• Title/Summary/Keyword: Physical methods

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Predicting Forest Gross Primary Production Using Machine Learning Algorithms (머신러닝 기법의 산림 총일차생산성 예측 모델 비교)

  • Lee, Bora;Jang, Keunchang;Kim, Eunsook;Kang, Minseok;Chun, Jung-Hwa;Lim, Jong-Hwan
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.21 no.1
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    • pp.29-41
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    • 2019
  • Terrestrial Gross Primary Production (GPP) is the largest global carbon flux, and forest ecosystems are important because of the ability to store much more significant amounts of carbon than other terrestrial ecosystems. There have been several attempts to estimate GPP using mechanism-based models. However, mechanism-based models including biological, chemical, and physical processes are limited due to a lack of flexibility in predicting non-stationary ecological processes, which are caused by a local and global change. Instead mechanism-free methods are strongly recommended to estimate nonlinear dynamics that occur in nature like GPP. Therefore, we used the mechanism-free machine learning techniques to estimate the daily GPP. In this study, support vector machine (SVM), random forest (RF) and artificial neural network (ANN) were used and compared with the traditional multiple linear regression model (LM). MODIS products and meteorological parameters from eddy covariance data were employed to train the machine learning and LM models from 2006 to 2013. GPP prediction models were compared with daily GPP from eddy covariance measurement in a deciduous forest in South Korea in 2014 and 2015. Statistical analysis including correlation coefficient (R), root mean square error (RMSE) and mean squared error (MSE) were used to evaluate the performance of models. In general, the models from machine-learning algorithms (R = 0.85 - 0.93, MSE = 1.00 - 2.05, p < 0.001) showed better performance than linear regression model (R = 0.82 - 0.92, MSE = 1.24 - 2.45, p < 0.001). These results provide insight into high predictability and the possibility of expansion through the use of the mechanism-free machine-learning models and remote sensing for predicting non-stationary ecological processes such as seasonal GPP.

Positron Annihilation Spectroscopy of Active Galactic Nuclei

  • Doikov, Dmytry N.;Yushchenko, Alexander V.;Jeong, Yeuncheol
    • Journal of Astronomy and Space Sciences
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    • v.36 no.1
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    • pp.21-33
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    • 2019
  • This paper focuses on the interpretation of radiation fluxes from active galactic nuclei. The advantage of positron annihilation spectroscopy over other methods of spectral diagnostics of active galactic nuclei (therefore AGN) is demonstrated. A relationship between regular and random components in both bolometric and spectral composition of fluxes of quanta and particles generated in AGN is found. We consider their diffuse component separately and also detect radiative feedback after the passage of high-velocity cosmic rays and hard quanta through gas-and-dust aggregates surrounding massive black holes in AGN. The motion of relativistic positrons and electrons in such complex systems produces secondary radiation throughout the whole investigated region of active galactic nuclei in form of cylinder with radius R= 400-1000 pc and height H=200-400 pc, thus causing their visible luminescence across all spectral bands. We obtain radiation and electron energy distribution functions depending on the spatial distribution of the investigated bulk of matter in AGN. Radiation luminescence of the non-central part of AGN is a response to the effects of particles and quanta falling from its center created by atoms, molecules and dust of its diffuse component. The cross-sections for the single-photon annihilation of positrons of different energies with atoms in these active galactic nuclei are determined. For the first time we use the data on the change in chemical composition due to spallation reactions induced by high-energy particles. We establish or define more accurately how the energies of the incident positron, emitted ${\gamma}-quantum$ and recoiling nucleus correlate with the atomic number and weight of the target nucleus. For light elements, we provide detailed tables of all indicated parameters. A new criterion is proposed, based on the use of the ratio of the fluxes of ${\gamma}-quanta$ formed in one- and two-photon annihilation of positrons in a diffuse medium. It is concluded that, as is the case in young supernova remnants, the two-photon annihilation tends to occur in solid-state grains as a result of active loss of kinetic energy of positrons due to ionisation down to thermal energy of free electrons. The single-photon annihilation of positrons manifests itself in the gas component of active galactic nuclei. Such annihilation occurs as interaction between positrons and K-shell electrons; hence, it is suitable for identification of the chemical state of substances comprising the gas component of the investigated media. Specific physical media producing high fluxes of positrons are discussed; it allowed a significant reduction in the number of reaction channels generating positrons. We estimate the brightness distribution in the ${\gamma}-ray$ spectra of the gas-and-dust media through which positron fluxes travel with the energy range similar to that recorded by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) research module. Based on the results of our calculations, we analyse the reasons for such a high power of positrons to penetrate through gas-and-dust aggregates. The energy loss of positrons by ionisation is compared to the production of secondary positrons by high-energy cosmic rays in order to determine the depth of their penetration into gas-and-dust aggregations clustered in active galactic nuclei. The relationship between the energy of ${\gamma}-quanta$ emitted upon the single-photon annihilation and the energy of incident electrons is established. The obtained cross sections for positron interactions with bound electrons of the diffuse component of the non-central, peripheral AGN regions allowed us to obtain new spectroscopic characteristics of the atoms involved in single-photon annihilation.

