• Title/Summary/Keyword: Decision-Making Models

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실시간 재배치를 통한 카쉐어링 서비스 최적화에 관한 연구 : PSO 방법론 기반으로 (The Optimization of One-way Car-Sharing Service by Dynamic Relocation : Based on PSO Algorithm)

  • 이건영;이형석;홍요한;고성석
    • 산업경영시스템학회지
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    • 제39권2호
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    • pp.28-36
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    • 2016
  • Recently, owing to the development of ICT industry and wide spread of smart phone, the number of people who use car sharing service are increased rapidly. Currently two-way car sharing system with same rental and return locations are mainly operated since this system can be easily implemented and maintained. Currently the demand of one-way car sharing service has increase explosively. But this system have several obstacle in operation, especially, vehicle stock imbalance issues which invoke vehicle relocation. Hence in this study, we present an optimization approach to depot location and relocation policy in one-way car sharing systems. At first, we modelled as mixed-integer programming models whose objective is to maximize the profits of a car sharing organization considering all the revenues and costs involved and several constraints of relocation policy. And to solve this problem efficiently, we proposed a new method based on particle swarm optimization, which is one of powerful meta-heuristic method. The practical usefulness of the approach is illustrated with a case study involving satellite cities in Seoul Metrolitan Area including several candidate area where this kind systems have not been installed yet and already operating area. Our proposed approach produced plausible solutions with rapid computational time and a little deviation from optimal solution obtained by CPLEX Optimizer. Also we can find that particle swarm optimization method can be used as efficient method with various constraints. Hence based on this results, we can grasp a clear insight into the impact of depot location and relocation policy schemes on the profitability of such systems.

공간최적화 모델을 활용한 환경계획의 공간화 방안 (Suggestion for Spatialization of Environmental Planning Using Spatial Optimization Model)

  • 윤은주;이동근;허한결;성현찬
    • 한국환경복원기술학회지
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    • 제21권2호
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    • pp.27-38
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    • 2018
  • Environmental planning includes resource allocation and spatial planning process for the conservation and management of environment. Because the spatialization of the environmental planning is not specifically addressed in the relevant statutes, it actually depends on the qualitative methodology such as expert judgement. The results of the qualitative methodology have the advantage that the accumulated knowledge and intuition of the experts can be utilized. However, it is difficult to objectively judge whether it is enough to solve the original problem or whether it is the best of the possible scenarios. Therefore, this study proposed a methodology to quantitatively and objectively spatialize various environmental planning. At first, we suggested a quantitative spatial planning model based on an optimization algorithm. Secondly, we applied this model to two kinds of environmental planning and discussed about the model performance to present the applicability. Since the models were developed based on conceptual study site, there was a limitation in showing possibility of practical use. However, we expected that this study can contribute to the fields related to environmental planning by suggesting flexible and novel methodology.

산업기술개발의 불확실성에 따른 금융지원의 역할분담에 관한 이론적 고찰 (Theoretical Background of Division of Role in Technology Financing Based on Uncertainty Implied in Industrial Technology Development)

  • 김선근
    • 기술혁신연구
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    • 제5권1호
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    • pp.206-222
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    • 1997
  • The conventional analysis with which justifies government intervention of the private sector's innovation activities is the market failure approach. According to such analysis, fund allocation through autonomous market mechanisms is not optimal in technology financing because of the disparity between the desirable level of investment for society as a whole and that for private firms. To optimize the fund allocation, public policies such as subsidy, preferencial loan and venture capital investment programs are designed for technology development projects performed by private firms. They, however, have not been effective in increasing private investment for such projects. In most cases, it was found that little considerations given to the relationship between uncertainty embodied in technology development projects and each types of financing. With respect to optimizing fund allocation, technology development projects should be financed by different means according to their probability of success and the expected value of technology. Employing various theoretical models on financing decision-making we verify here that technology development projects to be supported by commercial banks or venture capital institutions is limited contingent upon levels of uncertainty adn expected value. Under the assumption that financial institutions are risk averse, loan or investment can be available only if the probability of success of the project is higher than the probability premium and the current market rate of interest. Therefore, the projects that have lower probability of success and/or small expected return are excluded from commercial loan or investment programs. However, the remaining projects, whose probability of success is low but with high expected return, may be applied under government subsidy programs. To achieve optimality of fund allocation and to activate technology financing, we conclude that there should be a systematic division of role among financial institutions including government commercial banks, and venture capital institutions.

