• Journal of the Korea Society of Computer and Information
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• v.13 no.1
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• pp.161-167
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• 2008

As the authentication and the integrity methods based on the hash chain are popular, several certificate status validation methods based on the same function are proposd at the moment. In NOVOMODO, a CA generates and releases the hash value to each user. In Jianying Zhou's framework and Jong-Phil Yang's framework, a user generates and releases the hash value to verifier. Therefore, the CA loads are distributed to each user. However, these frameworks are based on the assumption that the CA's secret key is not lost or compromised and the certificates issued by the CA are error-free. Therefore, these frameworks are not suitable in real PKI environments. In this paper, as one hash value generated by CA is included in the user's certificate in addition, the certificate revocation published by CA using that value can be managed. The hash value included in user's certificate is the same for all users. The computation costs, the storage amounts and the release costs are small in the CA. And we modify the procedure for the signature and its validation in Jong-Phil Yang's framework. Our solution is more suitable than those frameworks in real PKI environments.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.17-22
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• 2008

The emergence of open source software (OSS) with its successful projects and its most prominent advantages creates a vast interest among academics and practitioners. However, it has been found that focusing on the developments of OSS to be successful is not adequate and the adoption of OSS by uses is also very important. Although there are a great number of useful and easy to use OSS has been developed, the adoption of OSS and usage in the market is very low. Based on the technology equity implementation model (EIM), this study examines user resistance in the adoption of OSS (i.e., switching from the current system to OSS). A survey has done regarding the adoption of Linux as the case of study. We have found that user resistance to change has negative effect on adoption intention, and switching benefits, switching costs and perceived value have significant relationships with user resistance to change.

• The Journal of Information Systems
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• v.21 no.2
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• pp.45-71
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• 2012

The purpose of the study is to propose the plans promoting IS acceptances under the circumstances where the IS usage is semi-mandatory. Since the IS usage is critical to secure the organization's competitiveness, many researchers have endeavored to investigate the factors in promoting IS acceptance. While TAM(Technology Acceptance Model) has been generally applied under the voluntary circumstance, under the mandatory circumstance did many researchers come to realized the limit of applying the TAM on IS acceptance. This resulted in various research trials to identify the IS acceptance under the mandatory circumstance. However, no research to promoting IS acceptance under the recommend circumstance where the corresponding users are recommend to the IS rather than alternative systems exits. The study applied the concept of switching costs to the research model, identified users' acceptance variations, and finally proposed the promotion plans for IS acceptance. The findings illustrate that IS dependence levels tend to be increased when both user satisfactions from a psychological perspective and monetary benefits from an economic perspective make the switching costs higher. The study stresses that organizations should provide information systems which reduce users' time, costs, and endeavors in performing their tasks, rather than require to use them by compulsion.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.720-723
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• 2004

This study is intended to propose a systematic approach for determining optimum Life-Cycle Cost (LCC)-effective seismic design for continuous PSC bridges considering lifetime expected seismic risks. In the paper, a set of cost function for LCC analysis of bridges is proposed. The total LCC functions consist of initial cost and direct/indirect damage costs considering repair/replacement costs, human losses and property damage costs, road user costs, and indirect socio-economic losses. The damage costs are expressed in terms of Park-Ang median global damage indices (Park and Ang, 1985) and lifetime damage probabilities. The proposed approach is applied to model bridges of both moderate seismicity regions like Korea and high seismicity regions like Japan. Since, in case of bridges, a number of parameters may have an influence on optimal target reliability, various sensitivity analyses are performed in this study. It may be expected that the proposed approach can be effectively utilized for the development of cost-effective performance criteria for design and upgrading of various types of bridges as well as continuous PC bridges.

• Proceedings of the Korea Water Resources Association Conference
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• 1992.07a
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• pp.479-489
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• 1992

A mathematical model for a long range water supply planning is develoted as a dynamic capacitated facility location problem, in which operation costs and two types of fixed costs are considered. The fixed costs are for water supply systems such as dams and reservoirs and for water conveyance systems of waterways or conduits from each water supply points. A Spreadsheet model is developed to support the efficiency of user interface and to implement a heuristic solution procedure. The proposed solution procedure utilizes SOLVER tool and it has been applied to a system with fictitious data but with reality and applicability in mind. As a result of the mathematical analysis, not only the most economic construction timings of surface water supply facilities and distribution systems but also the most economical water supply operating patterns are identified.

