• Journal of Information Processing Systems
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• v.13 no.3
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• pp.618-629
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• 2017

Mobile nodes can't always connect each other in DTNs (delay tolerant networks). Many DTN routing protocols that favor the "multi-hop forwarding" are proposed to solve these network problems. But they also lead to intolerant delivery cost so that designing a overhead-efficient routing protocol which is able to perform well in delivery ratio with lower delivery cost at the same time is valuable. Therefore, we utilize the small-world property and propose a new delivery metric called multi-probability to design our relay node selection principles that nodes with lower delivery predictability can also be selected to be the relay nodes if one of their history nodes has higher delivery predictability. So, we can find more potential relay nodes to reduce the forwarding overhead of successfully delivered messages through our proposed algorithm called HESnW. We also apply our new messages copies allocation scheme to optimize the routing performance. Comparing to existing routing algorithms, simulation results show that HESnW can reduce the delivery cost while it can also obtain a rather high delivery ratio.

• Computers and Concrete
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• v.17 no.5
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• pp.629-638
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• 2016

Optimization of the concrete mixture design is a process of search for a mixture for which the sum of the cost of the ingredients is the lowest, yet satisfying the required performance of concrete. In this study, a statistical model was carried out to model a cost effective optimal mix proportioning of high strength self-compacting concrete (HSSCC) using the Response Surface Methodology (RSM). The effect of five key mixture parameters such as water-binder ratio, cement content, fine aggregate percentage, fly ash content and superplasticizer content on the properties and performance of HSSCC like compressive strength, passing ability, segregation resistance and manufacturing cost were investigated. To demonstrate the responses of model in quadratic manner Central Composite Design (CCD) was chosen. The statistical model showed the adjusted correlation coefficient R2adj values were 92.55%, 93.49%, 92.33%, and 100% for each performance which establish the adequacy of the model. The optimum combination was determined to be $439.4kg/m^3$ cement content, 35.5% W/B ratio, 50.0% fine aggregate, $49.85kg/m^3$ fly ash, and $7.76kg/m^3$ superplasticizer within the interest region using desirability function. Finally, it is concluded that multiobjective optimization method based on desirability function of the proposed response model offers an efficient approach regarding the HSSCC mixture optimization.

• Knowledge Management Research
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• v.17 no.2
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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.

• Journal of Environmental Science International
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• v.27 no.9
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• pp.803-807
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• 2018

This study evaluated the duck growth performance and the economic benefits on using illite as a feed additive for ducks. Illite powder at three levels (0%, 1%, and 1.5%) was added to commercial duck diets, and fed to 180 one-day-old ducks (Pekin, 3 replicates, 20 ducks per pen) using a randomized block design for 39 days. During the experimental period, there were no significant growth performance differences between treatments (p>0.05), except with the feed conversion ratio (p<0.05), for all periods (8-39 days). In addition, the dietary supplementation of 1% and 1.5% illite did not significantly improve (p>0.05) Feed Intake Cost (FIC), Weight Gain Value (WGV), Meat Production Cost (MPC), Economic Efficiency (EE), Profitability (P), or cost benefit ratio for 8 to 21 d, 22 to 39 d, and 8 to 39 d. However, the differences in meat production cost and profitability between treatments were statistically significant (p<0.05) for all periods (8-39 d). In conclusion, adding 1% and 1.5% illite to duck diets is not beneficial for improving either the duck growth performance or the economic indicators.

• Korean Journal of Construction Engineering and Management
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• v.6 no.1 s.23
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• pp.162-168
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• 2005

Index adjusted ratio method has been widely utilized in public construction sector for contract sum adjustment by price fluctuation. In this method, the Production Price Index are used for the base ratio, but the PPI can't reflect the character of construction project in respect of the selected items and weight. In this research we prove the problem of using the index adjusted ration method in contact sum adjustment by price fluctuation, and improve it by using the construction cost index, which has the property of construction project. And we figure out the efficiency of the proposed method by case study.

• Journal of the Korean Solar Energy Society
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• v.28 no.6
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• pp.70-77
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• 2008

The purpose of this study evaluates a feasibility and economical efficiency of new renewable energy. According as weather change is serious problem now days, every people make attention to the reduction of greenhouse gas. The revitalization of new renewable energy creates the variety of energy source, stability of energy supply and reduction of greenhouse gas. In this study evaluates a feasibility and economical efficiency from new renewable energy of various photo voltaics, wind power, small hydro and biogas. Feasibility does in standard of technical characteristic, politic support, marketability, establishment present condition and development aim. Economical efficiency does in standard of developmental unit cost, utilization factor, equipment life, politic support cost, interest ratio. The results of this study were as follows photo voltaics, wind, small hydropower, biogas in order feasibility is high. Developmental unit cost, utilization factor, equipment life, politic support cost and analyzed the relationship of interest ratio fluctuation and economical efficiency. From all new renewable energy the utilization factor most is important in economical efficiency but necessary utilization factor is difficult because environmental problem.

