• Journal of Nutrition and Health
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• 제30권8호
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• pp.920-929
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• 1997

This study examined the effect of dietary salt levels on the incidence and cure of gastric ulcer in rats. Two sets of experiment were conducted . In the first experiment, the rats were divided into 3 groups. The 3 groups were fed 0%, 4%, and 8% NaCl diets respectively for 20days. The rats were given water -immersion restraint stress at the end of the dietary period , and sacrificed. The ulcer index by histological test was higher in rats fed the 8% NaCl diet than those in the other groups. The hexosamine and glutathione levels were significantly lower in the rats fed the 8% NaCl diet. Hematocrit and total iron binding capacity(TIBC) showed lower values caused by bleeding of gastric mucosa. The second experiment was designed to determine the effect of soldium concentration on the cure of gastric ulcer . As the gastric ulcer was recovered, ulcer length was gradually deceased in the control group but not changed in the 8% NaCl diet group. The gastric hexosamine and hepatic glutathione were increased in the control group but decreased in the 8% NaCl diet group. The hematologic indices of stressed rats showed the same tendency. As a result, dietary salt per se did not cause gastric ulcer . Once an ulcer is formed by stress or any other factor, higher levels of dietary salt may be detrimental to gastric mucosa, thereby delaying the healing of the ulcer. It is recommended that dietary salt intake be reduced in stress-prone people.

• Geomechanics and Engineering
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• 제34권1호
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• pp.43-49
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• 2023

Knowledge of minimum horizontal stress (S_hmin) is a significant step in determining full stress tensor. It provides crucial information for the production of sand, hydraulic fracturing, determination of safe mud weight window, reservoir production behavior, and wellbore stability. Calculating the S_hmin using indirect methods has been proved to be awkward because a lot of data are required in all of these models. Also, direct techniques such as hydraulic fracturing are costly and time-consuming. To figure these problems out, this work aims to apply the long-short-term memory (LSTM) algorithm to S_hmin time-series prediction. 13956 datasets obtained from an oil well logging operation were applied in the models. 80% of the data were used for training, and 20% of the data were used for testing. In order to achieve the maximum accuracy of the LSTM model, its hyper-parameters were optimized significantly. Through different statistical indices, the LSTM model's performance was compared with with other machine learning methods. Finally, the optimized LSTM model was recommended for S_hmin prediction in the well logging operation.

• 임상간호연구
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• 제19권2호
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• pp.285-297
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• 2013

Purpose: This study was conducted to investigate the differences in sleep disturbance, stress, self-efficacy and depression by fatigue level and to identify the factors influencing fatigue in hemodialysis patients. Methods: This study used a cross-sectional design and the subjects were 195 patients undergoing hemodialysis in a local unit. Data were collected using a structured questionnaire and medical records from June to August 2012. The data were analyzed using descriptive statistics, independent t-test, one way ANOVA, $Scheff{\grave{e}}$ test, and Pearson's correlation coefficients. Also a multiple regression analysis was used to assess the independent association between fatigue status and indices of sleep disturbance, stress, self-efficacy and depression. Results: A total of 99 (50.8%) subjects experienced a high level of fatigue and 96 (49.2%) experienced a low level of fatigue. There were significant differences in the levels of sleep disturbance, stress, self-efficacy and depression between the two groups. Fatigue was significantly correlated to sleep disturbance, stress, self-efficacy and depression. The most important factor related to fatigue was stress, followed by sleep disturbance. These factors explained about 37% of fatigue of the respondents. Conclusion: The results of this study showed that sleep disturbance and stress were significant predictors of fatigue in hemodialysis patients. Possible interventions for minimizing fatigue in patients undergoing long-term hemodialysis should be aimed to manage the known contributing factors.