• Journal of Drive and Control
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• v.9 no.2
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• pp.46-53
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• 2012

This paper explains how eliminating contamination from the manufacturing processes will lead to better product quality and hence the need for reworking, a trouble free commissioning period and greatly improved production efficiency. All of these will reduce costs and energy usage. It will also ensure that the product is delivered to the customer in a condition that will ensure improved reliability and longer life, again reducing both energy and other operating costs. Correctly designing the contamination control measures will achieve and maintain the level of fluid cleanliness that is required by the end user. The filter is critical to cleanliness management and should be selected with the same degree of thought and consideration as for other major components. This paper explains the role that Cleanliness Management plays in the reducing the carbon footprint of systems and processes by making them perform more efficiently for longer periods. It also examines two differing ways of selecting filters to incorporate the features of newer designs, and shows how significant savings in the costs of ownership can be achieved using these approaches.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.67-84
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• 2000

In this paper, we address a network design problem including the decision of hub facility locatiions which is typically found in a communicatio and a transportation network design studies. Due to the administrative and the geographical restrictions, it is common to assume that each user should be assigned to only one hub facility. To construct such a network, three types of network costs should be considered: the fixed costs of establishing the hubs and the arcs in the network, and the variable costs associated with transversing the network. The complex problem is formulated as a mixed IP embedding a multicommodity flow problem. Exploiting its special structure, a dual-based heuristic is then developed, which yields near-optimal design plans. The test results indicate that the heuristic is an effective way to solve this computationally complex problem.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.5100-5119
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• 2018

Most of existing privacy-preserving multi-authorities attribute-based encryption schemes (PP-MA-ABE) only considers the privacy of the user identity (ID). However, in many occasions information leakage is caused by the disclosing of his/her some sensitive attributes. In this paper, we propose a collusion-resisting ciphertext-policy PP-MA-ABE (CRPP-MACP-ABE) scheme with hiding both user's ID and attributes in the cloud storage system. We present a method to depict anonymous users and introduce a managerial role denoted by IDM for the management of user's anonymous identity certificate ($AID_{Cred}$). The scheme uses $AID_{Cred}$ to realize privacy-preserving of the user, namely, by verifying which attribute authorities (AAs) obtain the blinded public attribute keys, pseudonyms involved in the $AID_{Cred}$ and then distributes corresponding private keys for the user. We use different pseudonyms of the user to resist the collusion attack launched by viciousAAs. In addition, we utilize IDM to cooperate with multiple authorities in producing consistent private key for the user to avoid the collusion attack launched by vicious users. The proposed CRPP-MACP-ABE scheme is proved secure. Some computation and communication costs in our scheme are finished in preparation phase (i.e. user registration). Compared with the existing schemes, our scheme is more efficient.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.68-77
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• 2018

Regarding demand response (DR) by residential users (R-users), the users try to reduce electricity costs by adjusting their power consumption in response to the time-varying price. However, their power consumption may be affected not only by the price, but also by user convenience for using appliances. This paper proposes a methodology for appliance scheduling (AS) that considers the user convenience based on historical data. The usage pattern for appliances is first modeled applying the copula function or clustering method to evaluate user convenience. As the modeling results, the comfort distribution or representative scenarios are obtained, and then used to formulate a discomfort index (DI) to assess the degree of the user convenience. An AS optimization problem is formulated in terms of cost and DI. In the case study, various AS tasks are performed depending on the weights for cost and DI. The results show that user convenience has significant impacts on AS. The proposed methodology can contribute to induce more DR participation from R-users by reflecting properly user convenience to AS problem.

• International Journal of Contents
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• v.5 no.2
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• pp.59-63
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• 2009

Since it is hard to use GPS for tracking mobile user in indoor environments, much research has focused on techniques using existing wireless local area network infrastructure. Signal strength received at a fixed location is not constant, so fingerprinting approach which use pattern matching is popular. But this approach has to pay additional costs to determine user location. This paper proposes a new approach to find user's location efficiently using an index scheme. After analyzing characteristics of RF signals, the paper suggests the data processing method how the signal strength values for each of the access points are recorded in a radio map. To reduce computational cost during the location determination phase, multidimensional indexes for radio map with the important information which is the order of the strongest access points are used.