• Korean Journal of Computational Design and Engineering
• /
• v.4 no.2
• /
• pp.100-109
• /
• 1999

The bearing design includes the steps of selection bering type, selection bearing subtype, and determining the peripheral equipments. In this paper decision making methodologies are compared to propose a stepwise decision methodology to the bearing selection problem. An artificial neural network trained with design cases is used for selecting a bearing type in the first step. Then the subtype of the bearing is selected using the weighting method, high is a kind of multi-criteria decision making method. Finally, the types of peripheral equipments such as lubrication devices, seals and bearing housings are determined using a rule-based expert system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.10a
• /
• pp.15-17
• /
• 2022

In order to minimize surplus parts in ball bearing selective assembly systems, it is necessary to optimize the selection probability by grasping the dimensional distribution of each part. But the use of a complex system causes delays in the production process. In this paper, we propose cluster priority selection algorithm that can quickly and simply determine the selection priority in ball bearing selective assembly system. In addition, we assume the simulated situation with the data collected in the actual ball bearing selective assembly process, and evaluate the incidence of surplus part and runtime by simulating the cluster priority selection algorithm and the exiting algorithm. As a result of the simulation, the cluster priority selection algorithm generated 83.8% less surplus parts, and 39.7% less runtime than the existing algorithm.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2001.01a
• /
• pp.219-223
• /
• 2001

Within a mechanical system such as an automotive the number of standard machine parts is increasing, so that the parts selection becomes more important than ever before. Selection of appropriate bearings in the preliminary design phase of a machine is also important. In this paper, three decision-making approaches are compared to find out a model that is appropriate to bearing selection problem. An artificial neural network, which is trained with real design cases, is used to select a bearing mechanism at the first step. Then, the subtype of the bearing is selected by the weighting factor method. Finally, types of peripherals such as lubrication methods are determined by a rule-based expert system.

• Toxicological Research
• /
• v.33 no.4
• /
• pp.315-323
• /
• 2017

Preconceptual sex selection is still a highly debatable process whereby X- and Y-chromosome-bearing spermatozoa are isolated prior to fertilization of the oocyte. Although various separation techniques are available, none can guarantee 100% accuracy. The aim of this study was to separate X- and Y-chromosome-bearing spermatozoa using methods based on the viability difference between the X- and Y-chromosome-bearing spermatozoa. A total of 18 experimental semen samples were used, written consent was obtained from all donors and results were analysed in a blinded fashion. Spermatozoa were exposed to different pH values (5.5, 6.5, 7.5, 8.5, and 9.5), increased temperatures ($37^{\circ}C$, $41^{\circ}C$, and $45^{\circ}C$) and ROS level ($50{\mu}M$, $750{\mu}M$, and $1,000{\mu}M$). The live and dead cell separation was done through a modified swim-up technique. Changes in the sex-chromosome ratio of samples were established by double-label fluorescent in situ hybridization (FISH) before and after processing. The results indicated successful enrichment of X-chromosome-bearing spermatozoa upon incubation in acidic media, increased temperatures, and elevated $H_2O_2$. This study demonstrated the potential role for exploring the physiological differences between X-and Y-chromosome-bearing spermatozoa in the development of preconceptual gender selection.

• Tribology and Lubricants
• /
• v.16 no.1
• /
• pp.39-45
• /
• 2000

In this paper, the effects of shaft and bearing flexibilities are investigated for the accurate modeling of a shaft-bearing system supported by ball bearings. Generally, rolling bearings are modeled by simple rigid pin-joint in the mechanical design. However, they can no longer be modeled by ideal boundary conditions in the advanced applications because the rigid pin-joint model cannot satisfy the current trends of mechanical design decreasing mass and reducing volume. Consequently the flexible support model of ball bearing is investigated using the static analysis module developed by A .B. Jones and T. A. Harris. A simple two-bearing system, supported by two deep groove ball bearings and radially loaded on the shaft midway between the bearings, is utilized to validate the coupled model of shaft-bearing system. Numerical computations using the model indicate that the shaft span length, locating/floating bearing arrangements and applied bearing size are significant factors in determining the mechanical behaviors. The flexible support model of ball bearing can be escaped to over-estimate in the bearing fatigue life. The proposed simple design formulation obtained by numerical simulations can approximately predict a rate of bearing life reduction as a function of shaft span length/shaft diameter (L/d).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.1
• /
• pp.162-167
• /
• 2002

An automotive wheel bearing is one of the most important components to guarantee the service life of a passenger car. The endurance life of a bearing is affected by many parameters such as material properties, heat treatment, lubrication conditions, temperature, loading conditions, bearing geometry, internal clearance and so on. In this paper, we analyze the relation between loads and deformations of wheel bearing units. On the basis of it, we calculate the endurance life of wheel bearing units and suggest a method to determine the initial contact angle to achieve a maximum endurance life with considering stress concentration.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2007.11a
• /
• pp.457-458
• /
• 2007

• Journal of Life Science
• /
• v.30 no.3
• /
• pp.239-249
• /
• 2020

Persimmon flowers are fruit-bearing female, pollen-bearing male, or hermaphrodite, containing both a pistil and a stamen. Using prominent PCNA persimmons as male parents is very important for breeding programs, as the selection procedure for new cultivars bearing male flowers requires a long time and a large field in a traditional crossbreeding method. To improve breeding efficiency through early selection of male flower-bearing plants at the seedling stage, analysis was performed on 88 major cultivars whose gender expressions are known, using two male flower selection markers recommended by Akagi et al. The OGI locus marker and DISx-AF4S marker results showed that 83 and 72 cultivars, respectively, matched in terms of gender expression and marker analysis. For the OGI locus marker, 890 plants were selected from 2,509 seedlings obtained from crossbreeding with the mother plant "Migamjosang," which was the breeding cultivar. Comparing the gender expression of the flowers and the marker with 1,186 crossbred seedlings, excluding the unfertilized and dead plants, inconsistencies were found in 401 plants (33.8%). For the DISx-AF4S marker, 636 plants were selected from 889 seedlings obtained from 12 cross-combinations. The results of the sex expression and marker analysis were compared to 379 plants, excluding the unfertilized and dead plants, and inconsistencies were found in 247 plants (65.2%). These results indicate that the examined DISx-AF4S and OGI locus markers would not be suitable for utilization in the breeding field.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.3
• /
• pp.337-342
• /
• 1998

In this paper the lubrication performances of line pivoted pad thrust bearing and point pivoted pad thrust bearing are studied by a numerical analysis. The running characteristic parameters such as nondimensional load carrying capacity nondimensional friciton power loss nondimensional flow rate and film thickness ratios are calculated for various circumferential pivot positions. The results provide a usdful data for the selection of pivot position in a pivoted and thrust bearing.

• Proceedings of the KSR Conference
• /
• 1999.05a
• /
• pp.367-374
• /
• 1999

The selection of geogrid types for the use of reinforced rail roadbed is important in the design of railways. Also, the problem of the construction damage on the geogrid during construction is raised by the field engineers. Therefore, laboratory model tests were peformed to investigate the efficiency of the bearing capacity and construction damage. As a result, it was found that the bearing capacity of the rigid geogrid reinforced railroad ballast shows 1.54 times higher than that of the flexible geogrid reinforced case. In addition, there were no noticeable damage during construction.