• Structural Engineering and Mechanics
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• v.71 no.2
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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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.179-185
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• 2015

The main objective of thermal design for a space-borne FPA(Focal Plane Assembly) is to provide stable thermal environment during imaging operation and thus maintain the image quality. An FPA must be maintained within its operating temperature range and cooled down to its initial temperature soon enough for the next imaging operation. This paper describes the study result on performing trade-off studies for FPA thermal design by using simplified thermal node analysis about FPA preliminary design. It also describes the verification results of the study by comparing thermal analysis results and trade-off study results. According to results, we can conclude that this approach is useful for simple and quick trade-off studies without thermal analysis based on thermal math models.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.45-52
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• 2021

The capital structure is one of the hot financial topics among researchers and scholars. Its importance comes from the fact that capital structure is closely related to companies' ability to meet different stakeholders' needs. A suitable capital structure will boost the business and create a competitive advantage in the context of fierce competition. Many companies choose an optimal debt level based on the trade-off between interest and debt costs. This study aimed to test the existence of trade-off theory in capital structure, the case of Vietnam's real estate companies, which are growing very fast recently. Instead of considering constant optimal leverage to test the trade-off model, we take advantage of the dynamic capital structure determined by growth opportunities, profitability, tax incentives, tangibility, liquidity, and firm size. The dynamic panel data regression was estimated by the system Generalized Method of Moment (Sys-GMM). The empirical evidence showed that real estate companies listed in the Vietnamese stock market might change their leverage toward a target capital structure determined by influential factors in a long-term perspective. In particular, the debt-to-asset ratio will change by approximately 14 percent, positively, in response to the difference between the current debt-to-asset ratio and the dynamic target debt-to-asset ratio.

• The Journal of the Acoustical Society of Korea
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• v.19 no.5
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• pp.79-83
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• 2000

When passband ripple α/sub p/ and stopband attenuation α/sub s/ at the w/sub s/ where the stopband begins are specified in filter design, △α/sub s/ usually exceeds the specification by △α/sub s/ due to the necessity that the order n of the filter function be an integer. In this paper, we apply a trade-off method to remove the excess stopband attenuation △α/sub s/ for reducing the value of pole-Q and improving the characteristics of the Chebyshev filter function. We also apply the trade-off method of pole-Q reduction to the modified Chebyshev function, and then the 4 types of function have been analyzed to compare in frequency and time domain characteristics. The trade-off method reduces the pole-Q which influences the filter characteristics to maximum 49.6% without increase of the order n. Thus implies that they have the improved characteristics such as the reduced passband ripple and flatter delay characteristics as compared Chebyshev filter function before trade-off. And the unit step response shows shorter delay time and settling time in time domain performance.

• Journal of Aerospace System Engineering
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• v.10 no.3
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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 the Korea Institute of Military Science and Technology
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• v.3 no.1
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• pp.66-75
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• 2000

The purpose of this study is to develop and illustrate methods of applying trade-off techniques to landing craft air cushion design evaluation. The problem areas of concern are the application of quantitative analytical methods to conceptual design. The interrelationships between composite system measures and selected performance requirements(speed, cruising range, cargo etc.) are analyzed and the expressions for gross weight are developed as functions of performance parameters. Trade-offs of performance parameters in terms of weight are then calculated. The application of these results to evaluation of Require Operational Capabilities are illustrated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.40-41
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• 2020

As the capacity of the 3d scanner developed, the reverse engineering using the 3d scanner is emphasized in the construction industry to obtain the 3d geometric representation of buildings. However, big size of the indoor point cloud data acquired by the 3d scanner restricts the efficient process in the reverse engineering. In order to solve this inefficiency, several pre-processing methods simplifying and denoising the raw point cloud data by the rough standard are developed, but these non-standard methods can cause the inaccurate recognition and removal the key-points. This paper analyzes the correlation between the accuracy of wall recognition and the density of the data, thus proposes the proper method for the raw point cloud data. The result of this study could improve the efficiency of the data processing phase in the reverse engineering for indoor point cloud data.

