• Proceedings of the KSR Conference
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.612-618
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• 2009

Recently the roles of railways about the prevention of global warming caused by greenhouse gases and for low carbon green growth are larger than ever. And the railroad-related research institutions have been active in researching for energy conservation. Especially the urban railroad has been emerged as the best means of transportation compared to the general public transportation systems in punctuality, stability, ecology and etc. In operating the urban railroad system there are various ways for energy savings. In the larger category, One is the hardware aspect according to the structure of the vehicle and the development of control systems. The other is the software aspect which efficient train operation can be made through control of driving patterns and driving diagram. In this paper, there is sense to analyze the result in verifying expectation relation with variable and the use of electric power on this after selecting main variables that can influence to the energy of the train operation in the software aspect. First, after collecting the basic data related to operation(train speed, operating hours, power consumption, the position of stopping station, electrical power system etc.) and according to this, investigating the consumption of the energy of the operation, in the side of energy consumption deducing and analyzing problem, this will be found solutions.

• Informatization Policy
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• 제23권1호
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• pp.74-93
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• 2016

This paper proposes Korean national science and ICT policies in artificial intelligence (AI) field. After analyzing the AI trends in major countries as an initiative for global competitiveness, we suggest for new solutions for nutcracker threats and provide policy recommendations for strengthening competitiveness and commercialization in AI field of Korea. Korea's AI status was diagnosed in the order of governance, research and development (R&D), technology commercialization, law and legislation, and human resources strategy. In conclusion, it proposes improvement of governance, procession of long term future market initiative R&D, development of AI commercialization platforms, preparation of research friendly law and environment, and the nurturing of practical and converging human resources system.

• Journal of Korea Society of Digital Industry and Information Management
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• 제15권4호
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• pp.51-62
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• 2019

Recently, as the number of Smart Phone users increase, the simple payment system has been able to make payments using only card information such as a registered password without extra authorized certificate authentication or input of card information. In this paper, it will examine and analyze simple payment system provided by IT companies and financial institutions and the simple payment system that operates global online payment system by case view of operational direction. Then with this examination, it will study ways to improve the problems with terms of convenience and stability in terms of users. In this paper, it will analyze the inconvenient problem in using the QR code system that recently introduced and will propose solutions. Also, it will propose suggestions to solve inconvenience that caused by system that supports NFC simple payment terminal in Korea is not universalize by analyze case study on the overseas simple payment system. It will also propose opinions on the matters that customer having responsible for event of a small financial accident related to loss or theft when using the simple payment system. Then it will suggest expected requirements to prepare new security technical countermeasures and solve the conditions of meeting expectation satisfaction of users.

• Journal of Korean Society of Water and Wastewater
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• 제30권5호
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• pp.553-559
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• 2016

There has been increasing global interest in the environmental pollution problems produced by fossil fuel consumption and greenhouse gas emissions. In order to tackle these issues, new renewable energy such as solar, wind, bio gas, fuel cell and pressure retarded osmosis(PRO) have been developed extensively. Among these energy sources, PRO is one of the salinity gradient power generation methods. In PRO, energy is obtained by the osmotic pressure generated from the concentration difference between high and low concentration solutions separated by a semipermeable membrane. The development for high power density PRO membranes is imperative with the purpose of commercialization. This study investigates development of thin film composite PRO membrane and spiral wound module for high power density. Also, the influence of membrane backing layer on power density was identified, and the characteristic factors of PRO membranes was determined. Different backing layers were used to improve power density. As expected, the PRO membrane with more porous backing layer showed higher power density.

• Journal of Astronomy and Space Sciences
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• 제26권1호
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• pp.59-74
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• 2009

Relative navigation system is presented using GPS measurements from a single-channel global positioning system (GPS) simulator. The objective of this study is to provide the real-time inter-satellite relative positions as well as absolute positions for two formation flying satellites in low earth orbit. To improve the navigation performance, the absolute states are estimated using ion-free GRAPHIC (group and phase ionospheric correction) pseudo-ranges and the relative states are determined using double differential carrier-phase data and singled-differential C/A code data based on the extended Kalman filter and the unscented Kalman filter. Furthermore, pseudo-relative dynamic model and modified relative measurement model are developed. This modified EKF method prevents non-linearity of the measurement model from degrading precision by applying linearization about absolute navigation solutions not about the priori estimates. The LAMBDA method also has been used to improve the relative navigation performance by fixing ambiguities to integers for precise relative navigation. The software-based simulation has been performed and the steady state accuracies of 1 m and 6 mm ($1{\sigma}$ of 3-dimensional difference errors) are achieved for the absolute and relative navigation using EKF for a short baseline leader/follower formation. In addition, the navigation performances are compared for the EKF and the UKF for 10 hours simulation, and relative position errors are mm-level for the two filters showing the similar trends.

