• Journal of Astronomy and Space Sciences
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• v.29 no.1
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• pp.51-55
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• 2012

A few high-mass X-ray binaries-consisting of an OB star plus compact companion-have been observed by Fermi and ground-based Cerenkov telescopes like High Energy Stereoscopic System (HESS) to be sources of very high energy (VHE; up to 30 TeV) ${\gamma}$-rays. This paper focuses on the prominent ${\gamma}$-ray source, LS 5039, which consists of a massive O6.5V star in a 3.9-day-period, mildly elliptical ($e{\approx}0.24$) orbit with its companion, assumed here to be an unmagnetized compact object (e.g., black hole). Using three dimensional smoothed particle hydrodynamics simulations of the Bondi-Hoyle accretion of the O-star wind onto the companion, we find that the orbital phase variation of the accretion follows very closely the simple Bondi-Hoyle-Lyttleton (BHL) rate for the local radius and wind speed. Moreover, a simple model, wherein intrinsic emission of ${\gamma}$-rays is assumed to track this accretion rate, reproduces quite well Fermi observations of the phase variation of ${\gamma}$-rays in the energy range 0.1-10 GeV. However for the VHE (0.1-30 TeV) radiation observed by the HESS Cerenkov telescope, it is important to account also for photon-photon interactions between the ${\gamma}$-rays and the stellar optical/UV radiation, which effectively attenuates much of the strong emission near periastron. When this is included, we find that this simple BHL accretion model also quite naturally fits the HESS light curve, thus making it a strong alternative to the pulsar-wind-shock models commonly invoked to explain such VHE ${\gamma}$-ray emission in massive-star binaries.

• Nuclear Engineering and Technology
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• v.52 no.6
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• pp.1259-1265
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• 2020

A beta ray scanner was proposed for in-situ discrimination of beta and gamma ray radioactivity. This scanner is based on the principle that gamma and beta rays experience different changes in detection efficiency in scintillators with different geometries, especially with regard to the scintillator thickness. The ratios of the counting rates of gamma rays (R_gamma), beta rays (R_beta), and sample measurements (R_total) in a thick scintillator to those in a thin one are reported. The parameter X_thick, which represents the counting rate contributed by beta rays to the total counting rate in the thick scintillator, was derived as a function of those ratios. The values of R_gamma and R_beta for ⁶⁰Co and ⁹⁰Sr sources were estimated as 3.2 ± 0.057 and 0.99 ± 0.0049, respectively. The estimated beta ray contributions had relative standard deviations of 2.05-4.96%. The estimated range of the beta rays emitted from ⁹⁰Sr was 19 mm as per the Monte Carlo N-Particle simulation, and this value was experimentally verified. Homogeneous and surface contaminations of ⁶⁰Co and ⁹⁰Sr-⁹⁰Y were simulated for application of the proposed method. The counting rate contributed by the beta rays was derived and found to be proportional to the concentration of ⁹⁰Sr-⁹⁰Y contamination.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.5
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• pp.298-303
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• 2005

This study described the reproductive behavior and the morphological development of the larvae and juvenile of the hedgehog seahorse (Hippocampus spinosissimus). Larvae released from male seahorse were reared for 30 days in the laboratory. At the birth, the small flap-like mouth and anus of the yolk-sac larvae were open, and the yolk was completely absorbed within 1 day. The size of newborn larvae ranged 7.01-13.19mm (mean $9.26\pm1.9mm$, n=9) in TL (total length). The larvae had 15-16 pectoral fin rays and 19 dorsal fin rays, but 4 anal fin rays were not completely developed. The larval size ranged 13.38-14.38 mm (mean $13.96\pm0.3mm$, n=6) in TL at 1 day after release, and they had 17 pectoral fin rays, 20 dorsal fin rays and 4 anal fin rays when the larvae reached the juvenile stage. Juvenile size ranged 14.98-16.42mm (mean $15.84\pm0.5mm$, n=5) in TL at 3 days after release, and 1, 4, 6, 8 trunk spines extended quickly. Terminal part of the coronet became a four-forked wedge shape concurrently. Juvenile became 23.25mm (n=l) in TL after 15 days and all 11 trunk rings was connected completely. After 20 days, the juveniles were 24.66-28.65mm (mean $27.26\pm1.6mm$, n=5) in TL, and many melanophores appeared in integument. In the eye lenses, 5-6 lusters were formed. After 30 days, the juveniles were 26.78-28.26 mm (mean $27.36\pm0mm$, n=4)in TL and 8-9 lusters appeared on the eye lenses. Coronet terminal part developed to a five-forked crown-shape completely.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.136-143
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• 2003

