• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.23-31
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• 2024

Ratcheting is the cyclic buildup of inelastic strain on a structure resulting from a combination of primary and secondary cyclic stress. It can lead to excessive plastic deformation, incremental collapse, or fatigue. Ratcheting has been numerically investigated on a cantilever beam, considering the current study's primary and secondary bending loads. In addition, the effect of input frequency on the onset of ratcheting has been investigated. The non-linear dynamic elastic-plastic approach has been utilized. Analogous to Yamashita's bending-bending ratchet diagram, a non-dimensional ratchet diagram with a frequency effect is proposed. The result presents that the secondary stress values fall sequentially with the increase of primary stress values. Moreover, a displacement amplification factor graph is also established to explain the effect of frequency on ratchet occurrence conditions. In terms of frequency effect, it has been observed that the lower frequency (0.25 times the natural frequency) was more detrimental for ratchet occurrence conditions than the higher frequency (2 times the natural frequency) due to the effect of dynamic displacement. Finally, the effect of material modeling of ratcheting behavior on a beam is shown using different hardening coefficients of kinematic hardening material modeling.

• Journal of Korean society of Dental Hygiene
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• v.4 no.2
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• pp.209-223
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• 2004

The purpose of this study is to help dental hygienist's efficient work and 10 use this data as basic material for quality improvement of medical treatment by identify and analyze dental hygienist's job-stress and self-conception. This data was surveyed by 197 dental hygienists who working at Dental Clinic, Dentist's office, and Dental Dept on the General hospital in Daegu area. The result as follow. 1. General characters of dental hygienist who participated this survey was mostly less than 25years old and works in the Dentist's office. 2. The dental hygienist's job stress average 259, self-conception was average 3.06. 3. A stress degree by the primary factors appeared that the stress related to Role-conflict was the hygienist. On the other hand, stress related to employees was the lowest. 4. Concerning the stress of respondent's expert knowledge or technique, there exist statistically significant relations in age(p=0.000). Total period of work(p=0.000)), marriage(yes or no)(p=0.012), number of job movement(p=0.024). 5. Concerning the mutual analyze between stress by the primary factors and self-conception, there exist statistically significant relations in stress from expert knowledge or technique(p<0.05, r=0.l53), conflict with patient(p<0.001, r=0.347), conflict between dentist and patient(p<0.05, r=0.159), relationship with employee(p<0.05, r=0.l83). In conclusion, there were significant relations between job-stress and conception. The study of program development for the self-conceit, positive attitude and self-conception are highly required to help dental hygienist's efficient work.

• Journal of Photoscience
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• v.8 no.1
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• pp.13-17
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• 2001

Cucumber leaves subjected to light chilling stress exhibit a preferential inactivation of photosystem(PS) I relative to PSII, resulting in the photoinhibition of photosynthesis. In light chilled cucumber leaves, Cu/Zn-Superoxide dismutase(SOD) is regarded as a primary target of the light chilling stress and its inactivation is closely related to the increased production of reactive oxygen species. In the present study, we further explored that inactivation of PSI in cucumber leaves is not a light chilling specific, but general to various oxidative stresses. Oxidative stress in cucumber leaves was induced by treatment of methylviologen(MV), a producer of reactive oxygen species in chloroplasts. MV treatment decreased the maximal photosynthetic O$_2$ evolution, resulting in the photoinhibition of photosynthesis. The photoinhibition of photosynthesis was attributable to the decline in PSI functionality determined in vivo by monitoring absorption changes around 820 nm. In addition, MV treatment inactivated both antioxidant enzymes Cu-Zn-superoxide dismutase and ascorbate peroxidase known sensitive to reactive oxygen species. From these results, we suggest that chloroplast antioxidant enzymes are the primary targets of photooxidative stress, followed by subsequent inactivation of PSI.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.27-39
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• 1996

A finite element analysis of a trunnion pipe anchor is presented. The structure is analyzed for the case of internal pressure and moment loadings. The stress results are categorized as average and linearly varying(through the thickness) stresses. The resulting stresses are interpreted per Section 111 of the ASME Boiler and Pressure Vessel Code from which the Primary(B$_1$) and Secondary(C$_1$) stress indices for pressure, the Primary(B$_2$) and Secondary(C$_2$) stress indices for moment are developed. Several analysis were peformed on various structural geometries in order to determine empirical relationships for the stress indices as a function of dimensionless ratios.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.631-640
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• 2013

This paper provides a comparison of the J-integral estimation method under combined primary and secondary stress in the R6, RCC-MR A16 code. The comparisons of each code are based on finite element analysis using ABAQUS with regard to the crack shape, crack depth, and magnitude of secondary load. The estimate of the R6 code is conservative near $L_r=1$, and that of the RCC-MR A16 code is conservative near $L_r=0$. As a result, this paper proposes a modified method of J-integral estimation in the R6, RCC_MR A16 code. The J-integral using the modified method corresponds to the finite element analysis result.

