• Journal of Communications and Networks
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• v.7 no.2
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• pp.222-230
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• 2005

This article presents a field evaluation of an IP-based architecture for heterogeneous environments that has been developed under the aegis of the Moby Dick project, covering UMTS-like (universal mobile telecommunications system) TD-CDMA (time division-code division multiple access) wireless access technology, wireless and wired LANs. The architecture treats all transmission capabilities as basic physical and data-link layers, and replaces all higher-level tasks by IP-based strategies. The Moby Dick architecture incorporates mobile IPv6, fast handovers, AAA-control (authentication, authorisation, accounting), charging and quality of service (QoS) in an integrated framework. The architecture further allows for optimised control on the radio link layer resources. It has been implemented and tested by expert users, and evaluated by real users on field trials with multiple services available.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1019-1021
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• 1999

In this paper, we describe the design and appliance of the preventive diagnostic expert system of gas in oil for power transformer. This expert system is developed to use expert system development tool; Element Expert (NEURON DATA Inc.) Analysis is developed by four diagnose methods. In first, the standard of KEPCO is applied. It classifies the state of transformer by four level: Normal, warning, abnormal and danger. And the others are gas pattern methods, IEC code method, and Dornen & Roger Ratio method and applied later. These latter methods analyse the cause of result. Inference engine was designed with Element Expert. In last, we operate the system with sample data and we can obtain the correctly inferred result for the state of transformer.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.101-107
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• 2005

In this paper, optimized operating parameters were found using multi-dimensional engine simulation software (KIVA-3V) and micro-genetic algorithm for heavy duty diesel engine. The engine operating condition considered was at 1,737 rev/min and 57 % load. Engine simulation model was validated using an engine equipped with a high pressure electronic unit injector (HEUI) system. Three important parameters were used for the optimization - boost pressure, EGR rate and start of injection timing. Numerical optimization identified HCCI-like combustion characteristics showing significant improvements for the soot and $NO_X$ emissions. The optimized soot and $NO_X$ emissions were reduced to 0.005 g/kW-hr and 1.33 g/kW-hr, respectively. Moreover, the optimum results met EPA 2007 mandates at the operating point considered.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.146.2-146.2
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• 2011

In this study, we have derived the abundances of several elements ? Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni - for the six F G K type stars in IC 2391 and the seven stars in NGC 6475. The spectra of those stars are taken from UVES POP archive data, of which resolution is 80,000. To derive the abundances of those elements, TAME (Tools for Automatic Measurement of Equivalent-widths), Kurucz stellar atmospheric model, and MOOG code are used. The stellar parameters (effective temperature, log g, metallicity, microturbulent velocity) are determined from the iron lines. The results provide the abundance differences of chemical elements between two open clusters, IC 2391 (a member of Gould Belt) and NGC 6475 (non-member of it), which would lead to better understanding about Gould Belt.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.69-71
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• 2001

FRP has been used very much as high strength core materials for insulators because of its high strength and good insulation properties. In this study cantilever, tension and torsion stress were simulation along to the unidirection glass fiber. In addition, FRP was made by pultrusion method. This paper proposed the procedure of the finite element model updating and pretest using the commerical finite element code MSC.Nastran. To ehance the efficiency of experimental modal analysis. we proposed the process which is the selection of the locations and the number of measurement points for pre-test.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.206-211
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• 2003

This paper reports the numerical results for blood flow of the sac squeezed by moving actuator in the TPLS(Twin Pulse Life Support System). Blood flow in the sac is assumed to be 3-dimensional unsteady newtonian fluid. where the blood flow interacts with the sac, which is activated by the moving actuator. The flow field is simulated numerically by using the FEM code, ADINA. It is well known that hemolysis is closely related to shear stress acted on blood flow. According to this fact, we simulate four models with different speed for moving actuator and examine the distribution of shear stress for each model. Numerical results show that maximum shear stress is strongly dependent on the actuator speed.

• Structural Engineering and Mechanics
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• v.14 no.2
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• pp.237-243
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• 2002

It is well known that torsionally unbalanced buildings are more vulnerable to earthquake hazards than are the regular structural systems. In this paper, a parametric investigation is presented, in order to observe the amplification in the internal forces, when increased eccentricities are used instead of the ones corresponding to the 5% accidental eccentricity. A series of five, ten-story framed and walled structures, with rather high torsional irregularity coefficients, are selected and a numerical test procedure is applied. Numerical results show that the maximum amplification in the internal forces at the most critical beams and columns at the flexible sides of the structures is about 10%. It is concluded that, more serious measures in the codes are needed in the case of this rather dangerous type of irregularity.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1715-1719
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• 2004

An in-house supersonic ejector was designed to ensure low pressure and high speed scavenging of resonating cavity of chemical lasers. For given primary flow condition, 100g/s secondary mass flow rate was observed at the design pressure. Performance validation of a supersonic ejector system along with an investigation of effects of supersonic diffuser was conducted. Placement of diffuser at the secondary inlet further reduced diffuser upstream pressure to 1/4-1/5 relieving the local to the primary supply unit. In order to increase the secondary flow, we put two ejectors capable of removing 50g/s each of secondary flows together to deal with higher mass flow. Test of the parallel unit demonstrated the secondary flow rate was proportional to the numbers of individual units that were brought together. Additionally, flow calculations with a commercial code were carried out in every case of experiment and compared with results.

• Journal of the Semiconductor & Display Technology
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• v.14 no.4
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• pp.30-37
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• 2015

This research aims to develop Look Ahead position interpolation algorithm for small size CNC machine controlled by PC based controller. Look Ahead scheme can process a bundle of CNC's linear interpolation commands simultaneously, which reduces acceleration and deceleration time within single linear interpolation command. The algorithm is derived as simple analytical form which can be adapted to PC based CNC system by C language programming. The performance of the algorithm was verified by tail stock machining G codes experimentally. The average traverse speed of the CNC machine was increased by 27.5% and the total traverse time also reduced by 27.2% with the Look Ahead scheme.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1313-1315
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• 1996

This paper presents a new method to obtain more stable and precise A/D conversion for remote sensing use. Hardware is designed to compensate offset voltage and drift & temperature characteristics, as well as to perform dual slop A/D converter by using single chip microprocessor. Serial communication program which is based on ASCII code commands is also developed to add initial setup & calibration functions as well as to perform A/D data communication. Proposed method will give a good applications to the industrial field where a high precision remote sensing is required.