• Journal of The Korean Astronomical Society
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• v.56 no.2
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• pp.195-199
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• 2023

This paper is written as a follow-up observations to reinterpret the radial velocity (RV) of HD 36384, where the existence of planetary systems is known to be ambiguous. In giants, it is, in general, difficult to distinguish the signals of planetary companions from those of stellar activities. Thus, known exoplanetary giant hosts are relatively rare. We, for many years, have obtained RV data in evolved stars using the high-resolution, fiber-fed Bohyunsan Observatory Echelle Spectrograph (BOES) at the Bohyunsan Optical Astronomy Observatory (BOAO). Here, we report the results of RV variations in the M giant HD 36384. We have found two significant periods of 586 d and 490 d. Considering the orbital stability, it is impossible to have two planets at so close orbits. To determine the nature of the RV variability variations, we analyze the HIPPARCOS photometric data, some indicators of stellar activities, and line profiles. A significant period of 580 d was revealed in the HIPPARCOS photometry. H_α EW variations also show a meaningful period of 582 d. Thus, the period of 586 d may be closely related to the rotational modulations and/or stellar pulsations. On the other hand, the other significant period of 490 d is interpreted as the result of the orbiting companion. Our orbital fit suggests that the companion was a planetary mass of 6.6 M_J and is located at 1.3 AU from the host.

• Journal of the Korea Society of Computer and Information
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• v.4 no.1
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• pp.15-20
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• 1999

In this paper, we propose some essential requirements for CBM(Computer Based Multimedia) based distance education. This is a class of multimedia distance education in which the multimedia technique is combined with the distance home education application that is real time collaborative application on cyber-space using the information super highway. Requirements in this paper is observed standard at ITU(International Telecommunication Union). international standardization organization for multimedia communication. And. a structure for integrated home information service on the information super highway is based on IEEE 1394 serial communication and POF(Plastic Optical Fiber) home backbone that is study for application service according to the multimedia based distance home study system.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.328-338
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• 2001

Horizontal tunnel face reinforcement using Fiber Glass Tube(FGT) or steel pipe and pipe roofing techniques are frequently used when the stability of newly excavated tunnel is not guaranteed. However, the mechanical behavior of tunnels using these techniques has not been fully understood so far. Therefore, engineering rule of thumb is commonly applied during designing procedure, and it is difficult to adopt these techniques rationally. In this study, the application of a simplified numerical analysis method based on composite mechanics is verified. The mean field theory and the strain energy theory are used to obtain the equivalence elastic moduli of reinforced soil and rock. Furthermore, a parametric study on the deformational behavior of tunnel face is performed for various patterns of prereinforcement.

• Journal of the Korean Society of Safety
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• v.29 no.5
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• pp.7-14
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• 2014

This study aimed to develop members with the optimum impact characteristics to ensure a protected space for passengers in the case of automobile collisions. Accordingly, these members were fabricated to provide sufficient rigidity and safety to the passenger room structure and to absorb large amounts of energy during collision. In particular, CFRP members were fabricated with different section shapes such as square and single- and double-hat shapes. Next, their impact collapse characteristics and collapse modes were quantitatively analyzed according to the changes in section shapes and stacking angles. This analysis was performed to obtain design data that can be applied in the development of optimum lightweight members for automobiles.

• International Journal of Automotive Technology
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• v.7 no.5
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• pp.555-564
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• 2006

The aim of this paper is to contribute to the efficient design of traffic light poles involved in vehicle frontal collisions by developing a computer-based, finite-element model capable of capturing the impact characteristics. This is achieved by using the available non-linear dynamic analysis software "LS-DYNA3D", which can accurately predict the dynamic response of both the vehicle and the traffic light pole. The fiber reinforced polymer(FRP) as a new pole's material is proposed in this paper to increase energy absorption capabilities in the case of a traffic pole involved in a vehicle head-on collision. Numerical analyses are conducted to evaluate the effects of key parameters on the response of the pole embedded in soil when impacted by vehicles, including: soil type(clay and sand) and pole material type(FRP and steel). It is demonstrated from the numerical analysis that the FRP pole-soil system has favorable advantages over steel poles, where the FRP pole absorbed vehicle impact energy in a smoother behavior, which leads to smoother acceleration pulse and less deformation of the vehicle than those encountered with steel poles. Also, it was observed that clayey soil brings a slightly more resistance than sandy soil which helps reducing pole movement at ground level. Finally, FRP pole system provides more energy absorbing leading to protection during minor impacts and under service loading, and remain flexible enough to avoid influencing vehicle occupants, thus reducing fatalities and injuries resulting from the crash.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.461-464
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• 2008

This study investigated mechanical properties of the concrete using standard contents which was existent fibers in korea to apply the method for reducing crack of the non-reinforced concrete for the public space of an apartment with a fiber reinforcement. Results were summarized as following. The slump was slightly declined corresponding to the increase of the surface area and bridge effect of the fibers. For properties of the hardened concrete, the compressive strength was slighty reduced caused by the decrease of bonding strength between fiber and cement paste. The tensile strength was little increased according to bridge effect of the fibers, and the flexible strength and length change due to the drying shrinkage did not showed remarkable tendency.

