• 대한기계학회논문집A
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• 제29권8호
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• pp.1085-1092
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• 2005

The OHT(Over Head Transportation) Vehicle transports heavy products quickly and repeatedly at the industrial workplace. The belt in the OHT vehicle is used to support the weight of the OHT Cage. The fatigue of the belt is caused by the dynamic load during the operation time. Since the fatigue fracture of the belt affects the safety at the workplace, the correct prediction of the dynamic load is necessary to calculate the fatigue life of the belt on the design step. In this paper a computer aided analysis method is proposed for the belt in the early design stage using dynamic analysis, stress analysis, belt tensile test, belt fatigue test and fatigue lift prediction method. From the dynamic load time histories and the stress of the belt FE model, a dynamic stress time history is produced. Using linear damage law and cycle counting method, fatigue life cycle is calculated. The method developed in this paper is used to reduce the time and cost for designing the OHT belt in different environment and condition.

• 한국기계가공학회지
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• 제3권1호
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• pp.72-78
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• 2004

In this paper, mechanical behaviors of developed pedicle screw system, made of bio-mechanical materials(Ti-6Al-4V, Grade 5), ale predicted using FEM analysis. As a first step, morphologic construction of normal Korean spines and surgical operation convenience are considered to design optimum pedicle screw system. In this step, various design variables are considered as design parameters to develop optimized models. As a next step, tension and bending tests are performed to improve the structural performance of the developed system using finite element method. In this step, required Static compression and bending test specifications by ASTM F-04 25 04 01 are applied to understand the bio-mechanical behaviors of the designed spinal implant system under various load types. As the results of this research, it is possible to develop efficient pedicle screw system, having enough rigidity and fixation to stand any spinal damage under allowable stress conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1318-1319
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• 2011

In this paper, we analyzed of growth and electrical characteristics of micro-cracks with thermal effect in PV module. The micro-cracks are increasing the breakage risk over the whole value chine from the wafer to the finished module, because the wafer or cell is exposed to mechanical stress. we experimentally analyze the direct impact of micro-cracks on the module power and the consequences after artificial aging. The first step, we made micro-cracks in PV module by mechanical load test according to IEC 61215. Next, PV modules applied the thermal cycling test, because microcracks accelerated aging by thermal cycling test. according to IEC61215. Before every test, we checked output and EL image of PV module.

• 한국환경복원기술학회지
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• 제5권4호
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• pp.19-30
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• 2002

The stability of slope using root-pile like to the reinforcements is affected by the interaction behavior mechanism of soil-reinforcements. Through the studying on the interaction in joint of its, therefore, the control roles can be find out in installed slope. In study, the stress level ratio based on the insert angle of installed reinforcements in soil used to numerical analysis, which was results from the duty direct shear test in Lab. The maximum shear strain variation on the reinforcements was observed at insert angle, which was approximately similar to the calculated angle based on the equation proposed by the Jewell. The elasto-plastic joint model on the contact area of soil-reinforcements was presumed, the reinforced soil assumed non-linear elastic model and the reinforcements supposed elastic model, respectively. The finite element analysis of assumed models was performed. The shear strain variation of non-reinforced state obtained by the FEM analysis including elasto-plastic joint elements were shown the rationality of general limit equilibrium analysis for the slope failure mode on driving zone and resistance zone, which based on the stress level step according to failure ratio. Through the variation of shear strain for the variation of inserting angle of reinforcements, the different mechanism on the bending and the shear resistance of reinforcements was shown fair possibility.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.244-251
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• 2003

A two-dimensional BEM code, $FRACOD^{2D}$, was applied to simulate fracture initiation and propagation processes in a rock pillar during an in situ heater test of a rock pillar planned at the $\"{A}sp\"{o}$ Underground Rock laboratory of SKB, in Southern Sweden. To take the advantage of conventional BEM for simulating fracturing processes, but without efforts for domain integral transformation, a hybrid approach is developed to simulate the fracturing processes in rock pillar under coupled thermo-mechanical loading. The code FRACOD was used for simulating the fracture initiation and propagation processes with its boundary tractions reflecting the effects of the initial and redistributed thermomechanical stresses in the domain of interest at multiple excavation and heating steps were produced by a special algorithm of stress inversion, based on resultant thermo-mechanical stress fields at each excavation and heat loading step by a FEM code without considering fracturing processes. This hybrid approach can take the advantages of both types of numerical methods and avoids their shortcomings for fracturing process simulation and domain effects, respectively. In this paper, we present the hybrid approach for the stress, displacements, and fracturing processes at sequential excavation and heating steps of the in situ heater test as a predictive modelling, the formulation of the fracturing models and the predictive results. Two sections of borehole depth, 0.5 m and 1.5 m below the tunnel floor are considered. The pillar area is modelled with the FRACOD and the stress field produced by excavation and heating is transferred with corresponding boundary stresses. From the modelling results, the degree of fracturing and damage are evaluated for 120 days of heating. Dominated shear fracturing in the vicinity of the central pillar was observed from the models at both sections, but spalled area appears to be limited. Based on the modelling results, a sensitivity study for the effect of pre-existing fractures in the vicinity of the holes is also conducted, and the initiation and evolution of EDZ around the deposition holes are investigated using this particular numerical technique.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1984년도 학술대회지
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• pp.97-105
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• 1984

