investigated. To analyze the effect of roughness coefficient and eddy viscosity on flow characteristics, the developed model was applied to rectangular meandering channel with two bends, and transverse velocities and water depth distributions were examined. As the roughness coefficient adjacent to wall increased, the velocities near the wall decreased, and the reduced velocities were compensated by the expanding mid-channel velocities. In addition, the flow characteristics around a circular cylinder were analyzed by varying the internal boundary conditions as free slip and no slip. The assignment of slip condition changed the velocity distribution on the cylinder surface and reduced the magnitude of the shear stress up to one third.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.6
• /
• pp.954-959
• /
• 2015

In this paper, 110kW high output density, high efficiency Permanent Magnet Synchronous Motor which can be applied on tram’s traction system is introduced, along with its output and loss characteristics. The motor model is 2pole 18slot model and its size has been reduced through the high speed for high output density. Especially, structure and retainer sleeve structure is applied to its structure, which is also appropriate for high speed rotation. This kind of structure has eddy current loss problem on the surface of rotor, which must be reduced for high output density design. This study has designed the most optimized additional design parameter in order to improve the output characteristics and efficiency of previous produced 2pole 18 slot 110kW motor model and how the width of airgap affects from the loss perspective is mainly analyzed. Finally, the analysis on the extent of the efficiency improvement effect compared to the previous model has performed through electromagnetic FEM analysis. The influence of airgap flux density distribution has also been thoroughly examined.

• Smart Structures and Systems
• /
• v.10 no.4_5
• /
• pp.313-329
• /
• 2012

A challenging issue in design and implementation of an effective structural health monitoring (SHM) system is to determine where a number of sensors are properly installed. In this paper, research on the optimal sensor placement (OSP) is carried out on the Canton Tower (formerly named Guangzhou New Television Tower) of 610 m high. To avoid the intensive computationally-demanding problem caused by tens of thousands of degrees of freedom (DOFs) involved in the dynamic analysis, the three dimension finite element (FE) model of the Canton Tower is first simplified to a system with less DOFs. Considering that the sensors can be physically arranged only in the translational DOFs of the structure, but not in the rotational DOFs, a new method of taking the horizontal DOF as the master DOF and rotational DOF as the slave DOF, and reducing the slave DOF by model reduction is proposed. The reduced model is obtained by IIRS method and compared with the models reduced by Guyan, Kuhar, and IRS methods. Finally, the OSP of the Canton Tower is obtained by a kind of dual-structure coding based generalized genetic algorithm (GGA).

• KIEAE Journal
• /
• v.13 no.6
• /
• pp.83-91
• /
• 2013

Cool roofs are currently being emerged as one of important mechanism to save energy in relation to the building. It is specifically proposed that the changing trends of rooftop surface temperature in the flat roof building model could be used effectively as an indicator to reduced cooling load reduced by cool roof since it can present stable temperature record, that is not influenced according to the nearby physical as well as human variables. The temperature of cool roof in summer was lower around $20^{\circ}C$, compared to the general roofs. Such a seasonal or daily comparative study for rooftop temperature in the building model will highlight that the cool roof efficiency could be calculated in much area-wide context according to rooftop color distribution in urban residential area. It is anticipated that this research output could be used as a valuable reference in identifying energy saving by cool roof since an objective monitoring has been proposed based on the rooftop temperature in the building model, fully quantitative performance of thermal infrared image.

• BMB Reports
• /
• v.47 no.4
• /
• pp.215-220
• /
• 2014

Molecular-targeted therapy has gained attention because of its high efficacy and weak side effects. Previously, we confirmed that transmembrane 4 superfamily member 5 protein (TM4SF5) can serve as a molecular target to prevent or treat hepatocellular carcinoma (HCC). We recently extended the application of the peptide vaccine, composed of CpG-DNA, liposome complex, and TM4SF5 peptide, to prevent colon cancer in a mouse model. Here, we first implanted mice with mouse colon cancer cells and then checked therapeutic effects of the vaccine against tumor growth. Immunization with the peptide vaccine resulted in robust production of TM4SF5-specific antibodies, alleviated tumor growth, and reduced survival rate of the tumor-bearing mice. We also found that serum levels of VEGF were markedly reduced in the mice immunized with the peptide vaccine. Therefore, we suggest that the TM4SF5-specific peptide vaccine has a therapeutic effect against colon cancer in a mouse model.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1111-1117
• /
• 2003

