• Elastomers and Composites
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• v.20 no.2
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• pp.115-131
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• 1985

Heavy residual fuel oils is a mixture of reduced crude from crude unit, bottom products from vacuum and/or catalytic cracking unit with distillate to meet the specification and generally used as heavy fuel oil for large combustion engines, boilers, etc$\cdots$. But this study was made to investigate heavy residual fuel oils for using as industrial raw material and resulted the following possiblities as valuable raw material as well as heavy fuel oil. 1) Production of straight asphalt through vacuum distillation unit. 2) Using straight asphalt from vacuum distillation unit for manufacturing of blown asphalts, cut back asphalts, emulsified asphalts and asphalt compound, rubber/asphalt sheet, etc$\cdots$. 3) Using waxy oil side streams for manufacturing of raw oil to be lube oil base stocks through solvent dewaxing. 4) Production of lube base oils and rubber process oils from dewaxed raw oil through chemical treatments. 5) Manufacturing of paraffine wax from slack wax to be produced as by product of dewaxing process.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.2
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• pp.257-265
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• 2011

As the competitive market system has been introduced to the electrical power trade, the priority concern would be that the price of electrical power should be reasonable. It is because, when this rule is solid, we can avoid the distortion of competition and assure the greater efficiency in management. LMP(Locational Marginal Price) means marginal price at each bus. This components consist of energy, loss and congestion cost. At this point, the LMP result that is calculated by traditional model is changeable by the location of the slack and can not be used in bilateral Transaction. This paper proposed algorithm is proved its rationality and credibility by comparing the result of the simulation of virtual 6_bus system that is calculated by traditional method, and showed that the LMP components are changed according to the Transaction Strategy. Furthermore, It shows the effect of additional congestion cost on the transmission line that has bottle neck frequently by simulation.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.797-799
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• 1996

This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these equations become one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack bus or generator bus, which is specified voltage magnitude, it becomes One equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, solutions are obtained with simple computation. Solutions obtained are used for evaluating of voltage stability through sensitivity analysis. Also, considering of reactive power source, method for evaluating the voltage stability is introduced. The proposed method was validated to 2-bus and IEEE 6-bus system.

• Journal of the Korean Society of Clothing and Textiles
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• v.6 no.2
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• pp.9-15
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• 1982

This study was conducted to examine the relation between the clothing materials and the garment's ease under wearing condition. Wearing test of slacks in the same pattern which were made of 3 woven fabrics and 1 knitted fabric have teen carried out. Subjects were 5 female students. Some physical properties of these fabrics were investigated. The following results were obtained. 1, By analysis variance with the results of sensory test which was tested by paired com-parison method, it was obtained that the effect of materials on the garment's ease were significant at the $1\%$ level on every part of stacks and posture of subject. It indicates that there is a difference of materials from materials in garment's ease. 2. Significant at the $5\%$ level among the materials. Jersey and Jean were looser than the other two materials. Clothing materials have considerable effect on the garment's ease of slacks, therefore it was noticed that the ease of slacks must have considered the clothing materials. It is more necessary in working dress. 3. Elastic recovery of width was more contributive to garment's ease of slacks than any other physical properties.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.1
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• pp.70-77
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• 2013

The theory of two-dimensional quality, in particular, the Kano model that is developed by the analogy with the M-H theory, has been applied in various industry fields for more than three decades. Importance-Performance Analysis (IPA) assumes that the degree of physical fulfilment of quality attributes and the satisfaction of that attribute is linear, and therefore, it is applicable to the traditional one-dimensional attribute, not other quality types defined in the Kano's model such as attractive or must-be attribute. To solve this problem, the current study suggests a new importance-satisfaction analysis using a modified IPA in accordance with the three quality types and a diagonal method introduced by Slack (1999) to determine improvement priority. For this, I investigated 19 smartphone's quality attributes and conducted a survey of 334 university students for the results of Kano's model, which adopted from Song and Park (2012)'s study, and the importance/satisfaction of the quality attributes and the results of the priority for improvement of the 19 quality attributes. The results show that the proposed I-S priority model is better than the conventional IPA based on the comparison results of determination coefficient from the regression analysis of the two models.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.2
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• pp.55-61
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• 2011

