• Clinical and Experimental Pediatrics
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• v.62 no.5
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• pp.187-192
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• 2019

Purpose: The importance of the neurodevelopmental outcomes of very-low-birth-weight (VLBW) infants has been emphasized as their mortality rate has markedly improved. This study aimed to assess the validity of the Korean Developmental Screening Test (K-DST), a developmental screening tool approved by the Korean Society of Pediatrics, for the timely diagnosis of neurodevelopmental delay in VLBW infants. Methods: Subjects included VLBW infants enrolled in the Korean Neonatal Network database between January 2012 and December 2014. The collected data were analyzed for sensitivity, specificity, positive predictive value, and negative predictive value (NPV) in the K-DST compared to those in the Bayley Scales of Infant Development-II for VLBW infants. Results: A total of 173 patients were enrolled. Their mean gestational age and mean birth weight were $27.5{\pm}2.8weeks$ and $980.5{\pm}272.1g$, respectively. The frequency of failed psychomotor developmental index (PDI) <85 was similar to that in at least one domain of K-DST <1 standard deviation. Failure in more than one K-DST domain compared with a mental developmental index (MDI) <85 showed a sensitivity and NPV of 73.2% and 75.0%, respectively. Failure in more than one K-DST domain compared with PDI <85 showed a sensitivity and NPV of 60.3% and 71.6%, respectively. Each K-DST domain had a stronger correlation with predicting a failing MDI <85 than a failing PDI <85 (P<0.05). Conclusion: K-DST could be a useful screening tool for predicting mental developmental delay in VLBW infants and referring them for neurodevelopmental assessments.

• Journal of Astronomy and Space Sciences
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• v.30 no.1
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• pp.43-48
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• 2013

The geomagnetic activity shows the semiannual variation stronger in vernal and autumnal equinoxes than in summer and winter solstices. The semiannual variation has been explained by three main hypotheses such as Axial hypothesis, Equinoctial hypothesis, and Russell-McPherron Effect. Many studies using the various geomagnetic indices have done to support three main hypotheses. In recent, Oh & Yi (2011) examined the solar magnetic polarity dependency of the geomagnetic storm occurrence defined by Dst index. They reported that there is no dependency of the semiannual variation on the sign of the solar polar fields. This study examines the solar magnetic polarity dependency of quiet time geomagnetic activity. Using Dxt index (Karinen & Mursula 2005) and Dcx index (Mursula & Karinen 2005) which are recently suggested, in addition to Dst index, we analyze the data of three-year at each solar minimum for eight solar cycles since 1932. As a result, the geomagnetic activity is stronger in the period that the solar magnetic polarity is anti-parallel with the Earth's magnetic polarity. There exists the difference between vernal and autumnal equinoxes regarding the solar magnetic polarity dependency. However, the difference is not statistically significant. Thus, we conclude that there is no solar magnetic polarity dependency of the semiannual variation for quiet time geomagnetic activity.

• Journal of Astronomy and Space Sciences
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• v.20 no.2
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• pp.109-122
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• 2003

To examine the causal relationship between geomagnetic storm and substorm, we investigate the correlation between dispersionless particle injection rate of proton flux observed from geosynchronous satellites, which is known to be a typical indicator of the substorm expansion activity, and Dst index during magnetic storms. We utilize geomagnetic storms occurred during the period of 1996 ~ 2000 and categorize them into three classes in terms of the minimum value of the Dst index ($Dst_{min}$); intense ($-200nT{$\leq$}Dst_{min}{$\leq$}-100nT$), moderate($-100nT{\leq}Dst_{min}{\leq}-50nT$), and small ($-50nT{\leq}Dst_{min}{\leq}-30nT$) -30nT)storms. We use the proton flux of the energy range from 50 keV to 670 keV, the major constituents of the ring current particles, observed from the LANL geosynchronous satellites located within the local time sector from 18:00 MLT to 04:00 MLT. We also examine the flux ratio ($f_{max}/f_{ave}$) to estimate particle energy injection rate into the inner magnetosphere, with $f_{ave}$ and $f_{max}$ being the flux levels during quiet and onset levels, respectively. The total energy injection rate into the inner magnetosphere can not be estimated from particle measurements by one or two satellites. However, the total energy injection rate should be at least proportional to the flux ratio and the injection frequency. Thus we propose a quantity, “total energy injection parameter (TEIP)”, defined by the product of the flux ratio and the injection frequency as an indicator of the injected energy into the inner magnetosphere. To investigate the phase dependence of the substorm contribution to the development of magnetic storm, we examine the correlations during the two intervals, main and recovery phase of storm separately. Several interesting tendencies are noted particularly during the main phase of storm. First, the average particle injection frequency tends to increase with the storm size with the correlation coefficient being 0.83. Second, the flux ratio ($f_{max}/f_{ave}$) tends to be higher during large storms. The correlation coefficient between $Dst_{min}$ and the flux ratio is generally high, for example, 0.74 for the 75~113 keV energy channel. Third, it is also worth mentioning that there is a high correlation between the TEIP and $Dst_{min}$ with the highest coefficient (0.80) being recorded for the energy channel of 75~113 keV, the typical particle energies of the ring current belt. Fourth, the particle injection during the recovery phase tends to make the storms longer. It is particularly the case for intense storms. These characteristics observed during the main phase of the magnetic storm indicate that substorm expansion activity is closely associated with the development of mangetic storm.

