• Journal of Mechanical Science and Technology
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• 제18권3호
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• pp.453-459
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• 2004

TiNi/ Al6061 shape memory alloy (SMA) composite was fabricated by hot press method to investigate the microstructure and mechanical properties. Interface bonding between TiNi reinforcement and A1 matrix was observed by using SEM and EDS. Pre-strain was imposed to generate compressive residual stress inside composite. A tensile test for specimen, which under-went pre-strain, was performed at high temperature to evaluate the variation of strength and the effect of pre-strain. It was shown that interfacial reactions occurred at the bonding between matrix and fiber, creating two inter-metallic layers. And yield stress increased with the amount of pre-strain. Acoustic Emission technique was also used to nondestructively clarify the microscopic damage behavior at high temperature and the effect of pre-strain of TiNi/ Al6061 SMA composite.

• Environmental Analysis Health and Toxicology
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• 제18권3호
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• pp.165-174
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• 2003

Cr (Ⅵ) - containing compounds are well-established carcinogens, although the mechanism for chromium - induced carcinogenesis is still not well understood. The reduction of Cr (Ⅵ) to its lower oxidation states, par ticularly Cr (V) and Cr (IV), is an important step for the production of chromium-mediated reactive oxygen species (ROS). The persistent oxidative stress during the reduction process may play a key role in the mechanism of Cr (Ⅵ) -induced carcinogenesis. This paper summarizes recent studies on (1) the reduction of Cr (Ⅵ) to Cr (III) occur by a multiplicity of mechanisms depending on the nature of reducing agents including ascorbate, diol-and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (2) free-radical production with emphasis on hydroxy radical generation via Fenton or Haber-Weiss type reactions; and (3) free radical - induced cellular damage, such at DNA strand breaks, hydroxylation of 2'-deoxyguanosine, and activation of nuclear transcription factor kB.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1992년도 추계학술대회논문집
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• pp.96-103
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• 1992

To get a comfortable sleep, the most improtant thing is how well we do thermorgulate during the rest in bed before sleeping as well as during sleep. In other works, the ambient temperature of the sleeping room is very improtant in the organization of human sleep. In recent years, the effect of ambient temperature on human sleep has been increasingly stueided. These studies were primarily concerned with the relation between thermorgulatory processes and sleep, and more precisely with the findings that various thermoregulatory processes are inactivated or severly curtailed during REM sleep in a number of animals, also that panting and shivering in heat and cold, respectively, cease during REM sleep in cats. Haskel et al. noted that although REM sleep latency was increased at thigh and low temperature. REM sleep was depressed to a greater extent by lower than by higher temperatures whereas the reverse was obseved for SWS. It has also been found that a load omposed upon thermoregulatory mechanisms should markedly affect sleep processes, and that conversely, sleep in conditions of thermic stress should interfere with adequate thermorgulatory reactions. Sleep in an animala under thermic stress is, on the whole, both shorter and less deep than under normal thermic conditions.

• Molecules and Cells
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• 제43권10호
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• pp.848-855
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• 2020

Cells assemble stress granules (SGs) to protect their RNAs from exposure to harmful chemical reactions induced by environmental stress. These SGs release RNAs, which resume translation once the stress is relieved. During stem cell differentiation, gene expression is altered to allow cells to adopt various functional and morphological features necessary to differentiate. This process induces stress within a cell, and cells that cannot overcome this stress die. Here, we investigated the role of SGs in the progression of stem cell differentiation. SGs aggregated during the neuronal differentiation of human bone marrow-mesenchymal stem cells, and not in cell lines that could not undergo differentiation. SGs were observed between one and three hours post-induction; RNA translation was restrained at the same time. Immediately after disassembly of SGs, the expression of the neuronal marker neurofilament-M (NF-M) gradually increased. Assembled SGs that persisted in cells were exposed to salubrinal, which inhibited the dephosphorylation of eukaryotic translation initiation factor 2 subunit 1 (eIF2α), and in eIF2α/S51D mutant cells. When eIF2α/S51A mutant cells differentiated, SGs were not assembled. In all experiments, the disruption of SGs was accompanied by delayed NF-M expression and the number of neuronally differentiated cells was decreased. Decreased differentiation was accompanied by decreased cell viability, indicating the necessity of SGs for preventing cell death during neuronal differentiation. Collectively, these results demonstrate the essential role of SGs during the neuronal differentiation of stem cells.

