• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.135-140
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• 2005

This paper summarizes the recent progress made by our group at Seoul National University on studies of the evolution and formation of distant galaxies. Various research projects are currently underway, which include: (i) the number density of distant early-type galaxies (z < 1); (ii) the optical-NIR color gradient of nearby early-type galaxies; (iii) J - K-selected Extremely Red Objects (EROs) in field (CDF-S) and the cluster environment; and (iv) the Lyman-break galaxies in the Spitzer First Look Survey (FLS) field. These works will constrain the mass evolution and the star formation history of galaxies in different environments, and the results will serve as useful contraints on galaxy formation models.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.196-201
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• 2009

Global warming issues due to the $CO_2$(Carbon Dioxide) become increasing since the Industrial Revolution. After the Kyoto protocol at 1997, nations which have the prearranged quota drives their national project for the reduction of $CO_2$. Korean Government start to the related big projects in the view of three concepts which have consist of the $CO_2$ exhaust reduction on land, $CO_2$ capture and $CO_2$ storage. Furthermore, the storage method putting into depleted region underground is accepted by the London Convention while the ocean diluted method discharging the liquid $CO_2$ into the deep ocean using the long pipe which is towed by the surface vessel is underway for the research steps which means that there are many potentials for the R&Ds that need for the breakthrough. In this paper, the role and example of the Computational Fluid Dynamics for the feasibility study of the $CO_2$ ocean sequestration is mentioned.

• BMB Reports
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• v.42 no.11
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• pp.705-712
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• 2009

Our understanding of the relationships between genes, brains, and behaviors has changed a lot since the first behavioral mutants were isolated in the fly bottles of the Benzer lab at Caltech (1), but Drosophila is still an excellent model system for studying the neurobiology of behavior. Recent advances provide an unprecedented level of control over fly neural circuits. Efforts are underway to add to existing GAL4-driver lines that permit exogenous expression of genetic tools in small populations of neurons. Combining these driver lines with a variety of inducible UAS lines permits the visualization of neuronal morphology, connectivity, and activity. These driver lines also make it possible to specifically ablate, inhibit, or activate subsets of neurons and assess their roles in the generation of behavioral responses. Here, I will briefly review the extensive arsenal now available to drosophilists for investigating the neuronal control of behavior.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.566-573
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• 2010

Nanotechnology has been applied to various fields in our life. Although there is a limitation of nanoparticle monitoring so far, it is expected that nanoparticles are widely distributed in environmental multimedia. Nanoparticle is known to be more toxic than its corresponding bulk material. For this reason, developed countries and international organizations are preparing for future regulation. To evaluate the safety of nanoparticles, nanotoxicity studies are internationally underway. In this study, we evaluated the research trends of ecotoxicity of nanoparticles in water environment. Test species include fish, water flea, and algae. Nanoecotoxicological studies are rapidly increasing and the experimental designs become more sophisticated. Physicochemical properties of nanoparticles should be measured and the ionization potential is important for metal-based nanoparticles. We analyzed the research trends based on the type of nanoparticles and test species. Also experimental aspects of nanoecotoxicology are considered.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.4
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• pp.267-273
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• 2017

In recent years, there is an increasing demand for DC microgrid because the digital load due to DC increases and the efficiency of the distribution system increases due to loss of conversion losses and conversion stages due to reactive power compared to AC distribution. Currently, with the support of the KEPRI, the development of an electronic large-capacity circuit breaker for DC distribution protection, which has been underway since 2016, is proceeding. In this paper, as a part of this project, we modeled the DC microgrid connected with PV using PSCAD. The converter station, AC/DC converter control, PV and MPPT controller are designed. In order to evaluate the performance of the modeled DC microgrid, it is examined whether the voltage is adjusted according to the load variation.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.301-305
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• 2000

The present study is part of the Special Research Project for the Construction of a Kansei Sensory Evaluation Model that is currently underway at the University of Tsukuba. In this study, a robot was operated by remote control at an actual art museum as part of a preliminary experiment. The results obtained therefrom were used to consider how people might view exhibits. In a previous study, a standard lens and s wide-angle lens were used to analyze differences in sensory-based movements, while VRML was used to analyze differences in these movements between a virtual and an actual museum. In the present study, the time delay in remote operation, which is currently unavoidable, placed some restrictions on the degree of freedom with which exhibits could be viewed, but it was apparent that sensory evaluation could be possible depending on the search behavior and viewing time. Furthermore specific viewing behaviors using the robot were observed, suggesting that new Kansei sensory perceptions were derived from these behaviors.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.1
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• pp.1-11
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• 2009

Current therapies against ulcers caused by H. pylori infection consist of antibiotics, an acid reducer, and some clinical trials underway to develop a H. pylori vaccine. We develop a structured model with age-dependent mortality of peptic ulcers and H. pylori infection. Our main goal is to analyze our structured model mathematically and to compare it to our previously unstructured model to examine the disease transmission dynamics in terms of annual prevalence and annual incidence of the disease.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.361-364
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• 2011

Nowadays, an explosive increase of mobile devices has triggered a lot of research into radio resource management. Therefore, many studies have been done and still underway to use this limited resource efficiently. However, most of the existing studies focused on efficiency in mac layer. In this paper, I proposed a timer to manage radio resource, which refreshes the timer's values based on the number of connections dynamically. This dynamic timer enables Base Station (BS) to be able to manage available radio resources efficiently and accommodate much more Mobile Stations (MSs). Simulation result showed that BS with dynamic timer could accommodate the MS about 30% more, compared with BS with a static timer in terms of radio resource management. Dynamic timer is not restricted to any specific network standard. So its mechanism is practical and implementable without changing the original standard, which can contribute to service providers by increasing capability that BS can support.

• Proceedings of the Korean Nutrition Society Conference
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• 1995.07a
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• pp.550-558
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• 1995

Nutrition surveillance can sometimes be a powerful tool for raising awareness of nutrition problems at national and community levels and for promoting improved policies and programs to improve nutrition. Whereas many countries have been collected nutrition surveillance data for several years, the experience is often discouraging in terms of converting this data into information deemed useful by decision-makers and in terms of demonstrating impacts on decision-making. This presentation will describe the results of multi-country review of this problem undertaken by UNICEF in 1992-1994, the revised concept of "Nutrition Informatin Strategies" that emerged from the review, and the efforts currently underway at communtiy level in upstate New York to implement this revised concept.d concept.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.7
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• pp.8-13
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• 2015

Recently, because a renewable power source must operate as a constant rate in accordance with RPS(Renewable Portfolio Standard), the study of the renewable power sources has been ongoing. Especially because of noise of wind turbine, troubleshooting, and urban greening business, research related with small wind turbine are underway. The economics and reliability are important parts for the activation of small wind turbine, such as solar energy. In this paper, by analyzing the temperature variations for each location and efficiency of power conversion devices in accordance with short period wind speed changes in simulation test, we reviewed the safety about temperature variations of wind generator and the method of selection of power converter.