• Steel and Composite Structures
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• v.14 no.5
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• pp.431-451
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• 2013

The Big Bang-Big Crunch (BB-BC) optimization algorithm is developed for optimal design of non-linear steel frames with semi-rigid beam-to-column connections. The design algorithm obtains the minimum total cost which comprises total member plus connection costs by selecting suitable sections. Displacement and stress constraints together with the geometry constraints are imposed on the frame in the optimum design procedure. In addition, non-linear analyses considering the P-${\Delta}$ effects of beam-column members are performed during the optimization process. Three design examples with various types of connections are presented and the results show the efficiency of using semi-rigid connection models in comparing to rigid connections. The obtained optimum semi-rigid frames are more economical solutions and lead to more realistic predictions of response and strength of the structure.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.744-751
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• 2013

In this paper, Secant method is proposed to solve multi area economic dispatch (MAED) problem. Generator limits of all generators in each area are calculated at given area power demands plus export (or import) using secant method and the generator limits of all generators are modified as modified generator limits. Central economic dispatch (CED) problem is used to determine the output powers of all generators. Here, Secant method is applied to solve the CED problem. The proposed approach has been tested on two-area (two generators in each area) system and four-area (four generators in each area) system. It is observed from various cases that the proposed approach provides optimally best solution in terms of cost with tie line loss with less computational burden.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.335-338
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• 2004

Life-Cycle Engineering(LCE) is a decision-making methodology that considers environmental and cost needs during the product life-cycle. Environmental conscious design and manufacturing has become more and more important and it has been enforced by governmental regulations and used as trade restriction. LCE involves integrating environmental consideration into new product development including design, material selection, manufacturing processes and distribution of the product to the consumers, plus the end-of-life management such as disassembly, material recovery, remanufacturing of the product after discarding it. In this paper, a state-of-the-art survey of LCE is presented.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.339-342
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• 2018

The resent work is about the design and installation of the 60 URT heat pump according to the need. This design is eco-friendly, easily available, reduces maintenance and electricity cost. The dimensions of heat pump is $1500mm{\times}500mm{\times}1940mm$ (i.e length 1500 mm, width 500 mm and height 1940 mm) is installed on site. It can be operated with automation (PID) and controlled by sensors. The performance of and heat pump is evaluated experimentally by the monitoring system.

• Journal of Korean Association for Spatial Structures
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• v.19 no.3
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• pp.77-83
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• 2019

AU(A plus U-shaped) composite beam was developed for reducing the story height in the residential buildings, and saving the cosrtuction cost of floor structures. Structural performance and economic feasibility of the composite beam have been sufficiently approved through the structural experiments and the analytical studies. Fire safety for the practical application of the composite beam has also been verified through the fire resistance tests and the heat transfer analyses. In this study 2-points bending tests were performed on the four specimens already tested for fire resistance to evaluate the residual bending strength of AU composite beam after fire accident. The same bending test was performed on the one fresh specimen having the same section and span of the specimens for practically comparative study.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.2
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• pp.23-40
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• 2013

The natural environment restoration industry has been newly included in the environment area of engineering technology. Accordingly, the enactment of a standard of estimate for determining the 'Cost plus Fixed Fee' method has become necessary for the implementation and vitalization of natural environment restoration projects. The purpose of this study is to determine the standards for which the prices for engineering projects are calculated with respect to the enactment of an engineering project standard of estimate in the natural environment restoration field. These include the scope of the technological work, standard area, manpower requirements by technical grade that are necessary for carrying out the technological tasks. Relevant laws and regulations, systems and precedent case studies were investigated and analyzed to establish a price calculation standard. The overall results of the analysis were used and applied to questionnaires, public hearings, and expert delphi techniques. The study showed the following results： The scope of the technological work was categorized into 'Biotopes', 'Eco-corridors' and 'Ecological restoration'. The standard area was set up as $1,000m^2$ for 'Biotopes' and $5,000m^2$ for 'Eco-corridors' and 'Ecological restoration'. The manpower requirements by technical grade that are necessary for carrying out the technological tasks were determined. The suitability of the costs, standard area, manpower requirements by technical grade of ordered engineering projects that are determined by applying the standard of estimate for natural environment restoration that may be enacted pursuant to this study may be effectively investigated and analyzed. Moreover, further studies on the calculation of standard prices that can ensure the stability of natural environment restoration projects will be necessary.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4188-4206
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• 2016

