• Steel and Composite Structures
• /
• 제34권6호
• /
• pp.877-889
• /
• 2020

This work features the outcomes of an empirical investigation into the characteristics of steel reinforced grout (SRG) composite - concrete interfaces. The parameters varied were loading rate, densities of steel fibres and types of load displacement responses or measurements (slip and machine grips). The following observations and results were derived from standard single-lap shear tests. Interfacial debonding of SRG - concrete joints is a function of both fracture of matrix along the bond interface and slippage of fibre. A change in the loading rate results in a variation in peak load (P_max) and the correlative stress (σ_max), slip and machine grips readings at measured peak load. Further analysis of load responses revealed that the behaviour of load responses is shaped by loading rate, fibre density as well as load response measurement variable. Notably, the out-of-plane displacement at peak load increased with increments in load rates and were independent of specimen fibre densities.

• 한국유체기계학회 논문집
• /
• 제9권4호
• /
• pp.36-42
• /
• 2006

In the present work, characteristics of the flow in the cage of a steam turbine bypass control valve for thermal power plant are investigated. Experimental measurement for wall static pressure has been carried out to validate numerical solutions. And, the flowfield is analyzed by solving steady three-dimensional Reynolds-averaged Navier-Stokes equations. Shear stress transport (SST) model is used as turbulence closure. The effects of the flow area between stages of the cage on the pressure drop are also found.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 봄 학술발표회 논문집
• /
• pp.549-556
• /
• 2002

Geotextile tubes hydraulically or mechanically filled with dredged materials have been applied in hydraulic and coastal engineering in recent years(shore protection structure, detached breakwater, groins and jetty). It can also be used to isolate contaminated material from harbor, detention basin dredging, and to use this unit as dikes for reclamation work. Recently, new preliminary design criteria supported by model and prototype tests, and some stability analysis calculations have been studied. The stability analysis of geotextile tube is composed geotechnical and hydrodynamic analysis. The stability check points are sliding failure, overturning, bearing capacity failure against the wave attack. In this paper presented the construction procedure and in-situ measurement(properties of filling material, effective height variation, stress variation at geotextile tube bottom) of geotextile tube at Young-Jin Bay and stability analysis by theoretical method and hydraulic model tests

• 한국안전학회지
• /
• 제35권5호
• /
• pp.1-8
• /
• 2020

Mobile elevating work platforms (MEWPs) consist of a work platform, extending structure, and chassis, and are used to move persons to working positions. MEWPs are useful but are composed of pieces of equipment, and accidents do occur owing to equipment defects. Among these defects, accidents caused by the fracture of bolts fixed to the extension structure and swing system are increasing. This paper presents a failure analysis of the fixing bolts of MEWP. Standard procedure for failure analysis was employed in this investigation. Visual inspection, chemical analysis, tensile strength measurement, microstructural characterization, fractography analysis by Optical Microscope(OM) and Scanning Electron Microscopy(SEM), and finite element analysis (FEA) were used to analyze the failure of the fixing bolts. Using this failure analysis approach, we found the root cause of failure and proposed a means for solving this type of failure in the future. First, the chemical composition of the fixing bolt is obtained by a spectroscopy chemical analysis method, which determined that the chemical composition matched the required standard. The tensile test showed that the tensile and yield strengths were within the required capacity. The stress analysis was carried out at five different boom angles, and it was determined that the fixing bolt of MEWP can withstand the loads at all the boom angles. The outcomes of the fatigue analysis revealed that the fixing bolt fails before reaching the design requirements. The results of the fatigue analysis showed primarily that the failure of the fixing bolt was due to fatigue. A visual inspection of the fractured section of the fixing bolt also confirmed the fatigue failure. We propose a method to prevent failure of the fixing bolt of the MEWP from four different standpoints: the manufacturer, safety certification authority, safety inspection agency, and owner.