• Korean Journal of Agricultural Science
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• v.28 no.2
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• pp.132-146
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• 2001

Rice cultivation is not only the main resource of farm income and staple food but also the root of cultural life of Korean people. Korean government has carried out irrigation water development with heavy investment to cope with water shortage in rice fanning as a link of the five years economic development plans. In spite of the continuous accomplishment of irrigation water development, the marginal benefits-costs of irrigation water has not been studied. Owing to the government full support for the operation and maintenance of irrigation facilities, price of irrigation water as a membership fee could not be formed as the municipal and industrial water prices. Accordingly this study is aimed at identifying firstly the marginal benefits-cost of irrigation water, secondly deriving the macro-econometrics models as supply and demand functions of irrigation water and thirdly examining the marginal benefits-cost ratio. The trends of supply and demand prices of irrigation water were estimated annually. Considering the marginal benefits-cost ratio as 1.3, it was identified that additional irrigation water development projects still have an economic feasibility under the present economic situation in Korea.

• Membrane and Water Treatment
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• v.6 no.6
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• pp.451-476
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• 2015

Membrane distillation (MD), which can utilize low-grade thermal energy, has been extensively studied for desalination. By incorporating solar thermal energy, the solar membrane distillation desalination system (SMDDS) is a potential technology for resolving the energy and water resource problems. Small-scale SMDDS (s-SMDDS) is an attractive and viable option for the production of fresh water for small communities in remote arid areas. The minimum-cost design and operation of s-SMDDS are determined by a systematic method, which involves a pseudo steady state approach for equipment sizing and the dynamic optimization using overall system mathematical models. The s-SMDDS employing three MD configurations, including the air gap (AGMD), direct contact (DCMD) and vacuum (VMD) types, are optimized. The membrane area of each system is $11.5m^2$. The AGMD system operated for 500 kg/day water production rate gives the lowest unit cost of $5.92/m^3$. The performance ratio and recovery ratio are 0.85 and 4.07%, respectively. For the commercial membrane employed in this study, the increase of membrane mass transfer coefficient up to two times is beneficial for cost reduction and the reduction of membrane heat transfer coefficient only affects the cost of the DCMD system.

• Korean Journal of Clinical Pharmacy
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• v.31 no.1
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• pp.1-11
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• 2021

Objective: This study aimed to overview and assess the effectiveness of the policies and regulations that have governed new drug access in Korea, and to propose policies to enhance patient access to drugs, particularly for new innovative medicines. Methods: We approached drug access issues in two perspectives: approval lag (or availability) and reimbursement lag (or affordability). The issues were identified and evaluated through the review of literature, public documents, reports published by the government agencies and private organizations, and news articles. Results: To shorten approval lag, it is recommended to hire and train more reviewers at the Ministry of Food and Drug Safety. Increasing user fees to a realistic level can facilitate this process. To reduce reimbursement lag, flexible incremental cost-effectiveness ratio threshold, alternative cost-effectiveness evaluation, and establishment of funding source other than the national health insurance are identified as the areas to be improved. Conclusion: The current policies and regulations had to be supplemented by new systems to drastically promote patient accessibility to new drugs, consequently in order to promote national public health.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.437-446
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• 2005

Recently as people's values are changing from development phase into running stage after quality of life, so that the needs of environmentally friendly construction are gradually increasing. Also populace discontent about the pollution during construction process such as the noise and vibration caused by construction machinery is increasing. Even though it is impossible to eliminate the construction pollution fully, it is necessary to make efforts to reduce construction pollution to a minimum. In terms of construction site operating, the first possible step for solving these matters directly is that the necessary sum of expenses must be secured as the environmental management costs in the conceptual phase. However, in fact, the environmental management costs have not been secured in the budget. Generally it is the major reason not arising proper activities to prevent the pollution in the construction site. The purpose of this research is to suggest the efficient budgeting method regarding Environmental management costs to ensure the necessary sum of environmental management expenses. To provide an efficient budgeting method, interviews with the person in charge of environment management was conducted. 78 construction sites was surveyed and environmental management costs were analyzed through their historical data from the survey. According to the results of analysis, the ratio of environmental management costs is revealed 0.45% of construction cost as average comparing 0.2% of legal limit. And usually the environmental management cost was appropriated into the safety management budget. So it is needed to isolate environmental management budget securely and modify the ratio of Environmental conservation Costs in Construction Technology Management Act.