• 제목/요약/키워드: Means-Efficiency

검색결과 1,774건 처리시간 0.027초

K-means 알고리즘을 이용한 계층적 클러스터링에서의 클러스터 계층 깊이 선택 (Selection of Cluster Hierarchy Depth in Hierarchical Clustering using K-Means Algorithm)

  • 이원휘;이신원;정성종;안동언
    • 대한전자공학회논문지SD
    • /
    • 제45권2호
    • /
    • pp.150-156
    • /
    • 2008
  • 정보통신의 기술이 발달하면서 정보의 양이 많아지고 사용자의 질의에 대한 검색 결과 리스트도 많이 추출되므로 빠르고 고품질의 문서 클러스터링 알고리즘이 중요한 역할을 하고 있다. 많은 논문들이 계층적 클러스터링 방법을 이용하여 좋은 성능을 보이지만 시간이 많이 소요된다. 반면 K-means 알고리즘은 시간 복잡도를 줄일 수 있는 방법이다. 본 논문에서는 계층적 클러스터링 시스템인 콘도르(Condor) 시스템에서 K-Means 알고리즘을 이용하여 효율적으로 정보 검색을 하고 검색결과를 계층적으로 볼 수 있도록 구현하였다. 이 시스템은 K-Means Algorithm을 이용하였으며 클러스터 계층 깊이와 초기값을 조절하여 더 나은 성능을 보임을 알 수 있다.

생태효율성(Eco-efficiency)지표 개발을 통한 KTX와 새마을호 열차의 사용단계 환경성 평가에 관한 연구 (A Study on the Environmental Evaluation in Use Stage of KTX and Samaul Train : the Development of Eco-efficiency Indicator)

  • 최용신;천윤영;이건모;김용기
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2011년도 춘계학술대회 논문집
    • /
    • pp.1313-1320
    • /
    • 2011
  • World Business Council for Sustainable Development(WBCSD) is effort to achieve sustainable development in economic growth, environmental preservation and social development. Being this way, it is essential for developing evaluation tool which quantify to fulfill sustainable development. Eco-efficiency is one of the quantitative tools to evaluate environmental impact and economic aspect. Eco-efficiency, in general term, means creating more value of product or services with less impact to environment. It indicates as environmental impact in denominator and value of product or services in numerator. Eco-efficiency shows how much economic value reveals to unit environmental impact caused by product or service as an indicator. This study aims at developing eco-efficiency indicator of railway industry considering use stage among the entire life cycle stage of KTX and Saemaul train and also, figure out eco-efficiency value through indicator. Therethrough, it is enables to evaluate created value per environmental aspects. Since rail vehicles demands a lot of energy to transport people during use stage, the environmental impact is more significant than other lkfe cycle stages. Therefore, it quantified environmental indicator as CO2 emission and economic indicator as transportation record per a year with an annual income. This study contributes to be used as a tool for quantifying indicator of comparison evaluation in respect of rail vehicle in use stage.

  • PDF

국내 제약산업의 합병효과 분석 (Efficiency Effects of Mergers in the Korean Pharmaceutical Industry)

  • 이철행;조근태
    • 한국경영과학회지
    • /
    • 제42권3호
    • /
    • pp.35-49
    • /
    • 2017
  • The main objective of this paper is to empirically analyze the efficiency effects of mergers on Korean pharmaceutical firms and suggests managerial or policy implications for managers or policy makers. This study selects non-merging control firms close to the size of merging firms, as well as a set of merging firms, and measures the effects of mergers on efficiency three years before and after the merger using the non-parametric data envelopment analysis (DEA) method. To compare the differences of efficiency means among several groups, Wilcoxon rank sum test or Wilcoxon signed rank test is used. It showed that the long-term effects after the merger appeared partially. Furthermore, it was observed that there was no difference statistically in the efficiency between merging and non-merging firms. Also, there was no difference statistically in the efficiency between the pre- and post-merger periods. In conclusion, there was not any observed synergy effect through group (or affiliated) mergers between affiliates or related mergers for Korean pharmaceutical firms.

