• Environmental and Resource Economics Review
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• v.23 no.3
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• pp.435-451
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• 2014

This paper attempts to evaluate an environmental regulation program which enforces installation of filtering equipment to reduce major air pollutants from used diesel vehicles. A real option model is presented to incorporate fuel cost uncertainty and irreversibility of emission-reducing investment. A finite-life option based on finite difference method is developed to consider the limited life expectancy of used vehicles. After taking into account social benefits from emission reduction and costs from decreasing fuel efficiency after the adoption of filtering technology, the result finds overall positive performance of the Pollution Reduction Program. However, the result suggests that the Program be designed to be more specific to vehicle types to improve program performance.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.62-70
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• 2013

As the aviation industry looks to the future, fuel saving and $CO_2$ emission reduction play a dominant role in meeting the business challenges presented by global financial uncertainty. The IATA and International Government effort to save fuels, and then save 4 billion gallons of fuel burned, while reducing $CO_2$ emissions by 34 million tons. The various reduction methods adapted airlines and airports. We focused on optimized flight operation procedures for saving fuel and reduction emission cases. IATA and Canada government research reports focused on four methods that Engine Core Washing, Portable Water Management, Single Engine Taxi, APU limit operation. Apply to domestic airlines fuel data, Engine Core washing was saving more than Twenty-four thousand tons $CO_2$ emissions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.107-113
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• 2014

The derivation of optimal information from decision table is based on the concept of indiscernibility relation and approximation space in rough set. Because decision table is more likely to be susceptible to the superposition or inconsistency in decision table, the reduction of attributes is a important concept in knowledge representation. While complete subsets of the attribute's domain is considered in algebraic definition, incomplete subsets of the attribute's domain is considered in information-theoretic definition. Therefore there is a marked difference between algebraic and information-theoretic definition. This paper proposes a conditional entropy using rough set as information theoretical measures in order to deduct the optimal information which may contain condition attributes and decision attribute of information system and shows its effectiveness.

• Culinary science and hospitality research
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• v.14 no.4
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• pp.339-356
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• 2008

The purpose of this study is to provide the developmental basic data of a change in shift work types by making a self-administered survey of the effect of commitment by shift work and the open kitchen system on job satisfaction and job stress, and mutual relation between variables on 287 cooks in luxury hotels. Analysis showed that the operation of the shift work system was effective in reducing the internal stress of the cooks, their external stress, or their self-uncertainty on the job, and the business by the open kitchen system was effective in raising self-esteem. In addition, job commitment by shift work and the open kitchen system were effective in promoting the job satisfaction of employees, interpersonal relations, promotion, benefits and wages. Consequently, the decrease of external and internal stress or self-uncertainty and the improvement of job satisfaction can be connected with the increase of productivity or cost reduction. Therefore, the open kitchen system should be properly applied to the shift work system, along with sanitation, safety and the periodic checkup of kitchen.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.3-6
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• 2007

Korea Aerospce Research Institute(KARI) has been developing the first civilian rocket, Korea space launch vehicle (KSLV-I), which can put the small size satellite into designated orbit. Developing launch vehicles contains a lot of uncertainty due to large scale, complexity, and technical difficulty. The uncertainty may become risk in the areas of business and technology which causes schedule delay, cost increase, and design changes of subsystems and components. This study describes the technical risk identification methods using FTA and procedures of planning and implementation of risk assessment and reduction of launch vehicle propulsion system.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.529-534
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• 2008

Interzonal air movements are important to characterize overall ventilation performance of complicated multi-zone buildings. Tracer gas techniques are widely used to measure ventilation rates, ventilation effectiveness, and interzonal air movements. Depending on the number of gases used, they are divided into single and multi tracer gas methods. This paper deals with the comparison of the tracer gas methods in measuring air exchange rate between rooms. Experiments have been conducted in a simple two-room model with known airflow rates. In multi-gas procedure, the concentration decays of two tracer gases, i.e SF6 and R134a are measured after simultaneous injections in each room. The single tracer gas method is also applied by injecting SF6 gas with a time lag between two rooms. The data reduction procedures are developed to obtain the interzonal airflow rate using the matrix inversion, and various data manipulation methods are tested, such as data shift, interpolation, and smoothing. Uncertainty for each airflow rate is investigated depending on the parameters based on the setting values.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.4
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• pp.181-186
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• 2013

