• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.2014-2015
• /
• 2007

This paper deals with design and analysis of thrust magnetic bearing. Using the solutions obtained from equivalent magnetic circuit, we predict the electromagnetic characteristics such as thrust, time constant and power loss according to design parameters. And then, using non-linear finite element analysis, a detailed design is performed considering saturation in order to meet requirements.

• Wind and Structures
• /
• v.30 no.1
• /
• pp.1-13
• /
• 2020

The loss prediction and assessment during extreme events such as wind hazards is always crucial for the group low-rise residential buildings. This paper analyses the effect of variation in building density on wind-induced loss for low-rise buildings and proposes a loss assessment method consequently. It is based on the damage matrices of the building envelope structures and the main load-bearing structure, which includes the influence factors such as structure type, preservation degree, building density, and interaction between different envelope components. Accordingly, based on field investigation and engineering experience, this study establishes a relevant building direct economic loss assessment model. Finally, the authors develop the Typhoon Disaster Management System to apply this loss assessment methodology to practice.

• Journal of the Korean Society of Food Culture
• /
• v.18 no.2
• /
• pp.172-180
• /
• 2003

This study was performed to document the weight loss diet practice and dietary habit related to weight control in child-bearing Korean women. The subjects were 1,434 women aged 17-39 years. The subjects were classified into 3 groups based on BMI: low weight(LW) BMI < 18.5; normal weight(NW), 18.5 BMI 22.9; and overweight(OW), 23.0 BMI. Anthropometric, general characteristics, weight control practice, and the quality of diet were assessed by a questionnaire. LW group had higher rate of smoking and drinking. They also complained more subjective symptom of anemia and used less nutritional supplementation. Weight loss diet had been practiced by about 40% of subjects and the percent was increased with increasing BMI. The reason of weight loss diet were significantly different by BMI groups(p<0.05); LW to keep body in shape, OW for health. Low BMI group had experienced more side effects after weight loss diet(p<0.05). LW group usually used inappropriate method to control weight such as skipping meals and some of OW group reported using drug to lose weight. All subjects have been skipped their meals of 3.9 times per week, especially 4.3 times in LW group. By mini dietary assessment, most of the subjects did not have regular meals. LW group tended to eat what they like and OW group preferred fried food. This study showed that child-bearing aged women make a ceaseless effort apart from their weight, and LW group have a matter of grave concern because of their dietary habit and weight control practice. Additional research should be necessary to assess the relation of health and weight loss diet in young women.

• Tribology and Lubricants
• /
• v.24 no.1
• /
• pp.21-26
• /
• 2008

A pin bush bearing is one of the most important element in the piston engine which is joined a piston to a connecting rod. A pin bush is suffered by heat and changeable repeat loads, which are come from the explosive gas heat and pressures during a reciprocating stroke. Therefore, a tribological behavior of pin bush bearings is very severe compared to other parts of a piston assembly. To keep a stable operation of pin bush bearings effectively, it would be satisfied with proper oil film strength for severe operating conditions and durability, which are strongly related to the oil film thickness, oil film pressure, and a friction loss power. The computed results show that the viscosity of engine oils slightly affects to the minimum oil film thickness and oil film pressure distribution, but is an influential parameter on a total friction loss power. Thus the low viscosity engine oils for an increased operation condition should select a high level of base oil and add a viscosity index improver as an oil film additive.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1548-1553
• /
• 2003

The design of a high speed axial piston pump for hydrostatic transmission systems requires specific understanding on where and how much its internal frictional and flow losses are generated. In this study, the frictional loss of a bentaxis type hydraulic piston pump was analyzed in order to find out which design factors influence the mechanical efficiency most significantly. To this end, the friction coefficients of the sliding components were experimentally identified by a specially constructed tribometer. Applying them to the three-dimensional dynamic model of the pump presented by Doh and Hong [1], the friction torques generated by the sliding components such as piston head , bearing and valve plate were theoretically computed. The accuracy of the computed results was confirmed by the comparison with the experimentally measured mechanical efficiency. In this paper, it is shown that the viscous friction on the valve plate and the drive shaft bearing is the primary sources of the frictional losses of the bent-axis type pump, while the friction forces on the piston contribute to them only slightly.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.2
• /
• pp.46-50
• /
• 2016