• Journal of Astronomy and Space Sciences
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• v.28 no.2
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• pp.123-132
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• 2011

It is generally believed that the occurrence of a magnetic storm depends upon the solar wind conditions, particularly the southward interplanetary magnetic field (IMF) component. To understand the relationship between solar wind parameters and magnetic storms, variations in magnetic field polarity and solar wind parameters during magnetic storms are examined. A total of 156 storms during the period of 1997~2003 are used. According to the interplanetary driver, magnetic storms are divided into three types, which are coronal mass ejection (CME)-driven storms, co-rotating interaction region (CIR)-driven storms, and complicated type storms. Complicated types were not included in this study. For this purpose, the manner in which the direction change of IMF $B_y$ and $B_z$ components (in geocentric solar magnetospheric coordinate system coordinate) during the main phase is related with the development of the storm is examined. The time-integrated solar wind parameters are compared with the time-integrated disturbance storm time (Dst) index during the main phase of each magnetic storm. The time lag with the storm size is also investigated. Some results are worth noting: CME-driven storms, under steady conditions of $B_z$ < 0, represent more than half of the storms in number. That is, it is found that the average number of storms for negative sign of IMF $B_z$ (T1~T4) is high, at 56.4%, 53.0%, and 63.7% in each storm category, respectively. However, for the CIR-driven storms, the percentage of moderate storms is only 29.2%, while the number of intense storms is more than half (60.0%) under the $B_z$ < 0 condition. It is found that the correlation is highest between the time-integrated IMF $B_z$ and the time-integrated Dst index for the CME-driven storms. On the other hand, for the CIR-driven storms, a high correlation is found, with the correlation coefficient being 0.93, between time-integrated Dst index and time-integrated solar wind speed, while a low correlation, 0.51, is found between timeintegrated $B_z$ and time-integrated Dst index. The relationship between storm size and time lag in terms of hours from $B_z$ minimum to Dst minimum values is investigated. For the CME-driven storms, time lag of 26% of moderate storms is one hour, whereas time lag of 33% of moderate storms is two hours for the CIR-driven storms. The average values of solar wind parameters for the CME and CIR-driven storms are also examined. The average values of ${\mid}Dst_{min}{\mid}$ and ${\mid}B_{zmin}{\mid}$ for the CME-driven storms are higher than those of CIR-driven storms, while the average value of temperature is lower.

• Bulletin of the Korean Space Science Society
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• 2003.05b
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• pp.55-55
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• 2003

• The Bulletin of The Korean Astronomical Society
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• v.26 no.1
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• pp.42-42
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• 2001

• Korean Journal of Exercise Nutrition
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• v.13 no.1
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• pp.9-14
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• 2009

The effects of a hypocaloric diet with or without strength training on body fat distribution and serum lipid concentrations in obese elderly women were investigated. Twenty-six healthy women (age 66±4.6 yr; body mass index 32.3±2.9 kg/m²) were randomly assigned to 3 groups: control (C; n=8), hypocaloric diet (DO; n=9) or hypocaloric diet with strength training (DST; n=9). Subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and inter and intra muscular adipose tissue (IMAT) were measured using magnetic resonance imaging. Serum lipid concentrations including total cholesterol (TC), high density lipoprotein cholesterol (HDLC), low density lipoprotein cholesterol (LDLC), and triglycerides (TG) were measured. No significant changes occurred in body weight and percent body fat in the C group over the 16-week period. The DO and DST groups lost similar amounts of weight and fat after 16 weeks. SAT and VAT decreased after weight loss in the DO and DST groups but not in the C group. IMAT was significantly reduced in the DO and DST groups, whereas in the C group IMAT increased. The loss in IMAT mass was similar in the DO and DST groups. TC and LDLC decreased in the DO and DST groups but not in the C group. There were no differences between the DO and DST groups in decrease in TC and LDLC. HDLC decreased in the DO group but not in the C and DST groups. TG tended to decrease in the DST group. In conclusion, body fat distribution including SAT, VAT, and IMAT and serum lipid concentratons were modulated by weight loss resulting from the hypocaloric diet with or without strength training in obese elderly women. Strength training did not enhance the improvement in body fat distribution and serum TC and LDLC concentrations by the hypocaloric diet.

• The Bulletin of The Korean Astronomical Society
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• v.24 no.2
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• pp.69-69
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• 1999

• Bulletin of the Korean Space Science Society
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• 1999.09a
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• pp.61-61
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• 1999

• The Bulletin of The Korean Astronomical Society
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• v.25 no.1
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• pp.19-19
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• 2000