• Tribology and Lubricants
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• v.13 no.3
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• pp.48-55
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• 1997

The ball bearing with thin-section raceways which is much lighter than other conventional bearings used in most modem passenger cars and small tracks. The important design parameters of this bearing is the groove radius of raceways, the diametral clearance, the free contact angle and so on. The optimal value of these parameters were determined by considering the dynamic load capacity, the contact angle and the calculated fatigue life. The contact angle between a ball and raceways was calculated by considering the local contact deformation and the structural deformation of thin-section raceways which was estimated by FEM. The raceways were made by means of the press-forming process. The fatigue life tester was designed and manufactured. The fatigue life test was executed and the reliability of this bearing was confirmed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.344-351
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• 2003

In order to consider the characteristics of nonlinear dynamic responses of seismic isolated bridges reasonably, piers and isolators are modeled as a 2-DOF bilinear system. Then nonlinear time-history earthquake response analysis is accomplished many artificial input ground motions which were generated to reflect the characteristics of earthquakes. Damage probabilities and failure probabilities of each structural elements of the brides are calculated by using Monte-Carlo simulation method. Based on LCC evaluation considering various cost items of direct/indirect damage costs, the optimal design method of seismic isolated bridges is proposed. By using a sensitivity analysis about the design variables and a cost effectiveness evaluation in the viewpoint of LCC, the validity and the adequacy of proposed optimal design method are verified.

• Interaction and multiscale mechanics
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• v.4 no.1
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• pp.65-83
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• 2011

In this study, two extreme cases of compatibility of the horizontal displacements between the foundation and soil are considered, for which the pressure and settlements of the isolated footings and member end actions in structural elements are obtained using the three dimensional models and numerical experiments. The first case considered is complete slip between foundation and soil, termed as the un-coupled analysis. In the second case of analysis, termed as the coupled analysis, complete welding is assumed of joints between the foundation and soil elements. The model and the corresponding computer program developed simulate these two extreme states of compatibility giving insight into the variation of horizontal displacements and horizontal stresses and their intricacies, for evaluation of the influence of using the interface elements in soil-structure interaction analysis of three dimensional multiscale structures supported by isolated footings.

• Journal of the Korean Society for Railway
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• v.7 no.1
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• pp.32-36
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• 2004

Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Static load test has been performed up to date to assess structural safety of the carbody. However, static load test is not sufficient to evaluate fatigue strength of the carbody, because fatigue failure is caused by dynamic load. In this study, the established load test methods for carbody are described and the characteristics of the methods are discussed. Also, a testing method to simulate dynamic loading condition is proposed for evaluation of fatigue strength of the carbody. The results by the proposed testing method are compared with the results by the static load test and new findings are discussed.

• Structural Engineering and Mechanics
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• v.25 no.6
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• pp.653-674
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• 2007

This paper discusses the application of piezoelectric sensors used for evaluation of damping ratio of PVC plastics. The development of the mathematical formulation based on the Empirical Mode Decomposition for calculating the damping coefficient and natural frequency of the system is presented. A systematic experimental and analytical investigation was also carried out to demonstrate the integrity of several methods commonly used to evaluate the damping of materials based on a single degree freedom formulation. The influence of the sensors' location was also investigated. Besides the commonly used methods, a newly emerging time-frequency method, namely the Empirical Mode decomposition, is also employed. Mathematical formulations based on the Hilbert-Huang formulation, and a frequency spacing technique were also developed for establishing the natural frequency and damping ratio based on the output voltage of a single piezoelectric sensor. An experimental investigation was also conducted and the results were compared and verified with Finite Element Analysis (FEA), revealing good agreement.

• Earthquakes and Structures
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• v.20 no.1
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• pp.13-27
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• 2021

A new seismic design methodology has been developed for precast concrete diaphragms. Seismic design factors were used to be applied on top of diaphragm seismic design forces in the current code. These factors, established through extensive parametric studies, align diaphragm design strengths with different seismic performance targets. A simplified evaluation structure with a single-bay plan was used in the parametric studies. This simplified evaluation structure is reasonable and cost-effective as it can comprehensively cover structural geometries and design parameters. However, further verification and investigation are required to apply these design factors to prototype structures with realistic layouts. This paper presents diaphragm design of several precast concrete office buildings using the new design methodology. The applicability of the design factor to the office building was evaluated and verified through nonlinear time history analyses. The seismic behavior and performance of the diaphragm were investigated for the precast concrete office buildings. It was found that the design factor established for the new design methodology is applicable to the realistic precast concrete office buildings.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.10
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• pp.191-198
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• 2019

In this paper the evaluation scheme for determining torsional irregularity of Hanok has been proposed. The proposed method can evaluate torsional irregularity of Hanok easily only with characteristics of Hanok shapes, arrangement of lateral load resisting frames and their lateral stiffness without time consuming and complicate 3-dimensional structural analysis. The proposed formula is expressed as allowable maximum eccentricity, and torsional irregularity is evaluated by comparing this value with actual eccentricity. The applicability of the proposed scheme was evaluated by applying it to the line shape plan Hanok with two symmetrically arranged walls and the result was expressed by formula and graph. The results showed that the allowable maximum eccentricity is 10% of plan dimension perpendicular to the seismic load when the walls are placed at the extreme end. The proposed formula was expressed as a generalized formula so it can be applied generally to the various plan shape and wall arrangement of Hanok.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.1
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• pp.7-15
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• 2021

Buckling of cylindrical structures has been extensively researched, because it is an important phenomenon to be considered in structural design. However, the evaluation of thermal effects on the buckling of cylindrical structures has been insufficient; therefore, this study evaluates this thermal effect using shell elements. In addition, the thermal effect on the buckling of temperature-dependent nonlinear materials was evaluated. Nonlinear and linear buckling analyses were performed using the arc-length method to investigate the behavioral characteristics of a cylindrical structure. The basic theory of the linear buckling analysis of a cylindrical structure subjected to thermal stress was derived and presented by applying the thermal stress basic theory.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.2
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• pp.151-164
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• 2021

With the gradual increase in the ROK naval power, it is an undeniable fact that the time of operation in the ice-infested area will be necessary in the near future. Recently, cases of ice formation around Korean waters in wintertime have been frequently reported. However, in the case of the ROK naval vessels to date, it is a fact that the ice-strengthened perspective has not been considered from the design stage. In this study, the capability of operation in the ice-infested area of the ROK naval vessels, which did not take into account the ice-strengthened design, was reviewed through the evaluation of the vessel's structural integrity in accordance with the sea ice conditions.

• Journal of the Korean GEO-environmental Society
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• v.23 no.1
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• pp.15-23
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• 2022

This paper presents the results of full-scale load tests performed frictional anchors to various lengths at several sites in Korea. Various rock types were tested, ranging from highly weathered shale to sound gneiss. In many tests, rock failure was reached and the ultimate loads were recorded along with observations of the shape and extent of the failure surface. Laboratory tests were also conducted to investigate the influence of the corrosion protection sheath on the bond strength. Based on test results, the main parameters governing the uplift capacity of the rock anchor system were determined. By evaluation of the ultimate uplift capacity of anchor foundations in a wide range of in situ rock masses, rock classification suitable for structural foundation was developed. Finally, a very simple and economical design procedure is proposed for rock anchor foundations subjected to uplift tensile loads.