• Journal of the Korean housing association
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• v.1 no.2
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• pp.49-66
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• 1990

This study is a case study to grasp residents` trade-off preference and opinions for selected interior environmental attributes of muilti-family housing. Interiew with structured questionnaire was carried out through pilot and main survey. On the basis of the result of pilot survey, interior environmental attributes for the main survey were selected. Selected attributes were the size of each residential room, the degree of openness between two rooms and interior facilities. Among them, trade-off approach was applied to the size of each residential room and interior facilities. For the main survey. 45 housewives living in 31 pyung apartment of a selected construction company to grasp the residents` trade-off preference and opinions on the selected attributes. In terms of the size of each room, subjects wanted the room to be lager, whereas master bedroom smaller, and family bathroom larger, wheareas toilet near master bedroom smaller. In terms of the degree of openness between two rooms, the present degree of openness between private and service area such as living room and balcony, and second bedroom and adjacent balcony need to be more open, whereas the present degree of openness between living room and dining room and between living room and kitchen need to be more closed. The comparative orders of important intems were the ventilation facility in the bathroom, drying poles for clothes in the balcony, interior landscape, and workable for hand washing clothes. In conclusion, measurement of preference using trade-off approach about selected interior environmental attributes in post-occupancy evaluation was regarded as a promising evaluation method to grasp the practical and comparative preference under constraints comparing to the typical existing methods.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.21 no.1
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• pp.31-40
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• 2018

Since the Millennium Ecosystem Assessment Report was published in 2005, the conflict between development and the preservation of the ecological environment has turned to paying attention to value assessments in rational decision-making. In recent years, the concept of ecosystem services has been recognized as a viable one for making significant decisions. However, a trade-off between increase and decrease occurs between the ecosystem services sub-categories (cultural service, regulating service, supporting service, and provisioning service), for which research centering on target sites is needed. To this end, the present study aims to investigate the trade-off relationship between service categories to search for reasonable decision-making strategies. As the research method, a survey was conducted using the translated version of SoIVES(Social Value for Ecosystem Services) 3.0 questionnaire of the United States Geological Survey. The research findings demonstrate the economic value, based on the derived monetary value of each service category, the economic value of the target site was compared among landscape aesthetic value 8,050,000 won, recreation value 6,750,000 won, biodiversity value 4,610,000 won, healing value 3,970,000 won, life-sustaining value 2,090,000 won, and productive value 220,000 won. And then the primarily recognized value criteria of the Tancheon ecosystem services illustrate landscape aesthetic and recreation value. Besides, this study illustrates visualized trade-off relationships based on user perception, and the derived relations illustrate the trade-off relationship between the cultural service, regulating service, supporting service, and provisioning service, as well as relationships between the components of the sub-categories.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.27 no.1
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• pp.45-54
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• 2024

This study developed a model to evaluate the co-benefits and trade-off effects between biodiversity and carbon storage capacity based on the implementation locations of nature-based solutions. The model aims to propose optimal implementation locations by using the conceptual idea of edge effects for carbon storage and connectivity for biodiversity. The co-benefits were considered by simultaneously taking into account two effects rather than a single effect. Trade-off effects were observed among optimal plans through a comparison of benefits. The NSGA-II multi-objective optimization algorithm was utilized, confirming the identification of Pareto-optimal solutions. The implementation patterns of Pareto-optimal solutions for green areas were examined. This study holds significance in proposing optimal locations by evaluating various co-benefits and trade-off effects of nature-based solutions. By advancing models based on this evaluation framework, it is anticipated that the assessment of co-benefits and trade-off effects among various benefits of nature-based solutions, such as climate change mitigation, enhancement of biodiversity, and provision of ecosystem services, can be accomplished.