공업용수 투입의 기술적 효율성 분석 (The Study on the Technical Efficiency of Industrial Water in Manufacturing)

  • 민동기
    • 한국수자원학회논문집
    • /
    • 제41권6호
    • /
    • pp.597-603
    • /
    • 2008
  • 본 연구는 수자원정책의 효율성 제고를 위한 정책 방안 마련의 토대를 제공하고자 제조업체에서 투입요소로 사용하고 있는 공업용수의 기술적 효율성을 추정하였다. 이를 위하여 자료포락분석(DEA:Data Envelopment Analysis)기법을 이용하였으며 분석 결과에 의하면 공업용수의 기술적 효율성은 전 산업 평균이 0.407로 추정되어 모든 투입요소가 가변적인 경우의 연구 사례에 비하여 낮은 추정치를 보여준다. 이는 공업용수에 대한 비용이 다른 투입요소에 비하여 낮아 기업 경영진이 공업용수의 효율적인 활용 필요성에 상대적으로 둔감한 결과로 볼 수 있다. 그리고 낮은 기술적 효율성 추정치는 모든 투입요소가 효율적이라고 가정하고 분석한 기존 연구들의 가정에 한계가 있음을 보여 준다.

생산설비에서 에너지효율 산정 (Energy Efficiency Calculations of the Production Facilities)

  • 박형준;정찬수
    • 조명전기설비학회논문지
    • /
    • 제21권6호
    • /
    • pp.102-108
    • /
    • 2007
  • 원유가의 급등과 더불어 에너지자원에 대한 관심이 크게 증가 되었는데, 다양한 에너지관련 분야 중에서 먼저 선행되어야 하는 것은 기존의 설비에서 사용하고 있는 에너지가 효과적으로 사용되고 있는가를 판단하는 것이며, 이를 에너지 효율의 산정이라고 한다. 따라서 본 논문에서는 에너지의 주요 수요처중 하나인 제지 생산 플랜트의 한 공정에서 전력에너지와 열에너지에 대한 에너지효율을 계산하였다. 이때 전력에너지는 운전 중인 전동기의 부하에 따른 효율을 중심으로, 열에너지는 공정에서 입출력되는 열량을 중심으로 계산하였다. 즉 운전 중인 생산설비의 한 공정의 전력과 열에너지에 대해 각각 에너지효율을 산정하였으며 일부 에너지절감에 대한 방안도 제시하였다.

Effects of Technology Transfer Policies on the Technical Efficiency of Korean University TTOs

  • HAN, JAEPIL
    • KDI Journal of Economic Policy
    • /
    • 제40권4호
    • /
    • pp.23-45
    • /
    • 2018
  • The Korean government has provided various policy devices to boost technology transfers between academia and industry since the establishment of the Technology Transfer Promotion Act in 2000. Along with the enactment of the law, the Korean government mandated the establishment of a technology transfer office at national and public universities and encouraged technology transfer activities. Despite the quantitative expansion of technology transfer offices (TTOs), operational inefficiency was brought up. As a supplementary policy, the Korean government implemented a line of projects to support the labor and business expenses of leading TTOs. This research questions whether the project greatly affected the technical efficiency of TTOs. We analyze publicly available university panel data from 2007 to 2015 using a one-step stochastic frontier analysis. The results suggest that the program was marginally effective at shifting the technical efficiency distribution to the right on average, but it failed to maximize its impact by diversifying the policy means based on targets. The marginal effects of the program on technical efficiency differ according to the research capability and size of each school. We also compare technical efficiency against the licensing income at the start and end of the program. Technical efficiency increased for the leading TTOs, and both measures show improvements for unsupported TTOs. Our empirical results imply that diversifying the program for universities with different characteristics may have improved the effectiveness of the policy.

공공부문 정보보호 담당 조직의 운영 효율성 평가 -자료포락분석 기법을 중심으로 (Evaluating the Efficiency of Information Security Organizations in Public Sector Using DEA Models)

  • 박태형;윤기찬;문신용;임종인
    • 정보보호학회논문지
    • /
    • 제20권6호
    • /
    • pp.209-220
    • /
    • 2010
  • 공공부문 성과평가는 조직의 효율성 증진을 중요한 목적으로 삼고 있다. '투입 대비 산출'로 정의되는 효율성을 평가함으로써 향후 조직의 개선방향을 설정할 수 있다. 공공부문 효율성 평가에 유용한 자료포락분석(DEA) 기법을 적용하여 중앙부처 정보보호 담당 조직 21개 의사결정단위(DMU)에 대한 효율성 평가를 수행하였다. 본 연구 결과에 의하면, 평가대상 21 개 DMU의 효율성점수 평균이 50%를 약간 상회하고 있어 효율성이 매우 낮은 것으로 나타났으며, 21개 DMU를 '부'와 '청 및 위원회'로 구분 비교하였을 경우에도 비슷하게 나타나고 있어 비효율의 개선이 요구된다.