• The Korean Journal of Rehabilitation Nursing
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• v.1 no.1
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• pp.1-14
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• 1998

The purpose of this study was to identify the factors affecting family functioning of stroke patients. A descriptive survey research was conducted in which 65 stroke patients and their primary caregivers were conveniently sampled. Data were collected from July to September, 1998 through interviewing using a structured questionnare. The measuring instruments used were Barthel Index by Mahoney and Barthel(15 items), Quality of Relationship Scale by Archbold and Stewart(15 Items), Role Stress of Caregiver Scale by Yang(14 items), Situational Definition Scale by Lee(9 items), Family Hardiness Index by McCubbin, McCubbin. and Thompson(20 items), and Family Adaptability Cohesion Evaluation Scale(FACES-III) by Olson, Portner, and Lavee(20 items). The obtained data were analyzed using percentage, t-test, ANOVA, Duncan test, and Pearson coefficients correlation by SAS/PC program. The results were as follows; 1. Role Stress of Caregiver was not severe and Quality of Relationship was moderate. The level of Situational Definition of primary caregivers was not high but Family Hardiness and Family Functioning were rather high. 2. The following relationships between research variables and demographic characteristics of the primary caregivers of stroke patients were significantly different; occupation of caregiver between Quality of Relationship, occupation of caregiver between Situational Definition, family type between Role Stress, caregiving duration between Family Hardiness, caregiving duration between Family Functioning, and hospitalization days between Family Functioning. 3. The correlations between research variables were as follows; There was positively correlated between patient's ADL and Quality of Relationship. The relationship of the patient's ADL between Role Stress was negatively correlated. Quality of Relationship between Situational Definition, Family Hardiness, and Family Functioning were significantly correlated. The correlation of Situational Definition between Family Hardiness, and Situational Definition between Family Functioning were very high. As a result of these findings, Quality of Relationship, Role Stress, Situational Definition. and Family Hardiness were useful variables for identifying Family Functioning of stroke patients. It is important for the rehabilitation nurse to be knowledgeable about family functioning of stroke patients to promote rehabilitation process.

• Journal of Korean Public Health Nursing
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• v.15 no.1
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• pp.96-110
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• 2001

The purpose of this study was to examine the effect of emotional and informational support intervention on role stress and depression of primary family caregivers caring stroke patients and to develop an effective nursing intervention method for them. This study selected the quasi-experiment, based on pre-test and post-test design of non-equivalent control group as a method of study. This study was conducted with 69 primary family caregivers caring stroke patients hospitalized in K and D hospitals in Daegu from August 20 to October 25, 2000. Out of them, 34 were placed in the experimental group, and 35 in the control group. The emotional and informational intervention program was divided into two aspects-emotional support and informational support- and executed three times, using prepared instruments and a guidebook. The intervention program consisted of the 1st intervention for one or one-half hour, the 2nd intervention for 30 minutes in two or three days after the 1st intervention. and the 3rd intervention for 30minutes in another two or three days after the 2nd intervention. Pre-test was carried out just before the 1st intervention, and the post-test was carried out right after the 3rd intervention, in order to collect data. The measuring instrument of role stress used was one that was modified to the role stress instrument of Yang Young-hee(1992) and the stress instrument of Choi Eun-sook (1992). The reliability was Cronbach's $\alpha=.8271$. The measuring instrument of depression used was one that was developed by Beck(1967) and standardized by Han Heung-moo et al(1986). The reliability was Cronbach's $\alpha=.8693$. Data were analyzed with percentage, mean, standard deviation, $x^2-test$, t-test and Paired t-test by using SPSS 9.0 program. The results of this study are summarized as follows: 1. Role stress score of the experimental group was revealed to be significantly lower than that of the control group 2. Depression score of the experimental group was revealed to be significantly lower than that of the control group Accordingly, the emotional and informational support intervention can be a way to reduce role stress and depression of primary family caregivers caring stroke patients.

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.628-636
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• 2020

The purpose of this study was to investigate how self-help group conducted by 25 dementia safety centers in Seoul correlated the stress and life satisfaction of primary care-givers of dementia patients. At 25 dementia safety centers, self-help groups were identified, and a survey was conducted for the care-givers of dementia patients participating in the self-help groups. SPSS 21.0 program was used for the collected data, and reliability was analyzed for stress level and satisfaction after the program. Multivariance analysis and one-way analysis were performed for the types of self-help groups, the frequency of attendance, and the number of meetings. The result were : first, the total stress felt by participants was close to 4 out of 5, and there was no significant difference in meeting type and attendance frequency, and only in the relationship between stress and the number of self-help groups(p<.05). Second, the satisfaction after self-help meetings was close to 4 out of 5, the meeting type and attendance frequency no significant difference, and only the number of self-help meetings showed a significant difference(p<.05). Third, there was a significant negative correlation in the relationship between stress and program satisfaction. As can be seen from the results, it can be seen that self-help groups have an effect on the stress of primary care-givers and the satisfaction level after meeting.

• Korean Journal of Environmental Agriculture
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• v.12 no.3
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• pp.264-280
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• 1993

The environmental pollutions were a serious problem in Korea recently. So many researcher have studied the effect of environmental pollution on plants and agro-ecosystem, but the basic mechanisms of environmental stresses were various. One of the important mechanisms was oxidative stress caused by active toxic oxygen. The toxic oxygen was generated by several stresses, abnormal temperature, many xenobiotics, air pollutants, water stress, fugal toxin, etc. In the species of toxic oxygen which is primary inducer of oxidative stresses, superoxide, hydrogen peroxide, hydroxyl radical and singlet oxygen were representative species. The scavenging systems were divided into two groups. One was nonenzymatic system and the other enzymatic system. Antioxidants such as glutathione, ascorbic acid, and carotenoid, have the primary function in defense mechanisms. Enzymatic system divided into two groups; First, direct interaction with toxic oxygen(eg. superoxide dismutase). Second, participation in redox reaction to maintain the active antioxidant levels(eg. glutathione reductase, ascorbate peroxidase, etc.).

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.347-348
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• 2005

A proving ring test method equipped with DCPD was developed and applied to detect the crack initiation time in PWR primary water conditions. The specimens were exposed to the PWR primary water environment during one month. The DCPD signals were very clear but the crack initiation was not detected manly because of the low stress condition. To increase the stress condition, Ni plating will be conducted after the straining the specimens.