We propose power-saving real-time scheduling method for mixed task sets which consist of both time-based periodic and event-based aperiodic tasks in the automotive operating system. In this system, we have to pursue maximization of power-saving using the slack time estimation and minimization of response time of aperiodic tasks simultaneously. However, since these two goals conflict each other, one has to make a compromise between them according to the given application domain. In this paper, we find the adjustment factor which gives better response time of aperiodic tasks with slight power consumption increase. The adjustment factor denotes the gravity of response time for aperiodic tasks. We apply the ccEDF scheduling for time-based periodic tasks and then calculate new utilization to be applied to the adjustment factor. In this paper, we suggest the lccEDF algorithm to make a tradeoff between the two goals by systematically adjusting the factor. Simulation results show that our approach is excellent for variety of task sets.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.419-425
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• 2020

DC distribution system has been evaluated as an excellent one in comparison with existing AC distribution network because it needs fewer power conversion stages and the full capacity of the equipment can be used without consideration for power factor. Recently, research and development on the implementation of DC distribution networks have been progressed globally based on the rapid advancement in power-electronics technology, and the technological developments from the viewpoint of infrastructure are also in progress. However, to configure a distribution network which is a distribution line for DC, more accurate and rapid introduction of analysis technology is needed for the monitoring, control and operation of the system, which ensure the system run flexible and efficiently. However, in case of a bipolar DC distribution network, there are two buses acting as slack buses, so the Jacobian matrix cannot be configured. Without solving this problem, DC distribution network cannot be operated when the network is unbalanced. Therefore, this paper presented a comprehensive method of analysis with consideration of operating elements which are directly connected between neutral electric potential caused by the unbalanced of load in DC distribution network with bipolar structure.

• Journal of Ocean Engineering and Technology
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• v.33 no.1
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• pp.42-49
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• 2019

Drilling mud was used once in the step of separating the gas and powder they were transported to a surge tank. At that time, the fine powder, such as dust that is not separated from the gas, is included in the gas that was separated from the mud. The fine particles of the powder are collected to increase the density of the powder and prevent air pollution. To remove particles from air or another gas, a cyclone-type separator generally can be used with the principles of vortex separation without using a filter system. In this study, we conducted numerical simulations of air-particle flow consisting of two components in a cyclone separator in a mud handling system to investigate the characteristics of turbulent vortical flow and to evaluate the collection efficiency using the commercial software, STAR-CCM+. First, the single-phase air flow was simulated and validated through the comparison with experiments (Boysan et al., 1983) and other CFD simulation results (Slack et al., 2000). Then, based on one-way coupling simulation for air and powder particles, the multi-phase flow was simulated, and the collection efficiency for various sizes of particles was compared with the experimental and theoretical results.

• Journal of Navigation and Port Research
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• v.46 no.2
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• pp.134-144
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• 2022

The development and operation of autonomous ships are spotlighted as a next-generation technology that will provide newbenefits for the maritime business during the fourth industrial revolution. To expand the adoption of autonomous ships, the much more interest of the nation and the industries will have to be changed to actual adoption in shipping companies. For this, it is judged that research to identify the factors impacting the adoption intention of autonomous ships should be preceded. However, most studies on autonomous ships have focused on developing the technology, revising the law, establishing policies, and managing human resources, with few studies on influencing factors in the adoption of autonomous ships. A model, to identify the factors that impact the intention to the adoption of autonomous ships, based on the theory of diffusion of innovation and the TOE framework was developed. The suggested model was verified through empirical analysis targeting the shipping companies and the marine industries in Korea. As the result of this study, it was found that top management support, financial slack, and competitive intensity significantly impacted the intention to adopt autonomous ships. Additionally, it was revealed that the overall awareness of autonomous ships among Korean shipping companies is poor.

• Steel and Composite Structures
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• v.49 no.2
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• pp.125-141
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• 2023

Firstly, a new kind of prismatic tensegrity structures with redundant cables is defined, the topology, geometry and forming conditions of which are introduced further. The development of its mechanical properties including self-stress states and structural stiffness with the increment of the twist angle is also investigated carefully. Combined with the topology of this kind of structures, a reasonable erection scheme is proposed, in which some temporary lifting points need to be set and two groups of vertical cables are tensioned in batches. Then, a simplified dynamic relaxation method is employed to track the erection process inversely, which aims to predict each intermediate equilibrium state during the construction, and give the key structural parameters that can effectively guide the construction. The removal of the active cables, the relaxation or tension of the passive cables are simulated by controlling their axial stiffness, so that the structural composition as well as the serial numbers of the elements always keep invariant regardless of the withdrawal of the slack cables. The whole analysis process is clear in concept, simple to implement and easy to popularize. Finally, several examples are given to verify the practicability and effectiveness of the proposed method further.