• 한국안전학회지
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• 제32권4호
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• pp.79-88
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• 2017

The purpose of this study is to analyze the effects of personal, job, and health care characteristics of firefighters on musculoskeletal disorders (MSDs) and job stress. This survey was participated 591 firefighters in jeonnam and Busan city. The survey consisted of 1) personal, job, and health care characteristics measurement, 2) job stress measurement (KOSS, Korean Occupational Stress Scale), 3) musculoskeletal disorders symptoms mesurement. The analysis of the data was using SAS 9.1 Ver. The statistics analysis was performed the frequency, percentage, average, and standard deviation for each survey item. The Chi square analysis was performed to analyzed the effects of personal, job, and health care characteristics on MSDs and job stress. According to the results of the study on musculoskeletal disorders symptoms, 49.6% of the subjects perceived pain related to musculoskeletal diseases. The total score for job stress was 51.6 (SD 12.9), which was the highest 50% when compared to the Korean job stress standard (male). Age, department, work experience, working type, position, and sleeping time were found to affect musculoskeletal disorders and job stress.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.372-377
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• 2002

Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

• International Journal of Korean Welding Society
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• 제2권1호
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• pp.40-44
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• 2002

Residual stress by welding should be reduced because that decreases the reliability on strength of welded structure. The reason is that the total stiffness of structure decreases by non-linear behavior of weldment under external load. The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure for steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. This simulation model should be established on the based of variable and accurate measurement data. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test under variable load was performed and the proper degree of stress relaxation was measured by sectioning technique using strain gauge.

• Journal of Animal Science and Technology
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• 제64권4호
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• pp.621-639
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• 2022

Cortisol and corticosterone, hormones traditionally considered biomarkers of stress, can be measured in fluid biomatrices (e.g., blood, saliva) from live animals to evaluate conditions at sampling time, or in solid biomatrices (e.g., hair, feather) from live or dead animals to obtain information regarding long-term changes. Using these biomarkers to evaluate physiological stress responses in domestic animals may be challenging due to the diverse characteristics of biomatrices for potential measurement. Ideally, a single measurement from the biomatrix should be sufficient for evaluating chronic stress. The availability of appropriate and cost-effective immunoassay methods for detecting the biomarkers should also be considered. This review discusses the strengths and limitations of different biomatrices with regard to ensuring the highest possible reliability for chronic stress evaluation. Overall, solid biomatrices require less frequent sampling than other biomatrices, resulting in greater time- and cost-effectiveness, greater ease of use, and fewer errors. The multiplex immunoassay can be used to analyze interactions and correlations between cortisol and other stress biomarkers in the same biomatrix. In light of the lack of information regarding appropriate biomatrices for measuring chronic stress, this review may help investigators set experimental conditions or design biological research.

• 터널과지하공간
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• 제26권4호
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• pp.304-315
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• 2016

본 연구에서는 포항 도움산 지역 내 시험공 3개소의 심도 75 m~716 m 구간에서 획득된 원위치 암반 초기응력 측정 자료를 바탕으로 포항분지 제3기 지층 내에 형성되어 있는 수평응력 분포 특성을 분석하였다. 수압파쇄법에 의한 대심도 초기응력 측정 결과, 조사 지역의 수평응력 성분 크기는 국내 여러 지역 자료에 대한 선형 회귀분석으로부터 계산된 평균값에 비해 매우 낮은 범위의 값을 나타내었다. 그러나 시추공 스캐닝 조사에서 분포 암종의 낮은 강도 특성에 의해 유발된 다양한 규모의 시추공 파괴 현상들이 다수 확인되었다. 최대 수평응력의 방향성에 대한 보다 정확하고 폭넓은 정보를 도출하기 위해 수압파쇄시험과 시추공 스캐닝 자료에 대한 통합 분석을 추가적으로 수행하였다. 분석 결과, 상부 퇴적암층과 하부 화산암층에서 최대 수평응력 작용 방향은 각각 진북 기준 $80^{\circ}{\sim}100^{\circ}$ (N80E~N80W)와 $120^{\circ}{\sim}140^{\circ}$ (N60W~N40W) 방위각에서 우세한 방향성을 나타내었다. 이러한 연구 결과로부터 심도 증가로 지층이 변화함에 따라 최대 수평응력 방향이 시계 방향으로 회전하는 경향성을 확인할 수 있었다.

• 한국정밀공학회지
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• 제18권6호
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• pp.59-66
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• 2001

Fatigue strength of the welding structure is governed by the residual stress at the weldment toe and static tensile overloads were known as relieving the residual stresses. In this study, static tensile overloads were applied to the welding structures which caused the relief of residual stresses. The amount of residual stress relief was found as proportional to the change of fatigue limit at the given conditions. Based on the fact of the proportionality between the change of fatigue limit and that of residual stress, simple measurement technique is proposed. Modified stress-life curves base on proposed technique gave good agreement with test results.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.30-40
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• 2016

The paper investigates the previous studies about welding residual stresses in nuclear components. First, various residual stress measurement methods are reviewed in applicability. Second a finite element welding residual stress analysis technique, which was developed from the viewpoint of FFS (Fitness-For-Service) assessment, is explained. Third, characteristics of the welding residual stresses on J-groove welds and butt welds were presented via investigating the previous studies. Last, engineering formulae for residual stresses in the FFS assessment codes such as R6 and API 579/ASME FFS-1 Code is summarized.

• 대한기계학회논문집A
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• 제24권8호
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• pp.2059-2064
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• 2000

The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, one of the source of error is due to the misalignment between the drilling hole and strain gage center. This paper presents a finite element analysis of the influence of such misalignment for the uniaxial residual stress field. The stress error increases proportionally to hole eccentricity. The correction equations which easily obtain the residual stress taking account of the hole eccentricity are derived. The stress error due to the hole eccentricity decreases by approximately one percent using this equations.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.423-428
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• 2005

If the load of constructing vehicles during the construction work acts on the road or the ground surface on the soft ground, due to the excess stresses in soils the trafficability of the vehicles influences the constructing efficiency, constructing period and so on. Stress distribution in soils is the very important element to design and to solve the problems of settlement, safety of foundations and trafficability of constructing vehicle in civil engineering. This research represents the comparative estimation of the actual and theoretical measurement on the underground stress of outer layer for each soil after the observation of each top soil layer for its vertical and horizontal stress in (1)homogeneous sand ground (2) weak stratum with the sand soil (3) weak stratum with gravel of the soil model, and it also investigates the effect of subsidence of ground by the repeated load. The underground stress turn out to be different in the value of theoretical and actual measurement after the trial examination of model.

• 한국정밀공학회지
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• 제13권4호
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• pp.53-60
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• 1996

In the conventional linear elasticity, sound speed is determined by only elastic modulus and density of the medium. In actual, however, sound speed depends on the stress and this dependency becomes nonlinear as the stress increases. These phenomena can be introducing nonlinear elastic modulus. In this paper, relationships between nonlinear elastic modulus up to 4th order and the internal status of materials are discussed through computer simulations and experiments. For the measurement of sound speed, a new type of measurement system using ultrasonic wave is proposed on the basis of ultrasonic pulse echo method which has been generally used in nondestructive ultrasonic test equipment. In order to confirm the stress dependency of sound speed, several experiments are carried out for alumina specimen.