• New & Renewable Energy
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• v.6 no.3
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• pp.39-46
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• 2010

With growing of wind turbine industry, offshore wind energy is getting more attention in recent years. Among all the components of offshore wind turbines, the foundation of the offshore wind turbine plays a key role in stability of whole system. In this work, the 5 MW NREL reference wind turbine with rated speed of 11.4 m/s is used for load calculation. Wind and wave loads are calculated using GH-Bladed (Garard Hassan) and FAST (NREL). Additionally, FE simulation is carried out to investigate the wave effect on the support structure. Meanwhile, this work is to simulate systemic and optimized load cases for the foundation analysis of wind turbine system.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.618-626
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• 2011

The characteristics of construction work cause excessive strain on specific body parts of the construction craft workers. However, there are few tools to mane an accurate measurement of the load on the musculoskeletal system, and the musculoskeletal disorders (MSDs) experienced by the workers have not been properly understood. So, there is an urgent need for development of a tool to measure the load on the musculoskeletal system. Therefore, this research aims to develop a musculoskeletal load measuring device for construction workers. In order to eliminate the noise and errors, an accelerometer, gyro sensors and the Kalman Filter are used in the device developed in this research.

• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.185-189
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• 2012

Objective: The aim of this paper is to introduces Hyundai Heavy Industry's ergonomic risk assessment tool, H-OWAS, which is considering work load and frequency compared to the OWAS. Background: As prevalence of work-related musculoskeletal disorders(WMSDs) in ship building industries has been much higher than that in other industries, most of the large scaled corporations have implemented their own prevention program since legislation on the prevention of WMSDs had introduced in 2003. Method: This paper introduces WMSDs prevention program, HEMP(HHI Ergonomics Management Program) which consists of risk assessment, improvement efforts of working environments, medical treatment and training/evaluation and describes how to operate the program. We also describe application of OWAS method considering work load and frequency for risk factor analysis(H-OWAS) and shows methodology for assessing the ergonomic risk factor. And comparison of the assessment results between OWAS and H-OWAS is carried out by statistical analysis. Result: There was statistically significant difference in the assessment results between OWAS and H-OWAS, and regression shows H-OWAS explains the borg's scale of perceived exertion more clearly than OWAS. Conclusion: H-OWAS has been proved more effective tool than OWAS to evaluate ergonomic risk factor under real working condition. Application: H-OWAS can be widely applied to the many other companies when implementing the ergonomics risk assessment.

• Journal of Korean Academy of Nursing Administration
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• v.18 no.4
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• pp.383-393
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• 2012

Purpose: The aim of this study was to investigate the effects of occupational stress and coping styles on burnout of clinical nurses. Methods: The participants in this study were 397 nurses, working at the hospitals in Seoul, Gangwon, and Gyongbuk provinces. Data were collected using a structured questionnaire from November, 2009 to January, 2010. The SPSS WIN 13.0 version program was used for data analysis. Results: The most significant predictors of burnout were positive reappraisal and work load. Work load, resource inadequacy, role ambiguity, and indifference coping style positively correlated with burnout. Positive reappraisal and problem-focused coping styles negatively correlated with burnout. Conclusion: The study results indicate that it is important to reduce work load, resource inadequacy, and role ambiguity in nurses and to strengthen their positive reappraisal and problem-focused coping styles to prevent burnout. This could be achieved with job redesign, modification of shift work systems, and by offering burnout prevention program.

• Journal of Drive and Control
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• v.17 no.2
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• pp.9-18
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• 2020

The purpose of this study was to analyze the effect of the soil cone index (CI) on the tractor work load. A load measurement system was constructed for measuring the field data. The field sites were divided into grids (3×3 m), and the cone index was measured at the center of each grid. The work load measured through the plow tillage was matched with the soil cone index. The matched data were grouped at 600 kPa intervals based on the cone index. The work load according to the cone index was analyzed for engine, axle, and traction load, respectively. The results showed that when the cone index increased, engine torque decreased by up to 9%, and the engine rotational speed and brake-specific fuel consumption increased by up to 5% and 3%, respectively. As the cone index increased, the traction and tillage depth were inversely proportional to the cone index, decreasing 7% and 18%, respectively and the traction and tillage depth were directly proportional to the cone index, increasing 13% and 12%, respectively. Thus, it was found that the cone index had a major influence on the engine, axle, and traction loads of the tractor.

