• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.76-77
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• 2005

• 대한예방의학회:학술대회논문집
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• 2005.10a
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• pp.485-485
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.104-108
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• 2006

논에서의 농업용수량의 산정은 많은 조사 및 연구를 통하여 정립되어 사용되고 있다. 그러나, 최근 논에서의 산정된 용수량과 실제 공급량을 비교해 보면 많은 차이를 보이고 있다. 실제 용수 공급특성 조사에 의하면 기존의 용수공급량 산정방법과 다른 몇 가지 특징을 가지고 있었다. 그중 주요한 차이점은 관개초기의 논물가두기 및 이앙기의 기간과 시기였으며 본답기간중의 중간낙수 실행여부였다. 본 연구에서는 실제 논에서의 용수공급특성에 대한 조사를 통하여, 용수공급량 산정 프로그램을 개발하고 이를 현장에 적용하는 것이다. 분석결과에 의하면 논에서의 농업용수량은 기존의 방법에 의해 산정한 값보다 약 20% 증가하는 것으로 나타났으며 본 연구에서 개발된 방법에 의해 산정된 농업용수량이 실제 용수공급패턴을 적절히 반영하는 것으로 분석되었다.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.143-150
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• 2006

Recently, in proportion to increased demand on environmentally-friendly heat source, efficient management of district heating(DH) system becomes one of important issue. The objectives of this paper are to systematize data processing of transition temperature, investigate the effect of temperature variations on thermal fatigue and find out a way to improve design fractures of Korean DH pipes. For this purpose, reliable fatigue lift evaluation procedures are examined and applied to quantify thermal fatigue lives. Also, as a prototypal optimization analysis results, mean value of original cross sectional area of selected pipes was reduced 18.6% sustaining their sufficient margins against fatigue failure. So, it is anticipated that the output of this research can be used as useful information of optimal design and operation in the future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1213-1219
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• 2001

In this paper, modeling of the multi-pass roll forming process with the finite element method and defect prediction in roll forming process are presented. In the roll forming process, there occurs the defect of scratch. It appears on tubes because of the friction between the strip and the roll, the unexpected sliding velocity and the contact pressure when fabricating the tubes. The surface of the product will be not uniform due to the defect. The scratch can be predicted with the simulation modeling of the finite element method, and can be avoided by modifying the design.

• Transactions of Materials Processing
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• v.3 no.2
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• pp.215-228
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• 1994

The purpose of this paper is to pursue a general method to determine both the flow stress of a material and the friction factor by ring compression test. The materials are assumed to obey the expanded n-power hardening rule including the strain-rate effect. Ring compression is simulated by the rigid-plastic finite element method to obtain the database used in determining the flow stress and friction factor. The Simulation is conducted for various strain hardening exponent, strain-rate sensitivity, friction factor, and compressing speed, as variables. It is assumed that the friction factor is constant during the compression process. To evaluate the compatibility of the database, experiments are carried out at room and evaluated temperature using specimens of aluminum 6061-T6 under dry and grease lubrication condition. It is shown that the proposed test method is useful and easy to use in determining the flow stress and the friction factor.

• Physical Therapy Korea
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• v.8 no.3
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• pp.107-117
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• 2001

Falls are the most serious health problems in elderly population. They are a major cause of premature death, physical injury, immobility, psychosocial dysfunction, and nursing home placement. To reduce the alarming rate of falls and related excessive mortality and morbidity, efforts must be made to detect persons at risk of falling and to prevent or reduce the frequency of falls. To facilitate such approaches, it is essential to find the cause of falling (and under what conditions) of the elderly and the factors that are associated with risk of falling. This study was aimed at designing interventions that minimize risk of falling by ameliorating contributing factors while maintaining or improving patient's mobility.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2656-2661
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• 2002

Multiple impact models to examine the effect of stress interference are proposed and investigated. The single shot model analysis, which used various shot ball conditions, was carried out to compare with multiple impacts analysis. Then the multiple impact analysis were performed to predict the effect of the shot ball distances. The results showed that the stress interference in the multiple impact model significantly reduced the maximum value of the compressive residual stresses. The residual stress profiles were strongly effected by the shot ball distances. The multiple impact model can simulate a realistic shot peening process rather than a single shot model does. It is concluded that the proposed model predicts the real process more accurately.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2670-2677
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• 2002

The ring rolling process involves three-dimensional non-steady material flow and continuous change of radius and thickness of the ring workpiece. In this study, the deformation analysis and geometric updating algorithm of the ring rolling process were verified by using the three-dimensional rigid-plastic finite element method. Manufacturing processes for plain ring and T-shaped ring were investigated by comparing experiments with simulation results, especially in side spread, load-stroke and pressure distribution, showing a good agreement. It was concluded that the simulation method would be a useful tool for the design of a ring rolling process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.382-390
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• 1995

Failure of connecting rod in automotive engine may cause catastrophic situation. The corner radius at small end has an effect on stress raising. To investigate the stress distribution in connecting rod during operation, the finite element analysis was used by giving possible maximum tension and compression. Excessive sizing after forging connecting rod may result in the tensile residual stress which lower the fatigue life and cause premature failures. It was shown that when the sizing amount is too large, the location of high tensile residual stress coincide with that of high stress amplitude during operation through the elastic-plastic finite element analysis. The endurance limit moves down due to the surface finish and decarburization, which combines with the movement of resultant stress points to dangerous range. It was concluded that the precise control of sizing and enough corner radius are necessary to a reliability of connecting rod.