• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.167-173
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• 1999

This paper suggests a method to design the deep groove ball bearing for high-load capacity by using a genetic algorithm. The design problem of ball bearings is a typical discrete/continuous optimization problem because the deep groove ball bearing has discrete variables, such as ball size and number of balls. Thus, a genetic algorithm is employed to find the optimum values from a set of discrete design variables. The ranking process is proposed to effectively deal with the constraints in genetic algorithm. Results obtained fer several 63 series deep groove ball bearings demonstrated the effectiveness of the proposed design methodology by showing that the average basic dynamic capacities of optimally designed bearings increase about 9~34% compared with the standard ones.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.38-45
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• 1999

The 2-trowel type concrete floor finishing robot can move in any direction by adjusting the posture or trowels without any wheels. Since the quality of the smoothed and polished concrete floor is determined by plastering speed, we need to control the velocity of the robot. However, we cannot use the typical motion control method because it is very difficult to measure the velocity of the robot, in contrast to the mobile robots with wheels. To overcome this difficulty, the following are studied in this paper: we found that the robot dynamics has the disturbance depending on its translational speed, and showed that there exists the saturated velocity of the robot which is set by the posture of the trowels, and obtained the relationship between the saturated velocity and the posture in the translation. The result enables us to control the motion of the robot only by adjusting the posture of trowels without measuring the velocity of the robot. Currently, we built the troweling robot and are experimenting its performance with the proposed motion control method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.641-645
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• 2002

In case of aluminum-cased battery, The ratio of height and base of square is generally above the ten times, square-shaped and problem of non-axis symmetry. It is typical model to set up the analysis method of finite element. The reliable analysis of finite element method is suggested, which is used to investigate the possibility that multi-stage deep drawing and ironing used currently is replaced by backward impact extrusion favorable in the respect of cost production and productivity. The influence of parameter was analyzed and compared, which was considered to analyze the process of large deformation plasticity such as extrusion. Die and billet was made as the same shape of finite element model. The results of experiment show good forming without the rupture and wrinkles with the optimum velocity 100mm/sec obtained by analysis.

• Korean Journal of Veterinary Research
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• v.39 no.2
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• pp.353-358
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• 1999

New emerging post weaning multisystemic wasting syndrome (PMWS) threatening swine industry worldwide and investigation of the etiological agent is underway. The porcine circovirus (PCV) consistently identified from PMWS pigs and research result indicate that there is strong relationship between PCV and PMWS. Fauns with PMWS submitted pigs suffered from various PMWS typical signs and necropsy finding showed lymph node anomalies. The PCV DNA was amplified from inguinal lymph node collected from pigs with PMWS. PCV specific primers were successfully amplified PCV DNAs and were able to differentiate PCV type I and II. We have identified noble PCV virus with genetic variation. The virus showed insertion of the nucleic acid at the 5' of the genome but did not have PCR product with primer set corresponding to PCV type II virus.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.52.1-52.1
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• 2011

We have implemented the Smoothed Particle Hydrodynamics (SPH) into the cosmological N-body simulation code. The pre-initial particle distribution is set to follow the glacial conditions and the initial temperature of hydro particles is calculated based on the adiabatic process in the expanding backgrounds. Typical adiabatic SPH equations are adopted and, additionally, non-adiabatic processes such as heating/cooling and supernova explosion are added. We study the effect of star formation criteria on the global star formation rate and compare it with the observations.

• Korean Journal of Optics and Photonics
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• v.2 no.1
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• pp.1-6
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• 1991

This paper describes the theoretical analysis of a diffraction pattern analyzer for the characterization of microscale object fields and a method for obtaining size and size distribution from the measured diffraction pattern of the object fields. For the experimental verification, a typical optical Fourier transform system was set up and calibrated with 2 5$\mu \textrm m$ and 50$\mu \textrm m$ pinholes. The system responses to distilled water droplets, alcohol, glycerin and silicon oil were imaged with vidicon, and the image was processed to determine the size distribution of each liquid particle field. The energy distribution function which is defined as the total intensity of a circular ring in the diffraction pattern was used to determine the dominant particle size of each liquid particle field.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.61-68
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• 2001

A parallel nonlinear analysis program of prestressed concrete frame is migrated on a PC cluster system and a massively parallel processing system, CRAY T3E system, using MPI. The PC cluster system is configured with Pentium Ⅲ class PCs and fast ethernet. The CRAY T3E system is composed of a set of nodes each containing one Processing Element (PE), a memory subsystem and its distributed memory interconnect network. Parallel computing algorithms are implemented on element-wise processing parts including the calculation of stiffness matrix, element stresses and determination of material states, check of material failure and calculation of unbalanced loads. Parallel performance of the migrated program is evaluated through typical numerical examples.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.199-208
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• 1994

This paper proposes a delay fault test technique for ICs and PCBs with the boundary-scan architectures supporting ANSI/IEEE Std 1149.1-1990. The hybrid delay fault model, which comprises both of gate delay faults and path delay faults, is selected. We developed a procedure for testing delay faults in the circuits with typical boundary scan cells supporting the standard. Analyzing it,we concluded that it is impractical because the test clock must be 2.5 times faster than the system clock with the cell architect-ures following up the state transition of the TAP controller and test instruction set. We modified the boundary-scan cell and developed test instructions and the test procedure. The modified cell and the procedure need test clock two times slower than the system clock and support the ANSI/IEEE standard perfectly. A 4-bit ALU is selected for the circuits under test. and delay tests are simulated by the SILOS simulator. The simulation results ascertain the accurate operation and effectiveeness of the modified mechanism.

• Journal of the Korean Ceramic Society
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• v.26 no.2
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• pp.267-275
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• 1989

YBa2Cu3O7-x oxide superconductors were fabricated by sintering and hotisostatic pressing (HIP), and their microstructures and properties were compared with each other. Thougha part of the second phase was observed along grain boundaries, their structures were consisted of single (123) phase and they had many porosities. But, porosities were remakably reduced by Hiping and the densification was brought about. The structure of (123) compound also showed a number of twins, which are typical of high Tc superconductors. The on-set temperature of YBa2Cu3O7-x compound sintered at 96$0^{\circ}C$ in oxygen and hipped at 88$0^{\circ}C$ was highest, but that shwoed 0 resistance at 87$^{\circ}$K, which is a little lower than the compound sintered at 96$0^{\circ}C$. HIP treatment also increased the critical current density of as-sintered compound. However, its value was low, which may be ascribed to the many pores of starting-sintered compact and partially to the second phase along grain boundaries.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.3
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• pp.28-38
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• 1998

In our paper is reported a new 3D(dimensional) trajectory split approach with greatly improved efficiency for the Monte Carlo simulation of the 3D profiles of implanted ionand point defect concentrations in single-crystal silicon. This approach has been successfully implemented in our TRICSI Monte Carlo code. Combined with the previously developed model for damage accumalation in our TRICSI code, this model allows phasically based dynamic simulation of 3D profiles over an subsequent process simulation such as diffusion modeling and simulation. A typical time saving of over 10 timeshas been achieved for 3D simulation. Our method ensures much better region aground the implanted area. For 1-D simulation, the optimized condition for trajectory split has set to 3,000 pseudoparticles with 2 split branches.