• 대한치과보철학회지
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• 제38권5호
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• pp.675-694
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• 2000

The purpose of this study was to investigate the displacement of and the stress distribution on the prosthesis, abutment, and its supporting tissues under functional load, and the effect of alteration in root length of 2nd abutment. The 3-dimensional finite element method was used and the finite element models were prepared in which the abutments of left mandibular 5 unit axed partial denture were canine, the 1st pre-molar and the 2nd molar, and the root lengths of canines were as follows. Model I : Root length of canine was 2mm longer than the 1st premolar Model II : Root length of canine was 2mm shorter than the 1st premolar Static compressive force of 300N was applied to connector between 2nd premolar & 1st molar, and then von Mises stress, displacement and reaction force were obtained. The results were as follows : 1. In fixed partial denture, prosthesis under load on pontic was rotated around mesio-distal long axis of it from longual side to buccal, and simultaneously bended in buccal and gingival direction with mesial end deformed in gingival direction and distolingual end in occlusal. 2. Clinical crowns of abutments were bended in the same directions with those in which prosthesis deforms. Due to that, roots of anterior abutments were twisted in counterclockwise with concentration of shear stress on distal or distobuccal sides of their cervices, and that of posterior was in clockwise with concentration of shear stress on mesiobuccal side of it in the same level with anterior abutments. 3. In case that root length of the 2nd abutment was longer than that of the 1st abutment, its displacement and reaction force which means the force tooth exerts on the surrounding periodontal tissues were smaller but shear stress on itself was larger than in the case root length of 2nd abutment was shorter.

• BMB Reports
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• 제34권6호
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• pp.544-550
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• 2001

In pre-transplant total-body irradiation (TBI), the lung is a critical dose-limiting organ. Also, the possible role of oxidative stress was suggested in the development of TBI-induced lung damage. This study explores the association between TBI-induced oxidative stress and the induction of lung pathogenesis by investigating TBI-induced oxidative stress in the lungs of male C57BL/6 mice after a single dose of 10 Gy TBI. We showed significant increases of reactive oxygen species (ROS) formation and lipid peroxidation, and also a depletion and oxidation of glutathione after TBI. There is evidence that pretreatment with 1,10-phenanthroline (o-phen) significantly reduces oxidative stress in the lung. This indicates that the TBI-induced ROS generation involves a metal-catalyzed Fenton-type reaction. A pretreatment of buthionine sulfoximine (BSO) augmented the glutathione depletion and oxidation, but had no effect on the ROS formation and lipid peroxidation up to 6 h after TBI. Histopathological features that are consistent with pneumonitis were observed in the BSO pretreated-mice 1 week after irradiation. The results suggest that TBI-induced oxidative stress in the lung involves a generation of ROS through a Fenton-type reaction. Also, glutathione plays an important inhibitory role in the radiation-induced lung pathogenesis by participating in the self-amplifying cascade subsequent to the ROS generation by irradiation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.71-76
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• 1994

Recently, constructions of huge reinforced concrete structures such as nuclear power stations have been increased. When massive concrete is placed, cracking due to the hydration heat of cement is recognized as a major problem. The development of thermal stress is influenced by the structure shape and the constraint conditions, and cracks usually occure from tensile stresses which developed due to temperature drop. In this study a protocol specimen is made to examine the distribution of temperature and thermal stress of reaction wall of Daewoo Institute Construction Technology. The size of the specimen is made by considering minimum size of real structure. In this study, concrete strain gauge, concrete stress gauge, concrete non-stress gauge, and thermocouples, are instrumented to measure thermal stress in massive concrete structure. A new measuring technique is proposed to calculate thermal stress.

• Journal of Animal Science and Technology
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• 제65권4호
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• pp.683-697
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• 2023

The threat posed by increased surface temperatures worldwide has attracted the attention of researchers to the reaction of animals to heat stress. Spermatogenesis in animals such as stallions is a temperature-dependent process, ideally occurring at temperatures slightly below the core body temperature. Thus, proper thermoregulation is essential, especially because stallion spermatogenesis and the resulting spermatozoa are negatively affected by increased testicular temperature. Consequently, the failure of thermoregulation resulting in heat stress may diminish sperm quality and increase the likelihood of stallion infertility. In this review, we emphasize upon the impact of heat stress on spermatogenesis and the somatic and germ cells and describe the subsequent testicular alterations. In addition, we explore the functions and molecular responses of heat shock proteins, including HSP60, HSP70, HSP90, and HSP105, in heat-induced stress conditions. Finally, we discuss the use of various therapies to alleviate heat stress-induced reproductive harm by modulating distinct signaling pathways.

• 한국자기학회지
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• 제11권5호
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• pp.226-231
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• 2001

Mn-Zn 페라이트 단결정과 ZnO가 6 mol% 첨가된 SiO$_2$-PbO 다성분계 유리를 700, 800, 900, 1000 $^{\circ}C$에서 열처리시킨 후 계면반응과 자기적 특성 변화를 분석하였다. 계면반응분석 결과, 계면에 2차상은 생성되지 않았으며, 계면의 페라이트 부위에 Zn 농도가 증가하였으며 반대로 Mn 농도는 감소하였다. 열처리 온도가 증가함에 따라 접합시편의 초기 투자율 값이 떨어져, 주파수 100 KHz 에서의 700 $^{\circ}C$ 열처리 시편의 초기투자율은 1766이었으나 1000 $^{\circ}C$에서는 907로 감소하였다. 이러한 초기투자율의 감소는, 계면반응 시 페라이트의 용해 및 성분 원소들의 확산으로 인한 자성 소실부위 발생 및 계면의 페라이트 부위에 생성된 Zn농도 증가 층과의 열팽창계수 타이에 의한 잔류응력 발생에 의한 것으로 판단되었다.