The eggs of Favonigobius gymnauchen attached on the under side of a small stone were collected off Seongsan-eup Cheju-do in August, 2000 to investigate their development of egg, larvae and juveniles. The fertilized eggs were elliptical in shape (mean long axis: 1.50 mm; mean short axis: 0.57 mm) and transparent. There were filaments on one side of the egg membrane. Larvae hatched at 48 hrs 50 mins after morula stage with 25-26 myotomes in $22.8-28.5^{\circ}C\;(mean\;24.7^{\circ}C).$ The newly hatched larvae were 2.31-2.49 mm (mean 2.37 mm n=10) in total length (TL) and their mouth and anus were already opened. Their melanophores were appeared on the over gas globule, around anus and the part of caudal peduncle with 24-25 myotomes. At 4-5 days after hatching. larvae attained 3.81-4.07 mm (mean 3.96 mm, n=10) in TL and their yolk sac was completely absorbed. They began to eat rotifer and transformed to postlarvae stage. At 14 days after hatching, postlarvae attained 6.17-6.31 mm (mean 6.21 mm, n=10) in TL and their caudal notocord was flexed $45^{\circ}$ upward. At 24 days after hatching, postlarvae attained 8.69-9.10 mm (mean 8.87 mm, n=10) in TL had reached the juvenile stage. All fins were formed with the complete set of fin rays with the following counts: dorsal fin rays IV-I, 9-10; anal fin rays I, 9; pectoral fin rays 17; ventral fin rays: I, 5; caudal fin rays: 9+8= 17.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.245-251
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• 2013

This study was conducted to compare quality characteristics of imported skate rays. The moisture content was higher in imported skate rays than in domestic mottled skate, while the protein content displayed a contrasting pattern. From measurements of the volatile basic nitrogen content, pH, viable cell counts, and urea and ammonia contents, the freshness of skate rays imported from Chile, Canada and Uruguay was considered to be inferior to domestic mottled skate, while the freshness of skate rays imported from the USA was similar. The measurement of physicochemical properties revealed that four kinds of imported skate rays were of inferior quality, as compared to domestic mottled skate.

• Journal of The Korean Society of Clinical Toxicology
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• v.11 no.2
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• pp.101-105
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• 2013

Purpose: This study was conducted in order to determine the relationship between the number of portable X-rays and the radiation exposure dose for emergency medical service providers working in the emergency department (ED). Methods: A prospective study was conducted from February 15, 2013 to May 15, 2013 in the ED in an urban hospital. Six residents, seven emergency medical technicians (EMT), and 24 nurses were enrolled. They wore a personal radiation dosimeter on their upper chest while working in the ED, and they stayed away from the portable X-ray unit at a distance of at least 1.8 m when the X-ray beam was generated. Results: The total number of portable x-rays was 2089. The average total radiation exposure dose of emergency medical service providers was $0.504{\pm}0.037$ mSv, and it was highest in the EMT group, 0.85(0.58-1.08) mSv. The average of the total number of portable X-rays was highest in the doctor group, 728.5(657.25-809). The relationship between the number of portable X-rays and the radiation exposure dose was not statistically significant(-0.186, p=0.269). Conclusion: Under the condition of staying away from the portable X-ray unit at a distance of least 1.8 m, the relationship between the number of portable X-rays and the radiation exposure dose was not statistically significant.

• Journal of the Korean Wood Science and Technology
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• v.22 no.4
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• pp.26-36
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• 1994

The comparative wood anatomy of 1 species belonging to genus Myrica of Myricaceae, 9 species to genus Populus and 8 species to genus Salix of Salcaceae, occurring in Korea, was described and coded according to IAWA list(Wheeler, 1989). Myrica rubra. of Myricaceae is a typical diffuse-porous wood with numerous vessels per $mm^2$ and its pores are mainly angular in outline. Vessels scalariform perforation plates with a few bars, very small inter vessel pits; axial parenchyma abundant, diffuse or diffuse-in-aggregates which is distinct and easily observed on cross section; rays 1-3 seriate, Kribs' heterogeneous I or II types, frequently contains rhomboidal crystals; Dark pigmented substances included in some rays and axial parenchyma. Salicaceae, a typical diffuse porous wood, has mainly radial pore multiple, large intervessel pits, distinct alternate pits, simple perforation plates, ray-vessel pits with circular large pits, uniseriate rays, marginal parenchyma composed of 1-2 layers. In some species, ray parenchyma contain crystals. Populus and Salix wood can be distinguished from one another by the following characters. Pores of Populus woods almost angular in outline. Uniseriate homogeneous rays slightly higher than Salix and long linear on tangential section. Whereas Salix woods appear the pores almost oval, uniseriate heterogeneous rays, which are smular narrow fusiform on tangential section and lower in height than Populus.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.752-759
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• 2018

The SBR technique is one of the asymptotic high frequency method, where a dense grid of rays are launched and traced to analyze the scattering properties of the target. In this paper, we propose an accelerated SBR technique using grouping a central ray and 8 surrounding rays around the center ray. First, launched rays are grouped into groups consisting of a central ray and 8 surrounding rays. After the central ray of each group is preferentially traced, 8 surrounding rays are rapidly traced using the information of ray tracing for the central ray. Simulation result of scattering analysis for CAD models verifies that the proposed method reduces the computational time without decreasing the accuracy.

