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Search Results: 1 - 10 of 27478 matches for " Jong-Ho Kim "
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The Impacts of Physical Exercise on Stress Coping and Well-Being in University Students in the Context of Leisure  [PDF]
Jong-Ho Kim, Larry A. McKenzie
Health (Health) , 2014, DOI: 10.4236/health.2014.619296
Abstract: This study aims at investigating the in-depth information regarding impacts of physical exercise on psychological well-being in university students with an emphasis on coping with stress in the context of leisure. A qualitative research, based on interview to draw findings in an inductive way, was conducted. Nine university students (N = 9) in a large mid-west university took part in a face- to face, semi-structured interviews using ten open-ended questions with respect to benefits of leisure time physical exercise. The interview on the basis of phenomenological research examined what the participants experienced with leisure time physical exercise in conjunction with stress coping and mental health. Meaningful units of themes were induced with 24 initially drawn themes. These themes were reduced to 8 comprehensive constituent themes: self-efficacy, positive emotion, mind and body, health-behaviors, self-esteem, leisure, problem-focused coping, and positive expectancy. These reduced themes were finally boiled down to 6 integrated themes: positive emotion, unity of mind and body, heightened self-esteem, leisure, problem-focused coping, and self-regulation of health behavior. This research may shed a light in illuminating potential mechanism of how regular physical exercise is conducive to enhanced health behavior as well as effective stress coping in university students in the context of leisure. In particular, this research appears to be meaningful in suggesting that regular leisure-time physical exercise can lead to an effective problem-focused coping through elicitation of positive emotion.
A New Weighted Correlation Coefficient Method to Evaluate Reconstructed Brain Electrical Sources
Jong-Ho Choi,Min-Hyuk Kim,Luan Feng,Chany Lee,Hyun-Kyo Jung
Journal of Applied Mathematics , 2012, DOI: 10.1155/2012/251295
Abstract: Various inverse algorithms have been proposed to estimate brain electrical activities with magnetoencephalography (MEG) and electroencephalography (EEG). To validate and compare the performances of inverse algorithms, many researchers have used artificially constructed EEG and MEG datasets. When the artificial sources are reconstructed on the cortical surface, accuracy of the source estimates has been difficult to evaluate. In this paper, we suggest a new measure to evaluate the reconstructed EEG/MEG cortical sources more accurately. To validate the usefulness of the proposed method, comparison between conventional and proposed evaluation metrics was conducted using artificial cortical sources simulated under different noise conditions. The simulation results demonstrated that only the proposed method could reflect the source space geometry regardless of the number of source peaks.
Hypertensive brainstem encephalopathy involving deep supratentorial regions: does only blood pressure matter?
Jong-Ho Park,Sung-Min Kim,Hyung-Woo Shin,Sang Joon An
Neurology International , 2010, DOI: 10.4081/ni.2010.e9
Abstract: We report on a 42-year-old female patient who presented with high arterial blood pressure of 245/150 mmHg and hypertensive brainstem encephalopathy that involved the brainstem and extensive supratentorial deep gray and white matter. The lesions were nearly completely resolved several days after stabilization of the arterial blood pressure. Normal diffusion-weighted imaging findings and high apparent diffusion coefficient values suggested that the main pathomechanism was vasogenic edema owing to severe hypertension. On the basis of a literature review, the absolute value of blood pressure or whether the patient can control his/her blood pressure seems not to be associated with the degree of the lesions evident on magnetic resonance imaging. It remains to be determined if the acceleration rate and the duration of elevated arterial blood pressure might play a key role in the development of the hypertensive encephalopathy pattern.
Diffuse Extraplanar Dust in NGC 891
Kwang-Il Seon,Adolf N. Witt,Jong-Ho Shinn,Il-Joong Kim
Physics , 2014, DOI: 10.1088/2041-8205/785/1/L18
Abstract: We report the detection of vertically extended far-ultraviolet (FUV) and near-UV emissions in an edge-on spiral galaxy NGC 891, which we interpret as being due to dust-scattered starlight. Three-dimensional radiative transfer models are used to investigate the content of the extraplanar dust that is required to explain the UV emission. The UV halos are well reproduced by a radiative transfer model with two exponential dust disks, one with a scaleheight of $\approx$ 0.2 - 0.25 kpc and the other with a scaleheight of $\approx$ 1.2 - 2.0 kpc. The central face-on optical depth of the geometrically thick disk is found to be $\tau_{thick} \approx$ 0.3 - 0.5 at B-band. The results indicate that the dust mass at |z| > 2 kpc is $\approx$ 3 - 5% of the total dust mass, which accord well with the recent Herschel sub-millimeter observation. Our results, together with the recent discovery of the UV halos in other edge-on galaxies, suggest the widespread existence of the geometrically thick dust layer above the galactic plane in spirals.