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활 전복 수입에 의한 전복허피스바이러스감염증 (abalone herpes-like virus) 유입 위험평가 (A Stochastic Model to Quantify the Risk of Introduction of Abalone Herpes-like Virus Through Import of Abalones)

  • 박선일
    • 한국임상수의학회지
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    • 제31권1호
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    • pp.40-45
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    • 2014
  • Abalone herpes-like virus (AbHV) is a fatal disease of abalones that impose severe economic impacts on the industry of infected regions due to high mortality. The aim of this study was to quantify the risk of introducing AbHV into Korea through the importation of live abalones for human consumption by import risk analysis (IRA). Monte Carlo simulation models were developed to provide estimates of the probability that a ton of imported abalone contains at least one AbHV-infected individual, using historical trade data and relevant literatures. A sensitivity analysis with 5,000 iterations was also conducted to determine the extent to which input parameters affect the outcome of the model. Although many uncertainties were present in the data, the results indicated that, if 5,000 tons of abalone were imported from a hypothetical exporting country with low prevalence of AbHV (model 1), there would be at least one AbHV-infected abalones in 4,816 of those tons (96.3%), while there would be at least one AbHV-infected abalones in 100% of those tons imported from country with high prevalence (model 2). Sensitivity analysis indicated that for model 1, prevalence was the strongest influence factor on the predicted number of infections. For model 2, background mortality and washing to reduce the risk of surface contamination during processing were the major contributing factors. Risk management strategies need to be enforced to reduce the risk of AbHV introduction in that at least one infected abalone would remain in a consignment from country even with a low prevalence of AbHV infection. The methodology and the results presented here will contribute to improve the development of AbHV management program, and with more accurate data this IRA model will aid science-based decision-making on mitigation strategies to reduce the risk of AbHV introduction in Korea.

시스템 다이내믹스를 이용한 녹색건축인증제도 활성화 정책의 실효성 평가 (A Dynamic Approach for Evaluating the Validity of Boosting Pocliies for Green Standard for Energy and Environmental Design Certification)

  • 김정화;이현수;박문서;이슬비
    • 한국건설관리학회논문집
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    • 제17권1호
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    • pp.28-39
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    • 2016
  • 건물부분의 온실가스 감축을 위하여 2002년 정부는 녹색건축인증제도(G-SEED Certification)를 도입하였다. 그러나 정부의 각종 활성화정책에도 불구하고 공동주택부분의 인증건수는 전체 공동주택 사업승인건수의 1% 내외에 불과한 실정이다. 이러한 상황에서 정부의 정책은 대부분 공급자를 대상으로 하고 있으며, 정책개선 방안에 대한 연구도 대부분 공급자를 중심으로 이루어지고 있음을 알 수 있다. 하지만 주택시장은 시장의 참여자인 수요자와 공급자의 상호영향을 통해 작동되기 때문에 한쪽에 치우친 시각이 아닌 그들의 포괄적인 관계과 동태성을 고려해야할 필요가 있다. 따라서 본 연구에서는 녹색건축인증 공동주택시장을 수요자와 공급자의 의사결정을 토대로 분석하여, 시스템다이내믹스 연구 모델을 작성한다. 그리고 해당 모델에서 현재 시행중인 정부의 인증 활성화정책이 어떻게 작용하는지 살펴봄으로써 그 실효성을 분석하고자 한다. 이를 통해 향후 녹색건축인증제도의 활성화 정책 방향제시를 위한 기초를 마련할 수 있을 것이라 기대할 수 있다.