• 가정과삶의질연구
• /
• 제4권1호
• /
• pp.15-31
• /
• 1986

The purpose of this study is to investigate the relationship between the level of stress recognition of urban housewife and the method of coping, and to explore bow these factors are influenced by socio-demographic variables such as the age of housewife, level of education, status of employment, number of children, durations of marriage, types of family, religion and socio-economic status. The research was conducted on 431 housewives in Seoul in August, 1985. As for the measurement of the instrument, 48 item questionnaire made by investigator was used. The questionnaire was based upon modified and upplemented Holme & Rahe's SRRS and Bell's 18-item Questionnaire to be appropriate to Korean culture. Data were analyzed by percentage, frequency and mean, and verified significant difference by ANOVA and performed Spearman's correlation coefficient. The results of this study are as follows; 1) There is some similarity in distribution of the level of stress recognition of urban housewife. 2) the level of education and the durations of marriage have influence upon the level of stress recognition of urban housewife. In each area, there are differences among groups : age, level of education, durations of marriage, number of children and types of family in the area of education ; age, status of employment, and durations of marriage in the area of health; level of education, durations of marriage, number of children and socio-economic status in the area of finance; status of employment in the area of household work. 3) There are several methods in the method of coping to stress of housewife and the score of long-term coping method appears higher than that of short-term. 4) The level of education, number of children, religion and socio-economic status were variables to have influence on the method level of education, religion and socio- economic status were variables to have influence and in the long-term coping method level of education, number of children, religion, and socio-economic status were to have influence. 5) There is very low positive correlation between the level of stress recognition of urban housewife and the method of coping to stress( ρ=.10, P<.05). 6)In the relation between several variables in socio-demographic variables and the method to coping to stress, the lower the level of stress recognition there are negative correlation (ρ=-.28, P<.01) between religion and the method of coping and also negative correlation (ρ=-.16, P<.05) between number of children and the method of coping. There are positive correlation between socio-economic status and the method of coping.

• 한국콘텐츠학회논문지
• /
• 제9권12호
• /
• pp.750-758
• /
• 2009

본 연구는 현실요법 집단상담 프로그램이 직장인의 직무스트레스 감소에 미치는 영향을 연구하였다. A 지역의 30-40대 생산직 남성 근로자로, 현재 근무하는 직장에서 2년 이상 근무한 사람을 대상으로 하여 실험집단 10명과 통제집단 10명으로 무작위 배정하였다. 측정도구는 한국인 직무스트레스 측정 검사 단축형으로 한국직무스트레스 학회에서 2년에 걸쳐 개발한 표준 도구를 사용하였다. 수집된 자료를 연구 목적에 맞게 분석하기 위하여 t-검증을 실시하였다. 연구결과 전체적인 직무스트레스 점수는 p<.001 수준에서 통계적으로 유의미한 차이가 있는 것으로 나타났으며, 하위영역에서는 직무요구, 조직체계, 보상부적절은 p<.01 수준에서, 직무자율, 관계갈등, 직무불안정, 직장문화는 p<.05 수준에서 통계적으로 유의미한 차이가 있음이 검증되었다. 이와 같은 연구방법을 통하여 도출된 결과를 토대로 다음과 같은 결론을 얻었다. 현실요법 집단상담 프로그램에 참여한 실험집단은 통제집단보다 직무스트레스가 낮아진다. 즉 현실요법 프로그램이 직장인의 직무스트레스를 감소하는데 효과가 있다.

• 접착 및 계면
• /
• 제11권4호
• /
• pp.149-154
• /
• 2010

단일 탄소섬유/페놀수지 및 탄소나노튜브-페놀수지 복합재료의 계면적 특성을 젖음성과 함께 전기저항 측정 및 미세역학시험법을 사용하여 평가하였다. 순수 페놀수지 및 탄소나노튜브-페놀수지 복합재료의 Broutman시편을 사용한 압축강도는 인장강도와 비교하였다. 탄소나노튜브-페놀수지 복합재료의 접촉저항은 2점 및 4점법에 의한 경사형 시편을 사용하여 측정하였다. 동적접촉각에 의한 표면에너지와 젖음성은 Wilhelmy 플레이트 법으로 측정하였다. 표면에서 탄소나노튜브가 불균일한 미세구조로 형성되므로, 동적접촉각은 90도 이상의 소수성을 나타내었다. 탄소나노튜브-페놀수지 복합재료는 보다 나은 응력전달 효과에 기인하여 순수 페놀수지보다 더 큰 겉보기 강성도를 보여주었다. 단일 탄소섬유와 탄소나노튜브-페놀수지 복합재료간의 접착일, $W_a$은 탄소나노튜브 첨가로 인한 점도 증가 때문에, 순수 페놀수지 보다 더 크게 나타났다. 이는 마이크로 풀 아웃 시험에서 단일 탄소섬유의 미세파손 형태와 일치함을 보여 주었다.

