• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.59-65
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• 2015

Background: After the Fukushima accident, the importance of hazard analysis for extreme external events was raised. Methods: To analyze typhoon-induced hazards, which are one of the significant disasters of East Asian countries, a statistical analysis using the extreme value theory, which is a method for estimating the annual exceedance frequency of a rare event, was conducted for an estimation of the occurrence intervals or hazard levels. For the four meteorological variables, maximum wind speed, instantaneous wind speed, hourly precipitation, and daily precipitation, the parameters of the predictive extreme value theory models were estimated. Results: The 100-year return levels for each variable were predicted using the developed models and compared with previously reported values. It was also found that there exist significant long-term climate changes of wind speed and precipitation. Conclusion: A fragility analysis should be conducted to ensure the safety levels of a nuclear power plant for high levels of wind speed and precipitation, which exceed the results of a previous analysis.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.138-145
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• 2011

In this paper time series wave data are simulated by the Monte Calo method using random numbers to generate random phases of the wave signal. The simulated wave signasl are used to study the characteristics of freak waves. Various sea states are represented by combinations of the significant wave height $H_s$ defined in the spectrum method and the significant wave steepness $S_s$. For a fixed value of $S_s$, the probability of the occurrence of the freak wave is decreased as $H_s$ increases. For a fixed value of $H_s$ the probability of the occurrence of the freak wave increases as $S_s$ increases. The average value of the maximum wave height increase as $S_s$ increases, but the average height of freak wave remains the same and the value approaches two times of $H_s$. For the fixed value of $S_s$, average kurtosis of wave elevation increases as $H_s$ increases, but for a fixed $H_s$, the average kurtosis decreases as $S_s$ increases. The average of abnormality index(AI) is around 2.11 irregardless of $H_s$ and $S_s$. The maximum value of AI lies between 2.5 - 3.0. Therefore it is conjectured that AI maximum due to linear focusing is 3.0.

• Nuclear Engineering and Technology
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• v.55 no.2
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• pp.408-420
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• 2023

Beryllium oxide (BeO) is being re-emphasized and utilized in Micro Modular Reactors (MMR) because of its prominent nuclear and high temperature properties in recent years. The implications of the research about effects of neutron irradiation on the microstructure and properties of BeO are significant. This article comprehensively reviews the effects of neutron irradiation on BeO and proposes the maximum permissible neutron doses at different temperatures for BeO without cracks in appearance according to the data in the previous literature. This maximum permissible neutron dose value has important reference significance for the experimental study of BeO. The effects of neutron irradiation on the thermal conductivity and flexural strength of BeO are also discussed. In addition, microstructure evolution of irradiated BeO during post-irradiation annealing is summarized. This review article has important implications for the application of BeO in MMR.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.59-63
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• 2010

Purpose: Driving a car is an essential component of daily life. For safe driving, each driver must perceive sensory information and respond rapidly and accurately. Brake response time (BRT) is a particularly important factor in the total stopping distance of a vehicle, and therefore is an important factor in traffic accident prevention research. The purpose of the current study was (1) to compare accelerometer. BRTs analyzed by three different methods and (2) to investigate possible correlations between accelerometer-BRTs and foot switch-BRTs, which are measured method using a foot switch. Methods: Eighteen healthy subjects participated in this study. BRT was measured with either a tri-axial accelerometer or a footswitch. BRT with a tri-axial accelerometer was analyzed using three methods: maximum acceleration time, geometrical center, and center of maximum and minimum acceleration values. Results: Both foot switch-BRTs and accelerometer-BRTs were delayed. ANOVA for accelerometer BRTs yielded significant main effects for axis and analysis, while the interaction effect between axis and analysis was not significant. Calculating the Pearson correlation between accelerometer-BRT and foot switch-BRT, we found that maximum acceleration time and center of maximum and minimum acceleration values were significantly correlated with foot switch-BRT (p<0.05). The X axis of the geometrical center was significantly correlated with foot switch-BRTs (p<0.05), but Y and Z axes were not (p>0.05). Conclusion: These findings suggest that the maximum acceleration time and the center of maximum and minimum acceleration value are significantly correlated with foot switch-BRTs.

