• Journal of Biomedical Engineering Research
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• v.29 no.1
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• pp.73-81
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• 2008

The purpose of this study is to observe the brain activity patterns during visual oddball tasks with two difficulty levels by the analysis of high-density event-related potential (ERP). Along with conventional statistical analysis of averaged ERP waveforms, we applied independent component analysis (ICA) for the individual, single-trial analysis and verified its effectiveness. We could identify multiple ERP components such as early visual components (P1, N1), and two components which seem to be important task-related components and showed difficulty-dependent variability (P2, P300). The P2 was found around central region at $180{\sim}220ms$, and the P300 was found globally at $300{\sim}500ms$ poststimulus. As the task became difficult, the P2 amplitude increased, and the P300 amplitude decreased. After single-trial ERPs were decomposed into multiple independent components (ICs), several ICs resulting from P2 and P300 sources were identified. These ICs were projected onto scalp electrodes and the projected ICs were statistically compared according to two task difficulties. For most subjects, the results obtained from single-trial/individual analysis using ICA gave the tendencies of amplitude change that are similar to the averaged ERP analysis for most subjects. The temporal pattern and number of ICs corresponding to ${\mu}$ rhythm was not dependent on the task difficulty. It seems that the motor response was not affected by the task difficulty.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.2
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• pp.176-186
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• 1996

The fit of a respirator to the face of an individual can be determined by a qualitative fit test (QLFT) or a quantitative fit test (QNFT). The pass/fail decision from a QLFT or QNFT for the same respirator on the same individual may vary from one wearing to the next, because the human facial features are complex and the respirator may not fit to the face in the same way every time it is worn. This study reports how the fit factors (FF) resulting from a QNFT on an individual vary from day to day and depend on the movements in the six fit test exercises. The reported FFs provide an objective and numerical basis (FF) which does not depend on the subject's voluntary or involuntary response. Four half-mask (H1-H4) and four full-facepiece respirators (F1-F4) were fit tested on one wearer 10 times a day for 5 days with a PortaCount (model 8010, TSI). The FFs obtained for each set of 10 fit tests on a specific day and 50 fit tests on five days involving one of the six exercise regimes have been recorded as log-normal distributions. All of the geometric standard deviations (GSD) of the overall FFs varied widely among every wearing and day except for H1 and F3, and the variability of the half-mask respirators was larger than that of the full-facepiece respirators. Among the six exercise regimes, reading or talking (RT) had markedly the lowest exercise FFs on the tested individual. Generally, there were significant differences between the first normal breathing (NB1) FFs and the remaining exercise FFs.

• Journal of Preventive Medicine and Public Health
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• v.43 no.3
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• pp.265-273
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• 2010

Objectives: Due to the economic crisis and globalization, many workers have been suffering from severe occupational stress due to job insecurity and struggles related to downsizing and restructuring. This study aims to assess the stress levels among workers involved in fierce labor disputes and massive layoffs and to evaluate their specific needs and satisfaction with counseling services set up to help workers cope with severely stressful situations? Methods: The authors provided crisis intervention to workers in traumatic situations to compare the differential level of stress responses and needs among the workers remaining employed in a large auto factory, those laid off by it, and those laid off by other companies in the same region (Pyeongtaek, Gyeonggi Province). We measured stress levels using the worker's stress response inventory (WSRI) and heart rate variability (HRV), and assessed workers' satisfaction with the counseling services. Results: 502 workers participated in the program. Fifty-seven percent of them consulted with occupational problems. The mean WSRI score of the workers remaining employed in the automobile factory was higher than that of the unemployed (employed: $39.8{\pm}19.9$ unemployed: $29.3{\pm}18.8$). Ninety-five percent of workers responded that they were satisfied or very satisfied with the counseling services. Conclusions: This study suggests the urgent need for the establishment of a national crisis intervention program dedicated to supporting workers in severely stressful situations.