• 아동학회지
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• 제32권5호
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• pp.13-28
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• 2011

This study explored the relationship between parental reaction to children's negative emotions, child's self-regulation and stress-coping behaviors. This study also examined the mediating effect of a child's self-regulation between parental reactions to children's negative emotions and a child's stress-coping behaviors. The sample included 407 elementary school 5th-6th grades and their parents (comprising 407 couples) in Seoul. The research results are summarized as follows. First, parental reactions to children's negative emotions were significantly related to the child's self-regulation and stress-coping behaviors. Secondly, it was also found that parental reactions to children's negative emotion were both partially and indirectly related to a child's stress-coping behaviors through the child's use of self-regulation.

• Journal of Ginseng Research
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• 제35권1호
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• pp.111-123
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• 2011

To investigate the effects of repeated immobilization-stress challenge on the the hypothalamic-pituitary-adrenal axis, the genomic transcriptome in the adrenal cortex of immobilization-stressed mouse was analyzed by using a cDNA microarray. Mice were subjected to immobilization stress for 2 h per day for 5 consecutive d. With a 4.0-fold cutoff of arbitrary criteria, the expression levels of 168 out of 41,174 genes were significantly modulated in the adrenal cortex by stress when comparing the control and experimental groups. These genes were related to apoptosis, cell cycle, immune response, inflammatory responses, and signal transduction, and thus may be used as potential targets for the development of therapeutics for chronic stress or depression. Six significant genes among these were selected for real time polymerase chain reaction analysis to confirm the change of their expression levels. The gene for phospho 1 was also further investigated because its expression showed the greatest fold-change.

• 전기학회논문지
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• 제68권1호
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• pp.52-60
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• 2019

In this paper, four types of insulation coils were fabricated by adding various kinds of glycols to improve the flexibility and adhesion of insulating coils in varnish dispersed with PAI / Nano Silica_15wt%. The applied voltage and frequency were 1.5 kV / 20 kHz for accelerated life evaluation. Through the 6th temperature stress level, the cause of the insulation breakdown of the coil was ignored and only the breakdown time was measured. The Arrhenius model was chosen based on the theoretical relationship between chemical reaction rate and temperature for estimating the insulation life of the coil due to accelerated thermal stress. Three types of distributions (Weibull, Lognormal, Exponential) were selected as the relationship between thermal stress model and distribution. The average insulation lifetime was estimated under the temperature stress of four types of insulation coils through the relationship between one kind of model and three kinds of distributions.

• 한국정보전자통신기술학회논문지
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• 제14권3호
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• pp.215-222
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• 2021

인간과 컴퓨터의 상호 작용 (Human Computer Interface) 기술의 중요성이 더욱 커지고 있으며 HCI에 대한 연구가 진행됨에 따라 사용자의 직접적인 입력에 의한 컴퓨터 반응이 아닌 감정 추론 혹은 사용자 의도에 따른 컴퓨터 반응에 대한 연구가 증가되고 있다. 스트레스는 현대 인간 문명사회에서의 피할 수 없는 결과이며 복잡한 현상을 나타내며 통제 유무에 따라 인간의 활동능력은 심각한 변화를 받을 수 있다. 본 논문에서는 인간과 컴퓨터의 상호 작용의 일환으로 스트레스를 통해 증가된 심박변이도 (HRV)와 가속도 맥파(APG)를 측정한 후 스트레스를 완화시키기 위한 방안으로 음악을 이용한 지능형 감성 추천시스템을 제안하고자 한다. 사용자의 생체정보 즉, 스트레스 지수를 획득 및 인식하여 신뢰성 있는 데이터를 추출하고자 차분진화 알고리즘을 사용하였으며 이렇게 획득된 스트레스 지수를 단계별에 따라 시멘틱 웹 (Semantic Web)을 통해 감성추론을 하였다. 또한 스트레스 지수와 감성의 변화에 매칭 되는 음악 리스트를 검색 및 추천함으로써 사용자의 생체정보에 맞는 감성 추천시스템을 애플리케이션으로 구현하였다.

• 한국융합학회논문지
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• 제13권4호
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• pp.531-540
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• 2022

본 연구는 요양시설 종사자의 코로나 19 대응 전·후 직종별 스트레스 차이를 알아보고자 시도된 서술적 조사연구이다. 본 연구에서는 2021년 3월 22일에서 4월 25일까지 충청남도와 경기도 지역의 요양시설 종사자들에게 설문조사를 시행하였다. 총 220부의 설문지 중 206부의 설문지가 수거되었으며 자료는 t-test, One way ANOVA, chi-square test 등을 통해 분석되었다. 연구결과에서 요양시설 종사자의 코로나 19 대응 전·후 직무 스트레스 하부영역 차이를 보면 간호사는 직무요구(t=-3.90, p<.001), 직무불안정(t=-3.30, p=.002)에서 간호조무사는 직무요구(t=-2.45, p=.018), 요양보호사는 직무자율(t=-3.34, p=.001)에서 유의한 차이를 나타냈다. 따라서 코로나 19 시기에 요양시설 종사자의 직종별 직무 스트레스를 효과적으로 해결하기 위해서는 직종에 따른 스트레스 완화 프로그램을 알맞게 제공해야 한다.