Increased Mesohippocampal Dopaminergic Activity and Improved Depression-Like Behaviors in Maternally Separated Rats Following Repeated Fasting/Refeeding Cycles
Jeong Won Jahng,Sang Bae Yoo,Jin Young Kim,Bom-Taeck Kim,Jong-Ho Lee
Journal of Obesity , 2012, DOI: 10.1155/2012/497101
Abstract: We have previously reported that rats that experienced 3 h of daily maternal separation during the first 2 weeks of birth (MS) showed binge-like eating behaviors with increased activity of the hypothalamic-pituitary-adrenal axis when they were subjected to fasting/refeeding cycles repeatedly. In this study, we have examined the psychoemotional behaviors of MS rats on the fasting/refeeding cycles, together with their brain dopamine levels. Fasting/refeeding cycles normalized the ambulatory activity of MS rats, which was decreased by MS experience. Depression-like behaviors, but not anxiety, by MS experience were improved after fasting/refeeding cycles. Fasting/refeeding cycles did not significantly affect the behavioral scores of nonhandled (NH) control rats. Fasting/refeeding cycles increased dopamine levels not only in the hippocampus but also in the midbrain dopaminergic neurons in MS rats, but not in NH controls. Results demonstrate that fasting/refeeding cycles increase the mesohippocampal dopaminergic activity and improve depression-like behaviors in rats that experienced MS. Together with our previous paper, it is suggested that increased dopamine neurotransmission in the hippocampus may be implicated in the underlying mechanisms by which the fasting/refeeding cycles induce binge-like eating and improve depression-like behaviors in MS rats.
Increased Mesohippocampal Dopaminergic Activity and Improved Depression-Like Behaviors in Maternally Separated Rats Following Repeated Fasting/Refeeding Cycles
Jeong Won Jahng,Sang Bae Yoo,Jin Young Kim,Bom-Taeck Kim,Jong-Ho Lee
Journal of Obesity , 2012, DOI: 10.1155/2012/497101
Abstract: We have previously reported that rats that experienced 3?h of daily maternal separation during the first 2 weeks of birth (MS) showed binge-like eating behaviors with increased activity of the hypothalamic-pituitary-adrenal axis when they were subjected to fasting/refeeding cycles repeatedly. In this study, we have examined the psychoemotional behaviors of MS rats on the fasting/refeeding cycles, together with their brain dopamine levels. Fasting/refeeding cycles normalized the ambulatory activity of MS rats, which was decreased by MS experience. Depression-like behaviors, but not anxiety, by MS experience were improved after fasting/refeeding cycles. Fasting/refeeding cycles did not significantly affect the behavioral scores of nonhandled (NH) control rats. Fasting/refeeding cycles increased dopamine levels not only in the hippocampus but also in the midbrain dopaminergic neurons in MS rats, but not in NH controls. Results demonstrate that fasting/refeeding cycles increase the mesohippocampal dopaminergic activity and improve depression-like behaviors in rats that experienced MS. Together with our previous paper, it is suggested that increased dopamine neurotransmission in the hippocampus may be implicated in the underlying mechanisms by which the fasting/refeeding cycles induce binge-like eating and improve depression-like behaviors in MS rats. 1. Introduction Neonatal maternal separation is considered as an animal model of stressful experience early in life. A number of studies have demonstrated that neonatal maternal separation may lead to permanent alterations in the characteristics of the hypothalamic-pituitary-adrenal (HPA) axis responding to stress [1–3] and the development of depression- [4, 5] and anxiety-like behaviors [6, 7] later in life. We have previously demonstrated that rats experienced 3?h of daily maternal separation during the first 2 weeks of birth (MS) exhibit depression- and anxiety-like behaviors [8, 9] with altered response of the HPA axis to stress challenges later in life [10, 11]. Dysfunction of the HPA axis is implicated in the pathogenesis of eating disorders [12–14], and symptoms of anxiety and depression are associated with the pathophysiology of eating disorders [15, see for review], especially with binge-like eating disorders [16, 17]. Our MS rats showed binge-like eating behavior when they were challenged with repeated fasting/refeeding cycles during adolescent period, and their binge-like eating behavior appeared to be related with increased activity of the HPA axis [11]. The dopaminergic system has been of
PAGaN I: Multi-Frequency Polarimetry of AGN Jets with KVN
Jae-Young Kim,Sascha Trippe,Bong Won Sohn,Junghwan Oh,Jong-Ho Park,Sang-Sung Lee,Taeseok Lee,Daewon Kim
Physics , 2015, DOI: 10.5303/JKAS.2015.48.5.285
Abstract: Active Galactic Nuclei (AGN) with bright radio jets offer the opportunity to study the structure of and physical conditions in relativistic outflows. For such studies, multi-frequency polarimetric very long baseline interferometric (VLBI) observations are important as they directly probe particle densities, magnetic field geometries, and several other parameters. We present results from first-epoch data obtained by the Korean VLBI Network (KVN) within the frame of the Plasma Physics of Active Galactic Nuclei (PAGaN) project. We observed seven radio-bright nearby AGN at frequencies of 22, 43, 86, and 129 GHz in dual polarization mode. Our observations constrain apparent brightness temperatures of jet components and radio cores in our sample to $>10^{8.01}$ K and $>10^{9.86}$ K, respectively. Degrees of linear polarization $m_{L}$ are relatively low overall: less than 10%. This indicates suppression of polarization by strong turbulence in the jets. We found an exceptionally high degree of polarization in a jet component of BL Lac at 43 GHz, with $m_{L} \sim$ 40%. Assuming a transverse shock front propagating downstream along the jet, the shock front being almost parallel to the line of sight can explain the high degree of polarization.