• Safety and Health at Work
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• v.5 no.4
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• pp.210-215
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• 2014

Background: The ongoing economic crisis in Greece has affected both stress and quality of life (QoL) at all socioeconomic levels, including professionals in the police force. The aim of this study was to examine perceived stress, job satisfaction, QoL, and their relationships in a sample of police officers in Greece. Methods: A cross-sectional study was conducted during the first trimester of 2011 in 23 police stations in the greater Athens area. A total of 201 police officers agreed to participate (response rate 44.6%). The General Health Questionnaire-28 (GHQ-28) was used to assess general health, and the World Health Organization Quality of Life-BREF Questionnaire and Perceived Stress Scale-14 (PSS-14) questionnaires were used to assess QoL and perceived stress, respectively. Results: The PSS and GHQ subscales and total scores exhibited strong, positive, and significant correlations coefficients (r): 0.52 for somatic disturbances, 0.56 for stress and insomnia, 0.40 for social dysfunction, and 0.37 for depression, yielding an r equal to 0.57 for the total GHQ score. A higher level of perceived stress was related to a lower likelihood of being satisfied with their job; in this regard, male participants and higher ranked officers reported lower job satisfaction. The PSS and GHQ scores were inversely, consistently, and significantly related to almost all of the QoL aspects, explaining up to 34% of their variability. Parenthood had a positive effect on QoL related to physical health, and women reported lower QoL related to psychological health. Conclusion: Higher levels of stress are related to an increased risk of reporting suboptimal job satisfaction and QoL. The magnitude of these associations varied depending on age, gender, and rank, highlighting the need for stress-management training.

• Journal of Korean Academy of Nursing
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• v.49 no.4
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• pp.361-374
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• 2019

Purpose: This study was conducted to evaluate the effectiveness of autogenic training on stress responses through a systematic review and meta-analysis. Methods: A systematic search was conducted using eight core electronic databases (Embase, CENTRAL, Medline, CINAHL, PsycInfo, DBpia, KISS, and RISS). To estimate the effect size, a meta-analysis of the studies was performed using RevMan 5.3.5 program. Results: A total 21 studies out of 950 studies were included in the review, and 11 were included for meta-analysis. These studies showed that autogenic training decreased anxiety and depression, and increased the high frequency of heart rate variability. Calculations to understand the effect of autogenic training on anxiety, through a meta-analysis, observed a reduction effect of anxiety score by 1.37 points (n=85, SMD=-1.37: 95% CI -2.07 to -0.67), in the studies on short-term intervention targeting healthy adults. On the other hand, similar calculations to understand the effect of autogenic training on depression observed, a reduction effect on the depression score by 0.29 point (n=327, SMD=-0.29: 95% CI -0.50 to -0.07), in the studies on long term intervention targeting the patient group. Conclusion: Autogenic training is effective for adults' stress management, and nurses will be able to effectively perform autogenic training programs for workers' stress relief at the workplace.

• Ocean and Polar Research
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• v.44 no.3
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• pp.221-233
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• 2022

A sediment trap had been deployed at 1250 m depth in the Eastern Tropical Pacific (ETP) from September 2009 to July 2010, with the aim of understanding the temporal and vertical variability of particle flux. During the monitoring period, total particle flux varied from 12.4 to 101.0 mg m^-2day^-1, with the higher fluxes in January-March 2010. Biogenic particle flux varied in phase with the total particle flux. The increase in total particle flux during January-March 2010 was attributed to the enhanced biological production in the surface layer caused by wind-driven mixing in response to the seasonal shifts in the location of the Intertropical convergence zone. The export ratio (e-ratio) was estimated using the particulate organic carbon flux and satellite-derived net primary production data. The estimated e-ratios changed between 0.8% and 2.8% (1.4±0.6% on average). The ratio recorded in the negative phase of Pacific decadal oscillation (PDO) was similar to the previous results obtained from the ETP during the 1992/93 periods in the positive phase of PDO. This suggests that the regime shift of the PDO is not related to the carbon export ratio.

• Journal of People, Plants, and Environment
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• v.24 no.5
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• pp.545-550
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• 2021

