• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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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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• v.34 no.6
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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.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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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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• v.65 no.4
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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.

• Journal of the Korean Magnetics Society
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• v.11 no.5
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• pp.226-231
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• 2001

The effect of interface reaction between Mn-Zn ferrite single crystal and 61 SiO$_2$-23Pbo-6ZnO-8Na$_2$O-2K$_2$O (mol%) glass on the magnetic properties of the ferrite was investigated. After the reaction, the hump of Zn concentration appeared at the ferrite adjacent to the interface. The initial permeability of the ferrite bonded with the glass at 700 $^{\circ}C$ was 1766 at 100 KHz and reduced to 907 after reaction at 1000$^{\circ}C$. The permeability degradation with increasing reaction temperature was considered to be attributed not only to the sixe diminution of the ferrite due to the its dissolution into the glass but also to the residual stress due to the difference in expansion coefficient between the ferrite and the diffusion layer-the region of the hump of Zn concentration-adjacent to the interface.

• Korean Journal of Child Studies
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• v.32 no.5
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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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• v.35 no.1
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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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.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.3
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• pp.215-222
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• 2021

As the importance of human-computer interaction (Human Computer Interface) technology grows and research on HCI is progressing, it is inferred about the research emotion inference or the computer reaction according to the user's intention, not the computer reaction by the standard input of the user. Stress is an unavoidable result of modern human civilization, and it is a complex phenomenon, and depending on whether or not there is control, human activity ability can be seriously changed. In this paper, we propose an intelligent emotional recommendation system using music as a way to relieve stress after measuring heart rate variability (HRV) and acceleration photoplethymogram (APG) increased through stress as part of human-computer interaction. The differential evolution algorithm was used to extract reliable data by acquiring and recognizing the user's biometric information, that is, the stress index, and emotional inference was made through the semantic web based on the obtained stress index step by step. In addition, by searching and recommending a music list that matches the stress index and changes in emotion, an emotional recommendation system suitable for the user's biometric information was implemented as an application.

• Journal of the Korea Convergence Society
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• v.13 no.4
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• pp.531-540
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• 2022

This study is a descriptive survey study attempted to find out the difference in stress by occupation before and after responding to COVID-19 among care facility for the elderly. In this study, a survey was conducted on workers in care facility for the elderly in Chungcheongnam-do and Gyeonggi-do from March 22 to April 25, 2021. Of a total of 220 questionnaires, 206 were collected, and the data were analyzed through t-test, one way ANOVA, and chi-square test. According to the research results, the difference in the sub-areas of job stress before and after the COVID-19 response of nursing home workers shows that nurses have job demands(t=-3.90, p<.001), job instablity(t=-3.30, p=.002), the nursing assistant has job demands(t=-2.45, p=.018), nursing care workers have job autonomy(t=-3.34, p=.001) showed a significant difference. Therefore, in order to effectively solve job stress according to the occupation of workers in care facility for the elderly in the COVID-19 era, stress relief programs for each occupation must be customized.