PAGaN II: The Evolution of AGN Jets on Sub-Parsec Scales
Junghwan Oh,Sascha Trippe,Sincheol Kang,Jae-Young Kim,Jong-Ho Park,Taeseok Lee,Daewon Kim,Motoki Kino,Sang-Sung Lee,Bong Won Sohn
Physics , 2015, DOI: 10.5303/JKAS.2015.48.5.299
Abstract: We report first results from KVN and VERA Array (KaVA) VLBI observations obtained in the frame of our Plasma-physics of Active Galactic Nuclei (PAGaN) project. We observed eight selected AGN at 22 and 43 GHz in single polarization (LCP) between March 2014 and April 2015. Each source was observed for 6 to 8 hours per observing run to maximize the $uv$ coverage. We obtained a total of 15 deep high-resolution images permitting the identification of individual circular Gaussian jet components and three spectral index maps of BL Lac, 3C 111 and 3C 345 from simultaneous dual-frequency observations. The spectral index maps show trends in agreement with general expectations -- flat core and steep jets -- while the actual value of the spectral index for jets shows indications for a dependence on AGN type. We analyzed the kinematics of jet components of BL Lac and 3C 111, detecting superluminal proper motions with maximum apparent speeds of about $5c$. This constrains the lower limits of the intrinsic component velocities to $\sim0.98c$ and the upper limits of the angle between jet and line of sight to $\sim$20$\deg$. In agreement with global jet expansion, jet components show systematically larger diameters $d$ at larger core distances $r$, following the global relation $d\approx0.2r$, albeit within substantial scatter.
Comparison of the Diffuse Halpha and FUV Continuum Backgrounds: On the Origins of the Diffuse Halpha Background
Kwang-Il Seon,Adolf Witt,Il-Joong Kim,Jong-Ho Shinn,Jerry Edelstein,Kyoung-Wook Min,Wonyong Han
Physics , 2011, DOI: 10.1088/0004-637X/743/2/188
Abstract: We compare the diffuse H$\alpha$ map of our Galaxy with the FUV (1370-1710\AA) continuum map. The H$\alpha$ intensity correlates well with the FUV intensity. The H$\alpha$/FUV intensity ratio increases in general with the H$\alpha$ intensity and the FUV hardness ratio (1370-1520\AA\ to 1560-1710\AA), implying that late OB stars may be the main source of the H$\alpha$ recombination line at high latitudes. The variation of the H$\alpha$ intensity as a function of the Galactic latitude is also very similar to that of the FUV intensity. The results likely suggest that not only the original radiation sources of the H$\alpha$ and FUV backgrounds but also the radiative transfer mechanisms responsible for the diffuse backgrounds are largely common. Therefore, we propose a scenario wherein the H$\alpha$ background at high latitudes is mostly composed of two components, H$\alpha$ photons produced by in-situ recombination at the ionized regions around late OB stars and dust-scattered light of the H$\alpha$ photons originating from late OB stars.
Radio Variability and Random Walk Noise Properties of Four Blazars
Jong-Ho Park,Sascha Trippe
Physics , 2014, DOI: 10.1088/0004-637X/785/1/76
Abstract: We present the results of a time series analysis of the long-term radio lightcurves of four blazars: 3C 279, 3C 345, 3C 446, and BL Lacertae. We exploit the data base of the University of Michigan Radio Astronomy Observatory (UMRAO) monitoring program which provides densely sampled lightcurves spanning 32 years in time in three frequency bands located at 4.8, 8, and 14.5 GHz. Our sources show mostly flat or inverted (spectral indices -0.5 < alpha < 0) spectra, in agreement with optically thick emission. All lightcurves show strong variability on all time scales. Analyzing the time lags between the lightcurves from different frequency bands, we find that we can distinguish high-peaking flares and low-peaking flares in accord with the classification of Valtaoja et al. (1992). The periodograms (temporal power spectra) of the observed lightcurves are consistent with random-walk powerlaw noise without any indication of (quasi-)periodic variability. The fact that all four sources studied are in agreement with being random-walk noise emitters at radio wavelengths suggests that such behavior is a general property of blazars.
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