• Journal of Advanced Marine Engineering and Technology
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• 제35권4호
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• pp.414-420
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• 2011

평균전류밀도 0~2000 $A/m^2$ 의 운전범위에 대한 음극 지지형 고체산화물 연료전지의 단위셀에 대한 열응력해석을 수행하였다. 평균전류밀도가 2000 $A/m^2$ 운전에서, 단위전지 열유동에 대한 수치해석적 방법으로 얻어진 온도분포를 토대로 구조해석을 수행하였다. 온도 편차가 매우 미미한 상태 에서 이러한 유체-구조 연성 해석 방법을 통하여 완전 결합된 조건에서 최대등가응력이 전해질은 262.58MPa, 캐소드는 28.55MPa, 애노드는 15.1MPa로 계산되어 전해질에서 가장 높은 응력이 발생함 을 알 수 있었다. 또한, 마찰접합조건인 경우 마찰계수가 증가함에 따라 응력이 증가함을 알 수 있었으며, 이는 셀 내부 물질간의 결합력에 의한 응력이 지배적임을 알 수 있었다.

• Fisheries and Aquatic Sciences
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• 제19권4호
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• pp.18.1-18.10
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• 2016

In this study, to clarify the function of $PoPLC-{\beta}1$, in response to stress challenge, we examined the $PoPLC-{\beta}1$ expression pattern in response to external stress (pathogen-associated molecular pathogen challenge and environmental challenge including temperature and salinity). $PoPLC-{\beta}1$ expression analysis of tissue from olive flounder showed that the messenger RNA (mRNA) was predominantly expressed in the brain, heart, eye, liver, spleen, and stomach. We also tested the mRNA expression of the $PoPLC-{\beta}1$ in the spleen and kidney of olive flounder by RT-PCR and real-time PCR following stimulation with lipopolysaccharide (LPS), concanavalin A (ConA), or polyinosinic:polycytidylic acid (PolyI:C) and compared with the inflammatory cytokines IL-1b and IL-6 in the stimulated flounder tissues. Each of the spleen and kidney and mRNA transcripts of $PoPLC-{\beta}1$ were increased 30- and 10-fold than normal tissue at 1-6 h post injection (HPI) with PolyI:C when the expression of $PoPLC-{\beta}1$ transcript was similar to LPS and ConA. We also tested the expression of $PoPLC-{\beta}1$ in response to temperature and salinity stress. The expression of $PoPLC-{\beta}1$ also was affected by temperature and salinity stress. Our results provide clear evidence that the olive flounder $PLC-{\beta}1$ signal pathways may play a critical role in immune function at the cellular level and in inflammation reactions. In addition, $PLC-{\beta}1$ appears to act as an oxidative-stress suppressor to prevent cell damage in fish.

• 대한한방부인과학회지
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• 제37권3호
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• pp.63-84
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• 2024

Objectives: This study aims to understand the stress patterns and coping behaviors of women with infertility and to improve existing infertility stress assessment tools to develop a tool suited for Korean society. Methods: The study involved 10 women diagnosed with primary or secondary infertility. Data were collected through surveys and in-depth interviews. Participants were recruited voluntarily, and snowball sampling was used for additional recruitment. Data collection occurred from September 2023 to April 2024. Data analysis included Spearman's rank correlation, Mann-Whitney U test, and Kruskal-Wallis test. Interview results were analyzed using text mining and network analysis with Python 3.12. Results: There was a significant correlation between IVF/ICSI treatment and resilience scores, with non-IVF/ICSI groups showing higher resilience scores. Existing infertility stress assessment tools were generally useful but had limitations, such as discomfort with religious expressions and fixed gender roles, as well as issues with the number of items and response scales. Text mining of interview responses revealed key stress-related keywords including worry, depression, burden, pregnancy outcome, and health. Main stressors included uncertainty about pregnancy outcomes, physical discomfort during treatments, economic burdens, and emotional reactions from family and social relationships. Conclusions: This study identified the stress patterns of women with infertility through interviews. It showed the need for a new assessment tool to evaluate and support the complex stressors experienced by these women. Developing a comprehensive tool is essential for better understanding and managing the various stress factors faced by infertile women.

