• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.175-178
• /
• 2015

Due to the lack of an accretion disk in a polar (magnetic cataclysmic variable, MCV), the material transferred from the secondary is directly accreted onto the white dwarf, forming an accretion stream and a hot spot on the white-dwarf component. During the eclipses, different light components can be isolated. Therefore, the monitoring of eclipsing polars could provide valuable information on several modern astrophysical problems, e.g., CVs as planetary hosting stars, mass transfer and mass accretion in CVs, and the magnetic activity of the most rapidly rotating cool dwarfs. In the past five years, we have monitored about 10 eclipsing polars (e.g., DP Leo and HU Aqr) using several 2-m class telescopes and about 100 eclipse profiles were obtained. In this paper, we will introduce the progress of our research group at YNOs. The first direct evidence of variable mass transfer in a CV is obtained and we show that it is the dark-spot activity that causes the mass transfer in CVs. Magnetic activity cycles of the cool secondary were detected and we show that the variable mass transfer is not caused by magnetic activity cycles. These results will shed light on the structure and evolution of close binary stars (e.g., CVs and Algols).

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.447-449
• /
• 2015

Although the link between activity in the nuclei of galaxy and galactic mergers has been under scrutiny for several years, it is still unclear to what extent and for which populations of active galaxies merger-triggered activity is relevant. The environments of AGN allow an indirect probe of the past merger history and future merger probability of these systems, suffering less from sensitivity issues when extended to higher redshifts than traditional morphological studies of AGN host galaxies. Here we present results from our investigation of the environment of radio selected sources out to a redshift z=2. We employ the first data release J-band catalog of the new near-IR Infrared Medium-Deep Survey (IMS), 1.4 GHz radio data from the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey and a deep dedicated VLA survey of the VIMOS field, covering a combined total of 20 sq. degrees. At a flux limit of the combined radio catalog of 0.1 mJy, we probe over 8 orders of magnitude of radio luminosity. Using the second closest neighbor density parameters, we test whether active galaxies inhabit denser environments. We find evidence for a sub-population of radio-selected AGN that reside in significantly overdense environments at small scales, although we do not find significant overdensities for the bulk of our sample. We show that radio-AGN in the most underdense environments have vigorous ongoing star formation. We interpret these results in terms of the triggering and fuelling mechanism of radio-AGN.

• Asian Journal of Turfgrass Science
• /
• v.2 no.1
• /
• pp.5-30
• /
• 1988

The object of this experiments was to know the salt tolerance of Fults and other lawn grasses. Fults, Olympic (Tall fescue, Festuca arundinacea Schred), Ceeping red fescue, Kentucky bluegrass and Zoysia grass (Z. japonica S.) were grown in hydroponics with vermiculite at various concentrations of NaCl. Hoagland's solution was used as the basic solution (control), and the concentrations of Cl to it were 1000, 2000, 3000, 4000 and l5OOOppm, respectively. Each was cultivated under the circumstances during 2 months. The results obtained are summarized as follows: 1.The growth of Fults, Olympic, Creeping red fescue and others were better at Cl lOOOppm than control. In the 5OOOppm application, Fescues become worse and 23.9% of them were withered. In concentration of Cl above 9OOOppm, it was impossible to live. 2.In the l0000~l1000ppm application, Olympic and Kentucky bluegrass were become worse and most of them died. 3.Fults were almost possible to live in the below of 9OOOppm, but they began to die in the above of 10000 ppm. 4.With the increasing concentration of Cl, plants were dwarfed and the number of stems, leaves and roots were reduced, but it was especially observed that the number of stolons of Creeping red fescue were increased at 1000~4000ppm. 5.Fults grass was the most salt tolerant turfgrass, but was impossible to live at salt level of about 36 millimhos (Exchange NaCI conductivity-ppm). Among the grasses, according to salt tolerance, they were arranged as follows. Fults > Zoysia japonica S. > Ky belugrass > Olympic grass > Creeping red fescue 6.The number of leaves, stems, tillers, and dry weight of Olympic grass, Fults and others were increased more at Cl 1OOOppm application than control, but in the above 4OOOppm application, those of plants were decreased. 7.The productivity of all grasses under the experiments was increased at 3.l75millimhos (Exchange NaCi conductivity ppm) in the concentration of Cl. The each dry-weight of Olympic, Creeping red fescue, Kentucky bluegrass and Zoysia grass was decreased at 8.85millimhos, and the weight of Fults grass was also decreased remarkably at 12.20millimhos. 8.As the result of this experiments, most plants grow normally at low concentration of NaCI-l000ppm. That seems to stimulate more the grasses to grow than non-salt.

