• Journal of KIISE
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• v.43 no.8
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• pp.933-945
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• 2016

Sharing data by multiple users on the public storage, e.g., the cloud, is considered to be efficient because the cloud provides on-demand computing service at anytime and anywhere. Secure data sharing is achieved by fine-grained access control. Existing symmetric and public key encryption schemes are not suitable for secure data sharing because they support 1-to-1 relationship between a ciphertext and a secret key. Attribute based encryption supports fine-grained access control, however it incurs linearly increasing ciphertexts as the number of attributes increases. Additionally, the decryption process has high computational cost so that it is not applicable in case of resource-constrained environments. In this study, we propose an efficient attribute-based secure data sharing scheme with outsourceable decryption. The proposed scheme guarantees constant-size ciphertexts irrespective of the number of attributes. In case of static attributes, the computation cost to the user is reduced by delegating approximately 95.3% of decryption operations to the more powerful storage systems, whereas 72.3% of decryption operations are outsourced in terms of dynamic attributes.

• Journal of Families and Better Life
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• v.33 no.6
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• pp.65-75
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• 2015

This study aimed to analyze the preliminary data to increase the residents' satisfaction of mixed-generation house-sharing. For this purpose, we examined the recognition and demands of different generations and compared the differences. The participants were 50 elderly and 100 young people living in Seoul. The data were analyzed using SPSS statistics. The key findings are outlined below; 1. Most of the young people in our sample got to know about the house-sharing via various routes, but this option was not well known to the elderly. The interest in living in a house-sharing situation was higher among the young people than among the elderly. The reason why people were uninterested in house-sharing was their comfort in living alone. 2. Secure personal-space privacy and the choice of a housemate were regarded as the most important considerations in house-sharing by the young and the elderly, respectively. Young people anticipated a division of housework and the elderly were worried about communication with the younger generation. 3. Expected benefits tended to be higher in economic aspects for the young and in psychological aspects for the elderly. The elderly responded that they would be willing to share the kitchen and living room with the younger generation. Young people demanded necessary living facilities such as a laundry room and a community area with the elderly. The majority of the respondents from both generations said they would be able to solve problems through communication. In conclusion, public relations are needed to increase interest in house-sharing. The elderly and young should understand its purpose and treat each other as family members, not as house owners and tenants. There should be a manager who can coordinate the residents.

• Journal of Digital Convergence
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• v.18 no.7
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• pp.167-175
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• 2020

With the recent revitalization of the shared economy, bike-sharing services are gaining huge popularity in the bicycle sector. Bike-sharing services are characterized by reducing environmental pollution and borrowing bicycles at low prices. This study investigated the mechanisms for the formation of customer's continuance intention toward bike-sharing services. The theoretical framework clarified the role of perceived value and trust in enhancing customer's continuance intention. Perceived usefulness, perceived ease of use and perceived enjoyment are considered as the vital factors of enhancing perceived value and trust in a service provider. The research model was validated by data from 217 bike-sharing users in China. Both perceived value and trust in a service provider had a significant impact on user's continuance intention. However, the analysis results showed that perceived usefulness does not have a significant impact on both perceived value and trust in a service provider. Perceived ease of use and perceived enjoyment played a significant role in enhancing both perceived value and trust in a service provider. Our results are expected to provide academic and practical implications for bike-sharing services.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.19 no.1
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• pp.93-105
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• 2024

Car-sharing is a representative model of the sharing economy, and it is a service that rents or uses a car for the necessary time without owning a car. This industry is growing due to various factors such as technological advances, increasing awareness of environmental protection, and increasing demand for solving traffic congestion problems in cities. Accordingly, there is a need for a strategic approach for companies providing car-sharing services to respond quickly to market changes in order to expand market share and differentiate services. Accordingly, this study conducted a case study on open innovation activities between Gongcar and existing rental car companies, focusing on the research question "What effects do open innovation activities between car-sharing companies and existing rental car companies cause?" As a result of the study, it was confirmed that Gongcar have (1) the ability to actively respond to market fluctuations by establishing a flexible vehicle supply chain based on demand, (2) have significantly reduced growth capital expenditure (Growth Capex), and both cafe and rental car companies have (3) performed successful open innovation by improving key KPI indicators and recording financial performance. This study reveals how open innovation acts as a key business growth engine in the car-sharing industry, and its significance is found in that it empirically confirmed the successful implementation conditions of open innovation based on resource dependence theory.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.2
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• pp.147-155
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• 2013

