• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.31-40
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• 1995

We compared stress/rest myocardial Tc-99m-MIBl tomographic image findings with rest/stress rubidium-82 tomographic images. In 23 patients with coronary artery disease (12 of them received bypass grafts before) and 6 normal subjects, rest rubidium PET study was performed : rubidium-82 and Tc-99m-MIBI were injected simultaneously to each patient after dipyridamole stress for rubidium PET and MIBI SPECT; and rest MIBI SPECT was performed 4 hours thereafter. We scored segmental decrease of rubidium or MIBI uptakes into 5 grades for 29 segments from 3 short-axis, vertical and horizontal slices. Scores were summed for each major arterial territory. When more score than two grade-2's or one grade-3 was considered as the cue for significant stenosis for major arterial territories, 67% of 46 stenosed arteries were found with MIBI studies and 78% of them by rubidium studies. Fourteen among 28 grafted arterial territories of 12 post-CABG patients were found normal with both rubidium and MIBI. Segmental scores were concordant between rubidium and MIBI in 72% of 709 stress segments and in 80% of 825 rest segments. Stress rubidium segmental scores were less than stress MIBI scores in 9%, so were rest rubidium scores. Stress rubidium scores were more than stress MIBI scores in 20% of segments, and rest rubidium segmental scores were more than rest MIBl scores in 11%. Rank correlations (Spearman's rho's more than 0.7(stress) and 0.5(rest), slopes (MIBI/rubidium) around 0.7(stress) and 0.9 (rest)) suggested deeper and wider defects in stress with rubidium. Slope over 1 (MIBI/rubidium) with LAD segemental scores at rest and 7 territories which had much larger score with MIBI revealed exaggeration of rest defects with rest MIBI in same-day stress/rest study. Difference scores (stress-rest for each territory) suggesting Ischemia were larger with rubidium (slope of MIBI/rubidium around 0.45). As has been implied by animal or separate-day-human studies, these segmental analyses with simultaneous examination in patients told that rubidium PET flow studies disclose ischemia more often than MIBI studies and that rest MIBI studies in same-day stress/rest-sequence gave a little larger rest defect than they would have shown.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.4
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• pp.423-428
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• 2016

The last stage blades of a low pressure (LP) turbine get frequently fractured because of stress corrosion cracking. This is because they operate in a severe corrosive environment that is caused by the impurities dissolved in condensed steam and high stress due to high speed rotation. To improve the reliability of the blades under severe conditions, 12% Cr martensitic stainless steel, having excellent corrosion resistance and higher strength, is widely used as the blade material. This paper shows the result of root cause analysis on a blade which got fractured suddenly during normal operation. Testing of mechanical properties and microstructure examination were performed on the fractured blade and on a blade in sound condition. The results of testing of mechanical properties of the fractured blade showed that the hardness were higher but impact energy were lower, and were not meeting the criteria as per the material certificate specification. This result showed that the fractured blade became embrittled. The branch-type crack was found to have propagated through the grain boundary and components of chloride and sulfur were detected on the fractured surface. Based on these results, the root cause of fracture was confirmed to be stress corrosion cracking.

• Science of Emotion and Sensibility
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• v.22 no.3
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• pp.21-34
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• 2019