• Journal of Magnetics
• /
• v.7 no.2
• /
• pp.45-50
• /
• 2002

A magnetic field annealing is firstly used for nanostructured Sm-Co/Co films, prepared by magnetron sputtering method. The effects of magnetic field annealing on single-layered Sm-Co films are different from those on multi-layered Sm-Co/Co films. A detailed analysis of microstructures and magnetic properties is made by means of HRTEM, Auger electron spectroscopy, XRD and Physical Property Measurement System (PPMS). From magnetic properties and microstructure analysis, it was confirmed that these differences originate from the effects of magnetic field annealing on crystallization behavior of the films. The relationship between magnetic properties and microstructures explains a different demagnetization process of single-layered and multilayered films. For the single-layered Sm-Co films, magnetic-field-annealing makes the main phases change from $CaCu_5/ to Zn_2Th_{17}$ structure, resulting in a decrease of coercivity. The results show that the magnetic-field-annealing is useful to improve the properties of nanostructured Sm-Co(30 nm)/Co(10 nm) films, which ascribe to improving the pinning effectiveness in coercivity mechanism and decreasing the magnetostatic interaction of films. A very high coercivity about 0.7 T was obtained from nanoscaled multi-layered Sm-Co(30 nm)-/Co(10 nm) films.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.4B
• /
• pp.378-385
• /
• 2011

The three-dimensional triangulation algorithm that the beacon nodes can be allocated to dynamically in not the experimental region but the practical region is suggested, and the performance of the localization system adapting the suggested algorithm is analyzed. The suggested algorithm adapts the computation method of the three dimensional point that the surfaces of three spheres overlapped, while the traditional triangulation algorithm adapts the computation method of the two dimensional point that three circles are overlapped in order to compute the distance between beacon nodes and mobile node that means a radius. In addition to this, to analyze the performance of the localization system adapting the suggested algorithm, first of all, the allocation layout of beacon nodes is made, and the allocation layout is modeled by selection of ten random distance values between mobile node and beacon nodes for computer simulation of the practical model. Next, the two dimensional coordinator of mobile node that is calculated by the suggested algorithm and the traditional triangulation algorithm is compared with each other. The localization measuring performance about three dimensional coordinator(z axis) of the suggested algorithm is also obtained by comparing with that of the practical model.

• Journal of Ocean Engineering and Technology
• /
• v.28 no.3
• /
• pp.236-244
• /
• 2014

This study considered a seagrass habitat in order to analyze the characteristics of a marine environment of seagrass located in the Seomjin river estuary, through an analysis of the distribution of the water depth, field observation, and three-dimensional numerical experiments using an EFDC model. The seagrass habitat was usually distributed at D.L(-) 0.5~0.0 m, and was hardly seen in the intertidal zone higher than that range. The distribution of the water temperature was within the range of $7.0{\sim}23.2^{\circ}C$, and the seagrass was demonstrated to have a strong tolerance to changes in the water temperature. In addition, the salinity distribution was found to be 27.2~31.0 psu, with suspended solids of 32.1 mg/L, which were higher than the previous research results (Huh et al., 1998), implying that there may be a reduction in the amount of deposits caused by the suspended solids. As for the sedimentary facies, they were comprised of 62.7% sand, 19.1% silt, and 18.2% clay, indicating that the arenaceous was superior and the sedimentary facies were similar to that of Dadae Bay. According to a numerical experiment, the maximum tidal current was 75 cm/s, while the tidal residual current was 10 cm/s, confirming that it sufficiently adapted to strong tidal currents. The erosion and deposition are predicted to be less than 1.0 cm/year. Thus, it is judged that the resuspension of sediments due to tidal currents and the changes in sedimentary facies are insignificant.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.10
• /
• pp.79-83
• /
• 1971

To investigate the effects of seed treatments and liming on nodulation and growth of lucerne(Medicago sativa L.) in an upland yellow-brown earth in N.Z. the five levels of seed treatments(Uninoculated, Inoculated, Inoculated plus lime pelleted, Inoculated plus 50/50 phosphate/dolmite pelleted, Inoculated plus ta1c pelleted), and 2 levels of lime applications (0, 25kg/10a) were compared and their interactions were observed, and then the following results were obtained. 1. In oder to obtain the effective nodulation of lucerne on acid soil it is usually necessary to apply lime and inoculate the seed. 2. The coating of inoculated lucerne seed with adequate materials will promote the nodulation. 3. The pelleting of lucerne seed may be a of reducing the need for the heavy liming. 4. The finely grounded lime was the best to use origin upland yellow-brown earth. 5. When the seed were not inoculated or pelleted with inferior material, liming is very effective for the nodulation and growth of lucerne. 6. The pelleting seed will reduce the laborious work and expenditure.

