• 한국산업융합학회 논문집
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• 제27권2_2호
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• pp.325-332
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• 2024

Contemporary power systems demand efficient and sustainable technologies. Single-phase induction motors, while widely used, face efficiency challenges due to inherent rotor losses. Proposed solutions include the Line-start Permanent Magnet Synchronous Motor (LSPMSM), leveraging permanent magnets for enhanced energy density but facing demagnetization and cost issues. Alternatively, the Line-start Synchronous Reluctance Motor (LSRM) operates as a hybrid motor without permanent magnets, reducing rotor losses and potentially improving efficiency. This paper focuses on designing an LSRM rotor for air conditioner compressors, analyzing start-up characteristics and efficiency through finite element analysis. A comparative study with single-phase induction motors provides insights for future motor technology selection, balancing efficiency and other requirements.

• 경영과정보연구
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• 제34권1호
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• pp.211-225
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• 2015

본 연구의 목적은 부실기업에서 회생과정을 거쳐 정상기업으로 전환된 회생기업을 대상으로 기업부실 원인과 기업이 선택하는 회생전략 사이의 관련성을 확인하고, 기업이 추구하는 회생전략에 따라 회생성과가 어떻게 달라지는지를 확인하는 데 있다. 국내 상장된 제조기업 중 2000년부터 2012년까지 법원에 법정관리 및 화의신청을 한 기업과 워크아웃 기업중 기업회생에 성공한 113개 기업을 대상으로 설문조사를 실시하였고 회수된 55개 설문과 공시자료를 바탕으로 다중회귀모형에 의해 실증 분석한 결과를 요약하면 다음과 같다. 먼저, 내부부실원인은 자산감축과 비용절감, 즉 효율성제고전략에 긍정적인 영향을 미치는 것으로 나타났고, 반대로 외부부실원인은 수익창출전략(제품/서비스감축, 제품/서비스확대)에 긍정적인 영향을 미치는 것으로 나타났다. 다음으로, 기업이 추구하는 회생전략에 따라 회생성과가 달라지는 지를 실증 분석한 결과, 효율성제고전략(자산감축과 비용절감)은 부채비율감소에 긍정적인 영향을 미치고, 반대로 수익창출전략(제품/서비스감축과 제품/서비스확대)은 매출액증가율에 긍정적인 영향을 미치는 것으로 나타났다. 본 연구는 기존의 부실원인과 회생전략, 회생전략이 회생성과에 미치는 포괄적 분석모형을 넘어 회생원인에 따라 기업이 보다 주안점을 두는 회생전략이 어떻게 달라지며, 회생전략에 따라 회생성과도 달라질 수 있음을 실증적으로 규명해 보았다는데 연구의 의의를 찾을 수 있다.

• 한국농촌건축학회논문집
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• 제20권1호
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• pp.69-76
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• 2018

This study is to research technical measures for improving energy efficiency in the conservation and reuse of historic buildings focused on the recent research trends and case studies of the west. These measures are broadly classified into three types, the passive measures for saving energy and increasing comfort, the most cost-effective energy saving strategies, and the renewable energy sources. Firstly, the passive measures are divided into the elements and systems. The passive elements are awnings and overhanging eaves, porches, shutters, storm windows and doors, and shade trees. There are also the natural ventilation systems such as the historic transoms, roofs and attics to improve airflow and cross ventilation to either distribute, or exhaust heat. Secondly, the most cost-effective energy efficiency strategies are the interior insulation, airtightness and moisture protection, and the thermal quality improvement of windows. The energy efficiency solutions of modern buildings are the capillary-active interior insulation, the airtightness and moisture protection of interior walls and openings, and the integration of the original historic window into the triple glazing. Beyond the three actions, the additional strategies are the heat recovery ventilation, and the illumination system. Thirdly, there are photovoltaic(PV) and solar thermal energy, wind energy, hydropower, biomass, and geothermal energy in the renewable energy sources. These energy systems work effectively but it is vital to consider its visual effect on the external appearance of the building.

