• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.847-858
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• 2015

Control strategy and corresponding parameters have significant impacts on the overall technical and economic characteristics of composite energy storage systems (CESS). A better control strategy and optimized control parameters can be used to improve the economic and technical characteristics of CESS, and determine the maximum power and stored energy capacity of CESS. A novel coordinated control strategy is proposed considering the coordination of various energy storage systems in CESS. To describe the degree of coordination, a new index, i.e. state of charge coordinated response margin of supercapacitor energy storage system, is presented. Based on the proposed control strategy and index, an optimization model was formulated to minimize the total equivalent cost in a given period for two purposes. The one is to obtain optimal control parameters of an existing CESS, and the other is to obtain the integrated optimal results of control parameters, maximum power and stored energy capacity for CESS in a given period. Case studies indicate that the developed index, control strategy and optimization model can be extensively applied to optimize the economic and technical characteristics of CESS. In addition, impacts of control parameters are discussed in detail.

• KIEE International Transactions on Power Engineering
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• 제3A권1호
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• pp.1-6
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• 2003

As power systems grow more complex and power demands increase, the fault current tends to gradually increase. In the near future, the fault current will exceed a circuit breaker rating for some substations, which is an especially important issue in the Seoul metropolitan area because of its highly meshed configuration. Currently, the Korean power system is regulated by changing the 154 ㎸ system configuration from a loop connection to a radial system, by splitting the bus where load balance can be achieved, and by upgrading the circuit breaker rating. A development project applying 154 ㎸ Superconducting Fault Current Limiter(SFCL) to 154 ㎸ transmission systems is proceeding with implementation slated for after 2010. In this paper, the resistive and inductive SFCLs are applied to re-duce the fault current in Korean power system and their technical and economic impacts are evaluated. The results show that the application of SFCL can eliminate the need to upgrade the circuit breaker rat-ing and the economic potential of SFCL is evaluated positively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.67-68
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• 2007

This Paper calculated Retail costs as the economic and environmental impacts of supplying incremental electric load growth with varying mixes of DE(Decentralized Energy) and CG(Centralized Generation) applying to WADE Economic Model in 2020.

• KIEE International Transactions on Power Engineering
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• 제4A권4호
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• pp.221-226
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• 2004

As power systems grow more complex and power demands increase, the fault current tends to gradually increase. In the near future, the fault current will exceed a circuit breaker rating for some substations, which is an especially important issue in the Seoul metropolitan area because of its highly meshed configuration. Currently, the Korean power system is regulated by changing the 154kV system configuration from a loop connection to a radial system, by splitting the bus where load balance can be achieved, and by upgrading the circuit breaker rating. A development project applying a 154kV Superconducting Fault Current Limiter (SFCL) to 154kV transmission systems is proceeding with implementation slated for after 2010. In this paper, SFCL is applied to reduce the fault current in power systems according to two different application schemes and their technical and economic impacts are evaluated. The results indicate that both application schemes can regulate the fault current under the rating of circuit breaker, however, applying SFCL to the bus-tie location is much more appropriate from an economic view point.

• Environmental Engineering Research
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• 제24권4호
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• pp.618-629
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• 2019

Along with growing population and economic development, increasing waste generation rates in developing countries have become a major issue related to the negative impacts of waste management on the environment. Currently, the business-as-usual waste management practices in Myanmar are largely affecting the environment and public health. Therefore, this study developed an alternative approach to waste management for reducing the environmental impacts in Myanmar by highlighting the greenhouse gas (GHG) emissions from business-as-usual practices and three proposed scenarios during 2018-2025. The calculation methods of the Intergovernmental Panel on Climate Change and Institute for Global Environmental Strategies were used for estimating the GHG emissions from waste management. It was estimated that the current waste management sector generated approximately 2,000 gigagrams of CO₂-eq per year in 2018, trending around 3,350 Gg of CO₂-eq per year in 2025. It was also observed that out of the proposed scenarios, Scenario-2 significantly minimized the environmental impacts, with the lowest GHG emissions and highest waste resource recovery. Moreover, the GHG emissions from business-as-usual practices could be reduced by 50% by this scenario during 2018-2025. The target of the similar scenario could be achieved if the local government could efficiently implement waste management in the future.

• 농업과학연구
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• 제38권1호
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• pp.183-190
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• 2011

The paper is to analyze multi-attributes for expanding new renewable energy in agricultural sectors which have environmental, technical, economic, and social factors consisting of 15 attributes which have both positive and negative impacts. We applied the analytic hierarchy process (AHP) to data from opinion polls. As a result of the AHP survey, the overall results indicate that the respondents more weight on economical factor than environmental, technical, and social factors for expanding new renewable energy. At the lowest level, a comparison of individual 15 attributes within three factors shows that fixed cost highest in multi-attributes, followed by operating cost, technical superiority. To achieve the public acceptance about expanding new renewable energy in agricultural sectors, the policy-makers should take all relevant factors into account through the decision-making process by the public opinions.