• PNF and Movement
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• v.19 no.1
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• pp.105-113
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• 2021

Purpose: The purpose of this study was to investigate the effect of trunk-stabilization training using stabilizing reversal and rhythmic stabilization techniques of PNF on trunk muscle strength and respiratory function in elderly stroke patients. Methods: There were 26 stroke patients included in the study. Patients were divided into two groups, and all patients performed exercise 30 min five times per week for six weeks. The experimental group performed trunk stability exercise using stabilizing reversal and rhythmic stabilization techniques of PNF, and the control group performed flexibility and strength training. Trunk muscle strength, forced vital capacity, maximum inspiratory pressure, and maximum expiration pressure were measured to determine the changes after the intervention. For statistical processing, a paired t-test was performed within the group, and the value after intervention was performed as an independent t-test to find out the difference between the two groups. Results: In the experimental group, all of the trunk muscle strength, forced vital capacity, maximum inspiratory pressure, and maximum expiration pressure showed significant differences according to the intervention. In the control group, there were statistically significant differences in trunk muscle strength and forced vital capacity, but the maximum inspiratory pressure and the maximum expiration pressure did not show any statistical change. Conclusion: From these results, it can be seen that the trunk stability exercises that use the proprioceptive neuromuscular promotion method of stable reversal and rhythm stabilization can be a good intervention for the respiratory function of stroke patients.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.2
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• pp.95-100
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• 2022

PURPOSE: The purpose of this study was to compare the effect of depending on the location of applying chest expansion resistance exercise on the respiratory muscle strength stroke patients, and to suggest more effective interventions to improve respiratory function in stroke patients in clinical practice. METHODS: A total of 30 subjects were selected and divided into two groups, and chest cage extension resistance exercise was applied to the sternum and rib cage, respectively, and performed for 4 weeks, 3 times a week, for 20 minutes. In order to compare the general characteristics of the study subjects and the homogeneity of the group, the pre-experimental values were analyzed using the independent sample t-test. Paired-sample t-test was used for pre-post value comparison of maximum inspiratory pressure and maximum expiratory pressure in each group. Statistical significance was set to .05. RESULTS: Both the sternum application group and the rib cage application group showed a significant difference in the maximum inspiratory pressure according to the intervention. Also, there was a statistically significant difference in the maximum expiratory pressure in the sternum application group. CONCLUSION: As breathing exercise is important for stroke patients, based on the results of this study, if therapists perform sternal extension resistance exercise or rib extension resistance exercise according to the patient's condition and environment, it can help the breathing function of stroke patients.

• Journal of Environmental Science International
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• v.28 no.7
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• pp.617-627
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• 2019

This study investigated the relationship between heat-related illnesses obtained from healthcare big data and daily maximum temperature observed in seven metropolitan cities in summer during 2013~2015. We found a statistically significant positive correlation (r = 0.4~0.6) between daily maximum temperature and number of the heat-related patients from Pearson's correlation analyses. A time lag effect was not observed. Relative Risk (RR) analysis using the Generalized Additive Model (GAM) showed that the RR of heat-related illness increased with increasing threshold temperature (maximum RR = 1.21). A comparison of the RRs of the seven cities, showed that the values were significantly different by geographical location of the city and had different variations for different threshold temperatures. The RRs for elderly people were clearly higher than those for the all-age group. Especially, a maximum value of 1.83 was calculated at the threshold temperature of $35^{\circ}C$ in Seoul. In addition, relatively higher RRs were found for inland cities (Seoul, Gwangju, Daegu, and Daejeon), which had a high frequency of heat waves. These results demonstrate the significant risk of heat-related illness associated with increasing daily maximum temperature and the difference in adaptation ability to heat wave for each city, which could help improve the heat wave advisory and warning system.

