• 한국농공학회지
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• 제17권4호
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• pp.3921-3930
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• 1975

This research was carried out to investigate several mechanical characteristics of pre-stressed steel beams. The configuration of specimens used for this study were as follows; a cover plate having permissible fiber stress of 4,000 kg/$\textrm{cm}^2$ was welded at bottom having the allowable bending stress 2500 kg/$\textrm{cm}^2$ steel beam, the section ratios of pre-stressed steel beam and cover plate were 0.5 and 0.6. Adopted pre-stresses were 0%, 50%, and 100% of an allowable fiber stress of a steel beam. The results obtained from the study may be summarized as follows; 1. The elastic range of a beam was increased by the application of pre-stress to the beam, which leads to a lighter section. 2. The permissible moment capacity of a pre-stressed steel beam was greated than that of a steel beam without pre-stressing. 3. The equivalent allowable stress induced by adopting the different section ratio of pre-stressed beam to cover plate were figured out 4. The optimum value of section ratio of beam and cover plate was 0.3 to 0.4 in case of a 1.5m span composite beam, a combination of an allowable stress 2,500kg/$\textrm{cm}^2$ steel beam and a permissible fiber stress 4,000 kg/$\textrm{cm}^2$ steel cover plate, was used. 5. The magnitude of the pre-stress was desirable to be same as the allowable stress of a steel beam. 6. It was concluded that if the construction techniques in the field are developed and improved, the practicing of pre-stress to the steel structure has a promising future.

• 대한화학회지
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• 제67권6호
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• pp.462-474
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• 2023

본 연구의 목적은 예비 화학교사가 교육실습에서 경험하는 스트레스를 분석하는 것이다. 이를 위해 예비 과학교사 스트레스 검사 도구를 제작하여, 예비 화학교사 19명을 대상으로 교육실습 전 예상한 스트레스와 교육실습에서 경험한 스트레스를 조사하였다. 교육실습 전과 후에 온라인으로 실시한 설문 조사의 결과는 기술 통계를 수행하였고, 예비 화학교사의 스트레스 검사 결과에 대한 해석은 교육실습 과정에서 작성한 티칭포트폴리오와 면담자료를 활용하여 분석되었다. 연구 결과는 다음과 같다. 첫째, 예비 화학교사들은 교육실습 전 다양한 스트레스를 예상하였으나, 교육실습에서 스트레스를 받는 요인의 수와 스트레스를 받은 예비 화학교사의 수가 대체로 적어졌다. 둘째, 예비 화학교사가 교육실습을 경험한 학교급에 따라 교육실습 전 예상한 스트레스와 교육실습에서 경험한 스트레스의 요인과 스트레스의 정도가 다르게 나타났다. 셋째, 예비 화학교사가 교육실습 과정에서 경험한 스트레스는 성별에 따른 차이는 나타나지 않았다.

• 농업과학연구
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• 제45권1호
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• pp.58-65
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• 2018

Meat quality includes technological quality attributes, consumer acceptance, and credence characteristics. In terms of credence characteristics, animal welfare is one of the most interesting topics to both consumers and the livestock industry. Consumers prefer meat produced from livestock that has been raised in low stress and ecofriendly environments. The livestock industry cares about animal welfare to meet the requirements of consumers. Animal welfare is closely associated with the stress and physiological response of livestock to stress. Moreover, stress just before slaughter (i.e., pre-slaughter stress) has negative effects on not only animal welfare but also ultimately on meat quality. It is well-documented that pre-slaughter stress can influence ante- and post-mortem biological changes of the muscles, especially their metabolic properties and metabolites. The metabolic properties and metabolites contents also can modulate the postmortem changes of the muscles. Conversion of muscles to meat during postmortem is a very important process because it determines ultimately the meat quality. Thus, understanding pre-slaughter stress and physiological responses to stress in farm animals is important for animal welfare and meat quality. The purpose of this paper was to examine the concept of stress, physiological responses to stress, measurement of stress, and the relationships between stress indices and meat quality traits.

• 산업식품공학
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• 제13권1호
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• pp.70-73
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• 2009

The yield stress of stirred yogurt was measured by the vane viscometer at different pre-shearing conditions, such as pre-shear speed, pre-shear time, and wait time, and temperature (12-38${^{\circ}C}$). The yield stress ranged from ~17.6 to 10 Pa and from 34.2 to 11.9 Pa, depending on the pre-shearing conditions and temperature, respectively. The preshear speed and the wait time significantly affected the yield stress. The temperature dependence of the yield stress was described by the Eyring's kinetic model. The linear function of the temperature on the yield stress was limited at the 22${^{\circ}C}$, and at the above 22${^{\circ}C}$, the yield stress was maintained to be a constant (~12.5 Pa).

