• Membrane and Water Treatment
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• 제10권1호
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• pp.75-82
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• 2019

In a highly urbanized area, land availability is limited for the installation of space consuming stormwater systems for best management practices (BMPs), leading to the consideration of underground stormwater treatment devices connected to the stormwater pipe system. The configuration of a stormwater pipe network determines the hydrological and pollutant transport characteristics of the stormwater discharged through the pipe network, and thus should be an important design consideration for effective management of stormwater quantity and quality. This article presents a multi-objective optimization approach for designing a stormwater pipe network with on-line stormwater treatment devices to achieve an optimal trade-off between the total installation cost and the annual removal efficiency of total suspended solids (TSS). The Non-dominated Sorted Genetic Algorithm-II (NSGA-II) was adapted to solve the multi-objective optimization problem. The study site used to demonstrate the developed approach was a commercial area that has an existing pipe network with eight outfalls into an adjacent stream in Yongin City, South Korea. The stormwater management model (SWMM) was calibrated based on the data obtained from a subcatchment within the study area and was further used to simulate the flow rates and TSS discharge rates through a given pipe network for the entire study area. In the simulation, an underground stormwater treatment device was assumed to be installed at each outfall and sized proportional to the average flow rate at the outfall. The total installation cost for the pipes and underground devices was estimated based on empirical formulas using the flow rates and TSS discharge rates simulated by the SWMM. In the demonstration example, the installation cost could be reduced by up to 9% while the annual TSS removal efficiency could be increased by 4% compared to the original pipe network configuration. The annual TSS removal efficiency was relatively insensitive to the total installation cost in the Pareto-optimal solutions of the pipe network design. The results suggested that the installation cost of the pipes and stormwater treatment devices can be substantially reduced without significantly compromising the pollutant removal efficiency when the pipe network is optimally designed.

• 지식경영연구
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• 제17권2호
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• pp.205-229
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• 2016

Owing to the current economic downturn, one of the most important goals of the organizations who are actively involved in Information Technology Outsourcing (ITO) is the cost efficiency. We focus on supplier firm's domain understanding to make the cost efficiency; therefore, we examine how the disadvantages from lower domain knowledges affect outsourcing performance moderated by outsourcing ratio and knowledge change environments. That is, if clients can endure disadvantage from service providers' lower domain knowledge, they can achieve cost efficiency by choosing lower domain knowledge suppliers with less expensive cost. To examine performance gap depending on the environments, we applied 'A Learning Model of IT Outsourcing' which is suggested by previous literature. As a result, we suggest five strategies for clients to contract with suppliers which have lower domain knowledge: (1) Prepare the strategy to endure disadvantages from the early stage. (2) Make the strategy depending on outsourcing ratio. (3) Knowledge transfer between organizations is important. (4) Make a short-term contract if they do not have good environments for organizational learning. (5) Client's knowledge change environments are more important than those of supplier's. Finally, we offer various implications for clients and suppliers in IT outsourcing.

• 한국정보시스템학회지:정보시스템연구
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• 제26권2호
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• pp.143-164
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• 2017

Purpose The purpose of this study is to investigate to investigate the effects of cloud system on the efficiency improvement and cost-saving of production processes. It also tries to provide small- and medium-sized companies and IT practitioners with a practical guideline for a successful implementation of could systems. Design/methodology/approach This study was conducted by observing and analyzing a case of implementing a cloud system at a small-sized company having multiple job sites in terms of the improvement in data-sharing efficiency and cost-saving of production processes. Findings This study found that cloud system was an effective way of sharing data between and among production processes of geographically scattered job sites and thus, helped the company to remedy problems of work schedule and load-balance along sequential production processes. Cloud system also allowed the company to reduce the number of visits made by 3-inspectors to four job sites by 75% and the personnel cost related to inspectors' site visit.

• 한국환경보건학회지
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• 제21권4호
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• pp.56-62
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• 1995

Recently, the traffic noise around residences and schools has become a serious social problem with the increase of the amount of transportation. This study was performed to investigate the sound proof efficiency of windows for traffic noise. The results were as follows 1) The traffic noise in 19 sites among 22 sampling sites was higher value than 65 dB(A) being roadside environment standard level in the daytime when all windows were opened, while the noise in 22 sampling sites was transmitted below standard level when all windows were closed. 2) The transmission loss of sound level at single window and double windows were 10~25 dB(A) and 11~29 dB(A) respectively. 3) The transmission loss of sound level at sampled school with sound proof pannel was 7~8 dB (A), which was lower 2~7 dB(A) than the theoretical value of the influence assessment . 4) The construction cost of double windows was lower 28% even if include the cost of setting up air conditioner for the summer season and the power consuming cost for its operation than that of sound proof pannel for traffic noise. 5) The effect of transmission loss of windows was more influenced by airtight than materials of windows.

• 자원ㆍ환경경제연구
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• 제11권2호
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• pp.233-260
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• 2002

This paper tries to analyze the efficiency structure and regulatory effects in electric power industry by using total factor productivity and indices based on cost function method. This paper performed an empirical analysis on the efficiency improvement and optimal scale taking the cost aspect in electricity industry into account. By expanding the cost structure framework, this paper proposes the analytical method regarding the needs of technology regulation and presents the empirical results which can be verified. Hence, this work can play a key role in decision-making of the national power development and regulatory policy. The empirical result indicates that the electricity industry in Korea has been in the state of economies of scale until 1980s, However, due to sustained growth of power generation, economies of scale declined and subsided after 1980s and then diseconomies of scale is shown recent years. The analysis on the effect of technology regulation shows the national large-scale base-load power plant development-oriented policy until so far contributed substantial cost effect to the electricity industry. The empirical result indicates that the reserve requirement as one of means of technology regulation policy did not contribute to the economies of scale but positive effect on the total factor productivity in Korea.

