• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.68.2-68.2
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• 2014

High Frequency Peakers (HFPs) are radio-loud Active Galactic Nuclei (AGN), which are regarded as being in the earliest evolutionary phase (102-103 years) of radio galaxies. They are expected to be small in size (< ~1 kpc) compared to their host galaxies (~a few 10s kpc), and have convex spectra, which are peaking at high radio frequency (> 5 GHz). Their size and spectral shape are the most obvious supporting evidence of extremely young ages. HFPs are therefore ideal targets to probe the earliest stage of radio sources. To date however, the young radio source classification has been relying mainly on the spectral shape which usually does not cover high enough frequencies where the true peak flux is located. Hence HFPs are often confused with blazars which may show a similar spectral shape and apparent compactness but are a somewhat evolved form of AGNs. Therefore, we have been challenging to identify HFPs among the sample of 19 candidates using the Korean VLBI Network (KVN) which enables us to extend the radio spectrum baseline up to 22 and 43 GHz. These are higher than the frequencies used in most previous studies of HFPs, allowing us to select genuine HFPs. By long-term monitoring of 18 epochs, we have also inspected the variability of the sample to select out blazars which are highly variable yet with a similar radio spectrum. In this work, we present the light curves and spectral properties of the HFP candidates. We discuss the results of our re-identification of HFPs.

• Journal of Biosystems Engineering
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• v.28 no.3
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• pp.245-252
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• 2003

This study was investigated the possibility of measuring chlorophyll in paddy crops using two kinds of chlorophyll meters(SPAD-502, Field Scout). The results of correlation analysis showed the 0.7758(r$^2$) relationship between the chlorophyll contents of paddy leaves measured by SPAD and spectrophotometer. It indicates that chlorophyll content in paddy crops could be measured using the SPAD. Considering the data of the SPAD and Field Scout there was significant difference between their chlorophyll contents measured by the SPAD and Field Scout. Likewise, such results were consistent with the corrected data using light intensity. According to the results, it can be concluded that it is difficult to describe the rice chlorophyll measured by the Field Scout more accurately than the SPAD when using one standard spectrum and another spectrum for reflectance measuring. The chlorophyll variance measured at a research institute and a farmer's field revealed that the output of SPAD was more reliable than that of the Field Scout.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.399-403
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• 1998

Absorption coefficient per mass unit of particles, specific absorption coefficient, is one of main parameters in developing algorithms for ocean color remote sensing. Specific absorption coefficient of chlorophyll (a$^*_{ph}$) and suspended sediment (SS) were analyzed by "wet filter technique" and "Kishino method" for data sets observed in the Yellow and Mediterranean Seas. A new data-recovering method for the filter technique was also developed using spectrum slopes. This method recovered the baseline of spectrum that was often missed in the Kishino method. High a$^*_{ph}$($\lambda$) values in the oligotrophic Mediterranean Sea and low values in the Yellow Sea were observed, spanning over the range of 0.02 to 0.12 $m^2$/mg, at the chlorophyll maximum absorption wavelength 440nm. The empirical relationship between a$^*_{ph}$ and chlorophyll concentration was found to fit a power function, which was slightly different from that proposed by Bricaud et ai. (1995). Absorption specific coefficients for suspended sediment (a$^*_{SS}$) didn't show any relationship with concentrations of suspended sediment. However, the average value of a$^*_{SS}$ at 440nm was close to the specific absorption coefficient of soil (loess) measured by Ahn (1990). The more-pronounced variability of a$^*_{SS}$ than a$^*_{ph}$ perhaps can explain more wide range of size-distribution for SS, which were determined by their specific gravity and agitation of water mass in the sea surface.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.125-128
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• 2005

In this paper, we argue that the gigahertz peaked spectrum (GPS) quasars are special blazars, blazars in dense and dusty gas enviornment. The ROSAT detection rate of GPS quasars is similar to that of flat spectrum radio quasars (FSRQs), suggesting that the relativistic jets in GPS quasars are oriented at small angle to the line of sight. Due to strong inverse Compton scattering off infrared photons from dense and dusty nuclear interstellar media in GPS quasars, most of them may have significant soft gamma-ray and X-ray emission, which is consistent with ASCA X-ray observations. Because Compton cooling in GPS quasars is stronger than that in FSRQs, synchrotron emission in GPS quasars may less dominate over thermal emission of the accretion disk and hot dust, hence most GPS quasars show low optical polarization and small variability, consistent with observations. We suggest that it is the significant radio emission of electron/positron pairs produced by the interaction of gamma-rays with the dense gas and dust grains in GPS quasars that makes GPS quasars show steep radio spectra, low radio polarization, and relatively faint VLBI/VLBA cores. Whether GPS quasars are special blazars can be tested by gamma-ray observations with GLAST in the near future, with the detection rate of GPS quasars being similar to that of FSRQs.