• Journal of Distribution Science
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• 제18권8호
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• pp.55-64
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• 2020

Purpose: This paper addresses issues that concern business-to-business marketing, namely informational justice in the supply chain or organizations. As previously reported by other studies, there is information asymmetry in organizations. The present study explores and addresses this in the medical industry, aiming to investigate how informational justice relates to information quality or logistics performance in the medical industry. This study also suggests a method for development of informational justice in medicine-related fields. Design, methodology, approach: The hypothesis and model were developed through a review of the literature. To this end, we surveyed 293 valid survey samples collected from occupational pharmacists and used structural equation modelling for analysis. Findings: The results of the empirical analysis of the hypotheses showed that symmetric sharing of information between pharmacists and employees of pharmaceutical companies has a positive effect on the perceived quality. Moreover, the results showed that quality information has a positive impact on logistics performance, whereas informational justice does not. Conclusions, implications: If information and explanations are exchanged fairly, information and logistics performance-as well as operational expenses-will be enhanced. Furthermore, our study has immense implications outside of academic applications since it suggests practical solutions to government and medical industry employees.

• Journal of the Korea Safety Management & Science
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• 제10권4호
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• pp.173-179
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• 2008

The portion of air logistics is getting growing in the global logistics and customer need the rapidity and accuracy for freight delivery. But, the process of air logistics is so complicated because there are too many stakeholders involved in the process. So we suggest the way to make simple the process for improving ability of handling air freights. First, we analyze the AS-IS process and problems by studying previous documents and researching the field. Also we offer how to adopt the ways that are solutions concerning AS-IS process. Second, we suggest integrated information system that will make it simple the air logistics process and mitigate the intensive work load of air cargo. Also we show the reliance about our suggestion by simulation comparing TO-BE process to AS-IS process. We result in that this study will contribute to improve air logistics process by making simple the process.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 한국퍼지및지능시스템학회 2001년도 춘계학술대회 학술발표 논문집
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• pp.65-68
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• 2001

RBFN has some problem that because the basis function isnt orthogonal to each others the number of used basis function goes to big. In this reason, the Wavelet Neural Network which uses the orthogonal basis function in the hidden node appears. In this paper, we propose the composition method of the actual function in hidden layer with the scaling function which can represent the region by which the several wavelet can be represented. In this method, we can decrease the size of the network with the pure several wavelet function. In addition to, when we determine the parameters of the scaling function we can process rough approximation and then the network becomes more stable. The other wavelets can be determined by the global solutions which is suitable for the suggested problem using the genetic algorithm and also, we use the back-propagation algorithm in the learning of the weights. In this step, we approximate the target function with fine tuning level. The complex neural network suggested in this paper is a new structure and important simultaneously in the point of handling the determination problem in the wavelet initialization.

• Geomechanics and Engineering
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• 제5권6호
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• pp.499-517
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• 2013

In order to investigate shear behavior of granular materials due to excavation and associated unloading actions, load-controlled plane strain compression tests under decreasing confining pressure were performed under drained conditions and the results were compared with the conventional plane strain compression tests. Four types of granular material consisting of two quartz sands and two glass beads were used to investigate particle shape effects. It is clarified that macro stress-strain behavior is more easily influenced by stress level and stress path in sands than in glass beads. Development of localized deformation was analyzed using photogrammetry method. It was found that shear bands are generated before peak strength and shear band patterns vary during the whole shearing process. Under the same test condition, shear band thickness in the two sands was smaller than that in one type of glass beads even if the materials have almost the same mean particle size. Shear band thickness also decreased with increase of confining pressure regardless of particle shape or size. Local maximum shear strain inside shear band grew approximately linearly with global axial strain from onset of shear band to the end of softening. The growth rate is found related to shear band thickness. The wider shear band, the relatively lower the growth rate. Finally, observed shear band inclination angles were compared with classical Coulomb and Roscoe solutions and different results were found for sands and glass beads.

• Advances in concrete construction
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• 제4권2호
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• pp.107-121
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• 2016

This concrete is one of the most versatile construction material widely used for almost a century now. It was considered to be very durable material and required a little or no maintenance since long time. The assumption is very true, except when it is subjected to highly aggressive environments. The deterioration of concrete structures day by day due to aggressive environment is compelling engineers to assess the loss in advance so that proper preventive measure can be taken to achieve required durability to concrete structures. The compounds present in cement concrete are attacked by many salt solutions and acids. These chemicals are encountered by almost all concrete structures. The present study has been undertaken to investigate the effect of attack of chlorides and sulphates with varying severity on compressive strength of ground granulated blast furnace slag (GGBFS) concrete after immersion in salt solution for 28 days. The results indicate that the durability of GGBFS concrete increases with the increase in percentage replacement of cement by GGBFS for 20% and then gradually decreases with increases in percentage of GGBFS with cement (as in the study for 40% and 60%). Also there is increase in strength of GGBFS concrete with increase in age. Thus the durability of concrete improves when GGBFS is added as partial replacement of cement. In this study the strength of GGBFS concrete is less affected by chemicals as compared to conventional concrete when exposed to aggressive environment.