• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.291-294
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• 1996

The .Japanese sun observing satellite, Yohkoh, has been operational for five years and her scientific instruments are still in good condition. They have revealed ample of evidences that solar flares were triggered by magnetic reconnection, which was, for the first time, clearly indicated to take place in the solar corona. Cusp structures in soft X-rays and a new type of hard X-ray sources at the top of flaring loops have strongly supported the scenario originally proposed by C-S-H-KP. Nonthermal energy input in hard X-rays and thermal energy estimated from soft X-rays are fundamentally consistent with the interpretation of thick-target and chromospheric-evaporation models (Neupert effect). X-ray jets, another discovery of Yohkoh, were also associated with magnetic reconnection, as a result of the interaction of emerging fluxes with pre-existing coronal loops. Temperature structures of active regions, quiet sun, and coronal holes had very dynamic differential-emission-measure (DEM) distributions and high-temperature tails of DEM were considered to come from the contribution of flare-like activity.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.35.2-35.2
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• 2018

Magnetic fields in clusters of galaxies play a critical role in shaping up the intracluster medium. Their existence has been established through observations of synchrotron emission, especially from radio relics and halos, as well as observations of rotation measure. In the so-called Sausage relic, which is one of Mpc-size giant radio relics detected in the outskirts of merging clusters, for instance, the magnetic fields are believed to have a few ${\mu}G$ strength and a Mpc scale. The observed magnetic fields are conjectured to be produced by the process of small-scale turbulence dynamo. To investigate the dynamo origin, we simulate the development of turbulence and the follow-up amplification of magnetic fields in galaxy clusters using a three-dimensional magnetohydrodynamical(MHD) code. Turbulence is induced in highly stratified backgrounds expected in clusters, and driven sporadically mimicking major mergers. We here present preliminary results, aiming to answer whether the turbulence dynamo scenario can explain observed magnetic fields in clusters of galaxies.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.60.3-61
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• 2018

Abell 115 is a renowned cluster merger at z=0.197. It exhibits an asymmetric X-ray distribution with cometary tails and a megaparsec-sized radio relic stretching in the northeastern direction from the core of the northern cluster. Many observations have concluded that this cluster merger has a large impact parameter, but there has been no numerical analysis on the structure of Abell 115. In this study, we simulate Abell 115 with Gadget2 N-body/SPH code to reproduce the X-ray and weak lensing features of Abell 115. We find a new plausible merger scenario of Abell 115, wherein the northern cluster is currently in an outgoing phase. The predicted X-ray emission has a similar morphology to the observed tail of the northern cluster. However, in order to reproduce the observed line-of-sight velocity and projected distance while maintaining the two systems gravitationally bound, the system should possess a large projection angle, which makes the shock look considerably more diffused than the observed radio relic.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.61.2-61.2
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• 2018

ZwCL 1447.2+2619 is a merging galaxy cluster at z=0.37 with clear substructures in X-ray emission and galaxy distribution. In addition, the system possesses distinct radio relics. In order to constrain the merger scenario, it is necessary to measure both the distribution and mass of the cluster dark matter. We perform weak lensing analysis of ZwCL 1447.2+2619 using Subaru imaging data. We detect clear lensing signal from the cluster after carefully addressing instrumental systematics. In this poster, we present our preliminary results on our mass reconstruction and discuss the comparison with X-ray and radio results.

• Environmental and Resource Economics Review
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• v.11 no.1
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• pp.145-184
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• 2002

This paper analyzes the impact of imposing carbon tax on the Seoul economy to reduce Greenhouse Gas(GHG) emission. We construct the social accounting matrix of Seoul, specifying energy and transport sectors which is closely related to air pollution. Then, we formulated the computable general equilibrium (CGE) model of seoul and performed scenario analysis. The main result shows that the economic cost of GHG reduction is quite large but the health benefit is also considerable. It also suggests the importance of cost effective measures such as the development of new energy technology and the improvement of energy efficiency.

• Journal of Environmental Impact Assessment
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• v.22 no.1
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• pp.109-116
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• 2013

By IPCC climate change scenario, the socioeconomic actions such as the land use change are closely associated with the climate change as an up zoning action of urban development to increase green gas emission to atmosphere. Prediction of the land use change with rational quality can provide better data for understanding of the climate change in future. This study aims to predict land use change of Cheongju in future and SLEUTH model is used to anticipate with the status quo condition, in which the pattern of land use change in future follows the chronical tendency of land use change during last 25 years. From 40 years prediction since 2000 year, the area urbanized compared with 2000 year increases up to 87.8% in 2040 year. The ratios of the area urbanized from agricultural area and natural area in 2040 are decreased to 53.1% and 15.3%, respectively.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.71.2-71.2
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• 2016

Merging galaxy clusters, such as PLCKG287.0+32.9, provide a window into the formation process of the large scale structure of the universe. PLCKG287.0+32.9 is an enormous merging galaxy cluster with mass estimated to be ~10^15 Msun. It hosts a pair of mega-parsec sized radio relics with projected offsets from the X-ray center of approximately 350kpc and 2.7Mpc, suggesting a NW-SE merging scenario with relics originating from two separate passes (Bonafede et al. 2014). A detected radio halo coincides with the center of x-ray emission. We present the motivation for our weak lensing study of the merging galaxy cluster PLCKG287.0+32.9 using recent Subaru optical imaging. We discuss the basics of weak-lensing and the criteria for source selection. In addition, we describe our method of PSF modeling and mass reconstruction.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.88.2-88.2
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• 2012

We present kinematic properties of the narrow-line region in three type-2 QSOs at z~0.35, using 2-D spectra obtained with the VIMOS integral field unit spectrograph at the Very Large Telescope. One of the objects shows a line-of-sight velocity shift of the [OIII] and $H{\beta}$ lines up to 40km/s on a 15 kpc scale, which can be interpreted as either outflow or rotation. The outflow scenario is supported by the presence of blue wings and a radio structure showing lobes in the same direction. Another object features double-peaked emission lines which can be decomposed into two velocity components. Its Hubble Space Telescope image shows two nuclei separated by ~0.2"(~1kpc), implying this may be a binary AGN.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.651-656
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• 1997

Efforts are made to examine the role nuclear energy under the international carbon emissions regulation. To do so, an econometric model for energy demand and supply is developed. Here, several scenarios on the regulation are assumed and then each scenario is analyzed by using this model. This model also makes it Possible to analyze the effect of carbon tax. The results show that share nuclear increases up to 60% in 2020 Instead 45% makes GDP rise by 1.9% while the electricity price lower by 46% in carbon emission regulation.

• Journal of Climate Change Research
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• v.9 no.1
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• pp.91-102
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• 2018

The Korean government submitted the Intended Nationally Determined Contributions (INDC) to UNFCCC which aims to reduce 37% greenhouse gas emission for the opportunity of developing new energy industry and industry innovation by 2030 compared with Business-As-Usual scenario taking into account its international responsibilities and hosting headquarters of Green Climate Fund (GCF) secretariat. The 37% reduction is composed of 25.7% in the domestic markets and 11.3% in the international carbon markets. To achieve the reduction target in the international carbon market mechanisms, it must use the linkage of international carbon markets and develop new renewable energy technology for CDM and ODA. Finally, it must improve carbon capture storage (CCS) technology and establish domestic CCS institutional systems as soon as possible. And, it must activate CCS information exchange for the international cooperation on UNFCCC movement.