• Title/Summary/Keyword: X-events

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Laboratory Astrophysics using Intense X-ray from Free Electron Lasers

  • Chung, Moses
    • The Bulletin of The Korean Astronomical Society
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    • v.42 no.2
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    • pp.65.4-65.4
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    • 2017
  • The laboratory astrophysics is a new emerging field of basic sciences, and has tremendous discovery potentials. The laboratory astrophysics investigates the basic physical phenomena in the astrophysical objects in controlled and reproducible manners, which has become possible only recently due to the newly-established intense photon and ion beam facilities worldwide. In this presentation, we will introduce several promising ideas for laboratory astrophysics programs that might be readily incorporated in the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL). For example, precise spectroscopic measurements using Electron Beam Ion Trap (EBIT) and intense X-ray photons from the PAL-XFEL can be performed to explore the fundamental processes in high energy X-ray phenomena in the visible universe. Besides, in many violent astrophysical events, the energy density of matter becomes so high that the traditional plasma physics description becomes inapplicable. Generation of such high-energy density states can be also be achieved by using the intense photon beams available from the PAL-XFEL.

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THE OPTIMAL BIVARIATE BONFERRONI-TYPE LOWER BOUNDS

  • Lee, Min-Young
    • Communications of the Korean Mathematical Society
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    • v.14 no.4
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    • pp.789-795
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    • 1999
  • Let $A_1$,A$_2$…, A\ulcorner and B$_1$,B$_2$…, B\ulcorner be two sequences of events on the same probability space. Let X= X\ulcorner(A) and Y-Y\ulcorner)(B), repectively, by the number of those A\ulcorner and B\ulcorner which oc-cur. We establish bivariate lower bounds on the distribution P(X$\geq$1, Y, $\geq$1)and P(X$\geq$i , $Y\geq$j)by linear combinations of the bino-mial moments S\ulcorner, \ulcorner, 1$\leq$i$\leq$j

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Analysis of Suspended Solid Generation with Rainfall-Runoff Events in a Small Forest Watershed (산림 소유역에서 강우-유출에 따른 부유토사 발생 특성 분석)

  • Kim, Jae-Hoon;Choi, Hyung-Tae;Lim, Hong-Geun
    • Journal of Environmental Science International
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    • v.24 no.12
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    • pp.1617-1627
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    • 2015
  • This study was carried out to investigate the characteristics of suspended solid concentration in small forest watershed, Hwacheon, Gangwondo. For five rainfall events from July 2013 to August 2013, rainfall, discharge, and suspended solid load has been measured. The results showed that the fist flush effect was observed for suspended solid in each rainfall event, sediment rating curve was obtained with $y=30.029x^{1.573}$ at rising limb and $y=12.902x^{1.8827}$ at falling limb, and EMC (event mean concentration) of suspended solid was calculated to 9.4 mg/L. EMC was compared to the values from the watershed that has various land use types and EMC from forest watershed was much lower that from the crop, paddy or low covered forest watershed.

The Relationships among Experiences of Traumatic Events, Post-traumatic Stress and the Needs for Health Promotion Programs of 119 Paramedics (119구급대원의 외상사건 경험, 외상후 스트레스와 건강증진 프로그램 요구도와의 관계)

  • Kang, Mi Suk;Kim, Young Im;Geun, Hyo Geun
    • Research in Community and Public Health Nursing
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    • v.28 no.4
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    • pp.524-536
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    • 2017
  • Purpose: This study aims to examine the relationships among experiences of traumatic events, post-traumatic stress (PTS), and the needs for health promotion programs of 119 paramedics. Methods: Experiences of traumatic events, PTS, and needs for health promotion programs were measured using a structured questionnaire. The subjects were 193 paramedics in Jeju Island. Data were analyzed using descriptive statistics, t-test and $x^2$ test. Results: The most experienced event out of the 16 different traumatic events was 'retrieve a suicide's body.' A high-risk classification of PTS was observed in 36.2% of the subjects. The rates of experiences were higher than those of the actual needs for all 26 health promotion programs. The programs reported as highly needed by respondents were stress management (75.5%) followed by exercise (74.6%) and PTS management (72.5%). Subjects with longer career periods, a fire sergeant, perceived obesity, numerous experiences of traumatic events, and in the PTS risk group had a higher need for a stress management program. Conclusion: These findings indicate that a significant number of 119 paramedics experienced PTS. They also show that onsite strategic management is strongly required. In addition, implementation of health promotion programs based on the needs of 119 paramedics is highly needed.

EphrinB1 interacts with the transcriptional co-repressor Groucho/xTLE4

  • Kamata, Teddy;Bong, Yong-Sik;Mood, Kathleen;Park, Mae-Ja;Nishanian, Tagvor G.;Lee, Hyun-Shik
    • BMB Reports
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    • v.44 no.3
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    • pp.199-204
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    • 2011
  • Ephrin signaling is involved in various morphogenetic events, such as axon guidance, hindbrain segmentation, and angiogenesis. We conducted a yeast two-hybrid screen using the intracellular domain (ICD) of EphrinB1 to gain biochemical insight into the function of the EphrinB1 ICD. We identified the transcriptional co-repressor xTLE1/Groucho as an EphrinB1 interacting protein. Whole-mount in situ hybridization of Xenopus embryos confirmed the co-localization of EphrinB1 and a Xenopus counterpart to TLE1, xTLE4, during various stages of development. The EphrinB1/xTLE4 interaction was confirmed by co-immunoprecipitation experiments. Further characterization of the interaction revealed that the carboxy-terminal PDZ binding motif of EphrinB1 and the SP domain of xTLE4 are required for binding. Additionally, phosphorylation of EphrinB1 by a constitutively activated fibroblast growth factor receptor resulted in loss of the interaction, suggesting that the interaction is modulated by tyrosine phosphorylation of the EphrinB1 ICD.