When rotating the clutch drum in the power take-off (PTO) gear box of an armored recovery vehicle, lots of inner oil is drained through the adapter by centrifugal force. Therefore, a lack of lubrication is caused by inner oil loss, and the bearing is damaged by overheating. This study, therefore, aims to design an oil-controlling adapter by using shape alteration to prevent oil loss. Both the original and improved adapters were tested at 1,800rpm by using an operational test machine. When applying the original adapter to the gear box, the bearing was damaged by overheating, which was caused by the lack of lubrication. When applying the improved oil-controlling adapter, on the other hand, it prevented the loss of inner oil. Applying the improved adapter is expected to prevent the overheating caused by lack of lubrication.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.6
• /
• pp.429-436
• /
• 2014

Most mechanical systems are now operating consistently and getting faster due to the development of automation systems. Peoples' dependence on machines have increased as when problems occur within the mechanical system, personal injury and production loss may come as a result, as most of the mechanical system's malfunctions are caused by the failure of the rotational bearing. What we need now is a maintenance system that can warn us when it detects abnormal conditions before significant damage occurs to the bearing. In this study, we have developed an acoustic emissions sensor that can figure if the bearing works under the normal condition. With this acoustic emissions sensor, we can inspect the bearing for defects by using the Heterodyne technique, which converts the ultrasound signal into audio, as a signal conditioning process.

• Steel and Composite Structures
• /
• v.41 no.5
• /
• pp.731-746
• /
• 2021

The purpose of this paper is to investigate the axial bearing capacity and residual properties of steel reinforced recycled aggregate concrete (SRC) column after elevated temperature. A total of 48 SRC columns were designed for the static loading test after elevated temperature. The variables include replacement ratios, designed temperature, target duration, thicknesses of cover concrete, steel ratios and stirrup spacing. From this test, the mass loss ratio and stress load-deformation curve were obtained, and the influence of various parameters on residual bearing capacity were analyzed. ABAQUS was used to calculate the temperature field of specimens, and then got temperature damage distribution on the cross-section concrete. It was shown that increasing of the elevated temperatures leaded to the change of concrete color from smoky-gray to grayish brown and results in reducing the bearing capacity of SRC columns. The axial damage and mechanism of SRC columns were similar to those of reinforced natural aggregate concrete columns at the same temperatures. Finally, the calculation method of axial compressive residual bearing capacity of SRC columns recycled concrete columns after high temperature was reported based on the test results and finite element analysis.

• Proceedings of the KIEE Conference
• /
• 2008.04c
• /
• pp.86-88
• /
• 2008

The rotational loss is one of the most important problems for the practical use of the high power Flywheel Energy Storage System (FESS). This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized any and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the high power FESS.

• Journal of Veterinary Clinics
• /
• v.36 no.2
• /
• pp.123-125
• /
• 2019

A 12-year-old castrated Toy Poodle was referred with a continuous non-weight bearing lameness of right hind limb due to a traffic accident 9 years ago. Physical examination and radiographs revealed partial loss of right calcaneal bone, loss of Achilles tendon and disused muscular atrophy. Arthrodesis was performed to preserve the function of the right hind limb. Pan tarsal arthrodesis plate was applied medially with 2.7 mm cortical screws and 2.0 mm cortical screws. During fixation, cancellous bone chip was transplanted into the arthrodesis site. A bone union was confirmed 9 weeks after surgery. Furthermore, on the gait analysis, the weight-bearing of right hind limb was restored to 70% of the opposite hind limb. Arthrodesis can be used to treat more difficult and serious problems affecting the joints. In particular, arthrodesis is indicated in cases such as comminuted intraarticular fractures and irreparable injury of the calcaneal tendon apparatus in the hock joint. In this case, the pan tarsal arthrodesis provided stability to the hock joint and improved the gait by restoring severe chronic damage. In conclusion, we successfully treated a challenging disability of hock joint using pan tarsal arthrodesis to restore the legs that were non-weight bearing due to chronic injury by traffic accident and objectively ascertained the increased weight bearing by gait analysis.