• Journal of Society of Preventive Korean Medicine
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• v.19 no.3
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• pp.1-10
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• 2015

Objectives : The purpose of this study was to reveal the prevalence of Mibyeong and its symptoms including fatigue, pain, sleep disturbance, dyspepsia, depression, anxiety and anger by using the national survey. Methods : Questionnaires were collected by Gallup Korea. Participants were chosen through stratified sampling method based on area, gender and age. Questionnaire was designated to confirm the recognition, managing of Mibyeong, investigation of life habit, medical history, basic information, QoL questionnaires (Short Form-12, EuroQol-5D) and understanding of Mibyeong medical service conditions. Generally all questionnaires were used for survey the Mibyeong status in public except QoL questionnaires. Questionnaires were fulfilled by professional surveyor as face to face interview. Descriptives was used for data analysis and the results were expressed as percentage ratios (%) Results : 1,101 of people were acquired in this study. Eighty point two (80.2%) percent of participants did not know the concept of Mibyeong accurately even though 80.6% complained of Mibyeong related symptoms. Among them, fatigue was accounted for the highest response (70.7%)in this study. Sixty point four percent of participants identified non-smoking, stop drinking, eating habits and sleeping habits as a way to manage their Mibyeong related symptoms. In addition, exercising (60.8%), visiting medical institution (58.4%) and taking health functional food (52.7%) were presented. Only 23.1% among people with symptoms Mibyeong visited medical facilities. Moreover, the quality of life was found to be significantly correlated with health status. Conclusions : This study could contribute to express the importance of announcing the concept of Mibyeong and status to Korean public. Moreover, more Mibyeong studies should be conducted in the future to evaluate the Mibyeong status objectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.281-287
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• 2005

Nonlinear behaviors such as steep-fronted wave motions and a finite amplitude limit cycle often accompanying combustion instabilities have been numerically investigated using a characteristic-based approximate Riemann solver and the well-known ${\eta}-{\tau}$ model. A resonant pipe initially subjected to a harmonic pressure disturbance described the natural steepening process that leads to a shocked N-wave. For a linearly unstable regime, pressure oscillations reach a limit cycle which is independent of the characteristics of the initial disturbances and depends only on combustion parameters and operating conditions. For the 1.5 MW gas generator under development in KARI, the numerical results show good agreement with experimental data from hot-firing tests.

• Journal of Korean Public Health Nursing
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• v.29 no.1
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• pp.102-114
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• 2015

Purpose: This study was conducted in order to identify consumption status, risk awareness and experience of adverse effects of high caffeine energy drink among university students. Methods: This study was a descriptive survey including 270 students in 2 universities and 7 colleges in D metropolitan city. Consumption Status, Risk Awareness and Experience of Adverse Effects of High-Caffeine Energy Drink tools were developed by literature review. Data analyzed using descriptive statistics and $x^2$-test. Results: In the results, 86.7% of the students had previous experience of energy drink consumption and male students and smokers had more experience of energy drink consumption than female students and nonsmokers. The reason of energy drink consumption was increasing alertness for studying. 45.7% of the students were aware of the risk of high caffeine energy drink and the first risk was sleep disturbance. 51.1% of students were experienced adverse effects, mainly palpitation and sleeplessness. Conclusion: The results suggest a need to increase awareness of adverse effects and potential risks of high caffeine energy drink consumption in university students. In addition, university and government should provide education and campaigns to prevent excessive high caffeine energy drink consumption.

• Physical Therapy Korea
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• v.23 no.1
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• pp.38-45
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• 2016