• 공학교육연구
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• 제5권1호
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• pp.68-76
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• 2002

It is proposed to raise the debate on Engineering and Technical Education at the global economic level and to examine some of the issues facing developing and poorer countries in managing and improving the quality of engineering education in their countries, especially in the context of internet and IT culture After the fall of the Berlin Wall, the world is now divided in two realigned blocks: one of developed(rich or advanced) countries which have a social security safety net for their population and another of developing(or poor) countries which have no such luxuries for their population. For the general public in the developing countries, any engineering or technical degree/diploma is a passport to lifelong wellbeing of an individual and his/her extended family. Therefore, the demand for such qualifications is very high and it is almost a rat race amongst school leavers to get into engineering/technical colleges. In view of this booming demand, there are hundreds of privately funded engineering/technical colleges in countries like Philippines, India, Thailand, etc., besides state funded ones. It is extremely difficult to ensure good quality in this mushrooming scenario. There are also many very small poorly resourced developing countries where there is only one engineering school and/or two-three technical colleges. Products of these schools/colleges work only in their own country and education globalization have little or no meaning for them. Besides highlighting the aforementioned general issues, the Paper also presents a few case studies on problems of accreditation and quality assessment in larger developing countries like India and the Philippines. The Paper also discusses the effects of commercialization on the quality of education and social impacts of IT revolution on educational processes.

• Wind and Structures
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• 제32권4호
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• pp.321-340
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• 2021

In 2019, 5.6% of the total energy produced worldwide came from wind. Offshore wind generation is still a small portion of the total wind generation, yet its growth is exponential. Higher availability of sites, larger producibility and potentially lower environmental impacts make offshore wind generation attractive. On the other hand, as the water depth increases, fixed foundations are no more viable, and the new frontier is that of floating foundations. This paper brings an overview of why and how offshore wind energy should move deep water; it contains material from the Keynote Lecture given by the first author at the ACEM20/Structures20 Conference, held in Seoul in August 2020. The paper is organized into four sections: the first giving general concepts about wind generation especially offshore, the second and the third considering economic and technical aspects, respectively, of offshore deep-water wind generation, in the fourth, some challenges of floating offshore wind generation are presented and some conclusions are drawn.

• 경영과학
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• 제23권2호
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• pp.59-74
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• 2006

In this paper, we investigated economic viability of UCA (Ubiquitous Contents Access) technologies from user adoption perspective. UCA technologies are expected to 9et embedded into media and telecom merging services. Embracing new technologies such as UCA technologies, forged through an industry convergence, means opting for a technological innovation that will have technological as well as economic and strategic implications. As such, we adopted user perspective innovation adoption theories to explore key antecedents affecting consumer acceptance of these emerging technologies. Subsequently. using QFD (Quality Function Deployment) method, the impacts of UCA technical functions on user's perceived value enhancements are estimated. The QFD analysis result indicates that the new UCA service technologies could achieve about 42% enhancement on user perceived adoption intention compared to existing digital contents service technologies. The proposed analysis framework and findings suggests significant insights for further research.

• 한국항만경제학회지
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• 제26권4호
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• pp.219-246
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• 2010

각 국은 국제무역 및 물류에 있어서 항만의 역할과 가치의 중요성에 주목하면서 자국 항만의 경쟁력을 강화시키기 위한 정책과 전략을 추진하고 있다. 본 연구의 목적은 전 세계 컨테이너물동량의 대부분을 차지하고 있는 3개 지역, 즉 동아시아, 유럽, 북미지역의 주요 컨테이너항만의 효율성을 비교하고 효율성에 영향을 미치는 요소들을 분석하여 제시하는데 있다. 효율성을 비교분석하기 위해 45개 항만을 대상으로 5개의 투입요소와 2개의 산출요소를 가지고 DEA 모형을 이용하였다. 또한 처리물량, 총 효율성, 기술적 효율성, 규모의 효율성 각각에 영향을 미치는 요소를 분석하기 위해 회귀분석을 실시하였다. 분석결과 동아시아 항만이 유럽과 북미의 항만보다 규모가 작음에도 불구하고 더 많은 성과를 내고 있으며 기술적으로나 규모면에서 상대적으로 더 효율적으로 나타났다. 본 연구의 분석이 지역별 항만의 특징과 효율성을 이해하는데 도움이 되고, 각 지역의 항만의 이용과 발전방향의 설정에 참조가 되기를 기대한다.