• Journal of Electrical Engineering and Technology
• /
• v.12 no.6
• /
• pp.2127-2137
• /
• 2017

A virtual power plant (VPP) is a system that virtually integrates power resources based on the VPP participating customer (VPC) unit and operates as a power plant. When VPP operators manage resources to maximize their benefits, load reduction instructions may focus on more responsive VPCs, or those producing high profitability, by using VPC resources with high operation efficiency. VPCs may thus encounter imbalance problems during operation. This imbalance in operation time would bring more participation for some VPCs, causing potential degradation of their resources. Such an operation strategy would be not preferable for VPP operators in managing the relationship with VPCs. This issue impedes both continual VPC participation and economical and reliable VPP operation in the long term. An operation algorithm is therefore proposed that considers the operation time of VPC generators for mandatory reduction of power resource consumption. The algorithm is based on constraints of daily and annual operation times when VPP operators of local generators perform capacity-market power transactions. The algorithm maximizes the operator benefit through VPP operations. The algorithm implements a penalty parameter for imbalances in operation times spent by VPC generators in fulfilling their obligations. An evaluation was conducted on VPP operational effects by applying the algorithm to the Korean power market.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.6
• /
• pp.921-930
• /
• 2013

From an economic perspective, an enterprise's business activity depends on the efficient use of corporate resources for generating profits. However, on the enterprise side, it is difficult to measure and evaluate the effective use of each resource. This paper suggests an alternative for eliminating process inefficiencies in the consolidation of competitive power in auto parts manufacturing company A. Multitudinous process variables from company A's raw materials-to-shipment process are configured as input resources, and a Data Envelopment Analysis(DEA) is carried out to determine economical benefit of said resources' operation, as well as how products are manufactured. The DEA model offers a non-parametric approach to measuring relative efficiency using input and output factors. Furthermore, AHP is used for logically deciding the importance of each evaluation factor. In general, DEA models have been used for measuring efficiency of the service and public sectors. However, this study focused on measuring the efficiency of SMEs production lines.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.3
• /
• pp.414-422
• /
• 2006

Before applying PVA bio-beads to practical biological treatment of nitrate-containing wastewater, their characteristics were examined. PVA bio-beads could steadily produce nitrogen gas from nitrate for 28 batches with 0.04 ml/l/h of the maximum gas production rate; however, the maximum gas production rate dropped remarkably thereafter with apparent deformation of beads. Addition of 2.2% solution containing 1% casamino acid, 1% yeast extract, 0.1% mineral solution, and 0.1% vitamin solution to the culture medium resulted in not only recovery of activity of deactivated beads, but also a higher rate of gas production. Calculation of economic benefit for the use of bio-beads in a long-run operation indicated that reactivation of bio-beads by chemicals had economical advantages over packing new bio-beads in the system. The continuously stirred bioreactor exhibited a satisfactory performance at HRT of 20.0 h. With a 9.5 mg $NO_{3}^{-}N/l/h$ nitrate removal rate, nitrate could completely be removed without nitrite accumulation. The use of PVA bio-beads in nitrate removal appears very promising.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.52 no.4
• /
• pp.27-34
• /
• 2010

본 연구는 농촌마을을 환경친화적으로 계획하는데 활용할 수 있는 신재생에너지 중에서 태양에너지를 고려한 농촌그린빌리지 디자인에 대한 경제성분석을 목적으로 한다. 이 논문에서는 경제적 측면에서 에너지 수지를 고려하여 세 가지 형태의 연구대상 농촌마을에 대한 분석을 실시하였다. 연구대상 농촌마을들에서 실제로 사용했던 전체 에너지를 태양광 발전으로 대체하기 위한 태양광 발전시스템인 3 kWp의 단위 모듈 (PV 시스템)의 개수들을 마을별로 추정하였다. 경제성 분석에서는 두 개 마을의 순현재가치 (NPV)가 평가기간 25년내에 마이너스 값을 보였으며, 나머지 하나의 마을에서 경제성이 있는 것으로 분석되었다. 정부에서 시설설치 보조금을 60 % 지원해 줄 경우에는 모든 마을에서 25년 내에 경제성이 있는 것으로 평가되었다. 경제성 평가 관련인자들에 대한 민감도 분석을 BC (Benefit/Cost) 비율 변화에 대하여 실시한 결과, 설치비용, 전력판매단가, 할인율, 단가 증가율순으로 높은 변화율을 보였다. 본 연구의 결과는 태양에너지가 에너지 재활용이 가능한 농촌마을을 계획함에 있어서 정부의 적절한 지원정책과 에너지 잠재력이 높은 농촌마을을 선별한다면 매우 효과적인 결과를 얻을 수 있다는 것을 보여준 것으로 판단되었다.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.2
• /
• pp.11-18
• /
• 2012

Diesel fuel is expensive because transportation to remote areas adds extra cost, and it causes air pollution by engine exhaust. Providing a feasible economical and environmental solution to diesel generators is important. A hybrid system of renewable plants and diesel generators can benefit islands or other isolated communities and increase fuel savings. Renewable energy is, however, a natural source that produces a fluctuating power output. In this paper, hybrid power system of the marado lighthouse is proposed to supply stable power in the stand-alone hybrid power system. The proposed hybrid power system consists of the diesel generator, wind turbine, photovoltaic, fuel cell, and battery bank. To decrease the carbon emissions and find the optimization, the cost analysis of hybrid system is simulated using HOMER program and the optimized hybrid power system is designed.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.5
• /
• pp.647-654
• /
• 2009

Since the end of the 1990s, sewer pipe improvement works have been going on: most septic tanks have been thrown away and discarded. These discarded septic tanks amounts up to 370,000 based on the project plan 2005-2008: it is a serious squander of nation's resources, a contaminating means that buries toxins under soil, and a cause of a expensive waste. Research on recycling of discarded septic tank as a new resource is in urgent need. This research suggests plans to recycle discarded septic tank as a rainwater management facility, solutions to water cycle recovery in the limelight, and economic analysis of the plan. In the case of a recycling discarded septic tank as a rainwater management facility will socially benefit to support economical adequacy, discard cost saving of septic tank and water supply and sewage cost reduction will come out. Consequently a rainwater management facility converted from a discarded septic tank leads to decentralization of the rainwater management system, which anticipates a positive effect on recovery of urban water cycle.