• Safety and Health at Work
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• 제10권2호
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• pp.205-212
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• 2019

Background: Workforce health is one of the primary and most challenging issues, particularly in industrialized countries. This article aims at modeling the major factors affecting accidents in the workplace, including general health, work-family conflict, effort-reward imbalance, and internal and external locus of control. Methods: A cross-sectional study was conducted in Esfahan Steel Company in Iran. A total of 450 participants were divided into two groups-control and case-and the questionnaires were distributed among them. Data were collected through a 7-part questionnaire. Finally, the results were analyzed using SPSS 22.0 and Amos software. Results: All the studied variables had a significant relationship with the accident proneness. In the case group, general health with a coefficient of -0.37, worke-family conflict with 0.10, effort-reward imbalance with 0.10, internal locus of control with -0.07, and external locus of control with 0.40 had a direct effect on occupational stress. Occupational stress also had a positive direct effect on accident proneness with a coefficient of 0.47. In addition, fitness indices of control group showed general health (-0.35), worke-family conflict (0.36), effort-reward imbalance (0.13), internal locus of control (-0.15), and external locus of control (0.12) have a direct effect on occupational stress. Besides, occupational stress with a coefficient of 0.09 had a direct effect on accident proneness. Conclusion: It can be concluded that although previous studies and the present study showed the effect of stress on accident and accident proneness, some hidden and external factors such as work-family conflict, effort-reward imbalance, and external locus of control that affect stress should also be considered. It helps industries face less occupational stress and, consequently, less occurrence rates of accidents.

• 스트레스연구
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• 제27권2호
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• pp.199-204
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• 2019

본 연구는 불안민감도가 과제수행과 스트레스 반응에 미치는 영향을 살펴보고, 이 과정에 우울감은 어떠한 영향을 미치는지 확인하였다. 참가자들은 제한된 시간에 암산 문제를 완수하였고, 불안민감도지수와 우울증 선별도구에 응답하였다. 더불어, 실험 전후 참가자들의 코르티졸(Cortisol) 변화량을 확인하였다. 그 결과, 불안민감도가 높은 사람은 과제수행의 정확도가 떨어지고 코르티졸 수치가 유의미하게 상승하였다. 또한, 불안민감도와 우울감이 모두 높은 참가자들이 코르티졸 수치가 가장 크게 상승하였다. 본 연구는 자기보고식 응답에 근거하여 임상증상을 기술하는 것을 넘어 과제수행의 정확도와 생화학적 지표를 함께 제시함으로써, 보다 안정적으로 개인의 불안민감도와 우울감의 관계를 논의하였다는 의의를 지닌다.

• Structural Engineering and Mechanics
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• 제59권1호
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• pp.101-122
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• 2016

Elasticity solutions for bi-directional functionally graded beams subjected to arbitrary lateral loads are conducted, with emphasis on the end effects. The material is considered macroscopically isotropic, with Young's modulus varying exponentially in both axial and thickness directions, while Poisson's ratio remaining constant. In order to obtain an exact analysis of stress and displacement fields, the symplectic analysis based on Hamiltonian state space approach is employed. The capability of the symplectic framework for exact analysis of bi-directional functionally graded beams has been validated by comparing numerical results with corresponding ones in open literature. Numerical results are provided to demonstrate the influences of the material gradations on localized stress distributions. Thus, the material properties of the bi-directional functionally graded beam can be tailored for the potential practical purpose by choosing suitable graded indices.

• 국제강구조저널
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• 제18권4호
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• pp.1384-1396
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• 2018

One of the failure modes observed in steel yield energy dissipating devices (SYEDs) excited by a strong earthquake would be the low-cycle fatigue failure. Fatigue cracks of a SYED are prone to initiate at the notch areas where stress concentration is usually occurred, which is demonstrated by the cyclic tests and analyses carried out for this study. Since the fatigue failure of SYEDs dramatically deteriorates their structural capacities, the thorough investigation on their fatigue life is usually required. To do this, sophisticated modeling with considering a time-consuming and complicate fracture mechanism is generally needed. This study makes an effort to investigate the low-cycle fatigue life of SYEDs predicted by a simplified method utilizing damage indices and fatigue prediction equations that are based on the plastic strain amplitudes obtained from typical finite element analyses. This study shows that the low-cycle fatigue failure of SYEDs predicted by the simplified method can be conservatively in good agreement with the test results of SYED specimens prepared for experimental validation.

