• International Area Studies Review
• /
• v.15 no.3
• /
• pp.55-76
• /
• 2011

In this paper, we estimate a model that incorporates key features of business cycles, co-movement among economic variables and switching between regimes of expansion and recession, to aggregate quarterly data for the NAFTA region. Two common factors reflecting the permanent and transitory components of the business cycle in the region, along with the turning points from one regime to the other, were extracted from the data by using the Kalman filter and maximum likelihood estimation approach of Kim (1994). Estimation results confirm that a typical aspect of business cycles are also observed (i.e., recessions are steeper and shorter than recoveries) in the region, and that both co-movement and that regime switching are found to be important features of the business cycle. The two common factors produce sensible representations of the trend and cycle, and the estimated turning points are in line with independently determined chronologies. It also turns out that the degree of synchronization between the NAFTA region and Korea, has significantly increased since the entry into force of the NAFTA.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.10a
• /
• pp.121-122
• /
• 2004

• Proceedings of the Korean Nuclear Society Conference
• /
• 2005.10a
• /
• pp.47-48
• /
• 2005

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.55-58
• /
• 2007

To check the feasibility of SMART (Steam Methane Advanced Reforming Technology)system, an experimental investigation was conducted. A fluidized bed reactor of diameter 0.052 m was operated cyclically up to the $10^{th}$ cycle, alternating between reforming and regeneration conditions. FCR-4 catalyst was used as the reforming catalyst and calcined limestone (domestic, from Danyang) was used as the $CO_2$ absorbent. Hydrogen concentration of 98.2% on a dry basis was reached at $650^{\circ}C$ for the first cycle. This value is much higher than $H_2$ concentration of 73.6% in the reformer of conventional SMR (steam methane reforming) system. However, the hydrogen concentration decreased because the $CO_2$ capture capacity decreased as the number of cycles increased.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.3
• /
• pp.159-165
• /
• 2008

This paper deals with the optimum high pressure control algorithm for a transcritical $CO_2$ mobile air-conditioning system with belt-driven compressor to achieve the maximum COP. The experiments were performed to find out the maximum COP conditions with various operating conditions. The experimental results showed that the COP was increased and then decreased with increase of the refrigerant high pressure for the system. Therefore the value of high pressure which has maximum COP could be selected. Furthermore, the strong (linear) relation between the optimum high pressure and the gas cooler outlet temperature was revealed, which suggests the use of a simple controller with only one parameter for the transcritical $CO_2$ cycle.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.103.3-104
• /
• 2003

Activation of hepatic stellate cell has been identified as a critical step in hepatic fibrogenesis and is regulated by several factors including cytokines and oxidative stress. In this study, we assayed effects of saponin (CKS), inulin (CKI) and oligo-sugars (CKO) isolated from Platycodon grandiflorum A. DC, changkil (CK) on experimental cell cycle arrest and apoptosis in hepatic stellate cell line (HSC-T6). CKS induced cell arrest at G$_1$. CKS also reduced intercellular reactive oxygen species and collagen synthesis in hydrogen peroxide-induced oxidative stress and acetaldehyde-stimulated collagen synthesis, respectively, in HSC-T6 cells. (omitted)

• New & Renewable Energy
• /
• v.6 no.4
• /
• pp.15-29
• /
• 2010

In order to make the best choice for $CO_2$ abatement using renewable energy technologies, it is important to be able to adapt these technologies on the basis of their sustainability, which may include a variety of environmental indicators. This study examined the comparative sustainability of renewable technologies in terms of their life cycle $CO_2$ emissions and embodied energy, using life cycle analysis. The models developed were based on case studies of bioenergy pilot plant in P city of Kyungki province. Final results were total emission of $CO_2$ in Pocheonsi is 670,041 $tCO_2$, around 500,877 $tCO_2$ for electricity and for heat generation, and 169,164 $tCO_2$ for transportation. When used $1,984\;m^3$/day of waste (pig manure etc.) and operated CHP with wood chips of 144,664 ton/year, the $CO_2$ emission in P city was left as is an emission of 449,274 $tCO_2$ and an abatement of $CO_2$ in this region was increased by 32.9%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.8
• /
• pp.545-552
• /
• 2010

Research and development efforts to reduce $CO_2$ emission are in progress to cope with global warming. $CO_2$ emission from fossil fuel fired power plants is a major greenhouse gas source and the post-combustion $CO_2$ capture is considered as a short or medium term option to reduce $CO_2$ emissions. In this study, the application of the post-combustion $CO_2$ capture system, which is based on chemical absorption and stripping processes, to typical fossil fuel fired power plants was investigated. A coal fired plant and a natural gas fired combined cycle plant were selected. Performance of the MEA-based $CO_2$ capture system combined with power plants was analyzed and overall plant performance including the energy consumption of the $CO_2$ capture process was investigated.

• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.153-153
• /
• 2010

The world is moving towards a post-carbon society and needs clean and renewable energy for sustainable development. There are many methodological approaches which are helping this shift based on analyzed data about energy resources and which focus on limited types of energy including liquid fossil, solid fossil, gaseous fossil, and biomass (e.g. IPCC Guidelines, ISO 14064-1, WRI Protocol, etc.). We should also consider environmental impact (e.g. greenhouse gas emissions, water use, etc.) and the economic cost of the renewable energy to make a better decision. Recently, researchers have addressed the environmental impact of new technologies which include photovoltaics, wind turbines, hydroelectric power, and biofuel. In this work, we analyze the environmental impact with a carbon emission factor to present a correlation between $CO_2$ emission and the cost of energy resources standardized by the energy output. In addition, we reviewed Life Cycle Assessment (LCA) as another methodology. Researchers who are studying energy systems have ignored the impacts of entire energy systems, e.g. the extraction and processing of fossil fuels. In power sector, the assessment should include extraction, processing, and transportation of fuels, building of power plants, production of electricity, and waste disposal. Therefore LCA could be more suitable tool for energy cost and environmental impact estimation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.22 no.4
• /
• pp.234-240
• /
• 2010

In October 2009, the Ministry of Land Transport and Maritime Affairs noticed 'Environment-friendly housing construction standards and performance' to build energy saving environment-friendly housings (Green Homes) for the reduction of energy consumption and carbon dioxide emission. In this study, the $CO_2$ emissions were evaluated during the life cycle of the existing apartments which were built in 1980's and Green Home apartment. $LCCO_2$ was evaluated by dividing the life cycle into three stages which are construction, maintenance and destruction stage. $CO_2$ emission from the materials for improving insulation performance was estimated by Input-output analysis. As a result, in 40 year-life cycle of $84\;m^2$ apartment, 400.68 T-$CO_2$ was emitted from 1980's apartment, on the other hand 231.02 T-$CO_2$ was emitted from Green Home apartment.