• Journal of Agricultural Extension & Community Development
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• v.1 no.2
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• pp.95-103
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• 1994

Recently Korean government has proceeded to reorganize agricultural extension system as a part of reduction plan of national governmental body. Function and characteristics of agricultural extension system under the localization was presented in the view of long term agricultural development policy.

• Journal of Energy Engineering
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• v.20 no.1
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• pp.54-62
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• 2011

Since the release of mid-term domestic GHG goals until 2020, in 2009, some various GHG reduction policies have been proposed. In case of the transportation sector for the mid-term domestic GHG goals, it targets to reduce about 30% regarding the doemstic economic growth until 2020. A major reduction method in passenger cars considers an electric car. In this study we analyze some various scenarios to compare between internal combustion engine car and electric car using break-even analysis. Through the analysis we suggest a subsidy policy for electric car.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.455-460
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• 2014

South Korea's power consumption is increasing every year. For stable electric power supply, more generation facilities are needed. But it is not easy to build nuclear power generation facilities, so provision of renewable energy is thought of as the solution. For the system's stable management, practical use of energy storing system is needed. Currently, pumping up electric power station is considered most useful. In this study, we have calculated the least amount of energy storing device by considering the renewable energy, HVDC, and change in power for the appliance of ESS in Jeju system, according to The 6th Basic Plan for Long-term Electricity Supply and Demand. Also we have calculated the amount of the battery and about the load equalizing effect to use battery as power storing device. Finally, we have calculated the reduction of electricity generation and the reduction of $CO_2$ emission with this study.

• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.149-155
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• 2014

The surface solar radiation is an important indicators for climate and agricultural research over the Earth system. For the climate and agricultural research, long-term meteorological data and accurate measured data are needed. The daily solar radiation from Jan. 2001 to Dec. 2010 have been employed in this study analyze atmospheric transmissivity for Chupungryeong. The corresponding daily value of atmospheric transmissivity is calculated for Chupungryeong meteorological data. In this paper, relationship analysis of daily solar radiation and atmospheric transmissivity is presented. It shows that atmospheric transmissivity over late December peaked in the 2000s, substantially decreased from the early-January, and changed little after that in summer. Reduction of solar radiation caused a reduction of more than 0.3 in atmospheric transmissivity during July to August. It was concluded that the atmospheric transmissivity could be very useful for evaluating solar radiation. Atmospheric transmissivity approach is suitable for daily-term simulation studies and useful for computing solar radiation.

• Smart Structures and Systems
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• v.6 no.3
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• pp.263-275
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• 2010

In the last decade, wireless sensor networks have emerged as a promising technology that could accelerate progress in the field of structural monitoring. The main advantages of wireless sensor networks compared to conventional monitoring technologies are fast deployment, small interference with the surroundings, self-organization, flexibility and scalability. These features could enable mass application of monitoring systems, even on smaller structures. However, since wireless sensor network nodes are battery powered and data communication is the most energy consuming task, transferring all the acquired raw data through the network would dramatically limit system lifetime. Hence, data reduction has to be achieved at the node level in order to meet the system lifetime requirements of real life applications. The objective of this paper is to discuss some general aspects of data processing and management in monitoring systems based on wireless sensor networks, to present a prototype monitoring system for civil engineering structures, and to illustrate long-term field test results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.113-117
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• 2009

Fly ash (called FA hereafter) that results from thermal power plants is a long-term strength improving substance with reactivity to pozzolan and has been used for long. However, large amount of FA shows many advantages such as reduction of hydratio energy, long-term improvement in strength and economic feasibility and also has difficulties from reduction in initial strength and durability. In a preceding study, fine particle cement was applied to test the effects on initial strength. Therefore in this study, the effects of fine particle cement on the quality of FA concrete were reviewed. The results can be summarized as follows. Liquidity was increased by the most at FC substitution ratio of 15%. Air capacity was reduced according to increasing substitution ratio of FA and FC. Compressive strength showed high strength expression at all ages when FC was substituted at 45%. Synthesizing the above results, appropriate mixing of FC in FA concrete can improve liquidity, reduce unit quantity and show improvement in strength. In particular, mixed use of FC seems effective in improving early quality of concrete.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.3
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• pp.237-248
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• 2017

The estimation method of economical leakage management target utilized upon planning business for improvement of revenue water ratio in South Korea is presented and applicability of methods developed in this study is assessed through application on site. With a consideration of revenue water ratio in application target area, estimation method of long-term economical leakage management target is applied. Three leakage reduction methods such as replacement of residual aged pipe, leakage investigation and restoration and water pressure management are applied with a consideration of characteristics of site. Due to difficulty of obtaining data, analysis of cost/benefit by leakage reduction methods is performed by applying method of leakages estimation equation among statistical methods. As a result of application, revenue water ratio corresponding to long-term economical leakage management target is 91.6 %.

• Journal of Powder Materials
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• v.23 no.6
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• pp.420-425
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• 2016

N-doped carbon nanofibers as catalysts for oxygen-reduction reactions are synthesized using electrospinning and carbonization. Their morphologies, structures, chemical bonding states, and electrochemical performance are characterized. The optimized N-doped carbon nanofibers exhibit graphitization of carbon nanofibers and an increased nitrogen doping as well as a uniform network structure. In particular, the optimized N-doped carbon nanofibers show outstanding catalytic activity for oxygen-reduction reactions, such as a half-wave potential ($E_{1/2}$) of 0.43 V, kinetic limiting current density of $6.2mAcm^{-2}$, electron reduction pathways (n = 3.1), and excellent long-term stability after 2000 cycles, resulting in a lower $E_{1/2}$ potential degradation of 13 mV. The improvement in the electrochemical performance results from the synergistic effect of the graphitization of carbon nanofibers and the increased amount of nitrogen doping.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.39-53
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• 1999

This thesis is to analyze and assess a new refuse collection system that was based on the term of discharge based quantity and collection of refuse from the beginning on January 1, 1995.In the case study for the refuse collection policy of metropolitan Taegu city based on the year of operation, ie, before 1994, after 1995 and as of 1998, the refuse collection policy analyzed from current position and actual condition. The results of analysis as follows. In case of discharged refuse quantity was show 20.4% reduction than the operation was begun and more 5.8% reduction as of 1998.Under the operation of the refuse collection system, therefore, management of refuse and garbage, the reduction of discharged refuse, activation of refuse collection, Recycling and expansion of financial self-reliance increased efficiency of refuse collection system. In the conclusion, more perfect refuse collection system should be developed of implemented in the near future.

• Advances in pediatric surgery
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• v.9 no.1
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• pp.24-29
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• 2003

To evaluate the clinical findings of the recurrent intussusception, 351 patients with 445 intussusceptions were reviewed. Recurrence rate, pattern of recurrence, reducibility, pathologic lead points (PLP), and operative findings and long term follow up of the multiple recurrences were analyzed. Of 351 patients, 303 had no recurrence, 26 had one recurrence, and 22 had multiple recurrences. Over all recurrence rate was 16.4% ; 18.5% were managed by air reduction, 16.2% by barium reduction and 5.9% by operation. Eleven PLPs were proved operatively and an additional 6 suspected PLPs were depicted radiologically. The most frequent PLP was ileal lymphoid hyperplasia. Intervals between reduction and recurrence were less than 2 weeks in 31 cases, between 2 weeks and 1 year in 55, and more than 1 year in 8. The longest interval was 2 years and 4 months.