• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.261-263
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• 2004

We present a progress report on HCN(1-0) line observations toward starless cores to probe inward motions. We have made a single pointing survey toward the central regions of 85 starless cores and performed mapping observations of 6 infall candidate starless cores. The distributions of the velocity difference between HCN(1-0) hyperfine lines and the optically thin tracer $N_2H^+$(1-0) are significantly skewed to the blue, meaning that HCN(1-0) frequently detects inward motions. Their skewness to the blue is even greater than that of CS(2-1) Lee et al., possibly implying more infall occurrence than CS(1-0). We identify 19 infall candidates by using several characteristics illustrating spectral infall asymmetry seen in HCN(1-0) hyperfine lines, CS(3-2), CS(2-1), $DCO^+(2-1)$ and $N_2H^+$ observations. The HCN(1-0) F(O-l) with the least optical depth usually shows a similar intensity distribution to that of $N_2H^+$ which closely traces the density distribution of the cores, indicating that HCN(1-0) is less chemically affected and so believed to reflect kinematics occurring in rather inner regions of the cores. Detailed radiative transfer model fits of the spectra are underway to analyze central infall kinematics in starless cores.

• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.211-216
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• 2004

We present the results of an H I aperture synthesis mosaic of the Large Magellanic Cloud (LMC), made by combining data from 1344 separate pointing centers using the Australia Telescope Compact' Array (ATCA) and the Parkes multibeam receiver. The resolution of the mosaiced images is 50" (<15 pc, using a distance to the LMC of 55kpc). This mosaic, with a spatial resolution .15 times higher than that which had been previously obtained, emphasises the turbulent and fractal structure of the ISM on the small scale, resulting from the dynamical feedback of the star formation processes with the ISM. We also have done a widefield panoramic survey of H$\alpha$ emission from the Magellanic Clouds with an imager mounted on the 16-inch telescope at Siding Spring Observatory. This survey produced H$\alpha$ images which are equal to the ATCA survey in area coverage and resolution. This survey allows us to produce a continuum-subtracted image of the entire LMC. In contrast with its appearance in the H$\alpha$ image, the LMC is remarkably symmetric in H I on the largest scales, with the bulk of the H I residing in a disk of diameter 8. $^{\circ}4$ (7.3 kpc) and a spiral structure is clearly seen. The structure of the neutral atomic ISM in the LMC is dominated by H I filaments combined with numerous shells and holes.

• The Journal of Korea Robotics Society
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• v.15 no.3
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• pp.240-247
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• 2020

This paper presents a novel knitted data glove system for pattern classification of hand posture. Several experiments were conducted to confirm the performance of the knitted data glove. To find better sensor materials, the knitted data glove was fabricated with stainless-steel yarn and silver-plated yarn as representative conductive yarns, respectively. The result showed that the signal of the knitted data glove made of silver-plated yarn was more stable than that of stainless-steel yarn according as the measurement distance becomes longer. Also, the pattern classification was conducted for the performance verification of the data glove knitted using the silver-plated yarn. The average classification reached at 100% except for the pointing finger posture, and the overall classification accuracy of the knitted data glove was 98.3%. With these results, we expect that the knitted data glove is applied to various robot fields including the human-machine interface.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.251-253
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• 2004

Automated east/west and north/south station-keeping maneuvers were simulated for the geostationary COMS (Communication, Ocean and Meteorological Satellite) satellite that will be launched around year 2008, The satellite has to be maintained within ${\pm}0.05^{\circ}$ at the nominal longitude of $128.2^{\circ}\;E$. The general perturbation method was used to keep the position of the geostationary satellite. Weekly based east/west and biweekly based north/south station-keeping maneuvers were investigated. The sun pointing perigee control method and two-bum strategy were used for the east/west station-keeping maneuver. Switching the right ascension of the ascending node to descending node was adopted for the north/south station-keeping maneuver. One year station-keeping maneuver was demonstrated and various station-keeping orbital parameters were analyzed.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.2
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• pp.53-64
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• 2020

We provide one of the first investigation on the impact of the degree of total leverage to the dividend policy of bank. We use a large sample of US bank holding companies from 2000:Q1 to 2017:Q4 to shed light our research question. Our empirical analysis provides consistent evidence that banks with high degree of total leverage (i.e. banks with a relatively high fixed-to-variables costs) are less likely to pay dividends, and they spend a lower fraction of incomes to pay back shareholders, suggesting a higher conservatism in dividend policy of banks subject to high degree of total leverage. The evidence remains unchanged with alternative econometric approaches, alternative measures of dividend policy and degree of total leverage. We further document that this higher conservatism is strengthened for a sample of banks with low franchise value during the financial crises. Our result suggests that the conservatism in dividend policy of banks with high degree of total leverage seems to be related to the precautionary motives aimed at preserving corporate resources under financial distress. Our study contributes to the literature of cost structure and dividend policy by pointing out that the impacts of the degree of fixed-to-variable expenses to dividend policy are extended to the case of banks.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.34.1-34.1
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• 2013

