• Journal of Communications and Networks
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• v.13 no.6
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• pp.602-611
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• 2011

The inter-domain routing scalability issue is a major challenge facing the Internet. Recent wide deployments of multihoming and traffic engineering urge for solutions to this issue. So far, tunnel-based proposals and compact routing schemes have been suggested. An implicit assumption in the routing community is that structured address labels are crucial for routing scalability. This paper first systematically examines the properties of identifiers and address labels and their functional differences. It develops a simple Internet routing model and shows that a binary relation T defined on the address label set A determines the cardinality of the compact label set L. Furthermore, it is shown that routing schemes based on flat address labels are not scalable. This implies that routing scalability and routing stability are inherently related and must be considered together when a routing scheme is evaluated. Furthermore, a metric is defined to measure the efficiency of the address label coding. Simulations show that given a 3000-autonomous system (AS) topology, the required length of address labels in compact routing schemes is only 9.12 bits while the required length is 10.64 bits for the Internet protocol (IP) upper bound case. Simulations also show that the ${\alpha}$ values of the compact routing and IP routing schemes are 0.80 and 0.95, respectively, for a 3000-AS topology. This indicates that a compact routing scheme with necessary routing stability is desirable. It is also seen that using provider allocated IP addresses in multihomed stub ASs does not significantly reduce the global routing size of an IP routing system.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.9-14
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• 2014

Self-piercing riveting(SPR) is a mechanical fastening technique which is put pressure on the rivet for joining the sheets. Unlike a spot welding, SPR joining does not make the harmful gas and $CO_2$ and needs less energy consumption. In this study, static and fatigue tests were conducted using tensile-shear specimens with Al-5052 plates for evaluation of fatigue strength of the SPR joints. During SPR joining process for the specimen, using the current sheet thickness and a rivet, the optimal applied punching force was found to be 21 kN. And, the maximum static strength of the specimen produced at the optimal punching force was 3430 N. During the fatigue tests for the specimens, interface failure mode occurred on the top substrate close to the rivet head in the most high-loading range region, but on the bottom substrate close to the rivet tail in the low -loading range region. There was a relationship between applied load amplitude $P_{amp}$ and lifetime of cycle N for the tensile-shear, $P_{amp}=3395.5{\times}N^{-0.078}$. Using the stress-strain curve of the Al-5052 from tensile test, the simulations for fatigue specimens have been carried out using the implicit finite element code ABAQUS. The relation between von-Mises equivalent stress amplitude and number of cycles was found to be ${\sigma}_{eq}=514.7{\times}N^{-0.033}$.

• Journal of Science and Technology Studies
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• v.2 no.1 s.3
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• pp.157-189
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• 2002

Science and technology policy a lot of implicit usjustified assumptions. These assumption without being reflected may cause various social problems. In this paper, lit is shown that philosophy of science could make contribution to resolving these problems. In epistemological viewpoints, theory of science and technology policy has been analyzed. I argue that social kinds, social entities appeared in social science should be interpreted realisticaly. Realizing this realistic interpretation of social kinds, as one field of social sciences, theory of science and technology policy can deal with the causal relation among social entities and the causal influence of science and technology policy more objectively- scientific knowledge has two components. One belongs to coded knowledge and the other belong to tacit knowledge which cannot be coded. I analyze the content and characters of tacit knowledge appeling to Michael Polany. One of the important function of science and technology policy is to make tacit knowledge more fruitful. I argue that philosophy of science fit well this function. Finally I claim that philosophy of science can help science and technology policy to reduce the ethical problems caused by science and technology.