• 성인간호학회지
• /
• 제13권4호
• /
• pp.560-570
• /
• 2001

Purpose: The purpose of this study is to identify factors of the causal attribution of cancer and to determine related variables. Method: Subjects were one hundred and thirty three cancer patients. The tool of the perceived causal attribution used was developed by authors and basically founded on Kim's work(1993). The SAS program was used to analyze the data along with descriptive statistics, t-test, ANOVA, Duncan's Multiple range test, and Principal component analysis and varimax rotation. Results: 1) The perceived causal attribution measurement revealed four factors; overload, destiny, stress, and constitution. The total percentage of variance explained by the four factors was 44.3%. 2) The scores of destiny on women, having religion, unemployed, lower level of education, no spouse, groups of uterine cervix and lung cancer, not receiving an operation and receiving radiation were significantly higher than those other groups. 3) The scores of stress on women, having religion, and not having a job were significantly higher than those on men, without religion, and having a job. 4) The scores of constitution on those in their forties, women, not receiving an operation and receiving radiation were significantly higher than for those in their sixties, men, receiving operation and not receiving radiation. There was no significant difference in the factor scores of overload by any variables. Conclusion: Factors of the perceived causal attribution of cancer among Korean cancer patients were overload, destiny, stress, and constitution. The scores of each factor the perceived causal attribution was significantly different by general and disease related characteristics.

• Molecular & Cellular Toxicology
• /
• 제4권4호
• /
• pp.360-365
• /
• 2008

In the last several years, studies on the association of oxidative stress damage with exposure in the work place have been conducted. Xenobiotics create an imbalance of the homeostasis between oxidant molecules and antioxidant defense. By monitoring oxidative stress biomarkers, information was obtained on damages induced by oxidative stress and the toxicity of xenobiotics. In the present study, a Job Exposure Matrix (JEM) was constructed using the data from the Working Environment Measurement (WEM) of painters in the shipyard industry from the past 3 years to assess the exposure status. Additionally, by measuring the concentration of urinary malondialdehyde (MDA), the effect of lipid peroxidation was examined. The subjects consisted of 68 workers who were exposed to mixed organic solvents in the painting process and 25 non-exposure controls. The exposure indices of the exposure groups were significantly different (sprayer: 0.83, touchup: 0.54, assistant: 0.13, P<0.05). The urinary MDA concentration of the exposure group was 48.60${\pm}$ 39.23 ${\mu}mol$/mol creatinine, which was significantly higher than 18.03${\pm}$16.33 ${\mu}mol$/mol creatinine of the control group (P<0.05). From the multiple regression analysis of urinary MDA, the regression coefficient for exposure grade was statistically significant. In future studies, evaluation of the antioxidant levels of subjects should be performed simultaneously with quantitative exposure measurements.

• 지질공학
• /
• 제5권3호
• /
• pp.237-274
• /
• 1995

P파의 속도측정을 이용하여 암석의 공학적 이방성을 추구하는 기법의 개선방안이 연구되었다. 대상시료는, 다른 지질공학적 자료들이 많이 축적되어 있는 영국의 Carnmrnllis 화강암 지역의 현재 강행중인 채석장에서 선택하였다. 곡면을 가지는 시편에서의 측정기법 및 천연꿀 성분의 결합재 사용, 오산화인($P_2O_5$)을 사용한 암석시료 건조법 등의 개선 방안이 본 실험에서 시도되었다. 실험결과, 2차원 평면상에서의 P파 속도의이방성이 0-4.68(%)까지의 값을 보였다. 속도최대치는 현지주응력 방향에 평행한 방향에서 측정되었다. 본 실험의 결과는 암석의 공학적 이방성을 측정하는데 있어 P파 속도치가 유용하게 쓰일 수 있음을 보여주면, 본 실험에서 시도된 개선방안들은 국내의 암석을 대상으로 한 실험에 적용될 수 있다.