• 한국자동차공학회논문집
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• 제16권5호
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• pp.1-7
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• 2008

A study of new materials that are light-weight, high in strength has become vital to the machinery of auto industries. But then, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress. And Influence of corrosive condition for corrosion fatigue crack was investigated, after immersing in 3.5%NaCl, $10%HNO_3$+3.5%HF, $6%FeCl_3$. The immersion period was performed for 365days. The compressive residual stress was imposed on the surface according to each shot velocity based on shot peening, which is the method of improving fatigue life and strength. Fatigue life shows more improvement in the shot peened material than in the un peened material in corrosion conditions. The threshold stress intensity factor range was decreased in corrosion environments over ambient. Compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation. The fatigue crack growth rate of the Shot-peened material was lower than that of the un peened material. Also m, fatigue crack growth exponent and number of cycle of the shot peened material was higher than that of the un peened material. That is concluded from effect of da/dN.

• 산업융합연구
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• 제3권2호
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• pp.73-84
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• 2005

Musculoskeletal Disorders are usually caused or aggravated by poor work processes and unsuitable working conditions - that involve repetitive or forceful movements or the maintenance of constrained or awkward postures. The condition is characterized by discomfort and persistent pain. Case and Demographic Characteristics for Work-related Injuries and Illnesses Involving Days Away From Work, 2003. U.S" was examined. Causes of musculoskeletal disorders for assembly line workers were carpal tunnel syndrome(CTS), tendonitis, low back pain, and occupational stress. Recommendations of improvement for productivity are redesign of working conditions, exercise, prevent of musculoskeletal disorders and avoiding stress.

• 대한감각통합치료학회지
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• 제2권1호
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• pp.33-42
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• 2004

Objective : To evaluate the sensory processing ability in relation to parenting stress and find the sensory modulation areas affecting the parenting stress in disabled children Methods : Parents of 124 children with disabilities between 3 to 7 years receiving occupational therapy in Seoul and Gyeonggi-do made out the questionnaire and in items of questionnaire, Short Sensory Profile and Parenting Stress Index of short form was included. Results : Among general information, parenting stress of parents had significant correlation with the degree of disability and correlation with the lower level 2 of Parenting Stress Index. The more sensory processing disability was increased, the more parenting stress was increased. Parenting stress showed the significant correlation with movement sensitivity area and under-responsiveness/behaivor area seeking specific stimulation among sensory processing areas and had significant correlation with tactile sensitivity and auditory filtering. Sensory processing areas which affect the most the Parenting Stress were movement sensitivity and under-responsiveness/behaivor area seeking the specific behavior among sensory control disabilities. Conclusion : The parenting stress of parents with the disabled children had the correlation with sensory processing ability. The difficulty of sensory processing increased the parenting stress. Hence, in order to improve children's sensory processing ability, the appropriately coping program should be developed and the appropriate intervention for improvement of sensory processing ability of children will be necessary.

• 한국간호교육학회지
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• 제20권1호
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• pp.47-59
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• 2014

Purpose: The purpose of this study was to review articles and theses on Korean nursing students' stress, identifying overall research trends regarding such stress and suggesting strategies for stress management and nursing education system. Methods: The subjects for this study were 31 articles selected from three databases according to specific inclusion criteria. Results: Twenty-seven articles described survey research and four articles reported on experiments. Twenty-two studies related to stress from clinical practice among nursing students. Thirty-one articles reported on 40 regions and 44 colleges. Seventeen types of tools were used to measure nursing students' stress. The reported reliability of tools ranged from .76 to .96, and the mean score for nursing students' stress fell between 1.98 and 3.95. Conclusion: The findings from this review article indicate that nursing students exhibit different levels of stress as a result of school. Thus, they must learn to cope with stress to support their physical and psychological health. Moreover, finding ways to help student nurses handle job-related stress will require research related to the overall school, the curriculum, learning, and the life of nursing students, as well as stress intervention.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.348-352
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• 2004

Recently the steel parts used for automiles and trains are required to be used under higher stress than ever before in need of the weight down. However, threr are a lot of problems with developing such of fatigue strength and fatigue life are mainly focused on by adopting residual stress. And got the following characteristics from crack growth test carried out stress ratio. Fatigue life shows more improvement in the Un-peening material. And Compressive residual stress of surface on the Shot-peening processed operate resistance force of fatigue. So we cam obtain fallowings. (1) The fatigue crack growth rate on stage II is conspicuous with the size of compressive residual stress and is dependent of Paris equation. (2) Although the maximum compressive residual stress is deeply and widely formed from surface, fatigue life does not improve than when maximum compressive residual stress is formed in surface. (3) The threshold stress intensity factor range is increased with increasing compressive residual stress.