This study was an examination of the relevance and clinical significance of electroencephalographic (EEG) indexes (e.g., mental/physical stress and attention) and indexes of heart rate variability (HRV) with regard to cognitive function and physiological health conditions in elderly people. A device was used to record two-channel EEGs of the frontal lobe and a one-channel ECG simultaneously. Subjects were 76 people average aged 73. The significant findings are as follows: First, subjects whose intrinsic alpha rhythm had high amplitude, regardless of peak, showed higher resistance to mental stress and lower physical stress than did subjects with low-amplitutde intrinsic alpha rhythm. Second, HRV, SDNN, and RMSSD indexes showed strong positive correlations between the two groups of subjects regardless of the division of groups. Third, the alpha asymmetry of the left and right sides of the brain in subjects with low-amplitude intrinsic alpha rhythm was larger, and the delta/alpha ratio (reflecting physical stress) and theta/sensorimotor rhythm (SMR) ratio (showing the decline in attention) were bigger. Fourth, the subjects in whom intrinsic alpha rhythm peak occurred during slow rhythm had a higher theta/SMR ratio than did subjects whose peak occurred during fast rhythm, which was related to a steeper decline in attention. Therefore, the presence or absence of intrinsic alpha rhythm peak and amplitude on quantitative EEG may be an index reflecting the cognitive function and physiological health of elderly people.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.88-91
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• 2002

The two dimensional size effect of specimen gauge section (length x width) was investigated on the compressive behavior of a T300/924 [45/-45/0/90]3s, carbon fiber-epoxy laminate. A modified ICSTM compression test fixture was used together with an anti-buckling device to test 3mm thick specimens with a 30$\times$30, 50$\times$50, 70$\times$70, and 90mm$\times$90mm gauge length by width section. In all cases failure was sudden and occurred mainly within the gauge length. Post failure examination suggests that $0^{\circ}$ fiber microbuckling is the critical damage mechanism that causes final failure. This is the matrix dominated failure mode and its triggering depends very much on initial fiber waviness. It is suggested that manufacturing process and quality may play a significant role in determining the compressive strength. When the anti-buckling device was used on specimens, it was showed that the compressive strength with the device was slightly greater than that without the device due to surface friction between the specimen and the device by pretoque in bolts of the device. In the analysis result on influence of the anti-buckling device using the finite element method, it was found that the compressive strength with the anti-buckling device by loaded bolts was about 7% higher than actual compressive strength. Additionally, compressive tests on specimen with an open hole were performed. The local stress concentration arising from the hole dominates the strength of the laminate rather than the stresses in the bulk of the material. It is observed that the remote failure stress decreases with increasing hole size and specimen width but is generally well above the value one might predict from the elastic stress concentration factor. This suggests that the material is not ideally brittle and some stress relief occurs around the hole. X-ray radiography reveals that damage in the form of fiber microbuckling and delamination initiates at the edge of the hole at approximately 80% of the failure load and extends stably under increasing load before becoming unstable at a critical length of 2-3mm (depends on specimen geometry). This damage growth and failure are analysed by a linear cohesive zone model. Using the independently measured laminate parameters of unnotched compressive strength and in-plane fracture toughness the model predicts successfully the notched strength as a function of hole size and width.

• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.41-46
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• 2010

Purpose: Anterior drawer and varus stress test are commonly used for radiologic evaluation of chronic lateral ankle instability. However, there are controversies regarding the method of measurement and the normal value. This study was performed to investigate radiologic normal values in normal Korean adults and to analyze differences by age and gender. Materials and Methods: Sixty Korean adults were recruited and divided in three groups (20 in their twenties, 20 in their thirties, 20 in their forties). There were 10 males and 10 females in each group. The selection criteria were no history of ankle injury and no evidence of instability on physical examination. Radiologic measurement of varus talar tilt and anterior talar translation were performed through anterior and varus stress radiographs using Telos device (150N force). The measurement was repeated twice by three researchers, and intraobserver reproducibility and interobserver reliability were analyzed. The average talar tilt and anterior talar translation were obtained. Results: Talar tilt and anterior talar translation on ankle stress radiographs had good intraobserver reproducibility and interobserver reliability. Talar tilt was average $3.7^{\circ}$ and $5.1^{\circ}$ in male and female of twenties of age, $3.9^{\circ}$ and $4.8^{\circ}$ in their thirties, $3.4^{\circ}$ and $4.5^{\circ}$ in their forties. Anterior talar translation was average 3.5 mm and 4.2 mm in their twenties, 4.1 mm and 3.8 mm in their thirties, 3.6 mm and 4.1 mm in their forties. There was no significant difference in talar tilt and anterior talar translation by age. However, there was significant difference in talar tilt by gender. Conclusion: Normal range of talar tilt angle in Korean adults was below $8.3^{\circ}$, and normal range of anterior talar translation was below 7.6 mm. It seems to be able to serve as a good reference for radiologic evaluation and for treatment of chronic lateral ankle instability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.423-432
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• 2021