• Nuclear Engineering and Technology
• /
• v.52 no.1
• /
• pp.1-13
• /
• 2020

At present, the Department of Energy (DOE) in Unite State are directing the efforts of developing accident tolerant fuel (ATF) technology. As the first barrier of nuclear fuel system, the material selection of fuel rod cladding for ATFs is a basic but very significant issue for the development of this concept. The advanced cladding is attractive for providing much stronger oxidation resistance and better in-pile behavior under sever accident conditions (such as SBO, LOCA) for giving more coping time and, of course, at least an equivalent performance under normal condition. In recent years, many researches on in-plie or out-pile physical properties of some suggested cladding materials have been conducted to solve this material selection problem. Base on published literatures, this paper introduced relevant research backgrounds, objectives, research institutions and their progresses on several main potential claddings include triplex SiC, FeCrAl and MAX phase material Ti3SiC2. The physical properties of these claddings for their application in ATF area are also reviewed in thermohydraulic and mechanical view for better understanding and simulating the behaviors of these new claddings. While most of important data are available from publications, there are still many relevant properties are lacking for the evaluations.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.19 no.2
• /
• pp.304-314
• /
• 2005

The major concept of Sasang typology is that the disease susceptibility and drug response as well as physiological characteristics are presumed to be different depending on their Sasang types. Although characterizing fundamental basis of their traits are crucial in this research field, only pathological susceptibility and physical appearances were thoroughly studied. We evaluated their physiological characteristics by tapping psychological, physical and genetic traits of each Sasang types. After determining the Sasang type of one hundred three college students based on the Questionnaire for the Sasang Constitution Classification, the psychological, physical and genetic traits of each type were analyzed with the Myers-Briggs Type Indicator (MBTI), Bioelectrical Impedance Analysis and genetic polymorphism test, respectively. Each of the Sasang types showed significantly different profiles (Generalized estimation equation, coef=11.88, z=2.13, p=0.033), and could be distinctively classified based on their MBTI scores (discriminant analysis Wilks Lambda=0.611, df=8, chi-square=36.7, p<0.001). Subjects with the So-Eum type (Introversion and Judging) and the So-Yang type (Extroversion and Perceiving) showed contrasting psychological features, however they had similar anthropometric characteristics. Subjects with the Tae-Eum type showed bigger Body Mass Index ($R^2$=0.22, df=4, 74, F=5.07, p=0.001) and body shape compared to others. Although there were no significant differences in G-protein beta-3 subunit polymorphism, angiotensin-converting enzyme polymorphism and Methylenetetrahydrofolate reductase polymprhisms among groups with Sasang types, it was shown that the dopamine system could be one for genetic marker for Sasang typology. These results demonstrated distinctive and essential traits of Sasang typology using reproducible psychometric, anthropometric and genetic evaluations. We also found that the Sasang typology was a bio-psychological typology which could show trait-specific guideline for individualized medicine.

• Restorative Dentistry and Endodontics
• /
• v.21 no.2
• /
• pp.585-601
• /
• 1996

The purpose of this study was to elucidate the effect of blood-and saliva-contamination during dentin pretreatment procedure on tensile bond strength, and to investigate the effect of contaminant-removing treatments on the recovery of bond strength of dentin bonding agents. Dentin specimens prepared from freshly extracted bovine mandibular anterior teeth were divided into non-contaminated control and contaminated experimental groups. The specimens of the contaminated group were contaminated with saliva or blood after etching or priming procedure, followed by contaminant-removing treatments. All the specimens were bonded with All Bond$^{(R)}$ 2 dentin bonding agent and Bisfil$^{TM}$ composite resin or Scotchbond$^{TM}$ Multipurpose and Z100. After all the bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, tensile bond strengths were measured. The contaminated dentin and fractured dentin surfaces were examined under the scanning electron microscope. The results were as follows : Contaminated specimens showed lower bond strength than non-contaminated ones regardless of the kind of contaminant, contamination time and contaminant-removing treatments, except specimens which were acid-etched following saliva contamination after etching in All Bond$^{(R)}$ 2 groups (p<0.05). Blood contaminant resulted in much bond strength decrease than saliva ones (p<0.01), and contamination after priming resulted in much decrease in bond strength than after etching (p<0.01). Re-etching resulted in increase of bond strength in the specimens contaminated with saliva after etching but not in blood contaminated ones. Re-priming resulted in increase of bond strength in the specimens contaminated after priming regardless of the kind of contaminant.