• 문화기술의 융합
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• 제6권4호
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• pp.253-258
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• 2020

우울증은 전 세계적으로 유병율이 증가하고 있으며, 고혈압과 같은 여러 질병들뿐만 아니라 사망률과도 연관성이 높은 질병이다. 본 연구의 목적은 한국인 성인 중 단순노무종사자 직업군에서 우울증과 연관성이 있는 임상학적 위험지표를 발굴하는 것이다. 이러한 연구를 위한 데이터로는 질병관리본부 국민건강영양조사 7기 (2016-2018) 데이터가 사용되었다. 우울증과 인구학적 정보와의 연관성에서는 나이, 성별, 스트레스 인지정도, 스트레스 인지율 지표들이 우울증과 매우 높은 통계적 연관성이 나타났고, 교육과 결혼유무도 우울증과 연관성이 있는 것으로 나타났다. 복부둘레 및 체질량지수와 같은 비만 지표들은 우울증과 연관성이 없는 것으로 나타났다. 혈액정보 중 hemoglobin과 hematocrit은 우울증과 연관성이 매우 높은 것으로 나타났으며, 성별과 나이로 보정한 분석에서도 통계적 유의성이 유지되었다. 본 연구결과는 향후 단순노무종사자 직업군의 우울증 예방 및 치료를 위한 정보로 활용가능할 것이다.

• 대한원격탐사학회지
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• 제40권1호
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• pp.45-56
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• 2024

Faced with aging populations, declining resources, and limited agricultural productivity, rural areas in South Korea require innovative solutions. This study investigated the potential of drone-based vegetation indices (VIs) to analyze soybean growth patterns in open-field smart agriculture in Goesan-gun, Chungbuk Province, South Korea. We monitored multi-seasonal normalized difference vegetation index (NDVI) and the normalized difference red edge (NDRE) data for three soybean lots with different irrigation methods (subsurface drainage, conventional, subsurface drip irrigation) using drone remote sensing. Combining NDVI (photosynthetically active biomass, PAB) and NDRE (chlorophyll) offered a comprehensive analysis of soybean growth, capturing both overall health and stress responses. Our analysis revealed distinct growth patterns for each lot. LotA(subsurface drainage) displayed early vigor and efficient resource utilization (peaking at NDVI 0.971 and NDRE 0.686), likely due to the drainage system. Lot B (conventional cultivation) showed slower growth and potential limitations (peaking at NDVI 0.963 and NDRE 0.681), suggesting resource constraints or stress. Lot C (subsurface drip irrigation) exhibited rapid initial growth but faced later resource limitations(peaking at NDVI 0.970 and NDRE 0.695). By monitoring NDVI and NDRE variations, farmers can gain valuable insights to optimize resource allocation (reducing costs and environmental impact), improve crop yield and quality (maximizing yield potential), and address rural challenges in South Korea. This study demonstrates the promise of drone-based VIs for revitalizing open-field agriculture, boosting farm income, and attracting young talent, ultimately contributing to a more sustainable and prosperous future for rural communities. Further research integrating additional data and investigating physiological mechanisms can lead to even more effective management strategies and a deeper understanding of VI variations for optimized crop performance.

• 대한간호학회지
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• 제45권2호
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• pp.211-220
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• 2015

Purpose: This study was done to develop a prediction model for postpartum depression by verifying the mediation effect of antepartum depression. A hypothesized model was developed based on literature reviews and predictors of postpartum depression by Beck. Methods: Data were collected from 186 pregnant women who had a gestation period of more than 32 weeks and were patients at a maternity hospital, two obstetrics and gynecology specialized hospitals, or the outpatient clinic of K medical center. Data were analysed with descriptive statistics, correlation and exploratory factor analysis using the SPSS/WIN 18.0 and AMOS 18.0 programs. Results: The final modified model had good fit indices. Parenting stress, antepartum depression and postpartum family support had statistically significant effects on postpartum depression, and defined 74.7% of total explained variance of postpartum depression. Antepartum depression had significant mediation effects on postpartum depression from stress in pregnancy and self-esteem. Conclusion: The results of this study suggest that it is important to develop nursing interventions including strategies to reduce parenting stress and improve postpartum family support in order to prevent postpartum depression. Especially, it is necessary to detect and treat antepartum depression early to prevent postpartum depression as antepartum depression can affect postpartum depression by mediating antepartum factors.