• 대한간호학회지
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• 제24권3호
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• pp.448-460
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• 1994

This study was conducted to investigate risk factors for senile dementia as well as care givers' stresses and thier needs for nursing care. It was done using a retrospective survey. A convenience sample or In senile dementia patients and l20 nor-mal elders in a rural area was used. The tools used in the study were the MMSE-K(Mini-Mental State Examination-Korea) for dementia screening test and a questionaire developed by the research team. Data were collected through home visits by Com-munity Health Practitioners. Data were analyzed using descriptive statistics, T-test, and Chi-square test. The findings are as follows : 1. There were significant differences in age, marital status, and religions between the two groups. 2. There was a significant difference in smoling behavior between the two groups. 3. There was a significant difference in past his-tory of cancer between groups. 4. There was a significant difference in past and present elderftmily relationship between the two groups. 5. There were significant differences in intellectual activities, assuming major role in family and seeking other's help in daily life troubles between the two groups. 6. There were significant differences in stress factors such as child problem, family conflict, health problem and illegal behavior between the two groups. 7. The major problems out by families in caring for dementia patient were catastrophic reactions, dirtiness, mood change, devouring and tremor. The most serious problems faced by families was dirtiness. with catastrophic reactions, sleep distrubance, changeableness, and a suspcio-usness following. The care givers expressed chronic fatigue, anxiety, tension, depression, disorder in daily life, shamefulness, blame from neighbours and guiltiness. 8. There is need for geriatric hospitals, nursing homes, burden sharing, and counselling or education for family care givers. A replicate study in the urban area is recommended to validate the findings of this study. To explore the impact of stress in life and ‘han’ on senile dementia, a qualitative study is recommended.

• 약학회지
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• 제46권6호
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• pp.466-471
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• 2002

Oxidative stress is considered to be associated with many diseases, such as inflammatory and cardiovascular diseases, aging and cancer. An important etiological mechanism of these diseases may be a causal relationship between the presence of oxidants and the generation of lipid hydroperoxides derived from enzymatic reactions or xenobiotic metabolism. The hydroperoxides can be decomposed to alkoxy- (ROㆍ) and peroxy- (ROOㆍ) free radicals that can oxidize other cell components, resulting in changes in enzyme activity or the generation of mediators, which can cause further cell damage. The aim of this study was to evaluate the ability of aqueous extract from the roots of Platycodon grandiflorum A. DC (Campanulaceae), Changkil (CK), to affect cellular response in primary cultures of rat hepatocytes to t-butyl hydroperoxide (t-BHP) induced oxidative stress and hepatotoxicity. CK-treated cells showed an increased resistance to oxidative challenge, as revealed by a higher percent of survival capacity in respect to control cells. CK reduced t-BHP-enhanced lipid peroxidation measured as production of malondialdehyde and enhanced intracellular reduced glutathione depletion by t-BHP. Furthermore, CK protected from the t-BHP-induced intracellular generation of reactive oxygen species assessed by monitoring dichlorodihydrofluorescein fluorescence. It can be concluded that CK exerts an antioxidant action inside the cell, responsible for the observed modulation of the cellular response to oxidative challenge, and CK have a marked antioxidative and hepatoprotective potency.

• 한국의류학회지
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• 제39권6호
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• pp.812-825
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• 2015

This study explored various issues related to the quality-of-life for obese Korean men. In-depth interviews were conducted with thirty men over BMI 25 whose age ranged from 20's to 50's. Projective techniques along with semi-structured interviews were used. The results of interviews were analyzed based on grounded theory. "Stress" was the main phenomenon resulting from the causal conditions of obesity and stigma. Stress consisted of social, psychological, physical and environmental factors. Contextual conditions mediating the relationship between causal conditions and main phenomenon were obesity level, pressure, and public appearance. Avoidance, change of personal traits, and insensitivity were the action/reactions to the main phenomenon. Various factors due to obesity disappeared and quality-of-life increased when they succeed in weight reduction; however, factors related to obesity and lowered condition of quality-of-life continued if they experienced a weight gain/loss yo-yo.