• Structural Engineering and Mechanics
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• 제71권2호
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• pp.139-151
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• 2019

In a project schedule, it is possible to reduce the time required to complete a project by allocating extra resources for critical activities. However, accelerating a project causes additional expense. This issue is addressed by finding optimal set of time-cost alternatives and is known as the time-cost trade-off problem in the literature. The aim of this study is to identify the optimal set of time-cost alternatives using a multiobjective teaching-learning-based optimization (TLBO) algorithm integrated with the non-dominated sorting concept and is applied to successfully optimize the projects ranging from a small to medium large projects. Numerical simulations indicate that the utilized model searches and identifies optimal / near optimal trade-offs between project time and cost in construction engineering and management. Therefore, it is concluded that the developed TLBO-based multiobjective approach offers satisfactorily solutions for time-cost trade-off optimization problems.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권3호
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• pp.308-316
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• 2004

본 논문에서는 일반적인 상거래에서와는 다른 전자상거래 환경의 특성을 바탕으로 구매자와 판매자의 상거래에서 양자간 최대이익을 제공해 줄 수 있는 중개 에이전트 시스템을 제안하였다. 판매자와 구매자의 상거래를 통하여 얻을 수 있는 최적의 타협안은 어느 한쪽으로 이익이 치우치지 않고 양자간 이익의 합이 최대가 되는 제안으로 정의하였다. 중개 에이전트는 상품의 다중 속성을 고려하여 협상을 수행하며, 구매자와 판매자의 이익은 Multi Attribute Utility Theory(MAUT)를 이용하여 표현하였다. 중개 에이전트를 이용한 협상 과정은 협상에 참여한 구매자와 판매자의 협상 정보를 이용하여 정수계획법으로 모형화 하였다. 중개 에이전트 시스템과의 비교를 위하여 상호이익의 보장이라는 동일한 조건 하에서, 구매자와 판매자에이전트 사이의 상호작용을 이용한 협상 알고리즘의 하나인 trade-off mechanism을 적용하여 협상 시스템을 구현하였다. Trade-off mechanism에 의한 타협안의 경우 최적간을 보장하지 못하는 반면 중개 에이전트 시스템에 의한 타협안은 상대적으로 빠른 시간 내에 양자간 최대 이익을 제공하는 최적의 타협안을 보장해 주었다.

• 대한가정학회지
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• 제40권8호
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• pp.153-166
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• 2002

This study aims to reveal the influence of price increase in gasoline on household expenditure trade-off. The subjects were 651 households, acquired the first quarter of 1996 and 1997. This study shows the change of the auto fuel budget share in the same household and they were analyzed with the paired t-test, independent t-test. The results are as follows; 1) the price increase of auto gasoline resulted in the increase of its budget share, regardless of a household's true increase or decrease of income. 2) according to price increase in gasoline, the auto fuel budget share has been changed, therefore I divided these changes into three group on the base of it's degree of change. 3) In the group that had a decrease in auto fuel budget share compared to the degree of change, there was a trade-off between the increase in food and light & light water and the decrease of education and auto fuel budget share. Auto fuel in this group was used as discretionary good. 4) In the group that had a similar change in auto fuel budget share compared to the degree of change, there were no trade-off between expenditure items except auto fuel budget share and miscellaneous decrease. This group is the highest income group among the three groups. 5) In the group that had and increase of change in auto fuel budget share compared to the degree of change, there was a trade-off between the increase of eating-out and auto fuel, and the decrease of education and miscellaneous budget share. Auto fuel in this group was used as a discretionary good. 6) trade-off expenditure budget share showed a mixed effect between the influence of increase in gasoline price and influence of increase in true income.

• 한국병원경영학회지
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• 제11권2호
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• pp.61-86
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• 2006

Based on a previous literature about hospital capital structure(Shyam- Sunder & Myers, 1999), this study attempted comparison and analysis on whether the forecast of trade-off and pecking order theory could be validated in hospital's capital structure. First, this study analyzed whether hospitals follow the priority for each capital source as suggested by pecking order theory under lack of capital running in hospital. Next, it analyzed whether debt level is regressed on the average to target debt level so as to verify the validity of trade-off theory. Finally, it also analyzed possible associations between debt level and determinants of capital structure as adopted in static trade-off theory, so as to verify relative advantages of these two theories about hospital capital structure. The analysis over whole period showed that both trade-off theory and pecking order theory isn't supported particularly. This mean that each hospital's financing behaviors is different and that has not dominant financing behaviors. In the midst of separation of dispensary from medical practice, medical institutions in Korea first finances funds required using retained earnings and then use liabilities. however pecking order theory is supported, the preference of long-term liabilities and short-term liabilities is not clear. In addition, considering that debt level is in no average regression to target debt ratio, it is found that hospital capital structure following trade-off theory turns into that subject to pecking order theory via the separation of dispensary from medical practice.