• Journal of Radiation Protection and Research
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• v.44 no.2
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• pp.53-63
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• 2019

Background: As neutron fields are always accompanied by gamma rays, it is essential to distinguish neutrons from gamma rays in the detection of neutrons. Neutrons and gamma rays can be separated by pulse shape discrimination (PSD) methods. Recently, we performed characterization of a stilbene scintillator detector and an EJ-301 liquid scintillator detector with a high-speed digitizer DT5730 and investigated optimized PSD variables for both detectors. This study is for providing a basis for developing fast neutron/gamma-ray dual-particle imager. Materials and Methods: We conducted PSD experiments using stilbene scintillator and EJ-301 liquid scintillator and evaluated neutron and gamma ray discriminability of each PSD method with a $^{137}Cs$ gamma source and a $^{252}Cf$ neutron source. We implemented digital signal processing techniques to apply two PSD methods - the charge comparison (CC) method and the constant time discrimination (CTD) method - to distinguish neutrons from gamma rays. We tried to find optimized PSD variables giving the best discriminability in a given experimental condition. Results and Discussion: For the stilbene scintillator detector, the charge comparison method and the constant time discrimination method both delivered the PSD FOM values of 1.7. For the EJ-301 liquid scintillator detector, both PSD methods delivered the PSD FOM values of 1.79. With the same PSD variables, PSD performance was excellent in $300{\pm}100keVee$, $500{\pm}100keVee$, and $700{\pm}100keVee$ energy regions. This result shows that we can achieve an effective discrimination of neutrons from gamma rays using these scintillator detector systems. Conclusion: We applied both PSD methods to a stilbene and a liquid scintillator and optimized the PSD performance represented by FOM values. We observed a good separation performance of both scintillators combined with a high-speed digitizer and digital PSD. These results will provide reference values for the dual-particle imager we are developing, which can image both fast neutrons and gamma rays simultaneously.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.11a
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• pp.105-112
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• 2000

The conventional model did not take momentum conservation into consideration when the electron absorbs and emits the photons. II-ray provides momentum conservations on any directions of the entering photons, and also the electrons have radial momentum conservations and fully elastic bouncing between two atoms, in the new atom model. Conventional atom model must be criticized on the following four points. (1) Natural motions between positive and negative entities are not circular motions but linear going and returning ones, fur examples sexual motion, tidal motion, day and night etc. Because the radius of hydrogen atom's electron orbit is the order of 10$^{-11}$ m and the radia of the nucleons in the nucleus are the order of 10$^{-l4}$m and then the converging $\pi$-gamma rays to the nucleus have so great circular momentum, the electron can not have a circular motion. We can say without doubt that any elementary mass particle can have only linear motion, because of the $\pi$-rays' hindrances, near the nucleus. (2) Potential energy generation was neglected when electron changes its orbit from outer one to inner one. The h v is the kinetic energy of the photo-electron. The total energy difference between orbits comprises kinetic and potential energies. (3) The structure of the space must be taken into consideration because the properties of the electron do not change during the transition from outer orbit to inner one even though it produces photon. (4) Total energy conservation law applies to the energy flow between mind and matter because we daily experiences a interconnection between mind and body. Any magnet absorbs n-rays to S pole and sends out the $\pi$-rays from N pole. Proton are constructed with the closed n-rays quantum-mechanically. The crystallizing n-bonding makes two $\pi$-far infrared rays of one wave length between two protons if two $\pi$-rays are supplied to each proton. It is easily done for a $\pi$-ray to be absorbed to a proton if there is a parallel magnetic flow to the blood flow because a $\pi$-ray advances axially under a magnetic field and a proton looks like a sphere. A axially advancing disk-like $\pi$-ray can meet more easily the coming spheres than from the other directions. The blood crystals stimulate the autonomous nerves on the blood vessels during the flow by their mechanical sliding collisions. SM n-ray meridian therapy and SMACN $\pi$-ray meridian therapy show the stimulation of blood flow and also combinational experiment between SM $\pi$-ray meridian therapy and n-ray psycho-physics acupuncture shows more clearly that magnet is forcing to make $\pi$-rays absorbed to the nucleons.s.ons.