Background: Chronic back pain shows a high correlation with lumbar disability, physical disability for daily activities, and psychosocial factors, such as depression. Object: The purpose of this study was to examine the correlation of the level of pain and disability with psychosocial factors, which are potential disturbance variables, in patients with chronic lumbar pain. Method: The sample included 258 patients, who had complained of chronic lumbar pain for more than three months. The Quadruple Visual Analogue Scale was used to measure the level of pain, and a Korean version of Oswestry Disability Index was used to measure the level of disability. Psychosocial factors were measured using the Tampa scale for Kinesiophobia-11, Fear Avoidance Beliefs Questionnaire, and Pain Self-Efficacy Questionnaire. The collected data was analyzed using PASW 18.0, and an independent samples t-test was used to examine frequency, percentage, mean, and standard deviation of sociodemographic characteristics and major variables. Pearson's correlation coefficient was used to investigate the correlation between the level of pain and disability and psychosocial factors. Stepwise multiple regression analysis was done to determine the level of pain and psychosocial factors of functional disorder. The significance level was set at ${\alpha}=.05$. Result: There is a strong correlation between the level of pain and functional disorder and psychosocial factors in patients with chronic lumbar pain. The study also revealed that as the levels of pain and fear avoidance increase, pain self-efficacy decreases. Conclusion: The results suggest that negative perceptions towards pain, limitations of physical movement, and severe fear avoidance directly affect the decrease in pain self-efficacy. Therefore, it is recommended to test pain self-efficacy when measuring the level of pain and disability in patients with chronic low back pain.

• Bulletin of the Korean Space Science Society
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• 2011.04a
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• pp.26.3-27
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• 2011

Formation of a steep plasma density gradient in the middle-latitude ionosphere during geomagnetic storms and the latitudinal migration of its location depending on the storm phase are suggested to be associated with the ionospheric signature of the plasmapause. We test this idea by using the satellite and ground observation data during the 11 April 2001 storm. The locations of the steep plasma density gradient identified by TOPEX/Poseidon (2001 LT) and DMSP (1800 and 2130 LT) satellites coincide with the ionospheric footprints of the plasmapause identified by the IMAGE satellite. This observation may support the dependence of the middle-latitude plasma density gradient location on the plasmapause motion, but does not explain why the steep density gradient whose morphology is largely different from the morphology of the middle-latitude ionization trough during quiet period is formed in association with the plasmapause. The ionospheric disturbances in the total electron content (TEC) maps shows that the steep TEC gradient is formed at the boundary of the positive ionospheric storm in low-middle latitudes and the negative ionospheric storm in middle-high latitudes. We interpret that the thermospheric neutral composition disturbance in the dayside is confined within the middle-high latitude ionospheric convection zone. The neutral composition latitudes and, therefore, the locations of the steep plasma density gradient coincide with the footprints of the plasmapause. The TEC maps show that the appearance of the steep plasma density gradient in the pre-midnight sector during the recovery phase is related to the co-rotation of the gradient that is created during the main phase.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.162-177
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• 2020

Background: Ecologists have achieved much progress in the study of mechanisms that maintain species coexistence and diversity. In this paper, we reviewed a wide range of past research related to these topics, focusing on five theoretical bodies: (1) coexistence by niche differentiation, (2) coexistence without niche differentiation, (3) coexistence along environmental stress gradients, (4) coexistence under non-equilibrium versus equilibrium conditions, and (5) modern perspectives. Results: From the review, we identified that there are few models that can be generally and confidently applicable to different ecological systems. This problem arises mainly because most theories have not been substantiated by enough empirical research based on field data to test various coexistence hypotheses at different spatial scales. We also found that little is still known about the mechanisms of species coexistence under harsh environmental conditions. This is because most previous models treat disturbance as a key factor shaping community structure, but they do not explicitly deal with stressful systems with non-lethal conditions. We evaluated the mainstream ideas of niche differentiation and stochasticity for the coexistence of plant species across salt marsh creeks in southwestern Denmark. The results showed that diversity indices, such as Shannon-Wiener diversity, richness, and evenness, decreased with increasing surface elevation and increased with increasing niche overlap and niche breadth. The two niche parameters linearly decreased with increasing elevation. These findings imply a substantial influence of an equalizing mechanism that reduces differences in relative fitness among species in the highly stressful environments of the marsh. We propose that species evenness increases under very harsh conditions if the associated stress is not lethal. Finally, we present a conceptual model of patterns related to the level of environmental stress and niche characteristics along a microhabitat gradient (i.e., surface elevation). Conclusions: The ecology of stressful systems with non-lethal conditions will be increasingly important as ongoing global-scale climate change extends the period of chronic stresses that are not necessarily fatal to inhabiting plants. We recommend that more ecologists continue this line of research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2092-2099
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• 2013