• 보건행정학회지
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• 제16권4호
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• pp.24-47
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• 2006

Based on the findings of a study focused on medical institutions(Fama & French, 2002), this study determined possible causality between determinants of capital structure and liability level, while estimating targeted debt ratio. Moreover, it also examined hypotheses about the adjustment of targeted debt ratio and the of fundraising patterns, so that it verified the relative priority of trade-off theory and pecking order theory. First, profitability had positive(+) relationships with liability level, while investment opportunities had negative(-) relationships with liability level. This finding supported pecking order theory, and non-liability tax shield effects had negative(-) relationships with liability level as estimated in both trade-off theory and pecking order theory. Next, this study verified trade-off and pecking order theory at once by means of regression analysis about the variation of liability level in associations with disparity from targeted debt ratio and short-term fluctuation of profit and investment. As a result, it was noted that liability level became mean-reversed to targeted liability ratio but slowly, SO it was difficult to assert that such mean reverse may support trade-off theory. However, the finding that most of short-term fluctuations of profit and investment are absorbed into liabilities supported pecking order theory. On the other hand, it was found that the larger scale of medical institutions is more supportive of pecking order theory in the associations between liability level and profitability and the fundraising patterns than trade-off theory.

• 한국음향학회지
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• 제19권5호
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• pp.79-83
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• 2000

필터 설계에서 통과대역 파상 α/sub p/와 저지대역이 시작하는 주파수 w/sub s/에서의 저지대역 감쇠 α/sub s/가 주어질 때 필터 함수의 차수는 정수이기 때문에 저지대역 감쇠가 설계명세보다 △α/sub s/ 만큼 커진다. 본 논문에서는 트레이드 오프를 이용하여 초과된 저지대역 감쇠 △α/sub s/를 제거함으로써 극점-Q를 감소시키는 방법을 제안하고 필터 특성을 개선하였다. 또한 trade-off를 이용한 극점-Q 감소법을 변형된 Chebyshev 함수에도 적용하여 4가지 형태의 함수를 주파수 영역 및 시간 영역에서 특성을 비교 해석하였다. 트레이드 오프를 이용한 극점-Q 감소법은 필터의 특성에 직접적인 영향을 주는 극점-Q 값을 차수의 증가 없이도 최대 49.6%까지 감소하였다. 이로 인하여 트레이드 오프 이전의 Chebyshev 필터 함수에 비해 주파수 영역의 위상, 지연 특성 등이 개선되었고, 시간영역의 단위계단응답 특성에서 지연시간, 정착 시간이 감소하였다.

• 항공우주시스템공학회지
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• 제10권3호
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• pp.23-31
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• 2016

The intermediate mixing chamber is one of various methods for improving the regression rate and combustion efficiency of the hybrid rocket. The mixing chamber with its non-combustible material makes the propulsion performance increase, but it leads to a low fuel-loading density in the combustion chamber; therefore, this performance-related trade-off between the mixing chamber and the low fuel-loading density was studied. In this study, the trade-off was conducted by comparing the intermediate-mixing-chamber case with a w/o-mixing-chamber case. The small hybrid-sounding rocket is designed with internal ballistics for comparing the rocket length to the weight. In addition, an external ballistic analysis was conducted for comparing the performances of the w/- and w/o-mixing-chamber cases. As a result, the intermediate-mixing-chamber case shows that the length and the weight were decreased to 12 % and 8 %, respectively; furthermore, when compared with the normal cases, the estimated altitude result of the w/-mixing-chamber case was increased to approximately 75 m.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.131-143
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• 2002

In this paper hi-criterion quadratic fractional generalized solid transportation problem is studied. An algorithm is developed to obtain the time-cost trade-off pairs and hence identifies the optimum trade-off pairs giving the equal priority to both time and cost. A numerical example is illustrated to support the algorithm.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권2호
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• pp.184-188
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• 2014

There is a trade-off between read stability and writability under a full-/half-select condition in static random access memory (SRAM). Another trade-off in the minimum operating voltage between the read and write operation also exists. A new peripheral circuit for SRAM arrays, called a variation sensor, is demonstrated here to balance the read/write margins (i.e., to optimize the read/write trade-off) as well as to lower the minimum operation voltage for both read and write operations. A test chip is fabricated using an industrial 45-nm bulk complementary metal oxide semiconductor (CMOS) process to demonstrate the operation of the variation sensor. With the variation sensor, the word-line voltage is optimized to minimize the trade-off between read stability and writability ($V_{WL,OPT}=1.055V$) as well as to lower the minimum operating voltage for the read and write operations simultaneously ($V_{MIN,READ}=0.58V$, $V_{MIN,WRITE}=0.82V$ for supply voltage $(V_{DD})=1.1V$).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3096-3117
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• 2013

To execute the performance driven Grid applications, an effective and scalable workflow scheduling is seen as an essential. To optimize cost & makespan, in this paper, we propose a Scalable Cost-Time Trade-off (SCTT) model for scheduling workflow tasks. We have developed a heuristic algorithm known as Scalable Cost-Time Trade-off Scheduling (SCTTS) with a lower runtime complexity based on the proposed SCTT model. We have compared the performance of our proposed approach with other heuristic and meta-heuristic based scheduling strategies using simulations. The results show that the proposed approach improves performance and scalability with different workflow sizes, task parallelism and heterogeneous resources. This method, therefore, outperforms other methods.