• 대한토목학회논문집
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• 제28권1D호
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• pp.67-72
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• 2008

건설기계는 건설사업의 성공적인 수행을 위한 중요한 요인이다. 그리고 건설기계에 소요되는 비용이 건설공사비에서 차지하는 비중이 크다. 따라서 건설기계 비용의 산정은 건설계획 단계에서 중요한 업무이다. 이를 위해서 우리나라는 표준 품셈에 제시된 건설기계 시공능력 산정식을 이용하여 건설기계의 시간당 작업량을 계산하는 방식을 활용하고 있다. 그러나 건설기계의 성능은 개선되고 있으나 시공능력 산정식에서 활용되고 있는 작업효율은 이를 반영하지 못하는 실정이다. 이에 본 연구는 유압식 백호, 로우더, 덤프트럭을 대상으로 현장실사를 통해 작업효율을 실측하였다. 그 결과 백호와 로우더는 현재 활용중인 작업효율보다 현장실사 값이 높게 나타났으며, 덤프트럭은 낮게 나타났다. 본 연구결과를 바탕으로 건설기계의 작업효율 표준 산정식에 대한 정의가 수립되어야 하며, 체계적이고 장기적인 조사를 거쳐 작업효율의 개정이 필요할 것으로 사료된다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.113-118
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• 2007

이번 연구는, 실제 공사 현장에서 적용할 수 있는 프리캐스트 복합화 콘크리트 공법을 선정하였다. 현장에서 프리캐스트 복합화 콘크리트 공법의 실제 공사비와 철근콘크리트 공법에 적용되는 추정 공사비를 비교하였다. 고강도 콘크리트와 프리스트레스트 콘크리트의 사용함으로서, 50%이상의 콘크리트 양을 줄일 수 있었지만, 프리캐스트 콘크리트 복합화공법의 주된 비용인 생산비와 운송비를 포함한 재료비는 큰 차이가 없었다. 그러나 철근콘크리트인 경우, 철근과 거푸집 노무비가 30%를 차지하며 추가비용으로 비계, 가설공사가 큰 비중을 차지하는 철근콘크리트 공법이 프리캐스트 콘크리트 복합화 공법과 비교하여 2배정도의 시공비용이 소요된다. 위의 결과를 분석하면 프리캐스트 복합화 공법이 철근콘크리트 공법의 비용보다 11%의 훌륭한 비용절감 효과가 나타났다.

• 한국경영과학회지
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• 제29권3호
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• pp.79-98
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• 2004

Despite its contribution to the Korean medical service industry the question of how efficiently the Korean public hospitals have operated has been unresolved. This study gauges and analyzes the overall efficiency and the Malmquist productivity index in the industry over the period 1992 through 2001. In addition to cost efficiency. we also measure technical, allocative, pure technical and scale efficiencies. Furthermore. the Malmquist index is decomposed into efficiency and frontier changes. We identify several important factors which seem to have strong relationship with various inefficiency estimates. The results indicate that on average the public hospitals has wasted a significant amount of resources and costs over the period. Unlike many other industries, the low level of cost efficiency of the public hospital industry is mainly due to allocative inefficiency rather than technical inefficiency. The Maimquist productivity indices seem both due to the frontier change and efficiency change, but with more effect by the former. The results also indicate that the turnover of hospital beds has played an important role in determining efficiency and productivity of this important industry.

• KDI Journal of Economic Policy
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• 제28권1호
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• pp.49-93
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• 2006

본 연구는 은행과 보험 간의 겸업이 은행의 안정성과 효율성에 어떠한 영향을 미치는가를 실증분석하고 있다. 실증분석은 국내 모든 은행과 보험회사의 2000년부터 2004년까지의 5개년 자료를 가지고 Z-score 및 복합함수형태 (composite functional form) 모형을 사용하여 진행하였다. 안정성 분석결과는, 은행이 보험업을 겸영할 경우 겸업비중이 확대될수록 안전성은 저하됨을 보여주고 있다. 효율성 분석에서는, 전체 은행의 경우 은행이 보험업무의 겸업비중을 확대함에 따라 비용효율성은 감소하지만, 수익효율성은 증가하며, 결과적으로 이익효율성은 증대되는 것으로 나타났다.

• 한국건축시공학회지
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• 제1권1호
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• pp.135-142
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• 2001

This study is for the investigation of form using the aluminum-compound metal frame(Aluminum frame reinforced panel : AFR panel) which is improved in the capacity in the wall-concrete structure in steal of using the existing form which has problems such as, excessive exposure of cement, the loss of labor when it is constructed or disjointed, and it's economical efficiency compared with that of EURO Form. AFR panel passes the KS F 8006 test, and as a result of field test, it's displacement is satisfied with Specification. And using AFR panel is more economical than that of EURO Form because saving labor cost which plays a major part in cost saving in formwork is more effective in retrenching total cost than increment of material cost.