• Journal of the Korean Home Economics Association
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• v.31 no.3
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• pp.75-87
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• 1993

The purpose of this study is to analyze the variables related to household work and to find the methods to increase it. The data using in-depth interview method was collected. 30 homemakers were sampled, and the frequency and interview contents were presented. The major findings were as follows: 1. 18 out of 30 interviewees were satisfied with their household work, but they just accepted their given lives. 2. Changes in socialization for woman, general images of household work and women's perception to their work rather than reduction of work load are needed. 3. When women choose the household work as their job, their satisfaction will be increased.

• Journal of Families and Better Life
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• v.17 no.3
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• pp.83-92
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• 1999

Many Policies were made to increase women's employment since the latter half of the 1980s in Korean. But work-family conflict of married women can not be solved without reducing the household work load, because all of Korean wives have the responsibilities of household work. So this study aims to establish the supporting system of household work in the women's policies. For this purpose this study examine the actual conditions for supporting the household work. And supporting system and strategies for policy making related to household work and suggested. Supporting system includes arrangement in household raise in social consciousness improvement of market circumstance establishment of relating acts and public facilities.

• Journal of Power Electronics
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• v.18 no.4
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• pp.975-984
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• 2018

This work presents a high efficiency phase shifted full bridge (PSFB) DC-DC converter for use in the second stage of a battery charger for neighborhood electrical vehicle (EV) applications. In the design of the converter, Lithium-ion battery cells are preferred due to their high voltage and current rates, which provide a high power density. This requires wide range output voltage regulation for PSFB converter operation. In addition, the battery charger works with a light load when the battery charge voltage reaches its maximum value. The soft switching of the PSFB converter depends on the dead time optimization and load condition. As a result, the converter has to work with soft switching at a wide range output voltage and under light conditions to reach high efficiency. The operation principles of the PSFB converter for the continuous current mode (CCM) and the discontinuous current mode (DCM) are defined. The performance of the PSFB converter is analyzed in detail based on wide range output voltage and load conditions in terms of high efficiency. In order to validate performance analysis, a prototype is built with 42-54 V / 15 A output values at a 200 kHz switching frequency. The measured maximum efficiency values are obtained as 94.4% and 76.6% at full and at 2% load conditions, respectively.

• Journal of the Ergonomics Society of Korea
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• v.23 no.4
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• pp.45-56
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• 2004

The purpose of this study is to evaluate perceived discomfort of working postures in terms of upper body (back, shoulder, and elbow) flexions when an external load varies. Eighteen subjects participated in an experiment of appraising perceived discomfort of varying upper body postures with three levels of external loads given. The ANOVA results showed that the perceived discomfort of upper body postures was significantly affected by the external load. It was also apparent that the interactions between external load and upper body posture were significant (p< 0.001). The result implies that a new posture classification scheme for workload assessment methods may be in need to reflect such interactions between external load and upper body posture. In order to support the statement, a regression model of perceived discomfort of upper body postures obtained from the experiment was developed and compared to that of perceived discomfort of seven work-related postures found in automobile assembly operations. The correlation coefficient between predicted and actual values of perceived discomfort was about 0.96. It is expected that the result help to properly estimate the body stress resluting from worker's postures and external loads and can be used as a valuable design guideline on preventing work-related musculoskeletal diseases in industry.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.523-528
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• 2001

In this study we tried to determine the work-hardening exponent using continuous indentation test. Work-hardening exponent, which was determined by Hollomon equation, in tensile test, is an important parameter to determine plastic deformation and brittle/ductile property of materials. For using Hollomon equation, true stress and true strain were defined by indentation depth and indentation load. Using them the new equation, which is constituted by indentation depth, indentation load and work-hardening exponent, was induced. Indentation depth was calibrated because of elastic deflection and pile-up/sink-in phenomena. Work-hardening exponents of various steels derived by it showed good agreement to the results of tensile tests. In addition to experiments, FEM simulation was accomplished to investigate changes of real contact depth with materials properties changes. Through this simulation it is concluded that the real contact depth is changed by Y/E value which affect the early stage of indentation, and work-hardening exponent which the latter stage.