• International Commerce and Information Review
• /
• v.8 no.3
• /
• pp.23-42
• /
• 2006

Services, despite the difficulty of its exact definition, can be defined as deeds, efforts, or performances by economical bodies, attributing to four unique characteristics - intangibility, inseparability, heterogeneity, and perishability. This study aims to research the global competition and problems of the local professional services, especially educational services and health services, and to suggest some devices for increasing the exportation of both educational services and health services. Educational services and health services were reserved in the multilateral negotiation to open the WTO parties' markets because of its national public benefits. But it is indispensable to open our local market by the bilateral FTA negotiation. Legal restrictions, therefore, related to both education and health should be erased according to the basic rule of the market competition, and it is advisable to control the national public benefit of these services by enacting the different legal systems. For recovering from minus balance of payment in the educational services or health services, furthermore, it is necessary to drive rather some offensive exporting policies than the defensive policy against supply from the foreign countries. In conclusion, the korean Foreign Trade Act and other relative acts should be revised, and both educational services and health services should be contained within the definition of "the international trade" for the governmental benefits of supporting the services exportation.

• International Journal of Human Ecology
• /
• v.2 no.1
• /
• pp.57-75
• /
• 2001

Since the Korean economic crisis in 1997, consumers are selecting goods that are more economical and more reasonably priced. Markets for wealthy people, however, have seldom been influenced by economic conditions. Consequently, 'noble marketing' is a new term that marketers should become acquainted with (Kim, 1998). The continuously expanding 'noble market' that generates high profit for marketers needs to be explored, especially the men's wear market. This study adopted a qualitative method (i.e., in-depth interview) with 16 male consumers each. These men who spent more than 3,600,000 won on apparel goods in 2000 and each man had purchased at least one item-suit, jacket, trousers, or coat-from a list of high-priced brands that were selected by the researcher. Findings imply that material or functional benefit of the high-priced apparel were not a critical determinant for choosing the brand. Rather, a socially well-established image for the brand name, especially in terms of psychological/symbolic appeal, played a more important role. This finding supported previous studies. Therefore, for high-priced men s wear, the role of promotion, including advertising or word of mouth, is critical; the image that advertisers should promote is one that characterizes the clothing, and ultimately the wearers, as dignified, legitimate, traditional, and upper class.

• Proceedings of the IEEK Conference
• /
• 2001.10a
• /
• pp.404-408
• /
• 2001

This paper focuses on the pilot-scale investigation of direct recycling of electric arc furnace (EAF) stainless steelmaking dust. The direct recycling of EAF dust is to make pellets with the mixture of the dust and the reducing agent carbon, then introduce the pellets to the EAF. The valuable metals in the dust are reduced and get into the steel as the alloying elements. Experiments simulating direct recycling in an EAF were performed using an induction furnace. But it seems difficult to reduce all metal oxides in the dust so that some metal reducing agents added in the late stage of reduction process. The valuable metals in the dust were reduced partly by carbon and partly by metal reducing agent for the economical concern. The recovery of iron, chromium and nickel from the flue dust and the amount of metal oxides in the slag were measured. The results showed that the direct recycling of EAF stainless steelmaking dust is practicable. It wes also found that direct recycling of flue EAF stainless steelmaking dusts does not affect the chemistry and quality of stainless steel produced in the EAF. It is benefit not only for the environmental protection but also for the recovery of valuable metal resources in this way.

• Korean Journal of Organic Agriculture
• /
• v.5 no.2
• /
• pp.93-104
• /
• 1997

In order to investigate the growth response of grasses to chitosan solution amended soil were studied from the standpoint of estimating the growth stimulating adequate concentrations of chitosan solution amended soil in each grass. Three species in this experiment used were orchardgrass, tall fescue and reed canarygrass. Six different concentrations of chitosan solution amended soil were 0%(control), 0.01%, 0.05%, 0.1%, 0.5% and 1.0%, respectively. The resulte obtained were as follows ; 1. Leaf area(LA), dry weight of leaf(LW), dry weight of shoot(SHW), biological yield(BY), C/f ratio and T/R ratio were significantly different between species. 2. Growth stimulating effect by chitosan solution amended soil were found in plant length(PL) and T/R ratios of grasses. 3. Adequate concentrations of chitosan solution amended soil were different between species. The highest values of yield components and dry weight of plant parts were obtained at 0.01% in orchardgrass, 0,05% in reed canarygrass and 1.0% in tall fescue, respectively. 4. The growth response of grasses to chitosan solution amended soil were different between species. Thus, an increase in leaf area(LA) and dry weight of leaf(LW) by chitosan solution amended soil was mainly contributed to increase in dry weight of shoot(SHW) and biological yield(BY) in orchardgrass. Chitosan solution amended soil also stimulated growth of shoot and increased in biological yield(BY) in tall fescue. In reed canarygrass contributed to increase in C/F ratios. 5. Adequate concentrations of chitosan solution amended soil for an economical benefit of cultivation and dry matter production of grasses were ranged from 0.01% to 0.05% levels.