• Korean Journal of Radiology
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• v.21 no.12
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• pp.1355-1366
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• 2020

Objective: We aimed to evaluate the diagnostic value and prognostic relevance of FDG positron emission tomography/computed tomography (PET-CT) in extrahepatic cholangiocarcinoma patients. Materials and Methods: This study included 234 extrahepatic cholangiocarcinoma patients who underwent FDG PET-CT between June 2008 and February 2016. The diagnostic performance of FDG PEG-CT was compared to that of contrast-enhanced multidetector row CT (MDCT) and MRI. Independent prognosticators for poor survival were also assessed. Results: The sensitivity of FDG PET-CT for detecting primary tumor and regional lymph node metastases was lower than that of MDCT or MRI (p < 0.001), whereas the specificity and positive predictive value for detecting regional lymph nodes metastases was significantly better in FDG PET-CT compared to MDCT and MRI (all p < 0.001). There was no significant difference in the diagnostic yield of distant metastases detection among three diagnostic imaging techniques. In a multivariate analysis, maximum standardized uptake values (SUV_max) of the primary tumor (adjusted hazard ratio [HR], 1.75; 95% confidence interval [CI], 1.13-2.69) and of the metastatic lesions ≥ 5 (adjusted HR, 8.10; 95% CI, 1.96-33.5) were independent contributors to poor overall survival in extrahepatic cholangiocarcinoma patients. In a subgroup analysis of 187 patients with periductal infiltrating type of cholangiocarcinoma, an SUV_max of the primary tumor ≥ 5 was associated with an increased risk of regional lymph node (adjusted odds ratio [OR], 1.60; 95% CI, 0.55-4.63) and distant metastases (adjusted OR, 100.57; 95% CI, 3.94-2567.43) at diagnosis as well as with poor overall survival (adjusted HR, 1.81; 95% CI, 1.04-3.15). Conclusion: FDG PET-CT showed lower sensitivity for detecting primary tumor and regional lymph node involvement than MDCT and MRI. However, the SUV_max of primary tumors and metastatic lesions derived from FDG PET-CT could have significant implications for predicting prognoses in extrahepatic cholangiocarcinoma patients.

• Journal of the Korean Dietetic Association
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• v.4 no.1
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• pp.76-87
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• 1998

The purpose of this study was to examine the nutrition knowledge and attitude of the elderly for developing nutrition education program. The nutrition knowledge test was consisted of nutrition, nutrients, weight control, food safety, and shopping tips by developing the table of specifications. The nutrition attitude test was comprised of seventeen questions for invention, self-efficacy, control, and outcome expectation. A total of 140 elderly living at home responded to both nutrition knowledge and attitude test. According to the results of nutrition knowledge test, the mean was 13.3 at the maximum 18 points and 51.4% respondents got more than 14 points. Significant differences were found with age (p<0.05, $x^2$=21.46), charge of income (p<0.05, $x^2$=8.86) and monthly expenses(p<0.05, $x^2$=22.95). The results of nutrition attitude test showed that the mean value of 40.89 points at the maximum 51 points and 58.6% of respondents rated more than 40.89 points. In exploring the relationship between the demographic variables(sex, age, educational level, and monthly expenses) and for attitude concepts, a significant correlation was found. Correlation among the knowledge for nutrition, nutrients, and the attitudes for nutrition was significant(p<0.05).

• Journal of Industrial Technology
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• v.23 no.A
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• pp.69-81
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• 2003

Numerical analysis is important for the design, construction and maintenance of large caverns. The rock mass contains generally discontinuities such as faults, joints and fissures. The mechanical behavior and geometric characteristics of these discontinuities would have a significant impact on the stability of the caverns. In this research the Distinct Element Method(DEM) was used to analyze the structural stability of the large cavern. The Barton-Bandis Joint Model (B-B J.M) was used as a constitutive model for the joint. In addition, two different cases 1) analysis with a support system and 2) analysis with no support system, were analyzed to optimize a support system and to investigate reinforcing effects of a support system. The most significant parameters of in-situ stress, JRC of in-situ natural joints, and spatial distribution characteristics of discontinuities were acquired through field investigation. Displacement (horizontal, joint shear), maximum joint opening, maximum and minimum principal stresses, range of relaxed zone, rockbolt axial forces and shotcrete stresses were calculated at each excavation stage. As a result of analysis the calculated values proved to be under the allowable value Rockbolts also proved to be an efficient support measure to control joint shear displacement which had significant effects on extending the relaxed zone. As a consequence, the structural stability of the cavern was assured with an appropriate support system.