Proxy re-encryption scheme has advantage where plaintext does not get exposed during re-encryption process. This scheme is popular for sharing server-saved data in case of cloud computing or mobile office that uses server to save data. Since previous proxy re-encryption schemes can use re-encryption key over and over again, it may abuse re-encryption. To solve this problem, conditional proxy re-encryption scheme was proposed. But, it is computationally expensive generate the same number of re-encryption key with the number of condition values. In this paper, we propose an efficient conditional proxy re-encryption scheme in terms of re-encryption key generation. The proposed scheme uses only encryption and decryption process. Therefore it has advantage to generate one re-encryption key for one person. The proposed scheme is secure against chosen-ciphertext attack.

• ETRI Journal
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• v.32 no.2
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• pp.292-301
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• 2010

Increasing convergence among heterogeneous radio networks is expected to be a key feature of future ubiquitous services. The convergence of radio networks in combination with dynamic spectrum allocation (DSA) could be a beneficial means to solve the growing demand for radio spectrum. DSA might enhance the spectrum utilization of involved radio networks to comply with user requirements for high-quality multimedia services. This paper proposes a simple spectrum allocation algorithm and presents an analytical model of dynamic spectrum resource allocation between two networks using a 4-D Markov chain. We argue that there may exist a break-even point for choosing whether or not to adopt DSA in a system. We point out certain circumstances where DSA is not a viable alternative. We also discuss the performance of DSA against the degree of resource sharing using the proposed analytical model and simulations. The presented analytical model is not restricted to DSA, and can be applied to a general resource sharing study.

• Korean Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.203-214
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• 1996

An information sharing system, namely World Design View, is developed for browsing product design data on the World Wide Web environment. For the last few years information sharing has been rapidly emerging as an important research issue in the areas of concurrent engineering, product data management, virtual manufacturing, and so on. Since we are mainly concerned with product development, the key information that needs be communicated and shared is product data. The developed system puts the major advantages of STEP, OODB, and VRML together. The STEP standard provides a consistent data exchange format and application interfaces among different CAD/CAM systems. OODB is efficient and effective in dealing with complex data structures often found in engineering applications. Virtual worlds for 3-D product models can be created by VRML which is networked via the global Internet and hyperlinked with WWW. The World Design View system can support for members of virtual design teams, possibly distributed all over the world, to share 3-D shape information quickly and easily.

• Journal of Sensor Science and Technology
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• v.14 no.1
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• pp.28-32
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• 2005

In this paper, a CMOS integrated detection circuit for capacitive type fingerprint sensor signal processing is described. We designed a detection circuit of charge-sharing sensing scheme. The proposed detection circuit increases the voltage difference between a ridge and valley. The test chip is composed of $160{\times}192$ array sensing cells (12 by $12.7{\;}mm^{2}$). The chip was fabricated on a 0.35 m standard CMOS process. Measured difference voltage between a ridge and valley was 0.95 V.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.7
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• pp.363-368
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• 1999

The parallel operation system of multiple uninterruptible power supplies(UPSs) is used to increase power capacity of the system or to secure higher reliability at critical loads. In the parallel operation of the two UPSs, the load-sharing control to maintain the current balance between them is a key technique. Because a UPS has low output impedance and quick response characteristics, in case of an unbalanced load inverter output current changes very rapidly and thereby can instantaneously reach an overload condition. In this study, high precise load-sharing controller is proposed and implemented for the parallel operation system of two UPSs with low impedance characteristics and this controller controls the frequency and the voltage to minimize the active power component and the reactive power component which are gotten from the current difference between two UPSs. And then a good performance of the proposed method is verified by experiments in the parallel operation system with two 40KVA UPSs.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.1-6
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• 2008

Organizations are increasingly adopting Knowledge Management Systems (KMS) to effectively manage knowledge within the organization and realize firm and operational level benefits. However, many KMS implementations fail to yield desired outcomes due to the lack of understanding of the antecedent of successful knowledge management. Prior studies have established that organizational cultural values are one of the key enablers of knowledge management. We develop a computational model of organizational knowledge processes and employ simulations to examine the impact of KMS in different organizational cultural settings. We find that cultural values that govern the employees' predisposition towards seeking knowledge from others have a greater influence on KMS effectiveness than those that govern the employees' attitudes towards sharing their knowledge with others. We also find that organizations with cultures that foster high levels knowledge sharing behaviors can expect performance gains if KMS implementations incorporate knowledge seeking activities into the employees' work processes.