• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3935-3949
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• 2017

In this paper, a novel multiple description image coding (MDC) scheme is proposed, which is based on the characteristics of the human visual model. Due to the inherent characteristics of human vision, the human eye can only perceive the change of the specific thresholds, that is, the just noticeable difference (JND) thresholds. Therefore, JND model is applied to improve MDC syetem. This paper calculates the DCT coefficients firstly, and then they are compared with the JND thresholds. The data that is less than the JND thresholds can be neglected, which will improve the coding efficiency. Compared with other existing methods, the experimental results of the proposed method are superior.

• Geomechanics and Engineering
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• v.25 no.2
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• pp.159-170
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• 2021

Particle size of tailings in different areas of dams varies due to sedimentation and separation. Saturated hydraulic conductivity of high-stacked talings materials are seriously affected by void ratio and particle breakage. Conjoined consolidation permeability tests were carried out using a self-developed high-stress permeability and consolidation apparatus. The hydraulic conductivity decreases nonlinearly with the increase of consolidation pressure. The seepage pattern of coarse-particle tailings is channel flow, and the seepage pattern of fine-particle tailings is scattered flow. The change rate of hydraulic conductivity of tailings with different particle sizes under high consolidation pressure tends to be identical. A hydraulic conductivity hysteresis is found in coarse-particle tailings. The hydraulic conductivity hysteresis is more obvious when the water head is lower. A new hydraulic conductivity-void ratio equation was derived by introducing the concept of effective void ratio and breakage index. The equation integrated the hydraulic conductivity equation with different particle sizes over a wide range of consolidation pressures.

• Journal of Climate Change Research
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• v.5 no.3
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• pp.267-275
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• 2014

A key driver for climate change caused by global average temperature rise is greenhouse gas cumulative emissions that stay for long term in the atmosphere. Although at the moment there is no GHG emission, global warming will continue owing to GHG cumulative emission. In this study, scenarios are developed based on two types of optimistic and conservative diffusion goal. There were a total of 6 alternatives scenarios. The objective of this study are to compare scenarios in terms of GHG cumulative emissions and alternative fuels. An object of analysis is the residential buildings and time frame of scenarios is set up by 2030. And this study uses the LEAP model that is a bottom-up energy model. In conclusion, It is important to set specific diffusion pathway for mitigating climate change virtually.

• Journal of Korean Society of Water and Wastewater
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• v.38 no.2
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• pp.61-68
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• 2024

In the context of the Ministry of Environment's 2022 Climate Change Adaptation Plan for Public Institutions, public sewage treatment plants are one of the important targets for climate change response aimed at sustainable water management. In this study, it is applied a modified methodology to four water regeneration centers (public sewage treatment facilities) in charge of sewage treatment in Seoul to analyze the impacts and risks of climate change and discuss priorities for adaptation measures. The results of the study showed that heavy rains, heat waves, and droughts will be the key impacts of climate change, and highlighted the need for measures to mitigate these risks, especially for facility managers.

• Industrial Engineering and Management Systems
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• v.7 no.2
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• pp.160-170
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• 2008

This paper proposes a mathematical model for converting conveyor assembly line to cellular manufacturing in complex production environments. Complex production environments refer to the situations with multi-products, variant demand, different batch sizes and the worker abilities varying with work stations and products respectively. The model proposed in this paper aims to determine (1) how many cells should be formatted; (2) how many workers should be assigned in each cell; (3) and how many workers should be rested in shortened conveyor line when a conveyor assembly line should be converted, in order to optimize system performances which are defined as the total throughput time and total labor power. We refer the model to a new production system. Such model can be used as an evaluation tool in the cases of (i) when a company wants to change its production system (usually a belt conveyor line) to a new one (including cell manufacturing); (ii) when a company wants to evaluate the performance of its converted system. Simulation experiments based on the data collected from the previous documents are used to estimate the marginal impact that each factor change has had on the estimated performance improvement resulting from the conversion.