• 한국지반환경공학회 논문집
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• 제21권9호
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• pp.15-24
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• 2020

본 연구에서는 저유동성 몰탈 주입공법의 개량체에 관한 응력분담비를 복합지반법, 지반아칭이론, 소성각법 및 2차원과 3차원 수치해석, 3차원 모형실험을 통해 평가하였다. 복합지반법으로 계산된 응력분담비는 89.3, 3차원 지반아칭이론을 적용할 경우 3.75~59.0, 3차원 소성각법의 경우 82.8로 이론별 응력분담비의 차이가 나타났다. 2차원 수치해석 결과 응력분담비는 63.0~77.0으로 개량율이 증가할수록 증가하는 것으로 나타났고, 3차원 수치해석 결과 50.0~56.0으로 2차원 해석 결과 대비 작게 예측되었다. 대형 삼축압축셀을 이용한 특수 모형 실험의 경우 하중단계별 응력분담비는 53.0~60.0으로 나타났고, 실험으로 평가한 응력분담비는 2차원과 3차원 수치해석적 예측치 내에서 측정되었다. 본 연구에서는 저유동성 몰탈 주입 공법의 개량체에 대하여 해석 및 실험값을 바탕으로 개량율에 따른 응력분담비에 대한 예측식을 제안하였다.

• 한국강구조학회 논문집
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• 제11권3호통권40호
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• pp.319-327
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• 1999

본 연구는 필렛용접 이음으로 된 종리브 십자 시험체를 대상으로 용접토우의 후처리에 의한 피로강도 향상의 메커니즘을 밝히고, 적절한 후처리법을 제안하고자 한다. 인장피로시험 결과, 용접 그대로의 시험체 보다는 후처리된 시험체들에서 피로강도 향상이 보였다. 특히, 피로균열 발생수명 $N_c$는 해머피닝(Hammer-Peening)후 그라인더 처리를 한 시험체에서, 그리고 피로균열 진전수명 $N_p$는 해머피닝 시험체 들에서 각각 증가현상을 보였다. 여기서, $N_c$는 용접토우의 기하학적 형상, 즉 응력집중의 완화때문에, 또한 $N_p$는 해머피닝에 의해 표면에 도입된 큰 압축잔류응력이 피로균열의 진전을 억제하고 있기 때문이라고 생각된다.

• Geomechanics and Engineering
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• 제20권1호
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• pp.75-86
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• 2020

This study aims to simulate the stabilization process of fibrous peat samples using end-bearing Cement Deep Mixing (CDM) columns by three area improvement ratios of 13.1% (TS-2), 19.6% (TS-3) and 26.2% (TS-3). It also focuses on the determination of approximate stress distribution between CDM columns and untreated fibrous peat soil. First, fibrous peat samples were mechanically stabilized using CDM columns of different area improvement ratio. Further, the ultimate bearing capacity of a rectangular foundation rested on the stabilized peat was calculated in stress-controlled condition. Then, this process was simulated via a FEM-based model using Plaxis 3-D foundation and the numerical modelling results were compared with experimental findings. In the numerical modelling stage, the behaviour of fibrous peat was simulated based on hardening soil (HS) model and Mohr-Coulomb (MC) model, while embedded pile element was utilized for CDM columns. The results indicated that in case of untreated peat HS model could predict the behaviour of fibrous peat better than MC model. The comparison between experimental and numerical investigations showed that the stress distribution between soil (S) and CDM columns (C) were 81%C-19%S (TS-2), 83%C-17%S (TS-3) and 89%C-11%S (TS-4), respectively. This implies that when the area improvement ratio is increased, the share of the CDM columns from final load was increased. Finally, the calculated bearing capacity factors were compared with results on the account of empirical design methods.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.717-724
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• 2003

Although sand compaction pile is applied considerably for increase of hearing capacity in domestic, it is getting more necessary to develope the alternative materials because of exhaustion and increase of unit cost of sand. In this study, stress concentration ratio between crushed-stone pile and soft ground was measured and, a displacement ratio 30, 40 and 50%, variation of stress concentration ratio was analyzed. As an increase displacement ratio, the stress concentration effect of crushed-stone compaction pile doesn't increase proportionally and effect of ground improvement in case of ground was good at displacement ratio 30% or 40%. The stress concentration ratio of crushed-stone compaction pile in group piles is 1.5 times that of crushed-stone compaction pile in single pile.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.966-973
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• 2005

The stress concentration ratio in accordance with area replacement ratios were considered as core elements of design. However, the stress concentration ratio will be vary depends on progress of consolidation in clay ground. And, since it is not sure to know the affecting factors accurately, the value is decided based on field experiences. To use SCP method more effective and correspond to soil improvement, the decision on proper area replacement ratio through the exact stress concentration ratio is very important. Accordingly, a numerical analysis on influence of various factors that needed to make rational designing guide for decision of proper area replacement ratio to stress concentration ratio was executed in this study.