• Structural Engineering and Mechanics
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• v.60 no.5
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• pp.891-902
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• 2016

The beam structure with breathing cracks subjected to harmonic excitations was modeled by FEM based on Euler-Bernoulli theory, and a piecewise dynamical system was deduced. The precise integration method (PIM) was employed to propose an algorithm for analyzing the dynamic responses of the deduced system. This system was first divided into linear sub-systems, between which there are switching points resulted from the breathing cracks. The inhomogeneous terms due to the external excitations were tackled by introducing auxiliary variables to express the harmonic functions, hence the sub-systems are homogeneous. The PIM was then applied to solve the homogeneous sub-systems one by one. During the procedures, a predictor-corrector algorithm was presented to determine the switching points accurately. The presented method can provide solutions with an accuracy to a magnitude of $10^{-12}$ compared with exact solutions obtained by the theories of ordinary differential equations. The PIM results are much more accurate than Newmark ones with the same time step. Moreover, it is found that the PIM can maintain a high level of accuracy even when the time step increases within a relatively wide range.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.221-225
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• 2015

As metformin can inhibit endometrial carcinoma (EC) cell growth and the insulin growth factor (IGF) system is active in EC, the question of whether it can regulate endometrial carcinoma cell secretion of IGF-1 or expression of IGF-1 receptor (IGF-1R) is of interest. In this study, serum IGF-1 levels in EC patients were found to be comparable with that in the non EC patients (p>0.05). However, the IGF-1 level in the medium of cultured cells after treatment with metformin was decreased (p<0.05). IGF-1R was highly expressed in human endometrial carcinoma paraffin sections, but IGF-1R and phosphor-protein kinase B/protein kinase B (p-Akt/Akt) expression was down-regulated after metformin treatment (p<0.05). In summary, metformin can reduce the secretion of IGF-1 by Ishikawa and JEC EC cell lines and their expression of IGF-1R to deactivate downstream signaling involving the PI-3K/Akt pathway to inhibit endometrial carcinoma cell growth.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.329-332
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• 2007

Solar retinopathy is a rare but well-recognized clinical entity of macular damage, caused by viewing a solar eclipse or direct sun gazing. A 21-year-old man gazed at the sun for approximately thirty seconds at noon using a monocular telescope with his left eye. Forty-eight hours after sun gazing, the patient experienced symptoms of blurred vision and central scotoma in the left eye. Eight months after sun gazing, the visual acuity decreased from 1.0 to 0.1 in the left eye and the fundus examination showed a round, yellowish-white discoid lesion at the left fovea. Fluorescein angiography showed an early window defect in the fovea of the left eye, that persisted without size change during the late phase resulting from atrophy of the retinal pigment epithelium. A small, central scotoma of the left eye was also found in the visual field test. The visual acuity was unchanged at the end of a one-year follow-up period.

• Journal of Astronomy and Space Sciences
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• v.33 no.3
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• pp.237-246
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• 2016

We analyze the design and specifications of the Sun-and-Stars Time-Determining group of instruments (Ilseong-jeongsi-ui, 日星定時儀) made during the Joseon dynasty. According to the records of the Sejong Sillok (Veritable Records of King Sejong), Sun-and-Stars Time-Determining Instruments measure the solar time of day and the sidereal time of night through three rings and an alidade. One such instrument, the Simplified Time-Determining Instrument (So-jeongsi-ui, 小定時儀), is made without the essential component for alignment with the celestial north pole. Among this group of instruments, only two bronze Hundred-Interval-Ring Sundials (Baekgak-hwan-Ilgu, 百刻環日晷) currently exist. A comparison of the functions of these two relics with two Time-Determining Instruments suggests that the Hundred-Interval-Ring Sundial is a Simplified Sundial (So-ilyeong, 小日影), as recorded in the Sejong Sillok and the Seongjong Sillok (Veritable Records of King Seongjong). Furthermore, the Simplified Sundial is a model derived from the Simplified Time-Determining Instrument. During the King Sejong reign, the Sun-and-Stars Time-Determining Instruments were used in military camps of the kingdom's frontiers, in royal ancestral rituals, and in royal astronomical observatories.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.1
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• pp.110-115
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• 2004