Predicting Healthy Lifestyle Patterns in Older Community Dwelling Adults: A Latent Profile Analysis (잠재프로파일 분석을 활용한 한국 노인 라이프스타일 유형화와 영향요인 분석)

  • Park, Kang-Hyun;Yang, Min Ah;Won, Kyung-A;Park, Ji-Hyuk
    • Therapeutic Science for Rehabilitation
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    • v.10 no.2
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    • pp.75-93
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    • 2021
  • Objective : The aim of this study was to identify subgroups of older adults with respect to their lifestyle patterns and examine the characteristics of each subgroup in order to provide a basic evidence for improving the health and quality of life. Methods : This cross-sectional study was conducted in South Korea. Community-dwelling older adults (n=184) above the age of 65 years were surveyed from April 2019 to May 2019. This study used latent profile analysis to examine the subgroups. Chi-squared (χ2) and multinomial logistic regression measures were then used to analyze individual characteristics and influencing factors. Results : The pattern of physical activity which is one of the lifestyle domains in elderly was categorized into three types: 'passive exercise type (31.1%)', 'low intensity exercise type (54.5%)', and 'balanced exercise type(14.5%)'. Activity participation was divided into three patterns: 'inactive type (12%)', 'self-management type (61%)', and 'balanced activity participation type (27%)'. In terms of nutrition, there were only two groups: 'overall malnutrition type (13.5%)' and 'balanced nutrition type (86.5%)'. Furthermore, as a result of the multinomial logistic regression analysis to understand the effects of lifestyle types on the health and quality of life of the elderly, it was confirmed that the health and quality of life were higher in those following an active and balanced lifestyle. In addition, gender, education level and residential area were analyzed as predictive factors. Conclusion : The health and quality of life of the elderly can be improved when they have balanced lifestyle. Therefore, an empirical and policy intervention strategy should be developed and implemented to enhance the health and quality of life of the elderly.

The Effect of Internalized Shame and Self-Control on Interpersonal Relationships in Stroke Patients (내면화된 수치심과 자기통제력이 뇌졸중 환자의 대인관계에 미치는 영향)

  • Hwang, Jung-Ha;Lim, Jae-Ho
    • The Journal of Korean society of community based occupational therapy
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    • v.10 no.3
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    • pp.63-74
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    • 2020
  • Objective : The purpose of this study is to investigate the influence of internal shame and self-control on interpersonal relationships in stroke patients, and to provide evidence and information necessary for clinical trials by analyzing the relationship. Methods : For this study, 150 stroke patients receiving occupational therapy services at institutions where occupational therapists work in Jeollanam-do and Chungnam regions were targeted through email and mail from March 1, 2019 to April 30, 2019. The questionnaire was conducted using general characteristics, Relationship Change Scales(RCS), Self-Control Scales(SCS), and Internalized Shame Scale(ISS) questionnaire. Descriptive statistical analysis was performed for the general characteristics of the study subjects, and t-test and one-way batch variance analysis (ANOVA) were used to compare interpersonal relationships according to general characteristics. The relationship between internalized shame, self-control, and interpersonal competence was analyzed by Pearson's correlation coefficient, and multiple regression analysis was performed to determine the factors affecting interpersonal relationships of stroke patients. Results : As a result of comparing interpersonal competence according to general characteristics, significant differences were found in terms of age and education level. Interpersonal relationships and internalized shame, internalized shame and self-control showed a negative correlation, and self-control and interpersonal relationships had a positive correlation, but self-control was the sub-factors of interpersonal relationships such as openness, sensitivity, intimacy, It was not statistically significant with the communication item. In addition, the items of inadequacy (β =-0.32) and adventure seeking (β =-0.23), which are sub-areas of internalized shame, affect the negative direction, and physical activity (β =0.22), which is the sub-area of self-control and the self-centered (β =0.24) item was found to have an effect on the positive direction. Conclusion : Therefore, additional research is needed that can operate a rehabilitation treatment program that applies various psychological factors for the formation of interpersonal relationships among stroke patients.

