• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2014.05a
• /
• pp.188-189
• /
• 2014

Recently, structural system of apartment building is changing from wall type to column type to accommodate various life styles of residents in Korea. Reinforced-concrete bearing wall structures have been mainly used in apartment construction since 1980's. It is impossible to remove the bearing wall in case of remodeling a house, so that the lightweight wall is needed to apply to the column type structure of the Long Life Housing. Therefore, the purpose of this study is to evaluate the construction performance of the wall. Constructibility reviews are performed throughout interview survey from builders who charge with managing the construction of the lightweight wall in field. This paper present that constructor prefer the bearing wall rather than the lightweight wall because of the schedule delay, difficulty of management, and lack of skilled labor. The results indicate what we should improve on the lightweight wall from now on.

• Journal of the Korean Society of Industry Convergence
• /
• v.24 no.6_2
• /
• pp.819-825
• /
• 2021

In the industry, the use of lightweight bearings is increasing to minimize motor power loss, and in particular, the application of next-generation systems such as robots and drones is increasing. Bearing manufacturers are producing lightweight bearings by changing the bearing material, but related researches is insufficient. In this paper, life test and structural analysis were performed for lightweight bearings, and shape parameters and scale parameters were derived based on the life test results. It was confirmed that the shape parameter was 2.52 and the scale parameter was 164 hours. As a result of calculating the dynamic load rating based on the B₁₀ life, it was confirmed that the dynamic load rating of the lightweight bearing was 7% compared to the formula suggested by ISO 281. The reason is that the material of the retainer, which is a major failure part, is a polyamide 66 series that reacts sensitively to heat, so It is judged to show a lot of difference from the ISO 281 calculation formula.

• Tribology and Lubricants
• /
• v.29 no.6
• /
• pp.386-391
• /
• 2013

Part I of this study analyzed the effects of tilting pad bearing designs to reduce the stiffness of the bearings used in a process high-speed lightweight centrifugal compressor intended for a domestic refinery use. This was done in an attempt to enhance the robustness of its rotordynamic stability against possible aerodynamic cross-coupled stiffness. The bearing design variables reviewed were the clearances, LBPs, LOPs, and preloads. The results showed that there was practically no difference between the LBP and LOP designs in terms of the bearing stiffness, because the compressor rotor was lightweight and the bearings had relatively high preloads. Increasing both the machined and assembled clearances in bearing designs has resulted in the bearing stiffness being greatly reduced. In addition, it has been confirmed that an additional reduction in the bearing stiffness can be obtained for given fixed machined clearances by decreasing the preloads, i.e., by increasing the assembled clearances.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.05a
• /
• pp.185-186
• /
• 2015

The use of non-bearing lightweight wall has increased recently due to the increase of high-rise buildings and supply of long-life housing. Lightweight wall has advantages such as reducing the self-weight of the building, convenience in installation, and shortening construction period, however, must have a sufficient strength to external force. This study standardized the stiffness (static horizontal load resistance) test method for lightweight walls by using the actual impact load obtained through the load analysis test conducted in the previous studies. The size of specimen was set up as height 2.4m and width 3.0m. Test apparatus and test methods were referred to BS 5234-2:1992. However, the loading level applied to the specimen was divided into 3 steps (3000N, 1000N, 500N) that can be applied selectively depending on the purpose of the wall. The deformation characteristics according to the same loading level were vary depending on the specimen's type, and the evaluation criteria for functional damage may vary depending on the material, method of construction, and purpose of wall. Therefore, we did not suggest unified evaluation criteria of the stiffness to the test results.

• Journal of the Korean GEO-environmental Society
• /
• v.7 no.5
• /
• pp.21-29
• /
• 2006

Light weight filling method prevents settlement of ground by decreasing the weight of fills. This method is increasingly used for it's convenience and workability. Styrofoam is increasingly used as a lightweight filling material in soft ground. The beneficial effects of the use of EPS derive from minimizing the stress increment, increasing the bearing capacity and reducing the settlement. For this study, model test and FEM analysis of bearing capacity is carried out composing two-layered ground with clay in the lower layer and lightweight filling material in upper layer. Based on the results obtained here in this study, it is concluded that the use of recycled EPS beads is acceptable lightweight fill. Light weight fills used for disposal is superior to typical embankment fills in bearing capacity.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.5
• /
• pp.1-7
• /
• 2012

