• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.63.3-63.3
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• 2016

We present the two-dimensional distribution of stellar populations in five E+A galaxies from GMOS-N/IFU spectroscopy (GN-2015B-Q-15). Numerical simulations demonstrated that E+A galaxies formed by major mergers contain young stellar populations (e.g. A-type stars) that are centrally-concentrated within scales of 1 kpc. However, several IFU studies reported that A-type stars are widely distributed on ${\gg}$ 1kpc scales. In contrast, Pracy et al. (2013) found a central concentration of A-stars and strong negative Balmer absorption line gradients within 1 kpc scales for local (z < 0.03) E+A galaxies. They claimed that previous studies failed to detect the central concentration because the E+A galaxy samples in previous studies are too far (z ~ 0.1) to resolve the central kpc scales. To verify Pracy et al.'s argument and the expectation from simulations, we selected five E+A galaxies at 0.03 < z < 0.05. Furthermore, we selected the targets in the mid-infrared green valley (Lee et al. 2015). Thanks to good seeing (${\sim}0.4^{{\prime}{\prime}}{\simeq}0.33kpc$) of our observation, we are able to resolve the central 1 kpc region of our targets. We found that all five galaxies have negative Balmer line gradients, but that three galaxies have flatter gradients than those reported in Pracy et al. We discuss the results in relation with galaxy merger history.

• The Korean Journal of Applied Statistics
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• v.21 no.3
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• pp.361-375
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• 2008

We propose proper methods to impute the item nonresponse in 4-8-4 rotation sample survey. We consider nonignorable nonresponse mechanism that can happen when survey deals with sensitive question (e.g. income, labor force). We utilize modeling imputation method based on Bayesian approach to avoid a boundary solution problem. We also estimate a interview time bias using imputed data and calculate cell expectation and marginal probability on fixed time after removing estimated bias. We compare the mean squared errors and bias between maximum likelihood method and Bayesian methods using simulation studies.

• Applied Science and Convergence Technology
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• v.23 no.6
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• pp.309-316
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• 2014

A large particle accelerator requires an ultrahigh vacuum (UHV) system of average pressure under $1{\times}10^{-7}$ Pa for mitigating the impact of beam scattering from the residual gas molecules. The surface inside the beam ducts should be controlled with an extremely low thermal outgassing rate under $1{\times}10^{-9}Pa{\cdot}m^3/(s{\cdot}m^2)$ for the sake of the insufficient pumping speed. To fulfil the requirements, the aluminum alloys were adopted as the materials of the beam ducts for large accelerator that thanks to the good features of higher thermal conductivity, non-radioactivity, non-magnetism, precise machining capability, et al. To put the aluminum into the large accelerator vacuum systems, several key technologies have been developed will be introduced. The concepts contain the precise computer numerical control (CNC) machining process for the large aluminum ducts and parts in pure alcohol and in an oil-free environment, surface cleaning with ozonized water, stringent welding process control manually or automatically to form a large sector of aluminum ducts, ex-situ baking process to reach UHV and sealed for transportation and installation, UHV pumping with the sputtering ion pumps and the non-evaporable getters (NEG), et al. The developed UHV technologies have been applied to the 3 GeV Taiwan Photon Source (TPS) and revealed good results as the expectation. The problems of leakage encountered during the assembling were most associated with the vacuum baking which result in the consequent trouble shootings and more times of baking. Then the installation of the well-sealed UHV systems is recommended.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.4
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• pp.39-50
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• 2002

Field experiment was performed to investigate water and nutrient mass balances in paddy field with groundwater irrigation from May to October, 2001. The total water inflow was about 1,183mm in which rainfall, overflow from upstream paddy, and groundwater irrigation accounted for 43, 30, and 27%, respectively. Notice that the precipitation of the study period was less than the average annual precipitation. The total drainage was almost balanced with the inflow and more than half of it was occurred by surface drainage. From the nutrient mass balance analysis, the T-P output (17.56kg/ha) was estimated slightly lower than the input (20.90kg/ha) and the T-N output (130.41kg/ha) was slightly greater than the input(129.24kg/ha). However, the difference was within the expectation and the nutrient mass was thought to be balanced considering uncertainties in field experiment and other activities not included in the study such as algae and soil microorganisms. The surface discharge of nutrient, which was about 10% of total nutrient output, was mainly affected by fertilization and rainfall runoff. Therefore, prudent surface drainage plan might be necessary particularly for the fertilization period to prevent degradation of receiving water quality. The study was performed under abnormally low rainfall compared to the average annual rainfall record, and further monitoring in diverse rainfalls and irrigation methods is recommended to estimate nutrient behavior in the paddy field more reasonably.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.223-233
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• 2013

This paper studied the effects of service quality and system quality that affect customer's satisfaction and continued usage intention regarding mobile network conditions. The hypotheses and research models were completed using research factors of service quality(reactivity, empathy) and system quality(connectivity, ease of use, channel-mobility) borrowed from previous studies on DMB and IPTV. The hypotheses and research models were verified through experiments and surveys. The key finding showed that customer's expectation on service quality and system quality under fast network(Wifi) was higher than that of under slow network(3G). Furthermore, it showed that users react more sensitive to service quality than to system quality such as network speed. Based on the results, this study has the implication for expanding the understanding of the factors used in previous DMB and IPTV studies by applying them in N-screen domain.