• 동의신경정신과학회지
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• 제20권3호
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• pp.35-47
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• 2009

Objectives : The effects of Pinelliae Rhizoma extract(PRe) were tested for the anti-stress action. Methods : PRe was fed to ICR male mice($20{\pm}2g$) orally with the dose of 100 mg/kg/day for five days. Mice were exposed to sociopsychological stress by restraining and seeing foot shock stressed mice for one hour for five days. Results : PRe administration had the effect of decreasing serum level of lipid peroxidation. The elevated plus-maze test is designed to detect the effect of anxiolytic drugs, and PRe administration group showed a significant increase of latency time. From Microarray, common features between mind-stimulus related genes and body-stimulus related genes were not so abundant When PRe was administered, there were some changes in distributions of mind-stimulus related genes but the distributions were not recovered to normal status. Conclusions : These results suggest that PRe can effectively rid the sociopsychological stress and stress concrened diseases.

• 한국보육지원학회지
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• 제7권4호
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• pp.95-118
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• 2011

본 연구의 목적은 예비유아교사들의 여가활동 실태와 스트레스 수준을 알아봄으로써 예비유아교사의 생활지도를 위한 참고자료를 제공하는 것이다. 본 연구를 위하여 557명의 유아교육과, 아동복지학과 학생들에게 설문조사를 실시하였다. 설문은 인구학적 변인, 여가활동, 스트레스수준으로 구성되었다. 분석은 spss통계 프로그램을 사용하였다. 본 연구의 결과를 통해 예비유아교사들은 여가활동이 제한적이며, 학업수행에 대해 스트레스 수준이 높고, 수입과 지출의 불균형을 경험하고 있는 것을 알 수 있었다. 예비유아교사의 교육에 대한 시사점은 다음과 같다. 첫째, 예비유아교사들의 여가활동을 다양하게 할 수 있도록 지원해주어야 한다. 둘째, 예비유아교사들의 학업 수행을 지원하기 위한 다양한 시도가 필요하다. 셋째, 예비유아교사들의 건강한 생활패턴과 건전한 경제생활을 위한 생활지도가 요구된다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.249-249
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• 2002

• Computers and Concrete
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• 제11권2호
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• pp.169-182
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• 2013

One of the major benefits of the pre-stressed concrete pavements is the omission of tension in concrete that results in a reduction of cracks in the concrete slabs. Therefore, the life of the pavement is increased as the thickness of the slabs is reduced. One of the most important issues in dealing with the prestressed concrete pavement is determination of the magnitude of the pre-stress. Three dimensional finite element analyses are conducted in this research to study the pre-stress under various load (Boeing 777) and thermal gradient combinations. The model was also analyzed under temperature gradients without the presence of traffic loading and the induced stresses were compared with those from theoretical relationships. It was seen that the theoretical relationships result in conservative values for the stress.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.270-274
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• 1996

Until recently pre & post-processing of finite element model has been heavily relied on expensive graphic peripheral devices. But today, with the aid of inexpensive microcomputers, very effective pre & postprocessor graphics has been developed. In this study, Pre & Post processor(MASSPRE, MASSPOST) of prediction analysis of thermal stress in mass concrete structure is developed. The developed pre & post processors are raise to the efficiency in making input data for the main program and analysis of the results produced by the main program. This MASSPOST presents a stress contour graph, volume slice, time-temperature history graph, time-stress history graph, etc.

• Journal of Acupuncture Research
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• 제20권3호
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• pp.177-193
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• 2003

Objective : The present studies investigated the effects of 120Hz high frequency electroacupunctue(EA) on the stress-induced stomach dysfunction in relation to its effect on the level of stress hormone and gastric mucosal damages. The gastric mucosal injury was induced by cold-restraint stress and two acupoints corresponding to Zusanli and Sanyinjiao in man were used. Methods: Cold-restraint stress produced typical gastric lesions in all rats of the stressed groups, but he number of ulcers as well as the mean ulcer diameter were reduced by 120 Hz EA pre-treatment. The cold-restraint stress also induced an increase in catecholamine response involving epinephrine, norepinephrine and dopamine, but an slight decline were observed in EA pre-treated rats compared with cold-restrained rats. Results: The degranulation value of gastric mast cell was significantly higher in cold-restrained rats than in control ones. However, with the significant reduction of degranulation values of gastric mast cells in EA pre-treated rats compared with cold-restrained ones, $PGE_2$ content in the gastric mucosa of EA pre-treated rats was also different from that observed in cold-restrained rats. Cold-restraint stress induced an elevated mRNA expression of pro-inflammatory gene such as cyclooxygenases-2 and tumor necrosis factor(TNF)-${\alpha}$, but these expression were down-regulated in EA pre-treated rats. Immunohistochemecal analysis showed that while the inhibitory-${\kappa}B{\alpha}$ an TNF-${\alpha}$ immunoreaction in the surface epithelium of the stomach tended to increase, both reactions in the EA pre-treated rats showed similar pattern as observed in controls. Conclusions : These results suggest that 120 Hz EA may act as a therapeutical means for gastric mucosal damages through a activation of pituitary adrenal system. it could be concluded that 120 hz high frequency electroacupuncture affords a good protective potential against stress-induce gastrointestinal dysfunction.