단계적 회귀법과 자료봉합분석을 이용한 변수선택기법의 개발 (Development of Variable Selection Technique using Stepwise Regression and Data Envelopment Analysis)

  • 정민의;유성진
    • 한국정보과학회논문지:소프트웨어및응용
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    • 제41권8호
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    • pp.598-604
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    • 2014
  • 본 연구는 주요변수를 선정하는 기법을 개발하기 위해서 단계적 회귀와 변수들의 효율성을 평가하기 위해 사용되는 자료봉합분석을 결합한 새로운 방법을 제안하였다. 이를 위해서 먼저 단계적 회귀를 이용하여 중요 변수들을 일차적으로 선정하고, 선정된 각 변수들의 중요도를 이해하기 위해 귀무가설을 세웠고, 중요 변수를 선택하기 위해 Kruskal-Wallis 검정을 사용했다. 또한 해당되는 변수를 Conover-Inman 검정을 사용하여 변동이 발생하는 각 변수들의 우선순위를 결정하였다. 따라서 그 결과, 많은 변수들과 DEA(Data Envelopment Analysis)의 한계를 극복하기 위해 원래 계획된 변수들 중 기준에 의해 원래 유지된 변수와 높은 연관성을 가진 변수들을 남기는 방식으로 변수를 선정하는 기법을 개발한 Jenkins의 기존연구에서는 I2, I4, I5, I6 변수가 누락되었고 I1, I3 변수만이 DEA에 사용되었지만, 본 논문에서 제안된 모델의 효율성 결과로는 I2와 I4 변수를 각각 유지하였다. 본 연구는 다른 문헌에서 단계적 변수의 선택을 보여주기 위해 같은 데이터 집합을 사용하였는데, 여기서 Jenkins의 연구와 같이 변수 I6과 I1, I2를 삭제하였고, I3, I4, I5는 유지하였다. 결론적으로 단계적 회귀 DEA 모델을 사용하여 긴 계산적 절차 없이 변수 선택이 가능함을 발견했으며 기존 연구의 데이터를 적용하여 제안된 모델을 검증하였다. 개발한 DEA모델 결과는 상호 변수에 따라 포함되거나 생략할 수 있기 때문에 실제 현실 상황에서의 지식과 경영적 판단에 매우 유용할 것이다.

Evaluation of Focal Bone Mineral Density Using Three-dimensional Measurement of Hounsfield Units in the Proximal Humerus

  • Moon, Young Lae;Jung, Sung;Park, Sang Ha;Choi, Gwi Youn
    • Clinics in Shoulder and Elbow
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    • 제18권2호
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    • pp.86-90
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    • 2015
  • Background: Although there are several methods for evaluating bone quality, Hounsfield units (HU), a standardized computed tomography (CT) attenuation coefficient, provide a useful tool for estimating focal bone mineral density (BMD). The aim of this study is to investigate the HU for evaluating the degree of osteoporosis in greater tuberosity with regard to anchor positioning. Methods: Forty patients diagnosed as normal on shoulder CT were included and categorized according to age and gender. Axially sectioned CT images were processed to 3-dimensional models containing information about bone quality using Mimics (14.11 platform v14.1.1.1 Materialise). Three-dimensional anchors were simulated and positioned according to 6 regions of interest (ROI) in the greater tuberosity classified using Tingart's system. Mean HU of intra-anchor volumes in the 6 regions was measured. Results: A significant decrease in HU was observed with increasing age (p=0.0001) and menopause (p<0.001). A significant difference in HU was found between male and female groups with males showing the higher values (p=0.0001). HU of proximal areas of ROI was higher than those of distal areas (p<0.005). However, although mean HU of distal posterior ROI showed the lowest values, no statistically significant difference was found between anterior, middle, and posterior regions (p=0.087). Conclusions: Mean HU of ROIs provides a tool for preoperative assessment of focal BMD, which is a factor of suture anchor stability and can be used to aid decision-making regarding secure anchor positioning for rotator cuff repair. Our data support that the most secure point is the proximal regions of ROI.