• Journal of Genetic Medicine
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• v.17 no.2
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• pp.79-82
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• 2020

In epilepsy-aphasia spectrum (EAS) disorders, mutations in the glutamate receptor ionotropic N-methyl-D-aspartate type subunit 2A (GRIN2A) have become important for screening the disease. Research into the phenotypic variability of several types of neurologic impairment involving these mutations is in progress. However, the non-neurological problems related to these mutations are poorly understood. EAS disorders usually have epileptic, cognitive, or behavioral manifestations. In this case report, we present a female patient with epilepsy, delay in expressive language and social development, and intellectual disability with low intelligence quotient and memory quotient, but normal motor development. Through genetic analysis, she was found to have a missense and a nonsense mutation in GRIN2A (c.1770A>C; p.Lys509Asn and c.3187G>T; p.Glu1063∗, respectively) and we consider the nonsense mutation as 'pathogenic variant'. She was also discovered to have congenital hypothyroidism, growth hormone deficiency and Rathke's cleft cyst in the brain, which were previously unknown features of GRIN2A mutation. Our findings should widen understanding of the spectrum of GRIN2A phenotypes, and emphasize the need for more research into the association between GRIN2A mutations and non-neurologic clinical presentations.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.2
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• pp.89-105
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• 2008

Sea level and atmospheric pressure data of 1999-2005 from four stations along the Korean east coast were analyzed to understand the sea level variability and its causal mechanism. The results of the wavelet and the auto-spectrum analyses indicate that the sea level fluctuations of 3-17 day period are statistically significant at the 95% confidence level, especially in spring to early summer. In this period, the coherency between the sea levels and the atmospheric pressures in a cross-spectrum is high, implying the importance of an inverted barometric effect in generation of the sea level fluctuations. To learn about the sea level variability, the cross-spectrum analyses were applied between the sea levels of the adjacent stations. The results show a case of southward phase propagations along the coast, as in 1999, 2003 and 2005, and an another case of no progressive phase lags between the stations, as in 2000-2002, and 2004. The phase speed in the former case is 12-15 m/s, which is a commonly observed phase speed of coastal Kelvin waves. Generation of such fluctuations seems to be related to low pressure cells developed in the Asian continent in spring and summer and moving eastward over the coastal region north of the stations. The latter case of no progressive phase lag, however, occurs when the low pressure cells developed in the continent move along the region south of the stations. In this case, the northeastward phase propagation with a speed of 5-8 m/s is observed along the southwestern coast of Japan.

• Journal of the Korean earth science society
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• v.30 no.6
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• pp.734-743
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• 2009

In order to examine how climatological condition can influence on urban scale particulate air pollutants, single and cross spectrum analysis have been performed to daily mean concentrations of particulate matters ($PM_{10}$) in Busan together with the climatological variables over the Asian dust source regions. Single power spectrum analysis of $PM_{10}$ concentrations in Busan shows that, aside from the typical and well-known periodicities, 3-4 year of peak periodicity of power spectrum density was identified. In cross spectrum analysis, this 3-4 year periodicity is found to have a strong positive correlation with the wind speed and pressure, and negative with the temperature and relative humidity, which is rather consistent with both characteristics of air mass during the Asian dust event whose periodicities have been recorded inter-annually over the Korean urban cities. Over the Asian dust source regions, $PM_{10}$ vs. precipitation shows no significant periodicity from the time series of precipitation data, but the periodicity of EDI (Effective Drought Index) shows some interannual variabilities ranging from 2 to 4 years over the various source regions, suggesting that, rather than precipitation itself, the EDI could be more closely associated with the occurrence frequency of Asian dust and interannual variability of urban particle concentrations in Korean cities.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.604-614
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• 2004

Using three-components geomagnetic data from a permanent geomagnetic observatory in Icheon, we have computed the power spectrum of each geomagnetic component, amplitude, phase and estimation error of transfer function for each day in the 6 months period July 2002${\sim}$December 2002. The temporal variation of power spectrum have random appearances with repeating relative strong and weak magnitude, which is considered as solar activities. However, there is no clear long-term trend. In the case of amplitude, phase and error of transfer function, even though there are some random patterns over the periods of 1000 s and under 100 s, they seem to be comparatively stable without manifest temporal changes. Futhermore, we have estimated electrical field by assuming P$_{1}\;^{0}$ spherical harmonics and then calculated the approximated apparent resistivity for each day. As a result, the variations of resistivity depend on the temporal magnitude of spectral power in horizontal magnetic fields rather than hydrological changes in near surface.

• Physical Therapy Korea
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• v.6 no.2
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• pp.77-86
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• 1999

Developmental dysplasia or dislocation of the hip is the most pronounced form of a condition in which the femoral heads tends progressively to leave the acetabulum. In the young child the variability of findings and course suggest a spectrum of conditions in which there are a number of common features: restriction of movement, particularly of abduction in flexion; shortening; and abnormal radiology, including a sloping or dysplastic acetabulum and delay in the appearance of the upper femoral epiphysis. It is vital to make the diagnosis of a congenital dislocation as soon after birth as possible. Conservative treatment with an abduction brace before the child run begins to walk is completely adequate, but after the age of 4 even surgical repositioning is difficult and after the age of 7 it is almost impossible. The aim of the study was to gain insight into the value of physical therapy of developmental dysplasia or dislocation after operation.

• Journal of Forest and Environmental Science
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• v.35 no.3
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• pp.141-149
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• 2019

Nanocellulose, which can exist as either cellulose nanocrystals or cellulose nanofibrils, has been used as a biomaterial for drug delivery owing to its non-immunogenicity, biocompatibility, high specific area, good mechanical properties, and variability for chemical modification. Various water-soluble drugs can be bound to and released from nanocelluloses through electrostatic interactions. The high specific surface area of nanocellulose allows for high specific drug loading. Additionally, a broad spectrum of drugs can bind to nanocellulose after facile chemical modifications of its surface. Controlled release can be achieved for various pharmaceuticals when the nanocellulose surface is chemically modified or physically formulated in an adequate manner. This review summarizes the potential applications of nanocelluloses in drug delivery according to published studies on drug delivery systems.