• Journal of the Korean Ceramic Society
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• v.51 no.6
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• pp.544-548
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• 2014

Aluminum nitride was synthesized using a carbothermal method from mesoporous alumina having a high surface area (> $1,000m^2/g$) as an aluminum source and CNTs (carbon nano tubes) as a carbon source. In this case the mesoporous alumina was used as the starting material instead of ${\alpha}-Al_2O_3$ with the expectation that the mesopores in mesoporous alumina act as channels for N2 gas and elimination of CO generated as by-product. It is also expected that the synthetic temperature should be lower compared to the use of ${\alpha}-Al_2O_3$ as a starting material due to its high surface area. The crystallinity of the produced aluminum nitride was studied by XRD and FT-IR, and the microstructure was investigated by FE-SEM. Also the purity of the aluminum nitride was analyzed through N/O determinator and ICP analysis.

• Journal of Radiation Industry
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• v.5 no.4
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• pp.325-330
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• 2011

To predict the details of flow in industrial process unit, single photon emission computed tomography (SPECT) is a promising technique. Recently, industrial SPECT based on medical system has developed by researchers of the Korea Atomic Energy Research Institute (KAERI) and Hanyang University. In the present study, to confirm the effect of the number of detectors on image quality, and determine the optimal number of detectors in industrial SPECT, industrial SPECT system with various geometries were evaluated by the Monte Carlo simulation. CsI(Tl) detectors ($12mm{\times}12mm{\times}20mm$) with collimators (the geometric resolution of collimator $R_g$ was 4 cm at the center of the 30 cm diameter cylindrical vessel object) were modeled in a hexagonal array, and the point sources of $^{99m}Tc$, $^{68}Ga$, and $^{137}Cs$ were simulated at the center of the cylindrical vessel object using the MCNPX code. Then, the reconstruction images of each geometry were reconstructed using the expectation maximization (EM) algorithm. In this study, the reciprocity theorem was used to improve computation time required for system matrix of the EM algorithm. The result shows that the resolution of the reconstructed image was significantly improved by increasing the number of detectors in industrial SPECT system and more than 60 detectors will be required for the resolution of the reconstructed image.

• Cross-Cultural Studies
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• v.30
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• pp.31-51
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• 2013

In this paper, I approach corporate social responsibility as a discourse metadiscursively shaping the social relationship between corporations and society. Using a discourse-centered approach to culture, I examine how early discussions (involving legal disputes) on the rights of corporations to give evolved into a public sphere discussion as to how corporations can be viewed and redefined as social actors with capabilities to perform socially meaning actions, which here is "responsibility." I discuss how corporate social responsibility currently operates as a metadiscourse of corporate personhood, ethics, and corporate citizenship. Then, using insights from Mauss, I analyze how corporate social responsibility might be comparable to a Maussian gift exchange. Corporate social responsibility actions that are performed, indeed, are gift exchanges in that they involve the ideology of the free gift and the implicit expectation of a return to the giver. In the meantime, I argue, that in the case of corporate social responsibility, it is not the act of giving gifts (e.g., grants) that can lead to social alliances but rather the talk of gift giving, a departure from the ceremonial gift exchanges observed by Mauss. That is, here, the talk of giving shapes social alliances, thus displacing this function from the act of giving itself. The PR strategies deploy talk of the gift as a metapragmatic strategy, inviting various forms of role alignment on the part of diverse, potential and actual, participants, in a framework of corporate-sponsored gift exchange in which potential recipients compete, again at the level of metapragmatic description, to become the chosen gift recipient.

• Smart Structures and Systems
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• v.29 no.3
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• pp.499-512
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• 2022

This work proposes a novel contactless vibration damping and thermal isolation tripod platform based on Superconducting Magnetic Levitation (SML). This prototype is suitable for cryogenic environments, where classical passive, semi active and active vibration isolation techniques may present tribological problems due to the low temperatures and/or cannot guarantee an enough thermal isolation. The levitating platform consists of a Superconducting Magnetic Levitation (SML) with inherent passive static stabilization. In addition, the use of Operational Modal Analysis (OMA) technique is proposed to characterize the transmissibility function from the baseplate to the platform. The OMA is based on the Stochastic Subspace Identification (SSI) by using the Expectation Maximization (EM) algorithm. This paper contributes to the use of SSI-EM for SML applications by proposing a step-by-step experimental methodology to process the measured data, which are obtained with different unknown excitations: ambient excitation and impulse excitation. Thus, the performance of SSI-EM for SML applications can be improved, providing a good estimation of the natural frequency and damping ratio without any controlled excitation, which is the main obstacle to use an experimental modal analysis in cryogenic environments. The dynamic response of the 510 g levitating platform has been characterized by means of OMA in a cryogenic, 77 K, and high vacuum, 1E-5 mbar, environment. The measured vertical and radial stiffness are 9872.4 N/m and 21329 N/m, respectively, whilst the measured vertical and radial damping values are 0.5278 Nm/s and 0.8938 Nm/s. The first natural frequency in vertical direction has been identified to be 27.39 Hz, whilst a value of 40.26 Hz was identified for the radial direction. The determined damping values for both modes are 0.46% and 0.53%, respectively.

• Information Systems Review
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• v.12 no.1
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• pp.145-164
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• 2010

Since the third generation (3G) mobile communication service has been launched by most mobile communication operators in Korea, the portion of data service in mobile communication service becomes one of the most important factors in mobile communication service market. In past mobile communication market, most mobile communication operators made their profit mostly from voice communication service. However, the portion of profit from data service has gradually increased based on both video phone call and mobile Internet service. In this situation, LG telecom launched the full browsing mobile Internet service. This service provides a new type of mobile Internet service platform which enables to access the World Wide Web using mobile browsers, so we generally access the Web using web browsers in the desktop computer. Under the open network structure of mobile Internet like situation, it is very important to analyze the factors which can affect the competition between mobile communication service companies. So, in this paper, we first present the current state of full browsing service, followed by the expectation of its growth potentials and barriers. Then, we analyze the advantages and disadvantage of LG telecom as a first-mover and SK telecom/KTF as followers. Finally, based on this analysis, we predict the future competition among these companies and the market.