자료포락분석을 이용한 서울시 간선버스노선 효율성 평가 (A DEA(Data Envelopment Analysis) Approach for Evaluating the Efficiency of Exclusive Bus Routes)

  • 한진석;김혜란;고승영
    • 대한교통학회지
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    • 제27권6호
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    • pp.45-53
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    • 2009
  • 서울시의 버스체계개편 시행 후 약 4년이 지난 현재 대중교통 이용승객의 증가에도 불구하고 서울시의 재정부담은 크게 개선되지 못하였다. 이에 서울시는 버스의 경쟁력을 강화하고 효율성을 제고하기 위한 정책들을 수립할 계획이며, 이러한 정책의 효과를 객관적으로 평가하기 위해서는 버스수단 경쟁력의 기반이 되는 노선의 효율성 추정과 이에 영향을 미치는 요인들의 분석이 요구된다. 본 연구에서는 2008년 서울시 간선버스 노선의 자료와 DEA 모형의 하나인 BCC 모형을 이용하여 각 노선의 효율성을 추정하였다. 효율성 추정시 각 노선은 차량대수, 노선거리, 정류장개수, 배차간격, 운영비를 투입하여 승객수와 수익금을 산출하는 것으로 가정하였다. 투입지향 BCC 모형으로 분석한 결과, 평가노선 18개 중 규모수익불변(CRS)인 노선은 총 2개이며, 나머지 16개 노선은 규모수익체증(IRS)인 노선으로 분석되었다. 또한 분석에 사용된 요소들이 효율성 점수에 미치는 영향을 파악하기 위하여 토빗회귀분석을 수행한 결과, 현재 간선버스에 가장 큰 영향을 미치는 변수는 배차간격인 것으로 분석되었다.

DEA와 SNA를 이용한 효율적인 컨테이너 터미널의 영향력에 관한 연구 (The Influence of Efficient Container Terminals Using DEA and SNA)

  • 손용정
    • 한국항만경제학회지
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    • 제31권3호
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    • pp.155-166
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    • 2015
  • 본 논문은 효율적인 컨테이너 터미널의 영향력을 평가하기 위해 광양항과 부산항 컨테이너 터미널을 분석대상으로 선정하였다. 연구방법은 DEA분석(CCR, BCC모형) 후 DMU를 노드로 하고, DEA(BCC모형)의 참조집단과 람다값을 이용하여 사회 네트워크를 생성하고 아이겐벡터 중심성 분석에 의해 효율적인 DMU들의 영향력을 분석하였다. 분석결과는 첫째, DEA분석 결과 CCR효율성은 부산항의 PNC, HJNC, HPNT 컨테이너 터미널이 효율성 1이고, BCC효율성은 부산항의 신감만부두, 우암부두, PNC, HJNC, HPNT, BNCT 컨테이너 터미널이 효율성 1이다. 둘째, SNA분석 결과 아이겐벡터 중심성 분석에 의하면 HJNC터미널이 0.515로 가장 많이 참조되고 있는 컨테이너 터미널로 영향력이 가장 높은 것으로 볼 수 있다. PNC터미널이 0.512, 우암부두가 0.379, 순이고 광양항의 CJ대한통운 전체 영향력에서는 4위이나, 광양항 컨테이너 터미널 중에서는 0.256으로 가장 영향력있는 컨테이너 터미널이다.

응급의료센터 체류시간 최적화 (A Stay Time Optimization Model Emergency Medical Center (EMC))

  • 김은주;임지영;류정순;조선희;배나리;김상숙
    • 가정∙방문간호학회지
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    • 제18권2호
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    • pp.81-87
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    • 2011
  • Purpose: The aim of this study was to estimate optimization model of stay time in EMC. Methods: Data were collected at an EMC in a hospital using medical records from June to August in 2007. The sample size was 8,378. The data were structured by stay time for doctor visit, decision making, and discharge from EMC. Descriptive statistics were used to find out general characteristics of patients. Average mean and quantile regression models were adopted to estimate optimized stay time in EMC. Results: The stay times in EMC were highly skewed and non-normal distributions. Therefore, average mean as an indicator of optimal stay time was not appropriate. The total stay time using conditional quantile regression model was estimated about 110 min, that was about 166 min shorter than estimated time using average mean. Conclusion: According to these results, we recommend to use a conditional quantile regression model to estimate optimal stay time in EMC. We suggest that this results will be used to develop a guideline to manage stay time more effectively in EMC.

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