홍삼 추출물이 스트레스에 노출된 생쥐의 행동에 미치는 영향을 다음과 같은 실험을 통하여 연구하였다. 1. 줄타기 테스트와 같은 강제적 운동 2. 매달리기와 같은 스트레스에 노출된 생쥐의 기억력의 감퇴 및 직장 체온의 변화 3. 매달리기와 같은 만성적 스트레스에 노출된 생쥐의 성행동능과 학습행동능 4. 매달리기와 같은 만성적 스트레스에 노출된 성숙한 암컷쥐의 성주기 변화 5. $40{\%}$의 알콜을 투여한 후 rotar-rod및 step-through테스트를 통한 운동자율능과 수동성 시도 기피반응 홍삼의 투여는 경구투여 방법을 택하였다. 1. 강제적 운동을 시키기 전에 인삼을 투여하면, 강제적 운동수행능이 증가되었다. 2주동안 하루에 1회 강제적 운동을 시킨 후 바로 인삼을 투여하면. 생쥐의 강제적 운동수행능의 감소가 억제되었다. 2. 4일동안 하루에 1회 스트레스에 노출시킨 후 인삼을 경구 투여하면 step-through와 step-down 테스트에 대한 수동성 기피반응의 쇠퇴를 지연시켰으며, 직장온도의 감소를 억제하였다. 3 인삼투여는 성능력의 감퇴와 수동성 기피반응 수행능의 감퇴를 개선하였고. 수동성 기피반응의 쇠퇴를 지연시켰다. 인삼의 투여는 스트레스에 노출된 후 하루에 한번씩 2주동안 투여하였다. 4. 인삼투여로 스트레스에 의한 성주기의 파괴와 직장온도가 감소되는 것이 방지되었다. 5. 인삼투여로 알콜유발성 운동실조와 기억의 습득 및 회복의 저해가 보호되었다.

• 대한기계학회논문집
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• 제11권6호
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• pp.1005-1013
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• 1987

For the factory automation and unmanned machine operation, it is very important to manufacture highly reliable and efficient chip breakers for optimal chip control. In this research, using the CALMA CAD/CAM SYSTEM, the manufacturing process of 3-dimensional chip breakers is established. Using the results of the cutting test of the selected chip breakers with double-step grooves, the chip breaking mechanism is schematically analysed. An expression for the chip breaking relation is derived which considers chip material behavior following LUDWIK's stress-strain curve, chip breaking criterion and the shape of chip breakers. This contains the thickness of chip, the radius of chip curl, and the mechanical properties of chip materials. It is found that the expression agrees very closely with the experimental results.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.40-43
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• 2004

A new design method for prestressed concrete girder is proposed in this study, which steps for manufacturing are; (1) the bottom part of concrete girder is placed and pretensioned by the first post-tensioning performed on the tendons located in the bottom part of concrete girder, and (2) the next step which consists of concrete placing and post-tensioning operation is followed by the previous step if required. This indicates that sufficient compressive stress can be effectively introduced at the bottom face in stepwise manner, when compared to conventional PSC girder. Two specimens are prepared and tested to investigate the short-term behavior of the PSC girders manufactured by the proposed method. Section Analysis results exhibit good agreements with the test results in terms of strain distribution across the girder section. In addition, flexural strength obtained from the tests is found to be similar to the expected based on Code(Korea). These demonstrate that the method proposed in this study is applicable to the design of PSC girders.

• Structural Engineering and Mechanics
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• 제5권3호
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• pp.221-237
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• 1997

This paper presents a new uniaxial material model for rate-sensitive analysis addressing both the transient and steady-state responses. The new model adopts visco-plastic theory for the rate-sensitive response, and employs a three-parameter representation of the overstress as a function of the strain-rate. The third parameter is introduced in the new model to control its transient response characteristics, and to provide flexibility in fitting test data on the variation of overstress with strain-rate. Since the governing visco-plastic differential equation cannot be integrated analytically due to its inherent nonlinearity, a new single-step numerical integration procedure is proposed, which leads to high levels of accuracy almost independent of the size of the integration time-step. The new model is implemented within the nonlinear analysis program ADAPTIC, which is used to provide several verification examples and comparison with other experimental and numerical results. The companion paper extends the three-parameter model to trilinear static stress-strain relationships for steel and concrete, and presents application examples of the proposed models.

• 지역사회간호학회지
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• 제33권4호
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• pp.446-455
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• 2022

Purpose: This study investigated the mediating effects of acceptance action on the relationship between diabetes distress and self-stigma in older adults with diabetes. Methods: A descriptive research approach was adopted using 187 patients diagnosed with diabetes mellitus by an endocrinology doctor. The data were collected from 26 to 31 March, 2020 and were analyzed using descriptive statistics, t-test, one-way ANOVA, Pearson's correlation coefficient analysis, and hierarchical multiple regression. Results: The mean scores for diabetes distress, self-stigma, and acceptance action were 2.98±0.64, 2.54±0.74, and 4.16±0.35, respectively. Acceptance action partially mediated the relationship between diabetes distress and self-stigma (z=1.98, p=.024), with an explanatory power of 51.0%. Conclusion: To reduce diabetes self-stigma among old adults in diabetes distress situations, it is necessary to improve their acceptance action and develop step-by-step differentiated acceptance action enhancement programs through multidisciplinary collaborations.