Clinical Characteristics in Panic Disorder Patients in Emergency Department (공황발작으로 응급실에 내원한 공황장애 환자들의 임상 특징)

  • Lee, Chang-Ju;Nam, Beom-Woo;Sohn, In-Ki
    • Korean Journal of Psychosomatic Medicine
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    • v.29 no.1
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    • pp.26-33
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    • 2021
  • Objectives : This study was designed to investigate datas related to panic attack and treatment in emergency room of panic disorder patients who visited emergency room for panic attack. Methods : A retrospective analysis of medical records was conducted on 92 patients with panic disorder who visited Chungju Konkuk university hospital emergency department due to panic attack and had bodily symptoms from 1st January 2010 to 31th December 2019. In addition to demographic characteristics and comorbid disorders, triggering stressors and alcohol consumption were corrected as pre-panic attack datas, bodily symptoms at the time of panic attack were corrected as datas during attack, electrocardiogram trial, consultation with psychiatrist, admission and information of used psychotropic drugs were corrected as post-attack data. Depending on size of data, Chi-square test or Fisher's exact test was used. Collected data was analyzed using R 4.03. Results : Cardiovascular disease was accompanied by 5.4% and depressive disorder was the most common coexisting mental disorder. Among triggering stressors, economic problem/work-related stress was significantly higher in men than women (𝛘2=4.322, p<0.005). The most common physical symptom during attack was circulatory (65.2%), followed by respiratory (57.6%), numbness-paralysis (33.7%), dizziness (19.6%), gastro-intestinal (14.1%) and autonomic symptom (12.0%). Electrocardiogram was taken at higher rate when patients complained circulatory symptom (𝛘2=8.46, p<0.005). The psychotropic drug most commonly used in emergency room was lorazepam, used in 92.1%. Conclusions : The most common bodily symptom during panic attack was circulatory symptom and the most common triggering stressor in men was economic problem/work-related stress. The most commonly used psychotropic for panic attack was lorazepam.

Nutritional status and metabolic syndrome risk according to the dietary pattern of adult single-person household, based on the Korea National Health and Nutrition Examination Survey (국민건강영양조사 자료에 의한 식이 패턴별 1인 가구의 영양 상태와 대사증후군 위험도)

  • Keum, Yu Been;Yu, Qi Ming;Seo, Jung-Sook
    • Journal of Nutrition and Health
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    • v.54 no.1
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    • pp.23-38
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    • 2021
  • Purpose: This study was undertaken to evaluate the health, nutritional status and metabolic syndrome risk according to the dietary pattern of adult single-person households, using information obtained from the Korea National Health and Nutrition Examination Survey (KNHANES). Methods: Data were collected from the 2013-2016 KNHANES, of adults aged 19-64 years, belonging to single-person households. Based on cluster analysis, the dietary patterns of subjects were classified into three groups. The dietary behavior factors, health-related factors, nutritional status, and prevalence of metabolic syndrome obtained from KNHANES questionnaires were compared according to the individual dietary pattern. The nutrient intake data of the subjects were calculated using the semi-food frequency questionnaire. Moreover, blood and physical measurement data of the subjects were analyzed to obtain the prevalence of metabolic syndromes. Results: The major dietary intakes of subjects were classified as 'Rice and kimchi', 'Mixed', and 'Milk·dairy products and fruits' patterns. Characteristics of subjects based on their dietary pattern, gender, age, and education level were significantly different. The 'Milk and fruits' pattern showed low frequency of skipping breakfast and eating out, and had higher intake of dietary supplements. Frequency of alcohol intake and smoking rates were highest in the 'Mixed' pattern. Maximum nutrient intake of fat, vitamin A, riboflavin, vitamin C, niacin, calcium, phosphorus, and potassium was obtained in the 'Milk·dairy products and fruits' pattern. According to dietary patterns adjusted for age and gender, the risk of metabolic syndrome was 0.380 times lower in the 'Milk·dairy products and fruit' pattern than in the 'Rice and kimchi' pattern. However, when adjusted for other confounding factors, no significant difference was obtained between dietary patterns for metabolic syndrome risk. Conclusion: These results indicate that the health and nutritional status of a single-person household is possibly affected by the dietary intake of subjects.