• Publications of The Korean Astronomical Society
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• v.19 no.1
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• pp.101-107
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• 2004

This paper describes the digital back-end system for getting the data to analyze the user observation mode by digitalize the analog data after receiving the space radio using the radio telescope, The received analog data will be digitalized by high-speed sampler with 1 Gsps for 4 channel frequency band of millimeter wave, and the digital data will be transported through the fiber-optic digital transmission system and WDM(wavelength division multiplex) to observation building, The wideband digital FIR(Finite Impulse Response) filters analyze the data for user observation mode to record the data in high-speed recorder with 1 Gbps. In this paper, we introduce the overall system configuration and features combined by various information and communication technology in radio astronomy briefly, which will be adopted by KVN(Korean VLBI Network).

• Textile Coloration and Finishing
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• v.11 no.1
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• pp.34-41
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• 1999

To examine the increase of paper strength by solvent-bonding using N-methylmorpholine N-oxide (NMMO), a paper was treated with aqueous solutions of NMMO, concentrated at $90^\circ{C}$ for selected periods of time, and pressed for 5 seconds followed by washing and drying. The effect of the increasing NMMO concentration on bonding state and some important properties of samples were mainly investigated. With increasing concentration of NMMO, the degree of bonding between fibers was increased, the fiber cross-sectional shape was changed from 'thin ribbonlike' to 'round rodlike' by swelling with solvent, and the longitudinal waves (crimp) were introduced to fibers, hence the shrinkage, weight per unit area, and thickness of paper were increased. Consequently, the tensile strength and elongation, under standard and wet conditions, and the stiffness were increased, and the water absorption was decreased generally with increasing concentration of NMMO. The moisture regain of treated samples was lower than that of the untreated sample, because of the reduction of space between fibers. But the moisture regain was increased a little with increasing concentration of NMMO due to the fiber swelling with NMMO followed by structural relaxation.

• Applied Microscopy
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• v.44 no.3
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• pp.88-95
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• 2014

This study examined the effects of quercetin on corneal opacity caused by corneal edema by suppressing the damage on corneal endothelial cell, which was induced by mitomycin-C (MMC). In the MMC-treated group, the number of keratocytes was noticeably fewer compared to that of other groups. Although this group showed normal amount of fiber in the corneal stroma, the thickness was shown to be very thick and the alignment of the corneal endothelial cells that worked as the barrier against aqueous humor was irregular. According to such results, it was known that corneal opacity induced by MMC is not caused by proliferation of keratocytes, but by corneal edema triggered by the infiltration of aqueous humor. In the MMC+quercetin and quercetin+MMC-treated groups, the number of keratocytes was higher and polymorphonuclear leukocytes infilteration was lower significantly compared to that of the MMC-treated group. Although the amounts of fiber and endothelioid cell arrangement were normal, there was more space observed in the corneal stroma. Nonetheless, these groups showed significantly lower stromal thickness compared to that of the MMC group. In conclusion, quercetin has the effect on the reduction of corneal opacity caused by corneal edema that work MMC-induced damage to the corneal endothelial cells.

• Advances in concrete construction
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• v.10 no.2
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• pp.105-111
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• 2020

In this study eleven beam of steel fibre-reinforced concrete were tested on concentrated load in order to evaluate the shear strength and deformation of the beams after burning. Variables considered in the test include spaces of shear reinforcement (stirrups) and temperature (normal temperature at 38℃, 300℃, 600℃ and 900℃). The steel fiber used is set at 0.5% of the concrete volume. The phenomenon of the test results shows that although the beams were tested to achieve shear failure, the fact that all the tested beams did not encounter any shear failure. It has shown the influence of steel fibers and stirrups that plays a role in determining the mode of collapse. The concrete shear capacity of steel fibrous concrete beams installed with stirrups in altered spacing variations is not significantly different from each other, while beam deformability increases when the space stirrups are reduced. Furthermore, models of the developed-steel fibrous shear strength are compared and discussed with experimental results.