• Journal of the Korean Society for Railway
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• v.11 no.1
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• pp.33-38
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• 2008

To reduce the cost and time of transport in Eurasian railroad networks such as TKR, TCR and TSR owing to the problem of different track gauges (narrow/standard/broad gauge), it is important to develop the gauge-adjustable wheelset system to adapt easily to these gauges. Moreover, freight trains having the gauge-adjustable wheelsets should be passing various curved tracks in railroad networks. Therefore, to assure the safety of the gauge-adjustment whellset system, it is necessary to evaluate integrity of locking parts in the system using stress analysis. This study is focused on analyzing contact stress of locking parts by using FEA(finite element analysis) simulation during the gauge changeover operation and freight trains' service in the curved track, respectively.

• Journal of Korean society of Dental Hygiene
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• v.18 no.1
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• pp.43-53
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• 2018

Objectives: The aims of this study were to analyze the job stress of clinical hygienists according to their positional system and to confirm its relevance. Methods: Seven hundred seventy six clinical dental hygienists participated in this survey. The questionnaire items consisted of general characteristics, working environment, and job stress. The data analysis was performed using IBM SPSS statistics ver.23.0 software. Results: Among the job stresses, the stress on the job demands was the highest with 63.4 points, and the stress on interpersonal conflict was the lowest with 34.6 points. The total score of job stress was the highest in the 26-30 year-old age group, and major stress factors in this group were job insecurity, organizational system, and lack of reward. Team members were more stressful about insufficient job control, organizational system, and lack of reward than team managers, while team managers were more likely to score interpersonal conflict. The dental hygienists in the hospitals that did not have the positional system got more stressed in the insufficient job control, organizational system, and lack of reward area. Conclusions: The presence of positional system was related to job demand, insufficient job control, organizational system, and lack of reward. Structural efforts such as establishing a proper positional system in dental clinics will be needed to control job stress in the clinical dental hygienists.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.70-75
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• 2010

The aim of this study is to evaluate the axial residual stress in multi-pass drawn high carbon steel wire by using FE analysis and XRD. When FE analysis is applied to evaluate the residual stress in drawn wire of multi-pass drawing process, obtaining the reliable effective stress-strain curve at high strain is very important. In this study, a model, which can express the reliable effective stress-strain curve at high strain, is introduced based on the Bridgman correction and tensile test for multi-pass drawn high carbon steel wires. By using the introduced model, FE analysis was carried out to evaluate the axial residual stress in the drawn wires. Finally, the effectiveness of the FE analysis with the introduced stress-strain relation was verified by the measurement of residual stress in the drawn wires through XRD. As a result, the evaluated residual stress of FE analysis shows good agreement with the measured residual stress.

• 연구논문집
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• s.27
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• pp.57-73
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• 1997

The bogie between the track and the railway vehicle body, is one of the most important component in railroad vehicle. Its effects on the safety of both passengers and vehicle itself, and on the overall performance of the vehicle such as riding quality, noise and vibration are critical. The bogie is mainly consisted of the bogie frame, suspensions, wheels and axles, braking system, and transmission system. The complex shapes of the bogie frame and the complicate loading condition (both static and dynamic) induced in real operation make it difficult to design the bogie frame fulfilling all the requirements. The complicated loads applied to the bogie frame are i) static load due to the weight of the vehicle and passengers, ii) quasi-static load due to the rolling in curves iii) dynamic load due to the relative motion between the track, bogie, and vehicle body. In designing the real bogie frame, fatigue analysis based on the above complicated loading conditions is a must. In this study, stress analysis of the bogie frame has been performed for the various loading conditions according to the UIC Code 6 15-4. Magnitudes of the stress amplitude and mean stress were estimated based on the stress analysis results to simulate the operating loads encountered in service. Fatigue strength of the bogie frame was evaluated by using the constant life diagram of the material. 3-D surface modelling, finite element meshing, and finite element analysis were performed by Pro-Engineer, MSC/PATRAN, and MSC/NASTRAN, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.1
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• pp.160-166
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• 2005