Power control is widely used to reduce co-channel interference in wireless networks and guarantee the signal-to-interference plus noise ratio (SINR) of ongoing connections. This technique is also effective for wireless body area networks (WBANs). Although achieving satisfactory SINR is important for WBAN users, they may not be willing to achieve it at arbitrarily high power levels since power is a scarce resource in WBANs. Besides, for WBANs with different purposes, the QoS requirements and concern about the power consumption may be different. This motivates us to formulate the power control problem using the concepts from microeconomics and game theory. In this paper, the QoS objective is viewed as a utility function, which represents the degree of user satisfaction, while the power consumption is viewed as a cost function. The power control problem consequently becomes a non-cooperative multiplayer game, in which each player tries to maximize its net utility, i.e., the utility minus the cost. Within this framework, we investigate the Nash equilibrium existence and uniqueness in the game and derive the best response solution to reach the Nash equilibrium. To obtain the optimal transmission power in a distributed way, we further propose a utility-based and QoS-aware power control algorithm (UQoS-PCA). Tunable cost coefficient in UQoS-PCA enables this scheme to be flexible to satisfy diverse service requirements. Simulation results show the convergence and effectiveness of the proposed scheme as well as improvements over existing algorithm.

• Journal of the Korean Operations Research and Management Science Society
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• v.3 no.1
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• pp.31-46
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• 1978

Consider a time interval during which the demand for trips is fixed (e.g. the rush hour period). The traveller has a choice between various public modes, whose travel times and fares are fixed, and the automobile mode, for which travel time and cost depend on the volume of traffic flow on those roads, which are subject to congestion. We consider the equilibrium in terms of a representative travellerm, who choses for any trip the mode and route with the least combined money and time cost. When several (parallel) model or routes are chosen, then the combined cost of money and time must be equal among these. Our problem is first, to find the optimal flows of cars and of public mode carriers on the various links of their networks and second the optimal fares for trips by the variousmodes. The object is to minimize the total operating costs of the carriers and car plus the total time costs to travellers. The optimal fares are related to, but not identical with the dual variables of the underlying Nonlinear Program. They are equal to these dual variables only in the case, when congestion tolls on trips or on the use of specific roads are collected from automobile users. When such tolls are not collected, they must be passed on as subsidies to travellers using competing modes. The optimal fares of public modes are then reduced by the amounts of these subsidies. Note that subsidies are not a flat payment to public carriers, but are calculated on the basis of tickets sold. Fares and subsidies depend in general on tile period considered. They will be higher during periods of higher demand. When the assumption of fixed trip demand is relaxed, this tare system is no longer best, but only second best since too much traffic will, in general, be generated. The Free Rider Theorem states the following : Suppose road tolls can be charged, so that a best pricing system for public modes is posssible. Then there may exist free rides on some routes and modes, but never on a complete round trip.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.5
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• pp.1743-1745
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• 2015

Objective: To evaluate the efficacy and adverse effects of three dimensional conformal radiotherapy (3D-CRT) with tamoxifen in treating patients with postoperative malignant glioma. Patients and Methods: 60 patients of postoperative malignant glioma were randomly assigned into two groups, 30 patients were treated with 3D-CRT plus tamoxifen (treatment group), and the other 30 patients with 3D-CRT plus temozolomide (control group). All patients were radiated by 6MV X-ray, 2.0Gy per fraction, once daily, with a total dose (DT) of 56~60Gy. Tamoxifen was delivered at $60mg/m^2/d$, temozolomide was given at $75mg/m^2/d$. All patients were treated with concurrent radiotherapy. Results: One, 2, 3 year survival rates of treatment and control group were 63.3%, 30.0%, 23.0% and 70.0%, 33.3%, 26.7%, respectively (${\chi}^2=0.01$, 0.23, 0.09, P>0.05). The rate of thromboembolism in treatment group was 6.7%. Conclusion: Therapeutic efficacy of two groups was similar, but it was more cost-effective in treatment group, and toxicity did not increase.

• Journal of Korean Academy of Nursing
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• v.44 no.4
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• pp.418-427
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• 2014

Purpose: Objectives of this study were to investigate the association between efficiency and quality of health care in Long-term Care Hospitals (LTCH) and determine related factors that would enable achievement of both high efficiency and high quality at the same time. Methods: Major data sources were the "2012 Korean Assessment of Propriety by Long-term Care Hospitals" obtained from the Health Insurance Review & Assessment Service. Cost variables were supplemented by a National Tax Service accounting document. First, data envelopment analysis was performed by generating efficiency scores for each LTCH. Second, matrix analysis was conducted to ascertain association between efficiency and quality. Lastly, kruskal-wallis and mann-whitney tests were conducted to identify related factors. Results: First, efficiency and quality of care are not in a relationship of trade-offs; thus, LTCH can be confident that high efficiency-high quality can be achieved. Second, LTCH with a large number of beds, longer tenure of medical personnel, and adequate levels of investment were more likely to have improved quality as well as efficiency. Conclusion: It is essential to enforce legal standards appropriate to the facilities, reduce turnover of nursing staff, and invest properly in human resources. These consequences will help LTCH to maintain the balance of high efficiency-high quality in the long-run.