Gait-Event Detection for FES Locomotion (FES 보행을 위한 보행 이벤트 검출)

  • Heo Ji-Un;Kim Chul-Seung;Eom Gwang-Moon
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.3 s.168
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    • pp.170-178
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    • 2005
  • The purpose of this study is to develop a gait-event detection system, which is necessary for the cycle-to-cycle FES control of locomotion. Proposed gait event detection system consists of a signal measurement part and gait event detection part. The signal measurement was composed of the sensors and the LabVIEW program for the data acquisition and synchronization of the sensor signals. We also used a video camera and a motion capture system to get the reference gait events. Machine learning technique with ANN (artificial neural network) was adopted for automatic detection of gait events. 2 cycles of reference gait events were used as the teacher signals for ANN training and the remnants ($2\sim5$ cycles) were used fur the evaluation of the performance in gait-event detection. 14 combinations of sensor signals were used in the training and evaluation of ANN to examine the relationship between the number of sensors and the gait-event detection performance. The best combinations with minimum errors of event-detection time were 1) goniometer, foot-switch and 2) goniometer, foot-switch, accelerometer x(anterior-posterior) component. It is expected that the result of this study will be useful in the design of cycle-to-cycle FES controller.

Magnetic and kinematic characteristics of very fast CMEs

  • Jang, Soojeong;Moon, Yong-Jae;Lim, Daye;Lee, Jae-Ok;Lee, Harim;Park, Eunsu
    • The Bulletin of The Korean Astronomical Society
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    • v.43 no.1
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    • pp.54.2-54.2
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    • 2018
  • It is important to understand very fast CMEs which are the main cause of geomagnetic storms and solar particle events (SPEs). During this solar cycle 24, there are 10 very fast CMEs whose speeds are over 2000 km/s. Among these, there were only two fronside events (2012 January 23 and 2012 March 7) and they are associated with two major flares (M8.7 and X5.4) and the most strong SPEs (6310 pfu and 6530 pfu). They have a similar characteristics: there were successive CMEs within 2 hours in the same active region. We analyze their magnetic properties using SDO HMI magnetograms and kinematic ones from STEREO EUVI/COR1/COR2 observations. We can measure their speeds and initial accelerations without projection effects because their source locations are almost the limb. Additionally, we are investigating magnetic and kinematic characteristics of 8 backside events using AI-generated magnetograms constructed by deep learning methods.

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Ground Reaction Force and Foot Pressure Analysis During Golf Iron Swing by Gender (골프 아이언 스윙 시 성별에 따른 지면반력 및 족저압력 분석)

  • Park, Jae-Young
    • Korean Journal of Applied Biomechanics
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    • v.20 no.2
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    • pp.167-174
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    • 2010
  • This study aims to quantitatively compare and analyze kinetic variables in the motion of male and female professional golfers to suggest basic scientific materials for golf iron swing. Five male and five female professional golfers participated in this experiment. Ground reaction force and foot pressure were measured during performing 10 swings for each participants using an iron club. The result of the ground reaction force indicates that the force occurs at the left foot toward right(-) direction in the mid-downswing(E3) and impact(E4) events in X-axis, while it occurs at the right foot toward anterior(-) direction in Y-axis for both male and female, showing a big difference between them. Also, in Z-axis, large force occurs at the left foot in most events. The analyzed result on foot pressure indicates that men have the highest pressure and area at the left foot, and women have the highest ones at the right foot in the mid-downswing(E3) and impact(E4) events in the max foot pressure, ground contact area and average pressure. It is considered that there is difference of central movement methods between men and women. Thus, different education and training on golf swing should be necessary by gender due to their different patterns of golf iron swing.

MERGERS, COSMIC RAYS, AND NONTHERMAL PROCESSES IN CLUSTERS OF GALAXIES

  • SARAZIN CRAIG L.
    • Journal of The Korean Astronomical Society
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    • v.37 no.5
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    • pp.433-438
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    • 2004
  • Clusters of galaxies generally form by the gravitational merger of smaller clusters and groups. Major cluster mergers are the most energetic events in the Universe since the Big Bang. The basic properties of cluster mergers and their effects are discussed. Mergers drive shocks into the intracluster gas, and these shocks heat the intracluster gas. As a result of the impulsive heating and compression associated with mergers, there is a large transient increase in the X-ray luminosities and temperatures of merging clusters. These merger boost can affect X-ray surveys of clusters and their cosmological interpretation. Similar boosts occur in the strong lensing cross-sections and Sunyaev-Zeldovich effect in merging clusters. Merger shock and turbulence associated with mergers should also (re)accelerate nonthermal relativistic particles. As a result of particle acceleration in shocks and turbulent acceleration following mergers, clusters of galaxies should contain very large populations of relativistic electrons and ions. Observations and models for the radio, extreme ultraviolet, hard X-ray, and gamma-ray emission from nonthermal particles accelerated in these shocks will also be described. Gamma-ray observations with GLAST seem particularly promising.