A Study on the Value of Dance Education through the Quality of Culture and Arts Education Service (문화예술교육 서비스 품질을 통한 무용교육의 가치에 관한 연구)

  • Lee, Sook-Young
    • Journal of Korea Entertainment Industry Association
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    • v.14 no.3
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    • pp.51-62
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    • 2020
  • The purpose of this study was to verify whether the quality of service provided by culture and arts education has a bearing on the service value of dance education, and to verify the role of the intention of reuse of culture and arts education participants in this relationship. The survey was conducted from October 1, 2019 to December 30, 2019, and a sample was collected from stratified sampling methods for the general public participating in culture and arts education. In order to verify the relationship between the independent variable and the dependent variable, multiple regression analysis was performed, and the role of the parameter in the relationship between the independent variable and the dependent variable was examined using the three-step intermediary regression analysis. The research results are as follows. First, as a result of analyzing the relationship between the sub-factors of service quality and emotional value, it was found that facilities and environmental services had the greatest impact. Second, the results of analyzing the relationship between the sub-factors of service quality and functional value showed that the most significant impact was on facilities and environmental services. Third, as a result of analyzing the relationship between the sub-factors of service quality and social values, it was found that facilities and environmental services had the greatest impact. Fourth, In the relationship between contents and instructor service and service value, the intention to reuse was found to have a full mediating effect. In addition, in the relationship between facility and environmental services and service value, the intention to reuse was found to have a partial mediating effect. Based on the quality of service of culture and arts education, this study suggested a way for dance education to work with the region.

Correlation Between Cognitive Impairment Screening Test (CIST), Korean-Mini Mental State Examination, 2nd Edition (K-MMSE~2) and Clinical Dementia Rating (CDR) of Patients with Stroke (뇌졸중 환자를 대상으로 한 인지선별검사(CIST), 한국판 간이정신상태검사 2판(K-MMSE~2) 및 임상치매척도(CDR)의 상관성)

  • Hwang, Do-Yeon;Ryu, Sung-Hyun;Kwon, Ki-Hyun;Choi, Cho-Rong;Kim, Soo-A
    • Therapeutic Science for Rehabilitation
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    • v.11 no.2
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    • pp.53-62
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    • 2022
  • Objective : This study aimed to present basic data that could help in selecting or using evaluation tools in clinical settings. Methods : This study included 51 patients with stroke. The Cognitive Impairment Screening Test (CIST), Korean-Mini Mental State Examination, 2nd Edition (K-MMSE~2), and Clinical Dementia Rating (CDR) were used as evaluation tools. The correlation between evaluation tool scores was analyzed using Spearman's rank correlation coefficient, and the comparison of total scores between the CIST and K-MMSE~2 according to global CDR scores was analyzed using the Wilcoxon signed-rank test. Results : The correlation between the total CIST and K-MMSE~2 scores and global CDR scores was statistically significant (p<.01). The correlation between the sub-scores of the CIST and K-MMSE~2 showed a statistically significant correlation for all sub-scores (p<.01). The comparison of total scores between the CIST and K-MMSE~2 according to global CDR scores showed no statistically significant differences in all global CDR scores. Conclusion : This study showed that there was a correlation between CIST, K-MMSE~2, and CDR in patients with stroke. In the future, we hope that the results of this study will help to select or use cognitive function evaluation tools in clinical settings.