Through the data transfer race in industry since 1990s, the operational speed of optical disk drive(ODD) becomes commonly over 10,000 rpm. Such high speed operation inevitably causes the vibration, which is also the disturbances in the read-write process of pick-up servo-controller. Generally the vibration disturbance problem can be solved by the vibration isolation using the rubber mount and the increase of robustness of the pick-up servo-controller. Optical disk itself has not been targeted for the vibration reduction, because it is manufactured under the standardized format. In this paper we focused on the increase of critical speed of optical disk, that is, the improvement of dynamic characteristics, with the control of residual stresses which are come from the injection molding process. To do this, first, the residual stresses induced from the injection molding process are calculated using finite element method. The major design parameters of the process conditions are flow rate and melt temperature, which control the residual stresses in optical disk. Second, the critical speed of optical disk is calculated with modal analysis considering residual stress distributions. It was found out that the critical speed can be improved by the control of operational parameters in the injection molding process.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.6
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• pp.524-530
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• 2002

A control of the body posture and movement is maintained by the vestibular system, vision, and proprioceptors. Afferent signals from those receptors are transmitted to the vestibular nuclear complex, and the efferent signals from the vestibular nuclear complex control the eye movement and skeletal muscle contract. The postural disturbance caused by loss of the vestibular function results in nausea, vomiting, vertigo and loss of craving for life. The purpose of this study is to develop a off-vertical rotatory system for evaluating the function of semicircular canals and otolith organs, selectively, and visual stimulation system for- stimulation with horizontal, vortical and 3D patterns. The Off-vortical axis rotator is composed of a comportable chair, a DC servo-motor with reducer and a tilting table controlled by PMSM. And a double feedback loop system containing a velocity feedback loop and a position feedback loop is applied to the servo controlled rotatory chair system. Horizontal, vertical, and 3D patterns of the visual stimulation for applying head mounted display are developed. And wireless portable systems for optokinetic stimulation and recording system of the eye movement is also constructed. The gain, phase, and symmetry is obtained from analysis of the eye movement induced by vestibular and visual stimulation. Detailed data were described.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.6
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• pp.546-553
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• 2002

A control of the body posture and movement is maintained by the vestibular system, vision, and proprioceptors. Especially, vestibular system has a very important function that controls the eye movement through vestibuloocular reflex and contraction of skeletal muscles through vestibulospinal reflex. However, postural disturbance caused by loss of vestibular function results in nausea, vomiting, vertigo and loss of craving for life. Lose of vestibular function leads to abnormal reflex of eye movements named nystagmus. Analysis of the nystagmus is needed to diagnose the vertigo, which is performed by means of electrooculography(EOG). The purpose of this study is to develop a computerized system for data processing and an algorithm for the automatic evaluation of the slow component velocity(SCV) of nystagmus induced by optokinetic(OKN) stimulation system. A new algorithm using recursive least square method(RLSM) to detect SCV of nystagmus is suggested in this paper. This method allows a fast and precise evaluation of the nystagmus, through artifact rejection techniques. The results are depicted in this paper.

• The Journal of Internal Korean Medicine
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• v.26 no.2
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• pp.475-481
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• 2005

Objectives: This study was designed to evaluate the effects of an oriental medicine therapy, namely Bojoongikkitang-gamibang, on a chronic cystitis patient. Methods: The clinical data was analyzed on a patient with chronic cystitis due to Bigiheoyak(脾氣虛弱) and Junggihaham(中氣下陷) whose main symptoms were urinary disturbances, such as urgency, weak stream, hesitancy and nocturia, etc. The patient visited twice at the internal medicine department of Dae-Gu Hanny University Dae-Gu Oriental Medicine Hospital on May 20, and on June 3, 2004 and was only treated with herbal medicine(Bojoongikkitang-gamibang). Results: After treatment, improvement was seen in the subsection of the International Prostate Symptom Score(IPSS). Conclusions: This study suggests that Bojoongikkitang-gamibang is significantly effective in treatment of a chronic cystitis.