• Geophysics and Geophysical Exploration
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• v.6 no.2
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• pp.87-94
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• 2003

ULF geomagnetic field anomalies related to earthquakes have been reported and a mechnism that magnetic field variations could be generated by the induced telluric current due to the high frequency fluctuation of conductivity in a fault Bone have been proposed. In this study, we calculated electromagnetic anomalies using a simple fault model and investigated the possibility of significant perturbation. Since low frequency electromagnetic fields are modulated by the high frequency oscillation of conductivity and the modulated fields are concentrated in a narrow ULF band, the electromagnetic fields in ULF band could be perturbed significantly. The amplitude of electromagnetic field anomaly depends on various factors: the geometry and conductivity of fault zone, the magnitude and frequency of conductivity fluctuation, the resistivity structure of crust or mantle, the frequency bandwidth of observational data and so on. Therefore, it is strongly required to reveal the deep resistivity structure of crust a.: well ah the structure of fault zone and to ,select the optimal observation frequency band for the observation of electromagnetic activities related with earthquakes.

• Korean Journal of Optics and Photonics
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• v.28 no.6
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• pp.327-333
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• 2017

The purpose of this research was to analyze characteristics of verbal interactions of each homogeneous group in the learning of the 6th grade's 'Use of Lenses' Unit. For this research, six learning sessions were conducted in one 6th grade class composed of a high-academic-achievement group, an intermediate-academic-achievement group, and a low-academic-achievement group. All lessons were recorded, to analyze the verbal interactions of each group, and the transcribed data were analyzed using the verbal-interaction analytic framework. Results included: In the upper group, although opinions were presented more frequently, there were many negative verbal interactions in completing the tasks. The middle group was observed more specifically to accept peer opinions critically in their observational activities. The middle group's members were more active in presenting their opinions than listening to others' opinions. The lower group had difficulties in drawing conclusions because of a lack of ability to persuade peers or to respect the opinions of peers, even though the frequency of verbal interactions was higher than in other groups. Therefore, a homogeneous group structure is good for a simple activity involving a simple inquiry or an exchange of opinions, while a heterogeneous group structure is more effective in activities focused on understanding scientific concepts and knowledge.

• Journal of Hospice and Palliative Care
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• v.19 no.3
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• pp.233-239
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• 2016

Purpose: Little is known regarding the factors associated with the willingness of family caregivers of terminal cancer patients to participate in a bereaved survey. This study aimed to ascertain the pre-loss factors that predict actual participation in a bereaved survey. Methods: We conducted a prospective observational study using data from two multi-center surveys at the end-of-life and after loss. In order to identify the pre-loss factors associated with participating in the bereaved survey, we used a step-wise multivariate logistic regression analysis. Results: Among 185 bereaved individuals, 30 responded to the survey (response rate: 16.2%). There were differences between the participation group and the non-participation group regarding religion, economic status, and perceived quality of care as assessed by the Quality Care Questionnaire-End of Life. A final multivariate model revealed that bereaved individuals who professed a religion (adjusted odds ratio [aOR]=5.01; P=0.008), had a high income (aOR=4.86, P=0.003), and satisfied with the care for familial relationship (aOR=4.49, P=0.003) were more likely to engage in the bereaved survey. Conclusion: Our finding suggests that improving the quality of end-of-life care may promote actual participation in a bereaved survey through easing post-loss distress. More attention should also be paid to those bereaved individuals who are hesitant to participate in a bereaved survey.

• Pediatric Infection and Vaccine
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• v.26 no.3
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• pp.140-147
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• 2019

Purpose: Staphylococcus aureus is a major cause of skin and soft tissue infections (SSTIs). This study aimed to determine the temporal trends in antibiotic susceptibility of S. aureus in SSTI patients aged <19 years. Methods: This retrospective observational study was conducted in pediatric patients with SSTI caused by community-associated S. aureus. Microbiologic and demographic data were collected, and the trends of antibiotic susceptibility results were evaluated. Results: From January 2010 to December 2018, a total of 807 S. aureus isolates were included. An overall increase in susceptibility of isolates to oxacillin was noted (P<0.001), with 75.0% of isolates being oxacillin-susceptible in 2018. S. aureus remained highly susceptible to trimethoprim/sulfamethoxazole and tetracycline, with 97.6% and 95.2% isolate susceptibility in 2018, respectively. Isolates from younger children aged 1 to 5 years had a significantly lower rate of susceptibility to oxacillin than older children aged 6 to 18 years (53.4% vs. 75.0%, P<0.001). Conclusions: The proportion of methicillin-resistant S. aureus isolates appears to decrease in pediatric patients with community-associated SSTI caused by S. aureus. Clinicians should be aware of regional susceptibility patterns when choosing empirical regimens.

