• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.37-51
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• 2021

The pressure drop phenomenon that occurs when the same flow rate is supplied to the gas regulator was analyzed. The regulator moves the position of the piston through the interaction of the force acting on the upper and lower parts of the piston and the spring tension to release the pressure of a specific range in a specific environment as constant pressure, thereby maintaining the pressure. The flow characteristics and pressure control process of the regulator were investigated through a numerical analysis technique as the volume of the fluid inside the regulator changed. As the gap between the piston and the piston seat decreased, the pressure drop increased and the flow velocity increased. It was verified through numerical analysis that the piston was positioned at 0.12mm under the same conditions as the pressure-flow test (inlet pressure 3MPa, outlet pressure 0.8MPa, flow rate 70kg/h).

• Journal of Korean Philosophical Society
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• v.146
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• pp.193-217
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• 2018

Following the lead of Isaiah Berlin, many liberals favor a negative conception of liberty because it limits the amount of interference and coercion that the state has in individual's lives. Such moves leave individuals to place value on their life choices or step back and revise them if desired. It is one thing, however, to argue that modern republicanism characterized by liberty as non-domination contains an alternative conception of liberty.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1690-1698
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• 2018

Recent advances in ICT technology have transformed many of our daily lives and attracted a lot of attention to personal health. Heart beat measurement that reflects cardiac activities has been used in various fields such as exercise evaluation and psychological state evaluation for a long time, but its utilization method is limited due to its differentiation from clinical electrocardiogram. Therefore, in this study, we could observe the change of the measured signal according to the change of the distance and the position of the measuring electrodes which are non-standard electrode configuration. Based on the electric dipole model of the heart, correlation with clinical electrocardiogram could be confirmed by synthesizing multiple surface potentials measured with a shorter electrode distance than standard one. From the electromagnetic point of view, the distance between the measuring electrodes corresponds to the distance that the electric potential by the cardiac electric dipole moves, and the electric potential measured at the body surface is proportional to the moving distance of the electric potential. Therefore, it is preferable to make the distance between electrodes as long as possible, and to position the measuring electrode close to the ventricle rather than the atrium. In addition, it was found that standard electrocardiographic waveforms could be synthesized by using arithmetic sum of multiple measuring electrodes due to the relationship of electrical dipole vectors, which is obtained by dividing and positioning a plurality of measuring electrodes on a reference electrode line, such as Lead-I, Lead-II direction. Also, we obtained a significant Pearson correlation coefficient ($r=0.9113{\pm}0.0169$) as a result of synthetic experiments on four subjects.

• Journal of the Korean GEO-environmental Society
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• v.20 no.8
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• pp.5-12
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• 2019

A pile group, that consists of several piles connected by a pile cap, is used as the superstructure. The pile supports vertical and horizontal load to design the pile group, but the effect of bearing capacity of the pile cap has not considered. Various researches have been conducted to reflect the effect of bearing capacity of the pile cap in order to reduce the amount of piles in the range of the stability under the vertical load of the superstructure. However, the effect of bearing capacity under the horizontal seismic load has not been studied adequately. Therefore, a shaking table test was carried out with different-sized pile caps that support the superstructure in this study. This test was to verify the influence of the size of the pile cap in the group pile under the horizontal load. The result shows that the size of the pile cap affects to the dynamic behavior of the superstructure and the pile group. Also, the bigger size of the pile group makes the larger constraint effect of ground, and it results that both the ground and the pile moves as a whole.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.114-121
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• 2019

Tailless aircraft have advantages of low visibility compared to conventional aircraft, but drawback of poor stability as well which makes designing controller difficult. The controller design is more difficult, especially when the center of gravity moves due to store release or fuel consumption during flight. In this paper, an L1 adaptive controller is proposed as a way to overcome these problems. The reliability and performance of the controllers were verified by non-linear simulations. RPV Flying Quality Design criteria were used for design criteria. Using the simulation, it is shown that the adaptive controller maintains stability of the unmanned aircraft for sudden large change in the inertial properties. It is also shown that the calculation burden can be reduced when it is used with the gain scheduling method.

• Human Ecology Research
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• v.57 no.1
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• pp.27-40
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• 2019

Based on the stress process model, this study examined the process of how military personnel's occupational characteristics (i.e., long and unspecified work hours, frequent moving) is associated with their wives' marital satisfaction and parenting stress. We focused on whether the wives' perception toward the characteristics of military occupation and the wives' military family pride mediated the association. An online survey was conducted with 323 women married to professional active-duty military husbands, had at least one preschool child, and lived with the husband and child. Using structural equation modeling, we found that the wives' perception of military occupational characteristics and military family pride mediated the relationship between their husband's work hours and the wives' marital satisfaction and parenting stress. This serial multiple mediation indicated that the longer and more unspecified the husband's work hours were, the more negative the wife's perceptions were towards his military occupation, which led to lower marital satisfaction and higher parenting stress. The single mediation effect of negative perceptions was also significant. Frequent moving was indirectly related to the wives' marital satisfaction and parenting stress through only the wives' negative perceptions toward military occupational characteristics. This result indicates that military spouses who experienced frequent moves are likely to have more negative attitudes toward military occupation, which leads to lower marital satisfactions and higher parenting stress. This study contributes to the literature by identifying the underlying mechanisms between military occupational characteristics and military wives' family life through the mediating roles of negative perceptions and military family pride.