This study developed a scale to measure college students' perceived stress levels for adverse life events that may occur in their daily lives and confirmed its validity and reliability. The scale was developed in accordance with DeVellis' scale development guidelines. Data were collected from 1,242 students of a local university in 2020. The collected samples were randomly separated into two groups (A, B). Group A (N=620) was tested for an initial examination of the performance, exploratory factor analysis, multitrait-multimethod matrix, criterion-related validity, and reliability of each item; and verified with group B (N=622) for confirmatory factor analysis and reliability re-test. As a result, the final scale of 33 items and eight factors were developed. The KMO values were 0.92, and Bartlett's spherical test was significant (χ²=12532.42, p<.001); the number of factors with initial eigenvalues of 1.0 or higher was eight; the cumulative factor loadings of 71.5% and the commonality of each item was 0.56 or higher. The reliability of the scale was Cronbach's alpha 0.94; sub-factors' Cronbach's alpha was 0.78 to 0.90. Therefore, these findings suggest that the scale developed in this study would be useful for measuring the stress levels of daily life for college students.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.453-465
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• 2021

This study was attempted to identify factors affecting depression by stress causes. Data from the 2018 Korea National Health and Nutrition Examination Survey were used, total subjects was 2,939. Data were analyzed by complex sample frequency, percentage, x2-test and regression by SPSS 25.0. As a result, in the economic problem group, gender, occupation, health-related quality of life, weight change, smoking, subjective health status and subjective body image were significant influencing factors for depression, and explanatory power was 28.7% (F = 8.23, p < .001). In the parent, child, and spouse problem group, age, health-related quality of life, weight change, and subjective health status were significant, explanatory power was 33.1% (F = 6.92, p <.001). In the self and family health problem group, gender, health-related quality of life, weight change, smoking, and subjective health status were significant, explanatory power was 29.6% (F = 5.74, p < .001). Through the results, the influencing factors that appear differently according to each stress cause can be used as basic data to establish an individualized intervention strategy.

• Korean Journal of Community Nutrition
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• v.26 no.6
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• pp.441-454
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• 2021

Objectives: This study investigated the association between the frequency and pattern of eating alone and the mental health status according to region in Korean adults. Methods: The data of 10,040 Korean adults aged ≥ 19 years from the Korea National Health and Nutrition Examination Survey (KNHANES) 2017 and 2019 were used. Participants were divided into 4 groups based on their frequency of eating alone: none (all meals together), 1, 2, and 3 meals/day alone. The regions were divided into urban and rural areas. Mental health status was assessed by stress recognition, depressive symptoms, and suicidal ideation. Multivariable logistic regressions were conducted to estimate the adjusted odds ratios (AORs) with 95% confidence intervals (CIs) on the association of the frequency and pattern of eating alone with poor mental health after controlling for covariates. Results: Among Korean adults, 74.1% ate more than one meal a day alone. Individuals having 3 meals a day alone tended to be less educated, single, single person households, or living in urban areas (all P < 0.05). In rural areas, those having 3 meals/day alone had higher odds of stress recognition (AOR: 1.55, 95% CI: 1.02-2.35) than those having all meals together. In urban areas, individuals eating alone 3 times/day had higher odds of stress recognition (AOR: 1.60, 95% CI: 1.31-1.96), depressive symptoms (AOR: 1.61, 95% CI: 1.23-2.12), and suicidal ideation (AOR: 2.14, 95% CI: 1.42-3.22) compared to those having all meals together. Urban residents having dinner alone had higher odds of depressive symptoms (AOR: 1.29, 95% CI: 1.05-1.58) and suicidal ideation (AOR: 1.66, 95% CI: 1.19-2.33) than those having dinner with others. Conclusions: Our findings showed that the frequency and patterns of eating alone were differentially associated with increased odds of poor mental health according to region of residence. Nutrition education is needed for those frequently eating alone, particularly those living in urban areas, to highlight the advantages of eating together and to ensure that they have balanced and healthy meals even if they eat alone.