• Smart Media Journal
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• v.10 no.4
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• pp.102-110
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• 2021

Currently, the advanced construction technology endorsement system is being operated to promote the development of domestic construction technology. We tried to examine the implicit meanings inherent in advanced construction technologies by analyzing the relationship between emerging vocabularies with high importance in relation to the advanced construction technologies endorsed through this system. For this purpose, 918 cases of advanced construction technology information were collected. Based on the endorsed year and summary of the advanced construction technologies, the importance of the emerging vocabularies was measured for each advanced construction technology. And, based on the LDA model, the degree of influence between related vocabularies was evaluated for each of the four topic areas. Topics according to the technical application fields were analyzed. From 1990 to 2021, the trend of changes in highly influential vocabularies by each topic was inferred. In the future, changes in the degree of influence of the topics of environment, machinery, facilities, and maintenance and reinforcement of structures and related technology fields were predicted.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.147-156
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• 2011

Since the urbanization process has been taking place, negative outcomes such as environmental pollution and traffic congestion have produced as well. Reflecting the phenomenon, our study assumed that physical structure of urban form were implicit in relation to both economic performance and cost. It can be interpreted that as the urban space has been growing bigger, economic performances such as regional product output, economy of scale and the effect of agglomeration economies are increased. On the contrary, the negative effects such as environmental pollution and traffic congestion were incurred as economic loss and expenses. It means that even though economic performance can help increase regional product output, we should consider the loss on economic expenses which are paid for social problems such as environmental pollution and traffic congestion, which are caused by urbanization. Therefore, this study aims to statistically validate the relationship between traffic congestion as the most representative economy costs and physical characteristics of urban in a large city such as Seoul and to suggest its implications. As a result of model development for empirical analysis, GRDP(0.604), the population(0.582), employment GINI coefficients(0.296), population GINI coefficients(0.254) in order led to congestion cost. We can come to the conclusion that in case of scale factor such as the population, if the population tends to concentrate, urban becomes more crowded and that if GINI coefficients (the population, employment) which are variable on inequality according to region have the disparity with surrounding areas, congestion cost is caused a lot on account of movement related with employment. In addition, this phenomenon was caused if both the population and employment were geographically biased on one side.

• Journal of Music and Human Behavior
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• v.17 no.2
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• pp.1-28
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• 2020

This case study aimed to investigate changes in adolescents' awareness of the motivation behind their excessive internet gaming after group music psychotherapy. Five middle school students participated in six 60-minute group sessions over 4 weeks. The group music psychotherapy program was developed to help participants understand their implicit reasons for excessive internet gaming. Verbal responses were obtained from pre-program and post-program interviews and original lyrics created by participants during program were collected for analysis. Obtained data were analyzed in terms of emotional and cognitive aspects in relation to the participants' awareness of the motivation behind their excessive gaming. The results showed that song writing as creative musical process allowed participants to be aware of positive and negative influence of gaming on themselves and express their motivation to change their perception on gaming behavior. Also, the participants reported that the use of musical product for their daily lives could be an effective coping strategy to manage their gaming behaviors and an alternative for gaming. The findings from this study support that group music psychotherapy can be an effective approach to promote awareness of adolescents' motives for excessive internet gaming and to help adolescents better manage their gaming behaviors.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.143-150
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• 2012

A simulation methodology and corresponding program based on it is to be discussed for analyzing the effects of the networking operation of existing DHC system in connection with CHP system on-site. The practical simulation for arbitrary areas with various building compositions is carried out for the analysis of operational features in both systems, and the various aspects of thermal energy grids with connecting operation are highlighted through the detailed assessment of predicted results. The intrinsic operational features of CHP prime movers, gas engine, gas turbine etc., are effectively implemented by realizing the performance data, i.e. actual operation efficiency in the full and part loads range. For the sake of simplicity, a simple mathematical correlation model is proposed for simulating various aspects of change effectively on the existing DHC system side due to the connecting operation, instead of performing cycle simulations separately. The empirical correlations are developed using the hourly based annual operation data for a branch of the Korean District Heating Corporation (KDHC) and are implicit in relation between main operation parameters such as fuel consumption by use, heat and power production. In the simulation, a variety of system configurations are able to be considered according to any combination of the probable CHP prime-movers, absorption or turbo type cooling chillers of every kind and capacity. From the analysis of the thermal network operation simulations, it is found that the newly proposed methodology of mathematical correlation for modelling of the existing DHC system functions effectively in reflecting the operational variations due to thermal energy grids with connecting operation. The effects of intrinsic features of CHP prime-movers, e.g. the different ratio of heat and power production, various combinations of different types of chillers (i.e. absorption and turbo types) on the overall system operation are discussed in detail with the consideration of operation schemes and corresponding simulation algorithms.