• Asian-Australasian Journal of Animal Sciences
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• 제23권6호
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• pp.825-832
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• 2010

The United Nations Convention on Biological Diversity defines biotechnology as "Any technological application that uses biological systems, dead organisms, or derivatives thereof, to make or modify products or processes for specific use" Biotechnology has made tremendous contributions to improve production efficiency of agriculture during the last century. This article reviews successful examples of application of bio-fermentation in improving swine nutrition efficiency mainly based on the authors'z own research experience. Production of feed grade supplemental amino acids by bio-fermentation allowed nutritionists to formulate accurate feed for optimal lean growth and reduced nitrogen excretion. Recent issues with high feed grain prices caused potential feed quality problems. Bio-fermentation allowed nutritionists to use exogenous supplemental enzymes such as phytase and NSPases in swine diets, thereby improving nutrient utilization and reducing nutrient excretion to the environment. Yeast metabolites are also produced by bio-fermentation and have been repeatedly shown to improve milk production of sows during early lactation even though actual mechanisms are still to be investigated. Bio-fermentation technology also allowed nutritionists to prepare vegetable protein sources with large protein molecules and anti-nutritional factors suitable for feeding newly weaned piglets, as selected microorganisms significantly reduce specific anti-nutritional factors and size of peptides. Preparations of vegetable protein sources suitable for newly weaned pigs will greatly contribute to swine nutrition by providing efficient alternatives to the use of animal protein sources that are often expensive and somewhat against societal preference. Considering the few examples listed above, biotechnology has closely influenced improvement of production efficiency in the swine industry. As we have limited resources to produce meat to satisfy ever-increasing global demands, extensive adaptation of biotechnology to enhance production efficiency should be continued. However, at the same time, wise and careful application of bio-technology should be considered to ensure production of safe food and to meet the expectations of our society.

• KIEAE Journal
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• 제6권3호
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• pp.43-48
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• 2006

This paper aims to suggest ways of institutionally improving standards that must be applied when installing Water Reclamation/Reuse (WRR) system based on efficiency analysis. Currently, the standard for WRR system establishment requires that the system should treat more than 10% of used water in the building of over $60,000m^2$ in total area of all floors, but our research has found that it would be more effective to change the standard to $150-m^3-per-day$ reclaimed water or the total area of all floors of $30,000m^2$ ($50,000m^2$ in the case of an office building). In other words, what this paper suggests is not a one-size-fits-all standard based on the total area of all floors, but a reasonable and flexible standard that takes into account efficiency and a unit water usage according to a building's purpose. Furthermore, this paper recommends a new WRR standard that can be applied to large-scale land development for housinglots, like the New Town. The recommendation is based on the economic analysis that the WRR system will ensure efficiency only if the amount of reclaimed water is over 4,000 tons per day, which corresponds to 4 millions square meters of housinglots. Regarding the size of the established facility, this paper suggests changing the standard, which is now set at over 10% of water usage, to what is relative to the total amount of use of reclaimed water in order to ensure efficiency and promote use of reclaimed water. In addition, this paper proposes that governmental support should be offered not only to facility owners, who are recipients at present, but also to facility builders. By doing so, those who donate a facility to the government, central or local, after building it, can be provided with substantial aid. Therefore, the application of the institutional improvement suggested in this paper is expected to create environment-friendly living conditions and boost the quality of life by encouraging people to secure water resources efficiently in buildings, and in a wider range, in cities.