• The Korea Journal of Herbology
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• v.33 no.1
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• pp.47-55
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• 2018

Objectives : The current study is to evaluate the hepatoprotective effect of youngyanggak-san (YGS) on thioacetamide (TAA)-induced acute liver injury in rats. Methods : YGS is composed of Glycyrrhizae Radix, Asiasari Radix, Cimicifugae Rhizoma, Saigae Tataricae Cornu. While N-YGS (non-youngyanggak-san) doesn't include Saigae Tataricae Cornu. Two samples were administrated TAA together for 3 days. Thirty-six rats were divided into four groups. Rats except for the normal group were received TAA (200 mg/kg of body weight, I.P) were divided into three groups (n=9/group) : Group 1 (TAA only), Group 2 (TAA + 200 mg/kg YGS) and Group 3 (TAA + 200 mg/kg N-YGS). Acute liver damage confirmed using histological examination, The factors associated with oxidative stress and liver function activity measured in serum. Also, expressions of inflammation related proteins were investigated by western blot analysis. Results : Oxidative stress factors such as ROS and $ONOO^-$ in the Group 2 was manifested by a significant rise compared with Group 1. YGS markedly decreased the elevated ROS and $ONOO^-$. Furthermore, YGS significantly reduced the levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) The nuclear $factor-{\kappa}B$ ($NF-{\kappa}B$) activation induced by TAA led to increase both inflammatory mediators and cytokines. While YGS administration remarkably suppressed such the overexpression. In addition, the histopathological analysis showed that the liver tissue lesions were improved obviously in YGS treatment. Conclusion : YGS provided a hepatoprotective effect on acute liver damage through the suppression of oxidative stress. Especially, this effect enhanced markedly when Saigae Tataricae Cornu is included.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.7 no.2
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• pp.89-97
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• 2014

Purpose: To evaluate the ultrasonographic findings of the elbows on group screening of middle school baseball players. Materials and Methods: Ninety-three players (age: 12-15, mean 13.5 years) of four middle school baseball team were evaluated with bilateral elbow ultrasonographies in the field regardless of elbow pain. Medial and anterolateral ultrasound examination of the both elbow were performed in the field to detect any abnormalities including medial epicondylar separation or fragmentation and capitellar osteochondritis dissecans respectively. We analyzed the relationship among elbow pain, physical findings and sonographic abnormalities and the differences of sonographic abnormalities between pitchers and fielders. Results: Thirty-six of 93 (39%) players had sonographic abnormalities of elbow in dominant arm, 30 with medial epicondylar apophyseal separation or fragmentation, 2 with osteochondritis dissecans, 4 with both lesions. Twenty-nine of 37 (78%) players with elbow pain had sonographic abnormalities. On physical examination, players with medial epicondylar abnormalities had medial epicondylar tenderness (59%) and pain on valgus stress test (52%), and 5 of 6 (83%) players with osteochondritis dissecans showed flexion contracture more than $5^{\circ}$. The incidence of medial epicondylar abnormalities between pitchers and fielders was statistically not significant but osteochondritis dissecans was more prevalent in pitchers (p<0.05). Conclusion: Elbow sonography is a simple and useful screening tool in the field and also effective for early detection of medial epicondylar abnormalities or osteochondritis dissecans that could be the main causes of elbow pain in adolescent baseball players.