NURBS (Non Uniform Rational B-Spline) is widely used in CAD system and NC data for high speed machining. Conventional CAM system changes NURBS surface to tessellated meshes or Z-map model, and produces linear tool path. The linear tool path is not good for precise machining and high speed machining. In this paper, an algorithm to change linear tool path to NURBS one was studied, and the machining result of NURBS tool path was compared with that of linear tool path. The N-post, post-processing and virtual machining software was developed. The N-Post post-processes linear tool path to NURBS tool path and quickly shades machined product on OpenGL view and compares a machined product with original CAD surface. A virtual machined model of original tool path and post-processed tool path was compared to original CAD model. The machining error of post-processed NURBS tool path was reduced to 43%. The original tool path and NURBS tool path was used to machine general model using same machine tool and machining condition. The machining time of post-processed NURBS tool path was reduced up to 38%.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.2
• /
• pp.76-85
• /
• 1993

Based on the cutting force model, three-dimensional optimal design model was developed and optimal designed tool which is minimized cutting force is developed by computer simulation technique. In this model the objective function which is minimized resultant cutting force was used and the variables are radial rake angle, axial rake angle, lead angle of the tool. The cutting forces using conventional and optimal tools by simulation, are compared and analyzed in time and frequency domains. In time domain the cutting force of optimal tool in feed direction was more reduced and less fluctuated than that of conventional tool. Cutting forces of optimal tool in X-and Z-directions are shown a little increased than those of conventional tool. In frequency domain amplitude of insert frequency components of optimal tool in feed direction was more reduced than that of convent- ional tool. The amplitudes of insert frequency components of optimal tool in X-and Z-direction are a little increased than those of conventional tool. As the reduction of amplitude and fluctuations of the cutting force, Optimal tool is considered that tool life and surface roughness would be improved, and stable cutting would be expected.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.166-167
• /
• 2016

Unlike the past, supported by the development of digital technologies, free-form buildings are frequently designed with creative thoughts of architectural designers. However, there are some difficulties preventing successfully completion of projects, like reduced productivity and increased construction duration and cost upon the process of producing and installing concrete panels for free-form structures. In particular, there are active studies on the CNC machine for production of free-form concrete panels. Yet, it is difficult to effectively and easily come up with information on production and installation of free-form, curve-surfaced panels which are difficult to be mathematically defined. This requires a lot of manpower and time to implement the curved surfaces of free-form buildings as intended by architects. Accordingly, it needs a model that can effectively create production-installation data of free-form concrete panels for successful free-form building projects. Thus, the purpose of the study is to suggest data estimation model of production-installation using mathematical algorithm in free-form concrete panels. The study results will realize effective production and installation of free-form concrete members, allowing improved productivity of projects, reduced cost and shortened construction duration.

• Wind and Structures
• /
• v.5 no.1
• /
• pp.61-80
• /
• 2002

Wind tunnel aeroelastic model tests of the Commonwealth Advisory Aeronautical Research Council (CAARC) standard tall building were conducted using a three-degree-of-freedom base hinged aeroelastic(BHA) model. Experimental investigation into the effects of coupled translational-torsional motion, cross-wind/torsional frequency ratio and eccentricity between centre of mass and centre of stiffness on the wind-induced response characteristics and wind excitation mechanisms was carried out. The wind tunnel test results highlight the significant effects of coupled translational-torsional motion, and eccentricity between centre of mass and centre of stiffness, on both the normalised along-wind and cross-wind acceleration responses for reduced wind velocities ranging from 4 to 20. Coupled translational-torsional motion and eccentricity between centre of mass and centre of stiffness also have significant impacts on the amplitude-dependent effect caused by the vortex resonant process, and the transfer of vibrational energy between the along-wind and cross-wind directions. These resulted in either an increase or decrease of each response component, in particular at reduced wind velocities close to a critical value of 10. In addition, the contribution of vibrational energy from the torsional motion to the cross-wind response of the building model can be greatly amplified by the effect of resonance between the vortex shedding frequency and the torsional natural frequency of the building model.