The transportation is almost dependent on a single fuel petroleum with transportation energy dilemma. Hybrid Electric Vehicle(HEV) technology holds more advantages on efficiency improvements for petroleum consumption at the transportation. And bearing is recognized as the important component of gearbox. Gearboxes for HEV transmission have been ensured the highest reliability over some years in withstanding high dynamic loads. At the same time, the demands of lightweight design and cost minimization are required by thought-out design, high-quality material, superior production quality and maintenance. In order to design a reliable and lightweight gearbox, it is necessary to analyze bearing rating life methods between standard and different bearing companies with calculation methods for modification factors. In this paper, the influence of life time of bearings will be pointed out. Bearing contact stress and load stress distribution of HEV gearbox are obtained and compared with Romaxdesigner and BearinX. And the unequal wear of the left bearing for the gearbox intermediate shaft is investigated between simulation and test.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.4
• /
• pp.25-30
• /
• 2012

The transportation is almost dependent on a single fuel petroleum with transportation energy dilemma. Hybrid Electric Vehicle(HEV) technology holds more advantages on efficiency improvements for petroleum consumption at the transportation. And bearing is recognized as the important component of gearbox. Gearboxes for HEV transmission have been ensured the highest reliability over some years in withstanding high dynamic loads. At the same time, the demands of lightweight design and cost minimization are required by thought-out design, high-quality material, superior production quality and maintenance. In order to design a reliable and lightweight gearbox, it is necessary to analyze bearing rating life methods between standard and different bearing companies with calculation methods for modification factors. In this paper, the influence of life time of bearings will be pointed out. Bearing contact stress and load stress distribution of HEV gearbox are obtained and compared with Romaxdesigner and BearinX. And the unequal wear of the left bearing for the gearbox intermediate shaft is investigated between simulation and test.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.3 s.76
• /
• pp.253-262
• /
• 2005

Because the framed wall system using steel studs and runners with square steel tubes as structural elements is reinforced by the horizontal members called runners, it has more strength and load bearing capacity than the steel house wall system. Also, this system improves adiabatic and sound insulation performance by filling up the autoclaved lightweight concrete. We need to evaluate load bearing capacity according to the axial load and lateral load in case this system is applied in the housing system with 3~5 stories through variations in intervals for the runners under the placement effect of autoclaved lightweight concrete. Therefore, this study seeks to analyze axial and shear behavior of the framed wall system according to the placement effect of autoclaved lightweight concrete, and to secure safety for the vertical and lateral loads.

• Steel and Composite Structures
• /
• v.50 no.6
• /
• pp.675-688
• /
• 2024

Cold-formed steel (CFS) is prone to buckling failure under loading. Lightweight concrete (LC) made of lightweight aggregate has light weight and excellent thermal insulation performance. However, concrete is brittle in nature which is why different materials have been used to improve this inherent behavior of concrete. The distortional buckling (DB) performance of cold-formed steel-lightweight concrete (CFS-LC) composite columns was investigated in this paper. Firstly, the compressive strength test of foam concrete (FC) and ceramsite concrete (CC) was carried out. The performance of the CFS-LC members was investigated. The test results indicated that the concrete-filled can effectively control the DB of the members. Secondly, finite element (FE) models of each test specimen were developed and validated with the experimental tests followed by extensive parametric studies using numerical analysis based on the validated FE models. The results show that the thickness of the steel and the strength of the concrete-filled were the main factors on the DB and bearing capacity of the members. Finally, the bearing capacity of the test specimens was calculated by using current codes. The results showed that the design results of the AIJ-1997 specification were closer to the experimental and FE values, while other results of specifications were conservative.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.5
• /
• pp.21-27
• /
• 2014

Currently, wind power has become a major research field in the area of sustainable development. As one important component of a wind turbine transmission system, most instances of downtime due to a gearbox failure are caused by bearing failures. Gearboxes for wind turbines must have the highest levels of reliability over a period of approximately 20 years, withstanding high dynamic loads. At the same time, a lightweight design and cost minimization efforts are required. These demands can only be met with a well-thought-out design, high-quality materials, a high production quality and proper maintenance. In order to design a reliable and lightweight gearbox, it is necessary to analyze methods pertaining to the bearing rating lifetimes of the standard and of different companies, also including calculation methods for modification factors. This can determine the influence of the bearing lifetime.