• 조명전기설비학회논문지
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• 제26권12호
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• pp.9-20
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• 2012

This paper proposes the efficiency optimization control of interior permanent magnet synchronous motor(IPMSM) drive using series connected-fuzzy neural network PI(SC-FNPI) controller. The PI controller is generally used to control IPMSM drive in industrial field. However, the PI controller has problem which is falling control performance about parameter variation such as command speed, load torque and inertia due to fixed gain of PI controller. Therefore, to improve performance of PI controller, this paper proposes SC-FNPI controller adjusted input of PI controller by FNN controller according to operating conditions. Also, this paper proposes efficiency optimization control which is improving efficiency with minimize loss. The SC-FNPI controller proposed in this paper is compared control performance with conventional FNN and PI controller about command speed, load torque and inertia variation. And the efficiency optimization control is compared with $i_d=0$ control about loss and efficiency. The SC-FNPI controller proposed in this paper shows more excellent control performance for rising time, overshoot and steady-state error. Also efficiency optimization control is increased efficiency by reducing loss.

• 펄프종이기술
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• 제46권5호
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• pp.61-68
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• 2014

The energy efficiency of papermaking process becomes more significant because of various new regulation of the energy consumption and the green house gas emission. In this study, the effects of wood powder addition on the drainage and the drying efficiency of the OCC based paper products, linerboard, were deeply investigated for improving energy efficiency. The fractionation of wood powder depending on the size were conducted. The bigger size of wood powder resulted in the higher bulk and the higher drainage efficiency, but the lower paper strength. The drying efficiency were in detail evaluated depending on the drying process level. In the first section of drying process until the 80% solid level, there were no significant changes in the drying efficiency by the addition of wood powder. However, after the 80 % solid level, the drying efficiency was greatly improved by the addition of wood powder. Those results showed the addition of wood powder could greatly affect not only the drainage in forming and wet pressing but also the drying process.

• 융합경영연구
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• 제9권3호
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• pp.11-21
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• 2021

Purpose: The purpose of this study is to understand the status quo of production efficiency in private industrial enterprises above designated scale in China's 31 provinces (including municipalities directly under the central government, autonomous regions) (hereinafter referred to as China's 31 provinces). Research design, data and methodology: Find out the factors affecting the development of production efficiency in private industrial enterprises, using DEA, Data Envelopment Analysis and Malmquist index analysis, build the evaluation model of production efficiency in private industrial enterprises, and analyze the data of China's 31 provinces private industrial enterprises in 2015-2019. Results: The research results show that the production efficiency of private industrial enterprises in China is improving on the whole. Although the total factor productivity has decreased slightly, the overall efficiency and pure technical efficiency have increased significantly. Conclusions: The conclusion of this study can provide reference for Chinese private industrial enterprises to improve production efficiency and make development plan. The limitation of this paper lies in the fact that the private industrial enterprises in inefficient provinces have not been given specific improvement plans.

• 동아시아경상학회지
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• 제9권1호
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• pp.41-51
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• 2021

Purpose - The purpose of this study is to propose strategies of improving efficiency of 20 listed port companies in China based on analysis of their input-output indexes from 2014 to 2018. Research design, data, and methodology - In this paper, the relevant input-output indicators of 20 listed port companies in China from 2014 to 2018 were adopted. Data derived from the company annual reports announced by Shanghai stock exchange and Shenzhen stock exchange. Comprehensive efficiency and pure technical efficiency were measured from output perspective by DEA and Malmquist index, and efficiency changes and regional efficiency were analyzed. Result - The results showed that the efficiency value of 20 listed port companies in China fluctuated and increased during 2014-2018, regional efficiency was unbalanced, and change of MPI was influenced by internal factors and external factors. Listed port companies affected by internal and external factors needed to make appropriate response to internal and external factors. Conclusion - The research conclusion can provide important reference information about management and planning for port companies in China and related areas. However, this paper is limited to the availability of data. So the improvement scheme for listed companies in inefficient regional ports needs further study, such as using AHP method.

• 전자공학회논문지B
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• 제33B권6호
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• pp.92-101
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• 1996

This paper presents a new mehtod with which we can improve the efficiency (both of speed and precision) of FPN$^{[1]}$. Our method makes use of the basic propositions smong the conditional propositions of a goal proposition. The basic propositions are represented as ource vertices on an FPN. Therefore, we introduce an efficient algebraic algorithm which finds source vertices of FPN.