• Membrane Journal
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• v.29 no.1
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• pp.37-43
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• 2019

In this study, we investigated how the force-field, which is the most important factor to define atomic motion in molecular dynamics (MD), affects the motion of the polymer and gas molecules. The repeat units and the polymer structure were well simulated in all five force-fields, and the distribution of the polymer linear chain in the final polymer 3D model did not show any significant difference. However, the movement of actual gas molecules showed a very different tendency, which was also observed in COMPASS and pcff using the same functional form. Therefore, even if the same structure is used, it can be seen that the motion of the gas molecule moves under the influence of the force-field continuously over time, so that the effect is much larger than that of macromolecules such as a polymer linear chain. Accordingly, in case of using different force-fields, it is necessary to be very careful in comparison of those results.

• The Journal of Society for e-Business Studies
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• v.23 no.3
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• pp.225-237
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• 2018

The demand for processing large data streams is growing rapidly as the generation and processing of large volumes of data become more popular. A variety of large data processing technologies are being developed to suit the increasing demand. One of the technologies that researchers have particularly observed is the data stream clustering with sliding windows. Data stream clustering with sliding windows may create a new set of clusters whenever the window moves. Previous data stream clustering techniques with sliding windows exploit the coresets, also known as group features that summarize the data. In this paper, we present some reformable elements of a group-feature based algorithm, and propose our algorithm that modified the clustering algorithm of the original one. We conduct a performance comparison between two algorithms by using different parameter values. Finally, we provide some guideline for the selective use of those algorithms with regard to the parameter values and their impacts on the performance.

• Journal of the Korea Society of Computer and Information
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• v.24 no.3
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• pp.181-190
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• 2019

Today, in the information society, since the government administration of all countries places importance on clarity and efficiency, the authority concentration of the administration is inevitable. Therefore, the Parliament, which is a legislative body, is at a time when the policy control function to check and monitor it is becoming more important. In particular, due to the emergence of parliamentary democracy, in the reality that the people must elect representatives and represent their own opinions, the parliamentary inspection system is very valuable in that it satisfies the right of the people to know and ultimately enables the people to democratically control the administration. The role of the Parliament moves from the inherent legislative function to the information collection and disclosure of government administration, discussion and resolution of political issues, and observation and supervision of the administration. And it can be seen as the global trend. As a result of this trend, status and role of the National Assembly is being strengthened from the legislative body to the control agency of government administration. Thus, the most substantive authority of Article 61 of the Constitution can be deemed the parliamentary inspection system. The parliamentary inspection system is a system that let exercise the legislation, budget, and authority to control of state administration by identify the challenges and policy implementation of each country's institutions through the audit of the executive administration's overall government administration performance outside the National Assembly. However, due to the amendment of Constitution in 1988, the parliamentary inspection right and investigation of state administration right had reinstated and the parliamentary inspection system, which is being implemented annually, is the 31st year of the year in 2019. However, the general evaluation of the public is negative and insufficient time for inspections, lack of sanctions on nonattendance witnesses, excessive data submission, and refusal to submit materials by the administration were pointed out as the problem. Therefore, in this paper, the researcher tries to point out the overall problems of the parliamentary inspection system and to summarize the effective improvement plans.

• Geomechanics and Engineering
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• v.16 no.6
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• pp.589-597
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• 2018

Centrifuge model tests were used to simulate pile-raft composite foundation and pile-geogrid composite foundation with different pile spacing for researching the time effect of negative skin friction of rigid piles in high-speed railways. The research results show that the negative skin friction has a significant impact on the bearing capacity of composite foundation. Pile-raft composite foundation has higher bearing capacity compared to pile-geogrid composite foundation to reduce the effect of negative skin friction on piles. Both the foundation settlement and negative skin friction have significant time effect. The distribution of skin friction can be simplified as a triangle along the pile. The neutral point position moves deeper in the postconstruction stage at larger pile spacing. For pile-geogrid composite foundation, the setting of pile-cap affects the position of neutral point in the post-construction stage. Reinforced cushion with geotextile may promote the better performance of cushion for transmitting the loads to piles and surrounding soils. Arching effect in the cushion of the composite foundation is a progressive process. The compression of the rigid piles contributes less than 20% to 25% of the total settlement while the penetration of the piles and the compression of the bearing stratum below the pile tips contribute more than 70% of the total settlement. Some effective measures to reduce the settlement of soils need to be taken into consideration to improve the bearing capacity of pile foundation.