This experiment was conducted to investigate the effect of light intensities on the growth responses, carbohydrate contents and the characteristics of leaf gas exchange in Miscanthus sinensis and Pennisetum purpurascens. The plant height and leaf length were increased to about 30% in the sun. However, those were reduced severely in the shade, and leaf necrosis was also observed. The representative growth index and the dry weight of 2 species were 50% higher than shade and the rate was reduced according to the decrease of light intensities. Total carbohydrate contents showed very similar changes to that of dry weight. However, any notable influences were observed at above the light intensities of 250~500${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ in the half shade. The size of spikes and the earliest spiking appeared in the sun and the spike color was decolorized as decreased in light intensities, irrespective of species. Photosynthetic rate of 2 species was 2 times higher in the sun than those in the shade, and it showed the typical photoresponses of sun plant. Stomatal conductances and intercelluar $CO_2$ concetration showed similar changes to that of photosynthetic rate. On the contrary, vapor pressure deficit was increased more in the shade than in the sun.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.379-381
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• 2008

본 논문에서는 도시의 소음문제와 기존 방음벽의 문제를 근본적으로 해결하기 위해서는 도시 생태계를 고려한 생태식생방음벽의 개발이 필요하며 이를 위해 시스템 및 소재개발, 설계 및 시공기술들을 개발이 필요하다. 방음벽의 소음의 저감을 위한 단순한 구조물차원을 벗어나 소음 저감 기능을 가지는 환경친화적인 녹화구조물로 개발될 필요가 있다. 이는 절대 녹지의 부족과 단절로 인해 파생되는 도시 생태적 문제를 적극적으로 해결할 수 있는 현실적인 대안이 될 수 있을 뿐만 아니라, 도시경관 및 운전자와 주민 정서의 순화에 크게 기여할 것으로 예상된다. 결론적으로, 도시생태환경에 악영향을 가져왔던 기존의 방음벽에 반해서, 도시 전체적으로 녹지의 확대와 더불어 경관의 향상, 생태계 복원 등 시너지 효과를 가져올 식생방음벽의 개발은 도시환경의 질적 개선을 위한 현실적인 대안으로 연구 개발이 필요하다고 판단된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.82-87
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• 2002

The attitude determination in LEO Satellite like KOMPSAT is one of the most important issues for Sun-Acquisition. Particularly, in KOMPSAT, the roll axis direction can be determined since the sun sensor gives the information on the Euler angle for pitch and yaw axes in Sun-Acquisition mode. In other words, it is the problem to determine the two unknown axes direction with one axis knowledge. This paper proposes a new effective method for attitude determination of general LEO satellites when one axis information is avilable and proves its usefulness throughout the simulation.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.3
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• pp.228-233
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• 1993

Method for the sun curing dehydration of pig excreta by using vinyl house was described. We determined effects of the dehydrated pig excreta on the yields of whole crop corn and proximate chemical composition of whole crop corn. Pig excreta were dehydrated upto 15% of moisture content by the 3-4 days of sun curing dehydration in vinyl house in the summer period. There was no significant difference between the dehydrated pig excreta treatment and the chemical fertilizer treatment on dry matter(DM) content, DM yield and crude protein contents of whole crop corn. Ca and Mg contents by the dehydrated pig excreta treatment were lower than those by thechemical fertilizer treatment. In the contrast, K content by the dehydrated pig excreta treatment was higher than those by the chemical fertilizer treatment. and dehydrated pig excreta treatments were higher in K/Ca+Mg ratio than chemical fertilizer treatment. These results suggested the availability of the sun curing dehydration of pig excreta in vinyl house in small-scale animal industry. In addition, the dehydrated pig excreta treatment showen similar effects to the chemical fertilizer treatment on dry matter yields and contents of chemical composition of whole crop corn. These results suggest that using the sun curing dehydration of pig excreta could reduce the chemical fertilizer cost. However, we need more study to the relationship between the unbalanced mineral contents and animal health.

• Journal of The Korean Astronomical Society
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• v.39 no.2
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• pp.51-56
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• 2006

We report the development of a semi-VLBI observation system operating at 21 cm and present the measurement of visibility function toward the sun using this system. The system consists of two 2.3 meter antennas with a maximum separation of 35 meter, a conventional high speed data acquisition system, and a set of programs for software correlation. Since two local oscillators of receiver modules are independent, data had to be fringe-fitted to yield the visibility amplitude. It is found that the visibility amplitude decreases and then bounces back as baseline increases. We confirm that solar disk with brighter limb best explains the measured visibility amplitude.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.267-270
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• 2017

As IT technology developed, storage media also developed. Among them, USB, which is a removable storage medium, is used not only to have several per person but also to work in various companies. Users store valuable and confidential data within USB. As time went on, the need for security increased. In order to solve this security problem, USB has been introduced to allow users to access internal files by inputting ID and password by embedding a security program in USB. However, the method of storing ID and Password inside is low confidentiality and high risk of information leakage. To solve these problems, we propose a 2 factor authentication system using Radius server in addition to login authentication. The proposed system not only improves the authenticity of the device, but also reduces the risk of infringement of personal information when lost. It also encrypts internal files to increase the confidentiality of internal information.