The construction costs for nonstructural systems such as mechanical/electrical equipment, ceiling system, and piping system occupy a significant proportion of the total cost. These nonstructural systems can also cause considerable economic losses and loss of life during and after an earthquake. Therefore, reduction of seismic risk of nonstructural components has been emerging as a key aspect of research in recent year. The primary objective of this study was to evaluate the seismic performance of a single-story and multi-story piping system installed in low-rise building and to identify the seismic vulnerability of the current piping systems. The seismic performance evaluation of the piping systems was conducted with 5 different earthquakes to account for the ground motion uncertainty and the preliminary results demonstrated that the maximum displacements of each floor in the multi-story piping system increased linearly with increasing floor level in the building system. This study revealed that the current design piping systems are significantly sensitive to the effect of floor height, which stress the necessity to improve the seismic performance of the current piping systems by, for example, strengthening with seismic sway bracing using transverse/longitudinal bracing cables or hangers.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.655-667
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• 2018

To evaluate the stability of a rock slope with one pre-exiting vertical crack, this paper performs corresponding probabilistic stability analysis. The existence of cracks is generally ignored in traditional deterministic stability analysis. However, they are widely found in either cohesive soil or rock slopes. The influence of one pre-exiting vertical crack on a rock slope is considered in this study. The safety factor, which is usually adopted to quantity the stability of slopes, is derived through the deterministic computation based on the strength reduction technique. The generalized Hoek-Brown (HB) failure criterion is adopted to characterize the failure of rock masses. Considering high nonlinearity of the limit state function as using nonlinear HB criterion, the multivariate adaptive regression splines (MARS) is used to accurately approximate the implicit limit state function of a rock slope. Then the MARS is integrated with Monte Carlo simulation to implement reliability analysis, and the influences of distribution types, level of uncertainty, and constants on the probability density functions and failure probability are discussed. It is found that distribution types of random variables have little influence on reliability results. The reliability results are affected by a combination of the uncertainty level and the constants. Finally, a reliability-based design figure is provided to evaluate the safety factor of a slope required for a target failure probability.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.28-31
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• 2003

In the present work, a main purpose is to propose a fuzzy integral-based aggregation framework to complementarily combine partial information due to lack of completeness. Based on Choquet integral (CI) viewed as monotone expectation, we take into account complementary, non-interactive, and substitutive aggregations of different sources of defective information. A CI-based system representing upper, conventional, and lower expectations is designed far handling three aggregation attitudes towards uncertain information. In particular, based on Choquet integrals for belief measure, probability measure, and plausibility measure, CI$\_$bi/-, CI$\_$pr/ and CI$\_$pl/-aggregator are constructed, respectively. To illustrate a validity of proposed aggregation framework, multiple matching systems are developed by combining three simple individual template-matching systems and tested under various image variations. Finally, compared to individual matchers as well as other traditional multiple matchers in terms of an accuracy rate, it is shown that a proposed CI-aggregator system, {CI$\_$bl/-aggregator, CI$\_$pl/-aggregator, Cl$\_$pl/-aggregator}, is likely to offer a potential framework for either enhancing completeness or for resolving conflict or for reducing uncertainty of partial information.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.97-109
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• 2014

Social media is a general term for online services by which users share opinions, perspectives, and experiences. It supports interactions between users in sharing contents on it and weak ties among them play an important role in the process. This exploratory study attempts to identify crucial factors of establishing weak ties between social media users in the perspective of social network theory and uncertainty reduction theory. We collected data through diary study and in-depth interview and analyzed it following grounded theory approach. As a result, social media users more actively interacted each other or shared contents based on weak ties, compared to strong ties. In addition, similarity, self-disclosure, and relevance appeared to facilitate establishment of weak ties, by reducing psychological distance between social media users and perceived uncertainty of them.