In this paper, the combined system equation of motion, which can analyze the dynamic interaction between pantograph and catenary system, is derived by adopting absolute nodal coordinates and rigid body coordinates. The analysis results are compared with real experiment data from test running of Korean high-speed train (HSR 350x). In addition, a computation method for the dynamic stress of contact wire is presented using the derived system equation of motion. This method might be good example and significant in that the structural and multibody dynamics model can be unified into one numerical system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.400-408
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• 1992

In this paper, analysis of temperature and stress distributions in the roll for a twin roll continuous casting process was carried out. Firstly, several state equations were set up to determine the temperature distribution in the roll using finite difference method. Secondly, thermal stress in the roll was calculated numerically. Also, stress distribution due to the roll pressure was calculated to determine the effect of the roll pressure. For analysis of temperature distributions and the stress states of the roll, there are three kinds of roll materials, 2ICrMoV5. 11, CuCo/NiBe, CuCrZr and three types of cooling system were used.

• Proceeding of KASS Symposium
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• 2005.05a
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• pp.89-98
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• 2005

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. Therefore membrane structures arc unstable structures initially. These soft structures need to be introduced initial stresses first because of its initial unstable state, and it happens large deformation phenomenon. To find the structural shape after large deformation caused by initial stiffness introduced, we need the shape analysis considering geometric nonlinearity in structural design procedure. In this study, we investigate into the stress concentration at crack of membrane structures. Therefore, using the nonlinear analysis program that NASS (Nonlinear Analysis for Spatial Structures) perform nonlinear analysis, and stress distribution for creak length investigate for using linear elastic fracture mechanics.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.34-41
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• 2005

For assessing residual lift of the steam pipe in fossil power plants, inspections and analysis are usually focused on the critical locations such as butt welds, elbows, Y-piece and T-piece of the steam pipes. In predicting the residual life of T-piece, determination of local stress near welds considering system load as well as internal pressure is not a simple problem. In this study, stress analysis of a T-piece pipe was conducted using a three-dimensional model which represents the T-piece of a domestic fossil power station. Elastic and elastic-creep analysis showed the maximum stress level and its location. Residual creep rupture life was also calculated using the stress analysis results. It was argued that the calculated life is reasonably same as the measured one. The stress analysis results also support life prediction methodology based on in-field replication technique.

• Nuclear Engineering and Technology
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• v.45 no.2
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• pp.249-256
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• 2013

In accordance with the US Nuclear Regulatory Commission (US NRC), Regulatory Guide 1.20, the reactor vessel internals comprehensive vibration assessment program (RVI CVAP) has been developed for an Advanced Power Reactor 1400 (APR1400). The purpose of the RVI CVAP is to verify the structural integrity of the reactor internals to flow-induced loads prior to commercial operation. The APR1400 RVI CVAP consists of four programs (analysis, measurement, inspection, and assessment). Thoughtful preparation is essential to the measurement program, because data acquisition must be performed only once. The optimized design of a vibration and stress measurement system for the RVI CVAP is essential to verify the integrity of the APR1400 RVI. We successfully designed a vibration and stress measurement system for the APR1400 RVI CVAP based on the design materials, the hydraulic and structural analysis results, and performance tests of transducers in an extreme environment. The measurement system designed in this paper will be utilized for the APR1400 RVI CVAP as part of the first construction project in Korea.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.191-195
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• 2018

By using an ANSYS product suite (CFX, Ansys Multiphysics), which is a powerful tool for multiphysics analysis of complicated physical phenomena, we performed a structural stress analysis based on fluid flow and heat transfer phenomena within a quick connect/disconnect (QC/DC) bellows system. Considering the extremely low temperatures in the QC/DC environment, an approach to the problem based on complex multi-physics phenomena, where different phenomena interact with each other, is crucial. Therefore, we use a numerical analysis technique where fluid-thermal-structural interactions are combined. In conclusion, when low temperature fluids flow inside bellows, the expected service life is conspicuously reduced due to the thermal stress caused by heat transfer. Therefore, in future research, a structure with considerably reduced thermal stress by robust design optimization will be derived.