Background and objective: With increasing land use intensity in urban areas, apartment buildings have been recognized as a typical type of urban residence. In this study, the impacts of different views through a window on health-related responses were investigated using psychological and physiological parameters. Methods: Photos of three different types of views taken on low (2-12 m), middle (28-35 m), and high (over 54 m) floors of dense apartment building areas were used as visual stimuli. Twenty-two healthy adults participated in the indoor experiment. Semantic differential methods and profile of mood states were used as psychological tools. Autonomic nervous activity was evaluated using blood pressures, pulse rate and heart rate variability (HRV). Results: Analytic data showed different characteristics of psychological and physiological outcomes in three different apartment views. In the analysis of psychological parameters, significantly negative responses to the views on middle floors were found in the subscales of tension-anxiety and anger-hostility, compared to low floors. Significantly positive scores in the subscale of vigor were found on low floors with abundance of vegetation and high floors with a view of the sky. A significantly increased value of HF was found on low floors (2,294.96 ± 169.79), compared to the middle(1,553.45 ± 84.66) and high (1,523.02 ± 70.49) floors. Despite the high scores in openness and vigor, high floor views showed significantly higher LF/HF values (1.83 ± 0.09), the indicator of the sympathetic nervous system, than low (1.30 ± 0.07) and middle floor views (1.34 ± 0.06), which might be related to the unconscious fear of heights. Conclusion: Views from different heights in an apartment building can affect the psychological states of residents. Green space through the window may have a positive health outcome by reducing physiological stress.

• Journal of People, Plants, and Environment
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• v.24 no.1
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• pp.107-117
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• 2021

Background and objective: The purpose of this study is to investigate the effect of a forest healing program in terms of depression, neuropsychological and physiological benefits for the elderly. Methods: For this purpose, we developed a forest therapy program for the elderly who are vulnerable to dementia and conducted a total of 11 sessions of forest therapy activities in a forest once a week. We measured the changes in depression, resting-state Electroencephalography(EEG) and heart rate variability (HRV) before and after the program. There were 60 subjects aged over 65 yesrs old. 30 subjects participated in the forest therapy program, and the other were in the control group. The Geriatric Depression Scale was used to measure the level of depression, neuroNicle FX2 (Laxtha, Korea) was used to measure the resting-state EEG, and photoplethymogram (ubpulse T1, Laxtha, Korea) was used to measure the HRV. Results: The results showed that the depression index of the experimental group improved with statistical significance after the program (experiment group = 3.267 decrease of the mean). In the EEG measurement, the alpha-peak frequency at rest (experimental group = 0.227 Hz increase of the mean) was improved (mean increase = 0.23 in the experimental group, p < .05). The high frequency of HRV, which represents the parasympathetic nerve activity of the body's autonomous response, was also significantly improved (mean increase = 0.396 in the experimental group, p < .05). Conclusion: The results suggest that the forest therapy program can reduce the cognitive, psychological and physical risk factors of dementia for the elderly at risk of cognitive decline. Therefore, forest therapy activities may be suitable for the prevention of dementia in the elderly.

• Earthquakes and Structures
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• v.23 no.1
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• pp.35-57
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• 2022

This article presents a computationally efficient framework for multi-objective seismic design optimization of steel moment-resisting frame (MRF) structures based on the nonlinear dynamic analysis procedure. This framework employs the uniform damage distribution philosophy to minimize the weight (initial cost) of the structure at different levels of damage. The preliminary framework was recently proposed by the authors based on the single excitation and the nonlinear static (pushover) analysis procedure, in which the effects of record-to-record variability as well as higher-order vibration modes were neglected. The present study investigates the reliability of the previous framework by extending the proposed algorithm using the nonlinear dynamic design procedure (optimization under multiple ground motions). Three benchmark structures, including 4-, 8-, and 12-story steel MRFs, representing the behavior of low-, mid-, and high-rise buildings, are utilized to evaluate the proposed framework. The total weight of the structure and the maximum inter-story drift ratio (IDRmax) resulting from the average response of the structure to a set of seven ground motion records are considered as two conflicting objectives for the optimization problem and are simultaneously minimized. The results of this study indicate that the optimization under several ground motions leads to almost similar outcomes in terms of optimization objectives to those are obtained from optimization under pushover analysis. However, investigation of optimal designs under a suite of 22 earthquake records reveals that the damage distribution in buildings designed by the nonlinear dynamic-based procedure is closer to the uniform distribution (desired target during the optimization process) compared to those designed according to the pushover procedure.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.7 no.1
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• pp.79-84
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• 1969

Protein content of Korean native and currently recommended varieties varied from 5.3% to 9.4%. Higher protein content was shown in Indicas than Japonicas and generally in the earlier varieties than in the latter ones. Additional application of nitrogen significantly increased the protein content, and varietal difference in this response was noticed. Delayed harvesting reduced protein content and denser planting induced higher protein content in the brown rice.