• Knowledge Management Research
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• v.18 no.4
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• pp.181-211
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• 2017

Despite a growing literature focusing on technological development as a key driving force behind the economic performance of a firm or a nation's industy, we still fall short of a comprehensive understanding of how each of the elements required of technological developent and innovation fits togther and leads to economic progress and industry change. This paper seeks to fill this gap by bringing together some of key insights from the theory and research on the coevolutionary process of technology, organizations, and industry, and on the role of institutions in this process. By combining a diverse array of research streams, we provide a broad suvey of foundational work on the following two questions: (1) how the creation and diffusion of innovation occurs and gives rise to structural reconfigurations of the industry, (2) how organisations and technology coevolve, and (3) what is the role of institutions in this coevolutionary process? Based on this literature survey, we also offer a synthesis that can serve as a ground that allows a more nuanced understanding of the sources, dynamics and impacts of technological development and innovation, and interrelationships among technology, organizations and industry change.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.726-735
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• 2009

In this paper, we proposed a novel conditional access system to reduce the overhead transmission rate for messages which verify the entitlement of subscribers in bandwidth-limited system. We adapted a key update system with the tree structure which had been used for IP multicast to a group hierarchy for the subscriber groups or channel groups. We also analyzed the overhead transmission rate for periodic key update and aperiodic one for change in a subscriber. The numerical evaluations show that the proposed system can significantly reduce the overhead transmission rate for dynamic subscriber change up to several hundred thousands times for various system configuration.

• Journal of the Optical Society of Korea
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• v.20 no.2
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• pp.251-256
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• 2016

The prediction of thermal effects in lithography projection objective plays a significant role in the real-time dynamic compensation of thermal aberrations. For the illuminated lithography projection objective, this paper applies finite element analysis to get the temperature distribution, surface deformation and stress data. To improve the efficiency, a temperature distribution function model is proposed to use for the simulation of thermal aberrations with the help of optical analysis software CODE V. SigFit is approved integrated optomechanical analysis software with the feature of calculating OPD effects due to temperature change, and it is utilized to prove the validation of the temperature distribution function. Results show that the impact of surface deformation and stress is negligible compared with the refractive index change; astigmatisms and 4-foil aberrations dominate in the thermal aberration, about 1.7 λ and 0.45 λ. The system takes about one hour to reach thermal equilibrium and the contrast of the imaging of dense lines get worse as time goes on.

• Journal of the Korea Institute of Building Construction
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• v.12 no.6
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• pp.624-635
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• 2012

Construction projects, including housing, are carried out over long periods of time. According to changes to the construction period, the cost of input materials and wages also changes. Therefore appropriate management is important in order to minimize cost risks caused by fluctuations in prices. In Korea, housing units are usually sold in lots prior to construction completion. Therefore, careful management of input elements such as materials and equipment that are sensitive to price fluctuations is very important. This study deals with how the price fluctuation of materials, labor, and equipment influences the change of housing cost and seeks a way for cost management through identifying key resources sensitive to price fluctuation. As a result, a change to the housing cost index multiplies depending on cost changes of materials and labor together. Labor costs are a major factor on the housing cost index. In addition, certain types of materials and labor input to housing construction greatly influence price fluctuations. Thus, it is found that managing those main cost factors is the key for effective cost management.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.12
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• pp.4987-5014
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• 2015

The bilinear pairing, also known as Weil pairing or Tate pairing, is widely used in cryptography and its properties help to construct cryptographic schemes for different applications in which the security of the transmitted data is a major concern. In remote login authentication schemes, there are two major requirements: i) proving the identity of a user and the server for legitimacy without exposing their private keys and ii) freedom for a user to choose and change his password (private key) efficiently. Most of the existing methods based on the bilinear property have some security breaches due to the lack of features and the design issues. In this paper, we develop a new scheme using the bilinear property of an elliptic point and the biometric characteristics. Our method provides many features along with three major goals. a) Checking the correctness of the password before sending the authentication message, which prevents the wastage of communication cost; b) Efficient password change phase in which the user is asked to give a new password after checking the correctness of the current password without involving the server; c) User anonymity - enforcing the suitability of our scheme for applications in which a user does not want to disclose his identity. We use BAN logic to ensure the mutual authentication and session key agreement properties. The paper provides informal security analysis to illustrate that our scheme resists all the security attacks. Furthermore, we use the AVISPA tool for formal security verification of our scheme.