The first generation stars in the universe are not observed as discrete objects by using current observational facilities, but their contributions are redshifted to the near infrared wavelength bands at present universe. Therefore, investigation of background radiation at near infrared is important for the study of the first stars. In this study, we present new observations of spatial fluctuations in sky brightness toward the north ecliptic pole using data from AKARI. Among pointed observation program of AKARI, we used two pointing surveys named Monitor field and NEP wide field at three wavelength bands 2.4, 3.2, and 4.1 ${\mu}m$. To obtain spatial fluctuations from observed images, first of all, we exclude pixels affected by resolved foreground objects and then obtain diffuse map which consists of diffused radiation only. Because the diffuse map contains not only cosmological components but also various foreground components, in order to detect cosmological components, we estimate the contributions of foreground components separately. The results of this study show that there remains excess spatial fluctuation that cannot be explained by known foreground sources. This work is based on observations with AKARI, a JAXA project with the participation of ESA.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.35.1-35.1
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• 2013

The first generation stars in the universe are not observed as discrete objects by using current observational facilities, but their contributions are redshifted to the near infrared wavelength bands at present universe. Therefore, investigation of background radiation at near infrared is important for the study of the first stars. In this study, we present new observations of spatial fluctuations in sky brightness toward the north ecliptic pole using data from AKARI. Among pointed observation program of AKARI, we used two pointing surveys named Monitor field and NEP wide field at three wavelength bands 2.4, 3.2, and 4.1 ${\mu}$. To obtain spatial fluctuations from observed images, first of all, we exclude pixels affected by resolved foreground objects and then obtain diffuse map which consists of diffused radiation only. Because the diffuse map contains not only cosmological components but also various foreground components, in order to detect cosmological components, we estimate the contributions of foreground components separately. The results of this study show that there remains excess spatial fluctuation that cannot be explained by known foreground sources. This work is based on observations with AKARI, a JAXA project with the participation of ESA.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.76.2-76.2
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• 2013

SPICA(SPace Infrared Telescope for Cosmology and Astrophysics) is an infrared space observatory with cooled telescope of 3 m aperture. Because of its large aperture, near- and mid-infrared instruments onboard SPICA require fine guidance with attitude accuracy less than 0.1 arcsecond. The FPC-G is a focal plane camera to achieve this high attitude accuracy and KASI is leading its development. The SPICA project is now under the Risk Mitigation Phase 2 (RMP2) and one of major risks is to satisfy the requirement of pointing and attitude control. To assess the impacts of disturbance sources on the attitude control and devise methods to mitigate possible risks, a software simulator of the FPC-G is under the development. In this presentation, we report the status of development of the simulator and the development plan during the RMP2.

• Publications of The Korean Astronomical Society
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• v.28 no.1
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• pp.1-6
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• 2013

Real-time data reduction pipeline for the Korea Microlensing Telescope Network (KMTNet) was developed by Korea Astronomy and Space Science Institute (KASI). The main goal of the data reduction pipeline is to find variable objects and to record their light variation from the large amount of observation data of about 200 GB per night per site. To achieve the goal we adopt three strategic implementations: precision pointing of telescope using the cross correlation correction for target fields, realtime data transferring using kernel-level file handling and high speed network, and segment data processing architecture using the Sun-Grid engine. We tested performance of the pipeline using simulated data which represent the similar circumstance to CTIO (Cerro Tololo Inter-American Observatory), and we have found that it takes about eight hours for whole processing of one-night data. Therefore we conclude that the pipeline works without problem in real-time if the network speed is high enough, e.g., as high as in CTIO.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1057-1064
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• 2017

High sensitivity magnetic sensor having foreign metal detection capability is proposed utilizing giant magneto-impedance effect. Strip sensor showed the increasing output voltage when the external magnetic field was applied along with strip from strip grounding point, although the initial DC voltage varied depending on the pointing direction of strip sensor. Proposed sensor was able to eliminate more than half of background noise using active noise filter to achive high sensitivity, and it showed the capability to detect magnetized foreign metal object independent of ambient electro-magnetic noise and earth magnet. In case of ferrous sphere, the metal detection up to 0.8mm diameter was experimentally demonstrated at 5mm distance from strip sensor.