• Journal of The Korean Astronomical Society
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• v.37 no.1
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• pp.41-53
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• 2004

It has been a big mystery what drives filament eruptions and flares. We have studied in detail an X1.8 flare and its associated filament eruption that occurred in NOAA Active Region 9236 on November 24,2000. For this work we have analyzed high temporal (about 1 minute) and spatial (about 1 arcsec) resolution images taken by Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory, Hoc centerline and blue wing ($-0.6{\AA}$) images from Big Bear Solar Observatory, and 1600 ${\AA}$ UV images by the Transition Region and Corona Explorer (TRACE). We have found that there were several transient brightenings seen in H$\alpha$ and, more noticeably in TRACE 1600 ${\AA}$ images around the preflare phase. A closer look at the UV brightenings in 1600 ${\AA}$ images reveals that they took place near one end of the erupting filament, and are a kind of jets supplying mass into the transient loops seen in 1600 ${\AA}$. These brightenings were also associated with canceling magnetic features (CMFs) as seen in the MDI magnetograms. The flux variations of these CMFs suggest that the flux cancellation may have been driven by the emergence of the new flux. For this event, we have estimated the ejection speeds of the filament ranging from 10 to 160 km $s^{-1}$ for the first twenty minutes. It is noted that the initiation of the filament eruption (as defined by the rise speed less than 20 km $s^{-1}$) coincided with the preflare activity characterized by UV brightenings and CMFs. The speed of the associated LASCO CME can be well extrapolated from the observed filament speed and its direction is consistent with those of the disturbed UV loops associated with the preflare activity. Supposing the H$\alpha$/UV transient brightenings and the canceling magnetic features are due to magnetic reconnect ion in the low atmosphere, our results may be strong observational evidence supporting that the initiation of the filament eruption and the preflare phase of the associated flare may be physically related to low-atmosphere magnetic reconnection.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.82-82
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• 2010

We measure the topology of the galaxy distribution using the Seventh Data Release of the Sloan Digital Sky Survey (SDSS DR7), examining the dependence of galaxy clustering topology on galaxy properties. The observational results are used to test galaxy formation models. A volume-limited sample defined by Mr<-20.19 enables us to measure the genus curve with amplitude of G=378 at 6h-1Mpc smoothing scale, with 4.8% uncertainty including all systematics and cosmic variance. The clustering topology over the smoothing length interval from 6 to 10h-1Mpc reveals a mild scale-dependence for the shift and void abundance (A_V) parameters of the genus curve. We find strong bias in the topology of galaxy clustering with respect to the predicted topology of the matter distribution, which is also scale-dependent. The luminosity dependence of galaxy clustering topology discovered by Park et al. (2005) is confirmed: the distribution of relatively brighter galaxies shows a greater prevalence of isolated clusters and more percolated voids. We find that galaxy clustering topology depends also on morphology and color. Even though early (late)-type galaxies show topology similar to that of red (blue) galaxies, the morphology dependence of topology is not identical to the color dependence. In particular, the void abundance parameter A_V depends on morphology more strongly than on color. We test five galaxy assignment schemes applied to cosmological N-body simulations to generate mock galaxies: the Halo-Galaxy one-to-one Correspondence (HGC) model, the Halo Occupation Distribution (HOD) model, and three implementations of Semi-Analytic Models (SAMs). None of the models reproduces all aspects of the observed clustering topology; the deviations vary from one model to another but include statistically significant discrepancies in the abundance of isolated voids or isolated clusters and the amplitude and overall shift of the genus curve. SAM predictions of the topology color-dependence are usually correct in sign but incorrect in magnitude.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.40.1-40.1
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• 2017

The NISS (Near-infrared Imaging Spectrometer for Star formation history) is the near-infrared spectro-photometric instrument optimized to the Next Generation of small satellite series (NEXTSat). To achieve the major scientific objectives for the study of the cosmic star formation in local and distant universe, the spectro-photometric survey covering more than 100 square degree will be performed. The main observational targets will be nearby galaxies, galaxy clusters, star-forming regions and low background regions. The off-axis optics was developed to cover a wide field of view ($2deg.{\times}2deg.$) as well as the wide wavelength range from 0.95 to $2.5{\mu}m$, which were revised based upon the recent test and evaluation of the NISS instrument. The mechanical structure were tested under the launching condition as well as the space environment. The signal processing from infrared sensor and the communication with the satellite were evaluated after the integration into the satellite. The flight model of the NSS was assembled and integrated into the satellite. To verify operations of the satellite in space, the space environment tests such as the vibration, shock and thermal-vacuum test were performed. The accurate calibration data were obtained in our test facilities. Here, we report the test results of the flight model of the NISS.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.41.1-41.1
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• 2018