Effects of Dementia Caregiver Program on Caregiver Burden (치매가족교실 프로그램이 치매 가족의 부양부담감에 미치는 효과)

  • Oh, Hye Jee;Kim, Do Hyun;Kim, Kyung Min;Lee, Jung Jae;Lee, Kyung Kyu;Lee, Seok Bum
    • Korean Journal of Psychosomatic Medicine
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    • v.29 no.2
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    • pp.184-190
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    • 2021
  • Objectives : Dementia is one of the most distressing mental health problems in the older population. Caregivers also experienced physical, psychological, and emotional stress from taking care of dementia patients. So, we developed program for supporting dementia caregiver and evaluated its efficacy on reducing caregiver burden. Methods : We provided 5 sessions of dementia caregiver supporting program to 30 caregivers who were taking care of dementia patient in their home. Program was held in Cheonan Center for Alzheimer's disease and other dementia that was established by Cheonan city government for supporting dementia patients and their caregivers. We evaluated caregiver burden using short Zarit burden inventory consisted of 12 items scoring 0 (no burden) to 4 (everyday burden) before and after program. We evaluated satisfaction of caregiver about program using satisfaction survey consisted of 10 items scoring 0 (very dissatisfy) to 4 (very satisfy) after program. Results : Mean age of caregiver was 61.9. 40.0% (n=12) of caregivers were spouse. 53.3% (n=16) of caregivers were son or daughter. Caregiver burden that was estimated by short Zarit burden inventory were significantly decreased after program (p<0.001). When each item was compared, 4 items (7, 10, 11 and 12) were significantly decreased after program (p=0.036, p=0.018, p=0.01, p=0.024). All mean scores of 10 items about satisfaction were over 3 meaning that participants generally satisfied to program. Conclusions : Our study suggested that dementia caregiver supporting program could reduce caregiver burden and provide satisfaction. Therefore, programs for supporting dementia caregivers might be important as well as treating dementia patients. So, we should be interested in developing and providing efficiently this kind of program to reduce caregiver burden.

Study on nutrition, dietary and health status of middle-aged Korean men according to sedentary hours: based on the 2019 Korea National Health and Nutrition Examination Survey (중장년 한국 남성의 좌식 시간에 따른 영양, 식이 및 건강행태 연구: 국민건강영양조사 제8기 1차년도(2019년) 자료를 이용하여)

  • Jeong, Dajeong;Lee, Jeehyun;Yoon, Eunju
    • Journal of Nutrition and Health
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    • v.55 no.3
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    • pp.359-375
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    • 2022
  • Purpose: Adult Korean men belonging to the main economically active population are known to have long sedentary hours. This study was undertaken to determine the difference and relevance of sedentary hours on the nutrition, diet, and health status of adult men, and to suggest how to prevent health risk factors. Methods: Subjects (n = 1,068) were classified into 4 groups based on their sedentary hours, ranging from the first quartile (Q1) having the least hours spent sitting, to the fourth quartile (Q4) spending the longest hours. Results: Subjects belonging to Q4 had the lowest average age, the largest waist circumference, and the highest level of education. Among those engaged in economic activities, the ratio of white-collar workers was significantly higher in Q4. Accordingly, the rate of not doing high-intensity or moderate-intensity physical activity while working was also the highest in Q4. A significant difference was obtained in the drinking frequency between groups, but this was found to be associated with the average working hours rather than sedentary hours. The proportion of not doing aerobic exercise was higher with longer sitting hours. The highest diagnosis of diabetes (8.8%) was obtained in the Q4 group. Among the factors related to cardiovascular disease, only low density lipoprotein-cholesterol showed a significant difference, with Q4 being significantly higher than Q1. Considering energy and nutrient intake, vitamin B1 and calcium intake were the lowest in the group with the longest sitting hours, as well as the least consumption of vitamin C than the recommended estimated average requirement. Conclusion: The results of this study suggest that the health and nutritional status of Korean adult men are affected by sedentary hours. This should be recognized as a health risk factor and guidelines need to be developed for sedentary lifestyle management.