• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.101.2-101.2
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• 2012

An asteroid family is a population of asteroids in the proper orbital element space (a, e, i), considered to have been produced by a disruption of a large parent body presumably through a catastrophic collision. Asteroid families offer unique opportunities to reconstruct and characterize the break-up history of airless bodies in the main-belt. The Maria family is a typical old population (~3${\pm}$1 Gyr) of asteroids that have undergone significant collisional and dynamical evolution in the history of the inner Solar System; it is also believed to be one of the candidate source regions for giant S-type near-earth asteroids (NEAs). However, to date, physical characteristics of this family members such as rotational periods have been known only for 61 of the larger asteroids among 3,230 objects, which accounts for less than 2 percent of the family. In this presentation, we provide some preliminary results of our recent study: out of more than dozen of the family members, lightcurves for eight objects have been obtained for the first time. We plan to increase the number of target objects, and investigate evidences for the Yarkovsky/YORP effect on Maria family based on our observations.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.51.2-51.2
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• 2018

Polarimetry is a powerful technique to investigate the physical properties of surface materials on airless bodies in the solar system. It is known that the degree of linear polarization changes as a function of the phase angle (the angle between Sun-target-Observer). Especially, the dependency of the polarization degree at large phase angle allows us to obtain information related to the particle size and porosity, which is difficult to be determined via other observation techniques (i.e., photometry and spectroscopy). However, despite the advantage, only a few asteroids were observed with polarimetric devices at large phase angles. Here, we present our new polarimetric research of Near-Earth Asteroids (NEAs) observed at the large phase angles. Among the NEAs, we focus on S- and Q-type asteroids, which include: (331471) 1984 QY1, (90075) 2002 VU94, and (66391) 1999 KW4. The observation was conducted using the Pirka 1.6-m Telescope at the Nayoro Observatory of Hokkaido University at the phase angles ${\alpha}{\sim}100degree$, which provides us the maximum polarization degrees of these objects. Considering the observational results together with two objects ((1566) Icarus and (4179) Toutatis) in reference papers [1], [2], we will discuss the implication of the regolith size on their surfaces.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.41-42
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• 2012

High temperature / high pressure spray equipment using a conventional method, unlike spray polyurea adjustable pot life and yellowing caused by UV light and chemicals do not occur, or discoloration of Self-Leveling Type of rugged hand-polyurea resin for technology development is underway. This new concept of polyurea resin roller, brush, airless spray, and they installed easily using the unfamiliar labor, and curing time of approximately four hours to gain control of the glass because it is Pot. Construction, but does not like the spray polyurea resin, compared to the existing degradation of the adhesion strength is concerned. In this study, Self-Leveling Type Manual of polyurea resin adhesion strength of target deterioration Let's minimize problems by reviewing existing domestic and infrastructure long-term durability for long life of the facility is to obtain.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.8
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• pp.719-724
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• 2011

A Non_Pneumatic tire (NPT) has spoke to replace air of the pneumatic tires. A NPT appears to have advantages over the conventional pneumatic tire in terms of flat proof and maintenance free. And a NPT can also be used in the space environment since it uses no air for inflation. In this study, the static contact pressure of NPTs with auxetic honeycomb spokes is investigated as a function of vertical loading and is compared with that of a pneumatic tire. The finite element based numerical simulation of the local stress of an airless tire is carried out with ABAQUS for varying vertical force and honeycomb spokes geometries.

• Journal of Chest Surgery
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• v.29 no.6
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• pp.621-625
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• 1996

"Middle lobe syndrome" which was described y Graham and associates at first is always caused by ex- ternal bronchial compression by Iymph nodes. Although the patients may not present any symptom, the most common presenting symptoms were cough, dyspnea, fever, hemoptysis, and chest pain. Diagnostic procedures includ chest X-ray bronchoscopy, brochography, chest CT, and the principal finding is the contracted middle lobe which is usually airless. We experienced fifteen cases of middle lobe syndrome from April 1990 to May 1995. Eleven patients were treated surgically. The surgical candidates for middle lobe syndrome are suspicious malignancy, fixed bronchiectasis, bronchostenosis, intractable to medical treatment, recurrent infection. Operations were right middle lobectomy (8), right middle and lower bilobectomy (2), right upper and middle bilobectomy (1). Postoperative histological findings were tuberculosis in six, chronic inflammation in three, malignancy in one, and focal hemorrhage in one. There were two cases of postoperat ve complications which were postoperative atelectasis and hepatopathy.patopathy.