We introduce a current status and future plans of Korea Microlensing Telescope Network (KMTNet) microlensing experiments, which include an observational strategy, pipeline, event-finder, and collaborations with Spitzer. The KMTNet experiments were initiated in 2015. From 2016, KMTNet observes 27 fields including 6 main fields and 21 subfields. In 2017, we have finished the DIA photometry for all 2016 and 2017 data. Thus, it is possible to do a real-time DIA photometry from 2018. The DIA photometric data is used for finding events from the KMTNet event-finder. The KMTNet event-finder has been improved relative to the previous version, which already found 857 events in 4 main fields of 2015. We have applied the improved version to all 2016 data. As a result, we find that 2597 events are found, and out of them, 265 are found in KMTNet-K2C9 overlapping fields. For increasing the detection efficiency of event-finder, we are working on filtering false events out by machine-learning method. In 2018, we plan to measure event detection efficiency of KMTNet by injecting fake events into the pipeline near the image level. Thanks to high-cadence observations, KMTNet found fruitful interesting events including exoplanets and brown dwarfs, which were not found by other groups. Masses of such exoplanets and brown dwarfs are measured from collaborations with Spitzer and other groups. Especially, KMTNet has been closely cooperating with Spitzer from 2015. Thus, KMTNet observes Spitzer fields. As a result, we could measure the microlens parallaxes for many events. Also, the automated KMTNet PySIS pipeline was developed before the 2017 Spitzer season and it played a very important role in selecting the Spitzer target. For the 2018 Spitzer season, we will improve the PySIS pipeline to obtain better photometric results.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.64.1-64.1
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• 2018

SNe light curves have been used to understand the expansion history of the universe, and a lot of efforts have gone into understanding the overall shape of the radioactively powered light curve. However, we still have little direct observational evidence for the theorized SN progenitor systems. Recent studies suggest that the light curve of a supernova shortly after its explosion (< 1 day) contains valuable information about its progenitor system and can be used to set a limit on the progenitor size, R*. In order to catch the early light curve of SNe explosion and understand SNe progenitors, we are performing a ~8hr interval monitoring survey of nearby galaxies (d < 50 Mpc) with 1-m class telescopes around the world. Through this survey, we expect to catch the very early precursor emission as faint as R=21 mag (~0.1 Rsun for the progenitor). In this poster, we outline this project, and present a few scientific highlights, such as the early light curve of SN 2015F in NGC 2442.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.7 no.2
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• pp.208-221
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• 2000

The objective of this research was to compare the flushing effects using 1:1,000 diluted heparin or 0.9% normal saline in relation to needle gauge and frequency of IV medications. The comparative categories were clotting, duration of patency, and incidence of phlebitis. The design of research was a Nonequivalent Control group, Post test, Nonsynchrorized Design. The independent variable was 0.9% normal saline flushing the IV locks and the dependent variables were clotting, duration of patency, and incidence of phlebitis. Subjects were medical-surgical inpatients over 15 years old and with peripherally placed IVs who were hospitalized in a university medical center. Exclusion criteria included foreigners and those who were rejected for this research. The final sample for data analysis included 295 IV sites in 194 patients; 154 were in the saline group and 141 were in the heparin group. Subjects were assigned to have IV locks is flushed with 0.9% normal saline in the experimental group and to have IV lock flushed with 1:1,000 diluted heparin(100 units) in the control group. In order to increase reliability, the nurses who were assigned to the units involved in the study received an explanation on the standard method for locking an IV, recording method for observational data and criteria for the detection of phlebitis. Data were collected for a period of 2 weeks, from March 16, 2000 to March 29, 2000. Total duration of IV was defined the time of IV insertion to the time of discontinuation. Phlebitis was defined as the presence of the following : pain, swelling. erythema at the insertion site. Chi-square was used to determine the association between the degree of clotting, duration of patency, and incidence of phlebitis for the diluted heparin or the normal saline and needle gauge and frequency of IV medications. The results are summarized as follows : (a) There was difference in the degree of clotting between two groups($X^2=5.882$, p=.015). (b) There was no difference in the degree of duration of patency between two groups($X^2=2.439$, p=.295). (c) There was no difference in the incidence of phlebitis between two groups($X^2=0.190$, p=.663). (d) There was difference in the degree of clotting($X^2=6.209$, p=.013) and in the degree of duration of patency($X^2=6.978$, p=.031) according the needle guage between the two groups. (e) There was difference in the incidence of phlebitis($X^2=5.008$, p=.025) according to the frequencies of IV injection between two groups.