An Analysis of the Productive Efficiency and Competitive Strength of Container Ports using the DEA, Super-efficiency, and FDH Methods

  • Park, Ro-Kyung
    • 한국항만경제학회지
    • /
    • 제18권1호
    • /
    • pp.3-26
    • /
    • 2002
  • The purpose of this paper is to Investigate the productive efficiency and competitive strength of world container ports using the DEA, Super-efficiency, and FDH methods with the raw data from previous research by Jun et al.(1993). The super-efficiency measure examines the maximal radial change In input, outputs for an observation to remain efficient. Therefore, it provides a means of distinguishing between efficient observations, which would otherwise seem identical. FDH provides a good test mechanism for examining the practical implications of the choice available among alternative efficiency measures and orientations, because of the lack of convexity of its production possibility set. Both methods are complementary to DEA. This paper follows the traditional productivity analysis method overcoming the limitation of previous studies by using the DEA, FDH and Super-efficiency methods, and proposing in measure the relative competitive strength of worldwide container ports. The main empirical results of this paper are as follows: Firstly the ports of Singapore, Hongkong, Kilrung, Busan, Tokyo. and Longbeach were found to be efficient In the CCR model. The ports of Felixstowe, Bangkok, Singapore, Hongkong, Kilung, Busan, Tokyo, and Longbeach were found to be efficient in the BCC model. Secondly, super. efficiency rankings under CRS and input-oriented model are as follows: Longbeach, Keelung, Singapore, Busan, Tokyo, and Honkong. However, it was difficult In differenciate the rankings under the VRS and input-oriented model. due to major difficulties posed by the ports of Singapore, Hongkong, and Longbeach. Thirdly, the FDH method shows that the inefficient ports are Bremerhaven, Antwerp, Le Havre, Kobe, Seattle, New York The policy Implications of this study are as follows: Firstly, when port authorities want to measure the international competitive strength of container ports and enhance their productive efficiency, they should consider the traditional method as well as introducing the Super-efficiency and FDH methods. Secondly, according to the analysis results of the super-efficiency and FDH methods, poll authorities should recommend benchmarks ports and dominated ports as reference ports in order to enhance the productive efficiency of their container ports that have an efficiency rating of less than 1. Efficient ports whose efficiency ratings are over 1 in the Input-oriented Super-efficiency model should also consider the usage of input and output elements used by more efficient ports.

  • PDF

수소 첨가에 따른 30kW급 가스엔진 발전기의 발전효율 및 질소산화물 배출량 특성 연구 (A Study on the Generating Efficiency and NOx Emissions of a 30kW Gas Engine Generator with Hydrogen Addition)

  • 차효석;김태수;엄태준;전광민;송순호
    • 한국수소및신에너지학회논문집
    • /
    • 제22권3호
    • /
    • pp.313-318
    • /
    • 2011
  • This study is about characteristics of generating efficiency and $NO_x$ emissions of a 30 kW gas engine generator in case of using model biogas with hydrogen addition. In this case, both generating efficiency and $NO_x$ emissions are lower than the case of using urban gas (LNG). However, generating efficiency and $NO_x$ emissions are higher than the case of using model biogas only. It means that adding hydrogen which has a high flame propagation velocity has the possibility to improve the generating efficiency, but simultaneously it is also able to increase the $NO_x$ emissions of a gas engine generator.

박막의 조성비율에 따른 유기태양전지의 효율성 연구 (A Study about the Efficiency of Organic Photovoltaic Device as a function of the Material Concentration)

  • 김승주;이동근;박재형;공수철;김원기;류상욱
    • 반도체디스플레이기술학회지
    • /
    • 제8권3호
    • /
    • pp.1-5
    • /
    • 2009
  • In this study, we have shown the power conversion efficiency of organic thin film photovoltaic devices utilizing a conjugated polymer/fullerene bulk-hetero junction structure. We use MDMO-PPV(Poly[2-methoxy-5-(3,7-dimethyloctyloxy -1,4-phenylenevinylene) as an electron donor, PCBM([6,6]-Phenyl C61 butyric acid methyl ester) as an electron accepter, and PEDOT:PSS used as a HTL(Hole Transport Layer). We have fabricated OPV(Organic Photovoltaic) devices as a function of the MDMO-PPV/PCBM concentration from 1:1 to 1:5. The electrical characteristics of the fabricated devices were investigated by means of I-V, P-V, F·F(Fill Factor) and PCE(power conversion efficiency). The power conversion efficiency was gradually increased until 1:4 ratio, also the highest efficiency of 0.4996% was obtained at the ratio.

  • PDF